- Highly regioselective Diels-Alder reactions of 9-substituted anthracenes and 2-acetamidoacrylate: Synthesis of conformationally constrained α-amino acids
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The highly regioselective Diels-Alder reactions of 9-substituted anthracenes and 2-acetamidoacrylate afford a series of novel and conformationally constrained bicyclic bisaryl α-amino acids.
- Yang, Bingwei V.,Doweyko, Lidia M.
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- Substituted 9-Anthraldehydes from Dibenzocycloheptanol Epoxides via Acid-Catalyzed Epoxide Opening/Semipinacol Rearrangement
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Starting from benzaldehyde derivatives, the corresponding dibenzocycloheptenol could be prepared in five steps. Under both substrate (secondary vs tertiary alcohol and the substituents on the aromatic ring(s)) and condition control, the subsequent epoxidation and acid-catalyzed epoxide opening/semipinacol rearrangement/aromatization afforded the corresponding 9-anthraldehydes in good yields, up to 88% over two steps. The presence of the electron-withdrawing group(s) on the aromatic ring(s) suppressed the rate of the epoxidation while the subsequent semipinacol rearrangement step required heating; the presence of the electron-donating group(s), on the other hand, frequently led to the decomposition during the epoxidation. From the mechanistic studies, the semipinacol rearrangement of the epoxide could precede the ionization at the bisbenzylic position, yielding the aldehyde intermediate. The ensuing dehydrative aromatization led to the formation of 9-anthraldehyde. Conversely, nucleophilic addition to the aldehyde and dehydrative aromatization with concomitant loss of formic acid led to anthracene.
- Phumjan, Tanawat,Songthammawat, Poramate,Jongcharoenkamol, Jira,Batsomboon, Paratchata,Ruchirawat, Somsak,Ploypradith, Poonsakdi
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p. 13322 - 13349
(2021/09/13)
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- Ni-catalyzed reductive decyanation of nitriles with ethanol as the reductant
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A nickel-catalyzed reductive decyanation of aromatic nitriles has been developed, in which the readily available and abundant ethanol was applied as the hydride donor. Various functional groups on the aromatic rings, such as alkoxyl, amino, imino and amide, were compatible in this catalytic protocol. Heteroaryl, benzylic and alkenyl nitriles were also tolerated. Mechanistic investigation indicated that ethanol provided hydride efficientlyviaβ-hydride elimination in this reductive decyanation.
- Wu, Ke,Ling, Yichen,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Jin, Liqun,Hu, Xinquan
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supporting information
p. 2273 - 2276
(2021/03/09)
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- Unraveling relation between nonlinear absorption and structure of push pull ornamented anthracenyl chalcone derivatives
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Using green chemical method a series of fifteen systematically substituted 3-(9-substituted anthracen-10-yl)-1-(4-phenyl substituted)prop-2-en-1-one derivatives having high nonlinear absorption coefficient have been synthesized. The nonlinear absorption properties of these compounds were studied using nanosecond pulses at 532 nm wavelength. All 15 derivatives are found to show high nonlinear absorption in the range of 35–640 cm/GW. Among these the derivatives with –NO2 as one of the substitution group show higher nonlinear absorption. The origin of high nonlinear absorption with low linear absorption in the compounds has been attributed to two-step two-photon absorption process. We have shown that the energy bands of these compounds are distributed such that for excitation at 532 nm they have strong nonlinear absorption. These properties of the reported compounds make them a potential candidate for biological imaging and other applications which are based on nonlinear absorption.
- Chari, Rama,Jayabalan, J.,Saha, Amrita,Singh, Asha
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- Ni-Catalyzed cross-coupling of aryl thioethers with alkyl Grignard reagents via C-S bond cleavage
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A Ni-catalyzed cross-coupling of aryl thioethers with alkyl Grignard reagents, accompanied by the cleavage of the C(aryl)-SMe bond, has been presented. This method is distinguished by its mild conditions and moderate functional group tolerance, such as hydroxyl, halogen, and heterocycles, which should provide a straightforward access to the modification of sulfur-containing molecules.
- Zhu, Dan,Shi, Lei
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supporting information
p. 9313 - 9316
(2018/08/29)
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- Efficient and selective hydrogenation of C-O bonds with a simple sodium formate catalyzed by nickel
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A Ni-catalyzed hydrogenation of C-O compounds with sodium formate is developed. Various esters, i.e. aryl, alkenyl, benzyl pivalates, and even the aryl ethers, were efficiently reduced with a loading of nickel catalysts down to 0.5 mol%. Reactive functional groups such as C-C double bonds, carbonyl, CN, MeS and halogen groups are tolerable. This reaction can be used for the modification of complex molecules and carried out at a large scale.
- Xi, Xiaoxiang,Chen, Tieqiao,Zhang, Ji-Shu,Han, Li-Biao
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p. 1521 - 1524
(2018/02/19)
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- Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents
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The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [11C]-labeled PET tracer celecoxib.
- Heijnen, Dorus,Tosi, Filippo,Vila, Carlos,Stuart, Marc C. A.,Elsinga, Philip H.,Szymanski, Wiktor,Feringa, Ben L.
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supporting information
p. 3354 - 3359
(2017/03/17)
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- Nickel-catalyzed reductive cleavage of aryl alkyl ethers to arenes in absence of external reductant
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The reductive cleavage of the C-O bonds of aryl ethers has great potential in organic synthesis. Although several catalysts that can promote the reductive cleavage of aryl ethers have been reported, all such systems require the use of an external reductant, e.g., hydrosilane or hydrogen. Here, we report the development of a new nickel-based catalytic system that can cleave the C-O bonds of ethers in the absence of an external reductant. The hydrogen atom required in this new reductive cleavage reaction is provided by the alkoxy group of the substrate, which serves as an internal reductant. The absence of an external reductant enables the unique chemoselectivity, i.e., the selective reduction of an alkoxy group over alkenes and ketones. This journal is
- Tobisu, Mamoru,Morioka, Toshifumi,Ohtsuki, Akimichi,Chatani, Naoto
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p. 3410 - 3414
(2015/05/27)
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- Interaction of 9-substituted anthracenes with oxidation systems tert-butylhydroperoxide-metal tert-butoxide
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9-R-Anthracenes (R = Me, Ph) are effective acceptors of peroxyl and metalalkoxyl radicals in the systems tert-butylhydroperoxide-metal tert-butoxide (M = Al, V, Cr; C6H6, 20°C). Isolation of 9-R-9,10-dihydro-9,10-di-tert-butylperoxyanthracenes, 10-R-10-tert-butylperoxy-9-anthrones as major products reliably confirms the formation of tert-butylperoxy radicals and can be used for quantitative assessment of their content.
- Stepovik,Malysheva,Fukin
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p. 1401 - 1411
(2015/08/03)
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- Bismuth-catalyzed synthesis of anthracenes via cycloisomerization of o-alkynyldiarylmethane
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In this study, anthracenes were efficiently synthesized from o-alkynyldiarylmethane using a novel method that exploits the synergistic effect between Bi(OTf)3 as the catalyst, and trifluoroacetic acid (TFA). Through this reaction, we achieved the rapid and efficient synthesis of anthracenes bearing various functional groups under mild conditions.
- Park, Jungmin,Choi, Hyuck,Lee, Deug-Chan,Lee, Kooyeon
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supporting information
p. 7005 - 7007
(2015/11/27)
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- PREPARATION METHOD OF ANTHRACENE DERIVATIVES CATALYZED BY BISMUTH SALTS
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The present invention relates to a method for preparing an anthracene derivative by using a bismuth catalyst. The invention relates to a method for preparing an anthracene derivative simply and efficiently by using a bismuth catalyst and an acid additive. The preparation method allows obtaining a target material in a short time at a high yield by using a bismuth catalyst and an acid additive. Then, the prepared anthracene derivative may be used in a synthesis of intermediate in fine chemicals including pharmaceuticals and agricultural chemicals, and a synthesis of a variety of polymer materials having optical properties.COPYRIGHT KIPO 2015
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Paragraph 0121; 0122
(2017/01/02)
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- Features of the Diels-Alder reaction between 9,10-diphenylanthracene and 4-phenyl-1,2,4-triazoline-3,5-dione
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The Diels-Alder reaction between substituted anthracenes 1a-1j and 4-phenyl-1,2,4-triazoline-3,5 (2) is studied. In all cases except one, the reaction proceeds on the most active 9,10-atoms of substituted anthracenes. The orthogonality of the two phenyl groups at the 9,10-position of diene 1a is found to shield 9,10-reactive centers. No dienophiles with C=C bonds are shown to participate in the Diels-Alder reaction with 1a; however, the reaction 1a + 2 proceeds with the very active dienophile 2,4-phenyl-1,2,4-triazoline-3,5-dione. It is shown that attachment occurs on the less active but sterically accessible 1,4-reactive center of diene 1a. The structure of adduct 3a is proved by 1H and 13C NMR spectroscopy and X-ray diffraction analysis. The following parameters are obtained for reaction 1a + 2 ? 3a in toluene at 25°C: Keq = 2120 M-1, ΔHf≠ = 58.6 kJ/mol, ΔSf≠ = -97 J/(mol K), ΔVf≠ = -17.2 cm3/mol, ΔHb ≠ = 108.8 kJ/mol, ΔSb≠ = 7.3 J/(mol K), ΔVb≠ = -0.8 cm3/mol, ΔHr-n = -50.2 kJ/mol, ΔSr-n = -104.3 J/(mol K), ΔVr-n = -15.6 cm3/mol. It is concluded that the values of equilibrium constants of the reactions 1a-1j + 2 ? 3a-3j vary within 4 × 101-1011 M-1.
- Kiselev,Kornilov,Kashaeva,Potapova,Krivolapov,Litvinov,Konovalov
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p. 2073 - 2080
(2015/02/19)
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- An efficient dehydroxymethylation reaction by a palladium catalyst
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A general method for selective dehydroxymethylation has been discovered by using widely available Pd(OAc)2. The present study offers a new synthetic strategy for the regioselective functionalization by employing the steric, electronic and coordinating nature of the hydroxymethyl (-CH 2OH) group temporarily.
- Modak, Atanu,Naveen, Togati,Maiti, Debabrata
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supporting information
p. 252 - 254
(2013/02/22)
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- Flexible and practical synthesis of anthracenes through gold-catalyzed cyclization of o -alkynyldiarylmethanes
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A concise gold-catalyzed method for the preparation of anthracenes from o-alkynyldiarylmethanes has been developed. Under mild reaction conditions, versatile anthracene derivatives were formed in moderate to good yields. The high flexibility, broad substrate scope, and mild nature of this reaction render it a viable alternative for the synthesis of anthracenes.
- Shu, Chao,Chen, Cheng-Bin,Chen, Wei-Xi,Ye, Long-Wu
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p. 5542 - 5545
(2013/11/19)
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- A Palladium Bipyridyl Complex Grafted onto Nanosized MCM-41 as a Heterogeneous Catalyst for Negishi Coupling
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The Negishi coupling of aryl bromides or acyl chlorides with organozinc chlorides catalyzed by a palladium bipyridyl complex anchored on nanosized mobile crystalline material 41 (MCM-41) were investigated. The reactions proceeded smoothly with a very low catalyst loading in THF at 70°C for electron-deficient aryl bromides, which gave good to high yields of the Negishi coupling products. However, reactions in toluene at 110°C were required if electron-rich aryl bromides were employed. For acyl chlorides, the reactions could be performed in THF at 50°C and the corresponding ketones and ynones were obtained in high yields. After centrifugation, it was possible to easily recover the supported catalyst from the reaction mixture, and this could be reused several times without any retreatment or regeneration with only a slight decrease in activity.
- Wu, Wei-Yi,Lin, Tze-Chiao,Takahashi, Tamotsu,Tsai, Fu-Yu,Mou, Chung-Yuan
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p. 1011 - 1019
(2013/05/09)
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- Tf2O-catalyzed Friedel-Crafts alkylation to synthesize dibenzo[a,d]cycloheptene cores and application in the total synthesis of Diptoindonesin D, Pauciflorial F, and (±)-Ampelopsin B
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By using Tf2O as a catalyst, we have developed a protocol for the preparation of various dibenzo[a,d]cycloheptene cores via Friedel-Crafts alkylation. Using this method as the key step, we also present concise and useful routes to synthesize the natural products Diptoindonesin D, Pauciflorial F, and (±)-Ampelopsin B. Notably, this process exhibited following very attractive features: (i) the process is metal free, with only catalytic amounts of Tf2O being employed, and (ii) the process is simple and environmentally conscious, avoiding the use of excess amounts of base, oxidant, or other additives.
- Wang, Gang-Wei,Wang, Hong-Li,Capretto, David A.,Han, Qi,Hu, Rong-Bin,Yang, Shang-Dong
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experimental part
p. 5216 - 5222
(2012/08/08)
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- Fluorous oxime palladacycle: A precatalyst for carbon-carbon coupling reactions in aqueous and organic medium
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To facilitate precatalyst recovery and reuse, we have developed a fluorous, oxime-based palladacycle 1 and demonstrated that it is a very efficient and versatile precatalyst for a wide range of carbon-carbon bond formation reactions (Suzuki-Miyaura, Sonogashira, Stille, Heck, Glaser-type, and Kumada) in either aqueous or organic medium under microwave irradiation. Palladacycle 1 could be recovered through F-SPE in various coupling reactions with recovery ranging from 84 to 95% for the first cycle. Inductively coupled plasma optical emission spectrometry (ICP-OES) analyses of the Pd content in the crude product from each class of transformation indicated extremely low levels of leaching and the palladacycle could be reused four to five times without significant loss of activity.
- Susanto, Woen,Chu, Chi-Yuan,Ang, Wei Jie,Chou, Tzyy-Chao,Lo, Lee-Chiang,Lam, Yulin
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experimental part
p. 2729 - 2742
(2012/05/21)
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- Indium-catalyzed construction of polycyclic aromatic hydrocarbon skeletons via dehydration
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Polycyclic aromatic compounds can be synthesized from 2-benzylic- or 2-allylbenzaldehydes using a catalytic amount of In(III) or Re(I) complexes. By using this method, polycyclic aza-aromatic compounds can also be prepared efficiently. In these reactions, only water is formed as a side product.
- Kuninobu, Yoichiro,Tatsuzaki, Tomohiro,Matsuki, Takashi,Takai, Kazuhiko
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experimental part
p. 7005 - 7009
(2011/10/09)
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- Dynamic Covalent chemistry: A facile room-temperature, reversible, diels-alder reaction between anthracene derivatives and n-phenyltriazolinedione
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A series of readily accessible, dynamic Diels-Alder reactions that are reversible at room temperature have been developed between anthracene derivatives as dienes and N-phenyl-1,2,4-triazoline-3,5-dione as the dienophile. The adducts formed undergo reversible component exchange to form dynamic libraries of equilibrating cycloadducts. Furthermore, reversible adduct formation allows temperature-dependent modulation of the fluorescent properties of anthracene components; a feature of potential interest for the design of optodynamic polymeric materials by careful selection and manipulation of these simple dienes and dienophiles. Copyright
- Roy, Nabarun,Lehn, Jean-Marie
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supporting information; experimental part
p. 2419 - 2425
(2012/07/03)
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- Ni-catalyzed reduction of inert C-O bonds: A new strategy for using aryl ethers as easily removable directing groups
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An efficient Ni-catalyzed protocol for the reductive cleavage of inert C-O bonds has been developed. The method is characterized by its simplicity and wide scope, thereby allowing the use of aryl ethers as easily removable directing groups in organic synthesis.
- Alvarez-Bercedo, Paula,Martin, Ruben
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supporting information; experimental part
p. 17352 - 17353
(2011/02/23)
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- Flow-vacuum pyrolysis of dibenzocycloheptane derivatives on zeolites catalysts. IV
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The pyrolysis of 10,11-dihydro-5H-dibenzo[a,d]cicloheptadien-5-ol (4) and of 5H-dibenzo[a,d]cycloheptatrien-5-ol (5) in flowvacuum conditions (advanced vacuum, inert atmosphere) on zeolites at 300°C is presented. The reaction products were identified by GC/MS using authentic samples and a reaction mechanisms involving cationic species as intermediates were proposed. A comparison with the pyrolysis of the same compounds performed in FVP conditions on quartz is presented.
- Istrati, Daniela,Parvulescu, Luminitza,Popescu, Angela,Mihaiescu, Dan,Badea, Florin
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scheme or table
p. 711 - 714
(2011/10/02)
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- X-ray structure of a CT complex relevant to Diels-Alder reactivity of anthracenes
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(Chemical Equation Presented) Combining the results of thermodynamic and kinetic investigations with an X-ray characterization of a transient CT complex sheds more light on the Diels-Alder reactivity of a strongly electron-deficient olefin, namely the 4-n
- Berionni, Guillaume,Bertelle, Pierre-Alexandre,Marrot, Jerome,Goumont, Regis
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scheme or table
p. 18224 - 18225
(2010/04/24)
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- An experimental and theoretical study on the electrostatic effect of an appended cationic group on electronic properties of aromatic systems
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Tetraalkylammonium salts, characterized by an aromatic system pending from one of the alkyl chains, are taken as model systems to study the spectroscopic and redox properties of the aromatic centre under the field effects exerted by the charged group through alkyl bridges of varying length. The changes in the aromatic's redox properties, due to the net field effect and its different components, are interpreted on theoretical bases. the Owner Societies.
- Grosso, Viviana,Previtali, Carlos,Chesta, Carlos A.,Vera, D. Mariano A.,Pierini, Adriana B.
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p. 5988 - 5996
(2008/09/21)
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- Unusual demethylation of O,O′-dimethyl chlorothiophosphate with aryllithiums
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The reaction of O,O′-dimethyl chlorothiophosphate with aryllithiums took place easily to afford the corresponding methylated aryl compounds in place of expected O,O′-dimethyl aryl(thiophosphonate)s. Copyright
- Ribeiro, Nigel,Maeda, Jin,Ishida, Yasuhiro,Kobayashi, Yuka,Saigo, Kazuhiko
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p. 1412 - 1413
(2008/03/14)
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- Charge transfer complex formation between p-chloranil and 1,n-di(9-anthryl)alkanes
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Dimer model compounds of polyvinylanthracenes (1,n-di(9-anthryl)alkanes, when n = 1-5) were synthesized to model the effects of distance and orientation between anthracene groups in polymeric systems. Charge transfer (CT) complexes of anthracene, 9-methylanthracene and 1,n-di(9-anthryl)alkanes with p-chloranil (p-CHL) have been investigated spectrophotometrically in dichloromethane. The colored products are measured spectrophotometrically at different wavelength depending on the electronic transition between donors and acceptor. The formation constants of the CT complexes were determined by the Benesi-Hildebrand equation. The thermodynamic parameters were calculated by Van't Hoff equation. Stochiometries of the complexes formed between donors and acceptor were defined by the Job's method of the continuous variation and found in 1:1 complexation with donor and acceptor at the maximum absorption bands.
- Arslan, Mustafa,Masnovi, John
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p. 711 - 716
(2007/10/03)
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- Emission factors and importance of PCDD/Fs, PCBs, PCNs, PAHs and PM 10 from the domestic burning of coal and wood in the U.K.
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This paper presents emission factors (EFs) derived for a range of persistent organic pollutants (POPs) when coal and wood were subject to controlled burning experiments, designed to simulate domestic burning for space heating. A wide range of POPs were emitted, with emissions from coal being higher than those from wood. Highest EFs were obtained for particulate matter, PM10, (～ 10 g/kg fuel) and polycyclic aromatic hydrocarbons (～ 100 mg/ kg fuel for ΣPAHs). For chlorinated compounds, EFs were highest for polychlorinated biphenyls (PCBs), with polychlorinated naphthalenes (PCNs), dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) being less abundant. EFs were on the order of 1000 ng/kg fuel for ΣPCBs, 100s ng/ kg fuel for ΣPCNs and 100 ng/kg fuel for ΣPCDD/Fs. The study confirmed that mono- to trichlorinated dibenzofurans, Cl1,2,3DFs, were strong indicators of low temperature combustion processes, such as the domestic burning of coal and wood. It is concluded that numerous PCB and PCN congeners are routinely formed during the combustion of solid fuels. However, their combined emissions from the domestic burning of coal and wood would contribute only a few percent to annual U.K. emission estimates. Emissions of PAHs and PM 10 were major contributors to U.K. national emission inventories. Major emissions were found from the domestic burning for Cl1,2,3DFs, while the contribution of PCDD/F-ΣTEQ to total U.K. emissions was minor.
- Lee, Robert G. M.,Coleman, Peter,Jones, Joanne L.,Jones, Kevin C.,Lohmann, Rainer
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p. 1436 - 1447
(2007/10/03)
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- Photochemical Reactions of α-Bromoacetylarenes Studied by Product Analysis and Laser Flash Photolysis
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The hydrogen abstraction reaction and rearrangement reaction of aroylmethyl radicals were studied by product analyses and transient absorption spectroscopies. The α-bromoacetylarenes examined in this study gave aroylmethyl radicals by C-Br bond cleavage u
- Suzuki, Toshiaki,Kaneko, Yuji,Ikegami, Masashi,Arai, Tatsuo
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p. 801 - 806
(2007/10/03)
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- A rationally designed universal catalyst for Suzuki-Miyaura coupling processes
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Unprecedented scope, reactivity, and stability are displayed by a new catalyst system. This was demonstrated with general and efficient syntheses of sterically hindered (hetero)biaryls (see examples shown), mild coupling reactions of alkyl boron derivatives, and rapid coupling reactions of aryl chlorides at room temperature.
- Walker, Shawn D.,Barder, Timothy E.,Martinelli, Joseph R.,Buchwald, Stephen L.
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p. 1871 - 1876
(2007/10/03)
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- Photocatalytic oxygenation of anthracenes and olefins with dioxygen via selective radical coupling using 9-mesityl-10-methylacridinium ion as an effective electron-transfer photocatalyst
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Visible light irradiation of the absorption band of 9-mesityl-10- methylacridinium ion (Acr+-Mes) in an O2-saturated acetonitrile (MeCN) solution containing 9,10-dimethylanthracene results in formation of oxygenation product, i.e., dimethylepidioxyanthracene (Me 2An-O2). Anthracene and 9-methylanthracene also undergo photocatalytic oxygenation with Acr+-Mes to afford the corresponding epidioxyanthracenes under the photoirradiation. In the case of anthracene, the further photoirradiation results in formation of anthraquinone as the final six-electron oxidation product, via 10-hydroxyanthrone, accompanied by generation of H2O2. When anthracene is replaced by olefins (tetraphenylethylene and tetramethylethylene), the photocatalytic oxygenation of olefins affords the corresponding dioxetane, in which the O-O bond is cleaved to yield the corresponding ketones. The photocatalytic oxygenation of anthracenes and olefins is initiated by photoexcitation of Acr+-Mes, which results in formation of the electron-transfer state: Acr?- Mes?+, followed by electron transfer from anthracenes and olefins to the Mes?+ moiety together with electron transfer from the Acr? moiety to O2. The resulting anthracene and olefin radical cations undergo the radical coupling reactions with O 2?- to produce the epidioxyanthracene (An-O 2) and dioxetane, respectively.
- Kotani, Hiroaki,Ohkubo, Kei,Fukuzumi, Shunichi
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p. 15999 - 16006
(2007/10/03)
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- Efficient heterogeneous oxidation of alkylarenes with molecular oxygen
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(Chemical Equation Presented) Ru(OH)x/Al2O 3 efficiently catalyzes the heterogeneous aerobic oxygenation or oxidative dehydrogenation of alkylarenes to give the corresponding oxygenated or dehydrogenated products. Catalyst/product separation is very easy, and the recovered catalyst is reusable with retention of the high catalytic performance.
- Kamata, Keigo,Kasai, Jun,Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 3577 - 3580
(2007/10/03)
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- Efficient oxidative aromatization of 9,10-dihydroanthracenes with molecular oxygen catalyzed by ruthenium porphyrin complex
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In the presence of a catalytic amount of a ruthenium porphyrin complex, various 9,10-dihydroanthracene derivatives were aromatized with molecular oxygen to the corresponding anthracenes. It was found that the addition of sulfuric acid accelerated the aromatization at room temperature under atmospheric pressure of oxygen to afford various anthracenes in high yields.
- Tanaka, Hirotaka,Ikeno, Taketo,Yamada, Tohru
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p. 576 - 578
(2007/10/03)
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- Oxidative aromatization of 9,10-dihydroanthracenes using molecular oxygen promoted by activated carbon
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Substituted 9,10-dihydroanthracenes were oxidatively aromatized to the corresponding anthracenes effectively by using molecular oxygen as an oxidant and activated carbon (Darco KB, Aldrich, Inc.) as a promoter in xylene.
- Nakamichi, Natsuki,Kawabata, Hirotoshi,Hayashi, Masahiko
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p. 8272 - 8273
(2007/10/03)
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- Flow-vacuum pyrolysis of polycyclic compounds. 151 pyrolysis of three RELATED dibenzocycloalkanols
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The flow-vacuum pyrolyses of cis-9,10-bis(hydroxymethyl)-9,10-dihydroanthracene (4); 6H-5,7-dihydrodibenzo[a,c]cyclohepten-6-ol (5) and 5H-dibenzo[a,d]cyclohepten-5-ol (6) were studied at 1.33 mbar in argon atmosphere over a large temperature interval. The main pyrolysis product of 4-cis was anthracene (13), accompanied by traces of 9-methylanthracene (15) and 9-anthraldehyde (14). The main pyrolysis products of 5 were: 9-methylphenanthrene (17) and 5H-dibenzo[a,c]cycloheptene (16), whereas phenanthrene (19) and fluorene (18) were minor products. From the flow-vacuum pyrolysis of 6 the corresponding ketone (dibenzosuberenone 12) and 5H-dibenzo[a,d]cycloheptene (20) were the major products and anthracene and 9-methylanthracene the minor ones. The thermal behavior of 4-cis, 5 and 6 was rationalized on the basis of mechanisms including radical and concerted steps. Some parts of the here proposed mechanisms were confirmed by our previous works describing the conversions of authentic 16 and 20 to the same end-products: 17 + 19, respectively 13 + 15. A comparison with the thermal behaviour of other related dibenzocycloalkanols is also made.
- Banciu, Mircea D.,Popescu, Angela,Parvulescu, Lumini?a,Ciuculescu, Crinu,Drǎghici, Constantin,Banciu, Anca,Mihǎiescu, Dan
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p. 239 - 248
(2007/10/03)
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- Acid-catalysed aromatization of anthranyl derivatives. A kinetic and thermodynamic study
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The acid-catalysed solvolysis reaction of 9-methoxy-9-methyl-9,10-dihydroanthracene (2-OMe) in 50 vol percent acetonitrile in water at 25°C provides the substitution product 9-hydroxy-9-methyl-9,10-dihydroanthracene (2-OH) and the elimination product 9-methylanthracene (3). The rate-ratio of substitution-to-elimination was measured as kS/kE = 0.93. The alcohol also undergoes acid-catalysed aromatization to give the thermodynamically favoured product 3. The reaction enthalpy of this dehydration reaction was measured as ΔH = -10.2 ± 1.0 kcal mol-1. The corresponding reaction of the secondary alcohol 9-hydroxy-9,10-dihydroanthracene (1-OH) has a reaction enthalpy of ΔH = -12.3 ± 0.8 kcal mol-1. Addition of azide ion (0.25 M) gives rise to a large fraction of azide adduct 2-N3, which rapidly undergoes solvolysis. The "azide-clock" method yields rate constants for reaction of the carbocation to give alcohol and elimination product ofkw = 2.2 × 108 s-1 and ke = 2.4 x 108 s-1, respectively. The thermodynamic stability of the carbocation was estimated as pKR = -9.1. The alkene 9-methylene-9,10-dihydroanthracene (4) undergoes a slow acid-catalysed aromatization to give 3; no competing formation of 2-OH was observed.
- Pirinccioglu,Jia,Thibblin
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p. 2271 - 2275
(2007/10/03)
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- Process for producing organic compounds by catalysis of imide compounds
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A process produces an organic compound by catalysis of an imide compound of Formula (1): wherein R1 and R2 are each an alkyl group, aryl group, cycloalkyl group, etc., where R1 and R2 may be combined to form a double bond, or an aromatic or non-aromatic ring; and X is an oxygen atom or a hydroxyl group. In this process, the imide compound catalyst is added in installments to the reaction system to perform a reaction. Such reactions include, for example, oxidation reactions, carboxylation reactions, nitration reactions, sulfonation reactions, and carbon-carbon bond formation reactions. This process can produce a target compound with a higher conversion or selectivity in the production of the organic compound by catalysis of the imide compound catalyst such as N-hydroxyphthalimide.
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- Characterization of the combustion products of polyethylene
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Polyethylene (PE) was burned in a tube-type furnace with an air flow at a temperature of 600~900°C. Combustion products were collected with glass wool, glass fiber filter, and XAD-2 adsorbent. The analysis of the products was performed with GC-FID and GC-MSD. At low temperature, hydrocarbons were the major components, while at higher temperature the products were composed of polycyclic aromatic hydrocarbons. With the high performance of the Hewlett-Packard 6890GC-5973MSD, more compounds were identified in comparison with previous studies.
- Piao, Mingjun,Chu, Shaogang,Zheng, Minghui,Xu, Xiaobai
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p. 1497 - 1512
(2007/10/03)
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- Flow-vacuum pyrolysis of polycyclic compounds. 14: Pyrolysis of 10,11-dihydro-12H-dibenzo[a,d]cycloocten-5-one
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Flow-vacuum pyrolysis of the title ketone 10 at 1 mmHg and 800-1000°C was investigated using GC/MS. The intermediate occurrence of two dibenzocycloheptane hydrocarbons 15 and 16 followed by their conversion into more stable aromatic hydrocarbons namely anthracene (9), 9-methylanthracene (19), phenanthrene (3), 9-methylphenanthrene (18) and fluorene (14) was undoubtedly proved. The proposed reaction mechanism including two parallel reaction routes (fission of saturated framework and decarbonylation) is compared with pyrolysis mechanisms of related dibenzocycloalkane-ketones and -hydrocarbons.
- Banciu, Mircea D.,Costea, Cristina,Mihaiescu, Dan
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p. 867 - 873
(2007/10/03)
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- Mechanism and reactivity parameters of the reduction of arylmethyl radicals from time-resolved electron-photoinjection experiments
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The 9-anthrylmethyl, diphenylmethyl, benzyl, and 4-methylbenzyl radicals are generated by reduction of the corresponding chlorides with electrons photoinjected in laser pulse experiments. The 'polarograms' derived from the variation of the charge flowing through the electrode with the dc potential of the electrode represent the reduction of these radicals to the corresponding anions. The meaning of the half-wave potentials is investigated through their variations with the measurement time and with the addition of acids in the solution, which accelerates the disappearance of the carbanion. Correcting the kinetic data for the effect of radical dimerization, the reduction kinetics appear to be mostly under the control of the follow-up reaction of the carbanion with acids present in the medium, although the effect of charge-transfer kinetics begins to interfere at the lower end of the time window. The results are compared with earlier data obtained by other techniques. The changes in reactivity observed in the series are discussed with the help of density functional quantum chemical calculations.
- Gonzalez, Jose,Hapiot, Philippe,Konovalov, Valery,Saveant, Jean-Michel
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p. 10171 - 10179
(2007/10/03)
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- Flow-vacuum pyrolysis of polycyclic compounds. 12: Pyrolysis of 10,11-dihydro-5-methylene-5H-dibenzo[a,d]cycloheptene and of 10,11-dihydro-5-methyl-5H-dibenzo[a,d]cycloheptene
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Flow-vacuum pyrolyses of the title hydrocarbons afford anthracene and 9-methylanthracene as main products. The reaction mechanism suggested by Trahanovsky 2 for pyrolysis of dibenzocyclooctene- and dibenzocycloheptene derivatives is confirmed. For secondary products, parallel radicalic routes are suggested.
- Banciu, Mircea D.,Mangra, Cristina,Petride, Aurica
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p. 565 - 569
(2007/10/03)
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- Palladium-Catalyzed Methylation of Aryl and Vinyl Halides by Stabilized Methylaluminum and Methylgallium Complexes
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The intramolecularly stabilized mono- and dialkylaluminum complexes 1a, 2, 3, 4a, 5a, 5c, 6a, 6c, 7, 8, and 9 in the presence of palladium catalysts, cross-alkylate aryl, vinyl, and benzyl bromides and iodides under mild standard laboratory conditions. Aryl bromides with carbonyl substituents or benzylic halides are converted partially into dialkyl compounds. Under similar conditions, the analogous stabilized dimethylgallium complexes 1b, 4b, 5b, 6b, and 10 methylate aryl and vinyl bromides and iodides in a highly selective manner. Substituted bromobenzenes XC6H4Br, where X = CHO, COPh, CO2Et, CN, NO2, Cl, CH2Br, or CH=CHCOPh, are methylated by the organogallium reagents usually only at the aromatic ring halogen atom to give substituted toluenes as single products. The methylation rates were shown to depend on the nature of the chelating ligands, on the solvent, and on the type of palladium catalyst employed.
- Blum, Jochanan,Gelman, Dmitri,Baidossi, Wael,Shakh, Eduard,Rosenfeld, Ayelet,Aizenshtat, Zeev,Wassermann, Birgit C.,Frick, Michael,Heymer, Bernd,Schutte, Stefan,Wernik, Sonja,Schumann, Herbert
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p. 8681 - 8686
(2007/10/03)
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- A novel antenna cyclodextrin: Synthesis and photosensitized reaction of an included guest
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A novel water-soluble photochemical microreactor has been prepared. A perbutylated cyclodextrin bearing seven naphthalenesulfonate antenna chromophores (Bu-CD-N7) displays improved solubilization of hydrophobic guests in comparison with the unbutylated material (CD-N7). The photophysical properties of Bu-CD-N7 are similar to those of the CD-N7. The naphthyl chromophores of Bu-CD-N7 were used to sensitize the photolysis of 9-anthrylmethyl pivalate (AP). Inclusion of AP in the cyclodextrin leads to the selective formation of one of the two possible coupling products.
- Nowakowska, Maria,Loukine, Nikolai,Gravett, David M.,Burke, Nicholas A. D.,Guillet, James E.
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p. 4364 - 4368
(2007/10/03)
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- Radiation-Induced C-C Bond Cleavage in 1,2-Diarylethanes as Model Compounds of Coal, Part 3. Pulse and Steady-State Radiolysis of 1,2-Di(9-anthryl)ethane in Organic Solvents
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1,2-Di(9-anthryl)ethane (1,2-DAE) was used as a model for coal to study the C-C bond cleavage of the ethano linkage in the radiolysis of solutions containing NaAlH2(OCH2CH2OCH3)2.Transient species were investigated by pulse radiolysis of solutions of 1,2-DAE in THF, DME and toluene in the absence and the presence of NaAlH2(OR)2.In the presence of NaAlH2(OR)2 stabilized, long-lived radical anion/sodium cation pairs of 1,2-DAE were generated even in the non-polar solvent toluene.The reaction mechanisms differ substantially for solutions in the ether solvents (THF or DME) and for solutions in toluene.Steady-state radiolysis (60Co γ-rays) of solutions of 1,2-DAE in toluene containing NaAlH2(OR)2 resulted in the C-C bond cleavage of the ethano linkage.This is attributed to the unstable dianion (1,2-DAE(2-), 2Na(1+)) formed in two successive radiation-induced reductions via (1,2-DAE)(.-), Na(1+)).The resulting (9-anthryl)methyl carbanionic fragments C14H9CH2(1-), Na(1+) react with AlH(OR)2 generated in the process, to form the aluminate salts .From the aluminate salts, 9-methylanthracene (9-MA) was obtained by hydrolysis in yields up to 65 wt.percent. - Keywords: Radiolysis, C-C Bond Cleavage, 1,2-Diarylethane, Aluminium Hydride Reagent, Transient Spectroscopy
- Haenel, Matthias W.,Richter, Udo-Burckhard,Solar, Sonja,Getoff, Nikola
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p. 303 - 311
(2007/10/02)
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- FLOW-VACUUM PYROLYSIS OF POLYCYCLIC COMPOUNDS. 8. PYROLYSIS OF 5H-DIBENZOCYCLOHEPTENE AND 10,11-DIHYDRO-5H-DIBENZOCYCLOHEPTENE
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Flow-vacuum pyrolyses of 5H-dibenzocycloheptene (1) and 10,11-dihydro-5H-dibenzocycloheptene (7) were studied at 1 Torr and different temperatures between 400 deg C and 800 deg C.The main reaction products were, in both cases, 9-methylanthracene (3) and anthracene (2) occurring in different sequences: 3 then 2 in pyrolyses of 1 and 2 then 3 in pyrolyses of 7.Hydrocarbon 7 is thermally more stable than 1.Reaction mechanisms including radicalic and concerted steps were suggested.For hydrocarbon 1 a comparison with the previously described (Pomerantz2) results of pyrolyses in static system is given.
- Banciu, Mircea D.,Enescu, Rodica,Cira, Ovidiu,Banciu, Anca,Petride, Auriga
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p. 1449 - 1455
(2007/10/02)
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- INVESTIGATION OF THE COMPOSITION OF PETROLEUM ANTHRACENE HYDROCARBONS
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The optimum conditions of adduct formation with maleic anhydride for the isolation of ca. 100percent anthracene hydrocarbons from a mixture with phenanthrenes and other compounds are set out.Gas-liquid chromatography has been used to study the individual composition of anthracene and C1-C3 anthracenes isolated by the method proposed from concentrates of triaromatic hydrocarbons of crude oils from the Okha, Katangli (Sakhalin) and Dorokhovsk (Urals-Volga) fields.With the aid of the individual compounds synthesized, for the first time 2-ethylanthracene and 1,3- and 2,3-dimethylanthracene have been identified in crude oils, and the retention indices have also been calculated for certain C2- and C3-substituted anthracene hydrocarbons for chromatographic phase SE-54.
- Ivanov, V. I.,Golovko, A. K.
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p. 504 - 512
(2007/10/02)
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- Structures and photoactivation of the charge-transfer complexes of Bis(arene)iron(II) dications with ferrocene and arene donors
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Ferrocene forms a series of unusual charge-transfer crystals with the isoelectronic bis(arene)iron(II) dication, in which X-ray crystallography establishes the alternate (heterosoric) stacking of sandwich structures comprising the donor-acceptor pairs. In acetonitrile, the 1:1 complex [Cp2Fe, Ar2Fe2+] shows a broad absorption band centered at λmax ～ 630 nm. Bis(arene)iron(II) acceptors also form highly colored crystals with various arene donors, in which the charge-transfer absorption (hvCT) derives from the same heterosoric stacking of donor-acceptor pairs-despite the structurally divergent nature of the arene (planar) and ferrocene (sandwich) donors. These absorptions undergo a predictable red-shift with increasing acceptor strength in the order (BZ)2Fe2+ > (MES)2Fe2+ > (DUR)2Fe2+ > (HMB)2Fe2+, as judged by the reduction potentials Eored of the benzene, mesitylene, durene, and hexamethylbenzene derivatives, respectively. Common to both classes of 1:1 bis(arene)iron(II) complexes [Ar2Fe2+, D], where D is either a ferrocene or arene donor, is the efficient photoinduced substitution of the arene ligands that occurs in solution when the charge-transfer bands are selectively irradiated with monochromatic light. Time-resolved picosecond spectroscopy identifies such a charge-transfer deligation to occur via the direct photoexcitation of the complex to the ion radical pair, i.e., [Ar2Fe2+, D] hvCT→ [Ar2Fe+, D?+], followed by the spontaneous loss of arene ligands by the acceptor moiety. Indeed, the substitution lability of the 19-electron intermediate Ar2Fe+ can be independently demonstrated by the application of transient electrochemical methods to the reduction of various bis(arene)iron(II) dications.
- Lehmann,Kochi
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p. 501 - 512
(2007/10/02)
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- Synthesis, structure, and dynamic properties of bis(cis-(benzylthio)stilbenethiolate) complexes of nickel(II), palladium(II), and platinum(II) and of related compounds
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The products of the reactions of the bis(cis-stilbenedithiolates) of Ni(II), Pd(II), and Pt(II) with benzyl halides are shown to be chelates of cis-(benzylthio)stilbenethiolate by chemical degradation, independent synthesis, and X-ray structural analyses. The isolated solid trans-anti isomers of M[(PhCH2)2S4C4Ph4] (M = Ni, Pd, Pt) are isomorphous and crystallize in space group P21/c with Z = 2. For M = Ni, a = 14.832 (3) ?, b = 8.814(2) ?, c = 14.867 (3) ?, β = 112.69 (2)°, and dcalcd = 1.344 (2) g cm-3. For M = Pd, a = 14.898 (3) ?, b = 8.805 (3) ?, c = 14.791 (3) ?, β = 110.98 (2)°, and dcalcd = 1.42 g cm-3. For M = Pt, a = 14.885 (4) ?, b = 8.828 (3) ?, c = 14.806 (6) ?, β = 111.04 (2)°, and dcalcd = 1.58 g cm-3. The central metal atoms of the nickel complex are in a slightly distorted planar ligand environment. The C-S(CH2Ph) bond lengths of 1.835 (2) ? are longer than normal due to electronic labilization. The complexes show dynamic behavior in solution primarily due to sulfur inversion processes, as evidenced by variable-temperature 1H NMR measurements. The trans-anti and trans-syn isomers are the pre-dominant species in solutions of the nickel complexes. In solutions of the complexes of Pd and Pt, the cis-anti isomers were also detectable; the cis-anti isomer of the Pt complex is more stable than that of Pd and can be isolated. Also synthesized were several aralkyl and substituted-benzyl complexes of the type M[RCH2)2S4C4Ph4], with M = Ni and R = 4-naphthyl, 9-anthracenyl, 4-CH3OC6H4-, and 4-NO2C6H4-H4-. All aralkyl dithiolenes are light-sensitive in solution. In a series of complexes with M = Ni, the rates of photodecomposition, which proceeds with C-S bond homolysis, increase with increasing electronic labilization of the C-S(aralkyl) bonds.
- Zhang, Cheng,Reddy, Hussain K.,Schlemper, Elmer O.,Schrauzer, Gerhard N.
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p. 4100 - 4103
(2008/10/08)
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- Synthesis of (5R,10S,11R)-(+)-10,11-Dihydro-5-methyl-5H-dibenzocyclohepten-5,10-imin-11-ol: A Hydroxylated Metabolite of MK-0801
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Two approaches to the synthesis of the MK-0801 metabolite, (5R,10S,11R)-(+)-10,11-dihydro-5-methyl-5H-dibenzocyclohepten-5,10-imin-11-ol (1a), from dibenzosuberenone (2) are presented.Selective ring opening of an aziridine with acetyl bromide and inversion of the stereochemistry provide 1a.Alternatively, formation of an oxazolidinone ring at the 10,11-position of the suberenone via a bromohydrin (9) is followed by acid-catalyzed cyclization of the oxazolidinone-carbinol 12 to provide 1a.A practical resolution for obtaining the active 5R,10S,11R-(+) enantiomer is described.
- Larsen, Robert D.,Davis, Paul,Corley, Edward G.,Reider, Paul J.,Rothauser Lamanec, Theresa,Grabowski, Edward J. J.
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p. 299 - 304
(2007/10/02)
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- Bimolecular Reactions of 3-Methylene-1,4-cyclohexadiene (p-Isotoluene), 5-Methylene-1,3-cyclohexadiene (o-Isotoluene), 1-Methylene-1,4-dihydronaphthalene (Benzo-p-isotoluene), and 9-Methylene-9,10-dihydroanthracene (Dibenzo-p-isotoluene)
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3-Methylene-1,4-cyclohexadiene, 1, 5-methylene-1,3-cyclohexadiene, 2, 1-methylene-1,4-dihydronaphthalene, 5, and 9-methylene-9,10-dihydroanthracene, 8, react with second-order kinetics in benzene solution.The activation parameters for the reaction of 1,5,and 8, especially the frequency factor, suggest a nonconcerted reaction with little orientational demand in the transition state.The frequency factor for the reaction of 2 suggests a concerted pathway.The product distribution from each compound reinforces the kinetic observations.The products from the pyrolysisof 1 could be rationalized by a radical cage intermediate, which could combine or disproportionate.The reaction products from 5 indicate a radical chain oligomerization.The reaction of 8 gives an insoluble solid. o-Isotoluene (2) gives ene dimers.
- Gajewski, Joseph J.,Gortva, Andrea M.
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p. 373 - 378
(2007/10/02)
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- Carbocations as Electron Acceptors. Photoexcitation of the Charge-Transfer Complexes of Tropylium Salts and Aromatic Hydrocarbons
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Tropylium cation (C7H7+) forms electron donor-acceptor or EDA complexes with various benzene, naphthalene, and anthracene donors (Ar), as evidenced by the series of brightly colored solutions showing absorption bands that vary with the arene ionization potentials according to Mulliken charge-transfer theory.The spectrophotometric measurement of the formation constants indicates the presence of uniformly weak (1:1) complexes +> with K-1 in acetonitrile.However, the successful isolation of single crystals of the unique cationic EDA complex allows X-ray crystallography to establish the charge-transfer (CT) transition as deriving from centrosymmetric layered structures of tropylium-naphthalene pairs at interannular separations of 3.3 Angstroem.The direct correspondence of such solid-state structures with the tropylium EDA complexes in solution is demonstrated by an excellent correlation of the relevant CT energies (hνCT) obtained from the reflectance and absorption spectra, respectively.Time-resolved spectroscopy following the 532-nm irradiation of the tropylium EDA complex in acetonitrile with a 30-ps laser pulse leads to the resolved picosecond absorption spectra of arene cation radicals within the CT excited (ion-radical pair) state as .+, C7H7.>.The temporal evolution of the transient Ar.+ absorbance with first-order rate constants of k1>=4 x 1E10s-1 for various anthracenes relates to the back-electron-transfer from this ion-radical pair on its return to the original ground-state EDA complex.Such a facile annihilation of the solvent-caged ion-radical pair limits the photochemistry of tropylium EDA complexes to electron donors such as dianthracene and hexamethyl(Dewar benzene) in which the cation radical is highly labile.Thus, the brief lifetime of Ar.+ with τ ca. 15 ps largely precludes second-order quenching processes.
- Takahashi, Y.,Sankararaman, S.,Kochi, J.K.
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p. 2954 - 2967
(2007/10/02)
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