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.