Epoxidation of peptidyl olefin isosteres. Stereochemical induction effect of chiral centers at four adjacent C-alpha positions

Four tripeptidyl olefin isosteres were prepared, each of which contains a s ingle chiral center derived from the bulky amino acid phenylalanine at posi tions corresponding to the P-2-P'(2) positions of a protease substrate. The effect of these chiral centers on the stereochemical outcome of mCPBA epox idation of the olefin functionality was studied. A chiral center at P-2 or P'(2) position has no significant effect, and the P'(1) position exerts a s mall stereoselectivity. A chiral center at the P-1 position, on the other h and, has a profound chiral induction effect on the epoxidation reaction. (C ) 2000 Elsevier Science Ltd. All rights reserved.