关键词： 活性聚合物   手性   不对称诱导   合成  

摘要： 本文介绍了活性聚合物的特点、合成方法及其在不对称合成中用作相转移催化剂、外消旋体拆分介质和不对称诱导反应手性促进剂等方面的发展近况。

关键词： 不对称合成   Michael反应   共轭加成  

摘要： 本文综述了不对称 Michael 加成反应的某些应用和进展,并分别讨论了各种不同类型的手性 Michael 加成反应。

关键词： 钛试剂   RTiX3   反应选择性   羰基化合物   醛酮   有机金属   不对称诱导   对映体过量   不对称合成   亲核性  

摘要： RMgX、RLi和RZnX等有机金属试剂在合成中的广泛应用已为人们熟知,由于这些试剂碱性强活性高,往往不适于某些醛酮的加成,且反应选择性不太理想。近十年来,Seebach和Reetz等人深入研究了RTiX₃类型有机钛试剂。在RTiX₃中,R为烃基、OR、OAr等,x可为卤素、OR、NR₂¹ 等不同基团。通过对配体X的改变,可以对电子因素和空间因素两个方面进行广泛的调节,从而使RTiX₃试剂在醛酮的加成反应中具有高度的化学选择性、对映选择性和立体选择性。所以,RTiX₃试剂现已成为有机合成中的有力工具。

关键词： α-甲基   α-氨基酸   卡宾   不对称合成   相转移催化  

摘要： 本文报道了以N—苄基氯化辛可宁为手性催化剂,由相转移卡宾法来不对称合成α—甲基—α—氨基酸.探讨反应条件对化学产率和光学收率的影响.

关键词： .asymmetric synthesis   asymmetric hydroboration   allylboration   organoboranes   asymmetric reduction   purities   crotylboration   boron approach  

摘要： The unique chemistry of organoboranes has made possible a three-pronged approach to asymmetric synthesis: 1) asymmetric hydroboration, 2) asymmetric reduction, and 3) asymmetric allyl- and crotylboration. Consequently, boron chemistry makes possible not only a uniquely general synthesis of pure enantiomers (with purities approaching 100% ee) as well as more complex stereoisomers by processes that are simple and broadly applicable. Boron derived reagents have proven to be exceptionally versatile for the asymmetric reduction of the carbonyl group in a variety of derivatives to give products of optical purities approaching 100% ee. Finally, the synthesis of chiral organoboranes containing allyl, crotyl and related groups attached to boron is providing a highly valuable synthesis via allylboration of stereoisomers in purities approaching 100% ee. It is evident that boron chemistry is providing major new routes for asymmetric synthesis in organic chemistry.

关键词： .asymmetric synthesis   stereospecific   deuterium   lithio   tin compounds   dichloromethyl   tertiary alcohols   diastereoselection   pinanediol   diastereomeric ratio   Cp symmetry   chloro boronic ester  

摘要： The reaction of chiral diol boronic esters with (dichloromethyl)lithium to form diol alpha-chloro boronic esters in high diastereomeric purity has been improved by the use of diols of C2 symmetry. Reaction of the resulting alpha-chloro boronic esters with alkyl Grignard reagents provides a further kinetic resolution in which the minor isomer is not converted to diastereomer but to an air-sensitive borinic ester. The final diastereomeric ratio can exceed 1000:1, and a diastereomeric pair of insect pheromones has been synthesized in unusually high purity. Other recent applications of alpha-chloro boronic ester chemistry in asymmetric synthesis will also be discussed. Diol boronic esters of C2 symmetry are useful in the conversion of alpha-chloro boronic esters via alpha-alkoxy tin compounds to alpha-lithio ethers, which in turn can be coupled to alpha-chloro boronic esters to provide a stereospecific convergent coupling of two chiral carbon chains. New applications of the older pinanediol ester technology have also been explored. These include syntheses of phenylalanine and of glycerol bearing stereospecific deuterium labels. Preparations of chiral tertiary alcohols have given useful stereoselectivity with some structures and not with others. A supplementary discovery is that solvent free dichloroborane can be generated from boron trichloride and trialkylsilanes and is an efficient hydroborating agent.

关键词： 樟脑   衍生物   不对称合成   手性助剂  

摘要： 介绍了樟脑及其衍生物在不对称还原反应、加成反应、烷基化反应、Diels-Alder 反应、氧化反应和卤化反应中的应用。同时还列举了樟脑及其衍生物在不对称合成中用作手性试剂和手性催化剂的一些例子。

关键词： 不对称合成   樟脑   亚胺   烷基化  

摘要： 目前,不对称合成光学活性化合物取得了较大进展,不对称合成α-氨基酸、β-氨基醇、α-取代苄胺的报道很多。但是,不对称合成生物碱类物质——α-取代氨甲基吡啶类化合物还未见文献报道,而此类化合物有潜在的应用前景。为此,我们以(+)