DIASTEREOSELECTIVE EPOXIDATION OF DIPEPTIDE OLEFINS

m-Chloroperbenzoic acid (MCPBA) epoxidation of dipeptide olefins proceeds in high syn diastereoselectivity (38:1-300:1). This is partially caused by conformational constraints introduced by the side chain that orients the allylic NH in a favorable position for hydrogen bonding to MCPBA. The possibility of an additional hydrogen bond between the N-terminal NH and MCPBA is excluded.