Site-Selective C(sp3)-H Functionalization of Fluorinated Alkanes Driven by Polar Effects Using a Tungstate Photocatalyst

The TBADT-catalyzed C(sp(3))-H functionalization of perfluorophenyl- and perfluoroalkyl-substituted alkanes was studied to determine how the fluorous substituents affect site-selectivity. Alkylation of alkyl-substituted perfluorobenzene avoids alpha-C-H bonds, unlike their alkylbenzene counterparts, allowing site-selective functionalization of C-H bonds remote to the aromatic ring. Alkylation of alkanes having a perfluoroalkyl group also avoided alpha-C-H bonds. Radical polar effects in the S(H)2 transition states could explain this avoidance of alpha-C-H functionalization.