STEREOCONTROLLED SYNTHESIS OF N-VINYL-BETA-LACTAMS, N-(1'-PROPENYL)-BETA-LACTAMS, AND N-UNSUBSTITUTED-BETA-LACTAMS FROM 2-AZA-1,3-BUTADIENES VIA THE STAUDINGER REACTION

2-Aza-1,3-butadienes 2 and 5 were synthesized in good yields and on a large scale. Reaction of 2 and 5 with acid chlorides in the presence of triethylamine (Staudinger reaction) resulted in the high-yielding formation of N-vinyl- and N-(1'-propenyl)-beta-lactams. Excellent cis-stereoselectivity was observed in the reaction of 2-aza-1,3-butadienes 2 and 5 with Bose-Evans ketenes and Sheehan ketenes, whereas reaction with a Moore ketene gave, as expected, a trans beta-lactam. N-Formyl, N-vinyl, and N-(1'-propenyl) groups at the beta-lactam nitrogen could be cleaved oxidatively in one step and in good yields by treatment with potassium permanganate. It was also found that the N-vinyl group can be removed successfully under hydrolytic, conditions to yield N-unsubstituted-beta-lactams.