Palladium-catalysed cyclocarbonylative Sonogashira annulation toward flavones using Mn2(CO)10 as a carbonyl source at room temperature.

A facile palladium-catalysed cyclocarbonylative Sonogashira cascade reaction for flavone synthesis is disclosed herein. By utilizing Mn2(CO)10 as a solid carbonyl surrogate, this protocol completely circumvents the safety risks of high-pressure CO gas. The transformation operates efficiently at room temperature with low palladium loading and tolerates a wide range of functional groups as well as aromatic, heteroaromatic and aliphatic alkynes. The reaction proceeds via successive C-C and C-O bond formation. The methodology is readily scalable to the gram scale and enables late-stage derivatization of flavone scaffolds. This mild, safe and sustainable approach offers a powerful synthetic tool for constructing diverse flavone derivatives and related bioactive compounds.