- Aryllithiums with increasing steric crowding and lipophilicity prepared from chlorides in diethyl ether. the first directly prepared room-temperature-stable dilithioarenes
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A convenient procedure has been developed for the preparation of synthetically useful, room-temperature-stable aryllithiums starting from aryl chlorides and lithium metal. The method provides a route to aryllithiums which have previously not been accessible cleanly or could only be prepared by using more expensive starting materials.
- Screttas, Constantinos G.,Steele, Barry R.,Micha-Screttas, Maria,Heropoulos, Georgios A.
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supporting information
p. 5680 - 5683
(2013/01/15)
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- Regioselective synthesis of alkylarenes by two-step ipso-substitution of aromatic dicarboxylic acids
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A strategy for the regioselective alkylation of arenes was developed, starting from commercially available and inexpensive terephthalic acid or naphthalene-1,4-dicarboxylic acid. The method entails a formal ipso-substitution of the carboxylate groups by a sequence of reductive alkylation under Birch conditions and subsequent acid-mediated rearomatization with loss of carbon monoxide and carbon dioxide. More than 20 different arenes with various side-chains were synthesized. With naphthalene-1,4-dicarboxylic acid as starting material, we were able to control the degree of alkylation by choosing the appropriate electrophile in the Birch reduction. Thus, bisalkylated naphthalenes and naphthoic acids became available chemoselectively. All reactions afforded a single regioisomer exclusively in high yields. Overall, aromatic dicarboxylic acids are suitable substrates for a two-step ipso-substitution that allows the selective synthesis of alkylated benzenes and naphthalenes.
- Bramborg, Andrea,Linker, Torsten
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p. 5552 - 5563
(2012/11/07)
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- Direct carboxylation of arenes and halobenzenes with CO2 by the combined use of AlBr3 and R3SiCl
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The Lewis acid-mediated direct carboxylation of aromatic compounds with CO2 is efficiently promoted by the addition of silyl chlorides bearing three alkyl and/or aryl substituents in total on the silicon atom. Thus, toluene, xylenes, mesitylene, and some other alkylbenzenes are treated with a 1:1 mixture of AlBr3 and Ph3SiCl in neat substrates under CO2 pressure (3.0 MPa) at room temperature, to give the corresponding carboxylic acids in 60-97% yields, based on AlBr3. Polycyclic arenes, including naphthalene, phenanthrene, and biphenyl, are regioselectively carboxylated in 91-98% yields with the aid of 1 molar equiv of AlBr3 and Ph3SiCl in an appropriate solvent, chosen from benzene, chlorobenzene, and fluorobenzene. These solvents, as well as bromobenzene, resist carboxylation; however, they are also carboxylated in moderate yields when treated with a 1:5 mixture of AlBr3 and iPrSiCl at elevated temperatures. The FT-IR spectrum of a mixture prepared by exposing a suspension of AlBr3 and Ph3SiCl in cyclohexane to CO 2 exhibits an absorption band around 1650 cm-1, assigned to the C=O stretching vibration of a species consisting of CO2, AlBr3, and Ph3SiCl, which suggests that the silyl chlorides activate CO2 in cooperation with AlBr3. 1H NMR analysis of unworked-up reaction mixtures reveals that the products merge as aluminum carboxylates. The mass balance concerning silicon indicates that the silyl chlorides are recycled during the reaction sequence. On the basis of these observations, a feasible mechanism is proposed for the present carboxylation.
- Nemoto, Koji,Yoshida, Hiroki,Egusa, Naoki,Morohashi, Naoya,Hattori, Tetsutaro
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experimental part
p. 7855 - 7862
(2011/02/21)
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- HYDROXYCARBONYLATION OF ARYL AND VINYL BROMIDES
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Process for the preparation of aryl or vinyl carboxylic acids via Pd-catalysed hydroxycarbonylation of aryl and vinyl bromides, wherein the aryl or vinyl bromides are reacted with a carbon monoxide source comprising lithium formate and acetic acid anhydride, in the presence of the combination of palladium complexes with the chelating ligand dppf (1,1-bis[diphenylphosphino]ferrocene).
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Page/Page column 10; 12; 13; 15
(2008/06/13)
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- Palladium-catalyzed hydroxycarbonylation of aryl and vinyl bromides by mixed acetic formic anhydride
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The palladium-catalyzed hydroxycarbonylation of aryl and vinyl bromides in the presence of acetic anhydride and lithium formate as a carbon monoxide source has been developed. The combination of palladium(II) acetate with 1,1′-bis(diphenylphosphino)ferrocene (dppf) is an efficient catalytic system when the reaction is carried out at 120 °C. Georg Thieme Verlag Stuttgart.
- Berger, Philippe,Bessmernykh, Alla,Caille, Jean-Claude,Mignonac, Sylviane
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p. 3106 - 3110
(2008/02/10)
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- SnCl4-mediated oxidative biaryl coupling reaction of 1-naphthol and subsequent ring closure of 2,2′-binaphthol to the dinaphthofuran framework
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A simple method for the direct synthesis of 2,2′-binaphthols 2 and dinaphtho[1,2-b;2′,1′-d]furans 3 under mild conditions was developed, utilizing a biaryl coupling reaction via electron donor-acceptor complexes of 1-naphthols with SnCl4. Heating of the complex in a sealed tube for (18-24 h) afforded the corresponding o-o coupled product 2 in excellent yield. Prolonged reaction (56-65 h) under the same conditions afforded 3 in high yield in one step. We also found that in the case of α-naphthol without substituents other than a hydroxyl group at the C-1 position, regioselective o-o coupling reaction proceeded. The products 2a, 2b and 2g should be useful as synthetic intermediates for naturally occurring 3,3′-bijuglone, 3,3′-biplumbagin and elliptinone.
- Takeya, Tetsuya,Doi, Hirohisa,Ogata, Tokutaro,Otsuka, Tsuyoshi,Okamoto, Iwao,Kotani, Eiichi
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p. 6295 - 6310
(2007/10/03)
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- Lewis acid-mediated carboxylation of fused aromatic compounds with carbon dioxide
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Direct and regioselective carboxylation of fused aromatic compounds with carbon dioxide is achieved with the aid of a Lewis acid. Thus, treatment of naphthalene, anthracene, and phenanthrene with carbon dioxide (3.0 MPa) in benzene at 40 °C in the presenc
- Suzuki, Yutaka,Hattori, Tetsutaro,Okuzawa, Tomohiro,Miyano, Sotaro
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p. 102 - 103
(2007/10/03)
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- Dissociation of naphthoic acids in non-aqueous media. Comparison of benzene and naphthalene skeletons
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Seven monosubstituted 1-naphthoic acids were synthesized by new or modified procedures, and their dissociation constants were measured potentiometrically at 25 °C in methanol, acetonitrile, dimethylformamide, and pyridine. Dissociation constants of these along with thirteen substituted 1-naphthoic acids and twenty-five substituted 2-naphthoic acids previously studied were measured at 25 °C in ethanol and dimethyl sulfoxide. The pKHA values of 3-and 4-substituted 1-naphthoic acids were treated by simple linear regression and principal component analysis, and the results were used for comparison of model compounds and of corresponding 3-and 4-substituted benzoic acids with the aim of comparison of benzene and naphthalene skeletons. It has been found, the 3 and 4 positions of the 1-naphthyl system can roughly be compared with the meta and para positions of benzene, respectively.
- Parik, Patrik,Wolfova, Jitka,Ludwig, Miroslav
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p. 385 - 394
(2007/10/03)
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- Photochemistry of substituted 1-naphthylmethyl esters of phenylacetic and 3-phenylpropanoic acid: Radical pairs, ion pairs, and marcus electron transfer
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The ring-subtituted 1-naphthylmethyl esters of phenylacetic (3a-k) and 3-phenylpropanoic (5a-c) acid have been photolyzed in methanol solvent. The major products of these reactions are derived from two critical intermediates, the 1-naphthylmethyl radical/acyloxy radical pair and the 1-naphthylmethyl cation/carboxylate anion ion pair. The radical pair results in formation of the in-cage coupled products 8a-k and 10a-c after loss of carbon dioxide from the acyloxy radical. The ion pair leads to the methyl ethers 6a-k and the carboxylic acids 7 and 9. The competition between the radical and ionic pathways is very dependent upon the substituents on the naphthalene ring. Analysis of these substituent effects results in a proposed mechanism of initial homolytic cleavage of the carbon-oxygen bond of the ester from the excited singlet state. This radical pair then partitions between two pathways: decarboxylation of the acyloxy radical and electron transfer converting the radical pair to the ion pair. The rates of electron transfer are shown to fit Marcus theory in both the normal and the inverted region.
- DeCosta, Dayal P.,Pincock, James A.
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p. 2180 - 2190
(2007/10/02)
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- ELECTRON TRANSFER ACTIVATION. HYDROPEROXIDE INTERMEDIATES IN A NOVEL AND SELECTIVE PROCEDURE FOR BENZYLIC OXIDATIONS.
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A selective and mild photochemical procedure for benzylic oxidations with 9,10-dicyanoanthracene (DCA) an usual electron acceptor, in the presence of methyl viologen (MV2+), an electron relay, has been developed.Methyl and methylene groups are oxidized in good to excellent yields to the corresponding hydroperoxides.
- Santamaria, J.,Jroundi, R.,Rigaudy, J.
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p. 4677 - 4680
(2007/10/02)
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- Manganese(III)-Mediated Formylation of Aromatic Compounds in the Presence of Malonic Acid
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The reaction of naphthlenes with malonic acid in the presence of manganese(III) acetate gives naphthalenecarbaldehydes and naphthalenecarboxylic acids.Similar reactions of anthracene, pyrene, and methoxybenzenes also yield formylated and carboxylated products.It was found that the formyl group introduced to the aromatic ring was not derived from carboxymethyl radical generated directly by the thermolysis of manganese(III) acetate, but from a dicarboxymethyl radical formed by the interaction of malonic acid and manganese(III) acetate.In addition, it was also found that the dicarboxymethyl radicals attacked the position of the highest electron density on the aromatic ring and that this formylation was effective when the ionization potential of the aromatic copound was lower than 7.8 eV.
- Nishino, Hiroshi,Tsunoda, Katsunori,Kurosawa, Kazu
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p. 545 - 550
(2007/10/02)
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- Synthesis and Properties of Dinitromethylated Arenes. Reinvestigation of the Ponzio Reaction
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Several title compounds have been prepared by the modified Ponzio procedure and their IR, 1 H and 13 C NMR data are presented.In some cases trinitromethylated arenes were obtained as a by-product.Oxidative cleavage to parent aldehydes and oxidation to carboxylic acids were the major competing reactions. 9-Anthracenecarbaldehyde oxime and 10-methyl-9-anthracenecarbaldehyde oxime reacted with nitrogen dioxide in an unexpected way, giving 10-nitro-9-anthracenecarbonitrile oxide and 10-methyl-10-nitro-9-anthrone as the respective main products.Nitration of (dinitromethyl)benzene has also been examined under various conditions.
- Suzuku, Hitomi,Takaoka, Hiroshi,Yamamoto, Hidetoshi,Ogawa, Takuji
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p. 2927 - 2932
(2007/10/02)
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- Exciplex and Radical Ion Intermediates in Electron-transfer Reactions: Solvent effect on the Photo-oxygenation of 1,4-Dimethylnaphthalene sensitized by 9,10-Dicyanoanthracene
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The 9,10-dicyanoanthracene-sensitized photo-oxygenation of 1,4-dimethylnaphthalene is shown to depend on solvent polarity.Radical ion pair and singlet exciplex are suggested to be intermediates in this photochemical reaction.Mechanisms consistent with the effects of solvent polarity are proposed.
- Bokobza, Liliane,Santamaria, Jean
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p. 269 - 272
(2007/10/02)
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- PHOTOOXYGENATIONS PAR TRANSFERT D'ELECTRON SENSIBILISEES PAR LE DICYANO-9,10 ANTHRACENE. ROLE DU SOLVANT ET FORMATION D'OXYGENE SINGULET.
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Photooxygenation of naphtalenic compounds sensitized by electron acceptors like 9,10 dicyanoanthracene (DCA) is shown to proceed by two distinct ways depending on the solvent polarity.In a polar solvent superoxide ion (O2-.) as well as singlet oxygen (1O2*) are involved while in a non polar solvent only singlet oxygen is produced.
- Santamaria, J.,Gabillet, P.,Bokobza, L.
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p. 2139 - 2142
(2007/10/02)
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- Preparation of a series of substituted fluoromethylnaphthalenes
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A series of 22 3- and 4-substituted 1-fluoromethylnaphthalenes have been synthesized.Details of practical procedures for the preparation of all intermediates are described, and physical properties for all of the substituted naphthalenes synthesized, and spectral parameters for 51 previously unknown compounds, are given.
- Dixon, Elisabeth A.,Fischer, Alfred,Robinson, Frank P.
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p. 2629 - 2641
(2007/10/02)
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- Kinetics of Base-catalysed Iodination of Substituted Acetonaphthones
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Kinetics of iodination of 6-substituted 2-acetonaphthones and of 4-substituted 1-acetonaphthones in 20percent pyridine-20percent methanol-60percent water (v/v) have been followed at three temperatures.The Hammett equation applies very well to these reactions.The rate constants for various heterocyclic base-catalysed iodination of acetophenone and of 1- and 2-acetonaphthones in 60percent (v/v) methanol-water solvent have been correlated with pKa values of the conjugate acids of the heterocyclic bases via the Broensted equation giving β values of 0.88, 1.01 and 0.92 for acetophenone, 1-acetonaphthone and 2-acetonaphthone respectively.The influence of solvent on the rates of pyridine-catalysed iodination of acetophenone and of 1- and 2-acetonaphthones has also been studied.
- Ananthakrishnanadar, P.,Gnanasekaran, C.
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p. 646 - 649
(2007/10/02)
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