Transition-metal catalyzed cross-coupling is one of the basic strategies for the C-C bond formation.However,it is difficult to achieve satisfactory results when terminal alkynes with electron-withdrawing group such as...Transition-metal catalyzed cross-coupling is one of the basic strategies for the C-C bond formation.However,it is difficult to achieve satisfactory results when terminal alkynes with electron-withdrawing group such as propiolate esters are used.The reason behind this might be the easy polymerization of this type of alkynes in the presence of base.A tetrahydroxydiboron and copper sulfate co-promoted cross-coupling/cyclization of propiolate esters and o-iodobenzoic acid for the facile and efficient construction of phthalides is described.Preliminary mechanism study indicates that tetrahydroxydiboron can inhibit the polymerization of propiolate esters and increase the reaction rate.This method is characterized by high regio-and stereoselectivities,mild reaction conditions,short reaction time,broad substrate scope,and excellent functional group compatibility.展开更多
An efficient and facile method for the synthesis of 3-indolyl-substituted phthalides by Friedel-Crafts alkylation of indoles with 3-hydroxyisobenzofuran-1(3H)-one has been developed. Using only 2 mol-% TsOH·H2O a...An efficient and facile method for the synthesis of 3-indolyl-substituted phthalides by Friedel-Crafts alkylation of indoles with 3-hydroxyisobenzofuran-1(3H)-one has been developed. Using only 2 mol-% TsOH·H2O as the catalyst, various substituted indoles can react smoothly at room temperature to give the corresponding phthalides products in good to excellent yields (up to 96%).展开更多
Phthalides represent an important class of bioactive heterocycle extensively found in pharmaceuticals and natural products,their syntheses have attracted extensively attention.A water-promoted and rhodium-catalyzed[3+...Phthalides represent an important class of bioactive heterocycle extensively found in pharmaceuticals and natural products,their syntheses have attracted extensively attention.A water-promoted and rhodium-catalyzed[3+2]tandem cyclization of aromatic acids and acrylates has been developed in air and neat water free of any additives,which provides an environmentally benign approach for constructing phthalide motifs.Compared with previous literatures,this methodology features quite simple reaction conditions,simple operation and additive-free.Mechanistic studies indicate that apart from the many other well-known oxidations of Rh(I)by external oxidant,hydrogen transfer with the acrylate being a hydrogen acceptor is involved to regenerate the active Rh species,which is different from documented metal-catalyzed phthalides syntheses.The application of this protocol is further demonstrated by the green synthesis of biologically active isoochracinic acid in one step.展开更多
文摘Transition-metal catalyzed cross-coupling is one of the basic strategies for the C-C bond formation.However,it is difficult to achieve satisfactory results when terminal alkynes with electron-withdrawing group such as propiolate esters are used.The reason behind this might be the easy polymerization of this type of alkynes in the presence of base.A tetrahydroxydiboron and copper sulfate co-promoted cross-coupling/cyclization of propiolate esters and o-iodobenzoic acid for the facile and efficient construction of phthalides is described.Preliminary mechanism study indicates that tetrahydroxydiboron can inhibit the polymerization of propiolate esters and increase the reaction rate.This method is characterized by high regio-and stereoselectivities,mild reaction conditions,short reaction time,broad substrate scope,and excellent functional group compatibility.
文摘An efficient and facile method for the synthesis of 3-indolyl-substituted phthalides by Friedel-Crafts alkylation of indoles with 3-hydroxyisobenzofuran-1(3H)-one has been developed. Using only 2 mol-% TsOH·H2O as the catalyst, various substituted indoles can react smoothly at room temperature to give the corresponding phthalides products in good to excellent yields (up to 96%).
文摘Phthalides represent an important class of bioactive heterocycle extensively found in pharmaceuticals and natural products,their syntheses have attracted extensively attention.A water-promoted and rhodium-catalyzed[3+2]tandem cyclization of aromatic acids and acrylates has been developed in air and neat water free of any additives,which provides an environmentally benign approach for constructing phthalide motifs.Compared with previous literatures,this methodology features quite simple reaction conditions,simple operation and additive-free.Mechanistic studies indicate that apart from the many other well-known oxidations of Rh(I)by external oxidant,hydrogen transfer with the acrylate being a hydrogen acceptor is involved to regenerate the active Rh species,which is different from documented metal-catalyzed phthalides syntheses.The application of this protocol is further demonstrated by the green synthesis of biologically active isoochracinic acid in one step.
