Selective trifluoromethylation and alkynylation of tetrahydroisoquinolines using visible light irradiation by Rose Bengal

A convenient and efficient method for oxidative coupling of tetrahydroisoquinoline derivatives with trimethyl(trifluoromethyl)silane and terminal alkynes to 1-trifluoromethylated or 1-alkynylated tetrahydroisoquinolines via CH activation was developed using visible light irradiation. The protocol uses Rose Bengal as the catalyst, air as terminal oxidant, and the trifluoromethylation or alkynylation was selectively performed at the α-position of nitrogen under extremely mild conditions.