Direct conversion of sulfinic acid to sulfonic acid derivatives.

Abstract

The reaction of sulfinic acid (1) with methanol in the presence of NCS-DMS gave methyl sulfinate (2) and methyl sulfonate (3) in 22% and 45% yields, respectively. Similarly, 1 reacted with morpholine under the same conditions to give the corresponding sulfinamide (5) and sulfonamide (6) in 23% and 50% yields. In these reactions, the disulfone (4) was also obtained as a minor product in some cases. The formation of sulfonic acid derivatives and disulfone was found to proceed through the intermediate formation of the sulfonyl chloride (7). The formation mechanism of sulfinic acid derivatives is also discussed.