检索结果-南通市图书馆

Enantioselective Reduction of Prochiral Ketones Catalyed by Oxazaborolidine Derived from L-Cystine

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1997年第8期8卷 679-680页

作者： Xing Shu Li Xiao Ling Zhang Ru Gang Xie(Department of chemistry, sichuan Union {2., chengdu, 610064)(Department of chemistry, sichuan Educational college, chengdu, 610041) Department of chemistry Sichuan Union University Chengdu 610064 China Department of chemistry Sichuan Educational College Chengdu 610041 China

Two new chiral oxazaborolidine derivated from L-cystine have been used to catalyze the enantioselective reduction of prochiral ketones and the secondary alcohols are obtained with good to excellent opitical yields.

关键词： Enantioselective Reduction of Prochiral Ketones Catalyed by Oxazaborolidine Derived from L-Cystine

Density functional study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2006年第4期49卷 296-307页

作者： LI Ming1, ZHENG Wenxu2.& TIAN Anmin2.1. Department of chemistry, Southwest-China Normal university, Chongqing 400715, China 2. Department of chemistry, sichuan university, chengdu 610064, China 1. Department of chemistry Southwest-China Normal University Chongqing 400715 China 2. Department of chemistry Sichuan University Chengdu 610064 China

The enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine is discussed by the density functional theory (DFT) method. The main intermediates and transition states for this reaction are optimized completely at the B3LYP/6-31g(d) level, and the transition states are verified by vibrational modes. As shown, the chirality-controlled steps for this re- action are the hydride transfer from borane to carbonyl carbon and oxime carbon of keto oxime ether, and the chirality for the reduced products is determined in these two reaction steps. In all examined reaction paths, the first hydride is transferred via a six-membered ring and the second hydride via a five-membered ring or a four-membered ring.

关键词： keto oxime ether, oxazaborolidine, enantioselective reduction, DFT.

Theoretical study of the potential energy surface and the highly excited rovibra-tional spectroscopy of H_2. molecule

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第8期46卷 650-652页

作者： XIE Junkai & YAN GuosenDepartment of chemistry, sichuan Normal {2., chengdu 610066, China Department of chemistry, sichuan university, chengdu 610064, China Department of chemistry Sichuan Normal University Chengdu China Department of chemistry Sichuan University Chengdu China

This note reports the potential energy surface of H2. that has been refined by using SCF-CI approach and the high-resolution experimental data. The calculated splitting values of the local mode vibration states pair close to observed values. This vibration state calculation has shown that there are no obvious non-Born Oppenheimer effects occurring in the lower vibration states of the system.

关键词： potential energy surface local mode vibration state non- Born Oppenheimer effect.

Chromo-chemodosimetric detection for Fe^(2.) by Fenton reagent-induced chromophore-decolorizing of halogenated phenolsulfonphthalein derivatives

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2010年第6期53卷 1398-1405页

作者： ZHENG Kuan,LAI ChengYue,HE LiPing & LI Fang Key Laboratory of Green chemistry and Technology,Ministry of Education college of chemistry,{2.,chengdu 610064,China 1. Key Laboratory of Green chemistry and Technology Ministry of Education College of Chemistry Sichuan University Chengdu 610064 China

A commercially-available sulfonphthalein derivative was demonstrated to be a chemodosimeter for Fe2. and its sensing behavior was further investigated by UV-vis spectroscopy in aqueous media under the optimum *** the presence of chlorophenol red (CPR) and H2.2.the absorption maximum at 435 nm decreased upon addition of Fe2.,resulting in a significant color change of the CPR solution from yellow to *** chemosensor system did not show significant responses to a series of other metal ions including Al3+,Zn2.,Cd2.,Hg2.,Mn2.,Co2.,Fe3+,Ni2.,Cu2.,La3+,Ce4+,Th4+,Pd2.,Pb2.,Sb3+,Cr3+,Au3+,Ag+,Nd3+,Sm3+,alkali and alkaline earth metal cations,allowing for highly selective naked-eye detection of Fe2..Quantitative analysis was carried out kinetically for practicable the Fe2. assay when either fixed time method or the initial rate method was *** the detecting time was set,the decrease of absorbance signal was linear with Fe2. concentration in the range of 0 to 7.50 × 10-5 mol L-1 and the regression equation was ΔA = 0.00759 + 0.00593CFe with a correlation coefficient r = *** chemodosimetric system has employed an irreversible Fenton reagent-promoted oxidation of the CPR free chromophore and the hydroxyl radicals were generated in the presence of both Fe2. and hydrogen *** mechanistic interpretation of the signaling process was partially confirmed by the radical scavenging experiment and the FT-IR analysis of the intermediates formed at different reaction periods.

关键词： colorimetric chemosensor ferrous ion sulfonphthalein Fenton reagent

Interaction of bis-aryl functionalized molecules with nucleosides and nucleic acids

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2010年第1期53卷 103-112页

作者： HUANG Yu1,LIU JunLiang1,ZHANG Ji1,LIU Qiang1,HOU JiTing1,ZHANG Yu1,ZHANG DaWei2.LU QiaoSen1,CHEN ShanYong1,LIN HongHui2.& YU XiaoQi1 1 Key Laboratory of Green chemistry and Technology,Ministry of Education college of chemistry,{2.,chengdu 610064,China 2.Key Laboratory of Bio-resources and Eco-environment,Ministry of Education college of Life Sciences,{2.,chengdu 610064,China. 1. Key Laboratory of Green chemistry and Technology Ministry of Education college of chemistry Sichuan University Chengdu 610064 China2. Key Laboratory of Bio-resources and Eco-environment Ministry of Education college of Life Sciences Sichuan University Chengdu 610064 China

A series of novel molecules with a cyclen(1,4,7,10-tetraazacyclododecane) moiety appended on and bearing different aromatic fragments in the structures were synthesized and *** binding activities of these compounds towards DNA were systematically studied by spectroscopic,viscometric and gel electrophoresis *** results suggest that the stacking interaction plays an important role in improving the DNA binding ability of the *** binding modes of the compounds towards DNA are also affected by the sizes of the aromatic *** binding interaction between binaphthyl compound 1b and several nucleosides was studied by fluorescence *** interaction and hydrophobic interaction play the key role in such non-selective binding process.

关键词： stacking and hydrophobic interactions DNA binding aromatic compounds nucleosides oligonucleotides

Cardinal invariants associated with Fubini product of ideals

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2010年第2期53卷 425-430页

作者： HONG JianYong & ZHANG ShuGuo college of Mathematics, sichuan university, {2., China 1. college of Mathematics Sichuan University Chengdu 610064 China

We prove some results displaying the relationship between Fubini product of ideals and its factor ideals, and study a partial order using the cardinal invariant of the continuum. The relationships among transitive car... 详细信息

关键词： cardinal invariant continuum Fubini product

On nulls of perturbed Fredholm operators and degenerate homoclinic bifurcations

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2004年第4期47卷 617-627页

作者： ZHANG WeinianDepartment of Mathematics, sichuan university, chengdu 610064, China 1. Department of Mathematics Sichuan University 610064 Chengdu China

It is known that small perturbations of a Fredholm operatorL have nulls of dimension not larger than dimN(L). In this paper for any given positive integer κ ? dimN(L) we prove that there is a perturbation ofL which has an exactly κ-dimensional null. Actually, our proof gives a construction of the perturbation. We further apply our result to concrete examples of differential equations with degenerate homoclinic orbits, showing how many independent homoclinic orbits can be bifurcated from a perturbation.

关键词： Fredholm operator, perturbation, dimension, decomposition, degenerate homoclinic bifurcation.

Synthesis of Novel Cyclodextrin Dimers Linked by Multidentate Coordination Units

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1998年第2期9卷 135-138页

作者： Mei Ming LUO Ru Gang XIE Wei LU ping Fang XLA Hua Ming ZHAO (Department of chemistry, sichuan university, {2.Department of chemistry, sichuan Educational college, chengdu 610041) sichuan Univ Dept Chem Chengdu 610064 Peoples R China sichuan Educ Coll Dept Chem Chengdu 610041 Peoples R China

A new type of cyclodextrin dimers (2.-c) bridged with multidentate coordination units has been synthesized by treatment of 6-deoxy-6-hydroxyethylamino-beta-cyclodextrin 1 with corresponding dibromides in the presence ... 详细信息

关键词： cyclodextrin dimers selective synthesis

γ-Hydroxy-α,β-acetylenic esters:asymmetric syntheses and applications

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2010年第1期53卷 21-35页

作者： GAO Ge1 & PU Lin2.1Department of chemistry,sichuan university,{2.,China 2.epartment of chemistry,university of Virginia,Charlottesville,Virginia 2.904-4319,USA 1. Department of chemistry Sichuan University Chengdu 610064 China2. Department of Chemistry University of Virginia Charlottesville Virginia 22904-4319 USA

γ-Hydroxy-α,β-acetylenic esters are versatile synthetic precursors to many organic *** paper reviews the synthesis of chiral γ-hydroxy-α,β-acetylenic esters by asymmetric reduction of γ-oxo-α,β-acetylenic esters,enantioselective addition to aldehydes in the presence of chiral catalysts,and diastereoselective addition to chiral *** preparation of racemic γ-hydroxy-α,β-acetylenic esters is also *** are provided for the application of γ-hydroxy-α,β-acetylenic esters in organic synthesis.

关键词： γ-hydroxy-α β-acetylenic ester asymmetric enantioselective diastereoselective