Synthesis of Optically Active 4-Alkoxycarbonyl-β-lactams from L-Aspartic Acid

Abstract
Cyclization of L-aspartic acid to (S)-4-benzyloxycarbonyl-2-azetidinone followed by transesterification of this compound in the presence of titanium (IV) tetrabutoxide proved to be an exceedingly efficient method of general application for the preparation of (S)-4-alkoxycarbonyl-β-lactams.