An efficient and sustainable protocol for regioselective hydrocarboxylation of alkynes to construct diverse propionic acid derivatives is disclosed.Under photoinduced conditions,the anti-Markovnikov hydrocarboxylation...An efficient and sustainable protocol for regioselective hydrocarboxylation of alkynes to construct diverse propionic acid derivatives is disclosed.Under photoinduced conditions,the anti-Markovnikov hydrocarboxylation of alkynes was realized with CO_(2) radical anion in-situ generated from formate as both a carbonyl source and a reductant.The collaboration between photosensitizer and hydrogen atom transfer catalyst promoted the catalytic cycle to work smoothly,giving a broad substrate scope including terminal and internal alkynes.The Giese radical addition of CO_(2) radical anion to the C—C triple bond is the key step to initiate the reaction.展开更多
The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐...The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐unsaturated carboxylic acids.Both symmetrical and unsymmetrical monoalkynes show good reactivity.Importantly,2,2’‐(1,4‐phenylene)diacrylic acid can also be synthesized in high yield through the dihydrocarboxylation of 1,4‐diethynylbenzene.Besides,an excellent result in gram scale experiment and TON up to 900 can be obtained,displaying the efficiency of this protocol.Notably,regulating the types and concentrations of dehydrant can control the CO generation,avoiding directly operating toxic CO and circumventing sensitivity issue to the CO amount.On the basis of the attractive features of formic acid including easy preparation through CO_(2) hydrogenation and efficient liberation of CO,this protocol using formic acid as bridging reagent between CO_(2) and CO can be perceived as an indirect utilization of CO_(2),offering an alternative method for preparing acrylic acid analogues.展开更多
A multifunctional porous organic polymer of POP-Nixantphos-PPh_(3)-PhSO_(3)Na was prepared by free radical tricopolymerization.Further loading of Pd(OAc)2 led to the catalyst of Pd/POP-Nixantphos-PPh_(3)-PhSO_(3)Na.In...A multifunctional porous organic polymer of POP-Nixantphos-PPh_(3)-PhSO_(3)Na was prepared by free radical tricopolymerization.Further loading of Pd(OAc)2 led to the catalyst of Pd/POP-Nixantphos-PPh_(3)-PhSO_(3)Na.In this catalyst,Nixantphos ligand moieties were employed to enhance the catalytic hydrocarboxylation activity of palladium.Additionally,PPh_(3)ligand moieties were utilized to construct a porous framework of catalyst that facilitated the dispersion of Pd nanoparticles as well as the diffusion of reactants and products.Furthermore,the incorporation of PhSO_(3)Na moieties improved the hydrophilicity of the support.With H_(2)O as the reaction solvent,under the initial CO pressure of 0.1 MPa,Pd/POP-Nixantphos-PPh3-PhSO3Na-catalyzed hydrocarboxylation of alkynes to afford the correspondingα,β-unsaturated carboxylic acids in good yields(76%~96%).Various alkynes,such as diaromatic alkynes,arylalkyl alkynes and dialkyl alkynes,worked well in the process.Additionally,the catalyst showed excellent recyclability with no significant yield loss over five cycles.展开更多
文摘An efficient and sustainable protocol for regioselective hydrocarboxylation of alkynes to construct diverse propionic acid derivatives is disclosed.Under photoinduced conditions,the anti-Markovnikov hydrocarboxylation of alkynes was realized with CO_(2) radical anion in-situ generated from formate as both a carbonyl source and a reductant.The collaboration between photosensitizer and hydrogen atom transfer catalyst promoted the catalytic cycle to work smoothly,giving a broad substrate scope including terminal and internal alkynes.The Giese radical addition of CO_(2) radical anion to the C—C triple bond is the key step to initiate the reaction.
文摘The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐unsaturated carboxylic acids.Both symmetrical and unsymmetrical monoalkynes show good reactivity.Importantly,2,2’‐(1,4‐phenylene)diacrylic acid can also be synthesized in high yield through the dihydrocarboxylation of 1,4‐diethynylbenzene.Besides,an excellent result in gram scale experiment and TON up to 900 can be obtained,displaying the efficiency of this protocol.Notably,regulating the types and concentrations of dehydrant can control the CO generation,avoiding directly operating toxic CO and circumventing sensitivity issue to the CO amount.On the basis of the attractive features of formic acid including easy preparation through CO_(2) hydrogenation and efficient liberation of CO,this protocol using formic acid as bridging reagent between CO_(2) and CO can be perceived as an indirect utilization of CO_(2),offering an alternative method for preparing acrylic acid analogues.
文摘A multifunctional porous organic polymer of POP-Nixantphos-PPh_(3)-PhSO_(3)Na was prepared by free radical tricopolymerization.Further loading of Pd(OAc)2 led to the catalyst of Pd/POP-Nixantphos-PPh_(3)-PhSO_(3)Na.In this catalyst,Nixantphos ligand moieties were employed to enhance the catalytic hydrocarboxylation activity of palladium.Additionally,PPh_(3)ligand moieties were utilized to construct a porous framework of catalyst that facilitated the dispersion of Pd nanoparticles as well as the diffusion of reactants and products.Furthermore,the incorporation of PhSO_(3)Na moieties improved the hydrophilicity of the support.With H_(2)O as the reaction solvent,under the initial CO pressure of 0.1 MPa,Pd/POP-Nixantphos-PPh3-PhSO3Na-catalyzed hydrocarboxylation of alkynes to afford the correspondingα,β-unsaturated carboxylic acids in good yields(76%~96%).Various alkynes,such as diaromatic alkynes,arylalkyl alkynes and dialkyl alkynes,worked well in the process.Additionally,the catalyst showed excellent recyclability with no significant yield loss over five cycles.
