查询词典 reaction ring

They can exist in a chain form or in a ring formed by reaction of the ketone or aldehyde group with an – OH group on one of the carbons at the other end of the chain.

它们有链式和环式。环式结构的形成是酮基或醛基与碳链另一端的羟基发生反应而相结合。

Constituting dicycle; 2. region selectively reducing six-membered ring ketocarbonyl radical; 3. introducing 7alpha-hydroxy group; 4. Aldol reaction to introduce side chain and obtain 8alpha-hydroxy group; 5. oxidizing the position 7 hydroxy group into ketone; 6. turning the configuration of the position 7 hydroxy group; 7. glycosidating the position 7 hydroxy group; and 8. eliminating protecting group to obtain the target compound.

该方法包括如下步骤：(1)双环的构建；(2)区域选择性还原六元环酮羰基；(3)7α-羟基的引入；(4)Aldol反应引入侧链，同时得到8α-羟基；(5)7位羟基氧化为酮；(6)7位羟基构型的翻转；(7)7位羟基的糖苷化；(8)脱除保护基得到目标化合物。

This article reviews the ring opening reaction of five membered nitrogen containing heterocyclic compounds.

综述了近年来各种五元氮杂环的开环反应及其在有机合成中的应用。

In the coupling reaction of 4 with 2-methyl-1-buten-3-yne the four- membered ring ligand is transferred to enyne to give the substituted eta3-butadienyl complex 5 containing the cyclobutenonyl group.

在4与2-甲基-3-炔-1-丁烯进行偶合反应后，四环结构仍然稳固存在，并转移到烯缺上形成一个含有四环结构的错合物5。

Therefore, studies and applications of the ring-opening reaction of 1, 3-dithiolancycolpentyl moiety should be a valuable research project.

因此，α-羰基环二硫缩烯酮的1， 3-二硫戊环的开环反应及其在合成中的应用研究是一重要的研究课题。

Goal compound synthesis namely: Take the vanillic acid as outset raw material, obtains 4- hydroxyl - 3- anisole methyl formate with the methyl alcohol reflux conditions, then after the etherification, the nitration, the return to original state, the ring closure response obtains 6- methoxy - 7- animal pen oxygen radical kui zuo lin - 4- alkone, then passes through the chlorination, the substitution aniline, to escape responses again and so on animal pen oxygen radical, etherification to obtain the goal compound; The goal compound and the diethylamine had the amine substitution reaction to obtain TM1, namely 4- benzene amino - 6- methoxy - 7- [2- hydroxyl - 3-(N, N- two ethyl aminos) third oxygen radical] kui zuo lin; Through zuo has the etherification with the Austria niter to respond obtains TM2, namely 4- benzene amino - 6- methoxy - 7- [2- hydroxyl - 3-(2- methyl - 5- nitryl imidazole) third oxygen radical] kui zuo lin.

目标化合物的合成即：以香草酸为起始原料，与甲醇回流条件下得到4-羟基-3-甲氧基苯甲酸甲酯，然后经过醚化、硝化、还原、环合反应得到6-甲氧基-7-苄氧基喹唑啉-4-酮，然后再经氯化、取代苯胺、脱苄氧基、醚化等反应得到目标化合物；目标化合物与二乙胺发生胺取代反应得到了TM1，即4-苯氨基-6-甲氧基-7-[2-羟基-3-丙氧基]喹唑啉；通过与奥硝唑发生醚化反应得到TM2，即4-苯氨基-6-甲氧基-7-[2-羟基-3-(2-甲基-5-硝基咪唑)丙氧基]喹唑啉。

We described that the nitro group is a stronger electron withdrawing and meta activating characters than the imide group, the amino and hydroxy are both electron donating groups and had ortho, para activating characters. The methyl group might have a steric hindrance effect in this reaction. Our results indicated that methyl group at the ortho position of the amino group on the benzene ring, the steric hindrance effect became stronger.

另一方面，由产率上的结果来看，可以得知硝基为强力的拉电子基团，会减少邻位和对位胺基的电子密度比间位多；而氢氧基与胺基是供电子基团，会增加邻位和对位胺基的电子密度比间位多；甲基取代对反应则只有立体障碍的影响，而且与反应的氨基成邻位存在下影响最大。

A process for reducing nitryl with unstable guanyl on para-position of benzene ring into azyl features that active metal reacts on organic acid and solvent at ordinary temp. and pressure to reduce N-(2 or 3-M, 5 or 6-M',4-nitrophenyl)-N',N'-dimethyl acetamidine into N-(2 or 3-m, 5 or 6-M', 4-aminophenyl)-N',N'-dimethyl acetamidine, where M=H,-R,-OR,-COOR (R=H, C1-C6); and M'=H,-R,-OR,-COOR (R=H, C1-C6). Its advantages include reduced by-reaction and high reducting rate up to 80%-95%.

本发明是将苯环上对位带有不稳定脒基的硝基还原为氨基的方法，采用活泼金属，如：锌或锡，与有机酸和适当的溶剂，在常温、常压下发生反应，将N－（2或3－M，5或6－M＇，4－硝基苯基）－N＇，N＇－二甲基乙脒还原为N－（2或3－M，5或6－M＇，4－氨基苯基）－N＇，N＇－二甲基乙脒，其中M＝H，－R，－OR，－COOR（R＝H，C1－C6），M＇＝H，－R，－OR，－COOR（R＝H，C1－C6），减少了副反应，使还原收率达到80％以上，最高可达95％以上，更适用于工业化生产。

Syntheses of PPVs derivatives with alkoxyl as side-chain by the method of dehalogenating condensation reaction Those PPV derivatives, named poly (2-methoxy-5-alkoxyl) phenylene vinylene,containing alkoxyl on benzene ring, were placed on emphasis in this paper.

一。通过强碱诱导的去卤缩合法合成支链含不同烷氧基的PPV衍生物本文首先重点研究了支链中含不同链长烷氧取代基的PPV衍生物：聚(2-甲氧基-5-烷氧基)对苯乙炔。

So it may be extremely significant that using the simple effective Heck reaction to synthesis the complex compounds containing the pyrrole or the pyrrolidinone ring.

因此，利用简单高效的Heck反应合成含吡咯或吡咯酮环的复杂化合物将是非常有意义的工作。

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。