STEREOSELECTIVE SN2' ADDITIONS OF ORGANOCUPRATES TO HOMOCHIRAL ACYLIC VINYLOXIRANES

Article abstract of DOI:10.1016/0040-4020(89)80067-5

Additions of various methylcopper reagents to the homochiral acylic vinyloxiranes A14, A15, B6-B9, and C5, C6 were performed in order to evaluate E/Z and syn/anti preferences.The unsubstituted oxiranes A14 and A15 gave a mixture of S_N2 and S_N2' substitution products with the four reagents examined, LiMe2Cu, LiMeCuCN, BrMgMe2Cu, and LiMeCuI*BF3.The more highly substituted systems B6-B9 derived from geraniol and C5, C6 derived from nerol yielded only S_N2' products.The (Z)-allylic alcohol derivatives B8 and C6 and LiMeCuCN gave the best anti/syn ratios (99:1 and 97:3, respectively).In both cases the newly formed double bond was exclusively E.