关键词： 不对称合成   Darzens反应   手性氯乙酸酯   甲氧苯基  

摘要： 利用（－）－氯乙酸薄荷酯（１）和（－）－氯乙酸冰片酯（２）与对－甲氧基苯甲醛（３）进行不对称Ｄａｒｚｅｎｓ反应，制得（－）－３－（４－甲氧基苯基）－环氧乙烷－２－羧酸薄荷酯（４）和（－）－３－（４－甲氧基苯基）－环氧乙烷－２－羧酸冰片酯（５），并利用＾１Ｈ－ＮＭＲ谱确定了它们顺反构型，推测了分离得到的ｃｉｓ－４ａ和ｃｉｓ－４ｂ中手性碳（Ｃ２，Ｃ３）的绝对构型。

关键词： 不对称性   手性   对映体   旋光性   化合物  

摘要： 不对称性(asymmetry)是自然界中广泛存在的一种现象。在宏观上,如果一个物体不存在任何对称因素,那么该物体就具有不对称性。其重要特征是该物体与它的镜象不能互相重叠。不对称物体的这种不可重叠性正如人的左右手关系一样,故又常称为手性(chirality)。自然界的这种不对称现象在化学和生命科学中有着广泛的应用。

关键词： 光催化   缬氨酸   复合物   半导体  

摘要： 本文研究了在甲醇和氨水的水溶液里，手性的（＋）－ｄｉｏｐ－Ｒｈ（Ⅰ）复合物（ｄｉｏｐ：２，３－邻－异亚丙基－２，３－二羟基－１，４－双（二苯膦基）丁烷）作为不对称催化剂，粉末半导体ＣｄＳ、ＴｉＯ＿２、Ｐｔ／ＣｄＳ和Ｐｔ／ＴｉＯ＿２为光催化剂，用５００ＷＸｅ灯光照１０ｈ，３－甲基－２－氧代丁酸光催化不对称合成Ｌ－α缬氨酸已经实现，光学纯度最高达６４％ｅ．ｅ．。

关键词： 手性配体   不对称合成   催化反应   对称轴   综述  

摘要： 按配位原子的数目进行分类，综述了近年来研究较多的具有Ｃ_２对称轴的手性配体及其相关的不对称催化反应，并对该类手性配体的设计做了分析和总结。参考文献７９篇。

关键词： 电化学   不对称合成   诱导作用   光学活性  

摘要： 综述了电化学不对称合成的研究概况，按照诱导手性方式的不同分六类加以介绍。参考文献５８篇。

摘要： Amidocuprate(I) reagents {Li[Cu(NR(2))(2)]} and higher order cyanocuprates(I) {Li-2[Cu(CN)(NR(2))(2)]} have been developed as a new class of nitrogen nucleophiles. These reagents underwent regioselective 1,4-additions to alpha,beta:gamma,delta-dienoates, whereas NHR(2) gave a 1,6-addition product and the lithium reagent LiNR(2) afforded a mixture of 1,4- and 1,2-addition products. The amidocuprates(I) were added to chiral alpha,beta:gamma,delta-dienones having a 8-phenyl-p-menth-3-yl or a 10,2-bornanesultam chiral auxiliary in order to produce 1,4-adducts in good to high diastereoselectivity. The addition of Li[Cu{N(Bn)(TMS)}2] and Li-2[Cu(CN){N(Bn)(TMS)}(2)] to 8-phenyl-p-menth-3-yl 5-phenyl-2,4-pentadienoate or N-(5-phenyl-2,4-pentadienoyl)-10,2-bornanesultam produced an (R)-chirality at the beta-position. The 1,4-addition of Li-2[Cu(CN)(N(Bn)(TMS))(2)] to the bornanesultam, followed by trapping with acetaldehyde, gave the alpha-(1-hydroxyethyl)-beta amino derivative as a single isomer in good yield. This three-component coupling was used in an asymmetric synthesis of a beta-lactam.

关键词： .enantioselective synthesis   shown in Fig  

摘要： Homochiral diene diols of type 1, derived biocatalytically by microbial dioxygenation of halogenated aromatic compounds, have served as precursors to a number of oxygenated natural products. Specifically, D-chiro-inositol (9), D-erythuronolactone (10), (+)-lycoricidine (14), (+)-kifunensine (19), and L-threosphingosine (25) have all been synthesized from 1.

关键词： .DIBAL   synthesis of natural   chiral sulfoxides   nonactic  

摘要： The macrolide cladospolide A and of (+) (2S, 3S, 6R, 8R) - nonactic and (-) (2R, 3R, 6S, 8R)-epi-nonactic acids were, enantioselectively prepared. The formation of the chiral centers was controlled by a chiral sulfoxide group.

关键词： .cholestane   pentols  

摘要： 5beta-cholest-24-ene-3alpha,7alpha,12alpha-triol was efficiently converted to the corresponding (24R and 24S) isomers of 5beta-cholestane-3alpha,7alpha,12alpha,24,25-pentols with the Os-catalyzed Sharpless asymmetric dihydroxylation process. Utilizing a new phthalazine class of cinchona alkaloid based ligands, namely (DHQD)2PHAL and (DHQ)2PHAL and the use of methylsulfonamide for the acceleration of the reaction rate, the enantiomeric excess achieved ranged from 95-98%. The absolute configurations and enantiomeric excess of the (24R,24S)-5beta-cholestane-3alpha,7alpha,12alpha,24,25-pentols achieved were confirmed by the lanthanide-induced CD Cotton effect Measurements.