A Donor–Acceptor Covalent Organic Framework for the Metal-Free Photocatalytic Trifluoromethylation of Arenes and Heteroarenes

The direct trifluoromethylation of arenes and heteroarenes is important for the pharmaceutical and agrochemical industries. Finding metal-free heterogeneous catalysts that can achieve this transformation photocatalytically remains a challenge. Herein, we report the synthesis and photocatalytic properties of an imine-linked donor–acceptor (D–A) covalent organic framework (COF) containing benzotrithiophene (BTT) and 2,5-diphenyl-thiazolo[5,4-d]thiazole (DTTz) units. The BTT-DTTz-COF exhibited great absorption of visible light and promoted the direct trifluoromethylation of arenes and heteroarenes in the presence of Langlois reagent under photoirradiation. The BTT-DTTz-COF exhibited excellent recyclability and yields as high as 85%. This work highlights a rare example of using a metal-free D–A COF for the photoinduced trifluoromethylation of arenes and heteroarenes.