共查询到19条相似文献,搜索用时 109 毫秒
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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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α-羰基重氮化合物的卡宾聚合反应(C1聚合反应)是近年发展起来的一类合成碳链聚合物的新反应类型,为合成碳链上每一个碳原子都连接有极性取代基的高度功能化聚烯烃类似物提供了烯烃聚合(C2聚合)无法替代且更为便捷有效的新途径,在功能高分子领域有广阔应用前景。本文详细描述了重氮乙酸酯、重氮乙酰胺和α-重氮酮等化合物在铜、钯、铑等过渡金属催化下的卡宾聚合反应及其反应机理,论述了α-重氮化合物参与的共聚合反应以及双-α-羰基重氮化合物的卡宾聚合反应和共聚合反应。最后,展望了卡宾聚合反应的发展趋势。 相似文献
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本工作利用可见光催化剂和Lewis酸双催化体系,在可见光条件下实现了重氮乙酸乙酯与苯胺衍生物或氮杂芳烃的N-烷基化反应,合成了一系列α-氨基酸类化合物.该反应条件温和,有良好的官能团兼容性和底物普适性.机理验证实验证明该反应涉及了自由基机理,由重氮烷在光催化剂作用下通过proton-coupledelectrontransfer(PCET)过程形成了烷基自由基,并在Lewis酸催化作用下与胺发生自由基偶联反应形成N-烷基化产物.这种新的催化机制进一步丰富了重氮化合物在可见光化学反应中的应用类型与范围. 相似文献
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金属铑盐催化下α重氮环二酮与π键的[3+2]环加成反应是合成复杂的稠杂环化合物的一种简捷有效的新方法,本文重点介绍了α重氮13环己二酮通过这类反应合成呋喃环结构化合物的最新研究成果。 相似文献
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螺吡咯啉吲哚酮化合物含有两种重要氮杂环,由于其独特的结构骨架和存在于天然产物而被广泛关注.吲哚酮的3位与其它环状化合物以螺环形式结合的结构特点是该结构具有潜在药物活性和合成价值的基础,例如抗癌和抗菌活性,以及在合成新配体和有机催化剂上的应用.目前,尽管合成螺吲哚酮的策略已有1,3-偶极环加成、亲核加成及还原环化等,但是发展简单高效的构建螺吲哚酮化合物的方法仍具有很大的吸引力.烯基叠氮同时含有叠氮和烯基两个单元,被广泛应用于构建氮杂环.另一方面,重氮化合物被广泛用作偶联环化合成的底物.基于在叠氮化学和杂环合成方面的工作,我们设想利用3-重氮吲哚-2-酮和烯基氮的环化反应构建螺吲哚酮化合物.文献中有关烯基叠氮和重氮化合物反应的报道较少,主要涉及铑催化的环丙烷化和铜催化的环戊烯合成,在这些反应中烯基叠氮作为二元合成子参与反应,而其它类型的反应鲜有报道,因此我们设想利用烯基叠氮作为三元合成子来参与反应成环.在我们开展工作的同时, Katukojvala小组率先发表了铑催化的重氮烯和烯基叠氮的环化反应构建1-吡咯啉.本文报道了3-重氮吲哚酮和烯基叠氮在铑催化下发生[1+1+3]环化,构建一系列螺吡咯啉吲哚酮化合物.研究从反应条件优化开始,通过对催化剂、原料比、溶剂和温度等参数的筛选,确定了最佳反应条件为1a/2a(1/7), Rh_2(TFA)_4(2.5mol%), 1,2-二氯乙烷(0.1mol/L), 60°C.在标准条件下完成了21个不同基团取代的螺吡咯啉吲哚酮化合物的合成,最高收率可达91%,证实了该反应的普适性.当重氮底物的N原子上不含取代基或取代基为甲基、苄基、苯基、苯甲酰基和磺酰基时,反应均可以顺利发生,其中苯甲酰基和对甲苯磺酰基取代的底物的反应可取得90%以上的收率.对于重氮和烯基叠氮底物的苯环上含有卤素、甲基和甲氧基等取代基时,反应同样可以顺利进行,以中等收率得到对应产物,电子效应对反应效果影响不大,而存在位阻效应时反应收率略有降低.当降低反应温度或缩短反应时间,可以从反应体系中同时分离得到螺吡咯啉吲哚酮和重氮底物3位乙烯基化的产物.进一步实验表明, 3-烯基吲哚酮可以在标准条件下与烯基叠氮反应,以中等收率得到模板产物.该对照实验表明3-烯基吲哚酮是反应过程中的关键中间体.该反应条件温和,简单高效,底物适用范围广,为构建具有潜在生物活性的螺吲哚酮骨架提供了新的选择. 相似文献
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The mechanism of the dirhodium tetracarboxylate-catalyzed O-H insertion reaction of diazomethane and methyl diazoacetate with
H2O has been studied in detail using DFT calculations. The rhodium catalyst and a diazo compound couple to form a rhodiumcarbene
complex. Of two reaction pathways of the Rh(II)-carbene complex with H2O, the stepwise pathway is more preferable than the concerted one. Formation of a Rh(II) complex-associated oxonium ylide
is an exothermal process, and direct decomposition of the ylide gives a very high barrier. The high barriers for the 1,2-H
shift of Rh(II) complex-associated oxonium ylides make the ylides become stable intermediates in both reactions, especially
for the reactions in solution. Difficulty in formation of a free oxonium ylide supports experimental results, indicating that
the Rh(II) complex-catalyzed nucleophilic addition of a diazo compound proceeds via a Rh(II) complex-associated oxonium ylide rather than via a free oxonium ylide. 相似文献
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A simple and efficient process involving the Rh(II)-catalyzed [1+1+3] annulation of diazooxindoles and vinyl azides has been developed for the synthesis of spiropyrrolidine oxindoles with potential biological activity and significant synthetic applications. This process involves a novel rhodium-catalyzed olefination of diazo compounds, followed by annulation with vinyl azides. This method is compatible with a broad range of substrates and affords moderate to good yields under mild reaction conditions. 相似文献
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[reaction: see text] A series of beta-thio group substituted alpha-diazo carbonyl compounds have been prepared by nucleophilic substitution reactions of thiophenol, thionaphthol, or benzyl mercaptan with beta-acetoxy-alpha-diazo carbonyl compounds. The diazo decomposition of these diazo carbonyl compounds with various transition metal catalysts, including Rh(II) carboxylates and Cu(I) and Cu(II) complexes, has been investigated. It was found that the diazo decomposition of these compounds gave 1,2-thio group migration products. No 1,2-hydride or 1,2-aryl migration products were observed in all cases. 相似文献
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A series of diazo carbonyl compounds bearing different substituents have been prepared in order to investigate the steric effect in 1,2-migration reaction of rhodium(II) carbene. Through the investigation on the diazo decomposition of these compounds with Rh2(OAc)4, it was found that the steric effect could dramatically influence the migratory aptitude. In many cases, the steric effect could override the inherent electronic effect of the substituent. 相似文献
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A convergent approach for the synthesis of diverse N-heterocycles is described. The reaction involves trapping of diazo-derived rhodium carbenoids with gold activated aminoalkynes, and accommodates both the donor/acceptor (D/A) as well as acceptor/acceptor (A/A) diazo carbonyls. Mechanistic investigations indicate that the Rh(II)/Au(I) catalyzed reaction of aminoalkynes with D/A diazos is concerted, while the reaction with A/A diazo is stepwise and proceeds with carbene N–H insertion and a subsequent Conia-ene cyclization. 相似文献
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A series of beta-(N-tosyl)amino diazo carbonyl compounds have been prepared by nucleophilic condensation of N-tosylimines with acyldiazomethanes. The diazo decomposition of these diazo carbonyl compounds under various catalytic conditions, including Rh(II) carboxylates, Cu(I) and Cu(II) complexes, PhCO(2)Ag/Et(3)N, TsOH, and SnCl(2).2H(2)O, has been investigated. It was found that, in most cases, the diazo decomposition gave preferentially 1,2-aryl migration product, but 1,2-hydride migration predominated when PhCO(2)Ag/Et(3)N was the catalytic system. Hammett correlation has been applied in the analysis of the electronic effects of 1,2-aryl migration. The factors that govern the migratory preference and the mechanistic aspects of the reaction are discussed. 相似文献
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This paper reviews the most recent development of [2,3]-sigmatropic rearrangement of sulfur ylide generated from the reaction of sulfide with metal carbene. The metal carbene was formed from decomposition of diazo compounds catalyzed by transition metal complexes such as Cu(I) and Rh(II). 相似文献
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IntramolecularC-HinsertionbyRh(II)-mediatedcarbenoidhasbecomeareactionofconsiderableimportanceinrecentyears'.InadditiontoitsnumeroussyntheticaPplications',therehavebeenextensiveinvestigationsonthemechanismofthisreaction3.AlthoughithasbeengenerallybeIievedthattheC-Hinsertionproceedsthroughaconcertedmechanism,thesuspicionexistSthatradicalorionicpairsndghtbeinvolvedinthereaction.Forexample,DoyIe"andPirrung,'reportedthattheC-HinsertionscatalyzedbyRh2(O2CCF3)4proceededwithstatisticalproduct… 相似文献
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[reaction: see text] Push-pull dipoles generated from the Rh(II)-catalyzed reaction of diazo imides containing tethered heteroaromatic rings undergo successful [3 + 2]-cycloaddition across the 2,3-pi-bond to provide novel pentacyclic compounds in good to excellent yields in a stereocontrolled fashion. The facility of the cycloaddition is critically dependent on conformational factors in the transition state. 相似文献