- Synthesis and characterization of Di- and tetracarbene iron(II) complexes with chelating N-heterocyclic carbene ligands and their application in aryl Grignard-Alkyl halide cross-coupling
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A series of new and known bis(imidazolium) chloride and bromide salts bridged by either a methylene group (1-8, 10a,b) or an ethylene group (9a,b) and bearing different N substituents (Me, Et, Bn, tBu, Mes) have been reacted with [Fe{N(SiMe3)2}2]2 to yield the four-coordinate iron(II) complexes [LFeX2] (11-20; X = Cl, Br; L = chelating bis(imidazolylidene) ligand). Molecular structures of six of these complexes have been characterized by X-ray crystallography, and selected examples have been characterized by 1H NMR and UV-vis spectroscopy, cyclic voltammetry, Moessbauer spectroscopy, and SQUID magnetometry. In all cases the iron(II) is found in a distorted-tetrahedral environment; it is in the high-spin state and shows large quadrupole splittings in the range 3.67-4.03 mm?s-1 (δ = 0.73-0.81 mm?s-1). Subtleties of the metric parameters depend on the bridging unit between the two imidazolylidene groups, the peripheral N substituents, and the coligand (Cl or Br). In case of rather small (Me, Et) or flexible (Bn) N substituents the dicarbene species [LFeX2] are formed together with ferrous tetracarbene complexes [L2FeX2] (21-23), which are difficult to separate and could not be isolated in pure form. When the latter are dissolved in MeCN in the presence of residual [FeBr2(solv) x], however, they transform into the ionic complexes [L 2Fe(MeCN)2][FeBr4] (24-26), which have been characterized by single-crystal X-ray diffraction. They feature low-spin iron(II) (Moessbauer parameters δ ≈ 0.15 mm s-1, ΔEQ ≈ 1.36 mm s-1) and distorted-octahedral structures with the two MeCN ligands in a cis configuration. Selected examples of the new dicarbene complexes [LFeX2] have been tested as catalysts for the standard cross-coupling reaction between p-tolylmagnesium bromide and bromo- or chlorocyclohexane. They show moderate activity that appears to be generally lower than for related complexes with two monodentate NHC ligands, but the activities clearly depend on the peripheral N substituents and the linker between the two imidazolylidene groups; the best results are obtained for complex 19, which features a long ethylene bridge and bulky Mes substituents, and hence the most shielded metal center.
- Meyer, Steffen,Orben, Claudia Manuela,Demeshko, Serhiy,Dechert, Sebastian,Meyer, Franc
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Read Online
- The influence of the ligand chelate effect on iron-amine-catalysed Kumada cross-coupling
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The application of a variety of iron complexes with chelating amine ligands as pre-catalysts in the representative cross-coupling of 4-tolylmagnesium bromide with cyclohexyl bromide was investigated. The results from this study indicate the performance of the pre-catalyst is inversely proportional to the strength of the chelate or macrocyclic effect of the amine ligand, as determined by the propensity of the ligand to be displaced from the iron centre by reaction with excess benzyl magnesium chloride. The findings from this study are consistent with a catalytic cycle wherein the chelating amine ligand is not coordinated to the iron centre during turnover.
- Bedford, Robin B.,Brenner, Peter B.,Elorriaga, David,Harvey, Jeremy N.,Nunn, Joshua
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Read Online
- Dilithium Amides as a Modular Bis-Anionic Ligand Platform for Iron-Catalyzed Cross-Coupling
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Dilithium amides have been developed as a bespoke and general ligand for iron-catalyzed Kumada-Tamao-Corriu cross-coupling reactions, their design taking inspiration from previous mechanistic and structural studies. They allow for the cross-coupling of alkyl Grignard reagents with sp2-hybridized electrophiles as well as aryl Grignard reagents with sp3-hybridized electrophiles. This represents a rare example of a single iron-catalyzed system effective across diverse coupling reactions without significant modification of the catalytic protocol, as well as remaining operationally simple.
- Neate, Peter G.N.,Zhang, Bufan,Conforti, Jessica,Brennessel, William W.,Neidig, Michael L.
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supporting information
p. 5958 - 5963
(2021/08/18)
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- Visible-Light-Promoted Iron-Catalyzed C(sp2)–C(sp3) Kumada Cross-Coupling in Flow
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A continuous-flow, visible-light-promoted method has been developed to overcome the limitations of iron-catalyzed Kumada–Corriu cross-coupling reactions. A variety of strongly electron rich aryl chlorides, previously hardly reactive, could be efficiently coupled with aliphatic Grignard reagents at room temperature in high yields and within a few minutes’ residence time, considerably enhancing the applicability of this iron-catalyzed reaction. The robustness of this protocol was demonstrated on a multigram scale, thus providing the potential for future pharmaceutical application.
- Wei, Xiao-Jing,Abdiaj, Irini,Sambiagio, Carlo,Li, Chenfei,Zysman-Colman, Eli,Alcázar, Jesús,No?l, Timothy
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supporting information
p. 13030 - 13034
(2019/07/18)
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- Cross-Coupling Reactions of Alkyl Halides with Aryl Grignard Reagents Using a Tetrachloroferrate with an Innocent Countercation
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Bis(triphenylphosphoranylidene)ammonium tetrachloroferrate, (PPN)[FeCl4] (1), was evaluated as a catalyst for cross-coupling reactions. 1 exhibits high stability toward air and moisture and is an effective catalyst for the reaction of secondary alkyl halides with aryl Grignard reagents. The PPN cation is considered as an innocent counterpart to the iron center. We have developed an easy-to-handle iron catalyst for “ligand-free” cross-coupling reactions. (Figure presented.).
- Hashimoto, Toru,Maruyama, Tsubasa,Yamaguchi, Takamichi,Matsubara, Yutaka,Yamaguchi, Yoshitaka
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supporting information
p. 4232 - 4236
(2019/08/16)
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- 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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- Direct arylation of strong aliphatic C–H bonds
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Despite the widespread success of transition-metal-catalysed cross-coupling methodologies, considerable limitations still exist in reactions at sp3-hybridized carbon atoms, with most approaches relying on prefunctionalized alkylmetal or bromide coupling partners1,2. Although the use of native functional groups (for example, carboxylic acids, alkenes and alcohols) has improved the overall efficiency of such transformations by expanding the range of potential feedstocks3–5, the direct functionalization of carbon–hydrogen (C–H) bonds—the most abundant moiety in organic molecules—represents a more ideal approach to molecular construction. In recent years, an impressive range of reactions that form C(sp3)–heteroatom bonds from strong C–H bonds has been reported6,7. Additionally, valuable technologies have been developed for the formation of carbon–carbon bonds from the corresponding C(sp3)–H bonds via substrate-directed transition-metal C–H insertion8, undirected C–H insertion by captodative rhodium carbenoid complexes9, or hydrogen atom transfer from weak, hydridic C–H bonds by electrophilic open-shell species10–14. Despite these advances, a mild and general platform for the coupling of strong, neutral C(sp3)–H bonds with aryl electrophiles has not been realized. Here we describe a protocol for the direct C(sp3) arylation of a diverse set of aliphatic, C–H bond-containing organic frameworks through the combination of light-driven, polyoxometalate-facilitated hydrogen atom transfer and nickel catalysis. This dual-catalytic manifold enables the generation of carbon-centred radicals from strong, neutral C–H bonds, which thereafter act as nucleophiles in nickel-mediated cross-coupling with aryl bromides to afford C(sp3)–C(sp2) cross-coupled products. This technology enables unprecedented, single-step access to a broad array of complex, medicinally relevant molecules directly from natural products and chemical feedstocks through functionalization at sites that are unreactive under traditional methods.
- Perry, Ian B.,Brewer, Thomas F.,Sarver, Patrick J.,Schultz, Danielle M.,DiRocco, Daniel A.,MacMillan, David W. C.
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- Sterically congested phosphonium borate acids as effective Br?nsted acid catalysts
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Phosphonium borate acids [HPPh2(C6F5)][B(C6F5)4] (2), [HPMes2(C6F5)][B(C6F5)4] (3) and [HPMes(C6F5)2][B(C6F5)4] (4) were synthesized via heterolytic dihydrogen cleavage in the presence of triisopropylsilylium and characterized by spectroscopic and crystallographic methods. Br?nsted acid catalysis using compounds 2–4 proved to be efficient for a number of challenging reactions (namely ionic hydrogenation, hydroamination and hydroarylation), owing to the restrained nucleophilicity of the sterically hindered conjugate bases. Reactivity of compounds 2–4 suggests that their pKavalues are similar to that of diethyl oxonium acid.
- Sinha, Arup,Jaiswal, Amit K.,Young, Rowan D.
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- Nickel-catalyzed selective oxidative radical cross-coupling: An effective strategy for inert Csp3-H functionalization
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An effective strategy for inert Csp3-H functionalization through nickel-catalyzed selective radical cross-couplings was demonstrated. Density functional theory calculations were conducted and strongly supported the radical cross-coupling pathway assisted by nickel catalyst, which was further confirmed by radical-trapping experiments. Different arylborates including arylboronic acids, arylboronic acid esters and 2,4,6-triarylboroxin were all good coupling partners, generating the corresponding Csp3-H arylation products in good yields.
- Liu, Dong,Li, Yuxiu,Liu, Chao,Lei, Aiwen,Qi, Xiaotian,Lan, Yu.
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supporting information
p. 998 - 1001
(2015/03/30)
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- Imidazolidinium ferrate complexes: Synthesis and catalytic properties
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The new well-defined and air stable anionic iron complexes bearing an imidazolidinium ligand (2a-d) have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction studies. Starting from FeBr2, [imidazolidinium][FeBr4] complexes 2a and 2b were prepared. The reaction of imidazolidinium chlorides with Fe(OAc)2, followed by a recrystallization in the air led to bis(imidazolidinium) μ-oxido-bis[trichloroferrate(III)] complexes 2c and 2d. The catalytic activity of these novel complexes has been evaluated in the cross-coupling reactions of alkyl halides with Grignard reagents.
- Demir, Serpil,G?k?e, Yasemin,Roisnel, Thierry,Sortais, Jean-Baptiste,Darcel, Christophe,?zdemir, Ismail
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p. 541 - 548
(2014/06/09)
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- Iron-catalyzed arene alkylation reactions with unactivated secondary alcohols
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A simple, iron-based catalytic system allows for the inter- and intramolecular arylation of unactivated secondary alcohols. This transformation expands the substrate scope beyond the previously required activated alcohols and proceeds under mild reaction conditions, tolerating air and moisture. Furthermore, the use of an enantioenriched secondary alcohol provides an enantioenriched product for the intramolecular reaction, thereby offering a convenient approach to nonracemic products.
- Jefferies, Latisha R.,Cook, Silas P.
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supporting information
p. 2026 - 2029
(2014/05/06)
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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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- Reduction of aromatic compounds with Al powder using noble metal catalysts in water under mild reaction conditions
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In water, Al powder becomes a powerful reducing agent, transforming in cyclohexyl either one or both benzene rings of aromatic compounds such as biphenyl, fluorene and 9,10-dihydroanthracene under mild reaction conditions in the presence of noble metal catalysts, such as Pd/C, Rh/C, Pt/C, or Ru/C. The reaction is carried out in a sealed tube, without the use of any organic solvent, at low temperature. Partial aromatic ring reduction was observed when using Pd/C, the reaction conditions being 24 h and 60 °C. The complete reduction process of both aromatic rings required 12 h and 80 °C with Al powder in the presence of Pt/C.
- Rayhan, Ummey,Kwon, Hyeokmi,Yamato, Takehiko
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p. 952 - 957
(2014/08/18)
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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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- Simplifying iron-phosphine catalysts for cross-coupling reactions
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Any old iron? Iron catalysts based on the widely available diphosphine ligand bis(diphenylphosphino)ethane have not previously fared particularly well in iron-catalyzed cross-coupling processes. However, this turns out not to be due to any inherently poor performance associated with the ligand, but rather the need to form a bis-chelate complex, either before or during the formation of an active FeI species. Copyright
- Bedford, Robin B.,Carter, Emma,Cogswell, Paul M.,Gower, Nicholas J.,Haddow, Mairi F.,Harvey, Jeremy N.,Murphy, Damien M.,Neeve, Emily C.,Nunn, Joshua
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supporting information
p. 1285 - 1288
(2013/03/13)
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- IRON BISPHENOLATE COMPLEXES AND METHODS OF USE AND SYNTHESIS THEREOF
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The present application, relates to iron bisphenolate complexes and methods of use and synthesis thereof. The iron complexes are prepared from tridentate or tetradentate ligands of Formula I: wherein R1 and R2 are as defined herein. Also provided are methods and processes of using the iron bisphenolate complexes as catalysts in cross-coupling reactions and in controlled radical polymerizations.
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Paragraph 00193-00195
(2013/04/25)
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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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- An unprecedented iron-catalyzed cross-coupling of primary and secondary alkyl Grignard reagents with non-activated aryl chlorides
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The use of N-heterocyclic carbene ligands in the iron-catalyzed cross-coupling of alkyl Grignards has allowed, for the first time, coupling of non-activated, electron rich aryl chlorides. Surprisingly, the tetrahydrate of FeCl2 was found to be a better pre-catalyst than anhydrous FeCl 2. Primary Grignard reagents coupled in excellent yields while secondary Grignard reagents coupled in modest yields. The use of acyclic secondary Grignard reagents resulted in the formation of isomers in addition to the desired product. These isomeric products were formed via reversible β-hydrogen elimination, indicating that the cross-coupling proceeds through an ionic pathway.
- Perry, Marc C.,Gillett, Amber N.,Law, Tyler C.
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experimental part
p. 4436 - 4439
(2012/09/25)
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- Synthesis of iron(III) complex bearing tridentate β-Aminoketonato Ligand: Application to iron-catalyzed cross-coupling reaction of arylmagnesium bromides with alkyl halides
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A tridentate β-aminoketonato iron complex was prepared by the reaction of lithium β-aminoketonato with FeCl3. This iron complex was found to be an efficient catalyst for the crosscoupling reaction between arylmagnesium bromides and alkyl halides.
- Yamaguchi, Yoshitaka,Ando, Hiroaki,Nagaya, Makoto,Hinago, Hideto,Ito, Takashi,Asami, Masatoshi
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supporting information; experimental part
p. 983 - 985
(2011/12/05)
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- Iron-catalyzed coupling of aryl grignard reagents with alkyl halides: A competitive hammett study
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Competing for electrophiles: The elusive iron-catalyzed C-C coupling reaction was investigated and analyzed by a Hammett study of the nucleophilic partner. This required finding conditions in which the iron catalyst is stable in the presence of an excess of the Grignard reagent. The selectivity- determining step seems to be the transmetalation, occurring either before or after the oxidative addition step (see scheme).
- Hedstroem, Anna,Bollmann, Ulla,Bravidor, Jenny,Norrby, Per-Ola
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experimental part
p. 11991 - 11993
(2011/12/01)
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- Catalytic alkylation of aryl Grignard reagents by iron(iii) amine-bis(phenolate) complexes
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Reaction of n-propylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H2L1, n-propylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H2L2, and benzylamino-N,N-bis(2-methylene-4-tert-butyl-6- methylphenol), H2L3, with anhydrous ferric chloride in the presence of base yields the products, [FeL1(μ-Cl)]2 (1), [FeL2(μ-Cl)]2 (2) and [FeL3(μ-Cl)]2 (3). In the solid state, these complexes exist as chloride-bridged dimers giving distorted trigonal bipyramidal iron(iii) ions. Reaction of H2L1 with FeBr 3, however, results in the formation of a tetrahedral iron(iii) complex possessing two bromide ligands. The amine-bis(phenolate) ligand is bidentate in this complex and bonds to the iron(iii) ion via the phenolate O-donors. The central amine donor is protonated, resulting in a quaternized ammonium fragment and the iron(iii) centre possesses a negative formal charge. As a result, this complex is zwitterionic and formulated as FeBr2L1H (4). Complex 1 is an air-stable, non-hygroscopic, single-component catalyst for C-C cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides, including chlorides. Good to excellent yields of cross-coupled products are obtained in diethyl ether at room temperature. In some cases where low yields are obtained under these conditions, the use of microwave-assisted heating of the reaction mixture can improve yields. The Royal Society of Chemistry 2011.
- Qian, Xin,Dawe, Louise N.,Kozak, Christopher M.
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experimental part
p. 933 - 943
(2011/04/23)
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- Structure and C-C cross-coupling reactivity of iron(III) complexes of halogenated amine-bis(phenolate) ligands
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The preparation of tetradentate amine-bis(phenol) proligands with dichloro and difluoro substituted phenol groups and their reaction with FeX3 (X = Cl or Br) is described. The compounds, 2-pyridylamino-N,N-bis(2-methylene- 4,6-dichlorophenol), H2[L1]; 2-pyridylamino-N,N-bis(2- methylene-4,6-difluorophenol), H2[L2]; dimethylaminoethylamino-N,N-bis(2-methylene-4,6-dichlorophenol), H 2[L3]; 2-tetrahydrofurfuryl-N,N-bis(2-methylene-4,6- dichlorophenol), H2[L4]; and methoxyethylamino-N,N-bis(2- methylene-4,6-dichlorophenol), H2[L5] were prepared in aqueous medium and obtained as white powders in good to excellent yield. Ten new iron(III) halide complexes supported by these tetradentate ligands are reported. Representative single crystal X-ray diffraction structures were obtained for H2[L1] and a water adduct of the iron(III) complex, aquachloro{2-pyridylamino-N,N-bis(2-methylene-4,6-dichlorophenolato)} iron(III), 2·H2O. The structure of the proligand H 2[L1] shows intramolecular hydrogen bonding. In the solid-state structure, the iron complex exhibits intermolecular hydrogen bonding between the water ligand and the phenolate oxygen of a neighbouring complex. The anhydrous complexes were studied for catalytic activity towards C-C cross-coupling of Grignard reagent nucleophiles with alkyl halide electrophiles.
- Reckling, Amy M.,Martin, Dana,Dawe, Louise N.,Decken, Andreas,Kozak, Christopher M.
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scheme or table
p. 787 - 794
(2011/03/20)
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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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- The first iron-catalysed aluminium-variant Negishi coupling: Critical effect of co-existing salts on the dynamic equilibrium of arylaluminium species and their reactivity
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The first example of an iron-catalysed Negishi coupling between arylaluminium reagents and alkyl halides illustrates that the co-existing salts highly influence the dynamic equilibrium of the organoaluminium species, and have a critical effect on the reactivity and selectivity of the coupling reaction.
- Kawamura, Shintaro,Ishizuka, Kentaro,Takaya, Hikaru,Nakamura, Masaharu
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supporting information; experimental part
p. 6054 - 6056
(2010/11/02)
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- A catalytic C-C bond-forming reaction between aliphatic fluorohydrocarbons and arylsilanes
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C-C coupling reactions between arylsilanes and alkylfluorides are efficiently catalyzed by disilyl cation 1. Primary as well as secondary alkylfluorides were quantitatively coupled with arylsilanes; however, in the case of tertiary fluorides, the hydrodef
- Luehmann, Nicole,Panisch, Robin,Mueller, Thomas
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experimental part
p. 533 - 537
(2010/10/19)
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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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- Direct cobalt-catalyzed cross-coupling between aryl and alkyl halides
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An operationally simple cross-coupling reaction between aryl halides and alkyl halides with high selectivity has been developed. The underlying domino process utilizes CoCl2/Me4-DACH as a catalyst system. The methodology exhibits hig
- Czaplik, Waldemar Maximilian,Mayer, Matthias,Jacobi Von Wangelin, Axel
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experimental part
p. 2931 - 2934
(2010/01/21)
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- PROCESS FOR PREPARING ORGANIC COMPOUNDS BY A TRANSITION METAL-CATALYSED CROSS-COUPLING REACTION OF AN ARYL-X, HETEROARYL-X, CYCLOALKENYL-X OR ALKENYL-X COMPOUND WITH AN ALKYL, ALKENYL, CYCLOALKYL OR CYCLOALKENYL HALIDE
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A process for preparing organic compounds of the general formula (I) [in-line-formulae]R—R′??(I),[/in-line-formulae] where R is a substituted or unsubstituted aromatic, heteroaromatic, cycloalkenylic or alkenylic radical andR′ is a substituted or unsubstituted alkylic, alkenylic, cycloalkylic or cycloalkenylic radical, by reacting a corresponding compound of the general formula (II) [in-line-formulae]R—X??(II),[/in-line-formulae] where X is chlorine, bromine, iodine, diazonium, mesylate (methanesulphonate), tosylate (p-toluenesulphonate) or triflate (trifluorosutphonate) andR is as defined for formula (I), with a corresponding compound of the general formula (III) [in-line-formulae]R′—Y??(III),[/in-line-formulae] where Y is chlorine, bromine or iodine andR′ is as defined for formula (I), wherein the reaction is carried out in the presence of a) stoichiometric amounts of elemental magnesium, based on the compound of the general formula (II), andb) catalytic amounts of a transition metal compound, based on the compound of the general formula (II), and, if appropriate, c) in the presence of a nitrogen-, oxygen- and/or phosphorus-containing additive in a catalytic or stoichiometric amount, based on the compound of the general formula (II), is described. It is particularly advantageous that the process of the invention is carried out as a one-pot reaction and the organomagnesium compound (Grignard compound) formed in situ as intermediate is not isolated.
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Page/Page column 6
(2009/10/06)
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- Domino iron catalysis: Direct aryl-alkyl cross-coupling
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(Chemical Equation Presented) Striking while the iron is hot: Cheap FeCl3 serves as the precatalyst for the direct cross-coupling of aryl and alkyl halides that is based on the sequence of Grignard formation and subsequent cross-coupling. This
- Czaplik, Waldemar Maximilian,Mayer, Matthias,Von Wangelin, Axel Jacobi
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supporting information; experimental part
p. 607 - 610
(2009/04/14)
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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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- Nitrosonium salts, NO+X- (X = B(3,5-diCF 3Ph)4- or PW12O40 3-), as electrophilic catalysts for alkene activation in arene alkylation and dimerization reactions
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It has been found that in apolar reaction media the nitrosonium cation (NO+) activated alkenes under mild conditions toward electrophilic substitution of arene substrates to yield the alkylated arene with Markovnikov orientation. In the absence of arenes the alkenes react with themselves to yield a mixture of dimeric alkenes. The nitrosonium cation can be dissolved in the reaction medium by using the tetrakis-(bis-(3,5-trifluromethyl)phenyl) borate anion, where upon the reactions occur effectively at 30 °C. Alternatively an insoluble, heterogeneous catalyst was prepared so as to yield a NO+ cation with a polyoxometalate (PW12O403-) anion. This catalyst was generally more effective and selective toward a broader range of substrates at 70 °C. Copyright
- Khenkin, Alexander M.,Neumann, Ronny
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supporting information; scheme or table
p. 11876 - 11877
(2009/02/05)
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- Preparation, structure, and reactivity of nonstabilized organoiron compounds. Implications for iron-catalyzed cross coupling reactions
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A series of unprecedented organoiron complexes of the formal oxidation states -2, 0, +1, +2, and +3 is presented, which are largely devoid of stabilizing ligands and, in part, also electronically unsaturated (14-, 16-, 17- and 18-electron counts). Specifically, it is shown that nucleophiles unable to undergo β-hydride elimination, such as MeLi, PhLi, or PhMgBr, rapidly reduce Fe(3+) to Fe(2+) and then exhaustively alkylate the metal center. The resulting homoleptic organoferrate complexes [(Me4Fe)(MeLi)] [Li(OEt2)]2 (3) and [Ph4Fe][Li(Et 2O)2][Li(1,4-dioxane)] (5) could be characterized by X-ray crystal structure analysis. However, these exceptionally sensitive compounds turned out to be only moderately nucleophilic, transferring their organic ligands to activated electrophiles only, while being unable to alkylate (hetero)aryl halides unless they are very electron deficient. In striking contrast, Grignard reagents bearing alkyl residues amenable to β-hydride elimination reduce FeXn (n = 2, 3) to clusters of the formal composition [Fe(MgX)2]n. The behavior of these intermetallic species can be emulated by structurally well-defined lithium ferrate complexes of the type [Fe(C2H4) 4][Li(tmeda)]2 (8), [Fe(cod)2][Li(dme)] 2 (9), [CpFe(C2H4)2][Li(tmeda)] (7), [CpFe(cod)][Li(dme)] (11), or [Cp*Fe(C2H4) 2][Li(tmeda)] (14). Such electron-rich complexes, which are distinguished by short intermetallic Fe-Li bonds, were shown to react with aryl chlorides and allyl halides; the structures and reactivity patterns of the resulting organoiron compounds provide first insights into the elementary steps of low valent iron-catalyzed cross coupling reactions of aryl, alkyl, allyl, benzyl, and propargyl halides with organomagnesium reagents. However, the acquired data suggest that such C-C bond formations can occur, a priori, along different catalytic cycles shuttling between metal centers of the formal oxidation states Fe(+1)/Fe(+3), Fe(0)/Fe(+2), and Fe(-2)/Fe(0). Since these different manifolds are likely interconnected, an unambiguous decision as to which redox cycle dominates in solution remains difficult, even though iron complexes of the lowest accessible formal oxidation states promote the reactions most effectively.
- Fuerstner, Alois,Martin, Ruben,Krause, Helga,Seidel, Guenter,Goddard, Richard,Lehmann, Christian W.
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p. 8773 - 8787
(2008/12/23)
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- An iron-containing ionic liquid as recyclable catalyst for aryl Grignard cross-coupling of alkyl halides
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The ionic liquid butylmelhylimidazolium tetrachloroferrate (bmim-FeCl 4) was found to be a very effective and completely air stable catalyst for the biphasic Grignard cross-coupling with primary and secondary alkyl halides bearing β-hydrogens. After simply decanting the product in the ethereal layer, the ionic liquid catalyst was successfully recycled four times.
- Bica, Katharina,Gaertner, Peter
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p. 733 - 735
(2007/10/03)
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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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- 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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- PROCESS FOR PRODUCTION OF AROMATIC COMPOUNDS
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A problem of the present invention is to provide an economical process with minimized toxicity for producing an aromatic compound having a variety of substituents such as various alkyl groups, and the problem is solved by a process for production of an aromatic compound represented by formula (1) below, which comprises reacting a compound represented by formula (2) below with an aromatic magnesium reagent represented by formula (3a) below in the presence of an iron catalyst and a diamine compound: wherein R is an optionally substituted hydrocarbon group or a C 3 - C 10 saturated or unsaturated ring group; A is an optionally substituted C 4 - C 20 aromatic group or an optionally substituted heteroaromatic group; X is a halogen atom or a sulfonic acid ester; and Y 1 is bromine, iodine, chlorine or a carbanion ligand.
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Page/Page column 20-23
(2010/11/24)
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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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- Alkylation on graphite in the absence of Lewis acids
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Graphite is introduced as a convenient catalyst for alkylation of aromatic compounds and alcohols by benzyl, tertiary alkyl, and secondary alkyl halides in the absence of strong Lewis acids. Primary alkyl halides are not active under the reaction conditions.
- Sereda, Grigoriy A.
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p. 7265 - 7267
(2007/10/03)
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- Iron-Catalyzed Cross-Coupling of Primary and Secondary Alkyl Halides with Aryl Grignard Reagents
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An iron-catalyzed cross-coupling reaction of a primary or secondary alkyl halide with an aryl Grignard reagent proceeds under mild conditions to give the corresponding coupling product in quantitative yield. Copyright
- Nakamura, Masaharu,Matsuo, Keiko,Ito, Shingo,Nakamura, Eiichi
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p. 3686 - 3687
(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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- Clean-chemistry synthesis of 2-tetralones in a single-stage acylation - Cycloalkylation process
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The preparation of substituted-2-tetralones by direct reaction of a 1-alkene with a substituted phenylacetic acid in a reaction system of trifluoroacetic anhydride (TFAA) and phosphoric acid is described. This single-stage process involves in situ formation of a mixed anhydride of the phenylacetic acid and acylation of the alkene by this species followed by cycloalkylation of the aromatic ring. This is a cleaner approach to the synthesis of 2-tetralones compared to Friedel-Crafts aliphatic acylation-cycloalkylation in that use of thionyl chloride, aluminum trichloride, and a chlorinated hydrocarbon solvent is eliminated. In addition, the atom efficiency is augmented by recovery of the spent TFAA as trifluoroacetic acid (TFA) and conversion of this back to TFAA by dehydration.
- Gray,Smyth
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p. 7113 - 7117
(2007/10/03)
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- An efficient method for aromatic Friedel-Crafts alkylation, acylation, benzoylation, and sulfonylation reactions
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Aromatic electrophilic substitution reactions such as alkylation, acylation, benzoylation, and sulfonylation were studied in the presence of a catalytic amount of Cu(OTf)2 and Sn(OTf)2. Cu(OTf)2 was very efficient for alkylation, acylation, and benzoylation reactions. However, in case of sulfonylation reactions, Sn(OTf)2 gave better results.
- Singh, Ravi P,Kamble, Rajesh M,Chandra, Kusum L,Saravanan,Singh, Vinod K
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p. 241 - 247
(2007/10/03)
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- Montmorillonite clay catalyzed tosylation of alcohols and selective monotosylation of diols with p-toluenesulfonic acid: An enviro-economic route
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An enviro-economic route for tosylation of alcohols and selective monotosylation of diols in good yield directly using p-toluenesulfonic acid together with metal-exchanged montmorillonite instead of p-toluenesulfonyl chloride or p-toluenesulfonic anhydrid
- Choudary, Boyapati M.,Chowdari, Naidu S.,Kantam, Mannepalli L.
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p. 7291 - 7298
(2007/10/03)
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- Contributions of enthalpy and entropy factors to isomerization equilibrium of isopropyl- and cyclohexylbenzenes
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Experimental and theoretical data on the liquid-phase equilibrium of the positional isomerization of isopropyl- and cyclohexylbenzenes are analyzed in detail. Contributions of the enthalpy and entropy factors to the equilibrium constants of the ortho-meta and para-meta transformations are estimated.
- Nesterova,Pimerzin,Krasnykh
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p. 1884 - 1890
(2007/10/03)
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- Novel reductive Friedel-Crafts alkylation of aromatics catalyzed by indium compounds: Chemoselective utilization of carbonyl moieties as alkylating reagents
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Reductive Friedel-Crafts alkylation of aromatics with ketones or aldehydes was characteristically catalyzed by indium compounds in preference to general catalysts like AlCl3 and BF3, where hydrosilanes would play an important role both as a hydride donor and as a co-catalyst. Chemoselective utilization of ketone moieties as alkylating reagents took place even in the presence of halogen, ester or ether moieties which are very susceptible under traditional Friedel-Crafts conditions. Discussion on a plausible intermediate was carried out by some controlled experiments.
- Miyai, Takashi,Onishi, Yoshiyuki,Baba, Akio
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p. 1017 - 1026
(2007/10/03)
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- Detailed Characterization of p-Toluenesulfonic Acid Monohydrate as a Convenient, Recoverable, Safe, and Selective Catalyst for Alkylation of the Aromatic Nucleus
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Alkylation of the aromatic nucleus, an important reaction in industry and synthetic organic chemistry, has traditionally been carried out by the well-known Friedel-Crafts reaction employing Lewis acid catalysts such as AlCl3 and BF3 or by using highly reactive organometallic reagents. Although protic acids such as anhydrous HF and concentrated H2SO4 have also been used in the alkylation of the aromatic nucleus, the notoriously corrosive, highly toxic, and hazardous nature of these agents has precluded their common use under ordinary laboratory conditions. Various organic sulfonic acids have, on occasion, been used as catalysts in Friedel-Crafts alkylations, but to our knowledge the chemistry and the scope of these reactions for common laboratory use have never been exploited in detail. In the present study we have characterized commercially available p-toluenesulfonic acid monohydrate (TsOH) as an efficient catalyst for the intermolecular coupling of the aromatic nucleus with activated alkyl halides, alkenes, or tosylates under mild conditions in an open atmosphere. In comparison to conventional Friedel-Crafts catalysts such as AlCl3, BF3, HF, and concentrated H2SO4, the extent of the formation of undesired products from side reactions such as transalkylation, polymerization, etc. was minimal with the TsOH-catalyzed reaction. The ability to recover and reuse the catalyst from the reaction mixtures, minimal generation of environmentally unfriendly waste, high specificity of the reaction, and the low cost of the catalyst are important advantages of the TsOH catalyst over the other conventional Friedel-Crafts catalysts.
- Mahindaratne, Mathew P. D.,Wimalasena, Kandatege
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p. 2858 - 2866
(2007/10/03)
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- Indium trichloride catalyzed reductive Friedel-Crafts alkylation of aromatics using carbonyl compounds
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Reductive Friedel-Crafts alkylation of aromatics with aldehydes or ketones using chlorodimethylsilane as a hydride source was effectively promoted by a catalytic amount of indium trichloride, whereas a popular type of Friedel-Crafts catalysts showed less effect.
- Miyai, Takashi,Onishi, Yoshiyuki,Baba, Akio
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p. 6291 - 6294
(2007/10/03)
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- Hydrogenation of Biphenyls over the Hydrogen Storage Alloy MmNi3.5Co0.7Al0.8H4
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Hydrogenation of biphenyl with the activated hydrogen storage alloy, MmNi3.5Co0.7Al0.8H4 (Mm: La, 30; Ce, 52; Pr, 5; Nd, 13 wtpercent), as a stoichiometric reductant proceeded effectively at 160 deg C for 3 h under nitrogen to give either phenylcyclohexane or bicyclohexyl selectively, according to the ratio of the alloy to biphenyl.
- Nakagawa, Shin-ichi,Murata, Satoru,Sakai, Tetsuo,Nomura, Masakatsu
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p. 431 - 432
(2007/10/02)
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- Catalysis of Friedel-Crafts Alkylation by a Montmorillonite Doped with Transition-Metal Cations
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Catalysts are obtained by exchange of the interstitial cations in the K10 montmorillonite.They are applied to Friedel-Crafts alkylations with halides, alcohols, and olefins.They are quite effective even with unactivated hydrocarbons.Isomer distribution depends little on the catalyst used.Thermodynamic equilibration does not take place, the reactions appear to be kinetically controlled.Efficiency of the catalysts bears no apparent relation to that of the corresponding Lewis acids under homogeneous conditions, and it depends on the nature of the alkylating agent.Zr(IV) and Ti(IV), in general, give the best results.
- Laszlo, Pierre,Mathy, Arthur
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p. 577 - 586
(2007/10/02)
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