Highly Efficient Stereoconservative Amidation and Deamidation of α-Amino Acids

An overall stereoconservative protection and deprotection method of amino and carboxyl groups is presented. N-Phthaloyl N ‘-alkyl secondary amides of α-amino acids can be generated from corresponding N-phthaloyl amino acids by coupling reaction of N-alkylamines using mixed anhydride method. These secondary amides can be transformed by thermal rearrangement of intermediate nitrosoamides to O-alkyl esters with retention of configuration and excellent yields.