对映体

Herein, we report the enantioselective total syntheses of slagenins A-C and their antipodes. Starting from readily available ethyl -4-chloro-3-hydroxy-butanonate, elongation of the carbon chain with diazomethane, followed by oxidation of the given α-diazoketone using distilled DMD, afforded a key intermediate α-ketoaldehyde .

本文从方便易得的-4-氯-3-羟基-丁酸乙酯出发，经重氮甲烷延伸碳连、DMD氧化相应的α-重氮酮，制得α-酮醛；该化合物与尿素在氢氟酸作用下，以协同方式非对映选择性的直接构建了cis-四氢呋喃并[2，3-d]咪唑啉-2-酮双环结构，进而合成了天然产物slagenins A、B、和C的对映体。

Owing to the abroad application of Candida rugosa lipase in the resolution of racemic aminoacides, the prepared lipase was used in the resolution of phenylglycine and tert-leucine. Through the optimization of the reaction conditions, such as reaction substrate, pH, temperature, ion strength and additives, enantiomeric excesses for phenylglycine and tert-leucine reached 96% and 90.1%, respectively, enantiomeric ratio came up to 28. 9 and 15. 4, respectively.

鉴于该酶广泛应用于手性化合物的拆分研究，本论文中选用了两种手性氨基酸作为拆分对象，通过对反应体系中一系列条件的优化，包括底物、pH、温度、离子强度以及添加物的使用，苯甘氨酸和叔亮氨酸的对映体过量值分别达到96%和90.1%，对映催选择率分别达到28.9和15.4。

Results indicated that the-enantiomer showed significantly higher activity on cucumber and sorghum fresh weight inhibition than that of the-enantiomer, and also higher than that of the racemate at the same rate.

结果表明，单一左右旋对映体和等量的外消旋处理的高梁和黄瓜鲜重抑制作用差异显著，右旋体活性明显高于左旋体，也明显高于等量的外消旋体。

In the case of racemate 2, better resolution was obtained when using 2-propanol as modifier in the place of methanol and ethanol, while for racemate 1, methanol provided the best performance. Both retention and resolution decreased with increase in pressure.

结果表明对映体的保留因子均随着改性剂含量的增加而显著下降，当改性剂含量大于10%时，保留因子的下降趋势变缓；分离帕罗酮酯时，异丙醇作改性剂的分离度和分离因子均最大，分离帕罗醇对映体时，甲醇是最佳的改性剂。

The effects of racemate initial concentration, volume ratio of surfactant to organic solvent, pH value in internal or external phase, pH gradient from external to internal phase, ligand metallicion and system temperature on the performances of chiral separation were discussed.

摘 要：研究在含有Cu2+和N-n-十二烷基-L-脯氨酸手性配体的乳状液膜体系中手性萃取分离氧氟沙星对映体的效果，以及外消旋体的初始浓度、表面活性剂与有机溶剂的体积配比、内外水相pH值、从外水相到内水相pH值梯度变化以及配位金属离子与体系温度对液膜手性分离性能的影响。

Objective To develop a RP-HPLC method for the enantiomeric separation of indapamide on a new chiral column CHIRALCEL OD-RHcellulose tris(3,5-dimethylphenylcarbamatecoated on a5μm silica-gel substratefor pharmaceutical study of indapamide.Methods To obtain optimistic method for the enantiomeric separation of indapamide,the inferences of the composition of mobile phase,the flow rate and the temperature on the enantiomer retentivity and selectivity were examined and discussed.

目的采 用新型反相手性色谱柱CHIRALCEL OD-RH(纤维素3，5-二甲基苯基氨基甲酸酯涂敷在5μm硅胶上)，建立吲达帕胺对映体的反相高效液相色谱拆分方法，为研究吲达帕胺手性对映体药代动力学提供基础。

A general theme of these processes is the combination of an enantioselective enzyme with a chemical reagent,the latter being used either to racemise the unreactive enantiomer or alterna...

在催化反应过程中，一般都是对映体选择性酶与化学试剂的相结合，化学试剂一般常用于催化非活性对映体发生去消旋反应或是回收去消旋化过程中的中间体。

Where ee〓 is the enantiomeric excess of the initial antipodal mixture, ee'is the enantiomeric excess of the recycled product fraction.

其中ee〓、ee'分别为初始对映体混合物和产物的对映体过量值。

Separation of racemic mixtures of benzyl glycidyl ether was achieved with HPLC by using Chiralcel OD as chiral stationary phase and hexane/2-propanol mixture of different ratios as eluents.

在 Chiralcel OD多糖类手性固定相上，以各种不同配比的正己烷-异丙醇为洗脱剂，对苄基缩水甘油醚的外消旋体进行对映体拆分，考察了不同洗脱剂配比、柱温和流速对分离度和出峰时间的影响。

Resolution and preparation of ethofumesate enantiomers were achieved under the optimal semi-preparation conditions. The chemical structure of two elutes were identified by GC-MS, the optical property and the eluting order were determined by using the Circular Dichroism detector and polarimeter.

在优化的半制备色谱条件下，完成了乙氧呋草黄对映体的拆分、收集和制备，两个组分的化学结构经GC-MS确证，光学性质和流出顺序用圆二色检测器和旋光仪进行测定，获得了光学纯度超过97%的左旋和右旋对映体。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。