Synthesis of enantiopure non‐natural α‐amino acids usingtert‐butyl (2S)‐2‐[bis‐(tert‐butoxycarbonyl)amino]‐5‐oxopentanoate as key‐intermediate:the first synthesis of(S)‐2‐amino‐oleic acid

A general method for the synthesis of enantiopure non-natural alpha-amino acids is described. The key intermediate tert-butyl (2S)-2-[bis(tert-butoxycarbonyl)amino]-5-oxopentanoate was obtained from l-glutamic acid after suitable protection and selective reduction of the gamma-methyl ester group by DIBALH. Wittig reaction of this chiral aldehyde with various ylides led to a variety of delta,epsilon-unsaturated alpha-amino acids. This methodology was applied to the synthesis of (S)-2-amino-oleic acid.