Palladium-catalyzed Aryl Meta-C-H Decarboxylative Difluoromethylation

In recent years,C-H activation reaction involving directing groups have been developed at a high speed.Many hot reviews on this topic have been published in various journals.The introduction of directing groups can activate C-H bonds more effectively and selectively.More and more people are interested in organic compounds containing difluoromethylene,due to the special properties of difluoromethylene.Preparation of difluoroalkylation products by C-H activation with directing groups attract some chemists'attention because they have more extraordinary meaning.This paper reports on a noval method for constructing Csp²-CF₂ bond.We have achieved palladium-catalyzed aryl meta-C-H decarboxylative difluoromethylation with nitrogen-containing directing group.In this reaction,palladium as a catalyst with peroxysulphate as an oxidant and acetic acid as an additive.Aryl difluoroacetic acid was used as a source of difluoromethyl radicals.Aryl meta-C-H decarboxylative difluoromethylation was realized for the first time.Through the exploration of the reaction,we obtained aryl meta-C-H decarboxylative difluoromethylation.The structre of these products were identified by ¹H NMR,¹⁹F NMR,¹³C NMR,and X-ray.This method provides a new idea for meta-difluoroalkylation.