A facile one-step synthesis of chromeno[4,3-b]pyridine derivatives promoted by niobium pentachloride

Abstract

Chromenes are part of an important class of heterocyclic compounds, natural or synthetic, and have many biological and chemical applications. Among them, chromenopyridines has arisen as a promising material for pharmacological applications. In this work is described a simple and cost-effective method to synthesize chromeno[4,3-b]pyridine derivatives from multicomponent reaction between 4-aminocoumarin, benzaldehyde derivatives, and ethyl benzoylacetates catalyzed by niobium pentachloride. The new method provides good yields with reasonable reaction times, under mild reaction conditions.