离去基团

通过改变溶剂的极性、离子性、离去基团的活性及反应温度等方法，对传统的Pedersen冠醚合成法进行了优化，使目标产物的最高产率达到71%以上。

The traditional synthesis of crown ether was optimized by changing polar and ionic properties of the solvent , activity of leaving group and temperature . The best yield can be over 71 % .

又以N-甲基咪唑为对象，合成了带有对羟基苯甲醇易离去基团的离子液受体。

And N-methyl-imidazole being target , we synthesized ionic liquid-acceptors with the easy leaving group p-methyl .

能生成相对稳定的正碳离子和离去基团的反应物容易发生SN1，中心碳原子空间阻碍小的反应物容易发生SN2。

Can generate is relatively stable carbon-left groups and the response of vulnerable SN1 , central carbon atom space hampered the response of small-prone SN2 .

分析了不同的离去基团和不同的保护基策略对糖肽合成的影响。

The factors which affect the results of glycopeptide synthesis were analyzed .

离去基团、非离去基团及中间体性质对取代苯甲酸苯酯氨解反应的影响

Influence of the Properties of Leaving Group , Non-leaving Group and Intermediate on the Aminolysis Reaction of Substituted Phenyl Benzoates

结果表明，一锅合成反应经历了含有两个离去基团中间体的形成和后续的两次消除过程。

The results showed one-pot procedure contained the formation of intermediate which borne two leaving groups and double elimination process of these two leaving groups .

在这对孤电子的立体电子效应作用下，促使重排基团带着一对电子从离去基团的反位上进行1,2&位移。

By the action of the stereoelectronic effect of this pair of unshared electrons , the migrating group with its a pair of bonding elections undergoes a 1,2-shift from the opposite position of the learing group .

磷酸酯及其酸酐在蛋白质的生物合成中起着十分重要的作用，它们充当了氨基酸的活化试剂和运输载体，当肽键形成后又作为离去基团离去。

Phosphate esters and anhydrides play important roles in the biosynthesis of proteins , they act as the activators and carriers of amino acids in the biochemical reactions , and go away as the leaving groups after the formation of peptide bond .

指出在频哪醇重排反应中，离去基团和迁移基团总是处在反式共平面位置，而迁移基团与它所在碳上的羟基氧上一对孤电子也处于反式共平面位置。

The characteristics of the reaction are that the learning group and the migrating group lie trans to each other and so are the migrating group and a pair of unshared electrons on oxygen of hydroxy on the carbon bonded with the migrating group .