Purely Chemical Approach for Preparation of D-α-Amino Acids via (S)-to-(R)-Interconversion of Unprotected Tailor-Made α-Amino Acids

Unnatural (R)-alpha-amino acids (alpha-AAs) are in growing demand in the biomedical research and pharmaceutical industries. In this work, we present development of a purely chemical approach for preparation of (R)-alpha-AAs via (S)-to-(R)interconversion of natural and tailor-made (S)-alpha-AAs. The method can be used on free, unprotected a-AAs and features a remarkable structural generality including substrates bearing tertiary alkyl chains and reactive functional groups. These attractive characteristics, combined with simplicity of reaction conditions and virtually complete stereochemical outcome, constitute a true methodological advance in this area, rivaling previously reported chemical and biocatalytic approaches.