PALLADIUM-CATALYZED CARBONYLATIVE [2-3-ALKENYL OR TRANS-3-ALKENYL BETA-LACTAMS(2] CYCLOADDITION FOR THE STEREOSELECTIVE SYNTHESIS OF EITHERCIS)

A new potential alkenylketene equivalent, prepared without use of a ca rboxylic acid or an activated derivative, has been exploited. Palladiu m-catalyzed carbonylation of an allyl phosphate in the presence of an imine and a tertiary amine under CO pressure (30 kg cm(-2)) stereosele ctively gave either a cis-or trans-3-alkenyl beta-lactam in high yield . The stereochemical outcome strongly depends on the nature of the imi ne employed. Imines conjugated with a carbonyl such as a ketone or an ester stereoselectively produce cis-beta-lactams at room temperature, whereas imines unconjugated with a carbonyl group exclusively afford t rans-beta-lactams at 70 degrees C.