Molecualr Structures of 8-Chloro-6-phenyl-4H-8-triazolo [4, 3-a] [1, 4] benzodiazepine, 2-Acetoxyamino-4-acetyl-8-chloro-3, 4-dihydro-6-phenyl-1, 4, 5-benzotriazocine and 8-Chloro-4, 11-diacetyl-4, 11-dihydro-2-methyl-6-phenyloxazolo [4, 5-b]-[1, 4, 5] benzotriazocine. Formation of an Eight-Membered Ring from a Quinazoline Derivative on Treatment with Hydrazine evidenced by X-Ray Analysis

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7-Chloro-2-hydrazino-5-phenyl-3H-1, 4-benzodiazepine was synthesized by the reaction of 2-amino-7-chloro-5-phenyl-3H-1, 4-benzodiazepine with hydrazine.³⁾ The compound was, however, obviously different from the one to which the same structure was assigned by Derieg, et al.⁴⁾ In order to distinguish between them, an X-ray analysis was carried out on some crystalline derivatives of these compounds and the structure of Derieg's compound was revised to 2-amino-8-chloro-3, 4-dihydro-6-phenyl-1, 4, 5-benzotriazocine. The conformation of the 1, 4-benzodiazepine clarified in the present analysis resembled to the 1, 4-benzodiazepine derivatives previously reported.^5-7) But the conformations of the 1, 4, 5-benzotriazocines, especially the arrangement of the two aromatic rings and the positioning of electron-donating groups in each molecule, were not identical to those of 1, 4-benzodiazepines. Such conformational difference may account for the differences in pharmacological activities of these compounds.