SYNTHESIS OF A MASKED P-QUINONE METHIDE BETA-LACTAM AS AN ACTIVE METABOLITE OF NOCARDICINS

Nocardicin A analogues 30, 34, and 38 as well as the highly strained q uinone methide 43 were synthesized. beta-Lactam 34 was found biologica lly active against several Gram-negative microorganisms in vitro; pyri dinium N-oxide derivative 38 possessed activity against Gram-positive S. aureus bacterium. Masked p-quinone methide beta-lactam 43 exhibited significant antimicrobial activity in vitro. A mechanism involving an oxidation in vivo is proposed for the unprecedented biological proper ties of nocardicins.