Abstract
Treatment of the N-unsubstituted 3-methyl-1H-1, 2-thieno[2, 3-c]diazepine (3) with ethyl chloroformate, acetyl chloride, or benzoyl chloride in benzene resulted in ring-conversion to give the corresponding 3-acyl-3H-1, 3-thieno[2, 3-d]diazepines (4), whereas similar treatment of the N-substituted thieno[2, 3-c]diazepine (6) gave the exo-methylene compound (7) and treatment of the fully unsubstituted thieno[2, 3-c]diazepine (8) gave the thieno[2, 3-b]pyridine derivatives (9) and (10). On the other hand, the N-unsubstituted 3-methyl-1H-1, 2-benzo[c]diazepines (16), upon treatment with ethyl chloroformate in benzene, gave the exo-methylene compounds (17), and in the case of the diazepines (16b, c) having an electron-donating group in the 7-position, the 3-acyl-3H-1, 3-benzo[d]diazepines (19) were also formed. The mechanisms of these acylations are discussed.
