Patent ID: 7541458

Claim:
A process for the preparation of cis-β-lactam (1A), the process comprising treating an imine (2) with a ketene acetal (3A) in the presence of a siloxide, M + O − SiR 51 R 52 R 53 , to form a reaction product mixture comprising cis- and trans-β-lactams (1A) and (1B), with the ratio of cis-β-lactam (1A) to trans-β-lactam (1B) in the reaction product mixture being at least 3:1 (cis:trans), wherein the cis- and trans-β-lactams (1A) and (1B), the imine (2), and the ketene acetal (3A) correspond to Formulae (1A), (1B), (2), and (3A), respectively: M + is a metal ion; X 1a and X 1b are trimethylsilyl or X 1a and X 1b are triethylsilyl; X 3 is phenyl, cyclopropyl, furyl, thienyl, pyridyl, or cyclopentyl; X 6 is trimethylsilyl or triethylsilyl; and —SiR 51 R 52 R 53 is trimethylsilyl or triethylsilyl.