共查询到19条相似文献,搜索用时 93 毫秒
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将以烯烃为原料通过Sharpless不对称双羟化等多步反应合成的8种手性β-氨基醇, 作为有机小分子催化剂, 用于催化α,β-不饱和酮的不对称环氧化反应.考察了影响对映选择性的催化剂结构、催化剂用量、氧化剂种类、溶剂、反应温度等因素.结果表明, 当催化剂用量为30 mol%、氧化剂为TBHP(叔丁基过氧化氢)、正己烷溶剂、在室温下、以(1S,2R)-(+)-1,2-二苯基-2-甲氨基乙醇(3)作催化剂时, 所得环氧化物的对映体过量最高为70% ee, 产率最高为84%. 相似文献
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催化的不对称二羟基化反应 总被引:1,自引:0,他引:1
综述了不对称二羟基化反应的一般原理、反应历程,介绍了常用配体的种类、合成方法、应用范围和反应条件以及不对称二羟基化反应在有机合成中的应用。 相似文献
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手性环氧化合物是有机合成的重要中间体,由于三元杂环的张力使其很容易与各种亲核试剂作用,通过官能团转化反应,可以从环氧化物制备一系列不同结构的手性化合物.烯烃的不对称环氧化反应可以使潜手性的烯烃转化为带有手性碳的环氧化合物,在医药、农药、香料等精细化学品的合成上具有非常重要的意义.非官能化烯烃经手性催化剂诱导的不对称环氧化反应是获得光学纯手性化合物的有效方法.这些手性催化剂包括生物酶、金属卟啉、金属Salen配合物以及有机小分子催化剂.本文综述了这几种催化剂催化的非官能化烯烃不对称催化环氧化反应近几年的研究进展,介绍了催化剂的催化机理,并就其发展趋势提出了构想. 相似文献
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不对称催化环氧化反应 总被引:5,自引:0,他引:5
本文综述了不对称催化环氧化体系的研究进展。重点评述了Sharpless-Kat-suki不对称环氧化反应的特点、机理、新进展与应用,综合分析了由手性(salen)Mn(Ⅲ)催化剂对非功能化烯烃所创建的突出成果与应用前景。 相似文献
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本文介绍了手性铁催化体系在酮及亚胺的不对称还原、烯烃及硫醚的不对称氧化、不对称环加成、不对称环丙烷化以及不对称Friedel-Crafts烷基化等反应中的应用. 相似文献
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On the Mechanism of the Organocatalytic Asymmetric Epoxidation of α,β‐Unsaturated Aldehydes 下载免费PDF全文
Dr. Rebecca L. Davis Dr. Kim L. Jensen Dr. Björn Gschwend Prof. Dr. Karl Anker Jørgensen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(1):64-67
Mechanistic studies on the organocatalytic epoxidation of α,β‐unsaturated aldehydes explore the autoinductive behavior of the reaction and establish that the hydrate/peroxyhydrate of the product is acting as a phase‐transfer catalyst. Based on these studies, an improved methodology that provides high selectivities and decreased catalyst loading, through the addition of chloral hydrate, is developed. 相似文献
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S Koya Y Nishioka H Mizoguchi T Uchida T Katsuki 《Angewandte Chemie (International ed. in English)》2012,51(33):8243-8246
A complex situation: Asymmetric epoxidation of conjugated olefins was achieved at room temperature using ruthenium complex 1 as the catalyst and air as the oxidant to give epoxides in up to 95?%?ee. When the product was acid sensitive, the reaction was carried out at 0?°C under oxygen. 相似文献
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Albert Moyano Prof. Niama El‐Hamdouni Ahmed Atlamsani Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(18):5260-5273
Rearrangement reactions often lead to the regio‐ and stereoselective formation of carbon–carbon or carbon–heteroatom bonds, and allow the construction of otherwise hard‐to‐access molecular frameworks. Research disclosed in the present decade, especially in the last two years, has shown that organocatalytic modes of activation can be successfully applied to a variety of rearrangements. In this Minireview we discuss the advances achieved so far in asymmetric organocatalytic rearrangement reactions. 相似文献
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For the preparation of metal ion-planted MCM-41 we have developed a template ion-exchange method, in which the template ions of as-synthesized MCM-41 are exchanged for the metal ions in aqueous media. The cations of Al, Ti, Cr, Mn, Zn, and Zr could be incorporated with high dispersion, while those of Fe, Co, Ni, Cu, Ga, Pd, and Pt formed small particles on the outside of the MCM-41 particles. Investigation on the time course of the template ion-exchange process suggested that the exchange proceeded first between the template ion and a proton and subsequently between the proton and a metal cation. Among the resulting metal ion-planted MCM-41s, Mn-MCM-41 showed excellent activity for the epoxidation of aromatic olefins. Trans-stilbene oxide was obtained in 93% yield from stilbene in MeCN–DMF solution at 328 K for 96 h. Ti-MCM-41 was the most suitable catalyst for the oxidation of sulfide with H2O2. It should be noted that the oxidation proceeded asymmetrically on Ti-MCM-41 in the presence of optically active tartaric acid in a CH2Cl2 solution. The chemical yield and optical yield of sulfoxide reached 54 and 30% ee, respectively. 相似文献
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重点从立体选择性和催化机理方面,总结了不同的有机小分子催化剂在烯酮的[2+2]和[4+2]不对称环加成反应中的应用. 相似文献