对映体

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。

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。

The ligand of the chiral Schiff base and acetylacetone vanadium are subjected to complexation in situ, hydrogen peroxide is taken as an oxidant, aryl alkyl thioether asymmetric oxidation reaction is catalyzed in a toluene or dichloromethane solution under low temperature or room temperature, enantioselectivity of chiral sulphoxide is 72 percent to 95 percent ee, and yield is 42 percent to 83 percent.

将上述手性西佛碱配体与乙酰丙酮氧钒原位络合，采用双氧水为氧化剂，在甲苯或二氯甲烷溶液中低温至室温下催化芳基烷基硫醚不对称氧化反应，手性亚砜的对映选择性为72％-95％ee，产率为42％-83％。

Meso-Tetrakis(2,6-dichlorophenyl)porphyrinmanganese chloride and carbonyl ruthenium meso-tetrakis(2,6-dichlorophenyl)porphyrin were prepared and used to catalyze the diastereoselective epoxidation and amidation of 3β-substituted Δ 5-steroid derivatives.

研究了 5 ，10 ，15 ，2 0 (2 ，6 二氯苯基)卟啉锰及其钌配合物这类非手性的催化剂催化3β取代的Δ5 甾体衍生物的非对映选择性环氧化及酰胺化反应。

Part Ⅰ The Research of Chiral Phosphorus Catalysts in the Enantioselective Borane Reduction of Prochiral Ketones ABSTRACT In this paper, the preparation of varied types of chiral phosphorus ligands and their applications as catalysts in the asymmetric borane reduction of prochiral ketones were investigated.

第一部分对映选择的潜手性酮的硼烷还原反应中手性磷催化剂的研究本文研究了多种不同类型的手性磷配体催化剂的合成及其在酮的不对称硼烷还原反应中的应用。

Compared with tartrates of low molecular weight, although the workup was simplified, the catalytic activity and enantioselectivity aren't acceptable.

的对映选择性，但这种高催化活性仅存在于个别底物的环氧化中，并且配体的用量较大，一般都在50％mol。

Synthesis of such compounds from nonchiral materials results in equal numbers of the enantiomers, racemates.

使用非手性物料合成此类化合物导致等量的对映异构体和外消旋物。

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。

Finally, we demonstrate the transformation of β-hydroxy nitriles to a variety of diastereomerically pure and highly functionalized acyclic and heterocyclic γ-amino alcohol derivatives.

最后， 本文介绍了由β-羟基腈向各种纯非对映异构体，多功能性的开环和杂环γ-氨基醇衍生物的转化反应。

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。

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。