Phototransformations of 4,5-diphenylisoxazole

Sunlight photolysis of 4,5-diphenylisoxazole (1) in methanol sensitized by benzophenone gives 4,4′,5,5′-tetraphenyl-2,2′-bioxazole, (4). On irradiation at 350nm in acetone or at 253.7 nm in absolute alcohol, isoxazole (1) yields α-benzoylphenylacetonitrile (6) besides the expected phenanthro 9,10-d]-oxazole (5). The bioxazole and the ketonitrile have been identified by single crystal X-ray studies.