查询词典 chiral

With L-DOPA as the starting chiral phenylalanine derivatives, construction of the skeleton of Phthalascidin was studied. Firstly, starting from L-DOPA and 3,4-dimethoxyphenylalanine, an amide 〓 was obtained, and a modeling cyclization reaction was carried out but failed to give the anticipated product.

二、对由苯丙氨酸甲酯衍生物通过Bischler-Napieralski反应合成四氢异喹啉—3—甲酯进行了研究，通过研究首次发现，生成苄基噁唑的反应是正常的B-N反应的竞争性反应，并从机理上给予了解释，所得出的结论具有一定的规律性，在杂环的合成方面具有一定的应用价值。

The synthesis of the pentacyclic skeleton of Et-743 and the construction of the five chiral centers thereof.1. The core pentacyclic skeleton of phthalascidin was constructed with L-dopa as the starting material via thirteen steps. First, two basic synthons, the C-1 functionalized tetrahydroisoquinoline compounds 8 and N-protected Z-dopa derivative 9, were prepared from L-dopa. They were coupled via amide bond to form the dipeptide compounds 10, which were the first key intermediates. Then the primary hydroxyl groups were transformed into the corresponding amino aldehydes 11 via Swern oxidation. Followed by the intramolecular Pictet-Spengler cyclization, the pentacyclic compounds 12 were synthesized.

五环骨架的构建及五个正确手性中心的确立：1.1我们以L-多巴为起始原料，经过多步官能团保护和转化合成了基本结构单元8然后和苯丙氨酸衍生物9，通过缩合反应生成酰胺中间体10，经Swern氧化得到醛化合物11，然后再次利用分子内改良的Pictet-Spengler反应一步构建c，d两环，得到五环骨架化合物12，最后，实现了21-位羰基向氰基的转化，得到了C-1位官能化的化合物14，化合物14不但具有和Et-743一致的五环骨架，而且分子中五个手性中心立体构型也与其完全相同：其中，3，位和13，位的手性中心由原料L-多巴带入，而1，位，11，位和21，位手性中心则通过不对称诱导而确立。

In using DGF method, the first thing is to obtain the proper form of certain area. But the DGFs obtained now are all in achiral medium. So people are eager to know DGFs in spectral domain and space domain of chiral medium.

用解析的方法求解电磁场的边值问题主要依靠建立在经典电磁场理论基础上的并矢格林函数方法，应用DGF方法首先要找出适用于相应区域中的DGF形式，而现有的DGF形式都是基于非旋波媒质情形。

Because of their strong nucleophility of NHCs, the asymmetric Staudinger reaction between ketenes and imines catalyzed by chiral NHC was achieved, gave -lactams with excellent enantioselectivities.

中文摘要我们组利用氮杂环卡宾的亲核性，成功地实现了氮杂环卡宾催化的烯酮与亚胺的Staudinger反应。

In the last part, the study of controlling the stereochemistry of the newly formed chiral centers was not successful.

在第四部分，关於控制立体化学的相关研究方面，均无法得到好的结果。

Many chiral drugs may differ in their pharmacological activities due to the difference of stereochemistry.

许多药物对映体由于其空间结构的差异，导致其药理、药效上有很大的不同。

In addition to this,we discussed the stereochemistry in the synthesis of polyhydroxyα-amino acid based on chiral tert-butanesulfinyl amide.

除此之外，我们还系统讨论了基于叔丁基亚磺酰胺的多羟基取代α-氨基酸合成方法中的立体化学问题。

Company offers clients customized services, according to client provided by the molecular structural formula, for a variety of customized medicine, pesticide intermediates, organic reagents, chiral reagents and other organic chemical products, customized by the quantity of several milligrams to several tons.

公司提供客户定制服务，根据客户所提供的分子结构式，为客户定制各种医药、农药中间体、有机试剂、手性试剂等各种有机化工产品，定制数量可由几毫克到数吨。

Four new chiral sulfonamide alcohol s were synthesized from camphor and L-phenylalanine and their application to the enantioselective addition of diethylzinc to benzaldehyde was described.

由天然樟脑和-苯丙氨酸合成了4个新的手性磺酰胺醇，并对其在二乙基锌对苯甲醛的不对称加成中的催化性能进行了研究。

Four new chiral sulfonamide alcohols were synthesized from camphor and L-phenylalanine and their application to the enantioselective addition of diethylzinc to benzaldehyde was described.

由天然樟脑和-苯丙氨酸合成了4个新的手性磺酰胺醇，并对其在二乙基锌对苯甲醛的不对称加成中的催化性能进行了研究。

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％。