Sodium sulphide promoted synthesis of fused quinoline at room temperature

Abstract

A novel, simple and eco-friendly strategy for the synthesis of thiopyrano[4,3-b]quinolin-1-ones and pyrrolo[3,4-b]quinolin-1-ones from 2-alkynylquinoline-3-carbonitriles and sodium sulphide (Na₂S·9H₂O) under catalyst-free conditions at room temperature has been described. In this reaction, a readily available inorganic salt (Na₂S·9H₂O) serves as the sulphur source and leads to the generation of diverse functionalized thiopyrano[4,3-b]quinolin-1-ones and pyrrolo[3,4-b]quinolin-1-ones in moderate to excellent yields through sulfuration, annulation, and aerial oxidation.