One-pot procedure for the synthesis of diverse derivatives of novel heterocyclic system benzo[e]pyrazolo[5 ,1 :2,3]pyrimido[5,4- b][1,4]diazepine

The 1,4-diazepine and 1,4-benzodiazepine structures have been found in the naturally occurring products and are significant biomolecules in medicinal chemistry with a wide range of biological and pharmacological activities such as antibiotic, [1] antimalarial, [2] anti-HIV, [3] and anticancer.[4] The benzodiazepines are also the most widely prescribed minor tranquilizers in current use, and they are known to act on the central nervous system. Therefore, benzodiazepines are an important class of psychotherapeutic compounds. [5]Due to the widespread biological activities of fused heterocyclic systems, in this study, we synthesized various derivatives of benzo[e]pyrazolo[5 ,1 :2,3]pyrimido[5,4- b][1,4]diazepine as a novel heterocyclic system. In this one-pot protocol, the desired products (3a-h) were obtained through the cyclocondensation of diverse synthesized 2-amino-N-alkylbenzamides (1a-h) with 6-bromo-7-chloro-2-(ethylthio)-5- methylpyrazolo[1,5-a]pyrimidine-3-carbonitrile (2) in the presence of K2CO3 in DMF. The true regioisomers of heterocyclization were also investigated.