共查询到20条相似文献,搜索用时 15 毫秒
1.
Komeyama K Sasayama D Kawabata T Takehira K Takaki K 《The Journal of organic chemistry》2005,70(26):10679-10687
[reaction: see text] Rare-earth silylamides, Ln[N(SiMe3)2]3 (Ln = Y, La, Sm, Yb), serve as good catalysts for monoinsertion of isocyanides into terminal alkynes in the presence of amine additives, leading to 1-aza-1,3-enyens in excellent yields. The reaction is applicable to a diverse set of terminal alkynes with various functionalities such as ethers, acetals, and amino groups. Larger metals (La and Sm) give a better performance than smaller ones (Y and Yb). Using less hindered primary amines and, in contrast, bulky isocyanides is crucial for the coupling reaction; otherwise, competitive oligomerization of the isocyanides occurs predominantly. In the mechanistic study, the rate-determining step of the reaction seems to be the first insertion of the isocyanides into rare-earth alkynides, which is followed by spontaneous protonation with the amine additives. 相似文献
2.
Jahier C Zatolochnaya OV Zvyagintsev NV Ananikov VP Gevorgyan V 《Organic letters》2012,14(11):2846-2849
A general highly regio- and stereoselective palladium-catalyzed head-to-head dimerization reaction of terminal acetylenes is presented. This methodology allows for the efficient synthesis of a variety of 1,4-enynes as single E stereoisomers. Computational studies reveal that this dimerization reaction proceeds via the hydropalladation pathway. 相似文献
3.
4.
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
5.
Shoko Nagata Michiko Matsumoto Akihiro Nomoto Akiya Ogawa 《Tetrahedron letters》2007,48(38):6637-6640
A novel palladium-catalyzed hydrophosphination of alkynes with tetraphenyldiphosphine takes place regioselectively to provide vinylic phosphines, which undergo air-oxidation during workups, affording the corresponding vinylphosphine oxides in good yields. 相似文献
6.
Liang Chen 《Tetrahedron letters》2004,45(13):2771-2774
The combination of palladium and copper catalyzes the addition of terminal alkynes to electron-deficient alkynes selectively and effectively in water without the competition of terminal alkynes’ homo-coupling. 相似文献
7.
A one‐pot synthesis of alkynyl sulfide from terminal alkyne has been reported via lithiation of the alkyne, oxidative addition of sulfur, consecutively followed by the nucleophilic substitution of lithium alkynyl thiolate to various halides. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:105–110, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20745 相似文献
8.
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
9.
A regioselective and stereoselective palladium-catalyzed dimerization of terminal alkynes method for the synthesis of symmetrical (Z,Z)-1,4-dihalo-1,3-dienes is presented. In the presence of a catalytic amount of PdX(2) and 3 equiv of CuX(2) (X = Cl and Br), terminal alkynes were dimerized to afford (Z,Z)-1,4-dihalo-1,3-dienes in good yields. The results showed that the effect of solvent had a fundamental influence on the chemoselectivity of the dimerization reaction. The mechanism of the palladium-catalyzed dimerization reaction is also discussed. 相似文献
10.
ter Maat J Regeling R Ingham CJ Weijers CA Giesbers M de Vos WM Zuilhof H 《Langmuir : the ACS journal of surfaces and colloids》2011,27(22):13606-13617
Porous anodic alumina (PAA) is a well-defined material that has found many applications. The range of applications toward sensing and recognition can be greatly expanded if the alumina surface is covalently modified with an organic monolayer. Here, we present a new method for the organic modification of PAA based on the reaction of terminal alkynes with the alumina surface. The reaction results in the the formation of a monolayer within several hours at 80 °C and is dependent on both oxygen and light. Characterization with X-ray photoelectron spectroscopy and infrared spectroscopy indicates formation of a well-defined monolayer in which the adsorbed species is an oxidation product of the 1-alkyne, namely, its α-hydroxy carboxylate. The obtained monolayers are fairly stable in water and at elevated temperatures, as was shown by monitoring the water contact angle. Modification with 1,15-hexadecadiyne resulted in a surface that has alkyne end groups available for further reaction, as was demonstrated by the subsequent reaction of N-(11-azido-3,6,9-trioxaundecyl)trifluoroacetamide with the modified surface. Biofunctionalization was explored by coupling 11-azidoundecyl lactoside to the surface and studying the subsequent adsorption of the lectin peanut agglutinin (PNA) and the yeast Candida albicans, respectively. Selective and reversible binding of PNA to the lactosylated surfaces was demonstrated. Moreover, PNA adsorption was higher on surfaces that exposed the β-lactoside than on those that displayed the α anomer, which was attributed to surface-associated steric hindrance. Likewise, the lactosylated surfaces showed increased colonization of C. albicans compared to unmodified surfaces, presumably due to interactions involving the cell wall β-glucan. Thus, this study provides a new modification method for PAA surfaces and shows that it can be used to induce selective adsorption of proteins and microorganisms. 相似文献
11.
Dinuclear and mononuclear palladium complexes having N,N'-bis[2-(diphenylphosphino)phenyl]amidinate (DPFAM) as a ligand catalyzed the cross-addition of triisopropylsilylacetylene (TIPSA) to unactivated internal alkynes, giving enynes selectively. When palladium catalysts having PPh3, TDMPP, dppe, or dppf were used, dimers of TIPSA were obtained as major products. The reactions of TIPSA with several terminal alkynes also gave cross-adducts selectively, although the yields were moderate. 相似文献
12.
<正>A highly efficient and regio-/stereoselective method of hydrosilylating terminal alkynes was developed using Pt(DVDS)-tri(t-butyl) phosphine catalyst system at room temperature.Trans-products or alpha-products were obtained almost exclusively depending on the alkynes and silanes employed. 相似文献
13.
Guoqiang Wang Xiaoshi Su Liuzhou Gao Xueting Liu Guoao Li Shuhua Li 《Chemical science》2021,12(32):10883
Here, we describe simple B(C6F5)3-catalyzed mono- and dihydrosilylation reactions of terminal alkynes by using a silane-tuned chemoselectivity strategy, affording vinylsilanes and unsymmetrical geminal bis(silanes). This strategy is applicable to the dihydrosilylation of both aliphatic and aryl terminal alkynes with different silane combinations. Gram-scale synthesis and conducting the reaction without the exclusion of air and moisture demonstrate the practicality of this methodology. The synthetic utility of the resulting products was further highlighted by the structural diversification of geminal bis(silanes) through transforming the secondary silane into other silyl groups. Comprehensive theoretical calculations combined with kinetical isotope labeling studies have shown that a prominent kinetic differentiation between the hydrosilylation of alkynes and vinylsilane is responsible for the chemoselective construction of unsymmetrical 1,1-bis(silanes).A B(C6F5)3/silane-based system enables the chemoselective dihydrosilylation of terminal alkynes. Using a combination of different types of hydrosilanes, a series of unsymmetrical or symmetrical 1,1-bis(silanes) could be constructed. 相似文献
14.
In(OTf)(3) is reported as the first catalyst having the ability to selectively catalyse both Markovnikov and anti-Markovnikov hydrothiolation of terminal alkynes under identical reaction conditions depending upon the nature of the thiol employed. 相似文献
15.
de Graaf AJ Mastrobattista E van Nostrum CF Rijkers DT Hennink WE Vermonden T 《Chemical communications (Cambridge, England)》2011,47(24):6972-6974
This communication describes a novel and fast reaction to substitute the living chain end after Atom Transfer Radical Polymerization (ATRP) by an azide functionality. The reaction is catalyzed by the ATRP catalyst at room temperature in aqueous solution and can be followed by a 'click' reaction using again the same catalyst. 相似文献
16.
Join B Mimeau D Delacroix O Gaumont AC 《Chemical communications (Cambridge, England)》2006,(30):3249-3251
Preliminary results dealing with the synthesis of non-racemic P-stereogenic vinylphosphine-boranes by hydrophosphination of alkynes in the presence of a chiral catalyst are reported. 相似文献
17.
A Palladium/imidazolium chloride system has been used to mediate the dimerization of terminal alkynes to enynes. The combination of 1 mol % Pd(OAc)(2) and 2 mol % IMes.HCl in the presence of Cs(2)CO(3) as base shows high activity and high regio- and steroselectivity for the dimerization of aryl and aliphatic terminal alkynes to enynes. 相似文献
18.
Kawaguchi S Nagata S Nomoto A Sonoda M Ogawa A 《The Journal of organic chemistry》2008,73(20):7928-7933
A novel transition-metal-catalyzed hydrophosphination of terminal alkynes using a diphosphine-hydrosilane binary system takes place regioselectively to provide vinylic phosphines, which undergo air oxidation during workup, affording the corresponding vinylphosphine oxides in good yields. In this hydrophosphination, hydrosilanes act as a useful hydrogen source, and furthermore, small amounts of oxygen is required to accomplish the reaction efficiently. 相似文献
19.
The complexes [(η6-arene)Ru=C(OMe)CH2R′)Cl(PR3)]PF6 (R′ = Ph; ARENE = Me4C6H2, iPr3C6H3, Et3C6H3; PR3 = PMe3, PPh3, P(OMe)3) have been made from RuCl2(PR3)(arene) precursors by activation at room temperature of phenylacetylene in methanol containing NaPF6. The complex with R′ = nBu, ARENE = Me4C6H2, and PR3 = PMe3 is similarly formed from hex-1-yne but much more slowly, and a complex of the type [(p-cymene)Ru=C(OMe)CH2R′)Cl(PR3)]+PF6− could be obtained only when the phosphine was the bulky PPh3 (10b). It has been shown that the steric hindrance by both arene and phosphine ligands contributes to the stabilization of the carbeneruthenium complexes. 相似文献