关键词： 不对称合成   路线   蛇麻烯   含氧   衍生物  

关键词： 立体化学   对映选择性   不对称合成   精细化工  

摘要： 简单介绍了不对称合成的基本原理,叙述了近年来不对称合成方法的某些进展及在精细化工中的一些重要应用。

关键词： 手性试剂   酶催化活性   合成子   光学活性   不对称合成   立体选择反应   对映体   旋光   醇脱氢酶   磷酸醋  

摘要： 综述了酶在有机合成中的应用。

关键词： 手性   对映异构体选择性   有机硅   醛   高烯丙基醇   昆虫激素  

摘要： 由(-)-β- 蒎烯合成了(-)-二甲基烯丙基(7,7-二甲基降蒎烷基)硅烷(1)。1和一系列醛反应可以得到手性高烯丙基醇(5)。反应有一定的对映异构体选择性。产物的构型与使用的催化剂有关。应用此反应合成了有光学活性的4-辛基-γ-内酯。

关键词： 不对称   化合物   缩酮   手性助剂   芳基   取代基   光学活性   烷酸   酒石酸   羟基羧酸  

摘要： 2-芳基烷酸类化合物在解热、镇痛药中占有重要地位,它的分子中有一不对称中心,因此存在一对对映体。对于某些化合物,其对映体之一具有较高的生物活性,往往需要得到光学纯产物。通常以光学活性的胺进行拆分。其缺点在于非活性对映体的消旋、拆分剂的回收及操作条件的控制等较为繁复,因此该类化合物的不对称合成即成为研究的目标之一,有不少精采的报道。新近发展的几种以α-易离去基团取代的烷基芳基缩酮经芳基1,2-迁移合成2-芳基烷酸的方法,由于经济、简便、选择性高,已

关键词： D-苯丙氨酸   不对称合成   手性相转移催化剂  

摘要： 目前,氨基酸不对称合成方法甚多,但是使用手性相转移催化剂未见有报道。本文报道在同位素标记氨基酸不对称合成研究中,用非标记甘氨酸进行模型试验的初步结果:使用(-)-氯化-N-苄基辛可尼丁鎓作催化剂,可获得近90%光学纯度的 D-苯丙氨酸,化学产率61.6%。

摘要： This thesis is concerned with the asymmetric synthesis of cyclopropyl derivatives via the use of chiral iron acyl complexes of the type ($\eta\sp5$-C$\sb5$H$\sb5$)Fe(CO)(PPh$\sb3$)(COCH=CR$\sp\prime$R). Chapter 1 reviews previous routes to optically active cyclopropyl derivatives and reviews the use of the chiral auxiliary ($\eta\sp5$-C$\sb5$H$\sb5$)Fe(CO)(PPh$\sb3$) for asymmetric synthesis. Chapter 2 describes the synthesis of the complexes ($\eta\sp5$-C$\sb5$H$\sb5$)Fe(CO)(PPh$\sb3$)(COCH=CRR$\sp\prime$) and presents a conformational analysis of the $\alpha$,$\beta$-unsaturated acyl ligand. Chapter 3 describes the diastereoselective synthesis of cis-substituted cyclopropyl complexes via the reaction of Z-$\alpha$,$\beta$-unsaturated iron acyl complexes with electrophilic alkylidene species. Decomplexation, to give the corresponding cyclopropyl esters, occurred without epimerisation of the cyclopropane ring. By the use of homochiral iron acyl complexes the enantioselective synthesis of cyclopropyl derivatives was achieved. Section A describes methylene addition and Section B isopropylidene addition reactions. Section C describes attempts to synthesise pyrethroid insecticide precursors which occurred with good diastereoselectivity but poor regioselectivity. Section D describes electrophilic ethylidene addition reactions in which the chiral auxiliary exerts good stereochemical control over three new chiral centres. Chapter 4 describes the diastereoselective synthesis of trans-substituted cyclopropyl complexes via the reaction of E-$\alpha$,$\beta$-unsaturated iron acyl complexes with nucleophilic alkylidene transfer reagents. Section A describes methylene transfer reagents. Whilst $\alpha$-lithiosulphides and $\alpha$-lithiosulphoxides were of limited use, iodomethyllithium (generated in situ) resulted in highly diastereoselective syntheses of the cyclopropyl complexes. Decomplexation, to give the corresponding cyclopropyl esters, occurred without epimerisation of t

摘要： A study of alkylation, conjugation addition and cyclisation reactions of sulphoxides was carried out. Lithiation of 4-alkoxybutyl p-tolyl sulphoxides with lithium diisopropylamide and alkylation with methyl iodide and benzyl bromide gave very poor stereoselectivity, but use of the corresponding t-butyl derivatives led to a large increase in selectivity. Addition of lithiated phenethyl t-butyl sulphoxides to methyl acrylate and methyl crotonate at low temperature, gave the conjugation addition products in good yields. Moreover, the stereoselectivity was high and an x-ray crystal structure determination was used to determine the relative configuration of the adduct derived from methyl crotonate. Attempted cyclisation of the methyl acrylate conjugation addition product, and the alcohol obtained by reduction with lithium aluminium hydride, by reduction of the sulphoxides, S-methylation of the resulting sulphides and intramolecular displacements of the sulphonium salts could not be achieved since S-alkylations using reagents such as methyl triflate and trimethyloxonium tetrafluoroborate were not successful under various conditions. However, reaction of the methyl acrylate adducts with iodotrimethylsilane resulted in the reduction of the sulphoxides, cleavage of the t-butyl sulphides and cyclisation leading to a cyclic thioester. The corresponding alcohol yielded a tetrahydrothiophene and this is a new method for the formation of this ring system.

关键词： Aspartame   天冬   二肽   盐酸水解   分离制   Fischer   丙二酸   糖质   不对称合成   乙酞胺  

摘要： 苯丙氨酸是1879年Scholze和Barbieri发现的。并且首先从羽扁豆中分离出来。接着1901年Fischer用盐酸水解酪元(Casein)分离制得苯丙氨酸。以后苯丙氨酸的提取、合成和发酵等制备方法陆续出现,并且不断改进和创新。苯丙氨酸纯品白色粉末结晶。呈苦味,