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过渡金属催化的烯丙基取代反应是一类重要且实用的有机化学反应, 可以立体选择性地高效构建碳-碳键和碳-杂键. 可见光氧化还原催化可以利用绿色清洁的可见光能源在较为温和的条件下产生自由基或者自由基离子等高反应活性的反应中间体, 被广泛地应用于有机合成中, 逐渐发展成为一种重要的合成工具. 鉴于烯丙基取代反应的重要性, 过渡金属与光氧化还原协同催化的烯丙基取代反应逐渐引起化学家的兴趣. 该协同催化的策略可以实现单一过渡金属催化难以实现的烯丙基取代反应, 反应的区域选择性和立体选择性也体现出不同的特点, 有望发展成为单一金属催化的烯丙基取代反应的重要补充. 本文综述了近年来不同过渡金属与可见光氧化还原协同催化的烯丙基取代反应的研究进展. 相似文献
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烯丙基磷叶立德(allylic phosphorus ylides)是一类具有丰富反应性的有机中间体.由于碳负离子离域,烯丙基磷叶立德可通过γ位碳负离子参与亲核进攻,从而实现vinylogous(插烯)类型有机合成反应.综述了烯丙基磷叶立德与羰基化合物的vinylogous类型反应,具体包括vinylogous Wittig烯化反应以及多种环化反应.这些反应拓展了烯丙基磷叶立德在有机合成中的应用,并提供构筑多种重要有机功能分子的新方法. 相似文献
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本文应用程序升温脱附和程序升温反应技术,对镍基催化剂上CO 的吸附和歧化及其同水的反应进行了研究。结果表明:随吸附温度的升高,(从120℃到300℃)CO 的解离吸附不断增加。400℃以上助剂中的氧参与了表面碳的氧化,在多层积碳的表面上,CO 仍然能够被吸附和进行歧化反应,表明表面碳可能代替镍起到CO吸附和反应的新的活性中心的作用。在高温陈化过的表面碳上,CO 吸附困难。CO与水的反应很可能是以表面碳做为反应中间体进行的。同水反应的表面碳有三种形态,其反应峰温分别为246℃、360—370℃和>550℃。520℃陈化后,前两种形态的表面碳失活严重,而后一种则比较稳定。 相似文献
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金属铟在空气中不会被氧化,在水中也很稳定,而且无毒,易被制成各种铟盐和有机铟试剂并参与化学反应。铟盐与其他Lewis酸相比也具有良好的水相稳定性。由于铟具有低的亲杂性,在反应过程中大多数官能团都不受影响,因而铟试剂成为有机合成中常用的导向试剂,受到了人们极大的关注。本文综述了近年来金属铟、铟盐及有机铟试剂参与的水相化学反应,介绍了铟试剂促进的一些新型反应的特点和优势及在有机合成中的应用,总结了水相中铟试剂参与化学反应的最新进展,提出了铟试剂今后研究和发展的重点和方向。 相似文献
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本文综述了近10 年来手性二茂铁类配体在钯催化不对称烯丙基取代反应,包括各种不同底物的烯丙基烷基化、烯丙基胺基化和烯丙基磺酰化反应中的应用,并对其在不对称Claisen 重排、不对称Diels-Alder 反应、不对称Heck 反应、不对称羰基化、不对称氢化硅烷化和不对称碳碳键断裂等反应中的应用进行了综述,对部分反应的机理和该领域的发展前景进行了讨论。 相似文献
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Albert T. H. Bartholomäus Dávid Roman Walid K. Al-Jammal Prof. Dr. Ivan Vilotijević Prof. Dr. Christine Beemelmanns 《European journal of organic chemistry》2023,26(18):e202300177
The formation of C−C bonds via the allylation of carbonyl compounds has been widely applied in total syntheses. Amongst the many possible strategies, the Barbier-type allylation in aqueous media has received only moderate attention over the last decades despite its mild reaction conditions. In this study, we investigated the indium (In0) and zinc (Zn0) mediated Barbier allylation reaction to efficiently synthesize base-labile 3-methylene-5-hydroxy containing building blocks for natural product total synthesis. As model study we selected the allylation of lipidic undecanal with ethyl 3-(bromomethyl)but-3-enoate in the presence of either Zn0 or In0 and investigated the effects of additives on yields and selectivities. We then applied the optimized reaction conditions to sterically demanding allyl bromides and functionalized aromatic aldehydes yielding eleven new homoallylic alcohols, one of which was further transformed via oxidation and reduction sequences. 相似文献
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Aldehydes undergo preferential allylation in the presence of ketones by the tin or zinc mediated method, easily effected in aqueous media. 相似文献
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[reaction: see text] Highly regio- and stereoselective allylation of aldehydes by allenes proceeds smoothly in aqueous/organic media in the presence of PdCl(2)(PPh(3))(2), HCl, and SnCl(2). The reaction likely occurs via hydrostannylation of allenes and allylation of aldehydes by the in situ generated allyltrichlorotins to afford the final products. 相似文献
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Jie Eun Lee Joo Hwan Cha Ae Nim Pae Kyung II Choi Hun Yeong Koh Youseung Kim 《合成通讯》2013,43(23):4299-4308
Allylation of the C-3 position of the cephem nucleus was accomplished by either indium mediated or indium trichloride promoted tin mediated allylation reactions in aqueous media. Both methods gave 3-allyl-3-hydroxycephams 2a - 2d, in moderate to excellent yields. 相似文献
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Iminium ions, generated in aqueous solution from secondary amines and formaldehyde, undergo a Barbier-type allylation mediated by tin, aluminum and zinc. The reaction is catalyzed by copper and produces tertiary homoallylamines in up to 85% yield. 相似文献
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Balin Kumar BhuyanArun Jyoti Borah Kula Kamal SenapatiProdeep Phukan 《Tetrahedron letters》2011,52(21):2649-2651
Titanium exchanged ZSM-5 catalyst has been prepared by treating an aqueous solution of titanium (IV) chloride with ZSM-5. The supported catalyst has been explored as effective and reusable catalyst for allylation reaction of aldehydes with allyltributylstannane. The new catalytic system promotes efficiently the allylation reaction in toluene condition to produce homoallylic alcohols in high yield. 相似文献
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Tak Chung Chan 《Tetrahedron letters》2004,45(21):4189-4191
Iron metal was found to be able to mediate the allylation reaction of aryl aldehydes in aqueous media with sodium fluoride as the promoter. The possible implication of an allyliron intermediate was examined. 相似文献
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Prof. Dr. Shū Kobayashi Toshimitsu Endo Takumi Yoshino Dr. Uwe Schneider Dr. Masaharu Ueno 《化学:亚洲杂志》2013,8(9):2033-2045
Zn(OH)2‐catalyzed allylation reactions of aldehydes with allylboronates in aqueous media have been developed. In contrast to conventional allylboration reactions of aldehydes in organic solvents, the α‐addition products were obtained exclusively. A catalytic cycle in which the allylzinc species was generated through a B‐to‐Zn exchange process is proposed and kinetic studies were performed. The key intermediate, an allylzinc species, was detected by HRMS (ESI) analysis and by online continuous MS (ESI) analysis. This analysis revealed that, in aqueous media, the allylzinc species competitively reacted with the aldehydes and water. An investigation of the reactivity and selectivity of the allylzinc species by using several typical allylboronates ( 6a , 6b , 6c , 6d ) clarified several important roles of water in this allylation reaction. The allylation reactions of aldehydes with allylboronic acid 2,2‐dimethyl‐1,3‐propanediol esters proceeded smoothly in the presence of catalytic amounts of Zn(OH)2 and achiral ligand 4d in aqueous media to afford the corresponding syn‐adducts in high yields with high diastereoselectivities. In all cases, the α‐addition products were obtained and a wide substrate scope was tolerated. Furthermore, this reaction was applied to asymmetric catalysis by using chiral ligand 9 . Based on the X‐ray structure of the Zn‐ 9 complex, several nonsymmetrical chiral ligands were also found to be effective. This reaction was further applied to catalytic asymmetric alkylallylation, chloroallylation, and alkoxyallylation processes and the synthetic utility of these reactions has been demonstrated. 相似文献
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Stereoselective allylation reactions of acyclic, chiral α-amino-β-hydroxy aldehydes containing four contiguous stereocenters were conducted. Allylation mediated by MgBr2?OEt2 afforded the anti-product. A plausible mechanism of the allylation reaction is also described. The resulting allylation product was used for the total synthesis of (+)-1-epi-castanospermine. 相似文献
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Catalyzed by PdCl2, SnCl2 can efficiently mediate the allylation of various aldehydes with allyl chloride or bromide, but not with allyl alcohol, in fully aqueous media. The yield of the reaction is very high (90-100%), and the reaction is operationally simple, environmental benign and easy to scale up. 相似文献