共查询到18条相似文献,搜索用时 125 毫秒
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手性季铵盐作为相转移催化剂(Phase-transfer catalysts ,PTC) 能使非均相反应在温和条件下进行,操作简单,反应速率加快,产率明显提高,因此这一技术在有机合成中具有广泛的应用.这些季铵盐主要是以金鸡钠生物碱衍生的[1,2],近年来出现了一些其它类型的季铵盐[3],但是它们的制备一般比较困难,大多数催化效果不是很理想;并且这些季铵盐的结构有一定局限,改造比较困难.同时这些季铵盐大都是 C-手性的,很少有N-手性的[4,5];在以前的不对称反应中,有意识地构建N-手性季铵盐及N-手性在不对称反应中的作用鲜有报道[6]. 相似文献
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手性相转移催化剂及其在不对称催化反应中的应用 总被引:1,自引:0,他引:1
综述了手性季铵盐、手性冠醚以及其它新型手性相转移催化剂的制备及其在各种不对称相转移催化反应如烷基化反应、Michael加成反应、Aldol反应、Mannich反应、氧化反应及还原反应中应用的最新进展. 相似文献
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制备了多壁碳纳米管(MWCNTs)固载的金鸡纳生物碱季铵盐类手性相转移催化剂PTC-1/MWCNTs,并用于催化N-二苯亚甲基-甘氨酸叔丁酯的不对称烷基化反应中.采用紫外-可见光谱系统研究了五种有机溶剂对PTC-1在MWCNTs上吸附和脱附的影响.结果表明,在甲苯中,MWCNTs对PTC-1的吸附率最高(53%),而在三氯甲烷中PTC-1的脱附率最低(仅为0.75%).PTC-1/MWCNTs催化剂在催化N-二苯亚甲基-甘氨酸叔丁酯和不同卤代烃的不对称烷基化反应中,所得产物的收率和对映体选择性都较高,而且该催化剂可回收循环使用,说明PTC-1经MWCNTs固载后,仍能够有效地催化多种卤代烃的不对称烷基化反应. 相似文献
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以交联聚苯乙烯(CPS)微球为载体,通过高分子反应和配位反应,简捷高效地制得一种新型的聚合物固载的手性Salen金属配合物催化剂Mn(Ⅲ)Salen-CPS.以间氯过氧苯甲酸(m-CPBA)为氧化剂、以N-甲基吗啉-N-氧化物(NMO)为轴向配体,将该非均相手性Salen Mn(Ⅲ)催化剂用于苯乙烯的不对称环氧化反应,深入系统地研究了催化剂结构与反应条件对苯乙烯的不对称环氧化反应的影响.实验结果表明,在苯乙烯的不对称环氧化反应中,微球Mn(Ⅲ)Salen-CPS具有高的催化活性与良好的的对映体选择性,20℃下反应8 h,苯乙烯的转化率可达85%;0℃下反应2 h,产物的ee值可达58%.Salen配基中手性二胺的不对称环境与轴向配体NMO的加入均可明显地提高产物的对映体选择性;而反应温度、时间、溶剂的极性及催化剂用量等反应条件对苯乙烯的不对称环氧化反应也都有很大的影响.低温有利于产物的ee值的提高,苯乙烯的不对称环氧化反应适宜的反应温度为0℃;使用极性弱的溶剂,有利于催化剂的对映体选择性;当反应进行到一定程度,产物的ee值会出现最高值,其后ee值会随时间延长呈现下降趋势,在不同的反应条件下,ee值出现最大值的时间不同. 相似文献
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以交联聚苯乙烯(CPS)微球为载体,通过高分子反应和配位反应,简捷高效地制得一种新型的聚合物固载的手性Salen金属配合物催化剂Mn(Ⅲ)Salen-CPS.以间氯过氧苯甲酸(m-CPBA)为氧化剂、以N-甲基吗啉-N-氧化物(NMO)为轴向配体,将该非均相手性Salen Mn(Ⅲ)催化剂用于苯乙烯的不对称环氧化反应,深入系统地研究了催化剂结构与反应条件对苯乙烯的不对称环氧化反应的影响.实验结果表明,在苯乙烯的不对称环氧化反应中,微球Mn(Ⅲ)Salen-CPS具有高的催化活性与良好的的对映体选择性,20℃下反应8h,苯乙烯的转化率可达85%;0℃下反应2h,产物的ee值可达58%.Salen配基中手性二胺的不对称环境与轴向配体NMO的加入均可明显地提高产物的对映体选择性;而反应温度、时间、溶剂的极性及催化剂用量等反应条件对苯乙烯的不对称环氧化反应也都有很大的影响.低温有利于产物的ee值的提高,苯乙烯的不对称环氧化反应适宜的反应温度为0℃;使用极性弱的溶剂,有利于催化剂的对映体选择性;当反应进行到一定程度,产物的ee值会出现最高值,其后ee值会随时间延长呈现下降趋势,在不同的反应条件下,ee值出现最大值的时间不同. 相似文献
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G. P. Shkil' L. V. Berdovich V. Lusis D. Mutsenietse R. S. Sagitullin 《Chemistry of Heterocyclic Compounds》1995,31(1):76-79
Some quaternary salts of asymmetric substituted pyridines with functional group at the 3- and 5-positions have been synthesized. It has been established that when there is an ester group present, the latter participates in the recyclization of the salts on treatment with alkali, resulting in the formation of pyridine-2-ones. 相似文献
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Highly active polymeric organocatalyst: Chiral ionic polymers prepared from 10,11‐didehydrogenated cinchonidinium salt 下载免费PDF全文
Md. Mehadi Hassan Naoki Haraguchi Shinichi Itsuno 《Journal of polymer science. Part A, Polymer chemistry》2016,54(5):621-627
Since few examples of 10,11‐didehydrogenated (3‐ethynyl) cinchona alkaloids have been utilized as organocatalysts in asymmetric reaction, we synthesized 10,11‐didehydrogenated cinchonidine. The 3‐vinyl group of cinchonidine was transformed into a 3‐ethynyl functionality. Based on the resulting 10,11‐didehydrogenated cinchonidine, the corresponding quaternary ammonium salt and its dimers were prepared. The ion‐exchange reaction between the quaternary ammonium salt and sodium sulfonate produced the quaternary ammonium sulfonate as a stable ionic compound. Chiral ionic polymers were then synthesized by the ion‐exchange polymerization of the 10,11‐didehydrogenated cinchonidinium salt dimer and a disulfonate. The chiral ionic polymers were found to be capable of efficiently catalyzing the asymmetric alkylation of N‐(diphenylmethylene)glycine tert‐butyl ester. The enantioselectivities obtained with the polymeric catalysts were higher than those obtained with the corresponding monomeric catalyst. Dimers of 10,11‐didehydrogenated cinchonidinium salts were prepared. Treatment of the dimer with disodium disulfonate gave the chiral ionic polymers, which showed high catalytic activity in asymmetric benzylation of N‐(diphenylmethylen)glycine tert‐butyl ester. The polymeric catalysts were reused several times without the loss of catalytic activity. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 621–627 相似文献
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Jian Bin LUO Qiang WANG Hong TAN Jie Hua LI Yin Ping ZHONG College of Polymer Science Engineering Sichuan University Chengdu College of Chemistry & Environment Protection Engineering Southwest University for Nationalities Chengdu Key Laboratory of Bio-resources Eco-environment 《中国化学快报》2006,(11)
In order to resolve the increasing resistance phenomena of the Gram-negative bacteria against single chain quaternary ammonium salts (QAS), lysine with a pedant fluorinated bis-ammonium salts was synthesized and its antimicrobial properties were evaluated in this work. The novel fluorinated bis-ammonium salts shows similar activity with conventional single chain quaternary ammonium salts against Gram-positive bacteria but stronger activity against Gram-negative bacteria and yeast compared with the single chained counterpart. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(17):4897-4901
Although chiral quaternary ammonium and phosphonium salts are commonly used for asymmetric organocatalysis, the catalytic ability of chiral tertiary sulfonium salts has yet to be demonstrated in asymmetric synthesis. Herein, we show that chiral bifunctional trialkylsulfonium salts catalyze highly enantioselective conjugate additions of 3‐substituted oxindoles to maleimides under base‐free neutral phase‐transfer conditions. 相似文献
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手性相转移催化剂及其不对称催化反应 总被引:10,自引:1,他引:10
综述了手性季铵盐和手性冠醚两类手性相转移催化剂及其在不对称催化反应(包括加成,取代,氧化及还原等反应)中的应用,参考文献97篇。 相似文献
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Resin-OsO4-金鸡纳生物碱:一种在(E)-二苯乙烯不对称双羟化反应中可循环使用的高效催化剂 总被引:1,自引:0,他引:1
用改进的方法把季铵盐共价结合在Merrifield树脂上作为离子交换剂与K2O5O4作用制成Resin—OsO4催化剂,在NaH存在下,以DMF作溶剂,在70℃下奎宁或奎尼丁与1,4-二氯二氮杂萘反应高产率地生成(QN)2PHAL或(QD)2PHAL,Resin—OsO4通过简单过滤可定量回收,回收的催化剂重复使用五次,其活性不变,Resin—OsO4-(QN)2PHAL或(QD)2PHAL催化体系在(E)-二苯乙烯的不对称双羟化反应中的化学产率为84~91%,立体选择性为96-99%ee。 相似文献