Rapid Two-Step Synthesis of Benzimidazo[1 ',2 ':1,5]-pyrrolo[2,3-c]isoquinolines by a Three-Component Coupling Reaction

Abstract

A two-step, three-component coupling reaction on ionic liquid supported 2-cyanomethylbenzimidazoles, methyl 2-formylbenzoate, and isocyanides under microwave activation is explored. Knoevenagel condensation of 2-cyanomethylbenzimidazole with methyl-2-formylbenzoate in the presence of piperidine catalyst is followed by [4 + 1] cycloaddition with an isocyanide in the next step. Consequent intramolecular delta-lactam formation allows rapid construction of novel aza-pentacycles, benzimidazo [1',2':1,5]pyrrolo [2,3-c]isoquinolines.