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. (Figure presented.).
- benzimidazole-linked indoles
- benzimidazole-linked indolines
- indoline synthesis
- unconventional Pictet–Spengler reaction