A facile IL–DMSO assisted synthesis of 5-, 6-, and 7-membered benzo-annelated cyclic guanidines

A new and facile IL–DMSO assisted method has been developed for the synthesis of biologically important cyclic guanidines like 2-aminobenzimidazole, 2-imino-4-quinazolinone, and 2-imino-5-benzotriazepinones at ambient temperatures. The desired products could be obtained by microwave irradiation32 also, but at elevated temperatures. A plausible mechanism for catalysis has been proposed.