Synthesis of 4-Aryl-2-benzazepine-1,5-diones by Photocyclization of N-(2-Arylethyl)phthalimides

Article abstract of DOI:10.1016/S0040-4020(01)87039-3

The photocyclization of N-(2-arylethyl)phthalimides to 4-aryl-2-benzazepine-1,5-diones is described.We found that the presence of electron donating substituents on the aryl ring (as in 10a and b) is necessary for the cyclization process to occur.The procedure also allowed synthesis of 2-benzazepinediones with a carboxylate group at C₃ (11c and d) which were obtained as 1:1 mixture of diastereoisomers.The results of irradiating phthalimides 12, which bear an oxygenated substituent at the benzylic position, depended on the nature of the substituent.Attempts to photocyclize N-(indan-2-yl)phthalimides 16 and the electron-rich phthalimide 23 failed.