Synthesis of N-substituted pyrrolo[1,2-a][1,4]benzodiazepines

Abstract

In the framework of our study on the use of furan-containing substrates in the synthesis of condensed heterocyclic systems, we continued our investigation of the transformations of N-furfurylanthranilamides in acid media. In an attempt to effect the recyclization of tertiary N-furfurylanthranilamides and 3-aminothieno[2,3-b]pyridienecarboxamides by the action of a mixture of glacial acetic acid and hydrochloric acid, we found that the furfuryl fragment is lost rather than opening of the furan ring [1]. In the present communication, we show that the major reaction pathway upon treatment of amides 1 with ethanolic HCl is recyclization of the furan ring to form the pyrrolo[1,2-a]diazepine system.