Direct C–H sulfonylation of hydrazones involving the insertion of SO2

Abstract

A three-component reaction of aldehyde-derived hydrazones with DABSO and aryldiazonium tetrafluoroborates is described. By using organic DABSO as the source of SO₂, this straightforward sulfonylation tactic provides an elegant access to (E)-sulfonylated hydrazones in moderate to excellent yields. Moreover, the sulfonylation of hydrazones can also be achieved under photocatalyzed conditions by using sulfonyl chlorides as the active sulfonylating reagents.