- Pd-Catalyzed reductive heck reaction of olefins with aryl bromides for Csp2-Csp3 bond formation
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We developed a Pd-catalyzed intermolecular reductive Heck reaction to construct Csp2-Csp3 bonds between aryl bromides and olefins. Various styrene derivatives, acyclic and cyclic alkenes, were well tolerated to couple with varied aryl bromides in linear selectivity. Kinetic and deuterium labeling experiments suggested that i-PrOH provides a hydride through β-H elimination.
- Jin, Liqun,Qian, Jiaxia,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan
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supporting information
p. 5752 - 5755
(2018/06/07)
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- Nickel-catalyzed coupling reaction of alkyl halides with aryl Grignard reagents in the presence of 1,3-butadiene: Mechanistic studies of four-component coupling and competing cross-coupling reactions
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We describe the mechanism, substituent effects, and origins of the selectivity of the nickel-catalyzed four-component coupling reactions of alkyl fluorides, aryl Grignard reagents, and two molecules of 1,3-butadiene that affords a 1,6-octadiene carbon framework bearing alkyl and aryl groups at the 3- and 8-positions, respectively, and the competing cross-coupling reaction. Both the four-component coupling reaction and the cross-coupling reaction are triggered by the formation of anionic nickel complexes, which are generated by the oxidative dimerization of two molecules of 1,3-butadiene on Ni(0) and the subsequent complexation with the aryl Grignard reagents. The C-C bond formation of the alkyl fluorides with the γ-carbon of the anionic nickel complexes leads to the four-component coupling product, whereas the cross-coupling product is yielded via nucleophilic attack of the Ni center toward the alkyl fluorides. These steps are found to be the rate-determining and selectivity-determining steps of the whole catalytic cycle, in which the C-F bond of the alkyl fluorides is activated by the Mg cation rather than a Li or Zn cation. ortho-Substituents of the aryl Grignard reagents suppressed the cross-coupling reaction leading to the selective formation of the four-component products. Such steric effects of the ortho-substituents were clearly demonstrated by crystal structure characterizations of ate complexes and DFT calculations. The electronic effects of the para-substituent of the aryl Grignard reagents on both the selectivity and reaction rates are thoroughly discussed. The present mechanistic study offers new insight into anionic complexes, which are proposed as the key intermediates in catalytic transformations even though detailed mechanisms are not established in many cases, and demonstrates their synthetic utility as promising intermediates for C-C bond forming reactions, providing useful information for developing efficient and straightforward multicomponent reactions.
- Iwasaki, Takanori,Fukuoka, Asuka,Yokoyama, Wataru,Min, Xin,Hisaki, Ichiro,Yang, Tao,Ehara, Masahiro,Kuniyasu, Hitoshi,Kambe, Nobuaki
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p. 2195 - 2211
(2018/03/05)
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- Development of a Palladium-Catalyzed Process for the Synthesis of Z-Alkenes by Sequential Sonogashira–Hydrogenation Reaction
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A novel and selective sequential one-pot protocol for the synthesis of Z-alkenes via Sonogashira–semihydrogenation is reported. The efficiency of the methodology is increased by utilizing PdCl2/BuPAd2 as homogeneous catalyst for the Sonogashira coupling and subsequently transforming the transition metal complex into a heterogeneous Pd hydrogenation catalyst. This methodology represents one of the rare examples directly combining homogeneous and heterogeneous catalysis.
- Hancker, S?ren,Neumann, Helfried,Beller, Matthias
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p. 5253 - 5259
(2018/09/14)
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- Carbon-carbon bond formation reactivity of a four-coordinate NHC-supported iron(II) phenyl compound
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The preparation and characterization of a NHC-coordinated (NHC = N-heterocyclic carbene) ferrous phenyl complex [(IPr2Me2)2FePh2] (1; IPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) as well as its C-C bond formation reactivity have been studied. The four-coordinate iron(II) phenyl complex was prepared from the reaction of ferrous chloride with PhMgBr and IPr2Me2. It reacts with nonactivated primary and secondary alkyl bromides and chlorides to furnish cross-coupling products and the iron(II) monophenyl species (IPr2Me2)2FePhX (X = Br (2), Cl). When it is treated with cyclooctatetraene (cot) or [Cp2Fe][BArF4] in the presence of PMe3, it undergoes coordination or one-electron oxidation induced reductive elimination of biphenyl to form the corresponding iron(0) or iron(I) species [(IPr2Me2)2Fe(?·4-cot)] (3) or [(IPr2Me2)2Fe(PMe3)2][BArF4] (4). All of these iron-containing products have been fully characterized by various spectroscopic methods. Complex 1 and (IPr2Me2)2FeCl2 catalyze the reaction of n-C8H17Br with (p-tolyl)MgBr to afford the cross-coupling product in moderate yields (49% and 47%), whereas the reactions employing 4 and 1/PMe3 as catalysts give the cross-coupling product in very low yields. The results reflect the complexity of the reaction mechanism of iron-catalyzed coupling reactions.
- Liu, Yuesheng,Xiao, Jie,Wang, Lei,Song, You,Deng, Liang
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p. 599 - 605
(2015/03/05)
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- Synthesis of mixed silylene-carbene chelate ligands from nheterocyclic silylcarbenes mediated by nickel
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The NiII -mediated tautomerization of the N-heterocyclic hydrosilylcarbene L2Si(H)(CH2)NHC1, where L2 = CH(C=CH2)(CMe)(NAr)2, Ar = 2,6-iPr2C6H3 ; NHC = 3,4,5-trimethylimidazol-2-yliden-6-yl, leads to the first N-heterocyclic silylene (NHSi)-carbene (NHC) chelate ligand in the dibromo nickel(II) complex [L1SiD(CH2)(NHC)NiBr2]2 (L1 = CH(MeC=NAr)2). Reduction of 2 with KC8 in the presence of PMe3 as an auxiliary ligand afforded, depending on the reaction time, the N-heterocyclic silyl-NHC bromo NiII complex [L2Si(CH2)NHCNiBr(PMe3)] 3 and the unique Ni0 complex [h2(Si-H){L2Si(H)(CH2)NHC}Ni(PMe3)2] ,inf>4 featuring an agostic Si-H→!Ni bonding interaction. When 1,2-bis(dimethylphosphino)ethane (DMPE) was employed as an exogenous ligand, the first NHSi-NHC chelate-ligand-stabilized Ni0 complex [L1SiD(CH2)NHCNi(dmpe)] 5 could be isolated. Moreover, the dicarbonyl Ni0 complex 6, [L1SiD-(CH2)NHCNi(CO)2], is easily accessible by the reduction of 2 with K(BHEt3) under a CO atmosphere. The complexes were spectroscopically and structurally characterized. Furthermore, complex 2 can serve as an efficient precatalyst for Kumada-Corriu-type cross-coupling reactions.
- Tan, Gengwen,Enthaler, Stephan,Inoue, Shigeyoshi,Blom, Burgert,Driess, Matthias
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supporting information
p. 2214 - 2218
(2015/02/19)
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- Iron phosphine catalyzed cross-coupling of tetraorganoborates and related group 13 nucleophiles with alkyl halides
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Iron phosphine complexes prove to be good precatalysts for the cross-coupling of alkyl, benzyl, and allyl halides with not only aryl triorganoborate salts but also related aluminum-, gallium-, indium-, and thallium-based nucleophiles. Mechanistic studies revealed that while Fe(I) can be accessed on catalytically relevant time scales, lower average oxidation states are not formed fast enough to be relevant to catalysis. EPR spectroscopic studies reveal the presence of bis(diphosphine)iron(I) complexes in representative catalytic reactions and related processes with a range of group 13 nucleophiles. Isolated examples were studied by M?ssbauer spectroscopy and single-crystal X-ray structural analysis, while the electronic structure was probed by dispersion-corrected B3LYP DFT calculations. An EPR study on an iron system with a bulky diphosphine ligand revealed the presence of an S = 1/2 species consistent with the formation of a mono(diphosphine)iron(I) species with inequivalent phosphine donor environments. DFT analysis of model complexes allowed us to rule out a T-shaped Fe(I) structure, as this is predicted to be high spin.
- Bedford, Robin B.,Brenner, Peter B.,Carter, Emma,Clifton, Jamie,Cogswell, Paul M.,Gower, Nicholas J.,Haddow, Mairi F.,Harvey, Jeremy N.,Kehl, Jeffrey A.,Murphy, Damien M.,Neeve, Emily C.,Neidig, Michael L.,Nunn, Joshua,Snyder, Benjamin E. R.,Taylor, Joseph
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p. 5767 - 5780
(2015/02/19)
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- Efficient cross-coupling of aryl Grignard reagents with alkyl halides by recyclable ionic iron(iii) complexes bearing a bis(phenol)-functionalized benzimidazolium cation
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A novel bis(phenol)-functionalized benzimidazolium salt, 1,3-bis(3,5-di-tert-butyl-2-hydroxybenzyl)benzimidazolium chloride (H 3LCl, 1), was designed and used to prepare ionic iron(iii) complexes of the type [H3L][FeX4] (X = Cl, 2; X = Br, 3). Both 2 and 3 were characterized by elemental analysis, Raman spectroscopy, electrospray ionization mass spectrometry and X-ray crystallography. The catalytic performances of 2 and 3 in cross-coupling reactions using aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens were studied. This analysis shows that complex 2 has good potential for alkyl chloride-mediated coupling. In comparison, complex 3 showed slightly lower catalytic activity. After decanting the product contained in the ethereal layer, complex 2 could be recycled at least eight times without significant loss of catalytic activity.
- Xia, Chong-Liang,Xie, Cun-Fei,Wu, Yu-Feng,Sun, Hong-Mei,Shen, Qi,Zhang, Yong
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p. 8135 - 8144
(2013/12/04)
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- Cross-coupling of alkyl halides with aryl or alkyl Grignards catalyzed by dinuclear Ni(ii) complexes containing functionalized tripodal amine-pyrazolyl ligands
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Structurally distinctive dinuclear Ni(ii) complexes with furan or thiophene tethered amine-pyrazolyl tripodal hybrid ligands have been synthesized and crystallographically characterized. All complexes are catalytically active towards cross-coupling of aryl/alkyl Grignard reagents with β-H containing alkyl halides at room temperature in the presence of N,N,N',N'- tetramethylethylenediamine (TMEDA). The catalytic efficacy of the complexes is dependent on the tether substituent at the central amine. Two species, Ni(ii) TMEDA and Mg(ii) TMEDA complexes, have been isolated from the catalytic reaction mixtures under different conditions. Some ligand-stabilized Ni(ii) and Mg(ii) bimetallic species have also been identified in the ESI-MS spectra.
- Xue, Fei,Zhao, Jin,Hor, T. S. Andy
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p. 5150 - 5158
(2013/04/10)
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- Dinuclear iron complex-catalyzed cross-coupling of primary alkyl fluorides with aryl grignard reagents
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Iron-catalyzed cross-coupling of nonactivated primary alkyl fluorides with aryl Grignard reagents has been achieved by using the low-coordinate dinuclear iron complex [(IPr2Me2)Fe(μ2-NDipp) 2Fe(IPr2Me2)] as the catalyst. This iron-catalyzed C(sp3)-F bond arylation reaction is applicable to a variety of aryl Grignard reagents and primary alkyl fluorides. The product pattern suggests the involvement of a radical-type mechanism for its C-F bond scission step.
- Mo, Zhenbo,Zhang, Qiang,Deng, Liang
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p. 6518 - 6521
(2012/10/29)
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- Ionic iron(iii) complexes of bis(phenol)-functionalized imidazolium cations: Synthesis, structures and catalysis for aryl Grignard cross-coupling of alkyl halides
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A series of bis(phenol)-functionalized imidazolium salts, 1,3-bis(4,6-di-R1-2-hydroxybenzyl)-2-R2-4,5-di-R 3-imidazolium chlorides H3LnCl (R1 = tBu, R2 = R3 = H, H3L 1Cl, 1; R1 = CH3, R2 = R3 = H, H3L2Cl, 2; R1 = tBu, R 2 = H, R3 = Cl, H3L3Cl, 3; R 1 = tBu, R2 = CH3, R3 = H, H3L4Cl, 4), were used to produce a novel series of ionic iron(iii) complexes [H3Ln][FeX4] (n = 1, X = Cl, 5; n = 2, X = Cl, 6; n = 3, X = Cl, 7; n = 4, X = Cl, 8; n = 1, X = Br, 9; n = 3, X = Br, 10). All of the complexes were characterized by Raman spectroscopy and electrospray ionization mass spectrometry. Elemental analysis and X-ray crystallography were also used. All of the complexes were non-hygroscopic and air-stable, with five of them existing as solids (5, 7-10) and one as an oil (6) at room temperature. A preliminary catalytic study on the cross-coupling reactions of aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens, revealed that all of the ionic iron(iii) complexes exhibited good to excellent catalytic activity. Complexes 5, 6 and 8 exhibited optimal activity, whereas 7, 9 and 10 showed only moderate activity. Furthermore, by simply decanting the cross-coupling product in the ether layer, complexes 5 and 6 could be reused in at least seven successive runs without significant loss in catalytic activity.
- Deng, Hai-Ning,Xing, Ya-Lin,Xia, Cong-Liang,Sun, Hong-Mei,Shen, Qi,Zhang, Yong
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p. 11597 - 11607
(2013/02/23)
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- Selective catalytic C-H alkylation of alkenes with alcohols
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Alkenes and alcohols are among the most abundant and commonly used organic feedstock in industrial processes. We report a selective catalytic alkylation reaction of alkenes with alcohols that forms a carbon-carbon bond between vinyl carbon-hydrogen (C-H) and carbon-hydroxy centers with the concomitant loss of water. The cationic ruthenium complex [(C6H6)(PCy 3)(CO)RuH]+BF4- (Cy, cyclohexyl) catalyzes the alkylation in solution within 2 to 8 hours at temperatures ranging from 75° to 110°C and tolerates a broad range of substrate functionality, including amines and carbonyls. Preliminary mechanistic studies are inconsistent with Friedel-Crafts-type electrophilic activation of the alcohols, suggesting instead a vinyl C-H activation pathway with opposite electronic polarization.
- Lee, Dong-Hwan,Kwon, Ki-Hyeok,Yi, Chae S.
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scheme or table
p. 1613 - 1616
(2012/02/01)
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- Iron(II) complexes with functionalized amine-pyrazolyl tripodal ligands in the cross-coupling of aryl Grignard with alkyl halides
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Structurally distinctive Fe(ii) complexes with furan, thiophene and pyridine functionalized amine-pyrazolyl tripodal hybrid ligands have been synthesized and crystallographically characterized. The tether substituent at the central amine plays an active role in determining the coordination mode of the ligand and the metal geometry. All complexes are catalytically active towards cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides with β-hydrogen under ambient conditions. ESI-MS spectra analysis revealed the ligand-stabilised Fe(ii) and Mg(ii) species. The Royal Society of Chemistry 2011.
- Xue, Fei,Zhao, Jin,Hor, T. S. Andy
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experimental part
p. 8935 - 8940
(2011/10/19)
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- Synthesis of anionic iron(II) complex bearing an n-heterocyclic carbene ligand and its catalysis for aryl grignard cross-coupling of alkyl halides
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The reaction of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) with one equivalent of a novel imidazolium salt of iron(II), [FeBr 3(C4H8O)](HIPr)·C4H 8O (1), afforded the anionic iron(II) comp
- Gao, Huan-Huan,Yan, Chun-Hui,Tao, Xue-Ping,Xia, Ying,Sun, Hong-Mei,Shen, Qi,Zhang, Yong
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experimental part
p. 4189 - 4192
(2011/01/03)
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- Functional group tolerant Kumada-Corriu-Tamao coupling of nonactivated alkyl halides with aryl and heteroaryl nucleophiles: Catalysis by a nickel pincer complex permits the coupling of functionalized Grignard reagents
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A nickel(II) pincer complex [(MeNN2)NiCl] (1) catalyzes Kumada-Corriu-Tamao cross coupling of nonactivated alkyl halides with aryl and heteroaryl Grignard reagents. The coupling of octyl bromide with phenylmagnesium chloride was used as a test reaction. Using 3 mol % of 1 as the precatalyst and THF as the solvent, and in the presence of a catalytic amount of TMEDA, the coupling product was obtained in a high yield. The reaction conditions could be applied to cross coupling of other primary and secondary alkyl bromides and iodides. The coupling is tolerant to a wide range of functional groups. Therefore, alkyl halides containing ester, amide, ether, thioether, alcohol, pyrrole, indole, furan, nitrile, conjugated enone, and aryl halide moieties were coupled to give high isolated yields of products in which these units stay intact. For the coupling of ester-containing substrates, O-TMEDA is a better additive than TMEDA. The reaction protocol proves to be efficient for the coupling of Knochel-type functionalized Grignard reagents. Thus aryl Grignard reagents containing electron-deficient and/or sensitive ester, nitrile, amide, and CF3 substituents could be successfully coupled to nonactivated and functionalized alkyl iodides. The catalysis is also efficient for the coupling of alkyl iodides with functionalized heteroaryl Grignard reagents, giving rise to pyridine-, thiophene-, pyrazole-, furan-containing molecules with additional functionalities. Concerning the mechanism of the catalysis, [(MeNN2)Ni-(hetero)Ar] was identified as an intermediate, and the activation of alkyl halides was found to take place through a radical-rebound process.
- Vechorkin, Oleg,Proust, Valerie,Hu, Xile
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supporting information; experimental part
p. 9756 - 9766
(2011/03/19)
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- Cobalt-catalyzed cross-coupling reactions of aryl bromides with alkyl grignard reagents
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Aryl bromides react with primary alkyl Grignard reagents in the presence of N,N,N′,N′-tetramethyl-1,3-propanediamine and catalytic amounts of cobalt(II) chloride and an N-heterocyclic carbene to yield the corresponding cross-coupling products in high yields. Copyright
- Hamaguchi, Hiroyuki,Uemura, Minoru,Yasui, Hiroto,Yorimitsu, Hideki,Oshima, Koichiro
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experimental part
p. 1178 - 1179
(2011/02/28)
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- Iron-catalyzed desulfinylative C-C cross-coupling reactions of sulfonyl chlorides with grignard reagents
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(Chemical Equation Presented) A friendly couple: Conditions have been uncovered that allow the desulfinylative C-C cross-coupling reaction of inexpensive sulfonyl chlorides and Grignard reagents (see scheme, acac = acetylacetonate, NMP = N-methylpyrrolidone). The reactions rely on environmentally friendly iron catalysts and do not require expensive and/or toxic ligands.
- Rao Volla, Chandra M.,Vogel, Pierre
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p. 1305 - 1307
(2008/12/22)
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- Iron(III) amine-bis(phenolate) complexes as catalysts for the coupling of alkyl halides with aryl Grignard reagents
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Catalytic cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens is achieved using Fe(III) amine-bis(phenolate) halide complexes. The Royal Society of Chemistry.
- Chowdhury, Rajoshree Roy,Crane, Angela K.,Fowler, Candace,Kwong, Philip,Kozak, Christopher M.
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- Iron nanoparticles in the coupling of alkyl halides with aryl Grignard reagents
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Iron nanoparticles, either formed in situ stabilized by 1,6-bis(diphenylphosphino)hexane or polyethylene glycol (PEG), or preformed stabilized by PEG, are excellent catalysts for the cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens and they also prove effective in a tandem cyclization/cross- coupling reaction. The Royal Society of Chemistry 2006.
- Bedford, Robin B.,Betham, Michael,Bruce, Duncan W.,Davis, Sean A.,Frost, Robert M.,Hird, Michael
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p. 1398 - 1400
(2008/02/03)
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- Iron-phosphine, -phosphite, -arsine, and -carbene catalysts for the coupling of primary and secondary alkyl halides with aryl grignard reagents
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Simple catalysts formed in situ from iron chloride and a wide range of monodentate and bidentate phosphines and arsines have been screened in the coupling of alkyl halides bearing β-hydrogens with aryl Grignard reagents. The best of these show excellent activity, as do catalysts formed in situ with monodentate trialkyl and triaryl phosphite ligands. N-heterocyclic carbene-based precatalysts, either preformed or made in situ, also show excellent performance.
- Bedford, Robin B.,Betham, Michael,Bruce, Duncan W.,Danopoulos, Andreas A.,Frost, Robert M.,Hird, Michael
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p. 1104 - 1110
(2007/10/03)
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- Simple iron-amine catalysts for the cross-coupling of aryl Grignards with alkyl halides bearing β-hydrogens
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Mixtures of iron(III) chloride and appropriate amine ligands are active catalysts for the coupling of aryl Grignard reagents with primary and secondary alkyl halide substrates bearing β-hydrogens, under mild and simple reaction conditions. The Royal Society of Chemistry 2005.
- Bedford, Robin B.,Bruce, Duncan W.,Frost, Robert M.,Hird, Michael
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p. 4161 - 4163
(2007/10/03)
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- Iron-catalyzed grignard cross-coupling with alkyl halides possessing β-hydrogens
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Tris(acetylacetonato)iron(III) (Fe(acac)3) was found to be an efficient catalyst for the cross-coupling reaction between aryl Grignard reagents and alkyl halides possessing β-hydrogens. The reaction is applicable to secondary alkyl halides as well as primary ones.
- Nagano, Takashi,Hayashi, Tamio
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p. 1297 - 1299
(2007/10/03)
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- Synthesis of 1-Arylalk-2-enes and 1-Arylalkanes via Friedel-Crafts Alkylation with Allylic Alcohols Catalysed by an Acidic Clay
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Moderately activated benzenoid compounds undergo alkylation with allylic alcohols in the presence of acidic K10 clay to give almost exclusively 1-arylalk-2-enes by attack at the terminal position of the intermediate allyl cation; catalytic hydrogenation yields the corresponding 1-arylalkanes.
- Smith, Keith,Pollaud, Guy M
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p. 3519 - 3520
(2007/10/02)
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