Photoaddition of ketones to imidazoles, thiazoles, isothiazoles and isoxazoles. Synthesis of their oxetanes

Abstract

Abstract Imidazole itself did not undergo photoaddition reactions with ketones. However, irradiation of 1‐acetyl and 1‐benzoylimidazole, and 1,1‐carbonyldiimidazole with benzophenone yielded oxetanes. On irradiation with carbonyl compounds, 1,2‐dimethylimidazole and 1‐benzylimidazole did not give oxetanes but a hydroxyaryl or hydroxyalkyl derivative. Thiazole itself did not yield any photoaddition product, but 2,4‐dimethylthiazole afforded oxetanes on irradiation with benzophenone and with 3‐benzoylpyridine. Irradiation of 2,4‐dimethylthiazole with acetophenone led to the formation of a dimeric material. On irradiation with benzophenone, 4‐methylisothiazole did not yield an oxetane but rather a hydroxyphenyl derivative. 3,5‐Dimethylisoxazole on irradiation with benzophenone and with 3‐benzoylpyridine gave oxetanes. Irradiation of 4,5‐dimethylisoxazole yielded similarly an oxetane with benzophenone