An approach to enantiomerically pure inverse gamma-turn mimetics for use in solid-phase synthesis

An inverse gamma-turn mimetic, having a morpholin 3-one ring as the key structural unit, was prepared in enantiomerically pure form in seven steps and 37% overall yield starting from 2(R)-[1'(S)-azido-2'-phenylethyl]oxirane (3). The mimetic has side-chains corresponding to a Phe-Ala-Ala tripeptide but the synthetic route was designed to allow incorporation also of other side chains. Molecular mechanics calculations revealed that the torsional angles of the second residue of the mimetic were effectively locked into an inverse gamma-turn like conformation. (C) 1997 Elsevier Science Ltd.