对映异构的

For the first time, enantiomers of C2-symmetric 1,1 -spirobiindane-7,7'-diol were resolved with crude menthyl chloroformate by phase-transfer catalysis in the presence of tetrabutylammonium bromide. The reaction was carried out at 0℃-rt. The diastereomers of SPINOL bis-menthyl carbonate can be separated by simple crystallization using alcohol. The hydrolysis of the diastereomers was carried out via aqueous NaOH/EtOH solution.

首次通过相转移催化的方法对螺双二氢茚二酚进行了有效的拆分，用L--氯甲酸薄荷醇酯做拆分剂，以四丁基溴化铵为催化剂在0℃-室温下进行酯化反应生成非对映体衍生物，以乙醇作溶剂，通过重结晶的方法分离衍生物，在水-乙醇混合溶剂条件下，用强碱NaOH或KOH分别水解，制得相应的光学纯度大于99%ee的两个异构体SPINOL，其中总收率：--SPINOL，78.2%；--SPINOL，80.6%。

Polyethylene glycol ethers of alkyl alcohols having the general formula CH3(CH2)xCH2(OCH2CH2)nOH wherein x is 8 to 20 (of which ceteareth-20, steareth-20 and steareth-100 are preferred), poloxamer 185, poloxamer 407, N,N-dimethyl dodecylamine N-oxide, and mixtures thereof, are employed to increase follicular delivery and/or follicular residence time of certain water soluble ornithine decarboxylase inhibitors of which 2-2,5-diamino pentanoic acid and its pharmaceutically acceptable salts, hydrates, optical enantiomers and racemic mixture are preferred.

使用通式为CH3(CH2)xCH2(OCH2CH2)nOH的烷基醇的聚乙二醇醚，其中x为8-20(其中鲸蜡硬脂醇醚-20、硬脂醇醚-20和硬脂醇醚-100是优选的)、poloxamer 185、poloxamer 407、N，N-二甲基十二烷胺N-氧化物及其混合物来提高某些水溶性的鸟氨酸脱羧酶抑制剂的毛囊传输和/或毛囊停留时间，优选的抑制剂是2--2，5-二氨基戊酸及其药学上可接受的盐、水合物、光学对映异构体及外消旋混合物。

Nevertheless, the yield of pinacol was also strongly affected by the steric environment surrounding the carbonyl group. The pinacol coupling of aromatic aldehydes has been achieved with high yields under such a condition. However, the diastereose-lectivities of pinacols were not satisfying. Unfortunately, the ketones and most aliphatic aldehydes appeared inert under the same reaction conditions.

然而， 呐偶合反应的产率受到羰基周围环境的立体位阻影响较大，在此条件下，锌粉能有效地促进芳香族醛类化合物进行水相呐偶合反应，得到的呐醇产率高，但非对映异构体选择性差，而脂肪族醛类化合物得到的呐醇产率较低，在同样的条件下，酮类化合物不能顺利进行呐偶合反应。

The effect of silicon atom in substrate on the reaction rate and the stereoselectivity of enzymatic reactions was revealed by comparison of horse liver alcohol dehydrogenase-catalyzed stereoselective dehydrogenation of the three isomers of acetyltrimethyl propanone and their carbon analogues in aqueous/organic biphasic systems.

本项目通过对比在水－有机溶剂两相系统中，马肝醇脱氢酶催化三甲基硅烷丙酮的三个异构体及其碳类似物的光学选择性脱氢反应，揭示了底物中的硅原子对酶反应速度、立体选择性的影响规律，成功地合成了高对映体纯度的手性有机硅醇，并实现了辅酶的再生。

PK values of 3-ethoxy-N-desmethyldiazepam (3-EtO-NDZ) in ethanol and acetonitrile containing various concentrations of sulfuric acid, determined by spectrophotometry and spectropolarimetry, were found to be 3.4 and 0.63 respectively. Temperature dependent racemization of enantiomeric 3-EtO-NDZ in ethanol containing various acid concentrations was studied by monitoring changes of ellipticity at 365 nm as a function of time on a spectropolarimeter.

3-乙氧基－N去甲基安定（3-EtO-NDZ；diazepam=安定）在含不同硫酸浓度的乙醇和乙腈中的pK值用光谱法和旋光光谱法作了测定，其结果分别为3.4和0.63.3-EtO-NDZ之对映异构体在含各种不同酸浓度的乙醇中与温度相关的消旋过程，用旋光光谱仪选择其圆二色谱在365nm波长处强度的改变为时间函数的方法作了测定。

This Sm-catalyzed reaction firstly efficiently realized the catalytic cycle in the tandem rearrangement/reduction reaction of α-hydroxy epoxides, and moreover the diastereoselective amplification could be distinctly observed when two C1 epimers in substrate were subjected to this catalytic tandem reaction.

该催化的多功能串联反应，高度非对映选择性地一步控制了含有季碳的三个相邻立体中心，有效地构建了&2-季碳1，3-二醇&结构单元，首次实现了此类重排—还原过程的催化循环，其中对于两个C1位的差向异构体底物，此反应具有明显的非对映选择性放大特点。

In recent years, optically active polymers have attracted much attention because of their unique functions such as molecular recognition, optical resolution for racemates and catalytic activity in asymmetric transformations as well.

近年来，光学活性聚合物的合成与结构—性能研究深受国内外学者的高度关注，这是由于这些合成材料具有潜在的应用前景，如：光学活性聚合物可应用于外消旋混合物的对映异构体分离，即光学拆分过程；不对称吸附、手性诱导及许多有机化学反应过程中的不对称催化。

The 5-cm short CD-based column exhibited rapid separation ability to the above β-blocker drugs within 5 min, which indicated that the separation has high efficiency.

所制备的短柱具有快速分离的特点，在5 min内实现了上述5对手性药物对映异构体的分离，具有较高的分离效率。

They weren't aggressive, but I yelled and threw a rock in their direction to get them off the trail and away from me, just in case.

他们没有侵略性，但我大喊，并在他们的方向扔石头让他们过的线索，远离我，以防万一。

In slot 2 in your bag put wrapping paper, quantity does not matter in this case.

在你的书包里槽2把包装纸、数量无关紧要。