Construction Of C-C Bonds Via Copper(?)-Catalyzed C-H Functionalization And Decarboxylative Cross-Coupling Reactions

Transition-metal-catalyzed C-H functionalizations and decarboxylative cross-coupling reactions are important research fields in modern organic synthesis for the construction of carbon-carbon and carbon-heteroatom bonds.Despite a lot of relative literatures were reported,the development of efficient methods is still attractive.Copper salts,which are inexpensive,readily available and possess low toxicity,have been widely used in C-H functionalization and decarboxylative cross-coupling reactions for the construction of carbon-carbon bonds.In this study,the research content is concerned as following.First,multisubstituted furans represent an important class of five membered heterocycles ubiquitous in many natural products and pharmaceuticals.In this paper,eighteen multisubstituted furans were synthesized using BPO as the oxidant and Cu(?)as the catalyst under ligand-and additive-free conditions.The C(sp3)-H bond of arylmethyl ketones were activated to afford a radical intermediate catalyzed by copper.Subsequently,C-C bond was formed via the addition of radical intermediate to alkynoate.Then,C-0 bond was formed via cyclization to afford the heterocycle product.This protocol is characterized by mild conditions,high yields and wide substrate scope.Gram-scale application of the present method was also explored.The proposed reaction was investigated under the standard conditions without significant loss of reactive efficiency.Thus,this simple,efficient,and practical protocol has good prospects for industrialization.Second,transition-metal-catalyzed decarboxylative cross-coupling reactions of?,?-unsaturated carboxylic acids have attracted much attention,since it opens a new avenue for formation of carbon-carbon and carbon-heteroatom bonds.In this paper,thirteen styrene derivatives were synthesized in the present of oxidant and copper salts using cinnamic acids and aliphatic aldehyde as the raw materials.An alkyl radical can be generated from aliphatic aldehyde under oxidant and copper salts.Subsequently,C-C bond was formed via the addition of alkyl radical to cinnamic acids accompanied by decarboxylation.This protocol is characterized by mild conditions,wide substrate scope and simple posttreatment procedure.This transformation tolerated a wide range of functional groups.The ?,?-unsaturated acids with electron-rich substituents or electron-poor substituents both gave the desired products in moderate to good yields.