检索结果-南通市图书馆

Chinese Journal of Chemistry 2019年第7期37卷 647-656页

作者： Qi Zhang Bing-Feng Shi Department of Chemistry Zhejiang University Hangzhou Zhejiang 310027 China

What is the most favorite and original chemistry developed in your research group? Developing PIP amine for regio-and enantioselective methylene C-H activation. How do you get into this specific field? Could you pleas... 详细信息

关键词： regioselectivity Stereoselectivity

Nickel-catalyzed regioselective B(3,4,5,6)-H tetra-alkylation of o-carboranes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国科学:化学英文版 2023年第10期66卷 2836-2841页

作者： Jianwei Zhao Zuowei Xie Department of Chemistry and State Key Laboratory of Synthetic Chemistry The Chinese University of Hong KongHong Kong 999077China Shenzhen Grubbs Institute and Department of Chemistry Southern University of Science and TechnologyShenzhen 518055China

Though transition metal-catalyzed cage BH methylation has been well documented, catalytic alkylation of cage BH bonds remained elusive because transition metal alkyl complexes are prone to undergo β-H elimination. We report herein a highly efficient 8-aminoquinoline-assisted nickel-catalyzed regioselective cage B(3,4,5,6)-H tetra-alkylation of o-carboranes employing unactivated alkyl bromides as alkylating agents in the absence of any oxidants, leading to the preparation of a class of tetra-alkylated o-carboranes with a broad substrate scope in good to very high yields. This method opens new avenues for oxidant-free, direct, efficient, sustainable, and regioselective multiple B–H alkylation of carboranes via base metal catalysis.

关键词： nickel catalysis B-H activation carborane alkylation regioselectivity

Synthesis of rac-α-aryl propionaldehydes via branched-selective hydroformylation of terminal arylalkenes using water-soluble Rh-PNP catalyst

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第2期33卷 830-834页

作者： Peng Gao Miaolin Ke Tong Ru Guanfeng Liang Fen-Er Chen Department of Chemistry Sichuan UniversityChengdu 610064China Department of Chemistry Fudan UniversityShanghai 200433China Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Drugs Fudan UniversityShanghai 200433China

This work detailed the preparation of a class of water-soluble PNP ligands that differed by the nature of the substitute on phenyl ring of ligands. These ligands were incorporated into water-soluble rhodium-PNP complex catalysts that were used to regioselective hydroformylation of a series of terminal arylalkenes,providing efficient access to rac-α-aryl propionaldehydes in good to excellent yield(up to 97%) and branched-regioselectivity(up to 40:1 b/l ratio). Furthermore, gram-scale and diverse synthetic transformation demonstrated synthetic application of this methodology for non-steroidal antiinflammatory drugs.

关键词： Aryl propionaldehydes Hydroformylation Water-soluble PNP ligands regioselectivity Rhodium

Convenient and efficient access to tri-and tetra-substituted 4-fluoropyridines via a[3+2]/[2+1]cyclization reaction

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第6期33卷 2982-2986页

作者： Xuejiao Tang Kun Liu Zeming Qu Junyan Zhan Rukui Zhu Fan Teng Lili Meng Yanmin Huang Chusheng Huang Yimiao He Qiang Zhu Guangxi Key Laboratory of Natural Polymer Chemistry and Physics College of Chemistry and MaterialsNanning Normal UniversityNanning 530001China Guangzhou Institutes of Biomedicine and Health Chinese Academy of SciencesGuangzhou 510530China Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle Nanchang Hangkong UniversityNanchang 330063China

A[3+2]/[2+1]cycloaddition reaction of gem–difluorocyclopropenes is presented,offering a mild and efficient approach to accessing tri-and tetra-substituted 4-fluoropyridines in moderate to good yields with excellent regioselectivity.Multiple synthetic applications,including process-scale reactions,modification of bioactive molecules,derivatization reactions and synthesis of the analogue of the PKM2 modulator,are subsequently described.

关键词： 4-Fluoropyridine gem-Difluorocyclopropene [3+2]/[2+1]cyclization reaction DMSO as an oxidant regioselectivity PKM2 modulator

Integrating aryl chlorides into nickel-catalyzed 1,1-difunctionalization of alkenes

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第12期33卷 5096-5100页

作者： Caocao Sun Guoyin Yin The Institute for Advanced Studies Wuhan UniversityWuhan 430072China

Difunctionalization of alkenes have developed into an important type of reactions for rapidly and efficiently assemble complex molecules.While extensive advancements have been achieved by the assistance of transition metal catalysis,the employment of cheap,abundant aryl chlorides as coupling partner is still a challenging task in this field.Herein,we report our first achievement in 1,1-difunctionalization of alkenes with aryl chlorides as coupling partners.The success is predominantly ascribed to the judicious selection of 1,2-diamine ligand.This study provides an efficient protocol for the synthesis of secondary benzyl boronates from easily accessible feedstock chemicals.Furthermore,the distinguished features of this method include excellent 1,1-regio-and chemoselectivity,good functional group tolerance and easily-operational catalytic reaction conditions.

关键词： Aryl chlorides Difunctionalization of alkenes regioselectivity Nickel catalysis

A New Approach to Ethyl 1-Aroyl/Aroylmethyl-5-methyl-3- methylthiopyrazole-4-carboxylates: High regioselectivity in Alkylation and Acylation Reactions between N-1 and N-2 of a Pyrazole Derivative

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2005年第9期16卷 1161-1164页

作者： Li Rong WEN Gui Long ZHAO Ming LI Wen Ying QI Xiu Li ZHANG Hua Zheng YANG College of Chemistry and Molecular Engineering Qingdao University of Science and Technology Qingdao 266042 State Key Laboratory of Elemento-organic Chemistry Institute of Elemento-Organic Chemistry Nankai University Tianjin 300071 Ocean Food and Drug Institute Ocean University of China Qingdao 266003

Two series, totalizing twelve, of new compounds, ethyl 1-aroyl/aroylmethyl- 5-methyl-3-methylthiopyrazole-4-carboxylates 5/6, have been synthesized via highly regioselective acylation and alkylation of ethyl 3-methyl-5-methylthio- 1H-pyrazole-4-carboxylate 2a with aroyl chloride 3 and alpha- tosyloxysubstitutedacetophenones 4. Unexpected structures of the product have been unambiguously determined by both X-ray crystallographic analysis and 2D NMR.

关键词： Pyrazole regioselectivity X-ray crystallographic analysis 2D NMR

Stereoselective Synthesis of Nontethered trans-4 Bis(aziridino)[60]fullerene Derivatives

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2023年第18期41卷 2282-2288页

作者： Jie Xiong Shuang Feng Rufang Peng Bo Jin State Key Laboratory of Environment-friendly Energy Materials Southwest University of Science and TechnologyMianyangSichuan 621010China

Comprehensive Summary,The stereoselective preparation of fullerene bis-adducts through nontethered methods remains difficult due to the significant amount of regioisomers produced.The trans-4 aziridino[60]fullerenes,C_(60)(NC_(6)H_(4)R)n(n=1 or 2,R=OMe,OEt,OBu),were selectively synthesized even without a catalyst by reacting octabromofullerene with the corresponding aniline.Nuclear magnetic resonance spectroscopy,UV-vis spectroscopy,and X-ray structural analysis provided convincing characterization of the compounds.A possible reaction process was proposed to clarify the synthesis of highly regioselective trans-4-bisaziridino[60]fullerenes.The possible application of these aziridino[60]fullerene derivatives as propellant stabilizers was also explored.

关键词： Fullerene regioselectivity Mechanism Nitrocellulose Stability

Transition Metal Catalyzed Enantioselective Migratory Functionalization Reactions of Alkenes through Chain-Walking

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2022年第13期40卷 1608-1622页

作者： Min Zhang Yuqi Ji Chun Zzhang Institute of Molecular Plus Tianjin Key Laboratory of Molecular Optoelectronic ScienceDepartment of ChemistrySchool of ScienceTianjin UniversityWejin Rd.92Tianjin 300072China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

"Chain-walking"reactions could realize to modify a molecule at the position far awayfrom the active site.It has been a hot topic in the research field of organic synthesis.As a number of achievements have been made by researchers,the products of transition metal-catalyzed chain-walking reactions couldbe obtained with good enantioselectivity.This review summarized the researches on the asymmetric chain-walking reactions catalyzed by transition metal in the past decade.These works are classified according to the species of metal catalysts.

关键词： Chain-walking Transition-metal catalysis Enantioselectivity regioselectivity Diastereoselectivity

Pd-Catalyzed Asymmetric Allylic C—H Functionalization

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2023年第15期41卷 1841-1848页

作者： Pu-Sheng Wang Liu-Zhu Gong Department of Chemistry University of Science and Technology of ChinaHefeiAnhui 230026China Center for Excellence in Molecular Synthesis of CAS University of Science and Technology of ChinaHefeiAnhui 230026China

Comprehensive Summary Pd-catalyzed asymmetric allylic C—H functionalization has emerged as a powerful tool to access chiral,densely functionalized molecules from easily accessible alkenes,enabling the increase of the step-or atom-economy by minimizing functional group manipulations for preparing allylating reagents.Due to the inadequacy of stereoselection strategies,the asymmetric allylic C—H functionalization is still in the early stage.In this essay,we will describe our journey to identification of asymmetric catalytic systems,mechanism of allylic C—H activation,control of stereo-and regioselectivity,and applications in asymmetric synthesis.

关键词： C-H activation Asymmetric catalysis Allylation Palladium Allylic compounds regioselectivity Alkenes

Mechanistic study on the regioselectivity of Co-catalyzed hydroacylation of 1,3-dienes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2015年第1期26卷 58-62页

作者： Yuan-Ye Jiang Hai-Zhu Yu Jing Shi Department of Chemistry University of Science and Technology of China Department of Polymer Science and Engineering University of Science and Technology Beijing

Density functional theory（DFT） method was used to explore the origin of the regioselectivity of Cocatalyzed hydroacylation of 1,3-dienes.The reaction of 2-methyl-1,3-butadiene and benzaldehyde with1,3-bis（diphenylphosphino）propane ligand was chosen as the model reaction.The energies of the intermediates and transition states in the stages of oxidative cyclization,β-H elimination and C-H reductive elimination were investigated.Computational results show that β-H elimination is the ratedetermining step for the whole catalytic cycle.C1-Selective oxidative cyclization is favored over C4-selective oxidative cyclization.Besides.C4-selective oxidative cyclization is kinetically disfavored than all the steps in C1-hydroacylation mechanisms,consistent with the experimentally obtained C1-selective hydroacylation products.Analyzing the reason for such observation,we suggest that both electronic and steric effects contribute to the C1-selectivity.On the electronic aspect,C1 is more electron rich than C4 due to the methyl group on C2,which makes the electrophilic attack of aldehyde carbon on C1 more favorable.On the steric aspect,the methyl group locates farther from the ligands in the transition state of C1-selective oxidative cyclization than in that of C4-selective oxidative cyclization.

关键词： Density functional theory Cobalt regioselectivity Hydroacylation