关键词： 不对称合成   聚合物支载   有机合成  

摘要： 聚合物支载的不对称有机合成比相应的小分子合成体系有独特的优越性。本文综述了近10年来取得了较大进展的聚合物支载的不对称有机合成体系。

关键词： 不对称合成   萘普生  

摘要： 按分子内的不对称诱导和不对称催化两种类型介绍了萘普生的不对称合成。

关键词： 取代双环辛酮   不对称合成  

摘要： 在复杂天然产物的手性合成中,对映选择构筑不对称季碳是有机合成工作者面临的挑战之一。海洋天然产物(一)-△^(9(12))-Capnellene是一族具有非线性三环结构的倍半萜类化合物。自70年代中期从软珊瑚中分离鉴定出这类化合物后,开始的合成研究足以表明有机合成家们对此类化合物的兴趣。就我们所知。

关键词： 不对称合成   手性高分子   试剂  

摘要： 不对称有机合成是有机化学的前沿课题之一.本文综述了应用手性高分子试剂和催化剂对潜手性化合物通过不对称氧化、还原、烷基化、加成反应进行不对称合成的进展情况.

关键词： 不饱和醛   立体选择性   不对称诱导   手性中心   二烷基   甲基硅烷   亲核试剂   不对称合成   立体效应   有机金属  

摘要： 本文研究了在γ-手性-α,β-不饱和醛④的一些亲核加成反应中的1,4-不对称诱导效应。研究结果表明:共轭烯醛④与格氏类试剂(RM)的1,2-亲核加成反应,未表现出有意义的非对映立体选择性,这意味着在这类反应中可能存在的电子和立体效应无法通过传递双键系统传递;而在助剂(氯化三甲基硅烷、六甲基磷酸三酰胺和三乙胺)存在下,化合物④和二烷基铜锂的反应,导致了大于98％的1,2-加成选择性和优良的非对映立体选择性(82～95％)。这说明在后者反应中,γ-位的不对称信息已成功地通过π-电子系统进行了传递,从而产生了一个远距离的1,4-不对称诱导效应。通过对反应中立体因素的考察,证实共轭烯醛④中β-位立体阻碍是产生高度的1,2-加成选择性的原因;而饱和醛和共轭烯醛竞争反应的实验结果显示:在与二烷基铜锂的加成反应中,共轭烯醛具有较高的反应活性。因而,作者提议反应的第一步是选择性形成d,π-化合物,然后发生立体选择性的1,2-加成反应。

摘要： Using chiral alcohol precursors, a number of chiral vinyl ethers were prepared by mercuric acetate-catalysed transetherification with butyl vinyl ether. a-Lithiation of (1R)-menthyl vinyl ether was unsuccessful under a variety of conditions. (1S)-(Menthylthio)ethene was prepared from (1S)-menthanethiol but deprotonation was not possible as the thioether was found to decompose rapidly at room temperature. The deprotonation of (R)-phenethyl vinyl ether, (S)-l-(2-naphthyl)-l-ethyl vinyl ether and (S)-l-phenyl-1-butyl vinyl ether and attempted reaction with benzaldehyde yielded none of the a-alkylated adduct but a Wittig rearrangement reaction was seen. The cycloaddition reaction of benzonitrile oxide with a range of chiral vinyl ethers was investigated. The isoxazoline product was isolated as a mixture of two diastereoisomers after flash column chromatography. In most cases the diastereoisomer ratio neared 1:1, but (S)-l-(2-naphthyl)-l-ethyl vinyl ether and 1-phenyl-1-butyl vinyl ether gave a single diastereoisomer of the isoxazoline product, after chromatography, with a variety of nitrile oxides. Conditions have been developed for the removal of the chiral auxiliary but as yet only achiral isoxazolines have been obtained by this method. Attempts at ring deprotonation/alkylation and also the addition of a nucleophile or radical to the isoxazoline C=N bond were hindered by the instability of the isoxazoline adducts. A chiral vinyl pyrrolidinone was also prepared and found to undergo an asymmetric cycloaddition reaction with benzonitrile oxide to yield a single diastereoisomer of the isoxazoline product. The equivalent acrylamide was synthesised and, although this gave a 1:1 mixture of diastereoisomers with both benzonitrile oxide and 2,2-dimethylpropanenitrile oxide, these diastereoisomers could be separated. Removal of the chiral auxiliary yielded hydroxyisoxazolines with an enantiomeric excess of 90-94%. Attempts to investigate the extent of any asymmetric induction i

关键词： 芳基丙酸   酞亚胺   不对称  

摘要： 2-芳基丙酸是一类非甾体消炎镇痛药物,大多数在其羧基的α位有一手性碳,且其某一对映体较之另一对映体往往具有更高的

关键词： 倍半类化合物   光学活性5-甲基-8-羟基双环[3,3,0]-2-辛酮   不对称合成   不对称季碳  

摘要： 通过手性硝基烯胺（4）与α-甲基-δ-戊内酯烯醇锌盐发生加成消除反应解决了倍半萜Capnellene类合成中构筑不对称季碳这个难题,对映体过量（e. e. ）为94％。由L-脯氨酸经14步实现了（一）-△-Capnellene类的合成中间体——光学活性5-甲基-8-羟基双环[3 3,0]-2-辛酮（13）的对映选择合成。

关键词： 不对称合成   不对称放大   非线性效应   手性起源。  

摘要： 在不对称合成反应中，使用低光学纯度的手性源物质得到高光学纯度的产物的现象，称为不对称放大。本文以日本的小国和野依两教授的奠基性工作为中心，对于不对称放大的发现、特点和机理以及发展前景，作扼要的介绍。

摘要： A unified strategy for the asymmetric synthesis of the quinocarcin and naphthyridinomycin families of DNA reactive alkaloids isolated from Streptomyces culture has been developed. Through this efficient synthetic route, the first asymmetric synthesis of ($-$)-quinocarcin was accomplished and an effective asymmetric approach to the naphthyridinomycin series has been demonstrated. Key steps include an auxiliary-controlled intermolecular 1,3-dipolar cycloaddition reaction (116 $\to$ 117) and a stereospecific intramolecular 1,3-dipolar cycloaddition reaction (142 $\to$ 143) to construct the 3,8-diazabicyclo(3.2.1) octane cores (CD ring) of quinocarcin and naphthyridinomycin, respectively. Also, an unprecedented intramolecular imide olefination has been successfully achieved to build up the isoquinoline (B ring) subunit regioselectively. The asymmetric synthesis of ($-$)-quinocarcin allowed unambiguous confirmation of the 11bR absolute configuration by comparison of the optical rotations of the synthetic and natural products. Further NOE and NMR experiments on the synthetic ($-$)-quinocarcin has provided evidence for the controversial cis-fused oxazolidine ring stereochemistry as well as the chair conformation of piperidine ring (C-ring).