Attachment of a styryl group to the 6-position of a protected penicillanic acid via cobaloxime-mediated radical alkyl-alkenyl cross coupling

Cobaloxime-catalyzed cross coupling of styrene with 6α-bromopenicillanic acid pivalolyl-oxymethyl ester (4) introduces a styryl group into the 6 position of the penicillanic acid nucleus. The method should be capable of introducing a variety of aryl-substituted alkenes into the 6 position. Such compounds may be useful as novel β-lactam antibiotics/β-lactamase inhibitors.