GEMIGLIPTIN

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Jul 062015

GEMIGLIPTIN

1-[2(S)-Amino-4-[2,4-bis(trifluoromethyl)-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidin-7-yl]-4-oxobutyl]-5,5-difluoropiperidin-2-one

PHASE 3, DPP-IV inhibitor, Lg Life Sciences Ltd.

CAS 911637-19-9

Mol. Formula: C18H19F8N5O2

Mol. Weight:489.36

Gemigliptin (rINN), previously identified as LC15-0444, is an oral anti-hyperglycemic agent (anti-diabetic drug) of the new dipeptidyl peptidase-4 (DPP-4) inhibitor class of drugs.^[1] It is well known that glucose lowering effects of DPP-4 inhibitors are mainly mediated by GLP-1 and gastric inhibitory polypeptide (GIP) incretin hormones which are inactivated by DPP-4.

Gemigliptin was initially developed solely by LG Life Sciences. In 2010, Double-Crane Pharmaceutical Co. (DCPC) joined with LGLS to co-develop the final compound and collaborate on the marketing of the drug in China. LGLS also announced on Nov., 2010 that NOBEL Ilac has been granted rights to develop and commercialize gemigliptin in Turkey.

Gemigliptin, a dipeptidyl peptidase IV (CD26; DPP-IV; DP-IV) inhibitor, is currently undergoing phase III clinical trials at LG Life Sciences as an oral treatment for type II diabetes. The company is also testing the compound in phase II/III clinical studies for the treatment of patients with cisplatin-induced acute kidney injury.

DPP IV inhibitors have glucose-lowering effects mediated by GLP-1 incretin hormone which is inactivated by DPP IV. In 2010, gemigliptin was licensed to Beijing Double-Crane Pharmaceutical by LG Life Sciences for distribution and supply in China for the treatment of type 2 diabetes.

A New Drug Application (NDA) for gemigliptin in the treatment of type 2 diabetes was submitted to the Korea Food & Drug Administration (KFDA) in July 2011. Then on June 27, 2012, the KFDA has approved the manufacture and distribution of LG Life Sciences’ diabetes treatment, Zemiglo, the main substance of which is gemigliptin. Clinical trials for evaluating the safety and efficacy of gemigliptin in combination with metformin have been completed.

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Efficient synthesis of gemigliptin, a potent and selective DPP-4 inhibitor for the treatment of type 2 diabetes mellitus, has been developed. Gemigliptin were prepared from two key API starting materials, DP18 and DP57, in 75~80% yield and >99% purity over three steps under the GMP control: coupling, deprotection of N-Boc group, and final crystallization with L-tartaric acid. All steps were conducted in the same solvent system and the intermediates were isolated by simple filtration without distillation of solvent. The established process was validated obviously through the three consecutive batches for a commercial production.

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Clinical data
(3S)-3-amino-4-(5,5-difluoro-2-oxopiperidino)-1-[2,4-di(trifluoromethyl)-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidin-7-yl]butan-1-one
Routes of administration	Oral
Pharmacokinetic data
Bioavailability	94% (rat), 73% (dog), 26% (monkey)
Biological half-life	3.6 h (rat), 5.2 h (dog), 5.4 h (monkey)
Identifiers
CAS Registry Number	911637-19-9
ATC code	A10 BH06
PubChem	CID: 11953153
ChemSpider	10127461
UNII	5DHU18M5D6
Synonyms	LC15-0444
Chemical data
Formula	C₁₈H₁₉F₈N₅O₂
Molecular mass	489.36 g/mol

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History

The NDA for gemigliptin was submitted to KFDA in July, 2011 and it was approved on June 27, 2012. By the end of 2012, gemigliptin will be marketed in Korea as Zemiglo which is the fifth new DPP-4 inhibitor diabetes treatment in the world.

Mechanism of action

DPP-4 is a serine protease located on the cell surfaces throughout the body. In plasma, DPP-4 enzyme rapidly inactivates incretins including GLP-1 and GIP which are produced in the intestine depending on the blood glucose level and contribute to the physiological regulation of glucose homeostatis. Active GLP-1 and GIP increase the production and release of insulin by pancreatinc beta cells. GLP-1 also reduces the scretion of glucacon by pancreatic alpha cells, thereby resulting in a decreased hepatic glucose production. However these incretins are rapidly cleaved by DPP-4 and their effects last only for a few minutes. DPP-4 inhibitors block the cleavage of the gliptins and thus lead to an increasee insulin level and a reduced glucagon level in a glucose-dependent way. This results in a decrease of fasting and postprandial glycemia, as well as HbA1c levels.^[2]

Preclinical studies

Gemigliptin is a competitive, reversible DPP-4 inhibitor (IC50 = 16 nM) with excellent selectivity over other critical human proteases such as DPP-2, DPP-8, DPP-9, elastase,trypsin, urokinase and cathepsin G. Gemigliptin was rapidly absorbed after single oral dosing and the compound was eliminated with a half-life of 3.6 h, 5.2 h, and 5.4 h in the rat, dog, and monkey, respectively.

The bioavailability of gemigliptin in the rat, dog, and monkey was species-dependent with the values of 94%, 73%, and 26%, respectively. Following the oral administration of gemigliptin in the rat, dog and monkey, about 80% inhibition of plasma DPP-4 activity were observed at the plasma levels of 18 nM, 14 nM and 4 nM, respectively.

In the diet-induced obese (DIO) mice, gemigliptin reduced glucose excursion during OGTT in a dose dependent manner with the minimum effective dose of 0.3 mg/kg and enhanced glucose-stimulated plasma GLP-1 increase in a dose dependent manner reaching the maximum effect at the dose of 1 mg/kg.

Following 4 week oral repeat dosing in the DIO mice, gemigliptin reduced significantly HbA1c with the minimum effective dose of 3 mg/kg. In the beagle dog, gemigliptin significantly enhanced active GLP-1, decreased glucagon, and reduced glucose excursion during OGTT following a single dosing.

Studies on animals suggest its positive effect on hepatic and renal fibrosis .^[3]^[4] Data on human patients are still inconclusive .^[5]

Clinical studies

The dose-range finding phase 2 study was performed and 145 patients (91men and 54 women) with type 2 diabetes mellitus were enrolled. All three doses (50,100 and 200 mg groups) of gemigliptin significantly reduced the HbA_1c from baseline compared to the placebo group without a significant difference between the doses.

Subjects with a higher baseline HbA_1c (≥8.5%) had a greater reduction in HbA_1c. Insulin secretory function, as assessed using homeostasis model assessment-beta cell, C-peptide and the insulinogenic index, improved significantly with gemigliptin treatment. Insulin sensitivity, as assessed using homeostasis model assessment-insulin resistance, also improved significantly after 12 weeks of treatment.

The 50 and 200 mg groups had significantly reduced total cholesterol and low-density lipoprotein cholesterol levels at 12 weeks compared to the placebo group.

The incidences of adverse events were similar in all study subjects. Gemigliptin monotherapy (50 mg for 12 weeks) improved the HbA_1c, FPG level, oral glucose tolerance testresults, β-cell function and insulin sensitivity measures, and was well tolerated in subjects with type 2 diabetes.

Results of Phase 3 clinical trials which have been finished recently will be updated near future.

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WO 2006104356

http://www.google.co.in/patents/WO2006104356A1?cl=en

EXAMPLE 83: Synthesis of l-(f2SV2-amino-4-r2.4-bisftrifluoromethylV5.8-dihvdropyridor3.4-d]pyrimidin-7f6H^‘)

-yl1-4-oxobutyll-5.5-difluoropiperidin-2-one [1960]

[1961] 21 mg of the title compound was obtained in a yield of 56% at the same manner as in EXAMPLE 1, except that 42 mg (0.071 mmol) of t-butyl

{(lS)-3-[2,4-bis(trifluoromethyl)-5,8-dihydropyrido[3,4-d]pyrimidin-7(6H)-yl]-l-[(5,5

-difluoro-2-oxpiperidin-l-yl)methyl]-3-oxpropyl}carbamate obtained in

PREPARATION 143 was used. [1962] ¹K NMR (CD₃OD) δ 5.05-4.92 (2H, m), 3.98-3.91 (2H, m), 3.85-3.79 (2H, m),

3.70-3.59 (2H, m), 3.54-3.48 (IH, m), 3.36-3.33 (2H, m), 3.24 (IH, bra), 3.14 (IH, bra), 2.83-2.76 (IH, m), 2.72-2.53 (3H, m), 2.43-2.34 (2H, m) [1963] Mass (m/e) 490 (M+l)

[1964]

[1965] PREPARATION 144: Synthesis of t-butyl

(riSV3-r2.4-bisrtrifluoromethylV5.8-dihvdropyridor3.4-d]pyrimidin-7r6HVyl]-l-(rr2 S)-2-methyl-5-oxomorpholin-4-yl1methyl 1 -3-oxpropyl 1 carbamate

[1966] 14 mg of the title compound was obtained in a yield of 17% at the same manner as in PREPARATION 45, except that 43.7 mg (0.138 mmol) of (3S)-3-[(t-butoxycarbonyl)amino]-4-[2(S)-2-methyl-5-oxomoφholin-4-yl]-butanoic acid obtained in PREPARATION 55 and 42.5 mg (0.138 mmol) of 2,4-bis(trifluoromethyl)-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidine hydrochloric acid salt (product of PREPARATION 127) were used.

[1967] ¹K NMR (CDCl₃) δ 5.85-5.83 (IH, m), 5.09-4.92 (IH, m), 4.95-4.78 (IH, m),

4.23-4.08 (3H, m), 4.04-3.76 (3H, m), 3.73-3.66 (IH, m), 3.46-3.38 (IH, m), 3.36-3.21 (2H, m), 3.18-3.10 (2H, m), 2.96-2.81 (IH, m), 2.61-2.50 (IH, m), 1.43-1.41 (9H, m), 1.28-1.24 (3H, m)

[1968] Mass (m/e) 470 (M+l-Boc)

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WO 2012030106

https://www.google.com/patents/WO2012030106A2?cl=en

Reaction Scheme 1

PREPARATION 1: Synthesis of diethyl 2,2-difluoropentanedioate

To a solution of ethyl bromodifluoroacetate (33.2 g) in tetrahydrofuran (94.0 g) was added ethyl acrylate (8.2 g) and copper powder (10.9 g). After heating to 50℃, TMEDA (9.5 g) was added dropwise and the reaction mixture was then stirred for 3 hours at the same temperature. Upon disappearance of ethyl acrylate as the starting material, to the reaction solution was added methyl t-butyl ether (MTBE, 73.7 g) followed by addition of 10% aqueous ammonium chloride solution (49.8 g) dropwise, and the mixture was then stirred for 30 minutes. The remaining copper residue was removed by filtration through a celite, and methyl t-butyl ether (MTBE, 66.3 g) was added to separate the layers. The separated organic layer was washed successively with 10% aqueous NH₄Cl solution (66.3 g) and 3 N aqueous hydrochloric acid solution (99.6 g) in order and then distilled under reduced pressure to obtain 55.0 g of the desired title compound.

¹H NMR (400 MHz, CDCl₃) δ 1.26 (t, J=7.2 Hz, 3H), 1.37 (t, J=7.2 Hz, 3H), 2.37-2.49 (m, 2H), 2.55 (t, J=7.2 Hz, 2H), 4.16 (q, J=7.2 Hz, 2H), 4.29 (q, J=7.2 Hz, 2H).

PREPARATION 2: Synthesis of ethyl 4,4-difluoro-5-hydroxypentanoate

14.8 g of the compound obtained from the above Preparation 1 was diluted with ethanol (20.4 g) and tetrahydrofuran (69.1 g) and then cooled to 0℃. To this solution was slowly added sodium borohydride (NaBH₄, 3.5 g) stepwise while keeping the internal temperature below 30℃. After confirming completion of the reaction by ¹H NMR, the reaction solution was cooled to the temperature of 10℃ and 10% aqueous ammonium chloride solution (77.7 g) was slowly added. The remaining boron compound was filtered through celite, and the filtrate was distilled under reduced pressure to remove tetrahydrofuran. Then, ethyl acetate (105.2 g) was added to separate the layers, and the organic layer was distilled under reduced pressure to obtain 10.8 g of the title compound.

¹H NMR (400 MHz, CDCl₃) δ 1.23 (t, J=7.2 Hz, 3H), 2.15-2.29 (m, 2H), 2.49 (t, J=7.2 Hz, 2H), 3.69 (t, J=12.0 Hz, 2H), 4.12 (q, J=4.0 Hz, 2H).

EXAMPLE 1: Synthesis of ethyl 4,4-difluoro-5-{[(trifluoromethyl)sulfonyl]oxy}- pentanoate

To the solution of 10.8 g of the compound, as obtained from the above Preparation 2, dissolved in dichloromethane (100.2 g) was added pyridine (7.0 g), and then the mixture was cooled to -5.0℃. After completion of cooling, trifluoromethane sulfonic acid anhydride (20.1 g) was slowly added dropwise while keeping the reaction temperature below 6.3℃. After stirring the reaction solution for 30 minutes, 1.5 N hydrochloric acid solution was added dropwise at 0℃ to separate the layers. The aqueous layer as separated was back-extracted twice with dichloromethane (33.4 g), and the extracts were combined with the organic layer separated from the above and then distilled under reduced pressure to obtain 19.7 g of the title compound as a yellow oil.

¹H NMR (500 MHz, CDCl₃) δ 1.27 (t, J=7.2 Hz, 3H), 2.29-2.39 (m, 2H), 2.59 (t, J=7.6 Hz, 2H), 4.18 (q, J=7.2 Hz, 2H), 4.55 (t, J=11.6 Hz, 2H).

EXAMPLE 2-1: Synthesis of ethyl 4,4-difluoro-5-{[(nonafluorobutyl)sulfonyl]- oxy}pentanoate

To the solution of 100.0 g of the compound, as obtained from the above Preparation 2, dissolved in dichloromethane (300.0 ml) was added pyridine (65.7 g), and the mixture was then cooled to -10.0℃. After completion of cooling, nonafluorobutanesulfonic anhydride (477.4 g) was slowly added dropwise. After stirring the reaction solution for 3 hours, 1.0 N hydrochloric acid solution (300.0 ml) was added dropwise to separate the layers. The aqueous layer as separated was back extracted once with dichloromethane (500.0 ml), and the extracts were combined with the organic layer separated from the above and then distilled under reduced pressure to obtain 177.5 g of the title compound.

¹H NMR (500 MHz, CDCl₃) δ 1.26 (t, 3H, J=7.3 Hz), 2.30-2.36 (m, 2H), 2.58 (t, 2H, J=7.4 Hz), 4.16 (q, 2H, J=7.3 Hz), 4.57 (t, 2H, J=11 Hz).

EXAMPLE 2-2: Synthesis of ethyl 4,4-difluoro-5-{[(nonafluorobutyl)sulfonyl]- oxy}pentanoate

To the solution of 500.0 g of the compound, as obtained from the above Preparation 2, dissolved in dichloromethane (1000.0 ml) was added triethylamine (389.0 g), and the mixture was then cooled to 0℃. After completion of cooling, perfluorobutanesulfonyl chloride (948.80 g) was slowly added dropwise. The reaction solution was stirred for 3 hours at room temperature, distilled under reduced pressure, dissolved in methyl t-butyl ether (MTBE, 3000.0 ml) and then washed three times with water. The organic layer thus obtained was dehydrated with magnesium sulfate, filtered through a celite and then distilled under reduced pressure to obtain 960.0 g of the title compound.

EXAMPLE 3: Synthesis of methyl (2S)-2-[(tert-butoxycarbonyl)amino]-4-oxo- pentanoate

To 25.0 g of the starting material, (3S)-3-[(t-butoxycarbonyl)amino]-4-oxo- pentanoic acid, was added t-butanol (96.9 g) followed by the addition of Boc₂O (25.4 g) and dimethylaminopyridine (DMAP, 62.0 g, 0.5 mol%) at room temperature, and the reaction mixture was then stirred for 23 hours at 40℃. Upon completion of the reaction, ethylene dichloride (62.3 g) in t-butanol was added, and the mixture was then distilled under reduced pressure to obtain 30.7 g of the title compound.

¹H NMR (400 MHz, CDCl₃) δ 1.45 (s, 9H), 1.47 (s, 9H), 2.71 (dd, J=4.8, 16.4 Hz, 1H), 2.88 (dd, J=4.4, 16.4 Hz, 1H), 3.75 (s, 3H), 4.53 (m, 1H), 5.44 (br d, J=8.0 Hz, 1H).

EXAMPLE 4: Synthesis of tert-butyl (3S)-3-[(tert-butoxycarbonyl)amino]-4-hydroxy- butanoate

30.7 g of the compound obtained from the above Example 3 was dissolved in ethanol (112.3 g) and, after lowering the internal temperature to 10.5℃ sodium borohydride (NaBH₄, 5.7 g) was slowly added dropwise. This reaction solution was stirred while maintaining the temperature below 22℃. After confirming completion of the reaction by ¹H NMR and TLC, to the reaction solution was slowly added 3.0 N hydrochloric acid solution (30.7 g) dropwise at the internal temperature of 10℃ followed by addition of diluted 0.2% hydrochloric acid solution (100.0 g). The reaction solution was adjusted to pH 3~4 with addition of 9.0% aqueous hydrochloric acid solution, and then back-extracted twice with ethyl acetate (100.0 g) and toluene (44.0 g). The organic layer thus obtained was distilled under reduced pressure to obtain 25.1 g of the title compound.

¹H NMR (500 MHz, CDCl₃) δ 1.44 (s, 9H), 1.45 (s, 9H), 2.48-2.57 (m, 2H), 3.69 (d, J=4.9 Hz, 1H), 3.97 (m, 1H), 5.22 (bs, 1H).

EXAMPLE 5: tert-butyl (3S)-[(tert-butoxycarbonyl)amino]-4-[(methylsulfonyl)oxy]- butanoate

To 25.1 g of the compound obtained from the above Example 4 was added dichloromethane (133.0 g) and triethylamine (148.0 g), and the mixture was then cooled to 0℃. To this reaction solution was slowly added methanesulfonyl chloride (11.8 g) diluted with dichloromethane (39.9 g) dropwise for 50 minutes while maintaining the internal temperature below 12℃. After completion of the reaction, the reaction solution was washed with 0.5 N aqueous hydrochloric acid solution (120.0 g) and water (100.4 g), and then distilled under reduced pressure to obtain 31.5 g of the title compound.

¹H NMR (500 MHz, CDCl₃) δ 1.44 (s, 9H), 1.46 (s, 9H), 2.62 (d, J=6.0 Hz, 2H), 3.04 (s, 3H), 4.21 (m, 1H), 4.30 (d, J=5.2 Hz, 2H), 5.16 (br d, J=7.2 Hz, 1H).

EXAMPLE 6: Synthesis of tert-butyl (3S)-4-azido-3-[(tert-butoxycarbonyl)amino]- butanoate

Sodium azide (NaN₃, 11.6 g) was diluted with dimethylacetamide (DMAc, 260.0 g). After elevating the internal temperature to 80℃, a solution of 31.5 g of the compound, as obtained from the above Example 5, diluted with dimethylacetamide (DMAc, 45.0 g) was added thereto. The reaction proceeded at 80℃ for 2 hours. To the reaction solution were added toluene (251.0 g) and water (320.0 g) to separate the layers. The organic layer thus obtained was distilled under reduced pressure to obtain 24.0 g of the title compound.

¹H NMR (500 MHz, CDCl₃) δ 1.47 (s, 9H), 1.49 (s, 9H), 2.49 (d, J=6.0 Hz, 2H), 3.44-3.55 (m, 2H), 4.09 (br s, 1H), 5.14 (br s, 1H).

EXAMPLE 7: Synthesis of tert-butyl (3S)-4-amino-3-[(tert-butoxycarbonyl)amino]- butanoate

To 21.0 g of the compound obtained from the above Example 6 was added tetrahydrofuran (93.3 g) followed by the addition of triphenylphosphine (PPh₃, 21.0 g) at 40℃, the mixture was stirred for 2 hours at the same temperature, and water (3.8 g) was then added thereto. The reaction solution was distilled under reduced pressure, and the resulting triphenylphosphine oxide solid was diluted with toluene (26.0 g) and n-hexane (41.0 g), and then filtered off. The filtrate was adjusted to pH 2~3 with 1.0 N aqueous hydrochloric acid solution (110.0 g) and then subjected to separation of the layers. To remove any residual triphenylphosphine oxide solid, the aqueous layer obtained above was washed with dichloromethane (100.0 g) and then adjusted to pH 8~9 with 28% aqueous ammonia solution (7.6 g). The aqueous solution thus obtained was extracted with dichloromethane (100.0 g) and distilled under reduced pressure to obtain 8.5 g of the title compound as a white solid.

¹H NMR (500 MHz, CDCl₃) δ 1.44 (s, 9H), 1.45 (s, 9H), 2.45 (d, J=6.1 Hz, 2H), 2.77 (d, J=5.5 Hz, 2H), 3.87 (br s, 1H), 5.22 (br s, 1H).

EXAMPLE 8: Synthesis of N,N-dibenzyl-L-N(Boc)-aspartamide 4-tert-butyl ester

N-Boc-L-aspartic acid 4-t-butyl ester (29.0 g, 0.10 mol) was added to THF (200 ml). After cooling to temperature below -5℃, to the reaction solution was added isobutylchloroformate (13.0 ml, 0.10 mol) followed by addition of N-methyl morpholine (12.0 ml, 0.10 mol) dropwise, and the reaction mixture was stirred for over 30 minutes. To the reaction mixture was added dropwise dibenzylamine (21.1 ml, 0.11 mol), and the mixture was then stirred for over 3 hours and monitored for the reaction progress by TLC (EtOAc: Hexane=1:4). Upon completion of the reaction, the reaction solution was stirred with addition of ethyl acetate (300.0 mL) and 1 N hydrochloric acid to separate the layers, and distilled under reduced pressure to precipitate a solid. The solid was filtered and washed with ethyl acetate (100 ml), and then the washings were concentrated by distillation again under reduced pressure. The residue was then subjected to silica gel column to obtain the purified desired product (41.7 g, 0.89 mol).

¹H NMR (400 MHz, CDCl₃) δ: 7.32 (m, 5H), 7.20 (m, 5H), 5.39 (d, J=7.2 Hz, 1H), 5.30 (m, 1H), 4.87-4.77 (m, 2H), 4.48-4.39 (m, 2H), 2.72 (dd, J=15.8 Hz, J=8.0 Hz, 1H), 2.56 (dd, J=15.8 Hz, J=6.4 Hz, 1H), 1.43 (s, 9H), 1.37 (s, 9H).

Mass (ESI, m/z): 491 (M+Na), 469 (M+H), 413 (M-55).

EXAMPLE 9: Synthesis of N, N-diallyl-L-N(Boc)-aspartamide 4-tert-butyl ester

L-N(Boc)-aspartic acid 4-t-butyl ester (5.00 g, 17.3 mol) was added to THF (50 ml). After cooling to temperature below -5℃, to the reaction solution was added isobutylchloroformate (2.26 ml, 17.3 mol) followed by addition of N-methyl morpholine (1.90 ml, 17.3 mol) dropwise, and the reaction mixture was stirred for over 30 minutes. To the reaction mixture was added dropwise diallylamine (2.35 ml, 19.0 mol), and the mixture was then stirred for over 3 hours and monitored for the reaction progress by TLC (EtOAc: Hexane=1:4). Upon completion of the reaction, the reaction solution was stirred with addition of ethyl acetate (60 ml) and 1 N hydrochloric acid and, after separating the layers, concentrated by distillation under reduced pressure. The residue was then subjected to silica gel column to obtain the purified desired product (6.0 g, 16.3 mol).

¹H NMR (400 MHz, CDCl₃) δ: 5.78 (m, 2H), 5.30 (m, 1H), 5.23-5.11 (m, 1H), 5.30 (m, 1H), 4.93 (m, 1H), 4.11-3.84 (m, 4H), 2.68 (dd, J=15.8 Hz, J=8.0 Hz, 1H), 2.51 (dd, J=15.8 Hz, J=8.0 Hz, 1H), 1.44 (s, 9H), 1.42 (s, 9H).

Mass (ESI, m/z): 391 (M+Na), 369 (M+H), 313 (M-55).

EXAMPLE 10: Synthesis of N,N-dibenzyl-4-amino-3(S)-N(Boc)-aminobutanoic acid 4-tert-butyl ester

10.0 g of the compound obtained from the above Example 8, Ru₃(CO)₁₂ (136 mg, 1mol%), and diphenylsilane (19.7 ml, 106.7 mmol) were added to tetrahydrofuran (50 ml), and the reaction solution was stirred under reflux for over 40 hours. The reaction solution was extracted with ethyl acetate (200 ml) and concentrated by distillation under reduced pressure. The residue was then subjected to silica gel column to obtain the purified desired product (4.7 g, 10.5 mmol).

¹H NMR (400 MHz, CDCl₃) δ: 7.31-7.20 (m, 10H), 5.12 (bs, 1H), 3.90 (bs, 1H), 3.63 (d, J=12.0 Hz, 2H), 3.48 (d, J=12.0 Hz, 2H), 3.24 (m, 1H), 3.16 (bs, 1H), 2.42 (m, 2H), 1.81 (m, 1H), 1.59 (m, 9H), 1.46 (s, 9H), 1.06 (s, 9H).

Mass (ESI, m/z): 455 (M+H), 441 (M-13).

EXAMPLE 11: Synthesis of tert-butyl (3S)-4-amino-3-[(tert-butoxycarbonyl)amino]- 4-oxobutanoate

360.0 g of the starting material, N-Boc-Asp(O-t-Bu)OH, together with Boc₂O (353.0 g) and ammonium bicarbonate (NH₄HCO₃, 123.9 g) was added to dimethylformamide (1174.6 g), and pyridine (61.0 g) was added dropwise thereto at room temperature, and the reaction mixture was then stirred for about 3 hours. Upon completion of the reaction, water (1440 ml) and toluene (1800 ml) were added to the reaction solution and stirred for 30 minutes to separate the layers. The organic layer thus obtained was distilled under reduced pressure to remove t-butanol and toluene to obtain the title compound, which was directly used in the next reaction.

EXAMPLE 12: Synthesis of (S)-tert-butyl 3-(tert-butoxycarbonylamino)-3-cyanopropanoate

To the compound obtained from Example 11 was added dimethylformamide (1019.5 g) followed by addition of cyanuric chloride (112.0 g) dropwise for 1.5 hours at temperature below 25℃. The reaction solution was stirred for one hour at room temperature, and then 0.1 N aqueous sodium hydroxide solution (1850.0 g) and toluene (1860 ml) were added thereto to separate the layers. The organic layer thus obtained was washed once again with water (700 ml) and then distilled under reduced pressure to obtain 318.3 g of the title compound.

¹H NMR (500 MHz, CDCl₃) δ: 1.44 (s, 9H), 1.45 (s, 9H), 2.45 (d, J=6.1 Hz, 2H), 2.77 (d, J=5.5 Hz, 2H), 3.87 (br s, 1H), 5.22 (br s, 1H).

EXAMPLE 13: Synthesis of tert-butyl (3S)-4-amino-3-[(tert-butoxycarbonyl)amino]- butanoate

To 212.1 g of the compound obtained from the above Example 12 was added acetic acid (4000 ml) followed by addition of 20 wt% Pd(OH)₂ (1.1 g) at 40℃. The mixture was stirred for 8 hours while keeping the internal temperature below 45℃ and 3 atmospheric pressure of hydrogen. Upon completion of the reaction, the reaction solution was distilled under reduced pressure to remove acetic acid, diluted with toluene (640 L) and then filtered through a celite. To the filtrate was added 0.25 N aqueous hydrochloric acid solution (1060 ml) to separate the layers. The aqueous layer thus obtained was basified with aqueous ammonia solution (543.1 g) and then extracted with methyl t-butyl ether (MTBE, 1000 ml). The organic layer thus obtained was distilled under reduced pressure to obtain 185.0 g of the title compound.

EXAMPLE 14: Synthesis of 3-t-butoxycarbonylamino-4-(5,5-difluoro-2-oxo- piperidin-1-yl)-butyric acid t-butyl ester

Triethylamine (13.2 g) was added to 16.0 g of the compound obtained from the above Example 1 or 2-1 or 2-2, and 14.1 g of the compound obtained from the above Example 7 or 13, and the mixture was then stirred for 21 hours at 40℃. Then, dichloromethane (154.8 g) and acetic acid (18.3 g) were added, and the mixture was stirred for 5 hours at room temperature. To the resulting reaction solution was added 0.5 N aqueous hydrochloric acid solution (116.8 g) and then, the mixture was stirred for 30 minutes to separate the layers. The organic layer thus obtained was distilled under reduced pressure to obtain 23.6 g of the title compound.

¹H NMR (500 MHz, CDCl₃) δ: 1.42 (s, 9H), 1.46 (s, 9H), 2.27 (m, 2H), 2.40-2.64 (m, 4H), 3.20 (dd, J=4.3, 13.5 Hz, 1H), 3.56-3.70 (m, 2H), 3.76-3.91 (m, 2H), 4.16 (m, 1H), 5.20 (d, J=8.6 Hz, 1H).

EXAMPLE 15: Synthesis of 3-t-butoxycarbonylamino-4-(5,5-difluoro-2-oxo- piperidin-1-yl)-butyric acid

23.6 g of the compound obtained from the above Example 14 was added to dichloromethane (20.0 g) followed by addition of H₃PO₄ (30.0 g), and the mixture was stirred for 16 hours at room temperature. After confirming the detachment of all of t-butyl group and t-butyloxycarbonyl group, the reaction solution was adjusted to pH 7.0~8.0 with 10 N aqueous hydrogen peroxide, and Boc₂O (16.0 g) was added thereto. After completion of the addition, 10 N aqueous hydrogen peroxide was used to maintain the pH of the reaction solution at 8.0~9.0. After stirring for 3 hours, the resulting sodium phosphate was filtered off, and the filtrate was then adjusted to pH 2.0~3.0 with 3.0 N aqueous hydrochloric acid solution. The resulting solid was filtered and dried under nitrogen to obtain 14.5 g of the title compound.

¹H NMR (500 MHz, CDCl₃) δ: 1.32 (s, 9H), 2.20-2.43 (m, 6H), 3.26-3.31 (m, 2H), 3.61 (m, 1H), 3.81 (m, 1H), 4.02 (m, 1H), 6.73 (d, J=8.6 Hz, 1H), 12.16 (s, 1H).

For the title compound resulting from the above, its enantiomeric isomers―i.e. S-form and R-form―were measured by HPLC (high-performance liquid chromatography), and an excess of the enantiomeric isomers (S vs. R form) (enantiomeric excess; ee) was then calculated as being ee > 99%. On the other hand, in case of the Comparative Example prepared according to the prior method based on WO 06/104356, as described below, the excess (ee) of enantiomeric isomers (S vs. R form) was 80%. From this, it can be identified that the compound of formula (2) having an optically high purity could be obtained according to the method of the present invention.

COMPARATIVE EXAMPLE 1: Synthesis of 3-t-butoxycarbonylamino-4-(5,5- difluoro-2-oxo-piperidin-1-yl)-butyric acid t-butyl ester

COMPARATIVE EXAMPLE 1-1: Synthesis of methyl 5-amino-4,4-difluoro- pentanoate HCl

To 10.0 g of the compound obtained from Example 1 was added 40 ml of anhydrous ammonia solution (7 M solution in methanol), and the mixture was stirred for 3 hours. The reaction solution was distilled and 30 ml of hydrochloric acid solution saturated with methanol was added dropwise thereto. The reaction mixture was stirred at room temperature and then distilled to obtain 7.2 g of the title compound as a white solid.

¹H NMR (500 MHz, CD₃OD) δ: 2.35 (m, 2H), 2.59 (t, J=7.6 Hz, 2H), 3.49 (t, J=15.3 Hz, 2H), 3.68 (s, 3H).

COMPARATIVE EXAMPLE 1-2: Synthesis of 3-t-butoxycarbonylamino-4-(5,5- difluoro-2-oxo-piperidin-1-yl)-butyric acid t-butyl ester

To the solution of the compound (1.93 g), as obtained from the above Example 4, dissolved in dichloromethane (20.0 g) and H₂O (4.0 g) were added NaBr (0.8 g) and TEMPO (11 mg, 1 mol%). To this reaction solution was slowly added a solution of 5% NaOCl (11.5 g) and NaHCO₃ (1.7 g) dissolved in H₂O (12.0 g) dropwise for about 2 hours while maintaining the temperature below 5℃. Upon completion of dropwise addition, the reaction solution was stirred for 30 minutes to separate the layers. To the organic layer thus obtained was added the compound (1.6 g) obtained from the above Comparative Example 1-1. After stirring for 15 minutes at room temperature, NaBH(OAc)₃ (2.23 g) was added to the reaction solution. After stirring for about 19 hours, 10% aqueous NaHCO₃ solution (20.0 g) and 0.5 N aqueous hydrochloric acid solution (20.0 g) were added dropwise to the reaction solution to separate the layers. The organic layer thus obtained was dehydrated under anhydrous MgSO₄ to obtain 2.0 g (yield 73%) of the same title compound as Example 14, as a yellow solid. For the title compound resulting from the above, its enantiomeric isomers―i.e., S-form and R-form―were measured by HPLC (high-performance liquid chromatography), and an excess (ee) of the enantiomeric isomers (S vs. R form) was then calculated as being ee = 80%.

WO2006104356A1	Mar 30, 2006	Oct 5, 2006	Seong Cheol Bu	Dipeptidyl peptidase-iv inhibiting compounds, methods of preparing the same, and pharmaceutical compositions containing the same as an active agent
EP0279435A2 *	Feb 18, 1988	Aug 24, 1988	BASF Aktiengesellschaft	Process for the reduction of mono- and dicarboxylic acids
US5556982 *	Jul 12, 1993	Sep 17, 1996	Neorx Corporation	Metal radionuclide labeled proteins for diagnosis and therapy
US20080039517 *	Aug 7, 2007	Feb 14, 2008	Washburn David G	Pyrrolidinone anilines as progesterone receptor modulators

Footnotes

Lim KS, Kim JR, Choi YJ, Shin KH, Kim KP, Hong JH, Cho JY, Shin HS, Yu KS, Shin SG, Kwon OH, Hwang DM, Kim JA, Jang IJ (October 2008). “Pharmacokinetics, pharmacodynamics, and tolerability of the dipeptidyl peptidase IV inhibitor LC15-0444 in healthy Korean men: a dose-block-randomized, double-blind, placebo-controlled, ascending single-dose, Phase I study”. Clin Ther 30 (10): 1817–30. doi:10.1016/j.clinthera.2008.10.013. PMID 19014837.
Ábel T. “A New Therapy of Type 2 Diabetes: DPP-4 Inhibitors”. In Rigobelo EC. Hypoglycemia – Causes and Occurrences. Croatia: InTech. pp. 3–52. doi:10.5772/23604. ISBN 978-953-307-657-7.
Kaji K (Mar 2014). “Dipeptidyl peptidase-4 inhibitor attenuates hepatic fibrosis via suppression of activated hepatic stellate cell in rats.”. J Gastroenterol.. 49 (3): 481–91.doi:10.1007/s00535-013-0783-4. PMID 23475323.
Min HS (Jun 2014). “Dipeptidyl peptidase IV inhibitor protects against renal interstitial fibrosis in a mouse model of ureteral obstruction.”. Lab Invest. 94 (5): 598–607.doi:10.1038/labinvest.2014.50. PMID 24687121.
Gouni-Berthold I (2014). “The role of oral antidiabetic agents and incretin mimetics in type 2 diabetic patients with non-alcoholic Fatty liver disease.”. Curr Pharm Des. 20 (5): 3705–15.PMID 24040873.

External links

Official site

DAVID G. WASHBURN ET AL.: ‘Discovery or orally active, pyrrolidinone-based progesterone receptor partial agonist‘ BIOORGANIC & MEDICINAL CHEMISTRY LETTERS vol. 19, no. 16, 2009, pages 4664 – 4667, XP026419052
2	*	MONICA LOPEZ-GARCIA ET AL.: ‘Synthesis of (R)-3,4- diaminobutanoic acid by desymmetrization of dimethyl 3-(benzylamino)-glutarate through enzymatic ammonolysis‘ JOURNAL OF ORGANIC CHEMISTRY vol. 68, no. 2, 2003, pages 648 – 651, XP055105976

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UGI PRODUCT

PROCESS, spectroscopy, SYNTHESIS, Uncategorized Comments Off

Jul 052015

To synthesize a Ugi adduct from phenanthrene-9-carboxaldehyde, 1-heptylamine, tert-butylisocyanide and crotonic acid in methanol using Ugi 4CR

Procedure

To a one gram vial, charged with methanol (1mL) heptylamine, phenanthrene-9-carboxaldehyde, crotonic acid and tert-butyl isonitrile (0.5mmol each) was added in that order. After each addition, the resulting solution was vortexed for 15 seconds (or more) and confirmed that a homogeneous solution had been obtained. The vial was capped tight and left at room temperature for 3 days. The solution formed solid upon moving it to another spot. The obtained solid was washed with methanol (3 x 500uL), centrifuged each time to obtain a white residue. The wet product was set under a high vac to remove the solvent.

Characterization : White powder; M.pt~ 179-181C; H-NMR ( external image delta.gif

ppm, CDCl3) 0.30 (m, 1H), 0.54-0.95 (m, 10H), 1.05-1.2 (m, 1H ), 1.39 (s, 9H), 1.89 (d, 3H J 6.8Hz), 2.86 (bs, 1H), 3.28-3.60 (m 2H ), 5.79 (s,1H), 6.24 (d,1H J 15Hz), 6.87 (s 1H), 7.0-7.15 (m 1H), 7.56-7.76 (m 4H), 7.88 (d 1H J 7.85 Hz), 7.92-8.04 (m 2H), 8.68 (d 1H J 8.25 Hz), 8.73 (d 1H J 8.25Hz); 13C NMR ( external image delta.gif

ppm, CDCl3) 13.8, 18.2, 22.1, 26.2, 27.9, 28.6, 29.9, 31.0, 45.5, 51.7, 57.8, 122.0, 122.4, 123.1, 124.1, 126.8, 126.9, 127.43, 127.48, 128.9, 129.15, 129.16, 130.3, 130.47, 130.9, 131.0, 142.7, 166.9, 169.9; IR (KBr, 1/cm): v=3315, 3080, 2926, 2855, 1663, 1614, 1452, 1419, 748, 728; HRMS m/z calcd for C31 H40 N2 O2 : 495.298748 [M+Na]; found 495.2997.

Characterization amount: 118.5 mg

m.p. 179-181C
HNMR(50mg in 700uL CDCl3)
CNMR(50mg in 700uL CDCl3)
HRMS (FAB) [M+Na]
Nominal Mass (FAB) [M+H]
Nominal Mass (FAB) [M+Na]
IR (KBr)

Conclusion

A Ugi product was successfully synthesized in 50% yield.

Sitagliptin

diabetes, Uncategorized Comments Off

Jul 052015

Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry

A practical and economical approach to synthesize sitagliptin

Volume 43, Issue 24, 2013

DOI:: 10.1080/00397911.2013.773353

Kuaile Lin^a, Zhengyan Cai^a & Weicheng Zhou^a^*

pages 3281-3286

1Kuaile Lin, Zhengyan Cai, Weicheng Zhou*

State Key Lab of New Drug & Pharmaceutical Process, Shanghai Key Lab of

Anti-Infectives,
Shanghai Institute of Pharmaceutical Industry, State Institute
ofPharmaceutical Industry, Shanghai 200437, China

* Corresponding author: Weicheng Zhou, profzhouwc@yahoo.com.cn, Tel./fax: +8621 35052484

http://www.tandfonline.com/doi/abs/10.1080/00397911.2013.773353?journalCode=lsyc20#.VPRLp_mUc9s

Economic syntheses of sitagliptin phosphate monohydrate, acknowledged as the first dipeptidyl peptidase 4 (DPP-4) inhibitor, have been achieved in an overall yield of 42.4% in four steps from 1-{3-(trifluoromethyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl}-4-(2,4,5-trifluorophenyl)butane-1,3-dione. The key stereoselective reduction of this process was carried out by NaBH₄/HCOOH instead of expensive and toxic catalysts or ligands.
LOOK FOR SUPPLEMENTARY INFO IN ABOVE PAPER

tga

………………………….

NMR
SEE AN ONLINE NMR BELOW

NMR…………http://file.selleckchem.com/downloads/nmr/S400205-Sitagliptin-phosphate-monohydrate-HNMR-Selleck.pdf

………………….

PAPER

Graphical abstract: Quantitative analysis of sitagliptin using the 19F-NMR method: a universal technique for fluorinated compound detection

http://pubs.rsc.org/en/content/articlelanding/2014/an/c4an01681e#!divAbstract

Quantitative analysis of sitagliptin using the ¹⁹F-NMR method: a universal technique for fluorinated compound detection

Fen-Fen Zhang,^a
Meng-Hong Jiang,^b
Lin-Lin Sun,^a
Feng Zheng,^a
Lei Dong,^a
Vishva Shah,^c
Wen-Bin Shen*^d and

Ya Ding*^a

Hide Affiliations

Corresponding authors

State Key Laboratory of
Natural Medicines, Department of Pharmaceutical Analysis, China
Pharmaceutical University, Nanjing 210009, China E-mail:
ayanju@163.com

Shanghai Institute for Food and Drug Control, Shanghai 201203, China

Department of Chemistry
and Chemical Engineering, Royal Military College of Canada, Kingston,
Canada

Pharmaceutical Research
Institute, China Pharmaceutical University, Nanjing 210009, China E-mail:
cpunmrswb@163.com

Analyst, 2015,140, 280-286

DOI:
10.1039/C4AN01681E

Vishva Shah, Royal Military College of Canada

CHECK OUT PREDICTIONS
UNDERSTAND THE SIGNALS
PREDICTIONS 1H NMR

Sitagliptin phosphate monohydrate NMR spectra analysis, Chemical CAS NO. 654671-77-9 NMR spectral analysis, Sitagliptin phosphate monohydrate H-NMR spectrum

PREDICTIONS 13 C NMR
LOOK FOR DELTA VALUES OF GROUPS
Sitagliptin phosphate monohydrate NMR spectra analysis, Chemical CAS NO. 654671-77-9 NMR spectral analysis, Sitagliptin phosphate monohydrate C-NMR spectrum
COSY NMR PREDICTION

BELOW PAPENT DESCIBES THIS DRUG WELL IS RANDOMLY CHOSEN

http://www.google.com/patents/EP2491040A2?cl=en

The present invention relates to a novel method of preparing sitagliptin, and intermediates used therein. BACKGROUND OF THE INVENTION

Sitagliptin phosphate is a selective inhibitor of the second generation dipeptidyl peptidase IV (DPP-4) and used to maintain the systemic concentration of incretin hormone at an optimum level. Sitagliptin phosphate monohydrate was approved in October 2006 by the US Food and Drug Administration (FDA) as an adjuvant in dietetics or kinesiatrics for treatment of patients with type-2 diabetes and it is marketed in the United States and Korea under the trade name of JANUVIA™ (as a single agent).

Various methods for preparing sitagliptin and sitagliptin phosphate have been developed. For example, International Patent Publication WO 2003/004498 discloses a method of introducing a chiral-amine group using a chiral pyrazine derivative and to prepare sitagliptin by Arndt-Eistert Homologation using t-butoxylcarbonylamino-4-(2,4,5-trifluorophenyl)-butyric acid as a sitagliptin intermediate, as shown in Reaction Scheme 1.

Reaction Scheme 1

Wherein,

Boc is tert-butoxycarbonyl, TEA is trimethylamine, HOBt is 1- hydroxybenzotriazole, EDC is N-ethyl-N’-(3- dimethylaminopropyl)carbodiimide, and DIPEA is N,N-diisopropylethylamine.

International Patent Publication WO 2004/087650 discloses a method for preparing sitagliptin phosphate comprising the steps of: subjecting (2,4,5- trifluorophenyl)acetic acid to two-step reactions to obtain methyl 4-(2,4,5- trifluorophenyl)-3-oxophenylbutylate; conducting a stereoselective reduction of the resulting compound in the presence of (S)-BrNAP-RuCl₂-Et₃N under a high hydrogen pressure; hydrolyzing the reduced product to obtain (3S)-3-hydroxy- 4-(2,4,5-trifluorophenyl)-butyric acid, a key sitagliptin intermediate; and subjecting (3S)-3-hydroxy-4-(2,4,5-trifluorophenyl)-butyric acid to seven-step processes to obtain sitagliptin phosphate, as shown in Reaction Scheme 2.

Reaction Scheme 2

Wherein,

BINAP is 2,2′-bis(diphenylphosphino)-l,l’-binaphthyl, EDC is N-ethyl-N’-(3- dimethylaminopropyl)carbodiimide, Bn is benzyl, DIAD is diisopropyl azodicarboxylate, NMM is N-methylmorpholine, and ACN is acetonitrile.

Further, International Patent Publication WO 2004/085661 discloses a method for preparing sitagliptin by stereoselectively reducing an enamine using a platinum catalyst, PtO₂, as shown in Reaction Scheme 3. Reaction Scheme 3

Further, WO 2005/097733 discloses a method for preparing sitagliptin by stereoselectively reducing an enamine employing a rhodium-based catalyst, [Rh(cod)Cl]₂ having a chiral diphosphine ligand, as shown in Reaction Scheme 4.

The document [J. Am. Chem. Soc, 2009, 131, p.l 1316-11317] discloses a method for preparing sitagliptin by stereoselectively reducing an enamine using a ruthenium-based catalyst, Ru(OAc)₂ having a chiral diphosphine ligand, and International Patent Publication WO 2009/064476 discloses a method for preparing sitagliptin by stereoselectively reducing an enamine using Ru(OAc)₂and a chiral diphosphine ligand, or using a chiral acid together with a borohydride reducing agent (e.g., NaBH₄).

Reaction Scheme 5

Example 1: Preparation of (2S)-2-(2,4,5-trifluorobenzyl)- oxirane

Step 1 : Preparation of (2S)-3-(2A5-trifluorophenyl)-l-chloro-2-propanol

Magnesium (Mg) (1.26 g) was suspended in tetrahydrofuran (THF) (10 ml), and a drop of 1,2-dibromoethane was added thereto. To the resulting mixture, 2,4,5-trifluorobenzene bromide (0.55 g) was added dropwise slowly and then stirred for 30 min. 2,4,5-trifluorobenzene bromide (9.0 g) dissolved in THF (50 ml) was added slowly dropwise to the resulting mixture for 30 min and then stirred at room temperature for 1 hour. Cul (0.72 g) was added to the resulting mixture and the reaction temperature was cooled to 0°C . (S)- epichlorohydrin (4.1 ml) dissolved in THF (40 ml) was added dropwise to the resulting mixture slowly over 30 min, heated to room temperature, and stirred for 2 hours. Satuated NH4CI (50 ml) and ethyl acetate (50 ml) were added to the resulting mixture, and the organic layer formed thereafter was separated. The separated organic layer was washed with 50 ml of satuated saline, dried over MgSO₄, and filtered. The organic solvent was removed from the filtrate under a reduced pressure to obtain the title compound.

Step 2: Preparation of (2S)-2-(2,4,5-trifluorobenzyl)-oxirane

(2S)-3-(2,4,5-trifluorophenyl)-l-chloro-2-propanol obtained in step 1 was dissolved in methanol (50 ml), and NaOH (2.3 g) was added dropwise thereto. The resulting mixture was stirred for 1 hour and methanol was removed therefrom under a reduced pressure. Water (50 ml) and ethyl acetate (50 ml) were added to the resulting mixture, and the organic layer formed thereafter was separated. The separated organic layer was washed with satuated saline, dried over MgSO₄, and filtered to remove MgSO₄. The organic solvent was removed from the filtrate under a reduced pressure to obtain the title compound (6.8 g; yield: 80%).

1H-NMR(300MHz, CDC1₃): 6 7.17-7.05 (2H, m), 6.96-6.88 (2H, m), 3.16-3.13 (1H, m) 3.14 (1H, dd, J=4.68, 14.7), 2.82-2.77 (2H, m), 2.54-2.47 (1H, m). Preparation Example 2: Preparation of (2S)-2-(2,4,5-trifIuorobenzyl)- oxirane

Step 1 : Preparation of (2S)-3-(2A5-trifluorophenyl)-l-chloro-2-propanol

2N -PrMgCl (26 ml) suspended in THF was added dripwise to the 2,4,5-trifluorobenzene bromide (9.55 g) dissolved in THF (30 ml) at -15 ^°C for 60 min. Cul (0.72 g) was added thereto at -15 ^°C , and heated to -10 ^°C . (S)- epichlorohydrin (4.1 ml) dissolved in THF (40 ml) was added slowly to the resulting mixture, and stirred at 0 ^°C for 1 hour. Satuated NH₄C1 (50 ml) and ethyl acetate (50 ml) were added to the resulting mixture, and the organic layer formed thereafter was separated. The separated organic layer was washed with 50 ml of satuated saline, dried over MgSO₄, and filtered to remove MgSO₄. The organic solvent was removed from the filtrate under a reduced pressure to obtain the title compound.

Step 2: Preparation of (2S)-2-(2,4,5-trifluorobenzyl)-oxirane (2S)-3-(2,4,5-trifluorophenyl)-l-chloro-2-propanol obtained in step 1 was dissolved in 50 ml of methanol, and NaOH (2.3 g) was added dropwise thereto. A mixture was stirred for 1 hour, and methanol was removed therefrom under a reduced pressure. Water (50 ml) and ethyl acetate (50 ml) were added thereto, and the organic layer formed thereafter was separated. The separated organic layer was washed with satuated saline, dried over MgSO₄, and filtered to remove MgSO₄. The organic solvent was removed from the filtrate under a reduced pressure to obtain the title compound (7.6 g; yield: 85%). Example 1: Preparation of Sitagliptin

Step 1: Preparation of (2R)-l-(2,4,5-trifluorophenyl -4-pentene-2-ol

CuBr(CH₃)₂ (3.3 g) was added to a reactor under the nitrogen atmosphere and cooled to -78 ^°C . Vinylmagnesium bromide (240 ml) was added slowly to the reactor and stirred for 20 min. (2S)-2-(2,4,5- trifluorobenzyl)-oxirane (30 g) dissolved in THF (90 ml) was added dropwise slowly over 30 min, stirred at -78 °C for 30 min, and heated to 0 ^°C . 2N aqueous HC1 (300 ml) was added slowly to the resulting mixture, and the organic layer formed thereafter was separated. The separated organic layer was washed twice with satuated saline, dried over MgSO₄, and filtered. The organic solvent was removed from the filtrate under a reduced pressure to obtain the title compound (34.5 g; yield: 100%).

1H-NMR(300MHz, CDC1₃): δ 7.15-7.06 (1H, m), 6.94-6.86 (1H, m), 5.85-5.79 (1H, m), 5.20-5.14 (2H, m), 3.90-3.85 (1H, m), 3.82 (1H, dd, J=4.6, 18.5), 2.69 (1H, dd, J=7.9, 14.0), 2.37-2.32 (1H, m), 2.24-2.17 (1H, m), 1.86(1H, Br). Step 2: Preparation of (2S)-l-(2-azido-4-pentenyl)-2A5-trifluorobenezene

Dichloromethane (300 ml) was added to the (2R)-1 -(2,4,5- trifluorophenyl)-4-pentene-2-ol obtained in step 1, and cooled to 0°C . Triethylamine (20.4 ml) and 4-dimethylaminopyridine (DMAP) (1.57 g) were added successively to the mixture, and methansulfonyl chloride (1 1.2 ml) was added dropwise thereto for 30 min. The resulting mixture was stirred for 1 hour, water (150 ml) was added, and the organic layer formed thereafter was separated. The separated organic layer was washed twice with satuated saline, dried over MgSO₄, and filtered. The organic solvent was removed from the filtrate under a reduced pressure. The residue thus obtained was dissolved in DMF (300 ml), and NaN₃ (9.91 g) was added thereto. The resulting mixture was heated to 70 °C , stirred for 2 hours, and cooled to room temperature. And then water (150 ml) and ethyl acetate (150 ml) were added to the resulting mixture, and the organic layer formed thereafter was separated. The organic layer was washed twice with 150 ml of satuated saline, dried over MgSO₄, and filtered. The organic solvent was removed from the filtrate under a reduced pressure to obtain the title compound (31.5 g; yield: 94%).

¹H-NMR(300MHz, CDC1₃): δ 7.11-7.02 (1H, m), 7.97-6.87 (1H, m), 5.89-5.80 (1H, m), 5.23-5.17 (1H, m), 3.63-3.59 (1H, m), 2.87 (1H, dd, J=4.7, 18.7), 2.68 (1H, dd, J=7.9, 13.7), 2.38-2.17 (2H, m). Step 3: Preparation of (3R)-3-azido-4-(2A5-trifluorophenyl)-butyric acid

Acetonitril (300 ml) and water (300 ml) were added to the (2S)-l-(2- azido-4-pentenyl)-2,4,5-trifluorobenezene obtained in step 2, and cooled to 0°C . RuCl₃ (0.5 g) and NaIO₄ (93 g) were added to the mixture successively, and stirred for 5 hours. Ethyl acetate (90 ml) was added to the resulting mixture, filtered and the organic layer formed thereafter was separated. The separated organic layer was washed with IN HC1 (300 ml), satuated aqueous Na₂S₂O₃ (300 ml) and satuated saline (300 ml), successively, dried over MgSO₄, and filtered. The organic solvent was removed from the filtrate under a reduced pressure to obtain the title compound (32.2 g; yield: 100%). 1H-NMR(300MHz, CDC1₃): 5 10.5 (1H, br), 7.17-7.05 (1H, m), 7.02-

6.87 (1H, m), 4.14-4.03 (1H, m), 2.94-2.78 (2H, m), 2.65-2.51 (2H, m).

Step 4: Preparation of (3R)-3-azido-l-(3-trifluoromethyl-5,6-dihydro-8H- [ 1 ,2,41triazolor4,3-alpyrazin-7-yl)-4-(2,4,5-trifluorophenyl)-butan- 1 -one

(3R)-3-azido-4-(2,4,5-trifluorophenyl)-buryric acid (5 g) obtained in step 3 and triazole derivative of formula (VI) (5.3 g) were added to DMF (40 ml) and water (20 ml), stirred for 15 min, and cooled to 10^°C . N- methylmorpholine (2.4 ml) was added to the mixture, stirred for 10 min, and cooled to 0 ^°C . EDC (5.6 g) was added to the resulting mixture, and stirred for 1 hour. Ethyl acetate (50 ml) and water (25 ml) were added to the resulting mixture, and the organic layer formed thereafter was separated. The separated organic layer was washed four times with 50 ml of satuated saline, dried over MgSO₄, and filtered. The organic solvent was removed from the filtrate under a reduced pressure to obtain the title compound (7.8 g; yield: 93%).

1H-NMR(300MHz, CDC1₃): δ 7.20-7.11 (1H, m), 6.99-6.90 (1H, m), 5.20-4.96 (2H, m), 4.28-4.05 (5H, m), 2.98-2.67 (4H, m).

Step 5: Preparation of sitagliptin

(3R)-3-azido- 1 -(3-trifluoromethyl-5,6-dihydro-8H-[ 1 ,2,4]triazolo[4,3- a]pyrazin-7-yl)-4-(2,4,5-trifluorophenyl)-butan-l-one (6.4 g) obtained in step 4 and triphenylphosphin (4.3 g) were dissolved in THF (74 ml), heated to 50 ^°C , and stirred for 2 hours. An aqueous NH₄OH (37 ml) was added to the resulting mixture and stirred for 10 hours. THF was removed from the resulting mixture under a reduced pressure, HCl (30 ml) and ethyl acetate (60 ml) were added threreto, and stirred. The water layer separated from the mixture was washed twice with 30 ml of n-hexane, satuated sodium bicarbonate was added to the water layer, and extracted three times with 60 ml of ethyl acetate. The resulting extracts were dried over MgSO₄, and filtered. The organic solvent was removed from the filtrate under a reduced pressure to obtain the title compound (5.2 g; yield: 86%).

1H-NMR(300MHz, CDC1₃): δ 7.14-7.06 (1H, m), 7.00-6.88 (1H, m), 5.13-4.88 (2H, m), 4.24-3.80 (4H, m), 3.58 (1H, m), 2.85-2.66 (2H, m), 2.61-2.46 (2H, m), 2.11 (3H, br).

ABOVE IS ONLY ONE EXAMPLE LEADING TO SITAGLIPTIN

DRUG APPROVALS BY DR ANTHONY MELVIN CRASTO …..FOR BLOG HOME CLICK HERE

(S)-Sitagliptin……….Synfacts by Thieme

For description see at synfacts

https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0033-1340505

Contributor: Philip Kocienski

Philip Kocienski, Professor of Organic Chemistry.

https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0033-1340505

Bao H, Bayeh L, Tambar UK * The University of Texas Southwestern Medical Center at Dallas, USA
Catalytic Enantioselective Allylic Amination of Olefins for the Synthesis of ent-Sitagliptin.

Synlett 2013;
24: 2459-2463

P. J. Kocienski
School of Chemistry
University of Leeds
Leeds LS2 9JT, UK
p.kocienski@chem.leeds.ac.uk
http://www.chem.leeds.ac.uk

Philip J. Kocienski was born in Troy, New York, in 1946. His love for organic chemsitry, amply stimulated by Alfred Viola whilst an undergraduate at Northeastern University, was further developed at Brown University, where he obtained his PhD degree in 1971 under Joseph Ciabattoni. Postdoctoral study with George Büchi at MIT and later with Basil Lythgoe at Leeds University, England, confirmed his interest in the synthesis of natural products. He was appointed Brotherton Research lecturer at Leeds in 1979 and Professor of Chemistry at Southampton University in 1985. In 1990 he was appointed Glaxo Professor of Chemistry at Southampton University. He moved to the University of Glasgow in 1997, where he was Regius Professor of Chemistry and now he is a Professor of Chemistry at Leeds University.

In addition to Prof. Kocienski’s work as an author he is also a member of the SYNTHESIS Editorial Board and contributes greatly to the development of Thieme Chemistry’s journals

Furthermore, Prof. Kocienski has also contributed to the Science of Synthesis project where he was an author for Volume 4, Compounds of Group 15 (As, Sb, Bi) and Silicon Compounds.

Prof. Kocienski is also responsible for compiling a database called Synthesis Reviews. This resource is free and contains 16,257 English review articles (from journals and books) of interest to synthetic organic chemists. It covers literature from 1970 to 2002.

SITAGLIPTIN……………..

GREENING UP DRUGS Merck process chemists redesigned and significantly shortened the original synthesis of type 2 diabetes drug candidate sitagliptin (Januvia) to include an unprecedented efficient hydrogenation of an unprotected enamine.

MERCK was selected for the award in the greener synthetic pathways category for revising the synthesis for sitagliptin, a chiral β-amino acid derivative that is the active ingredient in Januvia, the company’s pending new treatment for type 2 diabetes. The breakthrough leading to the new synthesis was the discovery that the amino group of the key enamine intermediate doesn’t need to be protected prior to enantioselective catalytic hydrogenation of the double bond.

This development has solved a long-standing problem in the synthesis of β-amino acid derivatives, which are known for their pharmacological properties and are commonly used as chiral building blocks, noted Karl B. Hansen, a Merck process chemist involved with the synthetic effort. The outcome has been to slash the number of reaction steps in the sitagliptin synthesis from eight to three, leading to an equally dramatic reduction in the amount of chemicals and solvent needed and the amount of waste generated.

Merck’s first-generation synthesis of sitagliptin involved preparing a β-hydroxy carboxylic acid, which was converted to a protected β-lactam and then coupled to a triazole building block. Deprotecting the resulting intermediate provided the β-amino acid moiety, and sitagliptin was isolated as a phosphoric acid salt.

This synthesis involved a roundabout route involving four steps to introduce the pivotal chiral amino group of sitagliptin. The synthesis worked well to prepare more than 100 kg of the compound for clinical trials, and with modifications it was deemed to be a viable though not very green manufacturing process, Hansen pointed out. For example, the original synthesis required a number of distillations and aqueous extractions to isolate intermediates, leading to a large volume of waste to treat.

“Being environmentally friendly and economically savvy can, and does, go hand-in-hand.”

Merck process chemists recognized that a much more efficient process was possible by synthesizing the β-amino acid portion of the molecule directly from an enamine. But the protection-deprotection of the amine nitrogen with an acyl group during the hydrogenation is difficult on a large scale, and unprotected reactions generally result in lower yields and lower enantiomeric excesses, Hansen said.

Undaunted, the Merck scientists working on the revised synthesis discovered that the amino group could be efficiently introduced by an unprotected hydrogenation using a rhodium catalyst with a ferrocenyl phosphine ligand named Josiphos (C&EN, Sept. 5, 2005, page 40). Merck turned to Solvias, a Swiss company with experience in asymmetric hydrogenations that manufactures Josiphos, as a partner to help speed up the process development.

The new synthesis involves first coupling trifluorophenyl acetic acid and triazole building blocks to form a diketoamide, which in turn is converted to the enamine. This sequence is carried out without isolating intermediates. The enamine is then hydrogenated, sitagliptin is isolated and recrystallized as the phosphoric acid salt, and the rhodium Josiphos catalyst is recovered.

In sum, the revised synthesis increases the overall yield of sitagliptin by nearly 50% and reduces the amount of waste by more than 80%. A key difference is that the original synthesis produced more than 60 L of aqueous waste per kg of product, while the new synthesis completely eliminates aqueous waste. When tallied up, Merck expects these savings will prevent formation of 150,000 metric tons of solid and aqueous process waste over the lifetime of Januvia. Industry analysts speculate that regulatory approval of the drug will come by early next year and that it’s destined to become a top-selling drug.

The novel enamine hydrogenation “is arguably the most efficient means to prepare β-amino acid derivatives,” noted R. P. (Skip) Volante, Merck’s vice president of process research. The company currently is using the procedure to make several other exploratory drug candidates, he added. Overall, the redesigned synthesis of sitagliptin “is a green chemistry solution to the preparation of a challenging synthetic target and is an excellent example of a scientific innovation resulting in benefits to the environment,” Volante said.

First generation route to sitagliptin. BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl; EDC = N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride; DIAD = di-isopropyl azodicarboxylate; NMM = N-methylmorpholine……..http://www.technology.matthey.com/article/55/2/135-139/

http://pubs.rsc.org/en/content/articlelanding/2011/cc/c1cc11592h#!divAbstract

http://www.nature.com/nature/journal/v485/n7397/fig_tab/nature11117_F4.html

PAPER

SITAGLIPTIN……………..

First Generation Process for the Preparation of the DPP-IV Inhibitor Sitagliptin

Karl B. Hansen ,* Jaume Balsells , Spencer Dreher , Yi Hsiao , Michele Kubryk ,Michael Palucki , Nelo Rivera ,Dietrich Steinhuebel , Joseph D. Armstrong III,David Askin , and Edward J. J. Grabowski

Department of Process Research, Merck Research Laboratories, Rahway, New Jersey 07065, U.S.A.

Org. Process Res. Dev., 2005, 9 (5), pp 634–639

DOI: 10.1021/op0500786

http://pubs.acs.org/doi/full/10.1021/op0500786

A new synthesis of sitagliptin (MK-0431), a DPP-IV inhibitor and potential new treatment for type II diabetes, suitable for the preparation of multi-kilogram quantities is presented. The triazolopyrazine fragment of sitagliptin was prepared in 26% yield over four chemical steps using a synthetic strategy similar to the medicinal chemistry synthesis. Key process developments were made in the first step of this sequence, the addition of hydrazine to chloropyrazine, to ensure its safe operation on a large scale. The beta-amino acid fragment of sitagliptin was prepared by asymmetric reduction of the corresponding beta-ketoester followed by a two-step elaboration to an N-benzyloxy beta-lactam. Hydrolysis of the lactam followed by direct coupling to the triazolopiperazine afforded sitagliptin after cleavage of the N-benzyloxy group and salt formation. The overall yield was 52% over eight steps.

The synthesis of 1 was completed using a four-step through-process (Scheme 4). Lactam 5 or ester 13 was hydrolyzed to amino acid 2bwith LiOH¹⁸ in THF/water by either stirring at room temperature or, in the case of 13, heating to 40 °C. While the benzyloxy group of 2b could be cleaved by hydrogenation and then protected with Boc₂O to prevent side reactions during the coupling to triazole 3, the benzyloxy group of 2b was found to sufficiently protect the amino group to allow the desired amide to be formed. Thus, triazole 3 was coupled to2b at 0 °C using EDC−HCl and N-methylmorpholine (NMM) as base to afford 14in >99% assay yield. Following an aqueous workup, the organic extracts were distilled into ethanol and the solution was subjected to hydrogenation with 10% Pd on carbon. The presence of water in the hydrogenation was found to be crucial to the reaction success; anhydrous solutions of 14 hydrogenated with dry Pd on carbon proceeded only to low levels of conversion to 1, and addition of water to these reductions resulted in restored performance of the catalyst. Following hydrogenation, the catalyst was removed by filtration to provide an ethanol solution of 1. Sitagliptin was isolated in >99.5% purity as its anhydrous phosphoric acid salt by crystallizing from aqueous ethanol.

PATENT

http://www.google.co.in/patents/WO2003004498A1?cl=en

Scott D Edmondson, Michael H Fisher,Dooseop Kim, Malcolm Maccoss, Emma R Parmee, Ann E Weber, Jinyou Xu

MORE INFO………

Sitagliptin phosphate monohydrate, a dipeptidyl-peptidase IV inhibitor, is marketed by Merck & Co. for the once-daily oral treatment of type 2 diabetes. The product was first launched in Mexico followed by commercialization in the U.S. The compound has also been filed for approval in the U.S. as adjunct to diet and exercise and in combination with other therapies to improve glycemic control in the treatment of diabetes. In 2007, the product was approved by the European Medicines Evaluation Agency (EMEA) and is currently available in the U.K., Germany and Spain. In 2009, sitagliptin phosphate monohydrate was approved and launched in Japan. The product is also available in Japan for the treatment of type 2 diabetes in combination with alpha-glucosidase inhibitors and in combination therapy with insulin. In 2012, the company filed for approval in Japan for the treatment of type 2 diabetes in patients with severe renal dysfunction, and in 2013 obtained the approval.

Sitagliptin phosphate monohydrate boasts a much lower risk of hypoglycemia than currently available insulin-inducing products due to its novel mechanism of action. MSD KK (formed in 2010 following the merger of Banyu and Schering-Plough KK) and Ono are developing the drug candidate in Japan. In 2008, the compound was licensed to Almirall by Merck Sharp & Dohme for comarketing in Spain for the treatment of type 2 diabetes. In 2010, FAES obtained a comarketing and commercialization license from Merck Sharp & Dohme in Spain for the treatment of type 2 diabetes.

Januvia (sitagliptin phosphate) is an antihyperglycaemic drug containing an orally active inhibitor of the dipeptidyl peptidase-IV (DPP-IV) enzyme. Developed by Merck Sharp & Dohme (MSD), a UK subsidiary of Merck & Co, sitagliptin is used for treating type 2 diabetes mellitus. The drug has proved effective in lowering blood sugar levels of diabetes patients when taken alone or in combination with other oral diabetes medications such as metformin and thiazolidinedione.

Sitagliptin was approved by the US Food and Drug Administration (FDA) in October 2006 and is marketed under the brand name Januvia in the US. Sitagliptin in combination with metformin was approved by the FDA in March 2007 and is marketed as Janumet in the US. In the EU, Januvia was approved in April 2007 and Janumet was approved in July 2008.

Sitagliptin is a triazolopiperazine based inhibitor of DPP-IV, which was discovered by
Merck. It is a potent (IC50= 18 nM) and highly selective over DPP-8 (48000 nM), DPP-9
(>100000 nM) and other isozymes.[16] It enhances the pancreatic β-cell functions, fasting and
post-prandial glycemic control in type 2 diabetic patients. In the crystal structure with DPP-IV,
unlike other substrate-based DPP-IV inhibitors, the binding orientation of the amide carbonyl of
sitagliptin is reversed, i.e. the aromatic trifluorophenyl moiety occupies S1 pocket and the β-
amino amide moiety fits into S2 pockets. The amino group forms a salt bridge and hydrogen
bonding interactions with Glu205 and Glu206, and Tyr662, respectively.The triazolopiperazinemoiety occupies the S2 extended pocket and stacks against Phe357. The exhibited binding
interactions of the trifluoromethyl group with the Arg358 and Ser209 are responsible for its high
selectivity profile. The presence of the trifluoromethyl group in the triazole ring also improves
the oral bioavailability in animal models. Sitagliptin inhibited the plasma DPP-IV up to 80% and
47% at 2 and 24 h, respectively, after a single dose of 25.0 mg in a dose-dependent manner. In a
24-week study, sitagliptin significantly decreased fasting glucose levels and HbA1c levels
(0.8%) at doses of 100 mg q.d. Thus, sitagliptin is well tolerated and body weight neutral. It is
the first DPP-IV inhibitor in the class approved by USFDA in 2006 and is used as either a
monotherapy or in combination with metformin

In the first synthetic approach, the synthesis of sitagliptin was started with the reaction of a Schollkopf reagent 6 with 2,4,5-trifluorobenzyl bromide to afford the compound 7, which was converted to compound 9 via hydrolysis of ester 8. The resulting Boc-protected amino acid 9 was converted to diazoketone 11 through mix anhydride protocol by using diazomethane. The intermediate 11 was converted to desired β-amino acid 12 by sonication in the presence of silver benzoate.[21] The sitagliptin (14) was synthesized by coupling of β-amino acid 12 with triazolopiperazine intermediate 5 followed by Boc deprotection of amino group of 13, and its corresponding hemi fumarate salt was then prepared (Scheme 1).[16]

SYN1

The second approach for synthesis of sitagliptinwas started from asymmetric reduction of β-ketoester 15 using the (S)-BinapRuCl2 complex with a catalytic amount of HBr in methanol followed by hydrolysis afforded the β-hydroxy acid 16. Lactam 17 was synthesized by coupling of 16 with BnONH2 •HCl using N-(3- dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC), followed by cyclization reaction with diisopropyl azodicarboxylate (DIAD) and PPh3 . [22] Treatment of a catalytic amount of 0.1% NaOH with lactam 17 hydrolyzed and directly afforded the β-amino acid 18. This wascoupled withtriazolopiperazine 5 using EDC•HCl and N-methylmorpholine to provide the N-benzyloxy protected compound 19, which after hydrogenation using Pd/C and by consequent treatment with phosphoric acid provided the phosphate salt of sitagliptin (14) (Scheme 2).

SYN2

The third approach towards the synthesis of sitagliptin is outlined in scheme 3. Meldrum adduct 22 (Hunig’s base salt) was synthesized from trifluorophenylacetic acid 20 by the formation of a mixed anhydride with pivaloyl chloride in the presence of Meldrum’s acid 21, DIPEA and catalytic amount of dimethylamino pyridine (DMAP) in acetonitrile. Treatment of 22 with TFA resulted compound 23. β-keto amide 24 was formed on reaction of 23 with triazolopiperazine 5. β-keto amide 24 on treatment with ammonium acetate in methanol formed a key intermediate, dehydrositagliptin 25 (enamine amide). This intermediate contains the entire structure of sitagliptin 14 except two hydrogen atoms. Thus, sitagliptin 14 was synthesized by enantioselective hydrogenation of dehydrositagliptin 25 in the presence of [Rh(COD)2 OTf] 12,13 and t Bu JOSIPHOS in excellent yield with 95% ee.[23,24]

SYN3

http://www.cbijournal.com/paper-archive/may-june-2014-vol-3/Review-Paper-1.pdf

P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent.

REF

http://www.apiindia.org/medicine_update_2013/chap88.pdf

http://www.cbijournal.com/paper-archive/may-june-2014-vol-3/Review-Paper-1.pdf

////////////

DRUG APPROVALS BY DR ANTHONY MELVIN CRASTO …..FOR BLOG HOME CLICK HERE

Understand NMR with simple molecules, Ethyl (E)-2-butenoate

Uncategorized Comments Off

Jul 052015

Ethyl (E)-2-butenoate

Ethyl trans-crotonate

NO BAK BAK ALL PICTURES

PICTURES IN PLENTY

1H NMR

Ethyl (E)-2-butenoate

1H NMR WITH INTEGRALS

Ethyl-2-butenoate

1H-NMR proton decoupled spectrum of Ethyl-2-butenoate in CDCl3.

1H-NMR proton coupled spectrum of Ethyl-2-butenoate in CDCl3.

13C NMR

APT

image of ethyl trans-crotonate

DEPT

13C-NMR proton decoupled spectrum of Ethyl-2-butenoate in CDCl3.

DEPT spectrum of Ethyl-2-butenoate

COSY spectra

The information on the H that are coupling with each other is obtained by looking at the peaks inside the grid. These peaks are usually shown in a contour type format, like height intervals on a map.
In order to see where this information comes from, let’s consider an example shown below, the COSY of ethyl 2-butenoate
First look at the peak marked A in the top left corner. This peak indicates a coupling interaction between the H at 6.9 ppm and the H at 1.8 ppm. This corresponds to the coupling of the CH3 group and the adjacent H on the alkene.
Similarly, the peak marked B indicates a coupling interaction between the H at 4.15 ppm and the H at 1.25 ppm. This corresponds to the coupling of the CH2 and the CH3 in the ethyl group.
Notice that there are a second set of equivalent peaks, also marked A and Bon the other side of the diagonal.

(COSY spectra recorded by D. Fox, Dept of Chemistry, University of Calgary on a Bruker Advance DRX-400 spectrometer)

HETCOR spectra

The information on how the H are C are matched is obtained by looking at the peaks inside the grid. Again, these peaks are usually shown in a contour type format, like height intervals on a map.
In order to see where this information comes from, let’s consider an example shown below, the HETCOR of ethyl 2-butenoate.
First look at the peak marked A near the middle of the grid. This peak indicates that the H at 4.1 ppm is attached to the C at 60 ppm. This corresponds to the -OCH2- group.
Similarly, the peak marked B towards the top right in the grid indicates that the H at 1.85 ppm is attached to the C at17 ppm. Since the H is a singlet, we know that this corresponds to the CH3- group attached to the carbonyl in the acid part of the ester and not the CH3- group attached to the -CH2- in the alcohol part of the ester.
Notice that the carbonyl group from the ester has no “match” since it has no H attached in this example.

(HETCOR spectra recorded by D. Fox, Dept of Chemistry, University of Calgary on a Bruker Advance DRX-400 spectrometer)

HETCOR

COSY

HMQC

HMBC

/////////

MELOGLIPTIN

diabetes, phase 2, Uncategorized Comments Off

Jul 032015

GRC 8200; 868771-57-7, EMD-675992

4-fluoro-1-[2-[[(1R,3S)-3-(1,2,4-triazol-1-ylmethyl)cyclopentyl]amino]acetyl]pyrrolidine-2-carbonitrile

4(S)-Fluoro-1-[2-[(1R,3S)-3-(1H-1,2,4-triazol-1-ylmethyl)cyclopentylamino]acetyl]pyrrolidine-2(S)-carbonitrile

GRC-8200, a dipeptidyl peptidase IV inhibitor (DPP-IV), is currently undergoing phase II clinical trials at Glenmark Pharmaceuticals and Merck KGaA for the treatment of type 2 diabetes. In 2006, the compound was licensed by Glenmark Pharmaceuticals to Merck KGaA in Europe, Japan and N. America for the treatment of type 2 diabetes, however, these rights were reaquired by Glenmark in 2008.

ALTERNATE……….

see gliptins at………….http://drugsynthesisint.blogspot.in/p/gliptin-series.html

http://organicsynthesisinternational.blogspot.in/p/gliptin-series-22.html

EVOGLIPTIN

diabetes, Phase 3 drug, Uncategorized 1 Response »

Jul 032015

ChemSpider 2D Image | Evogliptin | C19H26F3N3O3

EVOGLIPTIN
CAS: 1222102-29-5 FREE

HCL……

Dong-A Pharmaceutical. Co., Ltd, 동아제약 주식회사
2-Piperazinone, 4-((3R)-3-amino-1-oxo-4-(2,4,5-trifluorophenyl)butyl)-3-((1,1-dimethylethoxy)methyl)-, (3R)-
R)-4-((R)-3-Amino-4-(2,4,5-trifluorophenyl)-butanoyl)-3-(t-butoxymethyl)-piperazin-2-one

4-[3(R)-Amino-4-(2,4,5-trifluorophenyl)butyryl]-3(R)-(tert-butoxymethyl)piperazin-2-one hydrochloride

DA-1229

DA-1229 is a dipeptidyl peptidase IV (CD26) inhibitor currently being developed in phase III clinical studies at Dong-A for the treatment of type 2 diabetes.

In 2014, Eurofarma aquired rights for product development and commercialization in Brazil.

Evogliptin Tartrate

86…………H. J. Kim, W. Y. Kwak, J. P. Min, J. Y. Lee, T. H. Yoon, H. D. Kim, C. Y. Shin, M. K.
Kim, S. H. Choi, H. S. Kim, E. K. Yang, Y. H. Cheong, Y. N. Chae, K. J. Park, J. M.
Jang, S. J. Choi, M. H. Son, S. H. Kim, M. Yoo and B. J. Lee, Bioorg. Med. Chem. Lett.,
2011, 21 (12), 3809-3812.
[87] …………K. S. Lim, J. Y. Cho, B. H. Kim, J. R. Kim, H. S. Kim, D. K. Kim, S. H. Kim, H. J. Yim,
S. H. Lee, S. G. Shin, I. J. Jang and K. S. Yu, Br. J. Clin. Pharmacol., 2009, 68 (6), 883-
890.

Originator Dong-A Pharmaceutical
Developer Dong-A ST
Class Amides; Antihyperglycaemics; Fluorobenzenes; Piperazines; Small molecules
Mechanism of Action CD26 antigen inhibitors

Orphan Drug Status No
On Fast track No
New Molecular Entity Yes
Available For Licensing Yes – Type 2 diabetes mellitus

Highest Development Phases

Phase III Type 2 diabetes mellitus

Most Recent Events

01 Sep 2014 Phase-I clinical trials in Type-2 diabetes mellitus (In volunteers) in United Kingdom (PO)
31 Jul 2014 Phase-III clinical trials in Type-2 diabetes mellitus in South Korea (PO)
31 Jul 2014 Dong-A ST initiates enrolment in a phase I trial in patients with renal impairment in South Korea (NCT02214693)

Evogliptin Tartrate

…………………………………..

WO 2010114291

http://www.google.co.in/patents/WO2010114291A2?cl=en

Formula 1

Korea Patent Publication No. 2008-0094604 the call to the scheme, as indicated by A Ⅰ) of formula (II) beta-compound of formula 3 is already substituted heterocyclic compound having 1-hydroxy-benzotriazole group (HOBT) 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (EDC) and reacting with a tertiary amine to prepare a compound of formula (4) connected by peptide bonds; Ⅱ) beta comprises the step of reacting under acidic conditions a compound of the formula (4) – a method of manufacturing the heterocyclic compounds of the formula I having an amino group is disclosed.

– Scheme A]

(Wherein, PG is a protecting group.)

In this case, the beta of the formula (2) of Scheme A – a compound having an amino group is prepared in addition to the DPP-IV inhibitor International Publication represented by Formula 1 WO03 / 000181, WO03 / 004498, WO03 / 082817, WO04 / 007468, WO04 / 032836, WO05 / 011581, WO06 / 097175, WO07 / 077508, WO07 / 063928, WO08 / 028662 WO08 / it may be used for the production of different DPP-IV inhibitors according 087,560 and can be prepared in a number of ways.

To, the compound of Formula 2 is an example as shown in Scheme J. Med.Chem. 2005; 141, and Synthesis 1997; it can be produced by the known method described in 873.

Specifically, (2S) – (+) – 2,5- dihydro-3,6-dimethoxy-2-isopropyl-pyrazine 2,4,5-trifluoro-react with benzyl bromide and acid treatment, and then the amine an ester compound obtained by the protection reaction. Ester compounds are hydrolyzed to re-3- (2,4,5-trifluoro-phenyl) -2-amino-propionic acid tert such as isobutyl chloroformate, triethylamine or diisopropylethylamine to give the amine, and then using diazomethane to form a diazo ketone, and then may be prepared by reaction with silver benzoate. However, the reaction can be performed at low temperature (-78 ℃) or high alpha-amino acid to purchase and use, and may have a risk of problems such as the need to use large diazomethane.

To a different process for preparing a compound of Formula 2 as shown in scheme Tetrahedron: Asymmetry 2006; It is known in 2622; 205 or similarly Bioorganic & Medicinal Chemistry Letters 2007.

That is, a 1,1′-carbonyl-2,4,5 which the phenyl trifluoroacetic acid activated using the following imidazole mono-methyl words potassium carbonate is reacted with the beta-keto ester compound is prepared. This produced an enamine ester using ammonium acetate and ammonium solution, the ester compound chloro (1,5-cyclooctadiene) rhodium (I) dimer using a chiral ferrocenyl ligands I the reaction of the high-pressure hydrogen with a chiral primary amine with a beta-amino ester compound after production and can lead to hydrolysis to prepare a compound of formula (2). However, use of expensive metal catalyst has a problem that must be performed in high pressure hydrogenation.

The method for preparing a compound of Formula 2 is disclosed in International Publication No. WO 04/87650.

Specifically, 2,4,5-fluorophenyl reagent is oxalyl chloride, the acid activated acid with 2,2-dimethyl-1,3-dioxane-4,6-dione, and after the reaction of methanol and the resulting material at reflux to prepare a corresponding compound. With a selective reducing reagents which enantiomers (S) -BINAP-RuCl ₂ and hydrogen through a reaction (S) – producing a compound having coordinated to each other, it again after the decomposition, and the singer O- benzyl hydroxyl amine and the coupling reaction and the intermediate is prepared. To do this, the resulting intermediate tree azodicarboxylate and diisopropyl azodicarboxylate presence ring condensation reaction, treated with an aqueous solution of lithium hydroxide to (R) – while having the formula (II) coordinated to the amine group protected with a benzyl-O- the compound can be produced. However, the method has a problem as a whole to be prepared by the reaction yield to be low and a long processing time to perform the reaction.

Thus, the conventional known method for producing a compound of the general formula (2) has the disadvantage of using expensive reagents, or not suitable for commercial mass-production method by a long synthesis time yield is also low.

In addition, the compound represented by General Formula (3), as described in Korea Patent Publication No. 2008-0094604 call, can be prepared by way of reaction schemes.

Specifically, the starting material D- serine methyl ester is substituted by a hydroxy group when reflux again substituted by trityl chloride as methoxy groups converted to the aziridine compound.

[Scheme 3]

<Example 3> (R)-4-[(R)-3-아미노-4-(2,4,5-트리플루오로페닐)부타노일]-3-(t-부톡시메틸)피페라진-2-온(화학식 1) Preparation of the hydrochloride

Step 1: t- butyl (R)-4-[(R)-2-(t-부톡시메틸)-3-옥소피페라진-1-일]-4-옥소 – 1-(2,4,5-트리플루오로페닐)부탄-2-일카르바메이트(화학식 Preparation of 4)

2 L flask, prepared in Example 1 (R) -3-t- butoxycarbonyl-4- (2,4,5-trifluoro-phenyl) butanoate acid (Formula 2) 10.0 g of toluene was dissolved in 450 mL of bis (2,2′-benzothiazolyl) disulfide 13.0 g, was cooled and then 10.2 g triphenylphosphine was added to the reaction solution at 0 ℃. While stirring the reaction mixture was added to a solution of 0.8 mL of triethylamine in 20 mL of toluene was stirred at room temperature for 5 hours. The reaction mixture was cooled to 0 ℃ and prepared in Example 2 (R) -3- (t- butoxymethyl) piperazin-2-one (Formula 3) was dissolved in 5.6 g of toluene and 40 mL pyridine a 2.4 mL was added slowly. After 30 minutes the reaction mixture was heated to room temperature and stirred for 1 hour. Saturated sheet to be the aqueous acid solution to a pH of 2.5 and then diluted with ethyl acetate 400 mL. Washed twice with brine and the organic layer was dehydrated with magnesium sulfate and concentrated. The residue was purified by column chromatography to give the title compound 838 mg.

¹ H NMR (400 MHz, CDCl ₃₎ δ 7.03 (m, 1H), 6.88 (m, 1H), 5.97 (m, 1H), 5.48 (m, 1H), 4.16 ~ 4.07 (m, 1H), 4.02 ~ 3.91 (m, 1H), 3.74 (m, 2H) 3.37 (m, 2H), 3.24 (m, 1H), 2.92 (m, 2H), 2.80 (m, 1H), 2.59 (m, 2H), 1.34 ( d, 9H), 1.13 (s, 9H)

Step 2: (R) -4 – [(R) -3- amino-4- (2,4,5-trifluoro-phenyl) butane five days] -3- (t- butoxymethyl) piperazin-2- on the production of (I) hydrochloride

Prepared in Step 1 t- butyl (R)-4-[(R)-2-(t-부톡시메틸)-3-옥소피페라진-1-일]-4-옥소-1-(2,4,5-트리플루오로페닐)부탄-2-일카르바메이트 97 mg was dissolved in methanol was added 3 mL 2N- hydrochloric acid / diethyl ether 2 mL was stirred at room temperature for 3 hours. The reaction mixture was concentrated and dried under reduced pressure to give 64 mg of the title compound as a foaming solid.

¹ H NMR (400 MHz, CD ₃ OD) δ 7.37 (m, 1H), 7.23 (m, 1H), 4.80 (m, 1H), 4.59 ~ 4.40 (m, 1H), 3.93 (m, 1H), 3.90 ~ 3.83 (m, 2H), 3.70 (m, 1H), 3.38 (m, 2H), 3.27 (m, 1H), 3.07 (m, 2H), 2.89 ~ 2.66 (m, 2H), 1.18 (s, 3H ), 1.11 (s, 6H)

Mass (M + 1): 402

<Example 4> (R)-4-[(R)-3-아미노-4-(2,4,5-트리플루오로페닐)부타노일]-3-(t-부톡시메틸)피페라진-2-온(화학식 1) tartaric acid salts

Step 1: (R) -4 – [(R) -3- amino-4- (2,4,5-trifluoro-phenyl) butane five days] -3- (t- butoxymethyl) piperazin-2- Preparation of one (I)

Example 3 to give a compound of formula I in hydrochloride 60 mg 5% sodium hydrogen carbonate in dichloromethane was added to 10 mL of an aqueous solution / 2-propanol (4/1 (v / v)) was added to the mixed solution and extracted two times 10 mL The organic layer was dried under reduced pressure to give 55 mg of the title compound as a solid.

¹ H NMR (400 MHz, CD ₃ OD) δ 7.27 (m, 1H), 7.14 (m, 1H), 4.56 ~ 4.39 (m, 1H), 3.96 ~ 3.81 (m, 3H), 3.70 (m, 1H) , 3.46 (m, 1H), 3.43 ~ 3.32 (m, 1H), 2.83 ~ 2.65 (m, 3H), 2.58 ~ 2.40 (m, 2H), 1.16 (s, 3H), 1.11 (s, 6H)

Mass (M + 1): 402

Step 2: (R) -4 – [(R) -3- amino-4- (2,4,5-trifluorophenyl) butanoyl] -3- (t- butoxymethyl) piperazin-2- one (I) tartaric acid salt [

Was dissolved 55 mg of the compound of step 1 in 0.56 mL of acetone, L- tartrate 26 mg ethanol / water (9/1 (v / v)) was added slowly to a solution of 0.35 mL was stirred for 30 minutes. Here was added 0.56 mL of 2-propanol was stirred for 10 minutes and re-filtered to give 77 mg of the title compound as a solid.

¹ H NMR (400 MHz, CD ₃ OD) δ 7.38 (m, 1H), 7.22 (m, 1H), 4.80 (m, 1H), 4.59 ~ 4.40 (m, 1H), 4.40 (s, 2H), 3.93 (m, 1H), 3.90 ~ 3.83 (m, 2H), 3.70 (m, 1H), 3.38 (m, 2H), 3.27 (m, 1H), 3.07 (m, 2H), 2.89 ~ 2.66 (m, 2H ), 1.15 (s, 3H), 1.11 (s, 6H)

Mass (M + 1): 402

………………………………

WO 2010114292

http://www.google.com/patents/WO2010114292A2?cl=en

…………………………………

Discovery of DA-1229: a potent, long acting dipeptidyl peptidase-4 inhibitor for the treatment of type 2 diabetes
Bioorg Med Chem Lett 2011, 21(12): 3809

http://www.sciencedirect.com/science/article/pii/S0960894X11004859

A series of β-amino amide containing substituted piperazine-2-one derivatives was synthesized and evaluated as inhibitors of dipeptidyl pepdidase-4 (DPP-4) for the treatment of type 2 diabetes. As results of intensive SAR study of the series, (R)-4-[(R)-3-amino-4-(2,4,5-trifluorophenyl)-butanoyl]-3-(t-butoxymethyl)-piperazin-2-one (DA-1229) displayed potent DPP-4 inhibition pattern in several animal models, was selected for clinical development.

About evogliptin tartrate tablets

Evogliptin tartrate tablets is a dipeptidyl peptidase IV inhibitor, in tablet form. Evogliptin tartrate

tablets is expected to be approved for the treatment of type 2 diabetes mellitus. The Group holds

an exclusive intellectual property licence from Dong-A Pharmaceutical Co. Ltd. to develop

and commercialise evogliptin tartrate tablets in China, including the exclusive right to develop

evogliptin tartrate tablets for manufacturing and sale in the Group’s name. The new drug certificate

to be issued by the CFDA will be approved and registered under the Group’s name.

Evogliptin is a patented new molecular entity in the United States and other international markets.

Evogliptin tartrate tablets is being concurrently developed by Dong-A Pharmaceutical Co. Ltd.

for the Korean market. Based on information released from a multi-centre, phase II, randomised,

double-blind, placebo-controlled, therapeutic exploratory clinical trial conducted in Korea by

Dong-A Pharmaceutical Co. Ltd. to investigate the efficacy and safety of evogliptin, evogliptin

was proven to be effective in significantly lowering blood glucose levels in patients with type

2 diabetes. Data also show that the body weights of patients remain stable over the treatment

period. In addition, evogliptin was proven to be safe and well tolerated with no severe adverse

drug reactions observed during those phase II clinical trials. The Company believes evogliptin

tartrate tablets will help reduce the burden of patients with moderate-to-severe renal impairment

as pharmacokinetic study in animal model and healthy human volunteers showed low renal

elimination.

According to the statistics of IMS Health Incorporated, the market size of products for the

treatment of diabetes in China in 2013 was approximately RMB7.8 billion, and grew at a

compound annual growth rate of 23.4% from 2011 to 2013.

http://www.luye.cn/en/uploads//2014-07/21/_1405936452_zr21xh.pdf

Dong-A ST

SEOUL, SOUTH KOREA

14 April 2015 – 5:45pm

Oh Seung-mock

Dong-A ST has licensed its new diabetes drug Evogliptin to 17 Latin American countries including Mexico, Venezuela, Argentina, Chile, Colombia, Ecuador, Peru, the Dominican Republic, and Uruguay, Jung Jae-wook, Dong-A ST’s PR manager, told Business Korea.

Dong-A ST and Eurofarma, a Brazilian pharmaceutical company, concluded the licensing contract at Dong-A ST’s headquarters on April 13 in Seoul.

Eurofarma will be responsible for Evogliptin’s product development and sales in the 17 Latin American countries, Dong-A ST said. Dong-A ST will receive royalties from Eurofarma, and export the raw material of the medicine.

Dong-A ST has been developing Evogliptin with the support of the Ministry of Health & Welfare of South Korea as an innovative new medicine research project since May 2008. Evogliptin is a DPP-4 remedy based on the inhibition mechanism which is “excellent” at reducing blood sugar, whilst “less likely” to cause weight increases and hypoglycemia, the company said.

Park Chan-il, president of Dong-A ST, said that Dong-A ST will pursue further out-licensing “over the globe,” through continuous investment in research and development.

Maurizio Billi, Eurofarma’s president, wished to expand both companies’ partnership in the innovative new remedy development sector, according to Dong-A ST.

Last July, Dong-A ST and Eurofarma concluded a contract out-licensing Evogliptin to Brazil itself, the company said.

– See more at: http://www.businesskorea.co.kr/article/10115/southern-strategy-dong-st-licenses-new-diabetes-drug-evogliptin-17-latin-american#sthash.liqwFTWU.dpuf

http://www.koreaittimes.com/story/47669/%EB%8F%99%EC%95%84st-evogliptin-%EC%B6%94%EA%B0%80-%EB%9D%BC%EC%9D%B4%EC%84%BC%EC%8B%B1-%EC%95%84%EC%9B%83-%EA%B3%84%EC%95%BD-%EC%B2%B4%EA%B2%B0

see gliptins at………….http://drugsynthesisint.blogspot.in/p/gliptin-series.html

http://organicsynthesisinternational.blogspot.in/p/gliptin-series-22.html

see gliptins at…..http://drugsynthesisint.blogspot.in/p/gliptin-series.html

see gliptins at………….http://drugsynthesisint.blogspot.in/p/gliptin-series.html

http://organicsynthesisinternational.blogspot.in/p/gliptin-series-22.html

Dong-A Pharm. Co., Ltd, Yongin-si, Gyeonggi-do, Republic of Korea.

GOSOGLIPTIN

diabetes, Uncategorized 1 Response »

Jul 032015

ChemSpider 2D Image | gosogliptin | C17H24F2N6O

GOSOGLIPTIN

CAS 869490-23-3 FREE BASE

DIHYDROCHLORIDE..869490-47-1

GOSOGLIPTIN; UNII-GI718UO477; PF-00734200; PF-734200;

(3,3-difluoropyrrolidin-1-yl)-[(2S,4S)-4-(4-pyrimidin-2-ylpiperazin-1-yl)pyrrolidin-2-yl]methanone

Molecular Formula:	C17H24F2N6O
Molecular Weight:	366.408866 g/mol

Company	Pfizer Inc.
Description	Dipeptidyl peptidase-4 (DPP-4) inhibitor
Molecular Target	Dipeptidyl peptidase-4 (DPP-4) (CD26)
Mechanism of Action	Dipeptidyl peptidase-4 (DPP-4) inhibitor

Latest Stage of Development	Phase II
Standard Indication	Diabetes
Indication Details	Treat Type II diabetes

Type 2 diabetes mellitus is a chronic disorder characterized by hyperglycemia coupled with a gradual decline in insulin sensitivity and insulin secretion. The incretin hormone glucagon-like peptide-1 (GLP-1), which is released post-prandially from the L-cells of the intestine, stimulates the release of insulin from pancreatic β-cells. However, GLP-1 is rapidly degraded in vivo by peptidases, including dipeptidyl peptidase IV (DPP-4), which is a widely distributed serine protease that specifically cleaves N-terminal dipeptides from polypeptides with proline or alanine at the penultimate position.

In vivo administration of DPP-4 inhibitors to human subjects results in higher circulating concentrations of endogenous GLP-1 and subsequent decrease in plasma glucose. Long term treatment with a DPP-4 inhibitor leads to a reduction in circulating HbA1c (glycosylated hemoglobin). DPP-4 inhibition also offers the potential to improve the insulin producing function of the pancreas through either β-cell preservation or regeneration. Therefore, DPP-4 inhibition has emerged as a promising new treatment of Type 2 diabetes

PF-734200 is a potent, selective, orally active dipeptidyl peptidase IV inhibitor. It had been in phase II clinical development at Pfizer for the treatment of type 2 diabetes; however, in 2010 the company discontinued these trials. In 2012, the product was licensed to SatRx, a spin-off of the ChemRar High Tech Center, by Pfizer on an exclusive worldwide basis (with the exception of China) for the development and commercialization as monotherapy or in combination with other therapies for the treatment of type 2 diabetes. SatRx is conducting phase II clinical trials for the treatment of type 2 diabetes.

……………………….

PAPER

New synthetic route to a dipeptidyl peptidase-4 inhibitor
Org Process Res Dev 2012, 16(3): 409

http://pubs.acs.org/doi/abs/10.1021/op200309z

A new synthetic route to a dipeptidyl peptidase-4 (DPP4) inhibitor was developed and demonstrated on a multigram scale. This approach takes advantage of the cheap and readily available Boc-trans-4-hydroxy-l-proline methyl ester as starting material which was derivatized through an SN2 reaction. Several leaving groups were studied, and the nosylate group showed superiority over other derivatives. Formation of an amide using the most costly starting material, 3,3-difluoropyrrolidine, was performed late in the synthesis to minimize its economical impact on the overall cost of the API.

(3,3-Difluoropyrrolidin-1-yl)-(2S,4S)-4-(4-(pyrimidin-2-yl)piperazin-1-yl)pyrrolidin-2-yl)methanone.FREE BASE

Mp 149 °C (decomp).

[α]d = −31.1 (T = 24 °C, c = 1, CHCl3). Specific rotation of product 4 prepared using the initial route: [α]d = −31.5 (T = 24 °C, c = 1, CHCl3).

1H NMR (400 MHz; CDCl3) δ 8.30 (d, J = 4 Hz, 2H), 6.48 (t, J = 4 Hz, 1H), 3.95–3.6 (m, 9H), 3.25–2.85 (m, 4H), 2.6–2.25 (m, 7H), 1.75–1.6 (m, 1H).

13C NMR (100 MHz; CDCl3) δ 172.28; 161.55; 157.70; 127.22 (t, 1J C–F = 248 Hz), 126.22 (t, 1J C–F = 246 Hz), 109.95; 66.54; 58.87; 57.99; 52.71 (t, 2 J C–F = 32 Hz); 52.00; 50.41; 43.03; 34.46, 34.37, 34.25; 19F NMR (377 MHz, CDCl3) δ −102.1 (m, 2F).

IR (neat): 2951w, 2864w, 2799w, 2759w, 1630s, 1585vs, 1547m, 1449m, 1172m, 1254m, 1129m, 982w, 923m, 796m, 638w.

HRMS (ES, N2) Calcd for C17H24F2N6O: 367.20524, found: 367.20592.

……………………….

PAPER

(3,3-difluoro-pyrrolidin-1-yl)-((2S,4S)-(4-(4-pyrimidin-2-yl-piperazin-1-yl)-pyrrolidin-2-yl)-methanone: A potent, selective, orally active dipeptidyl peptidase IV inhibitor
Bioorg Med Chem Lett 2009, 19(7): 1991

http://www.sciencedirect.com/science/article/pii/S0960894X09001966?np=y

Pfizer Global Research & Development, Groton/New London Laboratories, Pfizer Inc, Groton, CT 06340, United States

doi:10.1016/j.bmcl.2009.02.041

A series of 4-substituted proline amides was evaluated as inhibitors of dipeptidyl pepdidase IV for the treatment of type 2 diabetes. (3,3-Difluoro-pyrrolidin-1-yl)-[(2S,4S)-(4-(4-pyrimidin-2-yl-piperazin-1-yl)-pyrrolidin-2-yl]-methanone (5) emerged as a potent (IC₅₀= 13 nM) and selective compound, with high oral bioavailability in preclinical species.

SEE………….https://docs.google.com/viewer?url=http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2FMiamiMultiMediaURL%2F1-s2.0-S0960894X09001966%2F1-s2.0-S0960894X09001966-mmc1.doc%2F271398%2Fhtml%2FS0960894X09001966%2Fce1f70bd989d6d4b79b40c26570693d2%2Fmmc1.doc

………………….

PATENT

WO 2005116014

http://www.google.co.in/patents/WO2005116014A1?cl=en

Example 113 (3.3-Difluoropyrrolidin-1-yl)-((2S,4S)-4-(4-(pyrimidin-2-yl)piperazin-1-yl)pyrrolidin-2-yl)-methanone

Step 1 – (S)-2-(3.3-Difluoro-pyrrolidine-1-carbonyl)-4-oxo-pyrrolidine-1 -carboxylic acid tert-butyl ester

3,3-Difluoro- pyrrolidine hydrochloride (4.13 kg, 1.0 equivalent) was charged to the above mixture over 10 minutes at – 10°C to 0°C. Triethylamine (4.0 liters, 1.0 equiv) was introduced slowly over 70 minutes at -10°C to 0°C. Upon completion of triethylamine addition, the mixture was stirred for 1h at 0 to 5°C. The reaction was complete by HPLC assay (-1% starting material). The reaction was quenched with water (10 volumes) at 0°C to 5 °C. The mixture was heated to 20°C to 25 °C. The layers were separated, and the organic layer was washed with 0.5 M HCI (5 volumes). The organic layer was again washed with combined 5% NaHC0₃ (2 volumes) and half saturated brine solution (1.64 M, 3 volumes). The organic solution was concentrated atmospherically to a low stirrable volume (approximately 20 liters). Ethyl acetate (12.6 volumes, 82.8 liters) was added, the solution was concentrated atmospherically to -6 volumes. The mixture was held at 60°C to 65 °C for 2 hours and cooled to room temperature over 3 hours. The mixture was held at 20°C to 25 °C for 8 hours. Heptane (8 volumes) was added, and the mixture was granulated for a minimum of 2 hours. The solid was filtered, rinsed with 2:1 heptane/ethyl acetate (1 volume), and dried in a tray dryer at 25°C to 35°C for a minimum of 12 h. Yield: 7.26 kg, 79%. HPLC purity: 99.7%. The mother liquor (86 liters) was concentrated to 12 liters under partial vacuum at 65°C to 70°C. The mixture was cooled to 60°C to 65 °C. Ethyl acetate (4.0 liters) was added slowly over 15 minutes. The mixture was cooled to 20°C to 25 °C over 2 hours and was held at that temperature for at least 2 hours. The solid was filtered and rinsed with heptane/ethyl acetate (3:1 v/v, 1.7 liters). Drying in a tray dryer for 12 hours at 35°C to 45 °C yielded 435 grams of product. HPLC purity: 96.4%.

Step 2 – (2S.4S)-2-(3.3-Dif luoro-pyrrolidine-1 -carbonyl)-4-(4-pyrimidin-2-yl-piperazin-1 -yl)-pyrrolidine-1 – carboxylic acid tert-butyl ester A reactor was charged with THF (20 volumes), 2-piperazin-1-yl-pyrimidine (2.17 kg, 1.05 equivalents) and the product from Step 1 (4.00 kg, 1.0 equivalent). The mixture was held at 20°C to 25°C until all material was dissolved over 30 minutes. Acetic acid (0.792 kg, 1.05 equivalents) as added. The mixture was stirred for 1 hour during which the reaction mixture turned to cloudy. The reaction mixture was refluxed for 30 minutes and then concentrated at 60°C to 70°C until a steady temperature of 66.9°C was observed in the overheads indicating complete removal of water from the system. More THF was added as necessary. At the end, THF was added to bring the total volume in the reactor to 15 volumes of the limit reagent. The reaction mixture was cooled to -3°C to 7°C and sampled for complete formation of imine by HPLC (using sodium triacetoxyborohydride to reduce imine). Sodium triacetoxyborohydride (5.33 kg, 2.0 equivalents) was added portion-wise to the suspension at -5°C to 15°C. The reaction mixture was heated to 20°C to 25°C and held for 12 hours. HPLC results confirmed the reaction was complete by 99.8%. Sodium bicarbonate aqueous solution (10% w/w, 10 volumes) was added. The slurry was concentrated to remove 10 volumes of THF under partial vacuum at 30°C to 60°C. Ethyl acetate (10 volumes) was added to the suspension after it cooled to 20°C to 25^CC. The organic phase was separated and the aqueous phase was checked by HPLC. It contained less than 2% of the product. The organic phase was washed with water (5 volumes), saturated brine solution (5 volumes) and concentrated to a small volume (2 volumes) under partial vacuum at 45°C to 50°C. To the slurry was added heptane (10 volumes) at 45°C to 50°C over 30 minutes. The mixture was cooled to 20°C to 25°C and granulated for 2 hours. Solid was collected by filtration, rinsed with heptane (2 volumes). Drying in a tray dryer for 12 hours at 35°C to 45°C yield 5.35 kg (91.3%) of the product. Step 3 – (3.3-Dif luoro-pyrrolidin-1 -yl)-f(2S.4S)-4-(4-pyrimidin-2-yl-piperazin-1 -yl)-pyrrolidin-2-yll- methanone Water (19 liters, 2 volumes) was charged to a reactor followed by the product from Step 2 (9.57 kg,

1.0 equivalent). To the slurry was added concentrated HCI (37 wt% in water, 19.1 liters, 2 volumes) slowly at 20°C to 30°C over 4 hours. The slurry went into solution after 12 liters of HCI was added. After the addition completion, the reaction was complete by HPLC assay. The reaction mixture was cooled to 5°C to 15°C. To the mixture was added 50% NaOH aqueous solution slowly with agitation to pH 10 to pH 11. The pH was monitored with a pH meter closely during the neutralization. The total volume of 50% NaOH added was 12.45 liters. The mixture was warmed to 20°C to 25°C and extracted with ethyl acetate twice (115 liters, 12 volumes and 57 liters, 6 volumes, respectively). The sample from aqueous layer after second extraction was analyzed by HPLC and showed only 1% of the product in that aqueous solution.

The organic layers were combined and treated with magnesium sulfate (5 kg) for 1 hour. The mixture was filtered. The filter cake was rinsed with ethyl acetate (10 liters). The filtrate was charged back to the reactor via a 0.2 micron in-line filter for speck free operation. (The following operations were performed under speck free conditions.) The solution was concentrated to 20 liters (2 volumes) under partial vacuum at 50°C to 60°C. The mixture was cooled to 20°C to 25°C over 30 minutes. Upon cooling to room temperature, crystallization occurred. The mixture was held for 30 minutes. Hexanes (20 liters, 2 volumes) was added slowly over 1 hour. The mixture was granulated for 2 hours. The solid product was collected by filtration and rinsed with hexanes/ethyl acetate (10 liters, 1 :1 v/v). The filter was blown dry with nitrogen for a minimum of 2 hours. The product was dried in a tray dryer at 44°C for 12 hours.

Yield: 5.7 kg, 75.9%.

m.p. 156°C. MS m/z 367 (MH⁺).

FREE BASE

¹H NMR (400 MHz, D₂0): δ 8.15 (d, 2H, J = 5.0 Hz, CH of pyrimidine), 6.55 (t, 1 H, J = 4.8 Hz, CH of pyrimidine), 3.87-3.81 (dd, 1 H, H_2b of proline, rotomeric), 3.78-3.50 (m, 4H, N-CH₂ of pyrrolidide), 3.55-3.40 (m, 4H, N-CH₂ of piperazine), 2.97 (dd, 1 H, J = 10.2, 6.6 Hz, H_5a of proline), 2.85-2.75 (m, 1 H, H_4b of proline), 2.69 (dd, 1 H, J = 10.0, 9.1 Hz, H_5b of proline), 2.55-2.20 (m, 7H, overlapping N-CH₂ of piperazine, CH₂ of pyrrolidide and H_3b of proline), 1.47-1.38 (m, 1 H, H_3a of proline).

Alternatively, the dihydrochloride salt of the titled compound was prepared according to the method of Example 1.

………………

US 2005/0256310

http://www.google.com/patents/US20050256310

This approach begins with N–t-Boc-4-oxo-l-proline (1) that undergoes a mixed anhydride activation with pivaloyl chloride at 0 °C, followed by amidation with 3,3-difluoropyrrolidine to yield the intermediate 2. Reductive amination with 1-(2-pyrimidyl)piperazine using sodium triacetoxyborohydride in THF/AcOH provided the desired stereoisomer 3 in high yield and selectivity, the undesired diastereomer being completely removed by crystallization. Deprotection of 3 with 6 N HCl, followed by neutralization with 50% NaOH and extraction provided PF-734200 (4) in good yield.

EXAMPLE 113 (3,3-Difluoropyrrolidin-1-yl)-((2S,4S)-4-(4-(pyrimidin-2-yl)piperazin-1-yl)pyrrolidin-2-yl)-methanone

Step 1—(S)-2-(3,3-Difluoro-pyrrolidine-1-carbonyl)-4-oxo-pyrrolidine-1-carboxylic acid tert-butyl

(S)-4-Oxo-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester (6.6 kg, 1.0 equivalent) was charged to a reactor, followed by addition of dichloromethane (15 volumes). The reaction mixture was cooled to 0° C. Triethylamine (4.82 liters, 1.2 equiv) was added over 30 minutes. The mixture turned from suspension to a clear solution at the end of triethylamine addition. The mixture was held at 0° C. to 5° C. for 10 minutes. Pivaloyl chloride (3.65 kg, 1.05 equivalents) was added slowly while keeping the reaction temperature at 0° C. to 5° C. The reaction mixture turned back to a slurry. The reaction mixture was sampled for completion by HPLC (using diethylamine to derivatize) after held for 1 hour at 0° C. to 5° C. 3,3-Difluoro-pyrrolidine hydrochloride (4.13 kg, 1.0 equivalent) was charged to the above mixture over 10 minutes at −10° C. to 0° C. Triethylamine (4.0 liters, 1.0 equiv) was introduced slowly over 70 minutes at −10° C. to 0° C. Upon completion of triethylamine addition, the mixture was stirred for 1 h at 0 to 5° C. The reaction was complete by HPLC assay (˜1% starting material). The reaction was quenched with water (10 volumes) at 0° C. to 5 ° C. The mixture was heated to 20° C. to 25 ° C. The layers were separated, organic layer was washed with 0.5 M HCl (5 volumes). The organic layer was again washed with combined 5% NaHCO₃(2 volumes) and half saturated brine solution (1.64 M, 3 volumes). The organic solution was concentrated atmospherically to a low stirrable volume (approximately 20 liters). Ethyl acetate (12.6 volumes, 82.8 liters) was added, the solution was concentrated atmospherically to ˜6 volumes. The mixture was held at 60° C. to 65° C. for 2 hours and cooled to room temperature over 3 hours. The mixture was held at 20° C. to 25 ° C. for 8 hours. Heptane (8 volumes) was added, and the mixture was granulated for a minimum of 2 hours. The solid was filtered, rinsed with 2:1 heptane/ethyl acetate (1 volume), and dried in a tray dryer at 25° C. to 35° C. for a minimum of 12 h. Yield: 7.26 kg, 79%. HPLC purity: 99.7%. The mother liquor (86 liters) was concentrated to 12 liters under partial vacuum at 65° C. to 70° C. The mixture was cooled to 60° C. to 65° C. Ethyl acetate (4.0 liters) was added slowly over 15 minutes. The mixture was cooled to 20° C. to 25° C. over 2 hours and was held at that temperature for at least 2 hours. The solid was filtered and rinsed with heptane/ethyl acetate (3:1 v/v, 1.7 liters). Drying in a tray dryer for 12 hours at 35° C. to 45° C. yielded 435 grams of product. HPLC purity: 96.4%.

Step 2—(2S,4S)-2-(3,3-Difluoro-pyrrolidine-1-carbonyl)-4-(4-pyrimidin-2-yl-piperazin-1-yl)-pyrrolidine-1-carboxylic acid tert-butyl ester

A reactor was charged with THF (20 volumes), 2-piperazin-1-yl-pyrimidine (2.17 kg, 1.05 equivalents) and the product from Step 1 (4.00 kg, 1.0 equivalent). The mixture was held at 20° C. to 25° C. until all material was dissolved over 30 minutes. Acetic acid (0.792 kg, 1.05 equivalents) as added. The mixture was stirred for 1 hour during which the reaction mixture turned to cloudy. The reaction mixture was refluxed for 30 minutes and then concentrated at 60° C. to 70° C. until a steady temperature of 66.9° C. was observed in the overheads indicating complete removal of water from the system. More THF was added as necessary. At the end, THF was added to bring the total volume in the reactor to 15 volumes of the limit reagent. The reaction mixture was cooled to −3° C. to 7° C. and sampled for complete formation of imine by HPLC (using sodium triacetoxyborohydride to reduce imine). Sodium triacetoxyborohydride (5.33 kg, 2.0 equivalents) was added portion-wise to the suspension at −5° C. to 15° C. The reaction mixture was heated to 20° C. to 25° C. and held for 12 hours. HPLC results confirmed the reaction was complete by 99.8%. Sodium bicarbonate aqueous solution (10% w/w, 10 volumes) was added. The slurry was concentrated to remove 10 volumes of THF under partial vacuum at 30° C. to 60° C. Ethyl acetate (10 volumes) was added to the suspension after it cooled to 20° C. to 25° C. The organic phase was separated and the aqueous phase was checked by HPLC. It contained less than 2% of the product. The organic phase was washed with water (5 volumes), saturated brine solution (5 volumes) and concentrated to a small volume (2 volumes) under partial vacuum at 45° C. to 50° C. To the slurry was added heptane (10 volumes) at 45° C. to 50° C. over 30 minutes. The mixture was cooled to 20° C. to 25° C. and granulated for 2 hours. Solid was collected by filtration, rinsed with heptane (2 volumes). Drying in a tray dryer for 12 hours at 35° C. to 45° C. yield 5.35 kg (91.3%) of the product.

Step 3—(3,3-Difluoro-pyrrolidin-1-yl)-[(2S,4S)-4-(4-pyrimidin-2-yl-piperazin-1-yl)-pyrrolidin-2-yl]-methanone

Water (19 liters, 2 volumes) was charged to a reactor followed by the product from Step 2 (9.57 kg, 1.0 equivalent). To the slurry was added concentrated HCl (37 wt % in water, 19.1 liters, 2 volumes) slowly at 20° C. to 30° C. over 4 hours. The slurry went into solution after 12 liters of HCl was added. After the addition completion, the reaction was complete by HPLC assay. The reaction mixture was cooled to 5° C. to 15° C. To the mixture was added 50% NaOH aqueous solution slowly with agitation to pH 10 to pH 11. The pH was monitored with a pH meter closely during the neutralization. The total volume of 50% NaOH added was 12.45 liters. The mixture was warmed to 20° C. to 25° C. and extracted with ethyl acetate twice (115 liters, 12 volumes and 57 liters, 6 volumes, respectively). The sample from aqueous layer after second extraction was analyzed by HPLC and showed only 1% of the product in that aqueous solution. The organic layers were combined and treated with magnesium sulfate (5 kg) for 1 hour. The mixture was filtered. The filter cake was rinsed with ethyl acetate (10 liters). The filtrate was charged back to the reactor via a 0.2 micron in-line filter for speck free operation. (The following operations were performed under speck free conditions.) The solution was concentrated to 20 liters (2 volumes) under partial vacuum at 50° C. to 60° C. The mixture was cooled to 20° C. to 25° C. over 30 minutes. Upon cooling to room temperature, crystallization occurred. The mixture was held for 30 minutes. Hexanes (20 liters, 2 volumes) was added slowly over 1 hour. The mixture was granulated for 2 hours. The solid product was collected by filtration and rinsed with hexanes/ethyl acetate (10 liters, 1:1 v/v). The filter was blown dry with nitrogen for a minimum of 2 hours. The product was dried in a tray dryer at 44° C. for 12 hours.

Yield: 5.7 kg, 75.9%. m.p. 156° C. MS m/z 367 (MH⁺).

¹H NMR (400 MHz, D₂O): δ 8.15 (d, 2H, J=5.0 Hz, CH of pyrimidine), 6.55 (t, 1H, J=4.8 Hz, CH of pyrimidine), 3.87-3.81 (dd, 1H, H_2bof proline, rotomeric), 3.78-3.50 (m, 4H, N—CH₂of pyrrolidide), 3.55-3.40 (m, 4H, N—CH₂of piperazine), 2.97 (dd, 1H, J=10.2, 6.6 Hz, H_5aof proline), 2.85-2.75 (m, 1H, H_4bof proline), 2.69 (dd, 1H, J=10.0, 9.1 Hz, H_5bof proline), 2.55-2.20 (m, 7H, overlapping N—CH₂of piperazine, CH₂of pyrrolidide and H_3bof proline), 1.47-1.38 (m, 1H, H_3aof proline).

Alternatively, the dihydrochloride salt of the titled compound was prepared according to the method of Example 1.

……………..

PAPER

Scheme 1.

Reagents and conditions: (a) 3,3-difluoropyrrolidine hydrochloride, EDC, HOBt, TEA, DCM, rt; (b) NaBH₄, MeOH, (c) (1) trifluoromethane-sulphonyl chloride, DIPEA, DCM; (2) 2-(1-piperazinyl)pyrimidine, DCM, −10 °C; (d) 4 N HCl in dioxane, rt; (e) 2-(1-piperazinyl)pyrimidine, NaBH(OAc)₃, AcOH, DCE; (f) R₁R₂NH hydrochloride, EDC, HOBt TEA, DCM, 0–rt; (g) N-heterocyclic piperazine, NaBH(OAc)_3, AcOH, DCE.

……………………….

Patent	Submitted	Granted
Therapeutic compounds [US7291618]	2005-11-17	2007-11-06
(2S,4S)-4-(piperazin-1-yl)pyrrolidine-2-methanone derivatives [US7465732]	2007-05-03	2008-12-16
THERAPEUTIC COMPOUNDS [US2007161664]	2007-07-12
Therapeutic compounds [US2006079498]	2006-04-13

see gliptins at………….http://drugsynthesisint.blogspot.in/p/gliptin-series.html

http://organicsynthesisinternational.blogspot.in/p/gliptin-series-22.html

see gliptins at…………http://drugsynthesisint.blogspot.in/p/gliptin-series.html

TENELIGLIPTIN

diabetes, Uncategorized 1 Response »

Jul 032015

TENELIGLIPTIN

Teneligliptin; 760937-92-6; UNII-28ZHI4CF9C; Teneligliptin (INN); 28ZHI4CF9C
MF	C22H30N6OS
MW	426.5782 g/mol

Teneligliptin (INN; trade name Tenelia) is a pharmaceutical drug for the treatment of type 2 diabetes mellitus. It is approved for use in Japan.^[1] It belongs to the class of anti-diabetic drugs known as dipeptidyl peptidase-4 inhibitors or “gliptins”.^[2] {(2S,4S)-4-[4-(3-Methyl-1-phenyl-1H-pyrazol-5-yl)-1-piperazinyl]-2-pyrrolidinyl}(1,3-thiazolidin-3-yl)methanone

Teneligliptin was launched in Japan in 2012 by Mitsubishi Pharma and Daiichi Sankyo for the treatment of type 2 diabetes mellitus. In 2013, the indication was partially changed to include it as a combination therapy with existing oral hypoglycemic agents, such as biganides, alpha-glucosidaseinhibitors, rapid-acting insulin secretagogues, and insulin preparations, as well as sulfonylureas and thiazolidines that had been approved for the combination.

In 2014, the product was registered in KR for the treatment of type 2 diabetes mellitus.
In 2013, Mitsubishi Tanabe Pharma filed for approval in Japan for use of the compound as combination therapy for the treatment of diabetes type 2.

CAS	760937-92-6

3-{(2S,4S)-4-[4-(3-methyl-l -phenyl- 1 H- pyrazol-5-yl)- l-piperazinyl]-2-pyrrolidinylcarbonyl}-l , 3-thiazolidine is represented structurally by a compound of formula (I):

Teneligliptin (CAS 760937-92-6) is a novel, potent and long-lasting dipeptidyl peptidase-4 inhibitor in treatment of type 2 diabetes. Dipeptidyl-peptidase-4 (DPP- 4) inhibitor has been demonstrated to improve glycemic control, in particular postparandial hyperglycemic control.

Despite of their common mechanism of action, DPP-4 inhibitors show marked structural heterogeneity. DPP-4 inhibitors may be classified into peptidomimetic (i.e. sitagliptin, vildagliptin, saxagliptin, and anagliptin) and non-peptidomimetic (i.e. alogliptin and linagliptin) subtypes.

Teneligliptin, is chemically known as a 3- {((2S,4S)-4-(4-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazin-1-yl)pyrrolidin-2-yl 25 carbonyl}thiazolidine hemipentahydrobromide hydrate and is peptidomimetic with the molecular formula of C22H30N6OS.2½HBr.xH2O and molecular weight of 642.88 g/mol for hemipentahydrobromide. The hydrate can be from mono to dihydrate.

U.S. Patent No. 7,074,794 B2 (the US ‘794) discloses teneligliptin as L-proline derivative and its pharmaceutically acceptable salts which exhibits a Dipeptidyl 5 peptidase IV (DPP-IV) inhibitory activity, which is useful for the treatment or prophylaxis of diabetes, obesity, HIV infection, cancer metastasis, dermopathy, prostatic hyperplasia, periodontitis, autoimmune diseases and the like.

The example-222 of the US ‘794 discloses the process for the preparation of teneligliptin as trihydrochloride salt U.S. Patent No. 8,003,790 B2 (the US ‘790) discloses salts of proline derivative, solvate thereof and production method thereof. In particular, the US ‘790 discloses 2.0 hydrochloride or 2.5 hydrochloride; 2.0 hydrobromide or 2.5 hydrobromide, and hydrates thereof teneligliptin.

The US ‘790 B2 further discloses different salts 15 of teneligliptin which are incorporated herein as reference in their entirety U.S. PG-Pub. No. 2011/0282058 A1 discloses salts of 3-{((2S,4S)-4-(4-(3-methyl- 1-phenyl-1H-pyrazol-5-yl)piperazin-1-yl)pyrrolidin-2-ylcarbonyl}thiazolidine with mono-, di- and tri-basic acids or a solvate thereof. 20 International (PCT) publication No. WO 2012/165547 A1 discloses a process for preparation of teneligliptin and pharmaceutically acceptable salts thereof.

International (PCT) publication No. WO 2007/127635 A2 (the WO ‘635 A2) discloses a process for the preparation of diketo-piperazine and piperidine 25 derivatives. In particular, the WO ‘635 A2 discloses the process for preparation of 4-oxo-2-(thiazolidine-3-carbonyl)-pyrrolidine-1-carboxylic acid tert-butyl ester [herein compound (III)] by reacting piperazine with aryl halide.

International (PCT) publication No. WO 2012/099915 A1 (the WO ‘915 A1) 5 discloses the process for the preparation of deuterated thiazolidine derivatives. The WO ‘915 A1 also discloses the process for the preparation of 1-(3-methyl-1- phenyl-1H-pyrazol-5-yl)piperazine herein compound (V) by condensation of 5- chloro-3-methyl-1-phenyl-1H-pyrazole with piperazine.

Bioorganic & Medicinal Chemistry, 20(19), 5705-5719 (2012) discloses the process for the preparation of 1-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazine herein compound (V) by deprotection of Boc-protected 1-(3-methyl-1-phenyl-1Hpyrazol-5-yl)piperazine with triflouroacetic acid.

U.S. Patent Nos. 7,807,676 B2 and 7,807,671 B2 discloses a process for the preparation of 1-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazine by condensation of 5-chloro-3-methyl-1-phenyl-1H-pyrazole with piperazine in presence of n-BuLi in tetrahydrofuran. Bioorganic & Medicinal Chemistry, 14(11), 3662-3671 (2006),

Bioorganic & Medicinal Chemistry, 20(16), 5033-5041 (2012) and U.S. Patent Nos. 7,807,676 B2 and 7,807,671 B2 discloses a process for the preparation of (2S,4R)-tert-butyl 4-hydroxy-2-(thiazolidine-3-carbonyl)pyrrolidine-1-carboxylate by reacting (2S,4R)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid with 25 thiazolidine in presence of HOBT and EDC.HCl in dimethylformamide solvent.

Bioorganic & Medicinal Chemistry, 15(2), 641-655 (2007) discloses a process for the preparation of (2S,4R)-tert-butyl 4-hydroxy-2-(thiazolidine-3- carbonyl)pyrrolidine-1-carboxylate by treating (2S,4S)-tert-butyl 4-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-2-(3-thiazolidinylcarbonyl)pyrrolidine-1- carboxylate with tetrabutylammonium fluoride in tetrahydrofuran.

Bioorganic & Medicinal Chemistry, 20(19), 5705-5719 (2012) discloses the 5 process for the preparation of herein compound (II) after by reacting 1-(3-methyl- 1-phenyl-1H-pyrazol-5-yl)piperazine herein compound (V) with (2S,4R)-tert-butyl 4-hydroxy-2-(thiazolidine-3-carbonyl)pyrrolidine-1-carboxylate in presence of sodium triacetoxyborohydride. There is provided different alternative processes for the preparation of teneligliptin and intermediates thereof.

Bioorganic & Medicinal Chemistry, 20(19), 5705-5719 (2012) also discloses the process for the preparation of 4-[4-(5-methyl-2-phenyl-2H-pyrazol-3-yl)-piperazin- 1-yl]-2-(thiazolidine-3-carbonyl)pyrrolidine-1-carboxylic acid tert-butyl ester [herein compound (II)] after by reacting 1-(3-methyl-1-phenyl-1H-pyrazol-5- 15 yl)piperazine [herein compound (V)] with (2S,4S)-tert-butyl 4-[[(1,1- dimethylethyl)dimethylsilyl]oxy]-2-(3-thiazolidinylcarbonyl)pyrrolidine-1- carboxylate in presence of trifluoromethylsulfonic anhydride and diisopropylethylamine. 3 – [[(2S, 4S) -4- [4- (3- methyl-1-phenyl–1H- pyrazol-5-yl) -1-piperazinyl ] -2-pyrrolidinyl] carbamoyl] thiazolidine, having the formula below, is a very novel DPP-4 inhibitor potential.

World Patent Application No. W02012099915 for Ge Lieting discloses a process for the preparation route is as follows:

Journal B10rganic & Medicinal Chemistry, 2012, 20, 5705-5719 also discloses a preparation method for Ge Lieting, the route is as follows:

[0009] 1- (3-methyl-1-phenyl-5-pyrazolyl) piperazine, was prepared for the Ge Lieting key intermediate. Journals B10rganic & Medicinal Chemistry, 2012,20,5705-5719 reported the preparation of the intermediates prepared route is as follows:

[0011] The preparative route after the N-Boc-N- acetoacetyl piperazine phenylhydrazine and methanesulfonic acid in an ethanol solution of the reaction at room temperature 14h, concentrated under reduced pressure after addition of pyridine.Was added phosphorus oxychloride in pyridine, 20h post treatment reaction at room temperature the reaction system. The compound obtained above was then added trifluoroacetic acid was dissolved in methylene chloride after, after treatment at room temperature for 1.5h to give 1- (3-methyl-1-phenyl-5-pyrazolyl) piperazine.

The reaction process requires mesylate mesylate flammable, easy-absorbent deliquescence, and has a strong corrosive and irritating, easy to cause the body burns; phosphorus oxychloride, a highly toxic substance, water violent hair in the air smoke, hydrolyzed into phosphoric acid and hydrogen chloride, is very unstable, to operate a lot of trouble; trifluoroacetic acid is highly corrosive and irritant, can cause the body burns; low yield of the reaction (10%). Seeking a simple operation, high reaction yield, low cost and suitable for industrial production production process 1- (3-methyl-1-phenyl-5-pyrazolyl) piperazine has a very important role in the field of medicine.

…………………………………….

since the capture is staggered, compd 165 is not clear in above pic see below

…………

…………………….

CN104177295

reaction scheme in http://www.google.com/patents/CN104177295A?cl=en

Description: LR as Lawesson reagent (Lawesson Reagent), is a sulfur oxygen exchange reagent. The present invention provides a method for preparing key intermediates Ge Lieting method, comprising the steps of: (I) N-Boc-N- acetoacetyl piperazine Lawesson’s reagent in the presence of an organic solvent, with a phenylhydrazine of the formula occurs ⑴ reaction shown:

(2) the step (1) The product was dissolved in an organic solvent, the following formula (II) in concentrated hydrochloric acid to deprotected shown:

格列汀 refers to 1- (3-methyl-1-phenyl-5-pyrazolyl) piperazine

……………………………..

Bioorganic & Medicinal Chemistry

Volume 20, Issue 19, 1 October 2012, Pages 5705–5719

http://www.sciencedirect.com/science/article/pii/S0968089612006347

…………………………………..

………………………..

http://www.google.co.in/patents/WO2015019238A1?cl=en

Example 5: Preparation of {(2^^,.4^)-4-r4-(3-methyl-l-phenyl-lH-pyrazol-5-yl)piperazin- 1 -vHpyrrolidin-2-yl } ( 1.3 -thiazolidin-3 -vDmethanone hemipentahydrobromide hydrate (Formula II)

Activated carbon (10 g) was added to a solution of the residue (obtained in Example 4) in isopropyl alcohol (1000 mL) at 30°C to 35°C. The reaction mixture was filtered through a Hyflo^® bed. The filtrate was heated to a temperature of 70°C to 75°C. Hydrobromic acid (48%; 168 g) was slowly added to the filtrate at 70°C to 75°C over a period of 10 minutes to 15 minutes. The reaction mixture was stirred for 2.5 hours at 70°C to 77°C. The progress of the reaction was monitored by HPLC. After completion of the reaction, the reaction mixture was cooled to a temperature of 20°C to 25 °C, and stirred at the same temperature for 60 minutes. The reaction mixture was filtered to obtain a solid. The solid obtained was washed with isopropyl alcohol (2 x 200 mL), and dried at 50°C under reduced pressure for 15 hours to obtain crude {(25^*,45)-4-[4-(3-methyl-l-phenyl-lH- pyrazol-5 -yl)piperazin- 1 -yl]pyrrolidin-2-yl} ( 1 ,3 -thiazolidin-3 -yl)methanone

hemipentahydrobromide hydrate.

Yield: 90%

Example 6: Purification of {(2^’.4^)-4-r4-(3-methyl-l-phenyl-lH-pyrazol-5-yl)piperazin- 1 -yllpyrrolidin-2-yl } ( 1.3 -thiazolidin-3 -vDmethanone hemipentahydrobromide hydrate (Formula II)

A reaction mixture containing {(2S,4S)-4-[4-(3-methyl-l-phenyl-lH-pyrazol-5- yl)piperazin- 1 -yl]pyrrolidin-2-yl } ( 1 ,3 -thiazolidin-3 -yl)methanone

hemipentahydrobromide hydrate (100 g; prepared according to the process of Example 5) in ethanol (700 mL) was heated at 70°C to 75°C to obtain a solution. The solution was filtered at the same temperature. The filtrate was allowed to cool to a temperature of 65 °C to 68°C, and deionized water (10 mL) was added at the same temperature. The solution was cooled to a temperature of 55°C to 60°C, and stirred at the same temperature for 2 hours. The solution was further cooled to a temperature of 20°C to 25 °C, and stirred at the same temperature for 60 minutes to obtain a solid. The solid was filtered, washed with ethanol (100 mL), and dried at 45°C to 50°C under reduced pressure for 18 hours to 20 hours to obtain pure {(2S,4S)-4-[4-(3-methyl-l-phenyl-lH-pyrazol-5-yl)piperazin-l- yl]pyrrolidin-2-yl } ( 1 ,3 -thiazolidin-3 -yl)methanone hemipentahydrobromide hydrate .

Yield: 90%

HPLC Purity: 99.93%

WO2012099915A1 *	18 Jan 2012	26 Jul 2012	Hongwen Zhu	Thiazolidine derivatives and their therapeutic use
WO2012165547A1 *	31 May 2012	6 Dec 2012	Mitsubishi Tanabe Pharma Corporation	Method for manufacturing pyrazole derivative
WO2014041560A2 *	28 Aug 2013	20 Mar 2014	Glenmark Pharmaceuticals Limited; Glenmark Generics Limited	Process for the preparation of teneligliptin
US7074794	10 Aug 2001	11 Jul 2006	Mitsubishi Pharma Corporation	Proline derivatives and the use thereof as drugs
US8003790	17 Feb 2006	23 Aug 2011	Mitsubishi Tanabe Pharma Corporation	Salt of proline derivative, solvate thereof, and production method thereof
US20050256310 *	12 May 2005	17 Nov 2005	Pfizer Inc	Therapeutic compounds

EP1854795A1 *	17 Feb 2006	14 Nov 2007	Mitsubishi Pharma Corporation	Salt of proline derivative, solvate thereof, and production method thereof
EP1894567A1 *	2 Jun 2006	5 Mar 2008	Mitsubishi Tanabe Pharma Corporation	Concomitant pharmaceutical agents and use thereof
US20040106655 *	10 Aug 2001	3 Jun 2004	Hiroshi Kitajima	Proline derivatives and the use thereof as drugs

Patent	Filing date	Publication date	Applicant	Title
WO2015019238A1 *	28 Jul 2014	12 Feb 2015	Ranbaxy Laboratories Limited	Process for the preparation of n-protected (5s)-5-(1,3-thiazolidin-3-ylcarbonyl)pyrrolidin-3-one

Patent	Submitted	Granted
Proline derivatives and use thereof as drugs [US7060722]	2005-11-03	2006-06-13
Proline derivatives and the use thereof as drugs [US7074794]	2004-06-03	2006-07-11
Proline derivatives and use thereof as drugs [US2006173056]	2006-08-03
SALT OF PROLINE DERIVATIVE, SOLVATE THEREOF, AND PRODUCTION METHOD THEREOF [US8003790]	2009-08-27	2011-08-23
METHOD OF TREATING ABNORMAL LIPID METABOLISM [US2010305139]	2010-12-02
COMBINED USE OF DIPEPTIDYL PEPTIDASE 4 INHIBITOR AND SWEETENER [US2010113382]	2010-05-06
CONCOMITANT PHARMACEUTICAL AGENTS AND USE THEREOF [US2009082256]	2009-03-26
PROPHYLACTIC/THERAPEUTIC AGENT FOR ABNORMALITIES OF SUGAR/LIPID METABOLISM [US2009088442]	2009-04-02
SALT OF PROLINE DERIVATIVE, SOLVATE THEREOF, AND PRODUCTION METHOD THEREOF [US2011282058]	2011-11-17

Joanne Bronson, Amelia Black, T. G. Murali Dhar, Bruce A. Ellsworth, and J. Robert Merritt. “Teneligliptin (Antidiabetic)”. Annual Reports in Medicinal Chemistry 48: 523–524. doi:10.1016/b978-0-12-417150-3.00028-4.
Kishimoto, M (2013). “Teneligliptin: A DPP-4 inhibitor for the treatment of type 2 diabetes”. Diabetes, metabolic syndrome and obesity : targets and therapy 6: 187–95. doi:10.2147/DMSO.S35682. PMC 3650886. PMID 23671395.

see gliptins at………….http://drugsynthesisint.blogspot.in/p/gliptin-series.html

http://organicsynthesisinternational.blogspot.in/p/gliptin-series-22.html

see gliptins at………….http://drugsynthesisint.blogspot.in/p/gliptin-series.html

http://organicsynthesisinternational.blogspot.in/p/gliptin-series-22.html

trans-Cinnamamide , (2E)-3-Phenyl-2-propenamide

Uncategorized Comments Off

Jun 272015

trans-Cinnamamide/(2E)-3-Phenyl-2-propenamide

Name	trans-Cinnamamide
Synonyms	(2E)-3-Phenyl-2-propenamide
Name in Chemical Abstracts	2-Propenamide, 3-phenyl-, (2E)-
CAS No	22031-64-7
EINECS No
Molecular formula	C₉H₉NO
Molecular mass	147.18
SMILES code	NC(=O)/C=C/c1ccccc1

1H NMR

¹H-NMR: trans-Cinnamamide
250 MHz, DMSO-d₆
delta [ppm]	mult.	atoms	assignment
6.61	d (J_AB= 15.9)	1 H	C=CH-CO (2-H)
7.13	broad s	1 H	NH
7.2-7.6	m	7 H	CH (arom.) + NH + -CH=C (3-H)
7.42	d (J_AB= 15.9)	1 H	-CH=C (3-H)
6.53	d	1 H	C=CH-CO (2-H, cinnamic acid)
7.82	d	1 H	-CH=C (3-H, cinnamic acid)
2.5	s		DMSO
3.33	s		O-CH₃ (tBu-OMe)
1.19	s		C-CH₃ (tBu-OMe)

¹³C-NMR

13C NMR

¹³C-NMR: trans-Cinnamamide
250 MHz, DMSO-d₆
delta [ppm]	assignment
122.31	C2 (=CH-)
127.52	CH arom.
128.90	CH arom.
129.42	C4 (arom.)
134.86	C quart. arom.
139.16	C3 (-CH=C)
166.68	C1 (-C(=O)NH₂)
38.5-40.5	DMSO-d₆

IR

IR: trans-Cinnamamide
[KBr, T%, cm^-1]
[cm^-1]	assignment
3375, 3175	N-H valence
3084	aliph. C-H valence, =C-H
1665	C=O valence, carboxamide
1610	alkene C=C valence
1580, 1495	arom. C=C valence

Chromatogram

crude product chromatogram

HPLC: crude product
column	Phenomenex Luna C18; particle diameter 3 µm, L= 150 mm, ID= 4.6 mm
column temperature	25 °C
injection	5 µL
mobile phase	5% MeCN / H2O (0.0059% CF3COOH), gradient to 95% MeCN / H2O (40 min), 10 min isocratic
flow	1.0 mL/min
detector (UV 220 nm)	percent concentration calculated from relative peak area

pure product chromatogram

HPLC: pure product
column	Phenomenex Luna C18, particle diameter 3 µm, Länge 150 mm, Innendurchmesser 4.6 mm
column temperature	25 °C
injection	5 µL
mobile phase	5% MeCN/H2O (0.0059% CF3COOH), gradient to 95% MeCN/H2O (40 min), 10 min isocratic
flow	1.0 mL/min
detector (UV 220 nm)	percent concentration calculated from relative peak area



Name	trans-Cinnamamide
Synonyms	(2E)-3-Phenyl-2-propenamide
Name in Chemical Abstracts	2-Propenamide, 3-phenyl-, (2E)-
CAS No	22031-64-7
EINECS No
Molecular formula	C₉H₉NO
Molecular mass	147.18
SMILES code	NC(=O)/C=C/c1ccccc1

NH₃

IR

IR: trans-Cinnamamide
[KBr, T%, cm^-1]
[cm^-1]	assignment
3375, 3175	N-H valence
3084	aliph. C-H valence, =C-H
1665	C=O valence, carboxamide
1610	alkene C=C valence
1580, 1495	arom. C=C valence

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Denpasar, bali, indonesia

Denpasar – Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Denpasar

Denpasar (Indonesian: Kota Denpasar, Indonesian pronunciation: [dənˈpasar]) is the capital and the most populous city of the Indonesian province of Bali.

‎Etymology – ‎History – ‎Geography – ‎Demography

.

Jagatnatha Temple Denpasar | Bali Places to Visit

www.balisurfadvisor.com

Denpasar market, Denpasar is the capital of Bali Province. The main street of Denpasar is Gajah Mada street where is the main shopping center, .

A very giant Ogoh-ogoh at a cross junction in Denpasar

A view from the Kumbasari Market

PT (PERSERO) ANGKASA PURA I CABANG BANDARA NGURAH RAIGEDUNG WISTI SABHA LANTAI 3 BANDARA NGURAH RAIDENPASAR, BALI 80362

Bali Airport (Ngurah Rai) Denpasar – Indonesia

Bali Ngurah Rai International Airport, also known as Denpasar International Airport, is located in southern Bali, 13 km south of Denpasar. It is Indonesia’s third-busiest international airport.

Bajak Laut Nasi Tempong & Seafood, Renon, Bali

Sporting the growth of Denpasar residents’ likes for Nasi Tempong, Bajak Laut Nasi Tempong & Seafood sets on a different kind of path by combining Nasi Tempong with the other well-known Bali’s best: Seafood.

Sets in the cozy neighborhood of Renon, Denpasar, Bajak Laut is the newest addition of restaurant openings in this area. From the down-to-earth food courts selling Ayam Goreng, Chinese food and Sup Kepala Ikan, to the more luxurious XO Suki & Cuisine, Ayucious, or the more established Bendega, Ikan Bakar Cianjur, and Hanamasa, Bajak Laut further marks Renon as a leading Denpasar’s culinary destination.

Though opened really close to the market leader Nasi Tempong Indra, that with its aggressive market expansion in 2012 opens two new branches around Renon area alone, Bajak Laut however has what Indra has not: various choices of seafood comprising of fishes, shellfish, crabs, and shrimps. Therefore market wise, Bajak Laut is aiming at a slightly different crowds: those who loves the spicy Nasi Tempong, and those who loves Seafood; especially those too tired to go through all the traffic madness at Simpang Siur to reach Jimbaran.

(Or believes it’s too touristy.)

As the champion of this premise, Bajak Laut offers “Kepiting Asap ala Bajak Laut”, which are crabs cooked in sweet and savory rubs, then grilled inside banana leaf wraps to enhance its aroma. The result is a treat not only delicious to the taste but also to the sight.

Ingredients used for the rub is dominated with daun salam, or Indonesian bay leaves. For those familiar with gepuk; fried beef first marinated in spices and brown sugar, Kepiting Asap ala Bajak Laut has an almost identical seasoning.

One portion of Kepiting Asap ala Bajak Laut consisting of two crabs weighing total of 5 ons (500 grams). At 120K they’re good for two, while the 7 ons one costs 150K. For the 5 ons portion, the crab size is a bit small, hence eating them requires quite an effort.

Nasi Tempong is a good example how a food originated from outside Bali could becomes a local hit. Originated from Banyuwangi, Nasi Tempong managed to get quite followers due to its main character of super spicy sambal. Nasi Tempong usually served as a package consisting of white rice, steamed vegetables, tahu, tempe, anemic salted fish, and super spicy sambal, and a main dish of either fried chicken, or other kind of proteins.

While I’m not a die-hard spicy food fans, I found their Nasi Tempong quite palatable, especially since the stewed vegetables plus sambal that’s the core of every Nasi Tempong dish, is like a staple food in Western Java where I grew up.

Service is polite and attentive, though we found it’s a bit hard to get attention from the waiters, except from the one stand by the front door. Beside of the seafood, the Nasi Tempong variations are sold around 12K to 45K,

Starting December 2013 but don’t know for how long, Bajak Laut Nasi Tempong & Seafood offers a special discount for their set menu, at 150K for 4 people, and 250K for 6 people.

One annoying condition that we have to face as well, that even though the premise is fully airconed, people are allowed to smoke! And here in Denpasar, Bali, sadly it’s the common case with many eating premises, and Bajak Laut is no exception. Therefore while their crab is quite delicious, until Bajak Laut separates its smoking and non-smoking section it poses health hazard to your youngsters. (byms)

Bajak Laut Nasi Tempong & Seafood
Jl. Cok Agung Tresna No.23, Renon, Denpasar, Bali
(0361) 7984007

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11-Chloro-1-undecene

Uncategorized Comments Off

Jun 272015

11-Chloro-1-undecene



Name	11-Chloro-1-undecene
Synonyms
Name in Chemical Abstracts	1-Undecene, 11-chloro-
CAS No	872-17-3
EINECS No
Molecular formula	C₁₁H₂₁Cl
Molecular mass	188.74
SMILES code	ClCCCCCCCCCC=C

SOCl₂

¹H-NMR

1H NMR

¹H-NMR: crude product
300 MHz, CDCl₃
delta [ppm]	mult.	atoms	assignment
1.1-1.5	m	12 H	CH₂
1.75	tt	2 H	2-H
2.02	dt	2 H	9-H
3.51	t	2 H	1-H
4.95	2xdd	2 H	11-H
5.80	m	1 H	10-H

1H NMR

¹H-NMR: 11-Chloro-1-undecene
300 MHz, CDCl₃
delta [ppm]	mult.	atoms	assignment
1.1-1.5	m	12 H	CH₂
1.75	tt	2 H	2-H
2.02	dt	2 H	9-H
3.51	t	2 H	1-H
4.95	2xdd	2 H	11-H
5.80	m	1 H	10-H

¹³C-NMR

13C NMR

¹³C-NMR: crude product
75.5 MHz, CDCl₃
delta [ppm]	assignment
32.7	C2
33.9	C9
45.0	C1
114.1	C11
139.1	C10
76.5-77.5	CDCl₃

13C NMR

¹³C-NMR: 11-Chloro-1-undecene
75.5 MHz, CDCl₃
delta [ppm]	assignment
32.7	C2
33.9	C9
45.0	C1
114.1	C11
139.1	C10
76.5-77.5	CDCl₃

IR

IR: 11-Chloro-1-undecene
[Film, T%, cm^-1]
[cm^-1]	assignment
3077	aliph. C-H valence, H₂C=C
2927, 2855	aliph. C-H valence
993, 910	deform. C-H, H₂C=C
723	C-Cl valence

Operating scheme

Chromatogram

crude product chromatogram

GC: crude product
column	DB-WAX, L=30 m, d=0.33 mm, film=0.25 µm
inlet	on column injection, 0.2 µL
carrier gas	H2, 40 cm/s
oven	90°C (5 min), 10°C/min –> 240°C (30 min)
detector	FID, 270°C
integration	percent concentration calculated from relative peak area

pure product chromatogram

GC: pure product
column	DB-WAX, L=30 m, d=0.33 mm, film=0.25 µm
inlet	on column injection, 0.2 µL
carrier gas	H2, 40 cm/s
oven	90°C (5 min), 10°C/min –> 240°C (30 min)
detector	FID, 270°C
integration	percent concentration calculated from relative peak area

8 must-see places in Southeast Asia for great views: bucket list 2015

Southeast Asia is more than food and culture; here are 8 eye-candy places with magnificent views for a highly memorable trip!

Not just a melting pot of cultures, religions, history and food, Southeast Asia offers many picturesque spots that your eyes will thank you for. Whether it’s enjoying a sunset from a mountain top or just taking in the bucolic sights of Mother Nature’s hand-sculpted terrains, you’ll attest that these 8 suggestions offer some pretty unique charms that take your breath away.

1. Inle Lake, Myanmar

Myanmar has become a hotspot for the intrepid traveller and opens up plenty of opportunities to lap up many of its natural scenic wonders. If you’re heading there, a must-see place is Inle Lake renowned for its vast body of water where one can spot fishing communities and homes built on stilts.

Not only is the lake famous for its photogenic quality, you can hire guides to visit fish farms and shop at handicraft stores. Inle Lake’s picturesque charm comes from watching leg-rowing fisherman haul their catch during sunset. Find cheap flights to the capital Naypyidaw and best time to travel there is between November and February.

Be mesmerised by the scenic Inle Lake in Myanmar

2. Tiger’s Nest Monastery, Bhutan

Perched some 3,000 metres above sea level and build in 1692, Bhutan’s Taktsang monastery, or more popularly known as Tiger’s Nest, is a must-see when you come to this nation steeped in Buddhist history. Getting there is not for the faint-hearted as one has to traipse through a hilly, rocky and undulating path to reach the peak.

Do hire guides to reach the apex successfully, and you’ll be rewarded by 360-views of sylvan mountain tops. Spring time from March to May is the best time to visit Bhutan and Drukair Royal Airlines of Bhutan flies theredirect.

Take in the lofty, airy views of Tiger’s Nest in Bhutan

3. Mount Kinabalu, Sabah, Malaysia

Recognised as one of the tallest peaks in Southeast Asia, Mount Kinabalu is a trekker’s dream come true. Getting to the summit takes about two days to accomplish. There is a 4-km climb to Laban Rata lodge where you can rest and replenish on sustenance. The next day is a 2-km climb to Low’s Peak.

The trek may be arduous but with lush rainforest terrain, there’s always something new at every corner to keep you distracted. About a kilometer away from the peak, the terrain changes to rock, stone and pebbles complemented by vegetation normally found in cooler climes. To catch the sunrise on the second day, it’s advisable to depart at 2am but remember to bring extra clothing as the mercury will drop to 2 degrees Celsius.

The scenic misty peaks of Mt. Kinabalu also offer spots for picturesque photos

4. Palawan Island, Luzon, Philippines

Recently coined by Huffington Post as “The Most Beautiful Island In the World” while Conde Nast Traveler’sReader Choice Awards named it “The Top Island in the World”, Palawan island is quite the magnificent sight. With its beautiful azure waters infused with emerald hues, it’s also hard to refute such claims.

Dotting the waters are jungled-filled islands, each with a distinctive hill rising above the ocean. Just by half-hour domestic flight from Manila airport, once you soar above Palawan’s oceanic landscape, you’ll feel like you’ve reached Shangri-la. Whether it’s island-hopping or sea kayaking, fun-filled times are never in short supply.

The beaches of Palawan have powdery white sand!

5. Penang National Park, Malaysia

Penang is truly a foodie paradise but many people are flocking there for other reasons, one being its attractive natural environment. Located just west of mainland Malaysia, a flight from Singapore is slightly over an hour.

With plenty of diverse lifestyle choices and entertainment options, Penang also has its idyllic charms. Aside from its UNESCO-designated George Town, the Penang National Park located on the North-Western side of the island rewards one with rich rainforests, a diverse ecosystem and some 1,381 hectares of wetlands to indulge trekking fanatics and eco-photographers.

6. Tanah Lot Temple, Bali, Indonesia

Bali is never in short supply of mysticism and wonder. A two-hour flight out of Singapore is all it takes to enjoy a short vacation. And of course, visiting its picturesque sea temple on the west coast of Bali, Tanah Lot, promises many Kodak moments. A simple traipse during low-tide rewards a sight to behold too – a Hindu shrine ensconced among lush trees perched on a rock is postcard-worthy from any angle. Framed by crashing waves, Tanah Lot Temple brims with a dab of fable and mysticism that makes it a must-see when visiting Bali!

Tanah Lot in Bali offers scenic views of splendid structures amidst crashing waves

7. Angkor Wat, Siem Reap, Cambodia

Angkor Wat became even more famous, thanks to the Tomb Raider movie starring Angelina Jolie. Founded in the 12th Century, it is also the 7th Wonder of the World. This Khmer temple’s architecture will seize the gaze of any first-time visitor. At the centre of this city, within a moat, is a towering stupa that provides sylvan views of its 3.6km, vine-covered outer wall. Just 5.5km north of Siem Reap, the Angkor Archaeological Park is a must-see for travellers with a penchant for history and artefacts.

Angkor Wat’s lush views are both captivating and mysterious

8. Halong Bay, Hanoi, Vietnam

Halong Bay, which means “Bay of Descending Dragons”, is a unique karst topography carved out by Mother Nature. The UNESCO World Heritage site offers views of vertical formations which are rich in dense vegetation. A boat cruise meandering through any of the 1,969 islets is both tranquil and insightful. Avoid the monsoons from June to September and from January to March, but visit the high seasons to enjoy sunny skies that won’t put a damper on your exploration plans of the natural outlying islets. After a three-hour fight to Hanoi from Singapore, take a five-hour road trip via mini bus to the port; it costs around USD 6 (SGD 7.50) and can be arranged upon arrival.