Silver-Catalyzed/Visible Light Catalyzed Decarboxylative Free Radical Reaction Of Aryl Propynoic Acid

Transition metal-catalyzed decarboxylation has become a very important strategy in organic synthesis.Silver-catalyzed decarboxylation is widely used in Hunsdiecker halogenation reaction,carbon-carbon bond formation,carbon-hetero bond formation,C-H bond functionalization and so on.Silver-catalyzed decarboxylation can initiate selective decarboxylative coupling via free radical process with the assistance of persulfate or other oxidants.The reaction has the characteristics of simple operation,no need to exclude or water air,mild reaction conditions and so on.It is a controllable free radical reaction.Ynones are privileged building blocks in various organic syntheses of heterocyclic derivatives due to their multifunctional nature,and flavones are an important class of natural products with a wide range of biological activities.We describe the catalytic double decarboxylative alkynylation of arylpropiolic acids with ?-keto acids.With Ag(I)/persulfate as the catalysis system,the valuable ynones bearing various substituents could be easily obtained.The introduction of hydroxyl substituent on ortho-site of ?-keto acids make this strategy further applicable to the construction of flavone derivatives via heteroannulation in moderate to good yields with a similar silver-catalyzed system.The reactions proceed under relatively mild reaction conditions and tolerate a wide variety of functional groups.Control experiments indicated that both the reactions undergo radical processes.Carboxylic acid and its derivatives are abundant and cheap organic and biological molecules,so it is an important goal to convert carboxylic acid into high-value products.In recent years,visible light catalyzed decarboxylative coupling reaction has become an important chemical conversion because of its wide range of substrates,mild reaction conditions,high efficiency and applicality.In this paper,we describe the photocatalytic decarboxylation of aryl propionic acid and aryl diazonium salts/sodium trifluoromethylsulfinate to produce substituted diaryl diketone derivatives or trifluoromethyl products in varying yields.The reaction was carried out under relatively mild conditions and the functional groups were well tolerated.