May 172016

2D chemical structure of 1255204-84-2


cas  1255204-84-2

1(3H)-Isobenzofuranone, 5,5′-(1,4-piperazinediylbis((1R)-1-hydroxy-2,1-ethanediyl))bis(4-methyl-

MF C26 H30 N2 O6, Molecular Weight 466.53
1(3H)​-​Isobenzofuranone, 5,​5′-​[1,​4-​piperazinediylbis[(1​R)​-​1-​hydroxy-​2,​1-​ethanediyl]​]​bis[4-​methyl-

The Renal Outer Medullary Potassium (ROMK) channel (KM .1 ) (see e.g., Ho,K., et al., Cloning and expression of an inwardly rectifying ATP -regulated potassium channel, Nature, 1993, 362(6415): p. 31-8.1, 2; and Shuck, M.E., et al., Cloning and characterization of multiple forms of the human kidney ROM-K potassium channel, J Biol Chem, 1994, 269(39): p. 24261-70) is a member of the inward rectifier family of potassium channels expressed in two regions of the kidney: thick ascending loop of Henle (TALH) and cortical collecting duct (CCD) (see Hebert, S. C, et al., Molecular diversity and regulation of renal potassium channels, Physiol Rev, 2005, 85(1): p. 319-713). At the TALH, ROMK participates in potassium recycling across the luminal membrane which is critical for the function of the Na+/K+/2CF co-transporter, the rate-determining step for salt reuptake in this part of the nephron. At the CCD, ROMK provides a pathway for potassium secretion that is tightly coupled to sodium uptake through the amiloride-sensitive sodium channel (see Reinalter, S. C, et al., Pharmacotyping of hypokalemic salt-losing tubular disorders, Acta. Physiol Scand, 2004, 181(4): p. 513-21 ; and Wang, W., Renal potassium channels: recent developments, Curr Opin Nephrol Hypertens, 2004, 13(5): p. 549-55). Selective inhibitors of the ROMK channel (also referred to herein as inhibitors of ROMK or ROMK inhibitors) are predicted to represent novel diuretics for the treatment of hypertension and other conditions where treatment with a diuretic would be beneficial with potentially reduced liabilities (i.e., hypo- or hyperkalemia, new onset of diabetes, dyslipidemia) over the currently used clinical agents (see Lifton, R.P., A.G. Gharavi, and D.S. Geller, Molecular mechanisms of human hypertension, Cell, 2001, 104(4): p. 545-56). Human genetics (Ji, W., et al., Rare independent mutations in renal salt handling genes contribute to blood pressure variation, Nat Genet, 2008, 40(5): p. 592-9; and Tobin, M.D., et al., Common variants in genes underlying monogenic hypertension and hypotension and blood pressure in the general population, Hypertension, 2008, 51(6): p. 1658-64) and genetic ablation of ROMK in rodents (see Lorenz, J.N., et al., Impaired renal NaCl absorption in mice lacking the ROMK potassium channel, a model for type II Bartter’s syndrome, J Biol Chem, 2002, 277(40): p. 37871-80 and Lu, M., et al.s Absence of small conductance K+ channel (SK) activity in apical membranes of thick ascending limb and cortical collecting duct in ROMK (Banter’s) knockout mice, J Biol Chem, 2002, 277(40): p. 37881-7) support these expectations. To our knowledge, the first small molecule selective inhibitors of ROMK were reported from work done at Vanderbilt University as described in Lewis, L.M., et al., High-Throughput Screening Reveals a Small-Molecule Inhibitor of the Renal Outer Medullary Potassium Channel and KirJ.l, MoI Pharmacol, 2009, 76(5): p. 1094-1103.


WO 2010129379















14 15

The preparation of compounds 16 can be achieved following the sequence detailed in Scheme 9. Treating epoxide 2-1 with commercially available 1-Boc piperazine at elevated temperatures gives rise to alcohol 2-2 (Nomura, Y. et al. Chemical & Pharmaceutical Bulletin, 1995, 43(2), 241-6). The hydroxyl group of 2-2 can be converted to the fluoride by treatment of such fluorinating reagent as DAST (Hudlicky, M. Organic Reactions, 1988, 35). Removal of the Boc group of 3-1 under acidic conditions such as TFA gives rise to piperazine 3-2. Piperazine 3-2 can be washed with an aqueous base solution followed by extraction with organic solvents to generate the free base form. The free base of 3-2 can be coupled to epoxide 5-1 at elevated temperatures to afford compound 16. The Ar-CHF- and Ar’-CHOH- groups in 16 represent examples of either Z1 or Z2.


16 General Procedures.

INTERMEDIATE (Ry-H (free base)

5-\(lR)-l -hγdroxγ-2-piperazio- 1 -ylethyl] -4-methyl-2-benzofuran- 1 f 3/f)-one To a 20 mL microwave tube charged with 4-methyl-5-[(2jS)-oxiran-2-yl]-2-benzofuran-l(3H)-one (1020 mg, 5.40 mmol) and a stir bar was added 1-Boc Piperazine (800mg, 4.3 mmol) and EtOH (15 mL). The tube was sealed and heated in a microwave apparatus to 150 0C for 1 hour. The crude product was adsorbed onto silica gel, and purified by flash chromatography (Hexanes-EtOAc with 10% EtOH: 0 – 100% gradient), and solvent removed to afford terl-butyl~4-[(2R-2-hydroxy-2-(4-methyl-l -oxo-1 ,3-dihydro-2-bers2θfuran-5-yl) ethyl}piperazine-l-carboxylate. LCMS M+l (calc. 377.20, found 377.13). This product was treated with neat TFA for 15 minutes to remove the Boc group. After removal of TFA under reduced pressure, the residue was taken into aq NaHCO3, and back-extracted with CHCl3-IPA (3:1). The organic layers were combined, dried over sodium sulfate, and concentrated to afford 5 – [( 1 R)- 1 -hydroxy-2-piperazin- 1 -ylethyl] -4-methyl-2-benzofuran- 1 (3H)-one. 1H NMR (OMSO-d6, 500 MHz) δ 7.68 (d, J= 8.0 Hz, IH), 7.65 (d, J= 8.0 Hz, IH)5 5.38, 5.35 (AB system, J- 15.4, J= 16.7, 2H), 5.06 (dd5 J- 3.9 Hz, J= 3.7 Hz, IH), 3.76 (m, IH)5 2.72 (m, 4H), 2.42 (m, 4H), 2.34 (d, J= 3.8 Hz5 IH), 2.32 (d, J= 3.8 Hz, IH), 2.24 (s, 3H); LC/MS: (IE, m/z) [M +I]+ = 277.03.


5, 5 ‘-{ piperazine- 1 ,4-diylbis[( 1 R)- 1 -hydroxy ethane-2 , 1 -diyl] } bis(4-methyl-2-benzofuran- 1 (3H)-one)

Method 1: To a 20 mL microwave tube charged with 4-methyl-5-[(2i?)-oxiran-2-yl]-2-benzofuran-l(3H)-one (972 mg, 5.11 mmol) and piperazine (200 mg, 2.3 mmol) was added a stir bar and EtOH (16 mL). The tube was sealed and heated in a microwave apparatus to 150 0C for 90 minutes. The crude product was adsorbed onto silica gel, and purified by flash chromatography (MeOΗ-DCM 0 ~ 7% gradient). After removal of solvents, 5»5′-{piperazine-1 ,4-diyIbi s [( 1 R)- 1 -hydroxyethane-2, 1 -diyl] } bis(4-methyl-2-benzofuran- 1 (3 H)-one) was collected. 1H-NMR (500 MHz9 CDCl3) δ ppm 7.80 (s, 4H), 5.25 (s, 4H), 5.11 (d, J= 10.5 Hz5 2H), 4.00 (broad, 2H), 2.90 (broad, 4H)3 2.69-2.50 (m, 6H), 2.44 (t, J= 11 Hz, 2H), 2.29 (s, 6H); LCMS M+l (calc. 467, found 467).

Method 2: Piperazine (4.51 g, 52.4 mmol) and 4-methyl-5-[(2Λ)-oxiran-2-yl]-2-benzofuran-1 (3//)-one (20.0 g, 105 mmol) were charged to a 3-neck 500-mL roundbottom flask, equipped with a reflux condensor, under nitrogen. Toluene (80.0 mL, 751 mmol) and N,N-dimethylacetamide (80 mL, 854 mmol) were added to provide a suspension. The reaction mixture was warmed to 110 0C, becoming homogeneous at 25 0C. After stirring for 4.5 h at 110 0C, the temperature was increased to 115 °C to drive the reaction forward. After stirring for 48 h, the reaction mixture was cooled to RT. On cooling, crystallization occurred. Water was added via addition funnel (45 mL), generating a thick slurry. The suspension was filtered and the solids were washed with 4:1 water :DMA (60 mL), followed by water (2 x 35 mL). The solid was dried on the funnel under vacuum with a nitrogen sweep to constant mass. 5,5′-{Piperazine-l,4-diylbis[(li?)-l-hydroxyethane-2,l-diyl]}bis(4-methyl-2-beiizofurari-l(3H)-one) was isolated. 1H-NMR (500 MHz, CDCl3) δ ppm 7.80 (s, 4H), 5.25 (s, 4H), 5.11 (d, J- 11 Hz, 2H), 4.30-3.51 (broad, 2H), 2.90 (broad, 4H), 2.69-2.50 (m, 6H), 2.44 (t, J- 11 Hz, 2H), 2.30 (s, 6H).

Compounds of the present invention are amines and can therefore be converted to a variety of salts by treatment with any of a number of acids. For example, the compound of Example 2A can be converted to several different salt forms as shown in the following representative examples. These are selected examples and are not meant to be an exhaustive list; numerous additional salts can be prepared in a similar fashion using a variety of acids. EXAMPLE 2A-1 (di-HCl salt): 5,5t-{piperazme-l,4-diylbis[(17?)-l-hydroxyethane-2,l- diyl] } bis(4-methyl-2-benzofuran- 1 (3H)-one) dihydrochloride To a 250 mL pear shape flask charged with the free base (1.2 g, 2.6 mmol) and a stir bar was added DCM. The solution was stirred until all solids were gone. To this solution was added 4N HCl in dioxane (2.6 mL, 4.0 eq), and the mixture was allowed to stir for another 15 minutes. The solvent was removed on a rotary evaporator, and the product was left dry on a high vacuum pump until there was no weight change. The product was determined to be 5, 5 ‘-{piperazine- 1,4-diylbis [( 1 R)- 1 ~hydroxyethane-2, 1 -diyl] } bis(4-methyl-2-benzofuran- 1 (3i?)-one) dihydrochloride. EXAMPLE 2A-2 (HCl salt): 5,5’-{piperazine-l,4-diylbis[(l^)-l-hydroxyethane-2,l- diyl] } bis(4-methyl-2-benzofuran- 1 QHVone) hvdrochl oride

To a 20 dram vial charged with the free base (160 mg, 0.34 mmol) and a stir bar was added 0.1 M HCl in IPA. The solution was allowed to stir at RT for 30 minutes, and then heated to 400C for 1 hour. The solvent was removed under vacuum, and the resulting product was left on a high vacuum pump for 16 hours. The product corresponded to 5,5′-{piperazine-l,4-diylbis[(li?)-l-hydroxyethane~2, 1 -diyl] } bis(4-methyl-2-benzofuran- 1 (3 H)-one) hydrochloride.

EXAMPLE 2A-3 (mono-hydrate of the di-HCl salt): 5, 5′- {piperazine- l,4-diylbis[( Ii?)- 1-hydroxyethane-2,l-diyl] Ibis^-niethyl-g-benzofuran-lfS/^-one) dihydrochloride hydrate To a flask charged with the free base (1.0 g, 2.1 rnmol) and a stir bar was added 1 N HCl (50 mL). The mixture was allowed to stir until all solids dissolved. The solvent was removed on a rotary evaporator, and the resulting product was left on a high vacuum pump for 16 hours. The product was determined to be 5,5′-{piperazine-l ,4-diylbis[(li?)-l-hydroxyethane-2,l-diyl]}bis(4-methyl-2-benzofuran-l(3H)-one) dihydrochloride hydrate.

EXAMPLE 2A-4 (H2SO4 salt): 5.5′-{piperaziiie-l>4-diylbis[(lJΪ)-l-hydioxyethane-2,l- diyl] }bis(4-methyl-2-benzofuran-l(3/f)-one) sulfate (salt) To a 100 mL flask charged with a solution of the free base (154 mg, 0.330 mmol) in DMF : MeOH (3 : 1) (20 mL) and a stir bar was added 0.1 M H2SO4 (3.3 mL). The solution was allowed to stir at RT for 30 minutes, and then heated to 40 0C for 2 hours. A lot of solids formed during that time. The solvent was removed under vacuum, and the white solids were left on high vacuum for 16 hours to afford 5)5l-{piperazine-l,4-diylbis[(lJ?)~l-hydroxyethane-2,l-diyl] }bis(4-methyl-2-benzofuran-l(3H)-one) sulfate (salt).


Abstract Image

ROMK, the renal outer medullary potassium channel, is involved in potassium recycling at the thick ascending loop of Henle and potassium secretion at the cortical collecting duct in the kidney nephron. Because of this dual site of action, selective inhibitors of ROMK are expected to represent a new class of diuretics/natriuretics with superior efficacy and reduced urinary loss of potassium compared to standard-of-care loop and thiazide diuretics. Following our earlier work, this communication will detail subsequent medicinal chemistry endeavors to further improve lead selectivity against the hERG channel and preclinical pharmacokinetic properties. Pharmacological assessment of highlighted inhibitors will be described, including pharmacodynamic studies in both an acute rat diuresis/natriuresis model and a subchronic blood pressure model in spontaneous hypertensive rats. These proof-of-biology studies established for the first time that the human and rodent genetics accurately predict the in vivo pharmacology of ROMK inhibitors and supported identification of the first small molecule ROMK inhibitor clinical candidate, MK-7145.

Discovery of MK-7145, an Oral Small Molecule ROMK Inhibitor for the Treatment of Hypertension and Heart Failure

Departments of Discovery Chemistry, Ion Channels, §In Vivo Pharmacology, Cardiorenal, and Pharmacokinetics, Pharmacodynamics and Drug Metabolism, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
ACS Med. Chem. Lett., Article ASAP
DOI: 10.1021/acsmedchemlett.6b00122
*Tel: 908-740 4932. E-mail:




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