S. Kanwar et al., Stereocontrolled synthesis of beta-lactams via Staudinger reaction betweenphenoxyketenes and chiral imines, J INDIAN CH, 78(3), 2001, pp. 137-141
Chiral Schiff bases derived from esters of valine and alanine have been sho
wn to be useful intermediates for the stereoselective synthesis of beta -la
ctams. Staudinger reaction between these compounds and phenoxyketenes, gene
rated in situ, from the corresponding acid chlorides in the presence of tri
ethylamine, provides a mixture of diastereomeric cis-beta -lactams. Attempt
s have been made to separate them using column chromatography and their rat
ios determined through H-1 NMR data.