A short, versatile chemical synthesis of l- and d-amino acids stereoselectively labelled solely in the beta position

Abstract

L- and D-Amino acids which are stereoselectively labelled solely either in the 3-pro-R or in the 3-pro-S-positions have been prepared by a relatively short chemical synthesis in ee of 81 to 86%. This involves Sharpless' aminohydroxylation and cyclisation with inversion of stereochemistry at C-2 to give the stereoselectively labelled D- and L-aziridines 10a and 10b, and 8a and 8b. These have previously been modified and cleaved with inversion of stereochemistry at C-3 using a number of nucleophiles to give a large variety of protected amino acids. Synthesis of the labelled D- and L-β-chloroalanines 22a and 22b and 25a and 25b is described here.