- Benzene Alkylation with Cycloolefins under the Action of [Et3NH]+[Al2Cl7]? Ionic Liquid
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Benzene alkylation with mono- and bicyclic olefins under the action of an inorganic ionic liquid [Et3NH]+[Al2Cl7]? with the formation of benzene cycloalkyl derivatives in 58–98% yield has been performed for the first time. It has been found that the increase in the olefin cycle size improves the selectivity with respect to monocycloalkyl derivatives.
- Aminov,Mazitova,Khusnutdinov
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p. 2171 - 2177
(2020/01/08)
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- Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
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Redox noninnocent ligands are a promising tool to moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2-10 bar, 20-80 °C) by use of the stable catalyst precursor [(DippBIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic studies support a homogeneous catalysis pathway involving alkene and hydrido cobaltates as active catalyst species. Furthermore, considerable reaction acceleration by alkali cations and Lewis acids was observed. The dinuclear hydridocobaltate anion with bridging hydride ligands was isolated and fully characterized.
- Sandl, Sebastian,Maier, Thomas M.,Van Leest, Nicolaas P.,Kr?ncke, Susanne,Chakraborty, Uttam,Demeshko, Serhiy,Koszinowski, Konrad,De Bruin, Bas,Meyer, Franc,Bodensteiner, Michael,Herrmann, Carmen,Wolf, Robert,Von Jacobi Wangelin, Axel
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p. 7596 - 7606
(2019/08/20)
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- Amine-Borane Dehydrogenation and Transfer Hydrogenation Catalyzed by α-Diimine Cobaltates
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Anionic α-diimine cobalt complexes, such as [K(thf)1.5{(DippBIAN)Co(η4-cod)}] (1; Dipp=2,6-diisopropylphenyl, cod=1,5-cyclooctadiene), catalyze the dehydrogenation of several amine-boranes. Based on the excellent catalytic properties, an especially effective transfer hydrogenation protocol for challenging olefins, imines, and N-heteroarenes was developed. NH3BH3 was used as a dihydrogen surrogate, which transferred up to two equivalents of H2 per NH3BH3. Detailed spectroscopic and mechanistic studies are presented, which document the rate determination by acidic protons in the amine-borane.
- Maier, Thomas M.,Sandl, Sebastian,Shenderovich, Ilya G.,Jacobi von Wangelin, Axel,Weigand, Jan J.,Wolf, Robert
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supporting information
p. 238 - 245
(2019/01/04)
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- Teaching an old carbocation new tricks: Intermolecular C-H insertion reactions of vinyl cations
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Vinyl carbocations have been the subject of extensive experimental and theoretical studies over the past five decades. Despite this long history in chemistry, the utility of vinyl cations in chemical synthesis has been limited, with most reactivity studies focusing on solvolysis reactions or intramolecular processes. Here we report synthetic and mechanistic studies of vinyl cations generated through silylium-weakly coordinating anion catalysis. We find that these reactive intermediates undergo mild intermolecular carbon-carbon bond-forming reactions, including carbon-hydrogen (C-H) insertion into unactivated sp3 C-H bonds and reductive Friedel-Crafts reactions with arenes. Moreover, we conducted computational studies of these alkane C-H functionalization reactions and discovered that they proceed through nonclassical, ambimodal transition structures. This reaction manifold provides a framework for the catalytic functionalization of hydrocarbons using simple ketone derivatives.
- Popov, Stasik,Shao, Brian,Bagdasarian, Alex L.,Benton, Tyler R.,Zou, Luyi,Yang, Zhongyue,Houk,Nelson, Hosea M.
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p. 381 - 387
(2018/08/07)
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- Olefin-Stabilized Cobalt Nanoparticles for C=C, C=O, and C=N Hydrogenations
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The development of cobalt catalysts that combine easy accessibility and high selectivity constitutes a promising approach to the replacement of noble-metal catalysts in hydrogenation reactions. This report introduces a user-friendly protocol that avoids complex ligands, hazardous reductants, special reaction conditions, and the formation of highly unstable pre-catalysts. Reduction of CoBr2 with LiEt3BH in the presence of alkenes led to the formation of hydrogenation catalysts that effected clean conversions of alkenes, carbonyls, imines, and heteroarenes at mild conditions (3 mol % cat., 2–10 bar H2, 20–80 °C). Poisoning studies and nanoparticle characterization by TEM, EDX, and DLS supported the notion of a heterotopic catalysis mechanism.
- Sandl, Sebastian,Schwarzhuber, Felix,P?llath, Simon,Zweck, Josef,Jacobi von Wangelin, Axel
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supporting information
p. 3403 - 3407
(2018/02/13)
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- A Manganese Nanosheet: New Cluster Topology and Catalysis
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While the coordination chemistry of monometallic complexes and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare owing to the strong preference for three-dimensional structures and rapid aggregation or decomposition. A simple ligand-exchange procedure has led to the formation of a novel heteroleptic Mn6 nanocluster that crystallized in an unprecedented flat-chair topology and exhibited unique magnetic and catalytic properties. Magnetic susceptibility studies documented strong electronic communication between the manganese ions. Reductive activation of the molecular Mn6 cluster enabled catalytic hydrogenations of alkenes, alkynes, and imines.
- Chakraborty, Uttam,Reyes-Rodriguez, Efrain,Demeshko, Serhiy,Meyer, Franc,Jacobi von Wangelin, Axel
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supporting information
p. 4970 - 4975
(2018/03/28)
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- Enantioselective Radical Cyclization for Construction of 5-Membered Ring Structures by Metalloradical C-H Alkylation
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Radical cyclization represents a powerful strategy for construction of ring structures. Traditional radical cyclization, which is based on radical addition as the key step, necessitates the use of unsaturated substrates. Guided by the concept of metalloradical catalysis, a different mode of radical cyclization that can employ saturated C-H substrates is demonstrated through the development of a Co(II)-based system for catalytic activation of aliphatic diazo compounds for enantioselective radical alkylation of various C(sp3)-H bonds. It allows for efficient construction of chiral pyrrolidines and other valuable 5-membered cyclic compounds. This alternative strategy of radical cyclization provides a new retrosynthetic paradigm to prepare five-membered cyclic molecules from readily available open-chain aldehydes through the union of C-H and C=O elements for C-C bond formation.
- Wang, Yong,Wen, Xin,Cui, Xin,Zhang, X. Peter
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p. 4792 - 4796
(2018/04/17)
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- Iron-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions between Alkyl Halides and Unactivated Arylboronic Esters
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An iron-catalyzed cross-coupling reaction between alkyl halides and arylboronic esters was developed that does not involve activation of the boronic ester with alkyllithium reagents nor requires magnesium additives. A combination of experimental and theoretical investigations revealed that lithium amide bases coupled with iron complexes containing deprotonated cyanobis(oxazoline) ligands were best to obtain high yields (up to 89%) in catalytic cross-coupling reactions. Mechanistic investigations implicate carbon-centered radical intermediates and highlight the critical importance of avoiding conditions that lead to iron aggregates. The new iron-catalyzed Suzuki-Miyaura reaction was applied toward the shortest reported synthesis of the pharmaceutical Cinacalcet.
- Crockett, Michael P.,Tyrol, Chet C.,Wong, Alexander S.,Li, Bo,Byers, Jeffery A.
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supporting information
p. 5233 - 5237
(2018/09/12)
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- Cross-coupling method of alkyl chloride and phenyl magnesium bromide
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The invention provides a cross-coupling method of an alkyl chloride and phenyl magnesium bromide, wherein a copper salt is used as a catalyst, the 2-methyltetrahydrofuran solution of phenyl magnesiumbromide is used as a coupling reagent, and the corss-coupling of the inactive secondary/tertiary alkyl chloride and the phenyl magnesium bromide is achieved. According to the present invention, the method has the high yield, does not require the addition of the ligand, is simple and easy to perform, and has important significance in the synthesis of complex molecules such as natural products, chiral drugs, and the like.
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Paragraph 0020; 0021; 0022
(2018/07/28)
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- Arylation of hydrocarbons enabled by organosilicon reagents and weakly coordinating anions
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Over the past 80 years, phenyl cation intermediates have been implicated in a variety of C-H arylation reactions. Although these examples have inspired several theoretical and mechanistic studies, aryl cation equivalents have received limited attention in organic methodology. Their high-energy, promiscuous reactivity profiles have hampered applications in selective intermolecular processes. We report a reaction design that overcomes these challenges. Specifically, we found that b-silicon-stabilized aryl cation equivalents, generated via silylium-mediated fluoride activation, undergo insertion into sp3 and sp2 C-H bonds. This reaction manifold provides a framework for the catalytic arylation of hydrocarbons, including simple alkanes such as methane. This process uses low loadings of Earth-abundant initiators (1 to 5 mole percent) and occurs under mild conditions (30° to 100°C).
- Shao, Brian,Bagdasarian, Alex L.,Popov, Stasik,Nelson, Hosea M.
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- Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings
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Here, we describe a photoredox-assisted catalytic system for the direct reductive coupling of two carbon electrophiles. Recent advances have shown that nickel catalysts are active toward the coupling of sp3-carbon electrophiles and that well-controlled, light-driven coupling systems are possible. Our system, composed of a nickel catalyst, an iridium photosensitizer, and an amine electron donor, is capable of coupling halocarbons with high yields. Spectroscopic studies support a mechanism where under visible light irradiation the Ir photosensitizer in conjunction with triethanolamine are capable of reducing a nickel catalyst and activating the catalyst toward cross-coupling of carbon electrophiles. The synthetic methodology developed here operates at low 1 mol % catalyst and photosensitizer loadings. The catalytic system also operates without reaction additives such as inorganic salts or bases. A general and effective sp2-sp3 cross-coupling scheme has been achieved that exhibits tolerance to a wide array of functional groups.
- Paul, Avishek,Smith, Mark D.,Vannucci, Aaron K.
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p. 1996 - 2003
(2017/02/26)
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- Copper-catalyzed cross-coupling reactions of non-activated primary, secondary or tertiary alkyl chlorides with phenylmagnesium bromide
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Efficient copper-catalyzed cross-coupling reactions of non-activated alkyl chlorides, including primary, secondary, and tertiary alkyl chlorides, with phenyl Grignard reagents were achieved. Preparation of phenylmagnesium bromide in 2-methyltetrahydrofuran is critical for the success of the reaction. This protocol expands the synthetic toolbox for the construction of C[sbnd]C bonds of non-activated primary, secondary, and tertiary alkyl chlorides via copper-catalyzed cross-coupling.
- Tao, Chuanzhou,Sun, Lei,Wang, Bin,Liu, Zhou,Zhai, Yadong,Zhang, Xiulian,Shi, Dahua,Liu, Weiwei
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supporting information
p. 305 - 308
(2017/01/03)
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- Nickel-Catalyzed Reductive Cross-Coupling of Aryl Bromides with Alkyl Bromides: Et3N as the Terminal Reductant
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Reductive cross-coupling has emerged as a direct method for the construction of carbon-carbon bonds. Most cobalt-, nickel-, and palladium-catalyzed reductive cross-coupling reactions to date are limited to stoichiometric Mn(0) or Zn(0) as the reductant. One nickel-catalyzed cross-coupling paradigm using Et3N as the terminal reductant is reported. By using this photoredox catalysis and nickel catalysis approach, a direct Csp2-Csp3 reductive cross-coupling of aryl bromides with alkyl bromides is achieved under mild conditions without stoichiometric metal reductants.
- Duan, Zhengli,Li, Wu,Lei, Aiwen
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supporting information
p. 4012 - 4015
(2016/08/30)
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- Nickel-Catalyzed Cross-Electrophile Coupling with Organic Reductants in Non-Amide Solvents
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Cross-electrophile coupling of aryl halides with alkyl halides has thus far been primarily conducted with stoichiometric metallic reductants in amide solvents. This report demonstrates that the use of tetrakis(dimethylamino)ethylene (TDAE) as an organic reductant enables the use of non-amide solvents, such as acetonitrile or propylene oxide, for the coupling of benzyl chlorides and alkyl iodides with aryl halides. Furthermore, these conditions work for several electron-poor heterocycles that are easily reduced by manganese. Finally, we demonstrate that TDAE addition can be used as a control element to ‘hold’ a reaction without diminishing yield or catalyst activity.
- Anka-Lufford, Lukiana L.,Huihui, Kierra M. M.,Gower, Nicholas J.,Ackerman, Laura K. G.,Weix, Daniel J.
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supporting information
p. 11564 - 11567
(2016/08/05)
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- Hydride Reduction by a Sodium Hydride-Iodide Composite
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Sodium hydride (NaH) is widely used as a Br?nsted base in chemical synthesis and reacts with various Br?nsted acids, whereas it rarely behaves as a reducing reagent through delivery of the hydride to polar π electrophiles. This study presents a series of reduction reactions of nitriles, amides, and imines as enabled by NaH in the presence of LiI or NaI. This remarkably simple protocol endows NaH with unprecedented and unique hydride-donor chemical reactivity.
- Too, Pei Chui,Chan, Guo Hao,Tnay, Ya Lin,Hirao, Hajime,Chiba, Shunsuke
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p. 3719 - 3723
(2016/03/26)
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- Photocatalytic decarboxylative reduction of carboxylic acids and its application in asymmetric synthesis
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The decarboxylative reduction of naturally abundant carboxylic acids such as α-amino acids and α-hydroxy acids has been achieved via visible-light photoredox catalysis. By using an organocatalytic photoredox system, this method offers a mild and rapid entry to a variety of high-value compounds including medicinally relevant scaffolds. Regioselective decarboxylation is achieved when differently substituted dicarboxylic acids are employed. The application of this method to the synthesis of enantioenriched 1-aryl-2,2,2-trifluoroethyl chiral amines starting from natural α-amino acids further testifies to the utility of the developed photocatalytic decarboxylative reduction protocol.
- Cassani, Carlo,Bergonzini, Giulia,Wallentin, Carl-Johan
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supporting information
p. 4228 - 4231
(2014/09/30)
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- Expedient iron-catalyzed coupling of alkyl, benzyl and allyl halides with arylboronic esters
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While attractive, the iron-catalyzed coupling of arylboron reagents with alkyl halides typically requires expensive or synthetically challenging diphosphine ligands. Herein, we show that primary and secondary alkyl bromides and chlorides, as well as benzyl and allyl halides, can be coupled with arylboronic esters, activated with alkyllithium reagents, by using very simple iron-based catalysts. The catalysts used were either adducts of inexpensive and widely available diphosphines or, in a large number of cases, simply [Fe(acac)3] with no added co- ligands. In the former case, preliminary mechanistic studies highlight the likely involvement of iron(I)-phosphine intermediates. More irons in the fire: Primary and secondary alkyl, benzyl and allyl halides were coupled with arylboronic esters by using very simple iron-based catalysts. These were either adducts of inexpensive and widely available diphosphines or, in a large number of cases, simply [Fe(acac)3] with no added co-ligands (see scheme; acac=acetylacetonate). In the former case, preliminary mechanistic studies highlight the likely involvement of low-coordinate iron(I)-phosphine intermediates.
- Bedford, Robin B.,Brenner, Peter B.,Carter, Emma,Carvell, Thomas W.,Cogswell, Paul M.,Gallagher, Timothy,Harvey, Jeremy N.,Murphy, Damien M.,Neeve, Emily C.,Nunn, Joshua,Pye, Dominic R.
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supporting information
p. 7935 - 7938
(2014/07/07)
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- Indium(III) triflate - A catalyst for greener aromatic alkylation reactions
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An environmentally friendly method for alkylating aromatic compounds with simple alcohols in the presence of a catalytic amount of indium(III) triflate is reported. Ionic liquids are used as solvents and energy-efficient heating is provided by microwave radiation. Good yields are obtained with benzyl, secondary, and tertiary alcohols. Simple primary alcohols are not effective alkylating agents under these conditions. With tertiary alcohols, activated aromatic compounds such as toluene and anisole must be used to obtain good yields. The catalyst, which is immobilized in a water-insoluble ionic liquid, can be easily recycled without significant loss of activity.
- Mack, Ryan,Askins, Grant,Lowry, Jacob,Hurley, Nathan,Reeves, Perry C.
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p. 1262 - 1265
(2014/01/06)
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- Replacing conventional carbon nucleophiles with electrophiles: Nickel-catalyzed reductive alkylation of aryl bromides and chlorides
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A general method is presented for the synthesis of alkylated arenes by the chemoselective combination of two electrophilic carbons. Under the optimized conditions, a variety of aryl and vinyl bromides are reductively coupled with alkyl bromides in high yields. Under similar conditions, activated aryl chlorides can also be coupled with bromoalkanes. The protocols are highly functional-group tolerant (-OH, -NHTs, -OAc, -OTs, -OTf, -COMe, -NHBoc, -NHCbz, -CN, -SO2Me), and the reactions are assembled on the benchtop with no special precautions to exclude air or moisture. The reaction displays different chemoselectivity than conventional cross-coupling reactions, such as the Suzuki-Miyaura, Stille, and Hiyama-Denmark reactions. Substrates bearing both an electrophilic and nucleophilic carbon result in selective coupling at the electrophilic carbon (R-X) and no reaction at the nucleophilic carbon (R-[M]) for organoboron (-Bpin), organotin (-SnMe3), and organosilicon (-SiMe2OH) containing organic halides (X-R-[M]). A Hammett study showed a linear correlation of σ and σ(-) parameters with the relative rate of reaction of substituted aryl bromides with bromoalkanes. The small ρ values for these correlations (1.2-1.7) indicate that oxidative addition of the bromoarene is not the turnover-frequency determining step. The rate of reaction has a positive dependence on the concentration of alkyl bromide and catalyst, no dependence upon the amount of zinc (reducing agent), and an inverse dependence upon aryl halide concentration. These results and studies with an organic reductant (TDAE) argue against the intermediacy of organozinc reagents.
- Everson, Daniel A.,Jones, Brittany A.,Weix, Daniel J.
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supporting information; experimental part
p. 6146 - 6159
(2012/05/07)
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- Cross-coupling of non-activated chloroalkanes with aryl grignard reagents in the presence of iron/N-heterocyclic carbene catalysts
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An efficient and high-yielding cross-coupling reaction of various primary, secondary, and tertiary alkyl chlorides with aryl Grignard reagents was achieved by using catalytic amounts of N-heterocyclic carbene ligands and iron salts. This reaction is a simple and efficient arylation method having applicability to a wide range of industrially abundant chloroalkanes, including polychloroalkanes, which are challenging substrates under conventional cross-coupling conditions.
- Ghorai, Sujit K.,Jin, Masayoshi,Hatakeyama, Takuji,Nakamura, Masaharu
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supporting information; experimental part
p. 1066 - 1069
(2012/04/10)
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- DEHYDROGENATION OF CYCLOHEXANONE TO PRODUCE PHENOL
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In a process for the dehydrogenation of cyclohexanone to produce phenol, a feed comprising cyclohexanone is contacted with a dehydrogenation catalyst under dehydrogenation conditions comprising a temperature of less than 4000C and a pressure of less than 690 kPa, gauge, such 0.1 to 50 wt% of the cyclohexanone in said feed is converted to phenol and the dehydrogenation product contains less than 100 ppm by weight of alkylbenzenes.
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Page/Page column 25
(2011/09/14)
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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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- Iron-catalyzed cross-coupling of alkyl sulfonates with arylzinc reagents
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Iron-catalyzed cross-coupling reactions of primary and secondary alkyl sulfonates with arylzinc reagents proceed smoothly In the presence of excess TMEDA and a concomitant magnesium salt. The arylzinc reagents are prepared from the corresponding aryllithium or magnesium reagents with ZnI2. The In situ formation of alkyl Iodides and consecutive rapid cross-coupling avoids discrete preparation of the unstable secondary alkyl halides and also achieves high product selectivity.
- Ito, Shingo,Fujiwara, Yu-Ichi,Nakamura, Eiichi,Nakamura, Masaharu
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supporting information; experimental part
p. 4306 - 4309
(2009/12/26)
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- Conversion of Weinreb Amides into Benzene Rings Incorporating the Amide Carbonyl Carbon
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Esters, acids and acid chlorides can be converted via the intermediacy of their corresponding Weinreb amides into benzene derivatives that incorporate the original carbonyl carbon as part of the benzene ring. The process involves treatment of the derived Weinreb amides with 3-butenylmagnesium bromide and an allylic Grignard reagent, followed by ring-closing metathesis, dehydration and dehydrogenation. The dehydration-dehydrogenation can be done under acidic conditions with a mixture of TsOH·H2O and DDQ or in two steps with SOCl2/pyridine, followed by treatment with DDQ. Application of the method to carbohydrates provides a convenient route to C-5 aryl pyranosides.
- Clive, Derrick L. J.,Pham, Mai P.
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supporting information; experimental part
p. 1685 - 1690
(2009/07/11)
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- PYRAZOLE DERIVATIVES AS ANTI-PLATELET AND ANTI-THROMBOTIC AGENTS
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This invention relates to novel compounds of formula (I) or stereoisomers or pharmaceutically acceptable salts thereof wherein Y, R1 through R9, and X1 through X7 are as defined in the specification, pharmaceutical compositions containing said compounds useful as P2Y1 antagonists, and to methods of treating thromboembolic disorders.
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Page/Page column 63
(2010/11/30)
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- Vanadium-catalyzed cross-coupling reactions of alkyl halides with aryl grignard reagents
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Vanadium(III) chloride catalyzed cross-coupling reactions of alkyl halides with arylmagnesium bromides. Various arylmagnesium bromides, except for an ortho-substituted arylmagnesium reagent, could be used for the reaction. Among alkyl halides tested, cyclohexyl halides and primary alkyl halides were good substrates. The reactions likely proceed via carbon-centered radical intermediates. 2008 The Chemical Society of Japan.
- Yasuda, Shigeo,Yorimitsu, Hideki,Oshima, Koichiro
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experimental part
p. 287 - 290
(2009/03/12)
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- Preparation of functionalized alkylmagnesium derivatives using an I/Mg-exchange
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Functionalized alkylmagnesium reagents bearing an acetal, a ketal, an ester, or a pyridine ring were prepared by an I/Mg-exchange using iPr 2Mg-LiCI or CIMg(CH2)5MgCI-2LiCI starting from functionalized primary alkyl iodides.
- Rauhut, Christian B.,Vu, Viet Anh,Fleming, Fraser F.,Knochel, Paul
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body text
p. 1187 - 1189
(2009/04/06)
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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-catalyzed alkylations of aromatic Grignard reagents
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(Chemical Equation Presented) Any old iron: Two efficient iron-catalyzed cross-coupling reactions between aryl Grignard reagents and alkyl bromides were developed that are suitable for large-scale applications. The first procedure uses iron acetylacetonate and involves a cooperative effect between the two ligands N,N,N′,N′-tetramethylethylenediamine (TMEDA) and hexamethylenetetraamine (HMTA), while the second procedure uses [(FeCl 3)2(tmeda)3] as catalyst. 2007 Wiley-VCH Verlag GmbH & Co. KGaA.
- Cahiez, Gerard,Habiak, Vanessa,Duplais, Christophe,Moyeux, Alban
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p. 4364 - 4366
(2008/03/12)
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- Novel acidic ionic liquids catalytic systems for friedel-crafts alkylation of aromatic compounds with alkenes
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Novel acidic ionic liquids catalytic systems are developed for the Friedel-Crafts alkylation of aromatic compounds with alkenes.
- Qiao, Kun,Yokoyama, Chiaki
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p. 472 - 473
(2007/10/03)
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- SOLVENTS CONTAINING CYCLOALKYL ALKYL ETHERS AND PROCESS FOR PRODUCTION OF THE ETHERS
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The present inventions are (A) a solvent comprising at least one cycloalkyl alkyl ether (1) represented by the general formula: R1-O-R2 (wherein R1 is cyclopentyl or the like; and R2 is C1-10 alkyl or the like); (B) a method of preparations the ethers (1) characterized by reacting an alicyclic olefin with an alcohol in the presence of an acid ion-exchange resin having a water content of 5 wt% or less. The solvent is useful as cleaning solvent for electronic components, precision machinery components or the like, reaction solvent using various chemical reactions, extraction solvent for extracting objective organic substances, solvent or remover for electronic and electrical materials, and so on. The process enables industrially advantageous production of the objective cycloalkyl alkyl ethers (1).
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- Hydrocarbon activation. Synthesis of β-cycloalkyl (Di)nitriles through photosensitized conjugate radical addition
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Photoinduced hydrogen abstraction from aliphatic cyclic hydrocarbons (C5 to C7, C12, as well as adamantane) by triplet aromatic ketones in the presence of α,β-unsaturated (di)nitriles offers a straightforward entry to the corresponding alkylated (di)nitriles via the alkyl radicals. Yields are moderate to good depending on the olefins structure (substitution in β slows down the addition to mononitriles, but with α,α-dinitriles electronic activation allows efficient alkylation also of β,β-disubstituted substrates). A tandem alkylation - cyclization process has been obtained with (1-methylpent-4-enylidene)malononitrile.
- Cardarelli,Fagnoni,Mella,Albini
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p. 7320 - 7327
(2007/10/03)
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- A convenient method for the reductive desulfonylation of some sulfones by the Sm/HOAc system
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Metallic samarium can be used in desulfonylation in the presence of glacial acetic acid. The reaction is illustrated here for nine substrates, which include α-phenylsulfonyl cinnamonitriles, β-ketosulfones and phenylsulfonyl cycloheptane.
- Guo,Zhang
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- Scandium(III) triflate immobilised in ionic liquids: a novel and recyclable catalytic system for Friedel-Crafts alkylation of aromatic compounds with alkenes
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Scandium(III) triflate catalysed Friedel-Crafts alkylation of aromatic compounds with alkenes proceeded readily in the hydrophobic ionic liquid solvents based on 1,3-dialkylimidazolium salts with easy catalyst/solvent recycling, whereas these reactions did not occur in common organic solvents, water or hydrophilic ionic liquids at all.
- Song, Choong Eui,Shim, Woo Ho,Roh, Eun Joo,Choi, Jung Hoon
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p. 1695 - 1696
(2007/10/03)
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- A new convenient Friedel-Crafts alkylation of aromatic compounds with secondary alcohol methanesulfonates in the presence of scandium(III) trifluoromethanesulfonate or trifluoromethanesulfonic acid as the catalyst
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Scandium(III) triflate and triflic acid were both found to be efficient catalysts for the Friedel-Crafts alkylation of aromatic compounds using methanesulfonates derived from secondary alcohols as alkylating agents.
- Kotsuki, Hiyoshizo,Ohishi, Takeshi,Inoue, Motoshi,Kojima, Tomoyuki
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p. 603 - 606
(2007/10/03)
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- Reductive free-radical alkylations and cyclisations mediated by 1-alkylcyclohexa-2,5-diene-1-carboxylic acids
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A range of 1-alkylcyclohexa-2,5-diene-1-carboxylic acids were prepared by Birch reduction-alkylation of benzoic acid and their efficiency as mediators of alkyl radical chain addition and cyclisation processes was investigated. Reductive alkylations were respectably successful, even with only one or two equivalents of alkene, for secondary, tertiary and benzylic radicals. Reaction of 1-[2-(cyclohex-2-enyloxy)ethyl]cyclohexa-2,5-diene-1-carboxylic acid yielded the product of exo-trig-cyclisation, i.e. 7-oxabicyclo[4.3.0]nonane, in a yield comparable to that obtained from the tributyltin hydride induced cyclisation of 3-(2′-iodoethoxy)-cyclohexene. This, together with the isolation of both exo- and endo-cyclisation products from 1-[2-(6,6-dimethylbicyclo[3.1.1]hept-2-en-2-ylmethoxy)ethyl]cyclohexa-2,5-diene- 1-carboxylic acid established that ring closures could also be satisfactorily mediated with these reagents. Preparations were completely free of metal contaminants and direct reduction of the alkyl radicals, prior to addition or cyclisation, was completely absent. However, the desired products were accompanied by alkylbenzenes, together with by-products from the initiator decompositions, and this complicated work-up. Failure to obtain 1-[2-(prop-2-yn-1-yloxy)cyclohexyl]cyclohexa-2,5-diene-1-carboxylic acid in Birch reductive alkylations with trans-1-iodo-2-(prop-2-yn-1-yloxy)cyclohexane (and the corresponding bromide) indicated a limitation on precursor synthesis. The Birch reduction-alkylation was not of universal applicability and was suppressed for alkyl halides having β-substituents.
- Baguley, Paul A.,Walton, John C.
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p. 2073 - 2082
(2007/10/03)
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- Scandium(III) trifluoromethanesulfonate-catalyzed Friedel-Crafts alkylation of aromatic compounds with secondary alcohol methanesulfonates
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Scandium(III) inflate was found to be an efficient catalyst for the Friedel-Crafts alkylation of aromatic compounds with methanesulfonates derived from secondary alcohols; the catalyst can be reused without a significant loss of activity.
- Kotsuki, Hiyoshizo,Oshisi, Takeshi,Inoue, Motoshi
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p. 255 - 256
(2007/10/03)
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- Zeolite as a reagent and as a catalyst: Reduction and isomerization of alkenes by Ca Y
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Depending on the number of Bronsted acid sites present, Ca Y can act either as a reagent and reduce stilbenes to 1,2-diarylethanes or act as a catalyst and isomerize cis-stilbenes to the more stable trans form; Lewis acid sites generated by the activation process yield radical cations from stilbenes but these do not yield any stable products.
- Pitchumani,Joy, Abraham,Prevost, Nicolette,Ramamurthy
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p. 127 - 128
(2007/10/03)
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- Unique carbon-carbon bond homolysis in 3-alkylcyclohexa-1,4-dienyl-3-carboxylic acid radicals
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3-Substituted cyclohexadienyl radicals generated by hydrogen abstraction from 3-alkylcyclohexa-1,4-diene-3-carboxylic acids readily fragment to produce alkyl radicals and benzoic acid; suitably functionalised alkyl groups cyclize in moderate yields.
- Baguley, Paul A.,Binmore, Gavin,Milne, Aynsley,Walton, John C.
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p. 2199 - 2200
(2007/10/03)
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- Synthesis of Certain Mesogenic Azomethines Derived from 4-Cycloalkylanilines and from 4-Cycloalkylbenzaldehydes
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General procedures are described for the synthesis of members of five pairs of related homologous series of mesogenic azomethines differing in the mode of linkage of the CH=N group and containing a cycloalkyl group in a terminal position.
- Byron, D. J.,Matharu, A. S.,Rees, M.,Wilson, R. C.
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p. 229 - 238
(2007/10/02)
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- Alkylation and Ring Formation by Electroreductive Coupling of Arylalkenes and Alkyl Mono- and Di-halides
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The electroreduction of a solution in N,N-dimethylformamide of an arylalkene and either an alkyl bromide or an alkane-α,ω-diyl dibromide in the presence of a sacrificial aluminium anode affords a monoalkylated or cyclic product, respectively.
- Leonel, Eric,Paugam, Jean Paul,Nedelec, Jean-Yves,Perichon, Jacques
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p. 278 - 279
(2007/10/03)
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- Poly-4-vinylpyridinium poly(hydrogen fluoride): A solid hydrogen fluoride equivalent reagent
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Poly-4-vinylpyridinium poly(hydrogen fluoride) (PVPHF), containing 35-60% hydrogen fluoride by weight, was prepared as a solid hydrogen fluoride equivalent reagent. PVPHF with 60% hydrogen fluoride by weight was found to be a versatile fluorinating agent for the hydrofluorination and bromofluorination of alkanes and alkynes, fluorination of alcohols as well as other fluorination reactions. Low hydrogen fluoride content PVPHF (3 equivalents of hydrogen fluoride to 1 equivalent of 4-vinylpyridine unit) was also found to be an efficient reagent for bromofluorination of alkenes in the presence of 1,3-dibromo-5,5-dimethylhydrantoin. Fluorosulfonic acid-modified PVPHF showed enhanced reactivities for the fluorination of secondary alcohols.
- Olah,Li,Wang,Surya Prakash
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p. 693 - 699
(2007/10/02)
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- Side Chain Hydroxylation of Aromatic Compounds by Fungi. Part 5. Exploring the Benzylic Hydroxylase of Mortierella isabellina
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The active site topography of the hydroxylase enzyme of Mortierella isabellina ATCC 42613, which carries out the benzylic hydroxylation of toluene, ethylbenzene, and related compounds, has been explored.Operating in a whole cell biotransformation mode, this enzyme shows selectivity in substrate processing based on the nature, position and size of substituent side chains close to the site of hydroxylation.The results of determination of the yield and stereochemistry of hydroxylation of over twenty substrates and potential substrates, together with previously reported data, have been used to propose an active site model for the benzylic hydroxylase enzyme.
- Holland, Herbert L.,Kindermann, Maik,Kumaresan, Sudalaiyandi,Stefanac, Tomislav
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p. 1353 - 1364
(2007/10/02)
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- Synthesis and evaluation of 4-alkylanilines as mammary tumor inhibiting aromatase inhibitors
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The 4-alkylanilines 1-20 were synthesized to elucidate the importance of the glutarimide moiety for the aromatase inhibiting activity of aminoglutethimide [3-(4-aminophenyl)-3-ethylpiperidine-2,6-dione, AG], the only non-steroidal aromatase inhibitor which is commercially available at present. The most interesting compounds were the (4-aminophenyl)cycloalkanes 4-6 (4, c-pentyl; 5, c-hexyl; 6, c-heptyl) and the 1-alkyl-1-(4-aminophenyl)cyclohexanes 1-3 (1, CH3; 2, C2H5; 3, n-C3H7). Derivatives 1-6 are stronger inhibitors of human placental aromatase than AG exhibiting relative potencies from 1.5 to 2.7 (AG≡1). For selectivity of action, the inhibition of desmolase (cholesterol side chain cleavage enzyme) was determined. Compounds 1-3 showed an inhibition comparable to AG, whereas compounds 4-6 exhibited no effect on desmolase. Being more potent and selective aromatase inhibitors in vitro, compounds 4-6, however, were not superior to AG in vivo, when the reduction of plasma estradiol concentration and the tumor inhibiting activity (PMSG-primed SD rats and DMBA-induced mammary carcinoma of the SD rat, postmenopausal model) were concerned.
- Hartmann,Batzl
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p. 537 - 544
(2007/10/02)
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- CH ACIDITY OF SUBSTITUTED CYCLOALKANES. V. THE KINETIC ISOTOPE EFFECT OF HYDROGEN EXCHANGE IN PHENYLCYCLOALKANES
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The kD/kT value for the isotope exchange of hydrogen in phenylcycloalkanes with cyclohexylamine (catalyzed by lithium cyclohexylamide) and with dimethyl sulfoxide decreases from 2.0 - 2.5 (for phenylcyclopentane and phenylcyclooctane) to 1.3 - 1.4 (for phenylcyclopropane).It was concluded that the reaction rate in the listed catalytic systems is controlled by the ionization of the CH acid.The relationships governing the variation of the kD/kT values in the ionization of phenylcycloalkanes are explained by the effect of structural rearrangement in the anionic fragments of the hydrocarbons on the mechanism of the elementary proton transfer event.
- Zharova, N. G.,Shapiro, O. I.
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p. 602 - 609
(2007/10/02)
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- Electrochemical Coupling of Activated Olefins and Alkyl Dihalides: Formation of Cyclic Compounds
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The electrochemical coupling of dimethyl maleate, methyl cinnamate, 4-phenyl-3-buten-2-one, or methyl acrylate with dibromomethane, 1,3-dibromopropane, 1,4-dibromobutane or other substituted alkyl dihalogenides gave satisfactory yields of cyclic products.The reactions were performed in an undivided cell fitted with a sacrificial aluminum anode, in N-methylpyrrolidone (NMP), at constant current, and at room temperature.The role of the anodically generated metallic ions in this cyclocondensation has been evidenced.
- Lu, Yu-Wei,Nedelec, Jean-Yves,Folest, Jean-Claude,Perichon, Jacques
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p. 2503 - 2507
(2007/10/02)
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- Properties of the Liquid Crystals Formed by Ceratin Azomethines Derived from 4-Cycloalkylanilines and from 4-Cycloalkylbenzaldehydes
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The liquid crystal behaviour of four homologous series of azomethines related to the nO.m series but containing a cycloalkyl group, is reported and discussed.Many of these compounds show extensive smectic polymorphism, one member of the nO.c6 series giving rise to five smectic polymorphic modofications for which phase type assignments have been made by thermal optical microscopy.Keywords: smectic polymorphism, azomethines, cycloalkyl derivatives
- Brown, J. W.,Byron, D. J.,Southcott, M.,Wilson, R. C.,Guillon, D.,et al.
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- Reductive Arylation of Vinyl Trifluoromethanesulfonates by Friedel-Crafts Reaction
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The reaction of vinyl triflates 1 with benzene and toluene in the presence of aluminium trichloride gives alkyl-, alkenyl-, and 1,1-diarylalkanes 5, 6, 3, 9 depending on the structure of the substrate used.A mechanism for the reductive arylation is proposed.
- Martinez, A. Garcia,Alvarez, R. Martinez,Fraile, A. Garcia,Hanack, Michael,Subramanian, L. R.
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p. 1255 - 1256
(2007/10/02)
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