Enantiopure N-Tosylazetidines from α-Amino Acids

Abstract

Reported is a very simple, practical, and general synthetic sequence to chiral 2- and 2,4-disubstituted N-tosylazetidines starting from readily available α-amino acids which pro­ceeds in moderate to good overall yields and with high enantiopurity (>99%). Homologation is achieved through a reduction, tosylation, and NaCN substitution sequence which avoids the Arndt-Eistert homologation that suffers from the occurrence of side reactions when applied to α-amino acids (K. Pluciska, B. Liberek Tetrahedron 1987, 43, 3509-3517).