C2型轴对称手性双恶唑啉的合成及其应用研究

本文综述了手性双恶唑啉的合成及其金属配合物作为手性催化剂在催化不对称反应中的应用研究进展。     

牛血清蛋白对手性物质的毛细管电泳拆分

采用聚氧乙烯涂层毛细管柱，以牛血清蛋白(BSA)为手性添加剂，运用毛细管电泳电导检测对手性药物沙丁胺醇和多沙唑嗪以及DL-组氨酸、色氨酸、苏氨酸进行拆分。考察了涂层柱的稳定性和重现性。对影响手性分离的主要因素：缓冲溶液的浓度和酸度、BSA的浓度、有机溶剂的种类和浓度以及分离电压进行了系统的研究。结果表明：在选择的最佳实验条件下，各对映异构体在22min内得到基线分离。     

β—环糊精对D／L—酪氨酸对映体的手性识别及超分子包合物的合成

利用圆二色谱研究了β－环糊精（β－ＣＤ）对Ｄ／Ｌ酪氨酸的手性识别行为，制备出了β－ＣＤ与Ｌ－酪氨酸（Ｌ－Ｔｙｒ）的固体超分子化合物，并用元素分析、薄层分析、Ｘ射线粉末衍射及热分析对包合物进行了表征，用荧光光谱法测定了包合物的形成常数．实验结果表明，β－ＣＤ具有选择包结Ｌ－酪氨酸的特性；主客体形成１１的包合物，其组成为Ｌ－Ｔｙｒ／β－ＣＤ·１２Ｈ２Ｏ；稳定常数为５．１３×１０３Ｌ／ｍｏｌ；包合物的热稳定性比主客体皆有改善     

含松香骨架的新型手性季铵盐相转移催化剂的合成及其在不对称环氧化反应中的应用

以天然松香为原料合成了4个新型手性季铵盐类相转移催化剂, 并用于催化不对称查尔酮环氧化反应, 发现这类手性相转移催化剂可以有效地催化查尔酮的不对称环氧化, 环氧化产物ee最高达20%.     

Carbon dioxide supercritical fluid chromatography-Fourier transform infrared spectrometry

Summary The coupling of carbon dioxide supercritical fluid chromatography with Fourier transform infrared spectrometry (SFC-FTIR) is a powerful tool for the separation and on-line identification of non-volatile compounds. The IR transparency of carbon dioxide in the Fermi resonance bands region versus its density has been studied. Functional groups with stretching vibrations outside the transparent window of carbon dioxide are examined. SFC-FTIR separations allow Gram-Schmidt reconstruction chromatograms or IR window chemigrams with high quality spectra to be obtained. This SFC-FTIR lightpipe (flow cell, beam condensing optics, narrow band detector) has allowed detection limits of 250ng for benzonitrile and 70ng for methyl benzoate to be reached. The feasibility of very rapid SFC-FTIR separations is shown along with the subsequent peak spectra.     

阿苯达唑亚砜对映异构体的高效毛细管电泳手性拆分

建立了高效毛细管电泳拆分阿苯达唑亚砜对映体的方法，考察了背景电解质pH、环糊精种类和浓度，有机改性剂种类和浓度对分离的影响，对分离条件进行了优化。实验结果表明：在含36g/L磺化β－环糊精和10％甲醇的20mmol/L Tris-H3PO4(pH2.5）缓冲体系中，阿苯达唑亚砜对映体具有良好的分离效果。     

Enantiomer differentiation in intramolecular carbon—hydrogen insertion reactions of racemic secondary alkyl diazoacetates catalyzed by chiral dirhodium(ii) carboxamidates

Highly efficient kinetic resolution of racemic secondary alkyl diazoacetates in intramolecular carbon-hydrogen insertion reactions has been achieved using chiral dirhodium(ii) carboxamidates. Products formed from catalytic diazo decomposition of racemic 2-octyl diazoacetate and, separately, its (2R)- and (2S)-enantiomeric forms, as well as bothcis- andtrans-2-methylcyclohexyl diazoacetates, have been systematically evaluated. Enantioselectivities up to 99 %ee have been obtained for -lactone formation. -Lactone production has been observed and, although minor with cyclohexyl diazoacetates, is the major insertion pathway for diazo decomposition of 2-octyl diazoacetate.Dedicated to Academician of the RAS N. S. Zefirov (on his 60th birthday).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1798–1803, September, 1995.Financial support for this research from the National Institutes of Health (GM 46503) and the National Science Foundation of the United States is gratefully acknowledged. We thank D. A. Pierson for her preparation of 2-methylcyclohexyl diazoacetates and preliminary studies of their diazo decomposition and A. Melekhov from the Higher College of Chemistry for his preparation and catalytic studies of rac-2-octyl diazoacetate.     

Effective electromagnetic and chiral parameters of chiral composite material

The effective parameters of chiral composite are studied using a simple model, that is, randomly oriented non-interacting wire helices embedded in a nonchiral host medium. It is found that both the effective permittivity and permeability are independent on the handedness of the chiral objects while the effective chirality admittance is dependent. It is also found that when the ratio of the radius of the chiral helix to its pitch is about 0.23, maximum chirality admittance is achieved. The effective parameters of equichiral sample are also discussed.     

Synthesis and X-ray analysis of 1-((1S)-phenylethyl)-azetidine-(2R)-piperidinamide

The crystal and molecular structure of a new azetidine-2-carboxylic amide derivative is described. The structure was solved by direct methods and refined by least squares methods toR1=0.0393 for 4264 reflections (withI>2(I)) The structure consists of two independent molecules which are chemically the same with slight differences in geometry. Crystal data: C₁₇H₂₄N₂O, monoclinic, space groupP2₁,a=8.3782(4),b=20.0342(13),c=9.7769(8) Å, =109.687(6)°,V=1545.1(2)ų,Z=4.     

Glass capillary gas chromatography of amino acid enantiomers

Glass capillaries coated with Chirasil-Val, a chirally functionalised polysiloxane, are capable in principle of resolving all protein amino-acid enantiomers in a single run and within a short analysis time, thus allowing for example the quantitative amino acid determination by enantiomer labelling. The elution characteristics of the individual amino acids however are also dependent upon the chemical nature of the capillary wall surface, and a surface pretreatment is found to be necessary if all protein amino acids are to be analysed. Of the various methods of pretreatment tested, etching of borosilicate glass with gaseous HCl followed by deposition of colloidal silicic acid is considered to be the most suitable.