《化学通报》网络版(Chemistry Online)2005年第7期论文摘要

[w074]环氧化合物的不对称开环反应AsymmetricRingOpeningofEpoxides王朝阳(西南交通大学药学院四川峨眉614202)介绍了在不同手性配体和路易斯酸的催化下内消旋环氧化合物的不对称开环反应与外消旋末端环氧化合物的水解动力学拆分与开环反应;并指出了环氧化合物的这两种反应在不对称合成与手性药物领域的应用价值以及在工业上广阔的应用前景。Progressesinasymmetricringopening(ARO)ofmesoepoxideswithdifferentchiralligand,andthehydrolytickinetic resolution(HKR)ofracemicterminalepoxidescatalyzedbychiralSalenmetalcomplexwer…     

S-烷基异硫脲盐作为硫醇替代物经环氧开环反应合成β-羟基硫化物

S-烷基异硫脲盐作为一种无毒、无味、易于制备的硫醇替代物，在碱性水介质中、室温下与多种环氧化合物发生环氧开环反应，区域选择性、高收率地合成了一系列β-羟基硫化物。     

1,1,3,3-四(全氟己基乙基)二锡氧烷二聚体在环氧化合物开环反应中的催化作用

采用氟碳-有机溶剂两相催化体系,考察了1,1,3,3-四(全氟己基乙基)二锡氧烷二聚体(1)在环氧化合物开环反应中的催化作用.结果表明,催化剂(1)在氟碳-有机溶剂两相体系中使环氧苯乙烯和甲醇的开环反应产率高达95%,¹³CNMR谱表明,开环反应的区域选择性为100%.在氟碳-有机溶剂两相催化体系中以一锅法制备了3-苯基丙酸2-甲氧基-2-苯乙醇酯,收率高,方法简便,催化剂几乎可以定量回收循环使用.     

光学活性Zoapatanol类似物的合成研究 - 关键中间体的合成

手性合成原2经格氏反应、甲基烯丙醇双阴离子环氧化合物开环等七步反应,合成了光学活性Zoapatanol类似物1b的关键中间体8. 化合物5a～8的新手性中心经证明为S构型。     

氯化锌催化硒酚对环氧化合物开环反应合成β-羟基硒醚

 研究了在室温下ZnCl2催化硒酚对环氧化合物开环反应合成β-羟基硒醚. 通过这一简单、有效和原子经济性的反应,高收率和高选择性地合成了几种β-羟基硒醚. 从环氧化合物3-邻甲苯氧基-1,2-环氧丙烷出发,经一锅三步反应,合成了相应的1,3-恶唑-2-酮.     

锆氢化反应研究 VI:环氧化合物的选择还原

环氧化合物还原成醇,是较为常见的反应。其区域选择性取决于所使用的还原剂。一般规律是:LiAlH_4类型的亲核性复合金属氢化物从空间障碍较小的部位接近氧,从而获得取代基较多的醇;而硼烷(尤其在BF_3存在之下)或铝烷类型的亲电性金属氢化物则使环氧化合物从相反方向开环并主要获得取代基较小的醇。锆氢试剂(Cp_2ZrHCl)对羰基化合物的还原已经详细研究,本文将研究环氧化合物的还原及其区域选择性,并进一步认识锆氢试剂在反应中的作用及其本质。     

五元氮杂环的开环反应研究进展

综述了近年来各种五元氮杂环的开环反应及其在有机合成中的应用。杂环化合物在有机合成中的作用越来越重要,五元氮杂环是其中最重要的一部分,其开环反应可以用来合成某些用其它方法难以合成的多官能团化合物,或通过开环和修饰合成其它环状化合物,还可以作为保护基以及研究仿生合成领域中各类复杂的生化反应等。     

右旋肌醇甲醚腺嘌呤核苷类似物的合成

以右旋肌醇甲醚为原料,经保护的甲烷磺酸酯与腺嘌呤缩合,合成了腺嘌呤核苷类似物5.此外,化合物3经酸水解,再经环氧化高产率地合成了重要的中间体7,腺嘌呤在强有机碱存在下,对环氧化合物7进行区域性的开环反应,合成了另外两种腺嘌呤核苷类似物8和9.     

环氧化天然橡胶二次改性的研究进展

环氧化天然橡胶(ENR)分子链中存在易开环的反应性环氧基团,环氧基团的开环反应为ENR进行进一步的改性提供了极大的方便。ENR选择性氢化双键可以提高其抗热氧稳定性;ENR与胺类化合物和含磷化合物的反应,可以将防老剂和阻燃剂负载到ENR分子链上,从而达到在分子尺寸的分散;可以利用环氧基团的选择性氧化裂解制备NR基嵌段共聚物的前驱体遥爪型NR;通过环氧基团可以进行接枝改性其它聚合物;此外,分子链中的环氧基团使ENR与无机填料和其它极性聚合物共混相容性提高。     

胍催化邻苯二甲酰亚胺对环氧化合物的开环反应

作为有机强碱,胍类化合物可用于催化多种反应[1 5],并且反应可以在均相、无水条件下进行,不需要相转移催化剂。本文探讨用胍催化邻苯二甲酰亚胺对环氧化合物进行开环。用三光气将二乙胺转变为四乙基脲1,后者用五氯化磷和叔丁胺处理得到1,1,3,3 四乙基 2 叔丁基胍2。用2催化邻苯二甲酰亚胺与末端环氧化合物的反应,实现了环氧化合物的区域选择性开环。合成路线如下:1　实验部分1 1仪器与试剂WC 1型显微熔点仪(四川大学科仪厂),温度计未校正;Carlo ErbaModel1110自动元素分析仪,Varian400MHz核磁共振仪。溶剂和试剂经干燥、重蒸后使用…     

生物催化烯烃不对称环氧化反应

手性环氧化物在合成上具有重要的应用价值。近年来,制取这些手性合成物的合成方法取得了很大的发展。文章重点讨论了生物催化手性前体烯烃不对称合成光学活性环氧化合物的发展状况。     

Melamine Sulfonic Acid: A Recoverable Catalyst for the Ecofriendly Synthesis of Thiocyanohydrins Under Solvent-Free Conditions

Melamine sulfonic acid as a novel and efficient solid acid catalyst has been synthesized and used in the ring opening of epoxides under solvent-free conditions. This catalyst afforded the corresponding thiocyanohydrins with good regioselectivity and very short reaction times. The catalyst can be easily separated and reused several times without appreciable loss of activity. The availability and recoverability of the catalyst with easy operation and workup make this method attractive for organic synthesis.     

生物催化合成光学活性环氧化物

手性环氧化物及其相应的邻二醇在合成上具有重要应用价值。近年来,制取这些手性合成块的合成方法得到了很的大发展。本文着重讨论当前国际上采用生物催化合成光学活性环氧化物的发展状况。     

Facile Amberlyst A-21 catalyzed access of β-hydroxynitriles via epoxide opening in water

β-Hydroxynitriles are essential intermediates in the synthesis of diverse bioactive compounds and clinical drugs. One of the precursor reactions to these intermediates is the opening of an epoxide ring with a cyanide nucleophile. In the present study, we report a milder and safer route to β-hydroxynitriles employing recyclable, Amberlyst A-21 resin in the ring-opening of epoxides with acetone cyanohydrin in water. A diverse range of substrates (fifteen), including aromatic epoxides, phenoxy epoxides, non-terminal, and terminal aliphatic epoxides, are investigated under the optimized conditions to afford the desired β-hydroxynitriles in good to excellent yield. In addition to this, the recyclability of the Amberlyst A-21 resin is also successfully demonstrated. This relatively safer methodology has the potential to be explored in other organic transformations.     

Halogen-free processes for organic carbonate synthesis from CO2

Recent progress on the synthesis of organic carbonates by halogen-free processes has been reviewed. With CO₂ as a cheap and non-toxic feedstock, alcohols, epoxides and olefins can convert to abundant organic carbonates, e.g. dialkyl carbonates, five- or six-membered cyclic carbonates and polycarbonates. To avoid environmental pollution and equipment corrosion, new synthesis routes which exclude traditional halogen-containing catalysts and solvents have caused much attention. Effective alternatives mainly include the organic/inorganic bases and metal-complexes catalysts. In addition, novel carriers for the catalysts are being applied in these processes to improve the activity and facilitate the recovery.     

Multicomponent linchpin couplings. Reaction of dithiane anions with terminal epoxides, epichlorohydrin, and vinyl epoxides: efficient, rapid, and stereocontrolled assembly of advanced fragments for complex molecule synthesis

The development, application, and advantages of a one-flask multicomponent dithiane linchpin coupling protocol, over the more conventional stepwise addition of dithiane anions to electrophiles leading to the rapid, efficient, and stereocontrolled assembly of highly functionalized intermediates for complex molecule synthesis, are described. Competent electrophiles include terminal epoxides, epichlorohydrin, and vinyl epoxides. High chemoselectivity can be achieved with epichlorohydrin and vinyl epoxides. For vinyl epoxides, the steric nature of the dithiane anion is critical; sterically unencumbered dithiane anions afford S(N)2 adducts, whereas encumbered anions lead primarily to SN2' adducts. Mechanistic studies demonstrate that the SN2' process occurs via syn addition to the vinyl epoxide. Integration of the multicomponent tactic with epichlorohydrin and vinyl epoxides permits the higher-order union of four and five components.     

Hydrotrope promoted in situ azidonation followed by copper catalyzed regioselective synthesis of β-hydroxytriazoles

Research on Chemical Intermediates - The rapid method for the synthesis of organic azides was achieved by employing azide acceptors such as halides, epoxides and pseudohalides like diazonium salts...     

Synthesis of a Pyridine–Zinc‐Based Porous Organic Polymer for the Co‐catalyst‐Free Cycloaddition of Epoxides

The synthesis of solid catalysts for the co‐catalyst‐free cycloaddition of CO₂ has attracted much attention. Herein, we report a hierarchical porous organic polymer, Py‐Zn@MA, that is able to catalyze the cycloaddition reaction of epoxides and CO₂ without using any additives or co‐catalyst to afford turnover frequency (TOF) values as high as 250 and 97 h⁻¹ at 130 °C by using pure and diluted CO₂ (simulating flue gas), respectively. These results are superior to those obtained from previously reported heterogeneous co‐catalyst‐free systems. The high activity of Py‐Zn@MA is mainly attributed to its bifunctional nature with ZnBr₂ and pyridine activating the epoxide in a cooperative way. Notably, Py‐Zn@MA can be easily prepared on a large scale without using any catalyst and the chemicals are cost effective. Moreover, Py‐Zn@MA shows good substrate universality for the cycloaddition reactions of epoxides. Our designed porous organic polymer Py‐Zn@MA material has the potential to serve as an efficient catalyst for the direct conversion of flue gas with epoxides into value‐added cyclic carbonates.     

绿色路易斯酸三卤化铟在有机合成中的应用

三卤化铟作为温和的路易斯酸可在水、醇等绿色溶剂中实现高化学选择性、高 区域选择性和高立体选择性的化学转化。综述了三卤化铟在羟醛反应和类羟醛-曼 尼希反应、Fiedel-Crafts反应、环氧化合物的重排反应、α-氨基膦酸的合成、喹 啉环系的构建、酯交换反应、Diels-Alder反应和杂Diels-Alder反应,手性呋喃二 醇的合成、水相中的叠氮解反应和二硫缩醛的制备中的应用,同时还总结了本课题 组将三卤化铟应用于Biginelli反应和还原脱氧反应的反应结果。三卤化铟在有机 合成中潜在的优势将推动“绿色化学”的发展。     

锌和锡参与下末端环氧化物的选择性烯丙基化反应

烯丙基溴和金属辛或锡成功地将末端环氧化合物1一锅法合成高烯丙基醇2和双高烯丙基醇3. 还研究了环氧化合物取代基的影响, 并提出了此烯丙基化的反应途径 .