Oxidative Cleavage ofβ-Keto Sulfones via Nitrous Acid

Abstract

The reaction of nitrous acid with 1-aryl-2-(arylsulfonyl)ethanones3a–eafforded the unexpected arenecarboxylic acids12a–e, formic acid14, and benzene/4-toluenesulfinic acid15a,bthrough oxidative cleavage reaction. 4-Chlorobenzoic acid (12a), [1,1′-biphenyl]-4-carboxylic acid (12b), 2-naphthoic acid (12c), 2-thiophenecarboxylic acid (12d), and 2-benzofurancarboxylic acid (12e) were isolated in 72%, 62%, 55%, 58%, and 62% yields, respectively. The reported mechanistic pathways proposed the production of 1-aryl-2-(phenyl/tolylsulfonyl)ethane-1,2-dione7instead of arenecarboxylic acids12. A mechanistic pathway to explain the reaction of nitrous acid with 1-aryl-2-(arylsulfonyl)ethanones3a–ewas suggested. In this pathway, the intermediate 1,2-oxazete10lost benzene/4-toluenesulfinic acid15to produce 1,2-oxazet-3-one11. Ring cleavage of the latter intermediate afforded the arenecarboxylic acids12.