Visible-light mediated trifluoromethylation of p-quinone methides by 1,6-conjugate addition using pyrylium salt as organic photocatalyst.

A transition metal free visible light mediated organo photoredox catalyzed trifluoromethylation of p -quinone methides (p -QMs) to construct fluoro-analogs of dichlorodiphenyltrichloroethane (DDT) is reported using a bench stable, inexpensive Langlois reagent as a trifluoromethyl radical source. This protocol could generate a benzylic C(sp 3 )-CF 3 bond with excellent yield under mild reaction conditions using 1,6-conjugate addition/aromatization of trifluoromethyl radical in the absence of any external additives. Further, we demonstrate di-trifluoromethylation and gram scale synthesis of this reaction. Organo photoredox catalyzed trifluoromethylation of p -quinone methides (p -QMs) to construct fluoro-analogs of dichlorodiphenyltrichloroethane (DDT) is reported. This protocol could generate a benzylic C(sp 3 )–CF 3 bond with excellent yield. We also demonstrate the di-trifluoromethylation of p -QM. Image 1 [ABSTRACT FROM AUTHOR]