Sulfamic Acid Catalyzed Atom Economic, Eco‐friendly Synthesis of Novel 7‐(Aryl)‐10‐thioxo‐7,9,10,11‐tetrahedro‐6H‐pyrimido‐[5′4′:5,6]pyrano[3,2‐c]quinoline‐6,8(5H)‐dione and its Derivatives

Abstract

A series of novel 7‐(3‐chloro‐phenyl)‐10‐thioxo‐7,9,10,11‐tetrahedro‐6H‐pyrimido‐[5′4′:5,6] pyrano[3,2‐c]quinoline‐6,8(5H)‐dione derivatives have been synthesized through the multi‐component condensation of aromatic aldehydes, barbituric acid, and 2,4‐dihydroxy quinoline, using heterogeneous sulfamic acid catalyst in water‐ethanol (4:1) solvent system under reflux condition. The present protocol is endowed with charming description such as green synthetic procedure, short reaction time, easy work‐up procedure, and excellent yield and high atom economy of pyranoquinoline derivatives. In this study, sulfamic acid is used as a heterogeneous catalyst that is easily recoverable and recyclable. The proposed multi‐component reaction has been studied with detail mechanism and spectroscopic data. This is one of the potential greener synthetic approaches to build up the series of pyranoquinoline heterocycles.