Synthesis of β- and γ-Hydroxy α-Amino Acids via Enzymatic Kinetic Resolution and Cyanate-to-Isocyanate Rearrangement

A new strategy for stereoselective preparation of all four isomers of β- and γ-hydroxy α-amino acids is presented. The developed procedure is based on enzymatic kinetic resolution and cyanate-to-isocyanate rearrangement as key steps. Stereocontrol is achieved by proper choice of the starting hydroxyacid, the course of kinetic resolution, and the stereospecific sigmatropic rearrangement step, which proceeds with full chirality transfer.