The first systematic study of the cis and trans stereoselectivity in the m-CPBA epoxidation of N-protected cyclic allylic amines has been completed. Mono-N-protected systems gave epoxides with cis stereochemistry (amides are better cis directors than sulfonamides or carbamates) whereas di-N-protected systems gave trans-epoxides (TsNBoc protection gave complete trans stereoselectivity). [structure: see text]

Epoxidation O 0218 cis-and trans-Stereoselective Epoxidation of N-Protected 2-Cyclohexen-1-ylamines. -Complementary routes to cis-and trans-epoxides from protected cyclic allylic amines are established. With mono-N-protected alkenes, it is demonstrated that amides are better cis-directors of epoxidation than sulfonamides or carbamates (>95:5 cis/trans). The presence of an N-Boc substituent is crucial for high stereoselectivity (>98:2 trans/cis) in the epoxidation of di-N-protected alkenes. Rearrangement of epoxides in situ or after treatment with acid generates oxazolidinones [cf. (VIII)], which appear to be very useful, stereodefined synthetic building blocks. -(O'BRIEN*, P.; CHILDS, A. C.; ENSOR, G. J.; HILL, C. L.; KIRBY, J. P.; DEARDEN, M. J.; OXENFORD, S. J.; ROSSER, C. M.; Org. Lett. 5 (2003) 26, 4955-4957; Dep. Chem., Univ. York, Heslington, York YO10 5DD, UK; Eng.) -Steudel 18-041