A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition m...A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K<sub>3</sub>PO<sub>4</sub>) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .展开更多
The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-...The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-C bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo_(2)C catalyst.The catalytic activity on Ni doped Mo_(2)C with TOF of 6.9×10^(3)h^(-1)is much superior to intrinsic Mo_(2)C catalyst,which is also higher than most noble metal catalysts.Structurally,the doped Ni raises the active particle dispersion and the coordination numbers of Mo species(Mo-C and Mo-O),improves the graphitization degree to promote the electron transfer,and increases the amount of Lewis and Br?nsted acid,which are responsible for the excellent hydrodeoxygenation performance.The Ni promotes simultaneously C-O and C-C bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping.These findings contribute to the understanding of the nature of Ni-doped Mo_(2)C on the roles as catalytic active sites for C-O and C-C bonds cleavage.展开更多
A simple protocol for reductive cleavage of C--O bond in diaryl and aryl methyl ethers was reported, in which Nail served as a reducing agent and KO Bu as a base and a radical initiator. The combination of Nail and KO...A simple protocol for reductive cleavage of C--O bond in diaryl and aryl methyl ethers was reported, in which Nail served as a reducing agent and KO Bu as a base and a radical initiator. The combination of Nail and KOBu displayed high efficiency for reductive cleavage of C-O bond in diaryl and awl ethers （e.g., dibenzofuran, diphe- nyl ether, anisole） without the hydrogenation of the aryl rings, in the absence of any other catalysts or ligands at 140 ℃, producing corresponding arenes and phenols. It was indicated that the reaction was under a radical mecha- nism.展开更多
The reductive cross-coupling between C(aryl)—O and Si—Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)—Si bonds but has remained a great challenge.Herein,we report a reductive c...The reductive cross-coupling between C(aryl)—O and Si—Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)—Si bonds but has remained a great challenge.Herein,we report a reductive cross-coupling of diaryl ethers and chlorosilanes via strong electrophilic C(aryl)—O and Si—Cl bonds cleavage by iron catalysis,which constitutes an efficient protocol for the synthesis of a range of functionalized arylsilanes.The combination of low cost FeCl2 as the precatalyst and iPrMgCl as the reductant shows high activity in the successive cleavage of unactivated C(aryl)—O bonds of diaryl ethers and strong electrophilic Si—Cl bonds of chlorosilanes,allowing their cross-coupling in a reductive fashion.The low-valent iron species generated in situ by reduction of FeCl2 with iPrMgCl was proposed,which prefers to initially cleavage the C(aryl)—O bond of diaryl ethers with the chelation help of an o-amide auxiliary.展开更多
While supported-noble-metal catalysts have been widely investigated in hydrotreating reactions,a crucial issue that the catalytic system is still confronted with is developing an efficient approach to gain the high di...While supported-noble-metal catalysts have been widely investigated in hydrotreating reactions,a crucial issue that the catalytic system is still confronted with is developing an efficient approach to gain the high dispersion of noble metals under reducing conditions.In this work,Ru was supported on two MnOx with different specific surface areas(SSAs),and a much higher dispersion of Ru(83%,in contrast to 42%of the other one)was surprisingly observed over MnO with much lower SSA(around one-third of the other one).A suite of complementary characterizations demonstrates that,compared with the catalyst with high SSA(Ru/MnO-H),the MnO in the one with lower SSA(Ru/MnO-L)contains enriched surface oxygen that creates more abundant sites and bears stronger strength to anchor Ru species,mitigating the aggregation of Ru under reducing condition.This not only enriched active sites(i.e.,exposed Ru),but also created a more electron-deficient Ru domain and thus enhanced the redox property of the surface,leading to the lower barrier for C–O bond hydrogenolysis.In the hydrogenolysis of diphenyl ether,Ru/MnO-L exhibited significantly enhanced activity(i.e.,6 folds of Ru/MnO-H)and high stability.This work provides an approach to regulate the surface chemistry of support for the high dispersion of supported metal.展开更多
A nickel-catalysed reduction of phenol derivatives activated by 2,4,6-trichloro-1,3,5-triazine (TCT) in ecofriendly 2-methyltetrahydrofuran (2-MeTHF) is described. The phenol-TCT derivatives were readily prepared usin...A nickel-catalysed reduction of phenol derivatives activated by 2,4,6-trichloro-1,3,5-triazine (TCT) in ecofriendly 2-methyltetrahydrofuran (2-MeTHF) is described. The phenol-TCT derivatives were readily prepared using grinding method in short time without further purification. This catalytic system allowed the facile C-O cleavage of phenol-TCT derivatives under mild reaction conditions with high efficiency and good functional group tolerance. Gram-scale reaction was also achieved. Particularly, sequential functionalization of phenol-TCT derivatives followed by C-O bond reduction could also be realized,affording the high value-added products in moderate to good yields.展开更多
The shortage of resources and the destruction of the environment have caused serious resource and environmental problems shared by all countries around the world. As a ubiquitous renewable resource, biomass has great ...The shortage of resources and the destruction of the environment have caused serious resource and environmental problems shared by all countries around the world. As a ubiquitous renewable resource, biomass has great prospects for replacing fossil energy and attracted attention from the society. The use of catalytic approach to transform biomass into high-value chemicals is an effective way to use biomass efficiently. In this work, Nisupported catalysts has been developed for the selective cleavage of C–O bonds in lignin model compounds with 2-propanol as the hydrogen source solvent. Among these catalysts, it was indicated that zirconium phosphate(Zr P)-supported Ni catalysts were highly efficient and recyclable for alkyl-aryl ether(α-O-4 and β-O-4) cleavage in lignin model compounds. The further investigation demonstrated that the transfer hydrogenolysis of the C–O bond is highly selective, which afforded phenols and aromatics as dominant products without the products arising from hydrogenation of aromatic rings. Through a series of characterization of the catalyst, it was demonstrated that the medium strong acid sites of the Zr P support promoted the cleavage of alkyl-aryl ethers(α-O-4 and β-O-4),and Br?nsted acid sites favored for achieving high selectivity toward C–O bond cleavage. Additionally, Ni(0) sites on the Zr P catalysts were responsible for the catalytic transfer hydrogenolysis.展开更多
A copper-catalyzed three-component reaction of alkenes,cycloketone oximes and DABCO·(SO_(2))_(2) is de-veloped,which provides a convenient route for the synthesis of diverse(E)-cyanoalkylsulfonyl alkenes in moder...A copper-catalyzed three-component reaction of alkenes,cycloketone oximes and DABCO·(SO_(2))_(2) is de-veloped,which provides a convenient route for the synthesis of diverse(E)-cyanoalkylsulfonyl alkenes in moderate to good yields with excellent regio-and stereoselectivity.A broad substrate scope with ex-cellent functional group tolerance is observed.A plausible radical pathway is proposed,which involves copper-catalyzed ring-opening C–C bond cleavage of O-acyl oxime and insertion of sulfur dioxide.During the reaction process,cyanoalkyl radical and cyanoalkylsulfonyl radical are the key intermediates.展开更多
文摘A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K<sub>3</sub>PO<sub>4</sub>) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .
基金financially supported by the National Natural Science Foundation of China(21972099)the Application Foundation Program of Sichuan Province(2021YJ0305)+1 种基金the 111 project(B17030).Shanghai Synchrotron Radiation Facility(SSRF)for XAS experiments and the support by the project from NPL of CAEP(2019BB08)。
文摘The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-C bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo_(2)C catalyst.The catalytic activity on Ni doped Mo_(2)C with TOF of 6.9×10^(3)h^(-1)is much superior to intrinsic Mo_(2)C catalyst,which is also higher than most noble metal catalysts.Structurally,the doped Ni raises the active particle dispersion and the coordination numbers of Mo species(Mo-C and Mo-O),improves the graphitization degree to promote the electron transfer,and increases the amount of Lewis and Br?nsted acid,which are responsible for the excellent hydrodeoxygenation performance.The Ni promotes simultaneously C-O and C-C bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping.These findings contribute to the understanding of the nature of Ni-doped Mo_(2)C on the roles as catalytic active sites for C-O and C-C bonds cleavage.
文摘A simple protocol for reductive cleavage of C--O bond in diaryl and aryl methyl ethers was reported, in which Nail served as a reducing agent and KO Bu as a base and a radical initiator. The combination of Nail and KOBu displayed high efficiency for reductive cleavage of C-O bond in diaryl and awl ethers （e.g., dibenzofuran, diphe- nyl ether, anisole） without the hydrogenation of the aryl rings, in the absence of any other catalysts or ligands at 140 ℃, producing corresponding arenes and phenols. It was indicated that the reaction was under a radical mecha- nism.
基金financial support from the National Natural Science Foundation of China(21901206)Postdoctoral Science Foundation of China(2022M712589)+2 种基金General key R&D Projects in Shaanxi Province(2023-YBGY-321)Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX0826)Fundamental Research Funds for the Central Universities and the Haihe Laboratory of Sustainable Chemical Transformation.
文摘The reductive cross-coupling between C(aryl)—O and Si—Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)—Si bonds but has remained a great challenge.Herein,we report a reductive cross-coupling of diaryl ethers and chlorosilanes via strong electrophilic C(aryl)—O and Si—Cl bonds cleavage by iron catalysis,which constitutes an efficient protocol for the synthesis of a range of functionalized arylsilanes.The combination of low cost FeCl2 as the precatalyst and iPrMgCl as the reductant shows high activity in the successive cleavage of unactivated C(aryl)—O bonds of diaryl ethers and strong electrophilic Si—Cl bonds of chlorosilanes,allowing their cross-coupling in a reductive fashion.The low-valent iron species generated in situ by reduction of FeCl2 with iPrMgCl was proposed,which prefers to initially cleavage the C(aryl)—O bond of diaryl ethers with the chelation help of an o-amide auxiliary.
基金the National Natural Science Foundation of China(Nos.22025604,21976196,21936005,and 21878244)the fellowship of China Postdoctoral Science Foundation(No.2022M713308)the Special Project of Eco-environmental Technology for Emission Peak&Carbon Neutralization(No.RCEES-TDZ-2021-4).
文摘While supported-noble-metal catalysts have been widely investigated in hydrotreating reactions,a crucial issue that the catalytic system is still confronted with is developing an efficient approach to gain the high dispersion of noble metals under reducing conditions.In this work,Ru was supported on two MnOx with different specific surface areas(SSAs),and a much higher dispersion of Ru(83%,in contrast to 42%of the other one)was surprisingly observed over MnO with much lower SSA(around one-third of the other one).A suite of complementary characterizations demonstrates that,compared with the catalyst with high SSA(Ru/MnO-H),the MnO in the one with lower SSA(Ru/MnO-L)contains enriched surface oxygen that creates more abundant sites and bears stronger strength to anchor Ru species,mitigating the aggregation of Ru under reducing condition.This not only enriched active sites(i.e.,exposed Ru),but also created a more electron-deficient Ru domain and thus enhanced the redox property of the surface,leading to the lower barrier for C–O bond hydrogenolysis.In the hydrogenolysis of diphenyl ether,Ru/MnO-L exhibited significantly enhanced activity(i.e.,6 folds of Ru/MnO-H)and high stability.This work provides an approach to regulate the surface chemistry of support for the high dispersion of supported metal.
基金financial support from the National Natural Science Foundation of China(Nos. 21302014 and 21676030)the Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology (No. BM2012110)+2 种基金the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutionsthe Advanced Catalysis and Green Manufacturing Collaborative Innovation Center of Changzhou UniversityTopnotch Academic Programs Project of Jiangsu Higher Education Institutions (No. PPZY2015B145)
文摘A nickel-catalysed reduction of phenol derivatives activated by 2,4,6-trichloro-1,3,5-triazine (TCT) in ecofriendly 2-methyltetrahydrofuran (2-MeTHF) is described. The phenol-TCT derivatives were readily prepared using grinding method in short time without further purification. This catalytic system allowed the facile C-O cleavage of phenol-TCT derivatives under mild reaction conditions with high efficiency and good functional group tolerance. Gram-scale reaction was also achieved. Particularly, sequential functionalization of phenol-TCT derivatives followed by C-O bond reduction could also be realized,affording the high value-added products in moderate to good yields.
基金support from the National Natural Science Foundation of China(21773061,21978095)the Open Research Fund of Shanghai Key Laboratory of Green Chemistry and Chemical Processes。
文摘The shortage of resources and the destruction of the environment have caused serious resource and environmental problems shared by all countries around the world. As a ubiquitous renewable resource, biomass has great prospects for replacing fossil energy and attracted attention from the society. The use of catalytic approach to transform biomass into high-value chemicals is an effective way to use biomass efficiently. In this work, Nisupported catalysts has been developed for the selective cleavage of C–O bonds in lignin model compounds with 2-propanol as the hydrogen source solvent. Among these catalysts, it was indicated that zirconium phosphate(Zr P)-supported Ni catalysts were highly efficient and recyclable for alkyl-aryl ether(α-O-4 and β-O-4) cleavage in lignin model compounds. The further investigation demonstrated that the transfer hydrogenolysis of the C–O bond is highly selective, which afforded phenols and aromatics as dominant products without the products arising from hydrogenation of aromatic rings. Through a series of characterization of the catalyst, it was demonstrated that the medium strong acid sites of the Zr P support promoted the cleavage of alkyl-aryl ethers(α-O-4 and β-O-4),and Br?nsted acid sites favored for achieving high selectivity toward C–O bond cleavage. Additionally, Ni(0) sites on the Zr P catalysts were responsible for the catalytic transfer hydrogenolysis.
基金support from the National Natural Science Foundation of China (No. 21871053)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang (No. 2019R01005)the Open Research Fund of School of Chemistry and Chemical Engineering, Henan Normal University (No. 2020ZD04) is gratefully acknowledged
文摘A copper-catalyzed three-component reaction of alkenes,cycloketone oximes and DABCO·(SO_(2))_(2) is de-veloped,which provides a convenient route for the synthesis of diverse(E)-cyanoalkylsulfonyl alkenes in moderate to good yields with excellent regio-and stereoselectivity.A broad substrate scope with ex-cellent functional group tolerance is observed.A plausible radical pathway is proposed,which involves copper-catalyzed ring-opening C–C bond cleavage of O-acyl oxime and insertion of sulfur dioxide.During the reaction process,cyanoalkyl radical and cyanoalkylsulfonyl radical are the key intermediates.
