NOVEL PHOTOCHEMICAL BEHAVIOR OF THE OXIMES AND HYDRAZONES OF BETA,GAMMA-UNSATURATED CARBONYL-COMPOUNDS

A study of the photochemical reactivity of a series of beta,gamma-unsa turated oximes and hydrazone derivatives under tripler sensitized cond itions has been carried out, The oximes 3c, 4a and 4c cyclize to the c orresponding dihydroisoxazoles 5c, 6a and 6c while the tosyl hydrazone 8a affords the dihydropyrazole 9a. An intramolecular single electron- transfer mechanism from the alkene moiety to the oximino group, in the case of the oximes 3c, 4a and 4c, and to the tosyl group for the tosy l hydrazone 8a, is proposed to account for these results, Grimes and h ydrazine derivatives from aldehydes behave differently, Thus, the oxim e 3d yields the cyclopropyl oxime 10 by an aza di-pi-methane (ADPM) re arrangement while the aldoxime 3e gives a mixture of the corresponding dihydroisoxazole 5d and cyclopropane 11a resulting from an ADPM proce ss, Irradiation of the hydrazine derivatives 8b, 8c and 8d gives a mix ture of the corresponding dihydropyrazoles 9b, 9c and 9d and the cyclo propanes 11b, Ile and 11d, respectively, However, under the same exper imental conditions, dihydronaphthalene derivatives such as the oxime 1 2a and the tosyl hydrazone 12b undergo ADPM rearrangements exclusively , affording the cyclopropanes 13a and 13b, respectively, Sensitized ir radiation of the tosyl hydrazone 12c yields the cyclopropane 13c, as t he major product, In this instance a small amount of the hexahydrophen anthroline 14, resulting from an endo cyclization is also formed, The influence of substitution on the outcome of the reaction is discussed.