Process for producing norstatin derivatives

摘要

This invention to provide a process for producing an optically active threo-phenylnorstatin derivative which does not require a toxic cyanating agent or a costly reagent, or a complicated procedure, and can be practiced on a commercial scale. This invention is directed to a process for producing a beta -amino- alpha -hydroxy acid derivative which comprises treating either a gamma -amino- beta -keto sulfoxide derivative with a halogenating agent to produce a gamma -amino- alpha -halo- beta -keto sulfoxide derivative, treating the same with an acid and an alcohol to produce a beta -amino- alpha -keto ester derivative or beta -amino- alpha -keto acid derivative, and followed by reducing.