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Xianjin Wang Xin Cui Sida Li Yue Wang Chungu Xia Haijun Jiao Lipeng Wu 《Angewandte Chemie (International ed. in English)》2020,59(32):13608-13612
A general and atom‐economical synthesis of 1,1‐diborylalkanes from alkenes and a borane without the need for an additional H2 acceptor is reported for the first time. The key to our success is the use of an earth‐abundant zirconium‐based catalyst, which allows a balance of self‐contradictory reactivities (dehydrogenative boration and hydroboration) to be achieved. Our method avoids using an excess amount of another alkene as an H2 acceptor, which was required in other reported systems. Furthermore, substrates such as simple long‐chain aliphatic alkenes that did not react before also underwent 1,1‐diboration in our system. Significantly, the unprecedented 1,1‐diboration of internal alkenes enabled the preparation of 1,1‐diborylalkanes. 相似文献
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Xiaogen Huang Dr. Teresa de Haro Cristina Nevado Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(24):5904-5908
Change the ligand, change the stereochemistry : 2,3‐Bis(acetoxy)‐1,3‐dienes are obtained in a stereocontrolled manner by a novel tandem 1,2‐/1,2‐bis(acetoxy) rearrangement (see scheme, R1 and R2 are δ+ stabilizing). Upon stabilization of the reaction intermediates, the ligand attached to gold controls the stereochemistry of the alkene in the second acetate migration, that is, N‐heterocyclic carbenes (NHC) favor cis alkenes, whereas phosphine ligands selectively afford trans olefins.
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Qiufeng Huang Dr. Ruimao Hua Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(15):3817-3822
Economical atoms : 2‐Cyclopenten‐1‐ones, 5‐alkylidenefuran‐2(5 H)‐ones and indan‐1‐ones have been synthesized by atom‐economic reductive cyclocarbonylation of internal alkynes with carbon monoxide catalyzed by [{RhCl(CO)2}2]/CO(NH2)2 in the presence of water (see scheme).
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José Barluenga Prof. Dr. Abraham Mendoza Félix Rodríguez Dr. Francisco J. Fañanás Dr. 《Angewandte Chemie (International ed. in English)》2009,48(9):1644-1647
Functionalized spiroacetals have been easily prepared in a one‐pot three‐component coupling process that involves the reaction of pentynol derivatives, salicylaldehydes, and amines in the presence of catalytic amounts of a palladium(II) complex (see scheme). Alternatively, oxygen‐substituted spiroacetals can be obtained by using orthoesters as the third component.
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Ji‐Qian Wu Bai‐Xiang Li Sen‐Wang Zhang Yue‐Sheng Li 《Journal of polymer science. Part A, Polymer chemistry》2010,48(14):3062-3072
Bis(β‐enaminoketonato) vanadium(III) complexes ( 2a–c ) [O(R1)C?C(H)xC(R2)?NC6H5]2VCl(THF) and the corresponding vanadium(IV) complexes ( 3a–c ) [O(R1)C?C(H)xC(R2)? NC6H5]2VO (R1 = ? (CH2)4? , R2 = H, x = 0, a ; R1 = ? C6H5, R2 = H, x = 1, b ; R1 = ? C6H5, R2 = ? C6H5, x = 1, c ) have been synthesized from VCl3(THF)3 and VOCl2(THF)2, respectively, by treating with 2.0 equivalent β‐enaminoketonato ligands in tetrahydrofuran. Structures of 2b and 3a–c were further confirmed by X‐ray crystallographic analysis. The complexes were investigated as the catalysts for ethylene polymerization in the presence of Et2AlCl. Complexes 2a–c and 3a–c exhibited high catalytic activities (up to 23.76 kg of PE/mmolV h bar), and afforded polymers with unimodal molecular weight distributions at 70 °C indicating the good thermal stability. The catalytic behaviors were influenced not only by the oxidation state of the catalyst precursors but also by the ligand structures. Complexes 2a–c and 3a–c were also effective catalyst precursors for ethylene/1‐hexene copolymerization. The influence of polymerization parameters such as reaction temperature, Al/V molar ratio and hexene feed concentration on the ethylene/hexene copolymerization behaviors have bee also investigated in detail. In addition, the agents such as AlMe3, AliBu3, MeMgBr, MgCl2, and ZnEt2 were applied to control the molecular weight and molecular weight distribution modal. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3062–3072, 2010 相似文献
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Stereocontrolled Synthesis of Vinyl Boronates and Vinyl Silanes via Atom‐Economical Ruthenium‐Catalyzed Alkene–Alkyne Coupling 下载免费PDF全文
Prof. Dr. Barry M. Trost Dr. Dennis C. Koester Alastair N. Herron 《Angewandte Chemie (International ed. in English)》2015,54(52):15863-15866
The synthesis of vinyl boronates and vinyl silanes was achieved by employing a Ru‐catalyzed alkene–alkyne coupling reaction of allyl boronates or allyl silanes with various alkynes. The double bond geometry in the generated vinyl boronates can be remotely controlled by the juxtaposing boron‐ and silicon groups on the alkyne substrate. The synthetic utility of the coupling products has been demonstrated in a variety of synthetic transformations, including iterative cross‐coupling reactions, and a Chan‐Lam‐type allyloxylation followed by a Claisen rearrangement. A sequential one‐pot alkene‐alkyne‐coupling/allylation‐sequence with an aldehyde to deliver a highly complex α‐silyl‐β‐hydroxy olefin with a handle for further functionalization was also realized. 相似文献
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David J. Liptrot Professor Michael S. Hill Dr. Mary F. Mahon 《Angewandte Chemie (International ed. in English)》2014,53(24):6224-6227
Reactions of TEMPO (2,2,6,6‐tetramethyl‐1‐piperidinyloxy) with magnesium hydride species initiate oxidative hydrogen release, which may be elaborated to a catalytic regime within a manifold constructed about sequential TEMPO‐mediated redox and Mg? O/Si? H metathesis processes. 相似文献
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Kenichi Nomura Seijiro Matsubara Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(2):703-708
A novel rearrangement of 2‐(1‐hydroxyalkyl)‐1‐alkylcyclopropanol has been found. It proceeds in the presence of a catalytic amount of organozinc ate complex to give vic‐diols. The rearrangement can be applied to various types of 2‐(1‐hydroxyalkyl)‐1‐alkylcyclopropanol, which can be easily prepared from the corresponding α,β‐epoxyketones and bis(iodozincio)methane. When bicyclo[13.1.0]pentadecane‐1,15‐diol was treated with the organozinc ate complex, the corresponding 14‐membered cyclic vic‐diol was obtained. Thus, this rearrangement is also useful for changing the ring size of cyclic substrates. 相似文献
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Alexis Coste Ganesan Karthikeyan Dr. François Couty Prof. Gwilherm Evano Dr. 《Angewandte Chemie (International ed. in English)》2009,48(24):4381-4385
Mild reaction conditions are the advantage of the title reaction, which allows straightforward entry to a variety of ynamides starting from readily available 1,1‐dibromo‐1‐alkenes, which act as attractive alkynylating agents (see scheme; EWG=electron‐withdrawing group, DMF=N,N‐dimethylformamide).
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Ziba Khodaee Asieh Yahyazadeh Nosrat O. Mahmoodi 《Journal of heterocyclic chemistry》2013,50(2):288-292
The synthesis and structural elucidation of some novel 5,5′‐disubstituted spiro and nonspiro‐bis‐hydantoins are reported. The Bucherer Burge's method has been modified for the preparation of some 5,5′‐substituted bis(imidazolidine‐2,4‐dione) derivatives starting with diketones ( 1–5 ) and dialdehydes ( 6 , 7 ). In some cases, diastereoisomeric mixtures of compounds were obtained. The resulting bis‐hydantoins ( 8–11 , 13 , 14 ) have not to our knowledge been previously reported in the literature. 相似文献
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Dr. Srijit Biswas Dr. Christian Dahlstrand Rahul A. Watile Dr. Marcin Kalek Prof. Dr. Fahmi Himo Prof. Dr. Joseph S. M. Samec 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(52):17939-17950
Gold(I)‐chloride‐catalyzed synthesis of α‐sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols showed a wide substrate scope with respect to both propargylic alcohols and aryl thiols. Primary and secondary aromatic propargylic alcohols generated α‐sulfenylated aldehydes and ketones in 60–97 % yield. Secondary aliphatic propargylic alcohols generated α‐sulfenylated ketones in yields of 47–71 %. Different gold sources and ligand effects were studied, and it was shown that gold(I) chloride gave the highest product yields. Experimental and theoretical studies demonstrated that the reaction proceeds in two separate steps. A sulfenylated allylic alcohol, generated by initial regioselective attack of the aryl thiol on the triple bond of the propargylic alcohol, was isolated, evaluated, and found to be an intermediate in the reaction. Deuterium labeling experiments showed that the protons from the propargylic alcohol and aryl thiol were transferred to the 3‐position, and that the hydride from the alcohol was transferred to the 2‐position of the product. Density functional theory (DFT) calculations showed that the observed regioselectivity of the aryl thiol attack towards the 2‐position of propargylic alcohol was determined by a low‐energy, five‐membered cyclic protodeauration transition state instead of the strained, four‐membered cyclic transition state found for attack at the 3‐position. Experimental data and DFT calculations supported that the second step of the reaction is initiated by protonation of the double bond of the sulfenylated allylic alcohol with a proton donor coordinated to gold(I) chloride. This in turn allows for a 1,2‐hydride shift, generating the final product of the reaction. 相似文献
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A Bis(silylene)‐Substituted ortho‐Carborane as a Superior Ligand in the Nickel‐Catalyzed Amination of Arenes 下载免费PDF全文
Yu‐Peng Zhou Dr. Saeed Raoufmoghaddam Dr. Tibor Szilvási Prof. Dr. Matthias Driess 《Angewandte Chemie (International ed. in English)》2016,55(41):12868-12872
The synthesis and structure of the first 1,2‐bis(NHSi)‐substituted ortho‐carborane [(LSi:)C]2B10H10 (termed SiCCSi) is reported (NHSi=N‐heterocyclic silylene; L=PhC(NtBu)2). Its suitability to serve as a reliable bis(silylene) chelating ligand for transition metals is demonstrated by the formation of [SiCCSi]NiBr2 and [SiCCSi]Ni(CO)2 complexes. The CO stretching vibration modes of the latter indicate that the SiII atoms in the SiCCSi ligand are even stronger σ donors than the PIII atoms in phosphines and CII atoms in N‐heterocyclic carbene (NHC) ligands. Moreover, the strong donor character of the [SiCCSi] ligand enables [SiCCSi]NiBr2 to act as an outstanding precatalyst (0.5 mol % loading) in the catalytic aminations of arenes, surpassing the activity of previously known molecular Ni‐based precatalysts (1–10 mol %). 相似文献
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Gold(I)‐Catalyzed Diazo Cross‐Coupling: A Selective and Ligand‐Controlled Denitrogenation/Cyclization Cascade 下载免费PDF全文
Guangyang Xu Chenghao Zhu Dr. Weijin Gu Dr. Jian Li Prof. Dr. Jiangtao Sun 《Angewandte Chemie (International ed. in English)》2015,54(3):883-887
An unprecedented gold‐catalyzed ligand‐controlled cross‐coupling of diazo compounds by sequential selective denitrogenation and cyclization affords N‐substituted pyrazoles in a position‐switchable mode. This novel transformation features selective decomposition of one diazo moiety and simultaneous preservation of the other one from two substrates. Notably, the choice of the ancillary ligand to the gold complex plays a pivotal role on the chemo‐ and regioselectivity of the reactions. 相似文献
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1,4-双(2,4-二羟基苯基)丁二酮-1,4-是Prakash等从买麻藤属龈(GenehumULa)中分离得到的一种微量组分。文中报道了以丁二腈和间苯二酚为原料,“一锅法”简便合成了此化合物。 相似文献