Description Under a dual catalytic copper/photoredox manifold, the Mes-Umemoto reagent has been demonstrated to be an excellent photocatalyst for the trifluoromethylation of alkyl halides and aryl halides to yield alkyl-CF3and aryl-CF3in high yields. In both cases, these reactions exhibit wide substrate scope with good functional group tolerance. More specifically, a variety of 5-membered and 6-membered heteroaryl halides can be readily converted to the corresponding trifluoromethylheteroarenes under mild conditions. For trifluoromethylation reactions, use with dMesSCF3(901466) and supersilanol (902489).