Syntheses of Benzo[ e ]-1,3,4-triazepine Derivatives from 2-Aminobenzophenones

2-Aminobenzophenone semicarbazones (II) or 2-aminobenzophenone phenylhydrazones (III) were cyclized to 3,7-disubstituted 5-phenyl-2,3-dihydro-1H-benzo[e]-1,3,4-triazepines (IV) by treating them with paraformaldehyde. On the other hand, 3,7-disubstituted 2-oxo-5-phenyl-2,3-dihydro-1H-benzo[e]-1,3,4-triazepines (V) were prepared by the fusion of II at 190–195°C or by the treatment of III with phosgene. In the latter reactions, 1-carboxy derivatives (VI) of V were obtained by using two equimolar amounts of phosgene. Vf was treated with sodium ethoxide to give a ring-cleavage product, 5-chloro-2-ethoxycarbonylaminobenzophenone phenylhydrazone (VIIIf), which was then fused to afford 6-chloro-1,2-dihydro-2-oxo-4-phenylquinazoline (VIIb).