The synthesis of monocyclic, spirocyclic and fused bicyclic secondary amines bearing a gem-difluorocyclopropane moiety via difluorocyclopropanation of unsaturated N-Boc derivatives using the trifluoromethyl(trimethyl)silane/sodium iodide [CF3SiMe3-NaI] system is described. The relative order of the substrate reactivity is established. It is shown that for the reactive alkenes the standard reaction conditions can be used, whereas for the substrates with low reactivity, slow addition of the Ruppert–Prakash reagent is necessary.
Dmitriy M. Volochnyuk
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Murmanska Street 5, Kyiv 02660, Ukraine
Dmitriy M. Volochnyuk was born in 1980 in Irpen, Kyiv region, Ukraine. He graduated from Kyiv State Taras Shevchenko University in 2002 and was awarded his M.S. degree in chemistry. He received his Ph.D. in organic chemistry in 2005 from the Institute of Organic Chemistry, National Academy of Sciences of Ukraine under the supervision of Dr. A. Kostyuk for research on the chemistry of enamines. At present, he divides his time between the Institute of Organic Chemisty, as Deputy Head of Organophosphorus Department and Senior Researcher, and Enamine Ltd (Kyiv, Ukraine), as Director of Chemistry. His main scientific interests are related to fluoroorganic, organophosphorus, heterocyclic and combinatorial chemistry, and multistep organic synthesis. He is a coauthor of more than 80 papers
tert-Butyl 1,1-difluoro-6-azaspiro[2.5]octane-6-carboxylate (10a):
Yield: 66.7 g (91%) (Method A); off-white crystalline powder: mp 46–48 8C;
1H NMR (CDCl3 , 400 MHz): d= 3.57–3.42 (m, 2H), 3.40–3.27 (m, 2H), 1.66–1.47 (m, 4H), 1.44 (s, J=2.3 Hz, 9H), 1.08 (t, J=8.3 Hz, 2H);
13C NMR (CDCl3, 101 MHz): d=154.2, 115.4 (t, J=288.1 Hz), 79.3, 42.8, 28.4, 28.1, 26.8 (t, J=10.0 Hz), 21.0 (t, J=10.1 Hz);
19F NMR (CDCl3 , 376 MHz): email@example.com;
MS (EI): m/z= 247 (M+ ), 192 (M+@t-Bu), 174 (M+@t-BuO), 147 (M+@Boc), 127 (M+@Boc@HF);
Anal. calcd. for C12H19F2NO2 : C 58.29, H 7.74, N 5.66; found: C 58.49, H 8.02, N 5.30.