- Efficient functionalization of olefins by arylsilanes catalyzed by palladium anionic complexes
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The coupling of organosilanes and different olefins was performed efficiently in the presence of anionic complexes, [CA]2[PdX4] and [CA]2[Pd2X6], where CA?=?imidazolium or pyridinium cation. The reaction proceeds according to a Pd(II)-mediated pathway, and Cu(OAc)2 acts as the re-oxidant of Pd(0) formed during the catalytic process. High product yields were obtained for differently substituted olefins at 80?°C in 4?h. Styrylsilanes reacted in the same conditions giving unsymmetrical 1,3-dienes.
- Silarska,Majchrzak,Marciniec,Trzeciak
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p. 458 - 464
(2016/12/16)
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- CaII-Catalyzed Alkenylation of Alcohols with Vinylboronic Acids
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Direct alkenylation of a variety of alcohols with vinylboronic acids has been accomplished using the air-stable calcium(II) complex Ca(NTf2)2 under mild conditions with short reaction times. For reluctant transformations, an ammonium salt was used as an additive to circumvent the reactivity issue. Cross-coupling: Direct alkenylation of a variety of alcohols with vinylboronic acids has been accomplished using the air-stable calcium(II) complex Ca(NTf2)2 under mild conditions with short reaction times (see scheme)
- Leb?uf, David,Presset, Marc,Michelet, Bastien,Bour, Christophe,Bezzenine-Lafollée, Sophie,Gandon, Vincent
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supporting information
p. 11001 - 11005
(2015/11/10)
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- Alkyl transfer from C-C cleavage: Replacing the nitro group of nitro-olefins
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Alkyl substituted Hantzsch esters are rationally used as alkylation reagents to replace the nitro groups of nitro olefins to give excellent yields of trans-olefins. The reaction mechanism is considered to proceed through a free radical mechanism, which is different from the corresponding transfer alkylation of imines. This journal is the Partner Organisations 2014.
- Li, Guangxun,Wu, Lei,Lv, Gang,Liu, Hongxin,Fu, Qingquan,Zhang, Xiaomei,Tang, Zhuo
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supporting information
p. 6246 - 6248
(2014/06/09)
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- Copper-catalyzed oxidative heck reactions between alkyltrifluoroborates and vinyl arenes
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We report herein that potassium alkyltrifluoroborates can be utilized in oxidative Heck-type reactions with vinyl arenes. The reaction is catalyzed by a Cu(OTf)2/1,10-phenanthroline with MnO2 as the stoichiometric oxidant. In addition to the alkyl Heck, amination, esterification, and dimerization reactions of alkyltrifluoroborates are demonstrated under analogous reaction conditions. Evidence for an alkyl radical intermediate is presented.
- Liwosz, Timothy W.,Chemler, Sherry R.
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supporting information
p. 3034 - 3037
(2013/07/26)
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- Facile coupling of propargylic, allylic and benzylic alcohols with allylsilane and alkynylsilane, and their deoxygenation with Et3SiH, catalyzed by Bi(OTf)3 in [BMIM][BF4] ionic liquid (IL), with recycling and reuse of the IL
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Allyltrimethylsilane (allyl-TMS) reacts with propargylic alcohols 1a-1d in the presence of 10% Bi(OTf)3 in [BMIM][BF4] solvent to furnish the corresponding 1,5-enynes in respectable isolated yields (87-93%) at room temperature. The utility of Bi(OTf)3 as a superior catalyst was demonstrated in a survey study on coupling of allyl-TMS with 1a employing several metallic triflates (Bi, Ln, Al, Yb) as well as, B(C6F 5)3, Zn(NTf2)2 and Bi(NO 3)3·5H2O. Coupling of cyclopropyl substituted propargylic alcohol 1e with allyl-TMS gave the skeletally intact 1,5-enyne and a ring opened derivative as a mixture. Coupling of propargylic/allylic alcohol 1f with allyl-TMS resulted in allylation at both benzylic (2 isomers) and propargylic positions, as major and minor products respectively. The scope of this methodology for allylation of a series of allylic and benzylic alcohols was explored. Chemoselective reduction of a host of propargylic, propagylic/allylic, bis-allylic, allylic, and benzylic alcohols with Et3SiH was achieved in high yields with short reaction times. The same approach was successfully applied to couple representative propargylic and allylic alcohols with 1-phenyl-2-trimethylsilylacetylene. The recovery and reuse of the ionic liquid (IL) was gauged in a case study with minimal decrease in isolated yields after six cycles.
- Narayana Kumar,Laali, Kenneth K.
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experimental part
p. 7347 - 7355
(2012/09/25)
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- Rapid selective defunctionalization of the carbonyl group of α,β-unsaturated ketones with trialkoxylsilane/ZnX2
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Reduction of the carbonyl group of ketones to a methylene unit is widely applied in organic syntheses. In this article, we report that trialkoxylsilane/Zn-based catalyst systems may be applied in the reduction of the carbonyl groups of α,β-unsaturated ketones to methylene units under very mild conditions. In comparison with other Zn-based catalysts, excellent rates and high conversions of,-unsaturated ketones to methylene units are obtained using trialkoxylsilane/ZnI2 or ZnCl2. And the same time, the hydrosilylation reaction product could only be detected when using CuI, CuCl, or FeCl3. No reaction could be conducted by using trialkoxylsilane/CoCl2 or NiCl2, in comparison with Zn-based catalysts. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. Copyright Taylor &Francis Group, LLC.
- Li, Jiayun,Peng, Jiajian,Bai, Ying,Chen, Lingzhen,Lai, Guoqiao
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scheme or table
p. 1621 - 1625
(2011/10/04)
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- Decarboxylative C-C bond cleavage reactions via oxapalladacycles
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In the presence of Pd(0) catalyst and triethylborane, 3-hydroxy-4-pentenoic acids undergo C-C bond cleavage reactions via oxapalladacyclopentanones to provide conjugated dienes with evolution of carbon dioxide. The Japan Institute of Heterocyclic Chemistry.
- Kimura, Masanari,Kohno, Tomohiko,Toyoda, Kei,Mori, Takamichi
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experimental part
p. 281 - 287
(2011/04/16)
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- Palladium-tetraphosphine complex catalysed heck reaction of vinyl bromides with alkenes: A powerful access to conjugated dienes
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A wide variety of 1,3-dienes have been prepared by the Heck vinylation of vinyl bromides using [Pd(η3-C3H5)Cl] 2/cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphino)methyl] cyclopentane (Tedicyp) as the catalyst precursor. Both α- and β-substituted vinyl bromides undergo the Heck reaction with functionalised alkenes such as acrylates, enones, styrenes or a vinyl sulfone, and also with nonfunctionalised alkenes such as dec-1-ene, leading stereoselectively, in most cases, to the corresponding E- or E,E-1,3-dienes in good yields. Furthermore, this catalyst can be used at low loading for several reactions. Georg Thieme Verlag Stuttgart.
- Lemhadri, Mhamed,Battace, Ahmed,Berthiol, Florian,Zair, Touriya,Doucet, Henri,Santelli, Maurice
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p. 1142 - 1152
(2008/12/22)
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- Heck reaction of vinyl bromides with alkenes in the presence of a tetraphosphine/palladium catalyst
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Through the use of [PdCl(C3H5)]2- cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of vinyl bromides undergo Heck reaction with a wide variety of alkenes leading selectively to the corresponding 1,3-dienes in good yields. Furthermore, it can be used at low loading even for reactions of sterically hindered vinyl bromides.
- Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 841 - 844
(2007/10/03)
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- Equilibrium acidities of some α,ω-diphenylpolyenes
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Cesium ion pair acidities were measured in THF for a series of diphenylmethane vinylogues that form α,ω-diphenylpolyenyl anions with linearly conjugated chains of 3-9 carbon atoms. The dissociation constants of the diphenylpolyenyls in THF were determined by UV-vis spectroscopy and are rationalized with an electrostatic model. Acidity and dissociation data were combined with measurements of stereoisomer equilibria to estimate the differences in delocalization energy among the diphenylpolyenyl ions. The experimental differences in acidity correlate well with AMI and molecular mechanics (MMPI) calculations.
- Thiele, Georg,Streitwieser, Andrew
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p. 446 - 454
(2007/10/02)
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- How far can a carbanion delocalize? 13C NMR studies on soliton model compounds
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For well-defined π systems, 13C chemical shifts are correlated with π-electron density. We have used this correlation to develop models for charge carriers in n-doped polyacetylene ("solitons") that allow us to determine if the charge density d
- Tolbert, Laren M.,Ogle, Mark E.
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p. 9519 - 9527
(2007/10/02)
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- Polylithium Complexes from Phenyl-substituted 1,6,6aλ4-Trithiapentalenes and Related Compounds and Lithium
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Phenyl-substituted 1,6,6aλ4-trithiapentalenes (1a-d) and 3H-1,2-dithiole-3-thiones (2a,b), 2-(4-phenyl-3H-1,2-dithiol-3-ylidene)acetophenone (3), and 1,5-diphenyl-1,3,5-pentanetrione (4) react in tetrahydrofuran or 2-methyltetrahydrofuran at 0 deg C with 7-10 Li/mol to form highly reactive, soluble polylithium complexes.These can be precipitated from solution by addition of pentane and have the composition A Li7-10*THF, where A = starting compound.The polylithium complex obtained from 1a and 10 Li is suggested to have the constitution 5a on the basis of reaction with water, methyl iodide, pentacene, and hydrogen, respectively.The assumption that 5a and the analogous complex 5b (formed by reacting 1b and 9 Li) contain Li2S molecules in complexed form is supported in particular by solid state 7Li and 1H NMR measurements.
- Bogdanovic, Borislav,Cordi, Alexis,Stepowska, Halszka,Locatelli, Paolo,Wermeckes, Bernd,et.al.
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