关键词： 手性化合物   不对称合成   膦配体  

摘要： 不对称催化是由潜手性反应物合成光活性化合物的有效途径,α,β-不饱和氨基酸的氢化立体选择性已达90％以上,L-Dopa的工业化生产则标志着不对称催化氢化开始走向实际应用。高选择性的催化剂一般是一价铑的手性双膦配体络合物,其中DIOP[2,3-O-异丙叉-

关键词： 羰基   不对称合成   加成反应  

关键词： 手性受载试剂   不对称合成  

摘要： 各种手性受载试剂的制备及其在不对称反应中的应用,例如加成反应、还原反应、甲酰化反应、氨基酸的合成、氧化偶合反应和环氧化反应等。其中大多数反应的对映超量都较高。

关键词： 丙氨酸   相转移催化   双不对称诱导  

摘要： 氨基酸的不对称合成是近年来研究热点之一,双不对称合成新设想为高光学纯度物质的合成提供了一条有益的思路。本文考察在手性相转移催化条件下,邻苯二甲酰亚胺钾与手性α-溴代丙酸龙脑酯的Gabriel反应制取光学活性丙氨酸,观察到显著的双不对称诱导效应。 仪器为Perkin-Elmer 241MC型旋光仪、PE240-C型元素分析仪。邻苯二甲酰亚胺钾按文献[3]制备;α-溴代丙酸乙酯为上海试剂总厂产品,(一)-龙脑为贵州罗甸制药厂产品,[αj_D^(25)=—37.2,(C5,乙醇);α-溴代丙酸龙脑酯根据文献制备并经过元素分析和光谱鉴定。(一)

关键词： Baker酵母   不对称合成   光学活性  

摘要： Baker酵母以独特的方式在制备高光学活性手性化合物中起着重要作用。本文重点介绍 Baker 酵母在合成光学活性羟基化合物、硫化物、昆虫性信息素等方面的应用及其特点。参考文献44篇。

关键词： .sulfoxides   active site   fish labelling   reagent   steric   sulfides   Molecular recognition   asymmetric oxidation   oxaziridine   selenoxides   Labelling Regulations Northern  

摘要： The development of reagents for the asymmetric oxidation of sulfides to sulfoxides with high stereoselectivities is problematic because these substrates are nonfunctionalized. Nevertheless N-(phenylsulfonyl)(3,3-dichlorocamphoryl)oxaziridine (4) exhibits remarkably high and predictable ee's for the asymmetric oxidation of sulfides to sulfoxides (66->95% ee), selenides to selenoxides (90->95% ee) and sulfenimines to sulfinimines (85-91% ee). While steric effects are primarily responsible for the molecular recognition, an important electronic component is operational for those sulfides having an aryl group directly attached to the sulfur atom. The high ee's associate with this reagent are a consequence of the presence of complementary vacant regions and a molecular cleft or grove on the active site surface.

关键词： .optically   Food Supplements Wales  

摘要： The reaction of chiral vinyl sulfoxides with dichloroketene to yield optically active gamma-butyrolactones provides the basis for enantioselective syntheses of heterocyclic natural products. In particular, 2-alkylsulfinylindoles are transformed into butyrolactones that serve as precursors to the physostigmine alkaloids. The total synthesis of physostigmine in optically active form has revealed the importance of the size of alkyl group of the sulfoxide in the 3,3-sigmatropic rearrangement leading to the chiral butyrolactone. In addition, an efficient synthesis of optically active benzohydrofuran lactones which are precursors to the aflatoxins is described.