共查询到20条相似文献,搜索用时 15 毫秒
1.
Yoshiaki Nakao 《Tetrahedron》2006,62(32):7567-7576
A nickel catalyst prepared from Ni(cod)2 and PMe3 is found to effect arylcyanation reaction of alkynes, namely, cleavage of a C-CN bond of an aryl cyanide followed by addition of each fragment across an alkyne. A wide range of functional groups in aryl cyanides tolerated the catalysis, giving variously functionalized β-arylalkenenitriles stereoselectively. 相似文献
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Hung A. Duong 《Journal of organometallic chemistry》2005,690(23):5098-5104
The regioselectivity of Ni(0)-catalyzed cycloadditions of various isocyanates and asymmetrical alkynes to afford pyridones was explored. The use of PEt3 provided, in most cases, two of the four possible pyridone regioisomers in high overall yields. Mechanistic rationale for the product distribution is provided. 相似文献
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Alkynyl cyanides are found to add across alkynes and 1,2-dienes in the presence of a catalyst prepared in situ from Ni(cod)2, xantphos, and BPh3. A range of functionalized conjugated cis-enynes are obtained with high regioselectivity. The addition reaction across norbornadiene proceeds in the absence of BPh3 to give exo-cis adduct exclusively. A stoichiometric reaction of an alkynyl cyanide, Ni(cod)2, xantphos, and BPh3 gives trans-(xantphos)Ni(CNBPh3)(CCSiMe2t-Bu), which is suggested to be a plausible reaction intermediate of the alkynylcyanation reaction. 相似文献
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[reaction: see text]. Addition of dialkyl disulfides to terminal alkynes is catalyzed by a rhodium-phosphine complex and trifluoromethanesulfonic acid giving (Z)-bis(alkylthio)olefins stereoselectively. 相似文献
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The silver catalysis towards the hydration of terminal alkynes is explored using Silver(I) triflate (AgOTf). The reaction leads to the formation of only Markovnikov addition product with excellent yield. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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The addition of terminal alkynes to aromatic aldehydes was carried out under mild conditions in the presence of a Cu-phosphine complex, which was prepared in situ from Cu(O-t-Bu) and TRAP chiral bisphosphine, to yield enantiomerically enriched propargyl alcohols with moderate enantioselectivities. Furthermore, according to stoichiometric reactions, the reaction presumably involves the addition of a TRAP-coordinated Cu(I) acetylide to an aldehyde. 相似文献
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A palladium dimer with a cobalt-containing phosphine ligand, {(μ-PPh2CH2PPh2)Co2(CO)4(μ,η-(tBu)2PCCC6H4-κC1)Pd(μ-Cl)}2 (3), was prepared from the reaction of its monomer precursor, (μ-PPh2CH2PPh2)Co2(CO)4(μ,η-(tBu)2PCCC6H4-κC1)Pd(μ-OAc) (2), with LiCl. The crystal structure of 3, determined by X-ray diffraction methods, revealed a doubly chloride-bridged palladium dimeric conformation. Suzuki coupling reactions of bromobenzene with phenylboronic acid were carried out catalytically using these two novel palladium complexes 2 and 3 as catalyst precursors. Factors such as the molar ratio of substrate/catalyst, reaction temperature, base and solvent that might affect the catalytic efficiencies were investigated. As a general rule, the performance is much better by employing 3 than 2 as the catalyst precursor. 相似文献
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Three bulky mono-dentate alkyne-bridged dicobalt-phosphine complexes [(μ-PPh2CH2PPh2)Co2(CO)4](μ,η-PhCCPPh2) 4a, [(μ-PPh2CH2PPh2)Co2(CO)4](μ,η-Me3CCCPPh2) 5a and [(μ-PPh2CH2PPh2)Co2(CO)4](μ,η-Me3SiCCPPh2) 6a were prepared from the reactions of the bis(diphenylphosphino)methylene (dppm) bridged dicobalt complex Co2(CO)6(μ-Ph2PCH2PPh2) with PhCCPPh21, Me3CCCPPh22, and Me3SiCCPPh23, respectively. These three metal-containing compounds 4a, 5a and 6a were employed as ligands, replacing conventional organic phosphines, in the Suzuki cross-coupling reactions and have been proved to be effective, authentic mono-dentate phosphine ligands. 相似文献
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C Gunanathan M Hölscher F Pan W Leitner 《Journal of the American Chemical Society》2012,134(35):14349-14352
The nonclassical ruthenium hydride pincer complex [Ru(PNP)(H)(2)(H(2))] 1 (PNP = 1,3-bis(di-tert-butyl-phosphinomethyl)pyridine) catalyzes the anti-Markovnikov addition of pinacolborane to terminal alkynes yielding Z-vinylboronates at mild conditions. The complex [Ru(PNP)(H)(2)(HBpin)] 2 (HBpin = pinacolborane), which was identified at the end of the reaction and prepared independently, is proposed as the direct precursor to the catalytic cycle involving rearrangement of coordinated alkyne to Z-vinylidene as a key step for the apparent trans-hydroboration. 相似文献
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Regioselective enol ester formation results from the addition of saturated and unsaturated carboxylic acids to phenylacetylene in the presence of RuCl3, RuCl3/2PR3 or RuCl2(PMe2)(arene) catalysts. 相似文献
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Komeyama K Sasayama D Kawabata T Takehira K Takaki K 《Chemical communications (Cambridge, England)》2005,(5):634-636
Rare-earth silylamide complexes, Ln[N(SiMe3)2]3 (Ln = Y, La, Sm, Yb), effectively catalyzed the coupling reaction of isocyanides with both aliphatic and aromatic terminal alkynes under mild conditions. 相似文献
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Polymerization of optically active disubstituted acetylene monomers by Pd catalyst bearing bulky phosphine ligand 下载免费PDF全文
Yuta Goto Yu Miyagi Natsuhiro Sano Fumio Sanda 《Journal of polymer science. Part A, Polymer chemistry》2017,55(18):3011-3016
Chloro- and aryl-substituted acetylene monomers having an optically active group were polymerized by a Pd catalyst [(tBu3P)PdMeCl] bearing a bulky phosphine ligand, and by MoCl5 for comparison. The corresponding disubstituted acetylene polymers with Mn's = 2000–19,500 and 6900–10,800 were obtained in 29–83% and 11–62% yields when the Pd and Mo catalysts were used, respectively. The formation of polyacetylenes, poly[(R)- 1p ], poly[(R)- 1m ], and poly[(S)- 2p ] were confirmed by SEC and the presence of a Raman scattering peak based on the alternating double bonds of the main chain. Pd-based poly[(R)- 1m ] exhibited CD signals around 350 nm assignable to a certain secondary structure, while Mo-based poly[(R)- 1m ] did not. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3011–3016 相似文献
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The first direct intermolecular hydroamination/hydroalkylation of terminal alkynes catalyzed by In(OTf)(3) under one-pot conditions leading to the formation of conjugated ketimines in good yields is described. 相似文献
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Midya GC Paladhi S Dhara K Dash J 《Chemical communications (Cambridge, England)》2011,47(23):6698-6700
Iron can catalyze head-to-head dimerization of terminal aryl alkynes to give the corresponding (E) selective conjugated enynes in high yields. A variety of substituted aryl acetylenes underwent smooth dimerization using catalytic FeCl(3) and DMEDA in the presence of KO(t)Bu. 相似文献
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Nishiura M Hou Z Wakatsuki Y Yamaki T Miyamoto T 《Journal of the American Chemical Society》2003,125(5):1184-1185
Various terminal alkynes have been cleanly dimerized into the corresponding head-to-head (Z)-enynes by use of the half-metallocene lutetium alkyl complexes Me2Si(C5Me4)(NAr)Lu(CH2SiMe3)(THF) (Ar = Ph, C6H3Me2-2,6, C6H2Me3-2,4,6) as catalysts. Aromatic C-Cl, C-Br, and C-I bonds, which are known to be extremely susceptible to reductive cleavage by transition metals, survived in the present reactions. The corresponding dimeric alkynide species [Me2Si(C5Me4)(NAr)Lu(mu-CCR)]2 are thought to be the true catalysts, some of which have been isolated and structurally characterized. These alkynide species were thermally stable and soluble at the reaction temperatures (80-110 degrees C), but they precipitated upon cooling to room temperature after completion of the reaction. Therefore, this catalyst system works homogeneously but can be separated and reused, thus constituting the first example of a recyclable catalyst system for the dimerization of terminal alkynes and also the first example of (Z)-selective head-to-head dimerization of aromatic terminal alkynes. 相似文献
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The oxidative cross-coupling of terminal alkynes with arylboronic acids catalyzed by the porous palladium nanospheres was developed. In the presence of silver oxide, triphenylphosphine and cesium carbonate, the reaction provided the corresponding arylalkynes with good to excellent yields. There were also other obvious advantages such as broad applicability, high selectivity, simple experimental operation as well as the convenient preparation, high efficiency and reusability of catalyst. The possible mechanism of this transition-metal nanoparticles catalyzed oxidative cross-coupling reaction of two nucleophiles was proposed. 相似文献