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在过渡金属催化下,苯基重氮乙酸甲酯分解产生的卡宾与苄醇生成羟基叶立德,与N-甲基靛红发生类似于羟醛缩合的反应.铜催化剂和其他路易斯酸用于催化这类三组分反应中,获得了与二价铑不同的化学和立体选择性.手性铜催化剂初步实现了不对称催化,获得了中等程度的对映选择性. 相似文献
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研究了醋酸铑[Rh2(OAc)4]、手性亚磺酰胺基脲和非手性磺酸共催化的α-重氮酯与酰胺化合物的不对称N—H插入反应.研究发现α-重氮酯在醋酸铑催化下形成金属卡宾,该金属卡宾与酰胺反应生成潜手性活泼叶立德中间体.在催化剂量的手性亚磺酰胺基脲和非手性磺酸存在下,潜手性叶立德中间体发生不对称质子化,合成了手性α-氨基酸衍生物.反应过程中,手性亚磺酰胺基脲和非手性磺酸作为"手性质子梭"催化不对称质子迁移从而实现了反应的对映选择性控制.该方法发展了非手性铑、手性亚磺酰胺基脲和非手性磺酸不对称共催化体系,为合成α-氨基酸衍生物提供了一种新途径,反应收率最高可达84%,对映选择性最高可达77%. 相似文献
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氯溴卡宾与系列取代苯甲醛作用均产生CO(即羰基脱氧产物),取代基的电子效应直接影响CO的产率.捕获反应证实,该反应经历0°,0°型羰基叶立德中间体阶段.氟氯(溴)卡宾与四苯基环戊二烯酮(TPCP)反应除得到高产率的CO外,还生成偕氟卤环戊二烯(8)、双键加成物(9)及其重排产物(10).该类反应以脱CO途径为主,这可能是由于中间体羰基叶立德内部存在着"推-拉"稳定效应和不利于分子内电环化和分子间1,3-偶极加成的0°,90°型构象.本文讨论了这两类反应的微观作用机制. 相似文献
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为了合成咪唑[1,2-a]并吡啶-肼类衍生物,发展了一种以简单易得的甲酰甲基溴化物、2-氨基吡啶衍生物和偶氮二甲酸酯为原料的三分子串联反应的方法.该串联反应先生成咪唑[1,2-a]并吡啶,然后紧接着连续发生C(3)—H键肼基化反应,而不像传统的一步接一步反应的方法.该方法具有操作简单、反应条件温和(无需过渡金属且反应温度低等)以及底物适用性广的特点.实验结果表明,带有给电子取代基的甲酰甲基溴化物和2-氨基吡啶衍生物有利于反应的进行,并以优秀的产率获得目标产物. 相似文献
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手性磺酰胺类化合物在新型药物方面研究中占据越来越重要的地位.我们成功地实现了磺酰胺、芳基重氮乙酸酯以及亚胺的不对称三组分反应.此反应给出了高达85%产率,以及优异的非对映选择性(d.r.>20:1)和对映选择性(最高可达99%ee),为高效构建具有两个手性碳的光学纯磺酰胺类化合物提供了一种快速合成方法.我们将反应放大到了克级规模,并对三组分产物进一步衍生得到一种具有三个手性中心的光学纯含亚砜亚胺骨架的五元环化合物.反应的选择性通过过渡金属与手性磷酸协同催化控制. 相似文献
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Chengjin Wang Shunying Liu Dong Xing Xin Wang Xiang Wu Wenhao Hu 《Tetrahedron》2013,69(52):11203-11208
A three-component reaction based on trapping of ammonium ylides with formaldehyde was first reported. This reaction offers a new strategy for the synthesis of α-aryl serine derivatives and can be extended to the preparation of α-aryl threonine derivatives. Synthetic application of the three component reaction for the preparation of hydroquinoxaline derivative was also demonstrated. 相似文献
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Li Yufeng Shi JieWu Zhengguang Wang XinglongWu Xiaowei Gu JiachaoBu Hongzhong Ma Hongfei 《Tetrahedron》2014
A three-component reaction of one molecule of imine and two molecules of alkynoates is realized with the catalysis of Cu(I)–Fe(III) in a sequential manner to allow the direct synthesis of functionalized pyrroles, during which, one C–N bond and two C–C bonds are formed with high atom economy. This method benefits from easily available starting materials, low-cost catalysts, and convenient operations. 相似文献
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The asymmetric domino three-component Knoevanagel-Diels-Alder addition (ATCDA) reaction, as an important methodology, has been utilized to construct complex product from ordinary starting materials. In this report, many typical organoamine catalysts were investigated to achieve highly efficient asymmetric three-component reaction of enones 2, aldehydes 3 and Meldrum’s acid 4. Various pharmacological multi-substituted spiro[5,5]undecane-1,5,9-triones promoted by 9-amino-9-deoxy-epi-quinine 1 g in one-pot, were obtained in moderate to good yields (up to 81%) with excellent diastereo-(>99:1 dr) and enantioselectivities (up to 97% ee). Meanwhile, based on the controlled experiments and analytical data, a reasonable mechanism of dual-activity for this reaction has been proposed. 相似文献
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[reaction: see text] A practical highly diastereoselective synthesis of 1,2-diamines through carbon-carbon bond formation involving an ammonium ylide intermediate is reported for the first time. By treating methyl phenyldiazoacetate with arylamine and imine in the presence of dirhodium acetate, the erythro diastereomer of methyl 1,2-diaryl-1,2-diaminopropanoate is formed with stereochemical preferences greater than 10:1. 相似文献
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Mohammad Javad Taghizadeh Hamid ArvinnezhadSaadi Samadi Khosrow Jadidi Abdollah JavidanBehrouz Notash 《Tetrahedron letters》2012,53(38):5148-5150
An efficient, one-pot, three-component procedure for the synthesis of a small library of new chiral spirooxindolopyrrolizidines with high regio-, diastereo-, and enantioselectivity, from the 1,3-dipolar cycloaddition of azomethine ylides and optically active cinnamoyl oxazolidinone is described. The process occurs at room temperature in aqueous ethanol as a green solvent and in the absence of any Lewis acids. The oxazolidinone chiral auxiliary is removed in a non-destructive manner. The reaction mechanism is discussed on the basis of the assignment of the absolute configuration of the cycloadducts, and on theoretical calculations. 相似文献
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Three-component reactions of aryl diazoacetates, arylamines and N-sulfonyl aldimines cooperatively catalyzed by squaramides and dirhodium acetate are reported to afford N-sulfonyl α,β-diamino acid derivatives in moderate to good yields and diastereoselectivity. 相似文献
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A Cu-catalyzed three-component reaction of aromatic terminal alkynes with aryl sulfonyl azides and primary fluoroalkyl alcohols for the synthesis of fluoroalkoxyl imidates was developed. This simple method enabled the efficient synthesis of trifluoroethoxyl, pentafluoropropoxyl, and heptafluorobutoxyl imidates in good to excellent yields under mild reaction conditions with excellent functional group tolerance. 相似文献
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An efficient silver-catalyzed, aniline mediated cascade hydroamination/cycloaddition of o-aminoaryl compounds including o-aminoaryl aldehydes, o-aminoaryl ketones with alkynes for the synthesis of 2- or 2,4-substituted quinolines is reported. The reactions proceed with high regioselectivity to afford mono- or disubstituted quinoline derivatives in good to high yields using AgOTf as the catalyst in the air. 相似文献
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J.S. Yadav B.V. Subba Reddy Tapas Maity G.G.K.S. Narayana Kumar 《Tetrahedron letters》2007,48(50):8874-8877
A three-component coupling of aldehydes, homoallylic alcohols and ammonium thiocyanate is achieved in the presence of 10 mol % of In(OTf)3 in refluxing dichloromethane to produce 4-thiocyanotetrahydropyrans in excellent yields with all cis-selectivity. This method is simple, selective and convenient for introducing an SCN group onto a tetrahydropyran ring. 相似文献
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C.V. Asokan Ajith Dain Thomas Ann Maria Jose K.C. Lethesh M. Prasanth K.U. Krishanraj 《Tetrahedron letters》2007,48(32):5641-5643
Simple enolizable ketones such as acetophenones and benzalacetones were treated with malononitrile under Vilsmeier-Haack reaction conditions to afford 2-chloronicotinonitriles. The reaction proceeds via a one-pot chloromethyleneiminium salt mediated three-component reaction followed by sequential cyclization and aromatization under Vilsmeier-Haack reaction conditions. 相似文献