The Pschorr cyclization. III. The synthesis of Dibenz[c,e]azepines

Abstract

The copper-catalysed decomposition of diazonium salts derived from N- mesyl-dibenzylamines has been examined. 2-Amino-N-mesyldibenzylamine (8a) gave 6-mesyl-6,7-dihydro-5H-dibenz[c,e]azepine (9a) as the major product, together with benzaldehyde and N-benzylmethanesulphonamide (6a). Derivatives of the amine (8a) bearing 4?-methyl (8b), 4?-chloro (8c), 2?-chloro (8d), and 4?-methoxy (8e) substituents were cyclized to the appropriately substituted dibenz[c,e]azepines (9b-e). The corresponding aldehydes (10b-e) and N-benzylmethanesulphonamide (6a) were also isolated from these reactions. In addition, the compounds (8b), (8c), and (8d) gave 2-(N-mesylaminomethyl)-4?-methylbiphenyl (11b) and the 4?-chloro (11c) and 2?-chloro (11d) derivatives, respectively, as minor products. Possible mechanisms for the formation of the byproducts of the cyclization reactions are discussed. The isomeric amines, o-amino-N-benzenesulphonyl-N-methylbenzylamine (12) and N-(o-aminobenzenesulphonyl)-N-methylbenzylamine (13), were cyclized by copper-catalysed decomposition of their respective diazonium salts to give 6-methyl-5H-dibenzo[d,f]thiazepine 7,7-dioxide (14) as the major product of the reactions.