- Easy preparation of 1,3-di-tert-butylbenzene and some derivatives thereof
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1,3-Di-tert-butylbenzene (4) can conveniently be prepared from 1-bromo-3,5-di-tert-butylbenzene (2) which, in turn, is obtained from the easily available 1,3,5-tri-tert-butylbenzene (1). The use of 4 is illustrated by the preparation of the arylphosphines 6 and 7.
- Komen, Corine M.D.,Bickelhaupt, Friedrich
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Read Online
- Interconversion equilibria between tert-butylbenzenes and tert-butyltoluenes
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The equilibrium of six positional isomerization reactions in the systems of sterically unhindered tert-butylbenzenes (TBB) and tert-butyltoluenes (TBT) was experimentally studied in the liquid phase over a wide temperature range. The thermodynamic charact
- Nesterov,Nesterova,Vodenkova,Naumkin,Repkin
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Read Online
- Exploiting the radical reactivity of diazaphosphinanes in hydrodehalogenations and cascade cyclizations
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The remarkable reducibility of diazaphosphinanes has been extensively applied in various hydrogenations, based on and yet limited by their well-known hydridic reactivity. Here we exploited their unprecedented radical reactivity to implement hydrodehalogenations and cascade cyclizations originally inaccessible by hydride transfer. These reactions feature a broad substrate scope, high efficiency and simplicity of manipulation. Mechanistic studies suggested a radical chain process in which a phosphinyl radical is generated in a catalytic cycle via hydrogen-atom transfer from diazaphosphinanes. The radical reactivity of diazaphosphinanes disclosed here differs from their well-established hydridic reactivity, and hence, opens a new avenue for diazaphosphinane applications in organic syntheses.
- Cheng, Jin-Pei,Yang, Jin-Dong,Zhang, Jingjing
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p. 4786 - 4790
(2020/06/18)
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- Radical Hydrodehalogenation of Aryl Bromides and Chlorides with Sodium Hydride and 1,4-Dioxane
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A practical method for radical chain reduction of various aryl bromides and chlorides is introduced. The thermal process uses NaH and 1,4-dioxane as reagents and 1,10-phenanthroline as an initiator. Hydrodehalogenation can be combined with typical cyclization reactions, proving the nature of the radical mechanism. These chain reactions proceed by electron catalysis. DFT calculations and mechanistic studies support the suggested mechanism.
- Hokamp, Tobias,Dewanji, Abhishek,Lübbesmeyer, Maximilian,Mück-Lichtenfeld, Christian,Würthwein, Ernst-Ulrich,Studer, Armido
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supporting information
p. 13275 - 13278
(2017/10/09)
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- Compositions for Treatment of Cystic Fibrosis and Other Chronic Diseases
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The present invention relates to pharmaceutical compositions comprising an inhibitor of epithelial sodium channel activity in combination with at least one ABC Transporter modulator compound of Formula A, Formula B, Formula C, or Formula D. The invention also relates to pharmaceutical formulations thereof, and to methods of using such compositions in the treatment of CFTR mediated diseases, particularly cystic fibrosis using the pharmaceutical combination compositions.
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Paragraph 0703
(2015/09/22)
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- Highly syn selective addition of aqueous HBr to hydrophobically shielded arylalkynes
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Hydrophobically shielded alkynes HCC-aryl, carrying 2,6-di- and 2,4,6-tri-tert-butylphenyl as the aryl group, can add aqueous HBr on heating in moist chloroform solutions to produce pure H2CC(-Br)-aryl (isolated yields 96%, no hydrolysis). Employment of DCC-aryl furnished initially only the E stereoisomer of DHCC(-Br)-aryl (stereospecific syn addition), which was slowly both dedeuteriated and partially transformed to the Z stereoisomer by HBr. The strongly retarded HBr addition to H3C-CC-aryl in moist chloroform produced again more E than Z product, whereas a thermodynamic E/Z ratio of 10:87 was found in moist acetic acid. Substitution of Br by LiSnMe3produced H2CC(-SnMe3)-aryl with well resolved long range 119Sn NMR coupling constants.
- Knorr, Rudolf,Rossmann, Eva C.,Knittl, Monika,B?hrer, Petra
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supporting information
p. 5332 - 5338
(2014/12/10)
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- Nickel-catalyzed hydrodehalogenation of aryl halides
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In the present study, the nickel-catalyzed dehalogenation of aryl and alkyl halides with iso-propyl zinc bromide or tert-butylmagnesium chloride has been examined in detail. With a straightforward nickel complex as pre-catalyst good to excellent yields and chemoselectivities were feasible for a variety of aryl and alkyl halides.
- Weidauer, Maik,Irran, Elisabeth,Someya, Chika I.,Haberberger, Michael,Enthaler, Stephan
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supporting information
p. 53 - 59
(2013/08/25)
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- Carbon-based leaving group in substitution reactions: Functionalization of sp3-hybridized quaternary and tertiary benzylic carbon centers
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Lewis acid promoted substitution reactions employing Meldrum's acid and 5-methyl Meldrum's acid as carbon-based leaving groups are described which transform unstrained quaternary and tertiary benzylic Csp 3-Csp3 bonds into Csp3-X bonds (X = C, H, N). Importantly, this reaction has a broad scope in terms of both suitable substrates and nucleophiles with good to excellent yields obtained (typically >90%).
- Mahoney, Stuart J.,Lou, Tiantong,Bondarenko, Ganna,Fillion, Eric
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p. 3474 - 3477
(2012/09/05)
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- Silylium-arene adducts: An experimental and theoretical study
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The solvent-coordinated [Me3Si·arene][B(C 6F5)4] salts (arene = benzene, toluene, ethylbenzene, n-propylbenzene, isopropylbenzene, o-xylene, m-xylene, p-xylene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene) are prepared and fully characterized. As an interesting decomposition product the formation of bissilylated fluoronium ion [Me3Si-F-SiMe 3]+ was observed and even cocrystallized with [Me 3Si·arene][B(C6F5)4] (arene = benzene and toluene). Investigation of the degradation of [Me 3Si·arene][B(C6F5)4] reveals the formation of fluoronium salt [Me3Si-F-SiMe3][B(C 6F5)4], B(C6F5) 3, and a reactive "C6F4" species which could be trapped with CS2. Upon addition of CS2, the formation of a formal S-heterocyclic carbene adduct, C6F 4CS2-B(C6F5)3, was observed. The structure and bonding of substituted [Me3Si· arene][B(C6F5)4] with arene = R nC6H6-n (R = H, Me, Et, Pr, and Bu; n = 0-6) is discussed on the basis of experimental and theoretical data. X-ray data of [Me3Si·arene][B(C6F5)4] salts reveal nonplanar arene species with significant cation...anion interactions. As shown by different theoretical approaches (charge transfer, partial charges, trimethylsilyl affinity values) stabilizing inductive effects occur; however, the magnitude of such effects differs depending on the degree of substitution and the substitution pattern.
- Ibad, Muhammad Farooq,Langer, Peter,Schulz, Axel,Villinger, Alexander
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supporting information; experimental part
p. 21016 - 21027
(2012/03/07)
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- METHOD FOR PRODUCING AROMATIC COMPOUND
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The present invention is a method for producing an aromatic compound by substituting the sulfonic acid group in a sulfonic acid aromatic-ester with a hydrogen atom in the presence of a platinum group metal catalyst, wherein an alkali metal carboxylate and
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Page/Page column 6
(2011/10/10)
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- Easier preparation of 2,6-Di-tert-butylphenyl derivatives 1
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Despite steric shielding by the 2,6-di-tert-butylphenyl group (super-2,6-xylyl=xyl*), inexpensive sodium phenolate (xyl*-ONa) reacts with dimethyl sulfate to produce only xyl*-OCH3 (94%) with complete suppression of the alternative 4-methylation. Reductive cleavage of xyl*-OCH3 by elemental lithium with the help of an electron carrier generates xyl*-Li, which in turn yields xyl*-CO2H (63%). The corresponding 4-methyl-derivatives of these compounds were obtained analogously. The acid chloride xyl*-COCl (77% yield) acylates HalMgCH 2R to give only xyl*-COCH3 (86%) or xyl*-COEt (97%). These two ketones react with n-butyllithium (no carbonyl addition) and Cl-PO(OEt)2 to furnish only the enol phosphates xyl*-C(=CH 2)OPO(OEt)2 (84%) or xyl*-C(=CHCH 3)OPO(OEt)2 (up to 70%), respectively. Only 1,2-elimination occurs when the latter two products are treated with tert-butyllithium, affording xyl*-CCH (68%) or xyl*-CCMe (88%), respectively. Georg Thieme Verlag Stuttgart - New York.
- Knorr, Rudolf,Rossmann, Eva Christine,Knittl, Monika
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scheme or table
p. 2124 - 2128
(2010/09/04)
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- Combining Homogeneous Catalysis with Heterogeneous Separation using Tunable Solvent Systems
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Tunable solvent systems couple homogeneous catalytic reactions to heterogeneous separations, thereby combining multiple unit operations into a single step and subsequently reducing waste generation and improving process economics. In addition, tunable solvents can require less energy than traditional separations, such as distillation. We extend the impact of such solvents by reporting on the application of two previously described carbon dioxide tunable solvent systems: polyethylene glycol (PEG)/organic tunable solvents (POTS) and organic/aqueous tunable solvents (OATS). In particular, we studied: (1) the palladium catalyzed carbon-oxygen coupling of 1-bromo-3,5-dimethylbenzene and o-cresol to potassium hydroxide to produce o-tolyl-3,5-xylyl ether and 1-bromo-3,5-di-tert-butylbenzene to potassium hydroxide to produce 3,5-di-tert-butylphenol in PEG400/1,4-dioxane/water and (2) the rhodium-catalyzed hydroformylation of p-methylstyrene in water/ acetonitrile to form 2-(p-tolyl) propanal. In addition, we introduce a novel tunable solvent system based on a modified OATS where propane replaces carbon dioxide. This represents the first use of propane in a tunable solvent system.
- Blasucci, Vittoria M.,Husain, Zainul A.,Fadhel, Ali Z.,Donaldson, Megan E.,Vyhmeister, Eduardo,Pollet, Pamela,Liotta, Charles L.,Eckert, Charles A.
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experimental part
p. 3932 - 3938
(2010/08/04)
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- Determination of critical temperatures for mixtures of alkylbenzenes
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The liquid-vapor critical temperatures of benzene mixtures with 1,3-di-tert-butylbenzene, 1,4-di-tert-butylbenzene, and 1,3,5-tri-tert- butylbenzene; a mixture of di-tert-butylbenzene isomers; and a toluene mixture with 3,5-di-tert-butyltoluene were determined over the entire range of composition by means of the amouule method. It was found that the excess critical temperature of the mixtures is related to the critical volumes of the substances. The capabilities of several calculation methods for predicting the critical temperature of mixtures were analyzed on the basis of published data and the obtained results. The Lee-Kesler rules of mixtures were refined by introducing binary interaction parameters.
- Nesterov,Nazmutdinov,Sarkisova,Nesterova,Vodenkova
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p. 434 - 441
(2008/09/16)
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- Radical aromatic substitution with benzene chromiumtricarbonyl
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Radical aromatic substitution of tert-butyl groups for hydrogen on simple arene chromiumtricarbonyl complexes was accomplished. Preexisting tert-butyl groups and methoxy groups directed incoming radicals primarily to the meta-position, and methoxy groups diminished the rate of substitution by roughly tenfold.
- Byers, Jeffrey H.,Neale, Nathan R.,Bradford Alexander,Gangemi, Stephen P.
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p. 7903 - 7905
(2008/03/27)
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- Thermolysis of free-radical initiators: tert-butylazocumene and its 1,3- and 1,4-bisazo and 1,3,5-trisazo analogues
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Four tert-butylazocumenes (4-7) were prepared from the corresponding cyanobenzenes, and their nitrogen evolution kinetics and products were analyzed. In combination with TEMPO, the simplest compound, tert-butylazocumene (4), shows promise as a "one-radical" initiator of styrene polymerization. The ABNO-trapped cumyl radical 29 is a particularly stable trialkylhydroxylamine, whose thermolysis half-life is 2.1 h at 150 °C. Taking advantage of this stability, we trapped the cumyl radical centers from 7 to afford tris adduct 32a. While the behavior of the meta bisazoalkane 6 can be mostly predicted from that of 4, the para isomer 5 exhibits both unusual products and kinetics, attributed to the formation of quinodimethane 33 via azo-containing radical 34. In fact, flash vacuum pyrolysis of 5 allowed observation of the 1H and 13C NMR spectra of 33, whose persistence even at ambient temperature showed that this quinodimethane is far more stable than the parent 36. Finally, evidence is presented that 7 is an initiator of star polymerization.
- Engel,Pan,Ying,Alemany
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p. 3706 - 3715
(2007/10/03)
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- Thermal behavior of Spiroozonides from formaldehyde-O-oxide and tropone derivatives: A coarctate reaction
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Spiroozonides of tropones undergo an unusually facile fragmentation via the coarctate Mobius transition state 1. The ozonides are generated from formaldehyde O-oxide and tropone derivatives at -90°C. Depending on the substitution, they fragment at temperatures between -60 to +50°C to give carbon dioxide, formaldehyde, and benzene derivatives.
- Berger, Christian,Dieterich, Stefan,Dilger, Ulrich,Geuenich, Daniel,Helios, Heike,Herges, Rainer,Kirchmer, Peter,Roettele, Herbert,Schroeder, Gerhard
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p. 1854 - 1857
(2007/10/03)
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- Formation of Persistent Benzyl Radicals by Protonation of the Radical Anions of Sterically Hindered Dithiobenzoic Esters
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ESR signals due to a second species are observed besides the spectra of the corresponding radical anions when the methyl ortho-(tert-butyl)dithiobenzoates 1, 4, and 6 are electroreduced in situ in dimethylformamide.It is shown by investigation of model co
- Edler, Ronald,Voss, Juergen
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p. 187 - 192
(2007/10/02)
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- Isomerization and Aromatization of the 1,3-Di-tert-butylcyclohexadienes in Strongly Basic Media
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The five isomeric 1,3-di-tert-butylcyclohexadienes are equilibrated in t-BuOK/Me2SO at 30-55 deg C.In lithium ethylamide in ethylamine at 0 deg C, equilibration is accomplished within the set of three dienes which possess a tertiary hydrogen or between the other two dienes; however, one set is not transformed to the other.Aromatization accompanies the equilibration of the set of three but not the set of two.With a large excess of KAPA, the diene is transformed rapidly to the salt which aromatizes.With an excess of diene, the interconversion of all of the dienes accompanies aromatization (intraset isomerization being faster than interset interchange).In KAPA at 0 deg C, the introduction of dicyclohexyl-18-crown-6 inhibits aromatization; however, after a time reaction slows although the basicity of the solution remains strong enough to abstract a proton from a tertiary carbon.The effect of the base system upon the competitive reactions of cyclohexadienyl carbanions is understood in terms of the differing interactions of the carbanionic salts with the medium.
- Venkatasubramanian, N.,Hawkins, Adrian,Siegel, Samuel
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p. 1222 - 1226
(2007/10/02)
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- Photochemical Bromination of Simple Arenes
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Photochemical bromination of benzene, fluorobenzene, chlorobenzene, t-butylbenzene, α,α,α-trifluorotoluene, and (in tetrachloromethane) biphenyl and naphthalene gives substitution products and adducts such as 1,2,3,4,5,6-hexabromocyclohexane (1).The decomposition of (1) and of the analogous chlorobenzene adduct (3) under photochemical conditions gives the parent arene, the monobrominated halogenobenzene, and bromine which may be scavenged by toluene to give benzyl bromide or by benzene to give bromobenzene and dibromobenzenes.Addition is a kinetically controlled process, so that the mechanism of formation of these aryl bromides must be largely through the reversible formation of these adducts.This is consistent with the unusual orientation of apparent attack by bromine upon the arene substrates, since the relative amounts of the isomeric aryl bromides is a consequence of the relative stabilities and ease of elimination of HBr and Br2 from a family of adducts. The range of isomer distribution found within the reaction of each arene with bromine is consistent with two competing processes involved in the formation of the aryl bromides; one of these might by the direct homolytic substitution by bromine atoms upon the arene.
- Bolton, Roger,Bhangar, Muhammad Iqbal,Williams, Gareth H.
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p. 893 - 896
(2007/10/02)
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- The Equilibria in the Interconversions of t-Butylbenzenes
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The equilibra in the isomerisation and transalkylation of liquid t-butylbenzenes have been investigated in the temperature range 273 - 373 K.The thermodynamic characteristics of the rections have been determined and the enthalpies of formation (in the liquid state) of di- and tri-t-butylbenzenes have been calculated from the experimental and literature data.
- Nesterova, T. N.,Verevkin, S. P.,Karaseva, S. Ya.,Rozhnov, A. M.,Tsvetkov, V. F.
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p. 297 - 298
(2007/10/02)
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- Dienes as Possible Intermediates in the Catalytic Hydrogenation of Aromatic Hydrocarbons. 2. Dienes Derived from 1,3-Di-tert-butylbenzene and a Rhodium Catalyst
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The evolution of the products from the catalytic hydrogenation (Rh/Al2O3) of the five isomeric diene derivatives of 1,3-di-tert-butylbenzene (9) is compared with the formation of the observable cyclohexene intermediates and the saturated products from the
- Cozort, James Ray,Outlaw, James F.,Hawkins, Adrian,Siegel, Samuel
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p. 4190 - 4197
(2007/10/02)
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- THE REACTION OF A PHOSPHAALKENE WITH ORTHOQUINONES
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The reaction of (2,6-dimethylphenyl)diphenylmethylenephosphine (1) with tetrachloro-o-benzoquinone (2), 3,5-di-t-butyl-o-benzoquinone (3) and phenanthrenequinone (4) yielded the formal cycloaddition products 5,14 and 19, respectively.In the given or
- Knaap, Th. A. van der,Bickelhaupt, F.
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p. 3189 - 3196
(2007/10/02)
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- Derivatives of m-di-tert-butylbenzene. Part VII. 1H Nuclear magnetic resonance spectra of some sterically crowded halogenated aromatic compounds
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The 1H NMR spectra of seven series of halogenated derivatives of m-di-tert-butylbenzene have been analysed.The results show that the hydrogen atom between the tert-butyl groups is screened from the magnetic influence of the halogen atoms.The results also
- Koning, Adrianus Jan de
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p. 385 - 389
(2007/10/02)
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- Synthesis of 4-tert-Butyl-1,1-dimethylindan and 7-tert-Butyl-3,3-dimethyl-1-indanone and a Comparison of Isomers
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4-tert-Butyl-1,1-dimethylindan was synthesized to help establish the identity of products (5- and 6-tert-butyl-1,1-dimethylindan as minor and major products, respectively) from the sulfuric acid catalyzed condensation of tert-butylbenzene and isoprene.NMR (1H and 13C) studies of these hydrocarbons and their corresponding indanones, obtained through chromic acid oxidation, provided structural proof.Gated decoupling experiments were crucial to complete assignment.
- Eisenbraun, Edmund J.,Harms, Weldon M.,Palaniswamy, Venkatapuram A.,Chen, Hoffman H.,Porcaro, Peter J.,et al.
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p. 342 - 346
(2007/10/02)
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- Picosecond Laser Photolysis Studies of Hydrogen Atom Transfer Reaction via Heteroexcimer State in Pyrene-Primary and Pirene-Secondary Aromatic Amine Systems: Role of "Hydrogen-Bonding" Interaction between Amino Group of Donor and ? Electron Acceptor in the Heteroexcimer
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The mechanism of charge transfer followed by proton transfer in the hydrogen atom transfer reaction of excited pyrene-primary and -secondary amine systems has been directly demonstrated by means of a picosecond laser photolysis method.In the case of pyrene-N-ethylamine heteroexcimer system in hexane, for example, it has been observed that the 1-hydro-1-pyrenyl radical and the pyrene triplet state are produced simultaneously in the time region of subnanosecond to nanosecond.The deuteration of the NH group of the amine affects considerably the rate of formation of the 1-hydro-1-pyrenyl radical but not the rate of intersystem crossing from the heteroexcimer.On the basis of the results obtained for various pyrene-primary and -secondary aromatic amine heteroexcimer systems, the nature of the interaction between donor and acceptor in these heteroexcimers and their conformation in relation to the mechanism of the hydrogen atom transfer reaction via heteroexcimer have been elucidated.
- Okada, Tadashi,Karaki, Ichiro,Mataga, Noboru
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p. 7191 - 7195
(2007/10/02)
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