金属钯催化偶联反应在现代有机合成中起着至关重要的作用。为了对其机理进行详细探索,以目前在药物合成和化工生产中非常热门的吲哚与芳基硼酸偶联反应作为研究对象,选取三氟乙酸钯作为催化剂,采用密度泛函理论(density functional theo...金属钯催化偶联反应在现代有机合成中起着至关重要的作用。为了对其机理进行详细探索,以目前在药物合成和化工生产中非常热门的吲哚与芳基硼酸偶联反应作为研究对象,选取三氟乙酸钯作为催化剂,采用密度泛函理论(density functional theory,DFT)中的贝克三重杂化泛函及李-杨-帕尔的局部密度近似(Baker′s triple hybrid functional and Li-Yang-Parr′s local density approximation,B3LYP)方法,通过计算,对钯催化无外加配体的吲哚与芳基硼酸偶联反应提出如下反应机理:第一步,三氟乙酸钯与芳基硼酸反应生成芳基钯中间体;第二步,芳基钯中间体作为亲电试剂进攻吲哚的C-3位;第三步,芳基钯从吲哚的C-3位迁移到C-2位;第四步,三氟乙酸的配位三氟乙酸根开环夺走吲哚上的氢质子;第五步,金属钯还原消除,并在空气作用下被氧化为三氟乙酸钯,催化剂被复原。该研究可拓展至其他芳基配体,为合成复杂分子提供新方法。展开更多
Polyphenylene dendrimers 11,12 and 13 containing terminal trimethylsilyl groups have been synthesized by phosphine-free palladium chloride catalyzed Suzuki couplings of 1,3,5-tris(3′,5′-dibromophenyl)benzene 9 with ...Polyphenylene dendrimers 11,12 and 13 containing terminal trimethylsilyl groups have been synthesized by phosphine-free palladium chloride catalyzed Suzuki couplings of 1,3,5-tris(3′,5′-dibromophenyl)benzene 9 with aryl boronic acids 5 and 6.These macromolecules were characterized by Fourier transform infrared (FTIR),nuclear magnetic resonance (NMR) and matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectra.Gel permeation chromatograph (GPC) indicated that the hydrodynamic radium of 12,with trimethylsiliyl (—TMS) groups substituted at para-positions on its terminal benzene rings,was larger than that of 13,with trimethylsiliyl groups substituted at meta-positions on its terminal benzene rings.X-ray powder diffraction patterns showed that dendrimer 12 was of a certain amount of crystallinity and dendrimer 13 was amorphous.展开更多
A Cu2O/SiC heterogeneous catalyst was prepared via a two‐step liquid‐phase method using diethyleneglycol as both the solvent and the reducing agent.The catalyst was characterized using X‐raydiffraction,X‐ray photo...A Cu2O/SiC heterogeneous catalyst was prepared via a two‐step liquid‐phase method using diethyleneglycol as both the solvent and the reducing agent.The catalyst was characterized using X‐raydiffraction,X‐ray photoelectron spectroscopy,scanning electron microscopy(SEM),transmissionelectron microscopy(TEM),and H2temperature‐programmed reduction.All the results indicatethat Cu is present on the SiC support primarily as Cu2O.The SEM and TEM results show that cubicCu2O nanoparticles are uniformly dispersed on theβ‐SiC surface.The reaction conditions,namelythe temperature,reaction time,and amounts of base and catalyst used,for the Ullmann‐type C–Ocross‐coupling reaction were optimized.A model reaction was performed using iodobenzene(14.0mmol)and phenol(14.0mmol)with Cu2O/SiC(5wt%Cu)as the catalyst,Cs2CO3(1.0equiv.)as thebase,and tetrahydrofuran as the solvent at150°C for3h;a yield of97%was obtained and theturnover frequency(TOF)was1136h?1.The Cu2O/SiC catalyst has a broad substrate scope and canbe used in Ullmann‐type C–O cross‐coupling reactions of aryl halides and phenols bearing a varietyof different substituents.The catalyst also showed high activity in the Ullmann‐type C–Scross‐coupling of thiophenol with iodobenzene and substituted iodobenzenes;a TOF of1186h?1was achieved.The recyclability of the Cu2O/SiC catalyst in the O‐arylation of phenol with iodobenzenewas investigated under the optimum conditions.The yield decreased from97%to64%afterfive cycles.The main reason for the decrease in the catalyst activity is loss of the active component,i.e.,Cu2O.展开更多
Umpolung reactions of C=X bonds(X=O,N)are valuable ways of constructing new C–C bonds,which are sometimes difficult to be constructed using traditional synthetic pathways.Classical polarity inversion of C=X bonds(X=O...Umpolung reactions of C=X bonds(X=O,N)are valuable ways of constructing new C–C bonds,which are sometimes difficult to be constructed using traditional synthetic pathways.Classical polarity inversion of C=X bonds(X=O,N)usually requires air or moisture‐sensitive and strong reducing agents,which limit the feasibility of substrate scope.Herein we describe a photo‐induced reductive cross‐coupling reaction of aldehydes,ketones and imines with electron‐deficient arenes(aromatic nitriles)using fac‐Ir(ppy)3as a photocatalyst and diisopropylethylamine(DIPEA)as a terminal reductant under visible light irradiation.Mild conditions and high yields mean that this new polarity inversion strategy can be used with aryl‐substituted alcohols and amines.Spectroscopic studies and control experiments have demonstrated the oxidative quenching of Ir(ppy)3*by electron‐deficient arenes involved in the key step for the C–C bond formation.展开更多
CuCl/Phen can catalyze the C–N coupling between arylboronic acid and benzofurazan1‐oxide.This reaction occurred under mild and redox‐neutral conditions with benzofurazan1‐oxide as an aminating reagent via ring sci...CuCl/Phen can catalyze the C–N coupling between arylboronic acid and benzofurazan1‐oxide.This reaction occurred under mild and redox‐neutral conditions with benzofurazan1‐oxide as an aminating reagent via ring scission,leading to a bifunctionalized aminonitrobenzene.展开更多
Highly efficient cross-couplings of diarylborinic acids with aryl tosylates and sulfamates are reported for construction of biaryls using a tri(4-methoxyphenyl)phosphine-supported nickel catalyst system: Ni[P(4-MeOC6H...Highly efficient cross-couplings of diarylborinic acids with aryl tosylates and sulfamates are reported for construction of biaryls using a tri(4-methoxyphenyl)phosphine-supported nickel catalyst system: Ni[P(4-MeOC6H4)3]2Cl2/2P(4-MeOC6H4)3 in the presence of K3PO4·3H2O in toluene. A variety of unsymmetrical biaryls could be obtained in good to excellent yields with1.5–3 mol% or 3–5 mol% catalyst loadings for aryl sulfamates and tosylates, respectively. In sharp contrast to the conventional nickel-catalyzed Suzuki coupling with arylboronic acids, arylsulfamates unexpectedly displayed a higher reactivity than the corresponding tosylates in coupling with diarylborinic acids catalyzed by the nickel/phosphine catalyst system.展开更多
A merger of copper catalysis and semiconductor photocatalysis using polymeric carbon nitride(PCN)for multi-type cross-coupling reactions was developed.This dual-catalytic system enables mild C-H arylation,chalcogenati...A merger of copper catalysis and semiconductor photocatalysis using polymeric carbon nitride(PCN)for multi-type cross-coupling reactions was developed.This dual-catalytic system enables mild C-H arylation,chalcogenation,and C-N cross-coupling reactions under visible light irradiation with a broad substrate scope.Good-to-excellent yields were obtained with appreciable site selectivity and functional group tolerance.Metal-free and low-cost PCN photocatalyst can easily be recovered and reused several times.展开更多
Palladium nanoparticles immobilized on a cross-linked imidazolium-containing polymer were evaluated as a catalyst for Suzuki carbon-carbon cross-coupling reactions using water as the solvent. The nanocatalysts show go...Palladium nanoparticles immobilized on a cross-linked imidazolium-containing polymer were evaluated as a catalyst for Suzuki carbon-carbon cross-coupling reactions using water as the solvent. The nanocatalysts show good catalytic activities for aryl iodides and aryl bromides and moderate activity with aryl chloride substrates. Coupling of sterically hindered substrates could also be achieved in reasonable yields. The heterogeneous catalyst is stable, can be stored without precautions to exclude air or moisture, and can be easily recycled and reused.展开更多
文摘金属钯催化偶联反应在现代有机合成中起着至关重要的作用。为了对其机理进行详细探索,以目前在药物合成和化工生产中非常热门的吲哚与芳基硼酸偶联反应作为研究对象,选取三氟乙酸钯作为催化剂,采用密度泛函理论(density functional theory,DFT)中的贝克三重杂化泛函及李-杨-帕尔的局部密度近似(Baker′s triple hybrid functional and Li-Yang-Parr′s local density approximation,B3LYP)方法,通过计算,对钯催化无外加配体的吲哚与芳基硼酸偶联反应提出如下反应机理:第一步,三氟乙酸钯与芳基硼酸反应生成芳基钯中间体;第二步,芳基钯中间体作为亲电试剂进攻吲哚的C-3位;第三步,芳基钯从吲哚的C-3位迁移到C-2位;第四步,三氟乙酸的配位三氟乙酸根开环夺走吲哚上的氢质子;第五步,金属钯还原消除,并在空气作用下被氧化为三氟乙酸钯,催化剂被复原。该研究可拓展至其他芳基配体,为合成复杂分子提供新方法。
文摘Polyphenylene dendrimers 11,12 and 13 containing terminal trimethylsilyl groups have been synthesized by phosphine-free palladium chloride catalyzed Suzuki couplings of 1,3,5-tris(3′,5′-dibromophenyl)benzene 9 with aryl boronic acids 5 and 6.These macromolecules were characterized by Fourier transform infrared (FTIR),nuclear magnetic resonance (NMR) and matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectra.Gel permeation chromatograph (GPC) indicated that the hydrodynamic radium of 12,with trimethylsiliyl (—TMS) groups substituted at para-positions on its terminal benzene rings,was larger than that of 13,with trimethylsiliyl groups substituted at meta-positions on its terminal benzene rings.X-ray powder diffraction patterns showed that dendrimer 12 was of a certain amount of crystallinity and dendrimer 13 was amorphous.
基金supported by the National Natural Science Foundation of China (21203233,21473232,21403270)Youth Innovation Promotion Association,CAS (2013115)~~
文摘A Cu2O/SiC heterogeneous catalyst was prepared via a two‐step liquid‐phase method using diethyleneglycol as both the solvent and the reducing agent.The catalyst was characterized using X‐raydiffraction,X‐ray photoelectron spectroscopy,scanning electron microscopy(SEM),transmissionelectron microscopy(TEM),and H2temperature‐programmed reduction.All the results indicatethat Cu is present on the SiC support primarily as Cu2O.The SEM and TEM results show that cubicCu2O nanoparticles are uniformly dispersed on theβ‐SiC surface.The reaction conditions,namelythe temperature,reaction time,and amounts of base and catalyst used,for the Ullmann‐type C–Ocross‐coupling reaction were optimized.A model reaction was performed using iodobenzene(14.0mmol)and phenol(14.0mmol)with Cu2O/SiC(5wt%Cu)as the catalyst,Cs2CO3(1.0equiv.)as thebase,and tetrahydrofuran as the solvent at150°C for3h;a yield of97%was obtained and theturnover frequency(TOF)was1136h?1.The Cu2O/SiC catalyst has a broad substrate scope and canbe used in Ullmann‐type C–O cross‐coupling reactions of aryl halides and phenols bearing a varietyof different substituents.The catalyst also showed high activity in the Ullmann‐type C–Scross‐coupling of thiophenol with iodobenzene and substituted iodobenzenes;a TOF of1186h?1was achieved.The recyclability of the Cu2O/SiC catalyst in the O‐arylation of phenol with iodobenzenewas investigated under the optimum conditions.The yield decreased from97%to64%afterfive cycles.The main reason for the decrease in the catalyst activity is loss of the active component,i.e.,Cu2O.
文摘Umpolung reactions of C=X bonds(X=O,N)are valuable ways of constructing new C–C bonds,which are sometimes difficult to be constructed using traditional synthetic pathways.Classical polarity inversion of C=X bonds(X=O,N)usually requires air or moisture‐sensitive and strong reducing agents,which limit the feasibility of substrate scope.Herein we describe a photo‐induced reductive cross‐coupling reaction of aldehydes,ketones and imines with electron‐deficient arenes(aromatic nitriles)using fac‐Ir(ppy)3as a photocatalyst and diisopropylethylamine(DIPEA)as a terminal reductant under visible light irradiation.Mild conditions and high yields mean that this new polarity inversion strategy can be used with aryl‐substituted alcohols and amines.Spectroscopic studies and control experiments have demonstrated the oxidative quenching of Ir(ppy)3*by electron‐deficient arenes involved in the key step for the C–C bond formation.
基金supported by the National Natural Science Foundation of China(21525208 and 21472186)Research Fund from Henan Normal University(5101034011009)~~
文摘CuCl/Phen can catalyze the C–N coupling between arylboronic acid and benzofurazan1‐oxide.This reaction occurred under mild and redox‐neutral conditions with benzofurazan1‐oxide as an aminating reagent via ring scission,leading to a bifunctionalized aminonitrobenzene.
基金This work was supported by the National Natural Science Foundation of China(20972049).
文摘Highly efficient cross-couplings of diarylborinic acids with aryl tosylates and sulfamates are reported for construction of biaryls using a tri(4-methoxyphenyl)phosphine-supported nickel catalyst system: Ni[P(4-MeOC6H4)3]2Cl2/2P(4-MeOC6H4)3 in the presence of K3PO4·3H2O in toluene. A variety of unsymmetrical biaryls could be obtained in good to excellent yields with1.5–3 mol% or 3–5 mol% catalyst loadings for aryl sulfamates and tosylates, respectively. In sharp contrast to the conventional nickel-catalyzed Suzuki coupling with arylboronic acids, arylsulfamates unexpectedly displayed a higher reactivity than the corresponding tosylates in coupling with diarylborinic acids catalyzed by the nickel/phosphine catalyst system.
基金supported by the National Natural Science Foundation of China(21972094 and 21805191)Guangdong Special Support Program+4 种基金Pengcheng Scholar ProgramChina Postdoctoral Science Foundation(2019M653004)Shenzhen Peacock Plan(KQTD2016053112042971)Shenzhen Science and Technology Program(JCYJ20190808142001745,JCYJ20200812160737002,and RCJC20200714114434086)Guangdong Basic and Applied Basic Research Foundation(2020A1515010982)。
文摘A merger of copper catalysis and semiconductor photocatalysis using polymeric carbon nitride(PCN)for multi-type cross-coupling reactions was developed.This dual-catalytic system enables mild C-H arylation,chalcogenation,and C-N cross-coupling reactions under visible light irradiation with a broad substrate scope.Good-to-excellent yields were obtained with appreciable site selectivity and functional group tolerance.Metal-free and low-cost PCN photocatalyst can easily be recovered and reused several times.
基金supported by the Ecole Polytechnique Fédérale de Lausanne and the Iranian Ministry of Science,Research and Technology(to S.G.-E.)
文摘Palladium nanoparticles immobilized on a cross-linked imidazolium-containing polymer were evaluated as a catalyst for Suzuki carbon-carbon cross-coupling reactions using water as the solvent. The nanocatalysts show good catalytic activities for aryl iodides and aryl bromides and moderate activity with aryl chloride substrates. Coupling of sterically hindered substrates could also be achieved in reasonable yields. The heterogeneous catalyst is stable, can be stored without precautions to exclude air or moisture, and can be easily recycled and reused.
