3H-azepines and related systems. Part 5. Photo-induced ring expansions of o-azidobenzonitriles to 3-cyano- and 7-cyano-3H-azepin-2(1H)-ones

Article abstract of DOI:10.1016/S0040-4020(01)80706-7

Unlike other aryl azides bearing electron-withdrawing ortho-substituents, o-azidobenzonitriles on photolysis in aqueous-tetrahydrofuran yield mixtures of the expected 3-cyano- and the unexpected 7-cyano-3H-azepin-2(1H)-ones. In one instance ring contraction to a 2-azabicyclo[3.2.0]hept-6-ene-3-one is noted. X-ray crystallographic data for 7-cyano- and 4-chloro-7-cyano-3H-azepin-2-one, and for the azabicycloheptenone, are presented.