Substituted 4H-1-benzopyran-4-ones (chromones): synthesis via palladium-catalysed coupling of their halogeno derivatives with alkenes

Abstract

Activation of bromochromones has been achieved by Pd⁰ insertion into the carbon–halogen bond. The resultant species undergo coupling with alkenes leading to vinylated chromones. Vinylation occurs regiospecifically at the original site of bromination and therefore provides a method for the clean introduction of substituents into the chromone ring system. An anomalous reaction of a dibrominated chromone leading to a ring-opened product is described.