A new synthesis of ampicillin and related investigations

Abstract

Quaternization of (S)‐α‐bromophenylacetic acid amide (8) with hexamethylentetramine (hexamine) preceded with ca. 80% inversion of configuration. Accordingly, starting from the trimethylsilylester of N‐(S)‐(α‐bromo‐α‐phenylacetyl)‐6‐aminopenicillanic acid (4) quaternization with hexamine and subsequent hydrolysis afforded N‐(R)‐α‐phenylglycyl‐6‐aminopenicillanic acid (1, ampicillin). Some other model reactions have been investigated.