Copper‐Mediated Relay Strategy Using Chlorination/Oxidation: An Effective Synthesis of Functionalized Coumarin Derivatives

Abstract

Chromene-fused heterocyclic compounds have shown fascinating biological and physiochemical properties and thus, the design and development of chromene-fused heterocyclic molecules is of significant interest in the field of synthetic organic chemistry. We report an innovative ligandand additive-free synthetic approach of 4-(phenylethynyl)-2Hchromene-3-carbaldehyde with phenylacetylenes has been described through sequential chlorination, benzannulation, benzylic sp 3 CÀ H bond functionalization, and ether oxidation for the formation of chloro-substituted-9-phenyl-6H-benzo[c]-chromen-6-ones with readily available chemicals under onepot, base-free conditions using CuCl 2 as sustainable catalyst. In this regioselective approach, we defined a reasonably longer cascade, which reveals the multiple role of chlorine as chlorine supplier, Lewis acid catalyst and oxidation rate promoter that tolerates a broad substrate scope and allows good product yields. The authenticated mechanism proceeds in a cascading fashion through the formation of multiple bonds.