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Chinese Journal of Polymer Science 2024年第4期42卷 501-510页

作者： Giovanni Ricci Anna Sommazzi Francesco Masi Alessandra Forni CNR-Istituto di Scienze e Tecnologie Molecolari“Giulio Natta”(SCITEC) via A.Corti 1220133MilanoItaly Viale Giovanni XXIII 34 I-28100NovaraNOItaly Via Galvani 7 I-26866Sant’Angelo LodigianoLOItaly CNR-Istituto di Scienze e Tecnologie Molecolari“Giulio Natta”(SCITEC) via C.Golgi 1920133MilanoItaly

Several novel cobalt dichloride complexes with amino-phosphine bidentate ligands were synthesized and characterized.For some of them single crystals were obtained and their molecular structure was determined by X-ray diffraction method.All the complexes were then used in combination with MAO for the polymerization of 1,3-butadiene,obtaining polymers with different structures(i.e.,predominantly 1,2 or cis-1,4)mainly depending on the type of ligand and on the MAO/Co molar ratio.The behavior of these novel catalysts was compared with that exhibited,in the polymerization of the same monomer,by the systems CoCl_(2)(PR3)2-MAO and CoCl_(2)(PRPh2)2-MAO(R=alkyl or cycloalkyl group),and by the systems based on cobalt dichloride complexes with various bi-and tridentate ligands(e.g.,diphosphines,bis-imines,pyridyl-imines,bis-iminopyridines).The comparison between the different systems allowed us to make some clarity about the actual and effective role played by the various types of ligands in the polymerization of conjugated dienes with catalytic systems CoCl_(2)(L)-MAO,in which L=mono-,bi-,or tri-dentate ligand.

关键词： 1,3-Butadiene Stereospecific polymerization Cobalt catalysts Regioselectivity Aminophosphine ligands Crystal structures Chelate rings

Post-spin crossing dynamics determine the Regioselectivity in open-shell singlet biradical recombination

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Organic Chemistry Frontiers 2022年第4期9卷 995-1003页

作者： Min Zhu Chao Zheng State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of Sciences345 Lingling LuShanghai 200032China School of Physical Science and Technology ShanghaiTech University100 Haike RoadShanghai 201210China

Radical recombination is among the fastest reactions in organic chemistry.Achieving high levels of selectivity in this type of reaction is rather challenging.In a recent report on visible-light-induced dearo-mative cycloaddition of pyrrole-tethered vinylcyclopropanes,extraordinary Regioselectivity was observed during the intramolecular open-shell singlet biradical recombination step.

关键词： singlet radical Regioselectivity

Structure-guided manipulation of the Regioselectivity of the cyclosporine A hydroxylase CYP-sb21 from Sebekia benihana

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Synthetic and Systems Biotechnology 2020年第3期5卷 236-243页

作者： Fengwei Li Li Ma Xingwang Zhang Jingfei Chen Feifei Qi Yinyue Huang Zepeng Qu Lishan Yao Wei Zhang Eung-Soo Kim Shengying Li State Key Laboratory of Microbial Technology Shandong UniversityQingdaoShandong266237China Shandong Provincial Key Laboratory of Synthetic Biology CAS Key Laboratory of BiofuelsQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdaoShandong266101China Department of Biological Engineering Inha UniversityIncheon22212South Korea Laboratory for Marine Biology and Biotechnology Qingdao National Laboratory for Marine Science and TechnologyQingdaoShandong266237China

The cytochrome P450 enzyme CYP-sb21 from the rare actinomycete Sebekia benihana is capable of hydroxylating the immunosuppressive drug molecule cyclosporine A(CsA)primarily at the 4th N-methyl leucine(MeLeu4),giving rise toγ-hydroxy-N-methyl-L-Leu4-CsA(CsA-4-OH).This oxidative modification of CsA leads to dramatically reduced immunosuppressive activity while retaining the hair growth-promoting side-effect,thus demonstrating great application potential in both pharmaceutical and cosmetic industries.However,this P450 enzyme also hydroxylates CsA at the unwanted position of the 9th N-methyl leucine(MeLeu9),indicating that the Regioselectivity needs to be improved for the development of CsA-4-OH into a commercial hair growth stimulator.Herein,we report the crystal structure of CYP-sb21 in its substrate-free form at 1.85Å.Together with sequence and 3D structure comparisons,Autodock-based substrate docking,molecular dynamics(MD)simulation,and site-directed mutagenesis,we identified a number of key residues including R294,E264,and M179 that can improve catalytic efficiency or change the Regioselectivity of CYP-sb21 towards CsA,setting the stage for better enzymatic preparation of CsA-4-OH.This study also provides new insights into the substrate recognition and binding mechanism of P450 enzymes that accommodate bulky substrates.

关键词： Cytochrome P450 monooxygenase Crystal structure Cyclosporine A Regioselectivity Hair growth stimulator

From Reactivity and Regioselectivity to Stereoselectivity: An Odyssey of Designing PIP Amine and Related Directing Groups for C-H Activation

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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

Trifluoromethyl Radical Addition versus Radical Trifluoromethylation:Reversed Regioselectivity in Carbotrifluoromethylation of Alkenes

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Chinese Journal of Chemistry 2019年第6期37卷 630-631页

作者： Zhenzhen Zhang Lin Zhu Key Laboratory of Organofluorine Chemistry Center for Excellence in Molecular SynthesisShanghai Institute of Organic ChemistryChinese Academy of Sciences345 Lingling RoadShanghai 200032China

Professor Chaozhong Li's research group has long been interested in radicals in organic synthesis. They have developed a series of silver-catalyzed radical fluorination reactions since the year 2012.[1] In 2015, the research group joined the Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences. I joined the Li group in the same year.

关键词： alkenes radical reactions trifluoromethylation Regioselectivity

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

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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

Regioselectivity Study on Propylene Polymerization Catalyzed by Neutral Salicyladiminato Pd(II) Model Complex with DFT Method

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Chinese Journal of Structural Chemistry 2005年第6期24卷 723-728页

作者： YANGZhao-Di LIUYue LIUYing ChemicalandEnvironmentalEngineeringCollege HarbinUniversityofScienceandTechnology Harbin150080 China SchoolofChemicalEngineeringandTechnology ChinaUniversityofMiningandTechnologyXuzhou221008China

Many attempts have been made to control the Regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The Regioselectivity of propylene polymerization was investigated by replacing a nitrogen atom in the Pd(II) diimine catalyst with an oxygen atom from density functional theory method at the B3LYP/LANL2DZ level. The results show that the 1,2-insertion becomes a rival mechanism to the 2,1-insertion when the nitrogen atom is replaced by the oxygen atom leading to an asymmetric environment in the catalyst, and that the steric effect in the asymmetrical catalyst plays an important part in the polymerization. The insertion barrier from 2-O is much higher than that from 2-N. A pyramid transition state was characterized for the catalyst to convert 2-O back to 2-N through internal rotation. The propylene prefers to coordinate at the opposite side of O in the catalyst. This is the driving force for the internal rotation. The results are significant for isotactic and syndiotactic polymerization.

关键词： Regioselectivity salicyladiminato-Pd(II) catalyst propylene polymerization density functional theory method (DFT)

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

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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

Computational Study on Rh（Ⅲ）-Catalyzed Synthesis of Indolines from Arylnitrones and Alkynes: Origin of Regioselectivity, and Role of Pivalic Acid Additive

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Computational Study on Rh（Ⅲ）-Catalyzed Synthesis of Indol...

Mechanism and Regioselectivity in Gold(Ⅰ)-Catalyzed Intramolecular Hydroarylation of Alkynes

第十三届全国量子化学会议

作者： Hongliang Wang Rongxiu Zhu Chengbu Liu Dongju Zhang Institute of Theoretical Chemistry Shandong University

Density functional theory calculations were performed on Rh（Ⅲ）-catalyzed synthesis of indolines from arylnitrones and alkynes, which provides an efficient method integrating C–H activation with O-atom transfer.The results suggest that the catalytic cycle involves a Rh（Ⅲ）–Rh（I）–Rh（Ⅲ）transformation and consists of C–H activation, alkyne insertion/O-atom transfer,and cyclization-protonation. The C–H activation proceeds via a self-assisted deprotonation mechanism. The calculations located an intermediate containing an enol unit, which plays a crucial role in facilitating the cyclization process.The theoretical results have elucidated 1) the role of internal oxidizing directing group, 2) the origination of the Regioselectivity, and 3) the reason that the presence of pivalic acid importantly improves the yield. The present study provides an explanation for the puzzling experimental observations.

关键词： C–H activation O-atom transfer Regioselectivity

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Mechanism and Regioselectivity in Gold(Ⅰ)-Catalyzed Intramo...