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含茂基稀土金属有机络合物催化剂在有机合成中的应用 总被引:2,自引:0,他引:2
综述了含茂基稀土金属有机络合物催化下的不饱和烃(或其取取衍生物)转化反应及其在有机合成中的作用。重点阐述了含茂基稀土金属有机络合物催化的烯烃氧化,氢化环化;烯烃和炔烃的氢化硅化,1,5-或1,6-二烯或烯炔的氢化硅化/环化,氨基取代烯烃,炔烃,丙二烯等的氢化胺化/环化等反应在有机合成中的主要用途,这些反应在形成碳-杂原子键,碳-碳键,碳环和杂环等方面具有广泛的应用前景。讨论了这些反应的催化循环机制,区域稳定性,对映选择性,非对映选择性及其影响因素。 相似文献
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碳环化合物,特别是五元环和六元环骨架,广泛存在于天然产物和生物活性分子中.Diels-Alder环加成反应是构建这些功能型分子的有效方法,但其底物适用范围有限,且反应条件(如热、微波和过渡金属的使用)苛刻,限制了该方法的应用.自由基物种含有不成对的价电子,表现出高活性,在温和的反应条件下提供了新的反应途径.因此,自由基介导的反应为复杂环状分子的合成提供了一个新平台.然而,如何实现选择性自由基环化仍然是一个挑战.鲍德温规则为自由基物种与烯烃炔烃的加成提供了指导,研究人员设计并开发了一系列反应模式构建所需的五元和六元环分子.但是,自由基物种,特别是烷基和烯基与芳基之间选择性的邻位原位环化仍然不明确.本文利用苄基丙二酸酯为自由基源,烯烃和炔烃分别为自由基受体,分别获得烷基和烯基自由基中间体,并探究烷基自由基和烯基自由基与芳基之间的选择性环化.利用二茂铁介导的电化学氧化策略,进行了烷基/烯基自由基与芳基的选择性环化实验.结果表明,烷基自由基与芳环发生选择性邻位-(4+2)环化,烯基自由基与芳环发生选择性原位-(3+2)环化.理论研究结果表明,促进烯烃优先邻位加成的主要原因是有利的相互作用能;炔... 相似文献
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结合本研究小组的相关课题工作,综述了苯乙烯内酯类天然产物全合成方法的 研究进展。主要包括以呋喃甲醇类化合物的氧化重排反应、烯烃复分解环化反应( RCM)和酸催化的酯化关环等作为关键反应的方法。 相似文献
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从柠檬醛出发,经环化、氰基化、烯丙位氧化、水解及环化还原等5步反应,合成了(±)-耳壳藻内酯(1)。 相似文献
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微波技术在有机合成中的应用 总被引:48,自引:1,他引:48
评述了微波加热技术在有机合物的烃基化,酯化和皂化,磺化,烯烃加成,Diels-Alder缩合,氧化,环化与开环及重排等反应中的应用,参考文献73篇。 相似文献
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Environmentally benign radical carboaminoxylations of various nonactivated olefins and difficult radical cyclization reactions are performed in good to excellent yields and with short reaction times under microwave irradiation. 相似文献
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Yoshikai K Hayama T Nishimura K Yamada K Tomioka K 《The Journal of organic chemistry》2005,70(2):681-683
Thiol-catalyzed direct generation of acyl radicals and their intramolecular addition to olefins of alkenals gave 2-substituted five- and six-membered cyclic ketones in reasonably good yields. The combination of odorless tert-dodecanthiol and AIBN or V-40 was the initiator of choice among surveyed radical generators for the cyclization of alkenals. Aldehydes having electron-deficient olefins cyclized more easily than those having unactivated olefins. 相似文献
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[reaction: see text] We present a new "conjunctive" radical cyclization process that involves the reaction of a 1,6-diene with the Tordo alkoxyamine, an agent originally developed for the radical polymerization of certain olefins through the "persistent radical effect". 相似文献
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A new operationally simple and robust protocol for the metal-free atom transfer radical reaction (ATRA) has been developed. Polychlorinated compounds were effectively reacted with unactivated terminal olefins to generate 1,3-dichlorinated adducts under microwave irradiation in the presence of silicon carbide (SiC) as a heating element. The present microwave-assisted ATRA proceeds under essentially neutral conditions; thus, polar functionalities are well tolerated. In addition, an oxygen or a nitrogen unit was introduced to the internal side of the carbon chain via nucleophilic cyclization of the 1,3-dichlorinated adducts, and single-step formation of the six-membered carbocycle was realized through cyclization of the intermediate radical. The present methodology provides an expeditious way to prepare synthetically useful molecules from simple and unactivated terminal olefins. 相似文献
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《Comptes Rendus de l''Academie des Sciences Series IIB Mechanics Physics Astronomy》2001,4(7):539-546
The synthetic utility of 1,1,2,2-tetraphenyldisilane as a new, environmentally benign radical mediator is discussed for the reduction, cyclization, reductive addition to olefins, and alkylation of heteroaromatic bases. 相似文献
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Tin-free radical sequences under acidic conditions. Convergent access to azole-containing structures
[reaction: see text] Various xanthates add efficiently to olefins bearing [1,2,4]triazole, imidazole, or benzimidazole moieties in the presence of camphorsulfonic acid via a radical chain reaction initiated by a small amount of lauroyl peroxide. The adducts may be transformed to more complex molecules by implementing a further radical cyclization. 相似文献
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Shubham Dutta Rajendra K. Mallick Rangu Prasad Vincent Gandon Akhila K. Sahoo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2311-2316
Ynamides are typically more reactive than simple alkynes and olefins. However, a serendipitous observation revealed a rare case where the reactivity of simple alkynes exceeds that of ynamides. This led to the development of a unique sulfur‐radical‐triggered cyclization of yne‐tethered ynamides, which involves attack of the alkyne by a thiyl radical followed by cyclization with the ynamide. A wide range of novel 4‐thioaryl pyrroles that could tolerate common functional moieties and N‐protecting groups were expediently constructed by this strategy. The current method contrasts with the typical cyclization of yne‐ynamides, which involves the attack of the alkyne moiety by the ynamide core. Control experiments and DFT calculations supported the participation of the sulfur radical in the reaction and the regioselective cyclization. The synthetic potential of the substituted pyrroles is also discussed. 相似文献
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Feili Tang 《Tetrahedron》2009,65(52):10863-635
The cyclization chemistry of radical cations derived from electron-rich olefins has been examined and the relationship between the polarization of the radical cation and the chemoselectivity of the reaction probed. It was found that more polarized radical cations favor carbon-carbon bond formation while less polarized radical cations favor carbon-heteroatom bond formation. A new approach to the synthesis of quaternary carbons was uncovered and the compatibility of ene diol ethers with anodic olefin coupling reactions examined. 相似文献
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Markus R. Heinrich 《Tetrahedron letters》2007,48(22):3895-3900
The oxidative radical cyclization of α-fluoroacetophenones in the presence of olefins offers an efficient access to 2-fluorotetralones. Fluorinated starting materials can be prepared from α-bromoacetophenones. The reaction was optimized with respect to a future application in the synthesis of 18-fluorine labeled compounds, where reaction times are a critical aspect. 相似文献