Stereocontrolled synthesis of β-lactams via Staudinger reaction between phenoxyketenes and chiral imines

Department of Chemistry, Panjab University, Chandigarh-160 014, India E-mail : sharmasd@panjabuniv.chd.nic.in Fax : 91-172-541409 Manuscript received 13 March 2000, revised 18 August 2000, accepted 6 September 2000 Chiral Schiff bases derived from esters of valine and alanine have been shown to be useful intermediates for the stereoselective synthesis of β-lactams. Staudinger reaction between these compounds and phenoxyketenes, generated in situ, from the cor­responding acid chlorides in the presence of triethylamine, provides a mixture of diastereomeric cis-β-lactams. Attempts have been made to separate them using column chromatography and their ratios determined through 1H NMR data