Cyclization reactions of beta,beta-difluoroalkyl radicals were carried out. 5 or 6-Exo selective radical cyclizations gave gem-difluorocyclopentane or -cyclohexane derivatives in 53 - 96% yields. 2,5-Disubstituted-3,3-difluorotetrahydropyran derivatives were prepared in 36 - 82% yields with moderate trans-selectivity (2.0 : 1-3.1 : 1). 4,5-Disubstituted-3,3-difluorotetrahydopyran derivatives were obtained via radical deoxygenation in 60 - 74% yields. High stereo-selectivity of radical cyclization for the formation of gem-fluorotetrahydropyran rings was achieved by introducing the bulky TBDPS group onto the acceptor double bond.
LINDERMAN, RUSSELL J.;GRAVES, DAVID M., J. ORG. CHEM., 54,(1989) N, C. 661-668
作者:LINDERMAN, RUSSELL J.、GRAVES, DAVID M.
DOI:——
日期:——
LANG, ROBERT W.;SCHAUB, BRUNO, TETRAHEDRON LETT., 29,(1988) N 24, C. 2943-2946