Microwave-Assisted Combinatorial Synthesis of Polysubstituent Imidazo[1,2-a]quinoline, Pyrimido[1,2-a]quinoline and Quinolino[1,2-a]quinazoline Derivatives

A series of unusual fused heterocyclic compound derivatives, consisting of a pyridine and a imidazole or pyrimidine core, with a bridgehead nitrogen, were successfully synthesized by a microwave-assisted, three-component domino reaction of aldehydes, enaminones, and malononnitrile. In this one-pot reaction, up to five new bonds were formed accompanied by generating the lactam group. This method has the advantages of short synthetic route, operational simplicity, increased safety for small-scale high-speed synthesis, and minimal environment impact.