检索结果-南通市图书馆

Palladium-catalyzed oxidative cyclopropanation of enamides and norbornenes initiated by C–H activation

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2018年第6期61卷 695-701页

作者： Ming Chen Mi-Na Zhao Yao-Du Zhang Zhi-hui Ren zheng-hui guan Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Department of Chemistry & Materials Science Northwest University Shaanxi Key Laboratory of Phytochemistry College of Chemistry and Chemical Engineering Baoji University of Arts and Sciences

A novel palladium-catalyzed oxidative cyclopropanation of enamides and norbornenes has been developed. The reaction proceeded through palladium-catalyzed vinyl C–H bond activation of enamides followed by two migratory insertions, β-(N)H elimination and hydrolyzation cascade steps. The reaction tolerates a range of functional groups and provides an effective method for the synthesis of cyclopropane-fused norbornanes in good yields under mild conditions.

关键词： palladium-catalyzed cyclopropanation C–H activation enamides norbornenes

PhI(OAc)2-promoted umpolung acetoxylation of enamides for the synthesis of α-acetoxy ketones

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2017年第6期60卷 761-768页

作者： Ming Chen Wei Zhang Zhi-hui Ren Wen-Yun Gao Yao-Yu Wang zheng-hui guan Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Department of Chemistry & Materials Science Northwest University Xi'an 710127 China College of Life Sciences/National Engineering Research Center for Miniaturized Detection Systems Northwest University Xi 'an 710069 China

Umpolung is a fundamental concept in organic chemistry, which provides an alternative strategy for the synthesis of target compounds which were not easily accessible by conventional methods. Herein, a mild and efficient PhI(OAc)_2-promoted umpolung acetoxylation reactions of enamides was developed for the synthesis of α-acetoxy ketones. The reaction tolerates a wide range of functional groups and affords α-acetoxy ketones in good to excellent yields. PhI(OAc)_2 serves as a source of acetoxy in the reaction.

关键词： umpolung enamides acetoxylation hypervalent iodine reagents α-acetoxy ketones

Base-mediated formal [3＋2] cycloaddition of β,γ-alkenyl esters and p-TsN3 for the synthesis of pyrazoles

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2017年第7期62卷 493-496页

作者： Mi-Na Zhao Mei-Na Zhang Zhi-hui Ren Yao-Yu Wang zheng-hui guan Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Department of Chemistry & Materials ScienceNorthwest University

A novel 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU)-mediated formal cycloaddition of β,γ-alkenyl esters with p-tolylsulfonylazide(p-TsN_3) for the synthesis of 3,5-disubstituted pyrazoles has been *** reaction proceeded through diazotization of β,γ-alkenyl esters sequential with thermodynamic cyclization.p-Tolylsulfonylazide played a role as a source of two-nitrogen *** reaction employs readily available starting materials,tolerates a wide range of functional groups,and proceeds under mild conditions.

关键词： Synthetic methods Cycloaddition β,γ-Alkenylesters p-Tolylsulfonylazide Pyrazoles

Palladium-Catalyzed Asymmetric Domino Heck/Carbocyclization/Suzuki Reaction:A Dearomatization of Nonactivated Naphthalenes

在线全文

学校读者我要写书评

暂无评论

CCS Chemistry 2021年第12期3卷 69-77页

作者： Ming Chen Xucai Wang Zhi-hui Ren zheng-hui guan Key Laboratory of Synthetic and Nature Molecule of Ministry of Education Department of Chemistry and Materials ScienceNorthwest UniversityXi’an 710127

Herein,we report a novel palladium(Pd)-catalyzed asymmetric domino Heck/carbocyclization/Suzuki reaction of N-(2-bromoaryl)-*** reaction involves a novel and enantioselective dearomative 1,2-insertion of the naphthalene group,thus providing a unique dearomatization strategy of nonactivated naphthalenes.A new phosphoramidite ligand L12,which displayed excellent reactivity and enantioselectivity in the reaction,has been developed.

关键词： asymmetric catalysis palladium-catalyzed domino Heck reaction dearomatization nonactivated naphthalenes

Asymmetric Spirocyclization Enabled by Iridium and Brønsted Acid-Catalyzed Formal Reductive Cycloaddition

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CCS Chemistry 2021年第7期3卷 1775-1786页

作者： Nan-Fang Mo Le Yu Ying Zhang Ya-Hong Yao Xun Kou Zhi-hui Ren zheng-hui guan Key Laboratory of Synthetic and Natural Functional Molecule of Ministry of Education Department of Chemistry&Materials ScienceNorthwest UniversityXi’an 710127

A catalytic,enantioselective spirocyclization of formanilides or formylindolines and enamides has been developed *** reaction proceeds through a sequential iridium-catalyzed hydrosilylation of tertiary formanilides and a chiral phosphoric acid-catalyzed formal cycloaddition of exocyclic enamides,thus providing straightforward access to a diverse array of enantioenriched azaspirocycles under mild conditions.

关键词： asymmetric catalysis formanilides azaspirocycles chiral phosphoric acid enamides

Palladium-Catalyzed Carbonylation of C-H Bonds for the Synthesis of Carbonyl Compounds

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Palladium-Catalyzed Carbonylation of C-H Bonds for the Synth...

Automatic Requirement Dependency Extraction Based on Integrated Active Learning Strategies

中国化学会第十四届全国有机合成化学学术研讨会

作者： zheng-hui guan Department of Chemistry & Materials Science Northwest University

Carbonylation reactions have proven to be powerful tools for construction of carbonyl compounds. However, transition metal catalyzed carbonylation of C-H bonds with CO remains challenging. In recent years, we have developed palladium-catalyzed carbonylation reactions of various anilines and enamides. Especially, palladium-catalyzed C-H/N-H double carbonylation of secondary alkyl anilines was developed for straightforward synthesis of isatoic anhydrides, and carbonylation of alkenyl C-H bonds of enamides was developed for the synthesis of 1,3-oxazin-6-ones. Furthermore, palladium-catalyzed carbonylative Suzuki-Miyaura coupling of indole and phenyl boronic acid in the presence of I was developed for the synthesis of indol-3-yl aryl ketones. Very recently, palladium-catalyzed regioselective oxidative carbonylation of tri-substituted alkenes with CO and alcohols for the synthesis of α,β-unsaturated esters has been developed. The experiment results and DFT calculations suggested that the oxidative carbonylation proceeded through alkoxylation of palladium catalyst, CO and alkenyl C=C double bond migratory insertion, β-(N)H elimination and tautomerization cascade steps.

关键词： palladium-catalyzed carbonylation enamines C-H activation

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Machine Intelligence Research 2024年第5期21卷 993-1010页

作者： hui guan Guorong Cai Hang Xu Department of Computer Science and Technology Shenyang University of Chemical TechnologyShenyang110142China Key Laboratory of Industrial Intelligence Technology on Chemical Process Shenyang110142China

Since requirement dependency extraction is a cognitively challenging and error-prone task,this paper proposes an automatic requirement dependency extraction method based on integrated active learning *** this paper,the coefficient of variation method was used to determine the corresponding weight of the impact factors from three different angles:uncertainty probability,text similarity difference degree and active learning variant prediction divergence *** combining the three factors with the proposed calculation formula to measure the information value of dependency pairs,the top K dependency pairs with the highest comprehensive evaluation value are selected as the optimal *** the optimal samples are continuously added into the initial training set,the performance of the active learning model using different dependency features for requirement dependency extraction is rapidly ***,compared with other active learning strategies,a higher evaluation measure of requirement dependency extraction can be achieved by using the same number of ***,the proposed method using the PV-DM dependency feature improves the weight-F1 by 2.71%,the weight-recall by 2.45%,and the weight-precision by 2.64%in comparison with other strategies,saving approximately 46%of the labelled data compared with the machine learning approach.

关键词： Requirement dependency dependency extraction dependency features integrated active learning strategies coefficient of variation

Clinical and genetic study of spinocerebellar ataxia type 7 in East Asian population

维普期刊数据库评论

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 Medical Journal 2010年第16期123卷 2274-2278页

作者： HAN Yan YU Long zheng hui-min guan Yang-tai Department of Neurology Changhai Hospital Second Military Medical University Shanghai 200433 China

Background Spinocerebellar ataxia type 7 （SCA7） is known as an autosomal dominant cerebellar ataxia; patients with genetically confirmed diagnoses of SCA7 have increased rapidly in recent ***, SCA7 is a rare subtype of SCA, and most data available about SCA7 are those of white *** aim of the present study was to systematically review the prevalence and clinical and genetic aspects of SCA7 patients in East Asian *** A search for publications on SCA7 was performed by using the ＂PubMed＂ database with the published language limited in *** mainly focusing on the prevalence of SCA7 in patients with SCA and the clinical and genetic features of SCA7 patients were fully reviewed and *** The prevalence of SCA7 in SCA patients ranged from 0 to 7.7%, which was similar to those reported *** clinical manifestations were typically present at the 30＇s of its victims （median, 29 years; interquartile range （IQR）,19.5-36.5 years）, and the symptoms appeared 15 years （（15.17±4.22） years） earlier on average in the offspring than in the *** ataxia and visual impairment were both found in all patients of whom the clinical features were *** SCA7 alleles contained 40-100 CAG repeats, with a median of 47 repeats （IQR, 44.5-50.0）; and the offspring had 13 more repeats on average compared with their parents （12.62±19.03）.A strong negative correlation was found between CAG repeat size and the onset age of patients （r=-0.739, P=0.000）.In addition, no significant difference was found in CAG repeat sizes between patients with visual impairment as the initial symptom and those with gait disturbance as their initial symptom （P=0.476）.Conclusions The prevalence of SCA7 in SCA patients, the age at onset and CAG repeats of SCA7 patients in East Asia are consistent with those of white ***, larger population study is needed to assess the correlation between the CAG repeat size and initial symptoms of

关键词： spinocerebellar ataxia type 7 East Asia clinical features genetics

Review on synergistic damage effect of irradiation and corrosion on reactor structural alloys

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第3期35卷 109-141页

作者： hui Liu guan-Hong Lei He-Fei Huang Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China

The synergistic damage effect of irradiation and corrosion of reactor structural materials has been a prominent research *** paper provides a comprehensive review of the synergistic effects on the third-and fourth-generation fission nuclear energy structural materials used in pressurized water reactors and molten salt *** competitive mechanisms of multiple influencing factors,such as the irradiation dose,corrosion type,and environmental temperature,are summarized in this *** approaches are proposed to alleviate the synergistic damage caused by irradiation and corrosion,thereby promoting in-depth research in the future and solving this key challenge for the structural materials used in reactors.

关键词： Irradiation and corrosion Synergistic effect Austenitic stainless steels Nickel-based alloys Reactors