Synthesis, Enzymic Degradation, Lipophilic Properties, and Biological Activity of [<scp>D</scp>‐Alanine², <i>t</i>‐butylglycine⁵]enkephalin Amide

Abstract

Abstract L ‐ C α ‐ t ‐Butylglycine (Bug), its amide, methyl ester, and N α ‐ t ‐butoxycarbonyl derivative were prepared by an asymmetric synthesis, and the Hansch side‐chain hydrophobic (lipophilicity) parameter determined. A new enkephalin analogue, H · Tyr‐ D ‐Ala‐Gly‐Phe‐Bug · NH 2 was synthesized which is pharmacologically active in two in vitro assays and strongly resistant against a number of enzymes in vitro .