A practical FeCl3/HCl photocatalyst for versatile aliphatic C–H functionalization

The practical and diversified functionalization of ubiquitous C(sp3)–H bonds is an economically attractive yet chemically challenging approach to build molecular complexity from abundant chemical raw materials. Herein, we have identified a very robust and practical FeCl3/HCl photocatalytic system that enables greatly efficient C–H alkylation, oxidation, chlorination, fluorination, amination, alkynylation, and sulfonylation with total turnover number (TON) of up to 9,900. The aliphatic C–H activation is mediated by chlorine radical, in situ generated from a photoactive tetrahedral [FeIIICl4]− via ligand-to-metal charge transfer excitation, and the use of HCl as co-catalyst significantly improves the total TON by more than one order of magnitude.