Stereoselective synthesis of vinylogous peptides

A trans or cis ethenyl group has been inserted between the α-carbon and the carboxyl group of α-aminoacids by Horner stereoselective olefination of α-aminoaldehydes. Numerous pure cis and trans vinylogous α-aminoacids have been obtained thus and coupled with aminopartners by classical methods. The versatility of the method was illustrated by the preparation of a [trans vinylogous-Gly3]Leu-enkephalin.