5,5,6-Fused tricycles bearing imidazole and pyrazole 6-methylidene penems as broad-spectrum inhibitors of β-lactamases

A series of novel 5,5,6-fused tricyclic-6-methylidene penems have been synthesized and were shown to be potent, broad spectrum β-lactamase inhibitors against class-A, class-B, and class-C enzymes. The present paper deals with the synthesis and structure–activity relationships of these derivatives.