Microwave-Assisted Synthesis of Benzimidazole-Linked Indoline and Indole Hybrids from C-2 Linked (o-Aminobenzyl)benzimidazoles

Abstract

An efficient and novel synthesis of benzimidazole-linked indoline hybrids via an unconventional Pictet-Spengler-type condensation of C-2 linked (o-aminobenzyl) benzimidazoles with aldehydes and ketones under microwave irradiation has been explored. The key condensation step consists of acid-catalyzed imine generation followed by intramolecular C-C bond formation through unique reactivity of the benzimidazole moiety. The scope of this method is further extended to synthesize tetracyclic pyrroloindole benzimidazole-carboxylates through 2-carboxaldehydes.