不对称

For example, using chiral tungsten 2'-pyridinyl alcoholate complex at 50 ℃, the ee value was increased from 54% to 78%.

在磷霉素的不对称合成研究方面只有Giordano等[4]是以顺丙烯膦酸为起始原料进行的。

The asymmetric aldol reaction is one of the most important methods of forming carbon-carbon bonds.

不对称羟醛缩合反应是有机合成中立体选择性地形成碳碳键的最重要方法之一。

Its zinc complex was applied in asymmetric direct aldol reaction of acetone and p-nitrobenzal...

设计合成了一种NOBIN衍生的手性配体，初步研究了该手性配体的双核锌配合物在对硝基苯甲醛和丙酮的不对称直接醇醛缩合反应中的催化应用，20℃和20mol％催化剂量下，获得了32.5％ee和72％收率的产物。

Synthesis of novel 4-long alkoxyl-L-prolines and their application in catalytic asymmetric direct aldol reaction.

一、研究了新型长链烷基脯氨酸的合成及其作为有机小分子催化剂催化的直接不对称Aldol反应 1。

The catalytic mechanism of prolinamide phenol on the direct aldol reaction was studied using quantum mechanics theory.

利用量子力学理论研究了脯氨酰胺酚类催化剂催化直接不对称Aldol反应的机理。

In order to examine the catalytic activity of the new catalysts, we have carried out the direct asymmetric Aldol reaction of tetrahydro-4H-thiopyran-4-one with aldehydes.

催化剂的基本结构单元如下：为了检验新型有机催化剂的催化活性，我们研究了硫代四氢吡喃酮和各种醛的直接不对称Aldol反应。

We found that when acetone was used as solvent, in the presence of TFA, cis-4-pyrrodin-1-yl-L-proline could catalyze the direct asymmetric aldol reaction between acetone and 4-nitrobenzaldehyde with 84% ee.

研究发现，该催化剂以丙酮为溶剂时，加入催化剂等当量的三氟乙酸可以较好的催化丙酮与对硝基苯甲醛之间的直接不对称Aldol反应，得到84%的ee值。

The catalytic effects of 1a and 1b on the intermolecular direct asymmetric aldol reaction were evaluated in organic solvents and in water respectively. The activity of 1a was higher than that of 1b.

研究了1a和1b分别在有机相和水中催化分子间直接不对称Aldol反应的性能，发现具有较长烷基链的1a比具有较短链的1b催化活性高。

The key reaction included Aldol condensation,CBS asymmetric reduction and Mitsnobu reaction.

合成过程中的关键反应为Aldol缩合，CBS不对称还原，Mitsnobu反应等。

The purpose of the above mentioned obligations is to relieve the asymmetric information, avoid moral hazard caused by the adhesive, aleatory and continuity nature of insurance contract.

上述义务的根本目的在于缓解双方的信息不对称，避免保险合同的附合性、射幸性以及连续性所带来的道德风险。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。