Non-directed copper-catalyzed regioselective C-H sulfonylation of phenothiazines

We develop a simple and general method for sulfonylation of phenothiazines under Cu(I) catalysis. The broad scope of aryl/alkyl sulfonyl chlorides was applicable to produce C3 sulfonylation products of phenothiazines in moderate to good yields. The further transformation of the sulfonylation products was successful, which afforded valuable polyheterocycles.