Visible-Light-Promoted Activation of Unactivated C(sp 3 )-H Bonds and Their Selective Trifluoromethylthiolation.

Selective functionalization of ubiquitous C(sp ³ )-H bonds using visible light is a highly challenging yet desirable goal in organic synthesis. The development of such processes relies on both rational design and serendipitous discoveries from innovative tools such as screening technologies. Applying a mechanism-based screening strategy, we herein report photoredox-mediated hydrogen atom transfer catalysis for the selective activation of otherwise unactivated C(sp ³ )-H bonds, followed by their trifluoromethylthiolation, which has high potential as a late-stage functionalization tool. The generality of this method is exhibited through incorporation of the trifluoromethylthio group in a large number of C(sp ³ )-H bonds with high selectivity without the need for an excess of valuable substrate.