Rate enhancement in the reduction of (2,3)-α- and (2,3)-β- methylenepenam β-sulfoxides

The ease of reduction of (2,3)-α-methylenepenam β-sulfoxides, (2,3)- β-methylenepenam β-sulfoxides and bicyclic penam β-sulfoxides to the corresponding sulfides, using potassium iodide and trifluoroacetic anhydride in acetone or N,N-dimethylformamide, was measured. The results indicate that in general the rate of reduction of both (2,3)-α- and (2,3)-β- methylenepenam β-sulfoxides is several orders of magnitude greater than the rate of reduction of bicyclic penam β-sulfoxides. A mechanistic explanation to account for this observation is advanced.