中间体

Lactonization of 32 swiftly took place under basic condition, and the first four-ring intermediate 53 was gained.

以动力学烯醇化-氧化的方法，在18的〓位引入了〓羟基，解决了构成1，4-内酯环的相对立体化学问题。32在碱性条件下，顺利完成了1，4-内酯环的构筑，首次获得了四环中间体53。

Chiral centers of C5 and C8 are directly constructed in the key step of the diastereoselective propargylation from D--tartrate. The methylation and subsequent methoxycarbonylation result in desymmetrization of the terminal dialkynes. The α,β-unsaturated δ-lactone is synthesized after partial hydrogenation and lactonization.

由非天然酒石酸出发，利用双向非对映选择性的炔丙基化反应，在一步反应中同时构建C5和C8手性中心；然后通过末端炔基的甲基化、甲酯基化，延长碳链并对分子去对称化；内酯化得到关键中间体α，β-不饱和六元内酯，再经多步反应转化得到8-epi--Boronolide。

As a new chemical platform and a pharmaceutical intermediates, Levulinic acid uses extensively as an important chemical raw materials.

作为制备多种化工产品的新型平台化合物和医药中间体，乙酰丙酸用途广泛，是重要的化工原料。

A Michael addition of dimethyl malonate and 2-pentyl-cyclopentenone could conduct a precursor which used for preparing aim compound by a selective decarboxylation.

中间体化合物2-戊基环戊烯酮在一定条件下经Michael加成和选择性脱羧反应合成目标化合物。

Whereas, at the second stage H-transfer from indole to malonate occurs with the formation of the new C—H bond, the energy barriers calculated for this step are 99.2 and 115.1 kJ/mol for the R - and S -configuration product, respectively.

其中第一阶段由复合物经过渡态TS1生成中间体IM，是C—C键的形成阶段，该阶段的活化能垒较后一阶段要大，是该反应的决速步骤；第二阶段由IM经过渡态TS2生成产物，完成H迁移和C—H键的形成。

Among them, BRS1 with mercapto alkylchlorine substituting group, which can be used as intermediate for the synthesisof new BR derivatives.

其中一种(BRS1)为末端氯代的化合物，可以作为中间体用于进一步的合成中。

2 mercapto 5 methoxybenzimidazole,a key intermediate for the synthesis of omeperazole,was synthesized in 80% yield over two steps.

目的 合成奥美拉唑中间体2 巯基 5 甲氧基 1H 苯并咪唑。

In present paper, the progress of quinoline derivatives in synthesis and application are summarized first, then according to a lot of literature, designed the synthetic route for 8 derivatives of 6-AQ. They are 4-chloro-6-AQ, 5- chloro -6-AQ, 5-methoxyl-6-AQ, 7- chloro -6-AQ, 8- chloro -6-AQ, 8-bromo-6-AQ, 8-methyl-6-AQ and 8- methoxyl -6-AQ. All the products were obtained by reduction of its corresponding 6-nitroquinoline.

在对过往文献大量查阅的基础上，本文首先综述了喹啉及其衍生物的性质、合成方法及应用研究进展，并通过对文献报道方法的优化和改进成功地设计合成了4-氯-6-AQ、5-氯-6-AQ、5-甲氧基-6-AQ、7-氯-6-AQ、8-氯-6-AQ、8-溴-6-AQ、8-甲基-6-AQ和8-甲氧基-6-AQ等8种6-AQ的衍生物作为研究新型抗疟疾药物的中间体。

In this paper, the structures of methylglyoxal and 1,1-dimethoxy-2-propanone are identified by GC-MS, NMR and the standard samples. The reaction conditions of catalyst oxidation and acetalation according to reaction mechanisms are discussed.

本文运用质谱、核磁和标样确定了中间体丙酮醛及其产物1，1-二甲氧基丙酮的结构，并结合反应机理对催化氧化和醛保护的反应工艺条件进行了探索。

Using the chemical reaction route selection method proposed by the authors, a reaction route of using commercial methylglyoxal as the starting material to produce Furaneol was chosen.

今采用作者提出的化学反应路径选择因子对呋喃酮的合成方法进行计算比较，确定了以丙酮醛为原料，通过偶联反应合成中间体苏式3，4-二羟基-2，5-己二酮，再由成环反应制备产物呋喃酮的合成路线。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。