Summary In the presence of air, light (high pressure mercury lamp) and iodine as sensitizer, benzene solution of arylthiazoles 2, 3 and 13 (see scheme I) were converted into a mixture of photoisomers and aryloxazoles (see scheme 2). Upon shorter times of irradiation under oxygen in chloroform containing methylene blue as a sensitizer 2, 4, 5-triphenylthiazole (7) is converted in 2, 4, 5-triphenyloxazole.
