Substrate-controlled regioselective C(sp2)–H sulfonylation of ortho-aminophenols†

Cu(II)-catalyzed highly regioselective C(sp²)–H bond sulfonylation of ortho-aminophenols with sulfonyl hydrazides to obtain arylsulfones is described. The sulfonyl radical generated from sulfonyl hydrazide via single-electron transfer (SET) forms a C–S bond with the aminophenol via a Cu(II)/Cu(III) catalytic cycle. The synthetic transformations and photophysical properties of the synthesized aryl sulfones have also been investigated.