NOVEL PHOTOCYCLIZATION OF BETA,GAMMA-UNSATURATED OXIMES

Previously, beta,gamma-unsaturated oximes were thought to be photochem ically unreactive. The present study reports the first three examples of photocyclization of beta,gamma-unsaturated ketoximes to yield 4,5-d ihydroisoxazole derivatives. Typically, acetophenone-sensitized irradi ation of 3,3-dimethyl-5,5-diphenylpent-4-en-2-one oxime (2) affords ph enylmethyl)-3,4,4-trimethyl-4,5-dihydroisoxazole (3) in 38% yield. A s ingle-electron transfer (SET) mechanism is proposed to account for the cyclization.