C(sp)–C(sp³) Bond Formation through Ligand- and Additive-Free CuO-Mediated Decarboxylative Direct Cross-Coupling of Coumarin-/Chromone-3-carboxylic Acids and Terminal Alkynes

A practical and efficient method for the synthesis of functionalized 4-(aryl-/heteroaryl-ethynyl)chroman-2-ones and 2-(aryl-/heteroaryl-ethynyl)chroman-4-ones through copper-catalyzed decarboxylative direct cross-coupling of coumarin-/chromone-3-carboxylic acids with terminal alkynes, leading to the formation of C(sp)–C(sp3) bonds, has been unearthed. Advantages of this protocol include avoidance of any ligands and bases, a broad substrate scope, tolerance of diverse functional groups, and good to excellent yields.