Polyaniline-sulfate salt as an efficient and reusable catalyst for the synthesis of 1,5-benzodiazepines and 2-phenyl benzimidazoles

Polyaniline-sulfate salt was used as an efficient catalyst for the preparation of benzodiazepines and 2-phenyl benzimidazoles in excellent yields. This method is applicable for the reaction of phenylenediamine with cyclic or acyclic ketones or aromatic aldehydes. The salient features of the present methodology are cheaper process, easy synthesis of stable catalyst, versatility and in addition, the catalyst can be easily recovered after completion of the reaction and reusable without affecting its activity.