Oxidative Cleavage of β-Keto Sulfones via Nitrous Acid

Abstract EN

The reaction of nitrous acid with 1-aryl-2-(arylsulfonyl)ethanones 3a–e afforded the unexpected arenecarboxylic acids 12a–e, formic acid 14, and benzene/4-toluenesulfinic acid 15a, b through 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-dione 7 instead of arenecarboxylic acids 12.

A mechanistic pathway to explain the reaction of nitrous acid with 1-aryl-2-(arylsulfonyl)ethanones 3a–e was suggested.

In this pathway, the intermediate 1,2-oxazete 10 lost benzene/4-toluenesulfinic acid 15 to produce 1,2-oxazet-3-one 11.

Ring cleavage of the latter intermediate afforded the arenecarboxylic acids 12.