Synthesis and β-Lactamase Inhibitory Evaluation of Novel 6α- Halo-2β-chloromethyl-2α-methylpenam-3α-carboxylic Acids and Their Sulfones and 6α-Halo-2β- mercaptobenzothiazolylmethyl-2α-methylpenam-3α-carboxylic Acids.

Abstract The synthesis and the inhibitory activity against β-lactamase I from Bacillus cereus is described for a new series of 6α-bromo, chloro or fluoro-2β-chloromethyl-2α-methylpenam-3α-carboxylic acids (5a-c) and their corresponding sulfones 6a-c and 6α-bromo, chloro or fluoro-2β-mercaptobenzothiazolylmethyl-2α-methylpenam-3α-carboxylic acids (8a-c). Among the novel compounds, the highest activity was expressed by 6α-chloro-2β-chloromethyl-2α-methylpenam-3α-carboxylic acid 1,1-dioxide (6b).