- Synthesis of 1,4,5,16-tetrahydroxytetraphenylene
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This paper concerns the synthesis of 1,4,5,16-tetrahydroxytetraphenylene, which may function as a building block for the construction of molecular scaffolds. The synthesis of 1,4,5,16-tetrahydroxytetraphenylene was realized by stepwise Diels-Alder reactions to form two benzene rings using 1,10-dimethoxydibenzo[a,e]cyclooctene as a precursor. This key intermediate, in turn, could be obtained by photo-rearrangement of its corresponding barrelene.
- Hui, Chi Wai,Mak, Thomas C.W.,Wong, Henry N.C.
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- Atoms-in-molecules analysis of extended hypervalent five-center, six-electron (5c-6e) C2Z2O interactions at the 1,8,9-positions of anthraquinone and 9-methoxyanthracene systems
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To clarify the nature of five-center, six-electron (5c-6e) C 2Z2O interactions, atoms-in-molecules (AIM) analysis has been applied to an anthraquinone, 1,8-(MeZ)2ATQ (1 (Z = Se), 2 (Z = S), and 3 (Z = O)), and a 9-methoxyanthracene system, 9-MeO-1,8-(MeZ) 2ATC (4 (Z = Se), 5 (Z = S), and 6 (Z = O)), as well as 1-(MeZ)ATQ (7 (Z = Se), 8 (Z = S), and 9 (Z = O)) and 9-MeO-1-(MeZ)ATC (10 (Z = Se), 11 (Z = S), and 12 (Z = O)). The total electronic energy density (Hb(r c)) at the bond critical points (BCPs), an appropriate index for weak interactions, has been examined for 5c-6e C2Z2O and 3c-4e CZO interactions of the np(O)...σ*(Z-C) type in 1-12. Some hydrogen-bonded adducts were also re-examined for convenience of comparison. The total electronic energy densities varied in the following order: O...O (3: Hb(rc) = 0.0028 au) = O...O (6: 0.0028 au) > O...O (9: 0.0025 au) ≥ NN...HF (0.0024 au) ≥ O...O (12: 0.0023 au) ? H2O...HOH (0.0015 au) > S...O (8: 0.0013 au) = S...O (2: 0.0013 au) > S...O (11: 0.0012 au) = S...O (5: 0.0012 au) > HF...HF (0.0008 au) = Se...O (10: 0.0008 au) = Se...O (4: 0.0008 au) ≥ Se...O (1: 0.0007 au) ≥ Se...O (7: 0.0006 au) ? HCN...HF (-0.0013 au). Hb(rc) values for S...O were predicted to be smaller than the hydrogen bond of H2O...HOH and Hb(r c) values for Se...O are very close to or slightly smaller than that for HF...HF in both the ATQ and 9-MeOATC systems. In the case of Z = Se and S, Hb(rc) values for 5c-6e C2Z 2O interactions are essentially equal to those for 3c-4e CZO if Z is the same. The results demonstrate that two np(O) ...σ*(Z-C) 3c-4e interactions effectively connect through the central np(O) orbital to form the extended hypervalent 5c-6e system of the σ*(C-Z)-np(O)...σ* (Z-C) type for Z = Se and S in both systems. Natural bond orbital (NBO) analysis revealed that ns(O) also contributes to some extent. The electron charge densities at the BCPs, NBO analysis, and the total energies calculated for 1-12, together with the structural changes in the PhSe derivatives, support the above discussion.
- Nakanishi, Waro,Nakamoto, Takashi,Hayashi, Satoko,Sasamori, Takahiro,Tokitoh, Norihiro
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- Ionic Highways from Covalent Assembly in Highly Conducting and Stable Anion Exchange Membrane Fuel Cells
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A major challenge in the development of anion exchange membranes for fuel cells is the design and synthesis of highly stable (chemically and mechanically) conducting membranes. Membranes that can endure highly alkaline environments while rapidly transporting hydroxides are desired. Herein, we present a design using cross-linked polymer membranes containing ionic highways along charge-delocalized pyrazolium cations and homoconjugated triptycenes. These ionic highway membranes show improved performance. Specifically, a conductivity of 111.6 mS cm-1 at 80 °C was obtained with a low 7.9% water uptake and 0.91 mmol g-1 ion exchange capacity. In contrast to existing materials, ionic highways produce higher conductivities at reduced hydration and ionic exchange capacities. The membranes retain more than 75% of their initial conductivity after 30 days of an alkaline stability test. The formation of ionic highways for ion transport is confirmed by density functional theory and Monte Carlo studies. A single cell with platinum metal catalysts at 80 °C showed a high peak density of 0.73 W cm-2 (0.45 W cm-2 from a silver-based cathode) and stable performance throughout 400 h tests.
- Kim, Yoonseob,Wang, Yanming,France-Lanord, Arthur,Wang, Yichong,Wu, You-Chi Mason,Lin, Sibo,Li, Yifan,Grossman, Jeffrey C.,Swager, Timothy M.
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supporting information
p. 18152 - 18159
(2019/11/14)
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- Ionic Highways from Covalent Assembly in Highly Conducting and Stable Anion Exchange Membrane Fuel Cells
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A major challenge in the development of anion exchange membranes for fuel cells is the design and synthesis of highly stable (chemically and mechanically) conducting membranes. Membranes that can endure highly alkaline environments while rapidly transporting hydroxides are desired. Herein, we present a design using cross-linked polymer membranes containing ionic highways along charge-delocalized pyrazolium cations and homoconjugated triptycenes. These ionic highway membranes show improved performance. Specifically, a conductivity of 111.6 mS cm-1 at 80 °C was obtained with a low 7.9% water uptake and 0.91 mmol g-1 ion exchange capacity. In contrast to existing materials, ionic highways produce higher conductivities at reduced hydration and ionic exchange capacities. The membranes retain more than 75% of their initial conductivity after 30 days of an alkaline stability test. The formation of ionic highways for ion transport is confirmed by density functional theory and Monte Carlo studies. A single cell with platinum metal catalysts at 80 °C showed a high peak density of 0.73 W cm-2 (0.45 W cm-2 from a silver-based cathode) and stable performance throughout 400 h tests.
- Kim, Yoonseob,Wang, Yanming,France-Lanord, Arthur,Wang, Yichong,Wu, You-Chi Mason,Lin, Sibo,Li, Yifan,Grossman, Jeffrey C.,Swager, Timothy M.
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supporting information
p. 18152 - 18159
(2019/11/28)
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- A practical synthesis of 1,4,5,8-tetramethoxyanthracene from inexpensive and readily available 1,8-dihydroxyanthraquinone
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The preparation of gram quantities of 1,4,5,8-tetra-methoxyanthracene from commercially available and inexpensive 1,8-dihydroxyanthraquinone is described. The key steps in the synthesis involve bromination of 1,8-dimethoxyanthracene to form 1,8-dibromo-4,5-dimethoxyanthracene followed by Cu(I) catalyzed replacement of bromo substituents with methoxy groups. The contrasting reports concerning the preparation of 1,8-dimethoxy-anthracene from 1,8- dimethoxyanthraquinone using zinc dust in refluxing acetic acid are also discussed. Georg Thieme Verlag Stuttgart · New York.
- Navale, Tushar S.,Rathore, Rajendra
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experimental part
p. 805 - 809
(2012/04/10)
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- Design and synthesis of a novel triptycene-based ligand for modeling carboxylate-bridged diiron enzyme active sites
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A novel triptycene-based ligand with a preorganized framework was designed to model carboxylate-bridged diiron active sites in bacterial multicomponent monooxygenase (BMM) hydroxylase enzymes. The synthesis of the bis(benzoxazole)-appended ligand L1 depicted was accomplished in 11 steps. Reaction of L1 with iron(II) triflate and a carboxylate source afforded the desired diiron(II) complex [Fe2L1(μ-OH)-(μ-O 2CArTol)(OTf)2].
- Li, Yang,Cao, Rui,Lippard, Stephen J.
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p. 5052 - 5055
(2011/12/02)
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- Synthesis, antiprolife ativeactivity and inhibition of tubulinpolymerization byanthracenone-based oxime derivatives
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A series of anthracenone-based oxime ethers and-esters were synthesized in order to evaluate their antiproliferative activity. Several investigated compounds displayed strong antiproliferative activity against K562 leukemia cells and proved to be strong inhibitors of tubulin polymerization. In this context,anthracenone-based oxime ethers and-esters are considered to contribute to the development of novel antiproliferative drugs,based on tubulin interaction.
- Surkau, Georg,B?hm, Konrad J.,Müller, Klaus,Prinz, Helge
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scheme or table
p. 3354 - 3364
(2010/08/06)
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- Syntheses and structures of hypervalent pentacoordinate carbon and boron compounds bearing an anthracene skeleton - Elucidation of hypervalent interaction based on X-ray analysis and DFT calculation
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Pentacoordinate and tetracoordinate carbon and boron compounds (27, 38, 50-52, 56-61) bearing an anthracene skeleton with two oxygen or nitrogen atoms at the 1,8-positions were synthesized by the use of four newly synthesized tridentate ligand precursors. Several carbon and boron compounds were characterized by X-ray crystallographic analysis, showing that compounds 27, 56-59 bearing an oxygen-donating anthracene skeleton had a trigonal bipyramidal (TBP) pentacoordinate structure with relatively long apical distances (ca. 2.38-2.46 A). Despite the relatively long apical distances, DFT calculation of carbon species 27 and boron species 56 and experimental accurate X-ray electron density distribution analysis of 56 supported the existence of the apical hypervalent bond even though the nature of the hypervalent interaction between the central carbon (or boron) and the donating oxygen atom was relatively weak and ionic. On the other hand, X-ray analysis of compounds 50-52 bearing a nitrogen-donating anthracene skeleton showed unsymmetrical tetracoordinate carbon or boron atom with coordination by only one of the two nitrogen-donating groups. It is interesting to note that, with an oxygen-donating skeleton, the compound 61 having two chlorine atoms on the central boron atom showed a tetracoordinate structure, although the corresponding compound 60 with two fluorine atoms showed a pentacoordinate structure. The B-O distances (av 2.29 A) in 60 were relatively short in comparison with those (av 2.44 A) in 59 having two methoxy groups on the central boron atom, indicating that the B-O interaction became stronger due to the electron-withdrawing nature of the fluorine atoms.
- Yamashita, Makoto,Yamamoto, Yohsuke,Akiba, Kin-Ya,Hashizume, Daisuke,Iwasaki, Fujiko,Takagi, Nozomi,Nagase, Shigeru
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p. 4354 - 4371
(2007/10/03)
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- Methylation of 1,8-dihydroxy-9,10-anthraquinone with and without use of solvent-free technique
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A convenient and environmentally friendly solvent-free procedure has been developed for dimethylation of 1,8-dihydroxy-9,10-anthraquinone with excellent yield. A highly selective monomethylation of 1,8-dihydroxy-9,10-anthraquinone in refluxing tetraglyme makes monomethylated peri-dihydroxy-9,10-anthraquinones easily available. Alternatively, irradiation in a domestic microwave oven has been employed for the solvent-free monomethylation of 1,8-dihydroxy-9,10-anthraquinone.
- Sereda, Grigoriy A.,Akhvlediani, David G.
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p. 9125 - 9126
(2007/10/03)
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- A New Convenient Synthesis of Alkoxyanthracenes from Alkoxy-9,10- anthraquinones
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Methoxy-9,10-anthraquinones with mono-, di- and tetraether groups at different positions 1a-h can be directly reduced to the corresponding methoxyanthracenes 3a-h in moderate to good yields by zinc in refluxing acetic acid. Under similar conditions, ethyl 1′-anthracenoxyacetate (3i) with the ester group unaffected and 1,8-oxybis(ethyleneoxyethyleneoxy)anthracene (5) were also conveniently synthesized in 65 and 70% yields, respectively.
- Lu, Lingang,Chen, Qiyin,Zhu, Xiaozhang,Chen, Chuanfeng
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p. 2464 - 2466
(2007/10/03)
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- Total synthesis of (-)-balanol
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The efficient total synthesis of (-)-balanol, a potent inhibitor of the protein kinase C, is described (-)-Balanol consists of a chiral hexahydroazepine-containing fragment and a benzophenone fragment, both of which were prepared via novel synthetic routes. The hxahydroazepine fragment was prepared in racemic form through either Bu3SnH- or SmI2-promoted radical cyclization of oxime ethers 2ab intramolecularly connected with the formyl group. SmI2-promoted radical cyclization of 2b was found to be particularly successful in the selective synthesis of the seven-membered trans-amino alcohol 8b. Preparation of the enantiomerically pure hexahydroazepine-containing fragment was achieved through the enantioselective enzymatic acetylation of racemic alcohol 9, employing the immobilized lipase from Pseudomonas sp. The benzophenone fragment was prepared in short steps through a biomimetic oxidative anthraquinone ring cleavage starting from commercially available natural chrysophanic acid 15c. This reaction proceeded via [4 + 2]-cycloaddition of single of oxygen to anthracene derivative 17c, followed by Baeyer-Villiger-type rearrangement of the resulting hydroperoxide to afford the benzophenone derivatives 22 and 23.
- Miyabe, Hideto,Torieda, Mayumi,Inoue, Kyoko,Tajiri, Kazumi,Kiguchi, Toshiko,Naito, Takeaki
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p. 4397 - 4407
(2007/10/03)
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- Stereoselective synthesis of concave spacers for long-range electron transfer models
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Syntheses of concave spacers (9, 27) proceeded via stereoselective Diels-Alder reactions. Successful preparation of asymmetrical spacer 27 relied on regioselective protection of mutual precursor 7.
- Ryan, Daniel E.
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p. 6089 - 6092
(2007/10/03)
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- 2-Anthracenonyl acetic acids as 5-lipoxygenase inhibitors
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The synthesis of 2-substituted anthracenonyl acetic acid (2-AA) derivatives is described. The key step is the Marschalk reaction of 1-hydroxy-8-methoxy-anthracenedione with glycolic acid. After protection of the resulting 2-anthracenonyl acetic acid derivative, the 2-monoalkylated derivatives are selectively obtained by direct alkylation. The methodology proves quite general and allows for the introduction of various substituents onto the 2-position of the carboxylic side chain. Reduction of the anthracenediones proceeds with concomitant protecting group removal and proves final 2-AA products in good yields. The results of initial biological studies demonstrate enhanced 5-lipoxygenase inhibition compared to anthralin.
- Prinz, Helge,Mueller, Klaus
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p. 262 - 266
(2007/10/03)
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- BeCl2 as a new highly selective reagent for dealkylation of aryl-methyl ethers
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An efficient and simple method is introduced for the selective removal of methyl group from poly aryl-methyl ethers, in some important derivatives of benzophenones, xanthones, anthraquinones, aryl esters, benzamides and nitroanisoles with BeCl2.
- Sharghi, Hashem,Tamaddon, Fatemeh
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p. 13623 - 13640
(2007/10/03)
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- Asymmetric Diels-Alder Reactions of (S)-2-(p-Tolylsulfinyl)-1,4-naphthoquinones
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The asymmetric Diels-Alder reactions of (S)-2-(p-tolylsulfinyl)-1,4-naphthoquinones 1a-c with cyclic dienes have been explored.The high ? facial diastereoselectivity observed can be reversed in the presence of ZnBr2.Evidence is presented to show that the regiochemical outcome of these reactions is controlled only by the sulfinyl group.The in situ cycloaddition/pyrolytic sulfoxide elimination starting from chiral 1a-c offers a convenient new route for the construction of enantiomerically pure 1,4-dihydro-9,10-anthraquinones (+)-10 and (+)-12a-c.
- Carreno, M. Carmen,Ruano, Jose L. Garcia,Urbano, Antonio
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p. 6870 - 6876
(2007/10/02)
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- Preparation of Anthraquinones from 10-Hydroxy-9-anthracenecarbonitriles Obtained from a Novel Aryne Annulation Reaction
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A new method for brief regioselective synthesis of anthraquinones via the reaction of anions of ethyl cyanoacetate or the anions of 2-(carbethoxyaryl)acetonitriles with arynes is described.
- Bhawal, Baburao M.,Khanapure, Subhash P.,Zhang, Hongming,Biehl, Edward R.
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p. 2846 - 2849
(2007/10/02)
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- Obtention of anthraquinones by selective oxidation of the corresponding anthracenes and 9,10-dimethoxyanthracenes with copper or zinc nitrate supported on silica gel
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Anthracene, 9,10-dimethoxyanthracene and substituted analogues are selectively oxidized to the corresponding anthraquinones in good yields by copper(II) or zinc(II) nitrate supported on silica gel; the ether groups at different position from 9 and 10 are unaffected.
- Anastasia,Allevi,Bettini,Fiecchi,Sanvito
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p. 1083 - 1084
(2007/10/02)
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- ESR Spectroscopic Detection of Intramolecular Interactions in Radical Cations of Poly(α-methoxy)triptycenes
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-Cycloaddition of 1,4-benzoquinone to the di- and tetra(α-methoxy)anthracenes 11 yields the diketones 12 which undergo an acid-catalyzed rearrangement to the triptycene hydroquinones 13.Methylation of 13 affords the poly(α-methoxy)triptycenes 4.Aluminium chloride in nitromethane oxidizes the triptycenes 4 to the radical cations 4+* having one 1,4-dialkoxybenzene ring (4b+*, 4c+*, 4e+*) or two (4a+*) or three (4d+*), respectively, of such potential radical centers.The protons of the radical center give rise to hyperfine splittings which are very similar to those found in the ESR spectra of simple cis-1,4-dialkoxybenzene radical cations.The other aromatic protons, but not the bridgehead protons, exhibit a long range hyperfine coupling of 0.011 mT.Selective line broadening in the ESR spectrum of the radical cation 4a+* indicates that intramolecular electron transfer between the 1,4-dimethoxybenzene moieties occurs at a moderate rate.The deceleration of the exchange rate compared to the rate expected for a free radical cation is interpreted in terms of ion pairing.
- Quast, Helmut,Fuchsbauer, Hans-Lothar
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p. 1016 - 1038
(2007/10/02)
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- Selective Dealkylation of Methoxyanthraquinones via Difluoro1,O9>boron Chelates: Synthesis of Hydroxymethoxyanthraquinones
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1,8-, 1,5- 1,2-, and 1,4-Dimethoxyanthraquinones have been treated with boron trifluoride-diethyl ether to give difluoro(anthraquinonato)boron chelates (1a-d) respectively. 1,4,5-Trimethoxyanthraquinone was similarly converted separately in benzene and toluene into the mono- (2) and bis-difluoroboron(3)-chelates respectively, and 2,2',4,4'-tetramethoxybenzophenone was converted by BF3*Et2O in toluene into the boron adduct (4).Treatment of these derivatives, (1a-d) and (2)-(4), with methanol gave the following uncomplexed derivatives in good yield respectively: 1-hydroxy-8-methoxyanthraquinone, 1-hydroxy-5-methoxyanthraquinone, 1-hydroxy-2-methoxyanthraquinone, 1-hydroxy-4-methoxyanthraquinone, 4-hydroxy-1,5-dimethoxyanthraquinone, 1,4-dihydroxy-5-methoxyanthraquinone, and 2-hydroxy-2',4,4'-trimethoxybenzophenone.
- Preston, Peter N.,Winwick, Thomas,Morley, John O.
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p. 1439 - 1441
(2007/10/02)
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- Selective Demethylation of Di- and Tri-methoxyanthraquinones via Aryloxydifluoroboron Chelates. Synthesis of 4-Hydroxy-1,5-dimethoxyanthraquinone and 1,4-Dihydroxy-5-methoxyanthraquinone
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Methoxyanthraquinone derivatives react with boron trifluoride-diethyl ether to give mono- and bis-difluoroboron chelates which, in methanol, are converted into hydroxyanthraquinones; an extension of this method is described for the synthesis of 2-hydroxy-2',4,4'-trimethoxybenzophenone.
- Preston, Peter N.,Winwick, Thomas,Morley, John O.
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- A New Route to Anthraquinones
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The lithium salts derived from position 3 of phthalides react with arynes to form adducts, which, upon aerial oxidation, produce anthraquinones in moderate to good yields.Substituted phthalides and arynes also participate in this general reaction.The addition to unsymmetrically substituted arynes shows regioselectivity, whilst the availability of a new general route to phthalides extends the scope of this reaction.
- Dodsworth, David J.,Calcagno, Maria-Pia,Ehrmann, E. Ursula,Devadas, Bhatt,Sammes, Peter G.
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p. 2120 - 2124
(2007/10/02)
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- Process for the preparation of dimethoxyanthraquinones
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Dimethoxyanthraquinones can be prepared in high purity and in good yield in an economic manner which does not pollute the environment when 1 part by weight of dinitroanthraquinone is reacted with 2-8 parts by weight of methanol and 0.5-1.5 parts by weight of potassium hydroxide until all of the nitro groups have been replaced; the reaction is preferably carried out in the presence of 0.05-0.5 part by weight of amidosulphonic acid.
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