Regioselective C–H Sulfonylation of 2<i>H</i>-Indazoles by Electrosynthesis

Abstract

This study reveals a transition-metal- and external oxidant-free electrochemical method for the C3–H sulfonylation of biologically diverse 2H-indazoles at room temperature and under ambient air. Using various sulfonyl hydrazides as the sulfonyl precursor, a series of sulfonylated indazole derivatives containing a broad spectrum of functional groups were synthesized in up to 92% yield. Mechanistic studies suggest a precedented radical pathway is operating in the electrochemical process.

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