BINAP-Accelerated\nCopper-Mediated Photochemical Late-Stage\nTrifluoromethylation of Arenes

Site-selective and late-stage C–H trifluoromethylation\n(including\npentafluoroethylation) of arylthianthrenium salts using <i>in\nsitu</i> generated CuCF<sub>3</sub> from Ruppert–Prakash\nreagent under visible light was found to be significantly accelerated\nby a catalytic amount of <i>rac</i>-BINAP, allowing the\nreaction to complete within 15 min under very mild conditions without\nusing any additional photoredox catalysts. The process showed a broad\nsubstrate scope, high efficiency, and excellent regioselectivity,\nwhich holds the promise to accelerate the discovery of fluorinated\nmedicinal compounds.