Cascade In Situ Iodination and Elemental Copper-Mediated Reductive Coupling for the Synthesis of 3-Difluoroacetate-Functionalized Chromones

Reported in this paper is an I2/Cu-mediated method for the synthesis of 3-difluoroacetate-functionalized chromones via cascade reactions between o-hydroxyaryl enaminones and alkyl difluoroacetates. The product construction involves a key in situ iodination generating 3-iodochromones, which enables the subsequent Cu(0)-mediated reductive coupling to provide the titled products under relatively mild conditions with a short reaction time without using any noble metal reagent.