Oxyazapeptides: synthesis, structure determination, and conformational analysis.

Herein we report the synthesis, X-ray structure determination, and conformational analysis of a novel class of heteroatom-modified peptidomimetics, which we shall call "oxyazapeptides". Substituting the typical native N-C(α) bond with an O-N(α) bond creates a completely new, previously unknown family of peptidomimetics, which are hydrolytically stable and display very interesting conformational behavior. Force field calculations revealed that the barrier to rotation around the O-N(α) bond in oxyazapeptides is five times lower than that around the N-N(α) bond in azapeptides.