Substituted 4H-1-benzopyran-4-ones (chromones): synthesis via palladium-catalysed coupling of their halogeno derivatives with alkenes
作者:Stephen G. Davies、Bryan E. Mobbs、Christopher J. Goodwin
DOI:10.1039/p19870002597
日期:——
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.
Although phenols react with dimethylacetylenedicarboxylate (DMAD) to give a mixture of both cis- and trans-addition products, the reaction with DMAD adsorbed on alumina gives cis-addition products stereoselectively.