Construction of Quinazolin(thi)ones by Brønsted Acid/Visible-Light Photoredox Relay Catalysis

A relay Bronsted acid/visible-light photoredox catalysis strategy for the synthesis of quinazolin(thi)ones is developed. In this procedure, 2-aminoacetophenones and iso(thio)cyanates undergo Bronsted acid catalyzed [4+2] annulation, followed by photocatalyzed C-C bond cleavage reaction. A wide range of diversely substituted quinazoline-2,4-diones and quinazoline-2-thione-4-ones were synthesized under mild conditions. The protocol features eco-benign energy source and solvent, metal-free catalysts, simple starting materials and air as green oxidant.