共查询到18条相似文献,搜索用时 62 毫秒
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综述了近几年铑催化剂在环加成反应中的研究进展, 主要包括[2+2], [2+2+1], [2+2+2], [3+2], [3+4]和[4+2]环加成反应等, 讨论了铑催化下的环加成反应及其机理. 相似文献
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铱催化氧化反应是一种合成含氧有机物的方法.综述了近年来铱催化氧化烃类、醇类、酚类、醚类、醛类、酮类及其它有机物的研究进展,并讨论了部分反应机理. 相似文献
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八元碳环结构广泛存在于天然产物、药物分子(如紫杉醇和瑞他帕林)和香料分子等功能分子中.许多含有八元碳环的天然产物如vinigrol和ophiobolin(蛇孢假壳素)都显示出较好的生物活性.因此,合成这些含有八元碳环的分子将会为药物化学、化学生物学、香料化学、材料化学和其它科学的发展提供分子基础.八元碳环的合成一直是有机合成化学中的挑战之一.为了迎接这一挑战,许多卓有成就的化学家发展出了许多金属催化的环加成反应以合成八元碳环,从而为高效、原子经济性和步骤经济性地合成目标分子提供帮助.在2010年时,我们曾经对利用过渡金属催化的环加成反应制备八元碳环这一前沿方向进行过总结.本综述总结了2010~2020年期间该领域的最新进展,内容包括新型环加成反应的发展、环加成反应的应用以及机理研究,希望可以为关注此领域的有机化学家提供一定的启发和有益的指引,同时鼓励更多合成化学家利用这些环加成反应进行各种功能分子的合成,并发展出更多用于八元碳环合成的高效方法. 相似文献
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铱(Ⅰ)苯乙胺Schiff碱络合物催化苯乙酮的不对称氢转移反应 总被引:1,自引:0,他引:1
以光学活性的苯乙胺和吡啶-2-甲醛缩合而得到的Schiff碱(PPEI)(PPEI=2-「「N-(1-phenylethy)imino」methyl「pyridine中2-「「N-(1-苯乙基)亚胺」甲基「吡啶)为配体,进而与(Ir(COD)Cl」2(COD=1,5环辛二烯)反应,合成了8个光学活性铱铬络合物,考察了它们在异丙醇存在下催化苯乙酮不对称氢转移反应的光学活性,发现「Ir(COD)(PP 相似文献
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尽管铜催化的叠氮和炔烃环加成(CuAAC)反应作为点击化学的核心反应得到广泛应用,然而其不对称催化的研究却相对滞后.反应本身虽然不产生手性元素,但是能够通过对具有潜手性的炔烃或叠氮化合物的去对称化以及外消旋叠氮或炔烃化合物的动力学拆分,来不对称催化合成手性叠氮、炔烃和三氮唑类具有重要应用价值的化合物.自2013年首例高对映选择性的CuAAC反应被报道以来,相关研究有了重要进展,并被成功用于中心手性、轴手性和平面手性的构建.概述了不对称CuAAC反应的研究进展,讨论其面临的发展难题和未来的发展空间. 相似文献
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Mégane Valero Daniel Becker Dr. Kristof Jess Remo Weck Dr. Jens Atzrodt Dr. Thomas Bannenberg Dr. Volker Derdau Prof. Dr. Matthias Tamm 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(26):6517-6522
For the first time, a catalytic protocol for a highly selective hydrogen isotope exchange (HIE) of phenylacetic acid esters and amides under very mild reaction conditions is reported. Using a homogeneous iridium catalyst supported by a bidentate phosphine-imidazolin-2-imine P,N ligand, the HIE reaction on a series of phenylacetic acid derivatives proceeds with high yields, high selectivity, and with deuterium incorporation up to 99 %. The method is fully adaptable to the specific requirements of tritium chemistry, and its effectiveness was demonstrated by direct tritium labeling of the fungicide benalaxyl and the drug camylofine. Further insights into the mechanism of the HIE reaction with catalyst 1 have been provided utilizing DFT calculations, NMR studies, and X-ray diffraction analysis. 相似文献
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Damien Polet Xavier Rathgeb Caroline A. Falciola Jean-Baptiste Langlois Samir El Hajjaji Alexandre Alexakis Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(5):1205-1216
We describe herein the development of the first iridium-catalyzed allylic substitution using arylzinc nucleophiles. High enantioselectivities were obtained from the reactions, which used commercially available Grignard reagents as the starting materials. This methodology was also shown to be compatible with halogen/metal exchange reactions. Its synthetic potential is demonstrated by its application towards the formal synthesis of (+)-sertraline. 相似文献
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Tingting Wang Changmeng Liu Dong Xu Jiaxi Xu Zhanhui Yang 《Molecules (Basel, Switzerland)》2022,27(22)
A highly chemoselective conversion of α,β-disubstituted nitroalkenes to ketones is developed. An acid-compatible iridium catalyst serves as the key to the conversion. At a 2500 S/C ratio, nitroalkenes were readily converted to ketones in up to 72% isolated yields. A new mechanistic mode involving the reduction of nitroalkene to nitrosoalkene and N-alkenyl hydroxylamine is proposed. This conversion is ready to amplify to a gram-scale synthesis. The pH value plays an indispensable role in controlling the chemoselectivity. 相似文献
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Trumping DIBALH: A new method for reduction of esters to aldehydes through silyl acetal intermediates involves a single-step hydrosilylation catalyzed by a readily available iridium complex, [{Ir(coe)(2) Cl}(2) ] (see scheme; coe=cyclooctene). The low catalyst loading, mild reaction conditions, high conversions, and broad substrate scope make this method a superior alternative to ester reduction using DIBALH. 相似文献
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Dr. Simon Wübbolt Dr. Choon Boon Cheong Dr. James R. Frost Dr. Kirsten E. Christensen Prof. Dr. Timothy J. Donohoe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11435-11440
A vinyl cyclopropane rearrangement embedded in an iridium-catalyzed hydrogen borrowing reaction enabled the formation of substituted stereo-defined cyclopentanes from Ph* methyl ketone and cyclopropyl alcohols. Mechanistic studies provide evidence for the ring-expansion reaction being the result of a cascade based on oxidation of the cyclopropyl alcohols, followed by aldol condensation with the pentamethyl phenyl-substituted ketone to form an enone containing the vinyl cyclopropane. Subsequent single electron transfer (SET) to this system initiates a rearrangement, and the catalytic cycle is completed by reduction of the new enone. This process allows for the efficient formation of diversely substituted cyclopentanes as well as the construction of complex bicyclic carbon skeletons containing up to four contiguous stereocentres, all with high diastereoselectivity. 相似文献
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Dr. Yao Ge Dr. Zheng Wang Dr. Zhaobin Han Prof. Dr. Kuiling Ding 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15482-15486
Enantioselective hydrogenation of a broad spectrum of N-, O-, and S-containing aromatic benzoheterocycles or nonaromatic unsaturated heterocycles has been realized by using an Ir/SpinPHOX (SpinPHOX=spiro[4,4]-1,6-nonadiene-based phosphine-oxazoline) complex as the catalyst, affording an array of the corresponding chiral benzoheterocycles (30 examples) with excellent enantioselectivities (>99 % ee in most cases) and turnover numbers up to 500. 相似文献
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Xingyu Jiang Prof. John F. Hartwig 《Angewandte Chemie (International ed. in English)》2017,56(30):8887-8891
Enantioselective allylic substitution with enolates derived from aliphatic esters under mild conditions remains challenging. Herein we report iridium-catalyzed enantioselective allylation reactions of silyl ketene acetals, the silicon enolates of esters, to form products containing a quaternary carbon atom at the nucleophile moiety and a tertiary carbon atom at the electrophile moiety. Under relatively neutral conditions, the allylated aliphatic esters were obtained with excellent regioselectivity and enantioselectivity. These products were readily converted into primary alcohols, carboxylic acids, amides, isocyanates, and carbamates, as well as tetrahydrofuran and γ-butyrolactone derivatives, without erosion of enantiomeric purity. 相似文献