共查询到19条相似文献,搜索用时 62 毫秒
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在许多不对称有机反应中,手性伯胺催化剂已被证实是一种高效的催化剂,被广泛应用于各种Michael加成反应中。Michel加成是有机合成中构建碳一碳键的重要反应之一,本文综述了近年来手性伯胺催化剂在Michael加成反应中的研究新进展。 相似文献
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合成了迄今未有报道的新型有机催化剂,并研究了在该有机催化下水相中不同类型的酮与各种硝基烯烃的反应。研究表明:水相中进行的Michael加成反应在合成的新型有机催化剂的作用下,有较高的产率(最高达93%)和较好的对映选择性,ee值最高达96%。 相似文献
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以β-CF_3-β-(3-吲哚)硝基烯烃衍生物和丙二酸酯为反应起始原料,在碳酸铯碱性条件下,用甲苯作为反应溶剂,于35℃下搅拌反应,实现了β-CF_3-β-(3-吲哚)硝基烯烃衍生物与丙二酸酯的Michael加成反应。通过对碱、反应溶剂、碱的用量、底物浓度和反应温度等因素的考察,确定了反应的最优条件。然后,在最优条件下,实现了不同结构的β-CF_3-β-(3-吲哚)硝基烯烃与丙二酸酯的Michael加成反应,以最高95%的收率获得了既含三氟甲基又含吲哚片段的γ-硝基丁酸酯,其结构均经过~1HNMR、~(13)CNMR、ESI-HRMS和IR确证。 相似文献
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有机小分子催化剂以其相对廉价易得、无金属参与、对环境污染小、催化活性良好的优势,受到许多化学家的关注。在醛、酮与硝基烯类的不对称Michael加成反应中也得到成功的应用。本文综述近几年来,硝基烯类化合物参与的与醛、酮不对称Michael加成反应的各类α,β-不饱和有机底物以及所用到的有机小分子催化剂。总结其优缺点,以期待能够更加广泛的催化剂被研制出来。 相似文献
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Zhigang Yang Jie Liu Xiaohua Liu Zhen Wang Xiaoming Feng Zhishan Su Changwei Hu 《Advanced Synthesis \u0026amp; Catalysis》2008,350(13):2001-2006
A highly diastereoselective and enantioselective Michael addition of cyclohexanone, acetone and other ketones to nitroolefins was developed by the use of an amine organocatalyst based on bispidine. Additionally, a theoretical study of transition structures revealed that this bispidine‐based primary‐secondary amine catalyst could serve through an enamine intermediate and H‐bond interaction, which was important for the reactivity and selectivity of this reaction. 相似文献
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Yan Xiong Yuehong Wen Fei Wang Bo Gao Xiaohua Liu Xiao Huang Xiaoming Feng 《Advanced Synthesis \u0026amp; Catalysis》2007,349(13):2156-2166
The chiral functionalized salt catalysis, which differs from the known enzyme‐ and transition metal‐based methods, has been successfully developed to carry out the Michael addition of ketones to nitroolefins. Chiral anion salt (type I ), chiral cation salt (type II ), or chiral anion‐chiral cation salt (type III ) could be expected to be remarkably effective catalysts and afford the corresponding chemically and optically pure Michael addition adducts. A primary amine group activating the ketone during salt catalysis was their obvious and common property. Based on preliminary experimental investigations and previous reports on primary amine catalysis, a reaction pathway via imine, enamine, iminium ion to imine was proposed. 相似文献
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A polymer‐supported α,α‐diarylprolinol silyl ether displays catalytic activity and enantioselectivity comparable to the best homogeneous catalysts in the Michael addition of aldehydes to nitroolefins. Above all, the combination of polymer backbone, triazole linker, and catalytic unit confers to it an unprecedented substrate selectivity in favor of linear, short‐chain aldehydes. 相似文献
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Rubn Manzano Jos M. Andrs María D. Muruzbal Rafael Pedrosa 《Advanced Synthesis \u0026amp; Catalysis》2010,352(18):3364-3372
A highly diastereo‐ and enantioselective conjugate addition of β‐keto esters to nitroolefins, catalyzed by a chiral thiourea prepared from L ‐valine is described. The formation of two contiguous tertiary and quaternary stereocenters occurs in high yield and excellent diastereo‐ and enantioselection with only 2 mol% of catalyst loading. The reaction is general and different β‐keto esters and aryl‐ and alkylnitroolefins have been tested. The same catalyst has been used to promote the first intramolecular conjugate addition leading to the cyclic adduct in moderate diastereoselectivity and good enantioselectivity. 相似文献
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简介了ⅣB族金属-钛、锆和铪取代的膦叶立德的各种合成方法及它们与酮、醇和一氧化碳的反应。 相似文献
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Michail Tsakos Christoforos G. Kokotos George Kokotos 《Advanced Synthesis \u0026amp; Catalysis》2012,354(4):740-746
Among the class of primary amine‐thioureas based on tert‐butyl esters of α‐amino acids, the most efficient organocatalyst for “difficult” Michael reactions was identified. The derivative based on (S)‐di‐tert‐butyl aspartate and (1R,2R)‐diphenylethylenediamine provided the products of the reaction between aryl methyl ketones and nitroolefins in excellent yields and enantioselectivities. In addition, this new catalyst can be used at low catalyst loading (5 mol%). The utility of this methodology was highlighted by the efficient synthesis of (S)‐baclofen, (R)‐baclofen and (S)‐phenibut. 相似文献
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