Synthesis of Benzoaryl-5-yl(2-hydroxyphenyl)methanones via Photoinduced Rearrangement of (E)-3-Arylvinyl-4H-chromen-4-ones.

A concise and efficient photoinduced rearrangement of (E)-3-arylvinyl-4H-chromen-4-ones for the synthesis of benzoaryl-5-yl(2-hydroxyphenyl)methanones is described. Benzoaryl-5-yl-(2-hydroxyphenyl)methanones were obtained in 77-95% yields via the irradiation of (E)-3-arylvinyl-chromones in the 95% EtOH with a high-pressure mercury lamp at room temperature under Ar atmosphere. The reported method provides a novel procedure for the synthesis of α,α'-diaryl ketone derivatives without addition of any transition metals and oxidants or other additives. A plausible mechanism was proposed, and the rearrangement product was characterized by NMR, HRMS, and X-ray.