Heterocycles. XI. Synthesis of 2-Amino-6-phenyl-3, 4-dihydro-1, 5-benzodiazocines

2-Amino-6-phenyl-3, 4-dihydro-1, 5-benzodiazocine derivatives (4) were synthesized by cyclization of 3-(2-amino-α-phenylbenzylideneamino) propionitriles (3). The reactivity of the diazocine (4a) was different from that of the structurally similar diazepine (6). Reaction of 4a with methylamine hydrochloride or with methanolic hydrogen chloride did not give the diazocine (9 or 11) but afforded the aminoethylquinazoline (10). The ultraviolet spectra indicated that the conjugation systems of 4a and 6 are different. Deuterium exchange reactions of 4a and 6 confirmed the presence of the equilibria 4a 4´a and 6 6´.