Preparation of (3S,4S)-(N-alpha-boc)-4-amino-5-cyclohexyl-3-hydroxypentanoic-acid ethyl ester.

摘要

Process comprising coupling of an acylimidazole-activated derivative of a reduced and protected phenylalanine with the magnesium salt of malonic acid monoethyl ester to produce the beta-ketoester, which is subsequently reduced with NaCNBH3/THF in glacial acetic acid to afford a separable mixture of 3-S and 3-R 3-hydroxy-(4S)-4-(N- alpha -BOC)amino-5-cyclohexylpentanoic acid, such that large-scale, high yield production of optically-active ACHPA is significantly improved.