A Multicomponent Domino Reaction and in situ Aerobic Oxidation Sequence for the First One-Pot Synthesis of Polycyclic Benzimidazoles from 1,3-Dicarbonyl Derivatives

A facile one-pot synthesis of functionalized pyrido[1,2-a]benzimidazoles is described via a molecular-sieves-promoted three-component domino reaction and in situ aerobic oxidation sequence from 1,3-dicarbonyls, aromatic o-diamines and unsaturated aldehydes. This environmentally friendly sequence does not require any harmful reagents, and liberates water as the only by-product. The desired products are obtained in good to excellent yields and generally with high purity, after simple filtration.