A STUDY ON THE SCOPE OF THE PHOTOCHEMICAL 1,3-MIGRATION OF OXIMINO GROUPS IN BETA,GAMMA-UNSATURATED OXIMES AND OXIMES DERIVATIVES

While the aza-di-pi-methane rearrangement is the normal photoreactive behaviour of beta,gamma-unsaturated imines and oxime acetates, the res ults obtained in this study show that 1,3-migrations of acetoxyimino g roups in beta,gamma-unsaturated oxime acetates takes place only when a ll the parameters are correct. The rearrangement takes place when ther e is a quaternary carbon separating the two pi-systems and when one of the radical centres in the intermediate cyclobutyl 1,4-biradical is s tabilized by conjugation with a phenyl ring. Suppression of the free r otor effect also helps to promote the reaction. These criteria are ful filled in compounds 1a and 7a. The reaction was extended to the beta,g amma-unsaturated oximes 1b and 7b where again the 1,3-migration of the oximino group took place.