- New chiral 1,2-aminoalcohols derived from biomass and their application in diethyl zinc additions
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A convenient procedure for the preparation of chiral 1,2-aminoalcohols starting from levoglucosenone, a biomass derivative, is described. The 1,2-aminoalcohols, bearing primary, secondary, and tertiary amino groups, were tested as chiral catalysts in the
- Zanardi, María M.,Botta, María C.,Suárez, Alejandra G.
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- Naphthopyrans and their C4 alcohols by cyclization of substituted naphthalenes using potassium t-butoxide in dimethylformamide. generality and stereochemical, including conformational, effects
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The generality of the high-yielding, stereoselective cyclization of 2-allyl-3-(1?-hydroxyethyl)-1,4-dimethoxynaphthalene 1 to afford trans-3,4-dihydro-5,10-dimethoxy-1,3-dimethylnaphtho[2,3-c]pyran 2 is investigated by replacing each of the methoxy groups in the substrate by an ethyl substituent and subjecting these to cyclization reaction conditions identical to those originally reported. For shorter reaction times with potassium tert-butoxide in dimethylformamide under nitrogen, the derived 1-ethyl-, 4-ethyl-, and 1,4-diethylnaphthalenes all cyclize to the trans-1,3-dimethyl compounds, whereas longer times yield increasing proportions of the corresponding cis-isomers. Under air, the epimeric C4 alcohols rel-(1R,3R,4S)-3,4-dihydro-5-ethyl-4-hydroxy-10-methoxy-1,3-dimethylnaphtho[2, 3-c]pyran 50 and its rel-(1R,3R,4R) isomer 51 are also isolated from 2-allyl-1-ethyl-3-(1?-hydroxyethyl)-4-methoxynaphthalene 11. The half-chair conformation of pyran 50 is inverted relative to that of its C4 epimer 51. CSIRO 2007.
- Giles, Robin G. F.,Green, Ivan R.,Swigelaar, Wendell P.,Taylor, C. Peter
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- Isolation of a hydrogen-bonded complex based on the anthranol/anthroxyl pair: Formation of a hydrogen-atom self-exchange system
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A hydrogen-bonded complex was successfully isolated as crystals from the anthranol/anthroxyl pair in the self-exchange proton-coupled electron transfer (PCET) reaction. The anthroxyl radical was stabilized by the introduction of a 9-anthryl group at the carbon atom at the 10-position. The hydrogen-bonded complex with anthranol self-assembled by π-π stacking to form a one-dimensional chain in the crystal. The conformation around the hydrogen bond was similar to that of the theoretically predicted PCET activated complex of the phenol/phenoxyl pair. X-ray crystal analyses revealed the self-exchange of a hydrogen atom via the hydrogen bond, indicating the activation of the self-exchange PCET reaction between anthranol and anthroxyl. Magnetic measurements revealed that magnetic ordering inside the one-dimensional chain caused the inactivation of the self-exchange reaction.
- Hirao, Yasukazu,Saito, Tohru,Kurata, Hiroyuki,Kubo, Takashi
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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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- Magnetic substance and magnetic substance manufacturing method
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[object] A magnetization technique that enhances magnetic properties of an organic compound is provided without damaging properties of the organic compound or while maintaining the structure of the organic compound. [solution] The present disclosure is a method for manufacturing a magnetic substance composed of crystals of a magnetization target compound and an electron acceptor by combining the magnetization target compound with the electron acceptor; forming a solution by dissolving a mixture of the magnetization target compound and the electron acceptor in a solvent; maintaining the solution in a very low temperature state and allowing the solution to deposit the crystals of the magnetic target compound and the electron acceptor; and separating the crystals from the solvent.
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Page/Page column 17; 18
(2017/11/01)
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- A Photo-Triggered Traceless Staudinger–Bertozzi Ligation Reaction
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The use of light to control the course of a chemical/biochemical reaction is an attractive idea because of its ease of administration with high precision and fine spatial resolution. Staudinger ligation is one of the commonly adopted conjugation processes that involve a spontaneous reaction between azides and arylphosphines to form iminophosphoranes, which further hydrolyze to give stable amides. We designed an anthracenylmethyl diphenylphosphinothioester (1) that showed promising Staudinger ligation reactivity upon photo-excitation. Broadband photolysis at 360–400 nm in aqueous organic solvents induced heterolytic cleavage of its anthracenylmethyl–phosphorus bond, releasing a diphenylphosphinothioester (2) as an efficient traceless Staudinger–Bertozzi ligation reagent. The quantum yield of such a photo-induced heterolytic bond-cleavage at the optimal wavelength of photolysis (376 nm) at room temperature is ≥0.07. This work demonstrated the feasibility of photocaging arylphosphines to realize the photo-triggering of the Staudinger ligation reaction.
- Hu, Peng,Feng, Tianshi,Yeung, Chi-Chung,Koo, Chi-Kin,Lau, Kai-Chung,Lam, Michael H. W.
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supporting information
p. 11537 - 11542
(2016/08/05)
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- Trideuteriomethoxylation of aryl and heteroaryl halides
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Direct access to trideuteriomethoxylated aromatic and heteroaromatic compounds has been developed. Various aryl and heteroaryl halides underwent d3-methoxylation under mild reaction conditions by using a catalyst system composed of the commercially available monodentate phosphane ligand tBuXPhos and Pd(OAc)2. Inexpensive CD3OD served as an efficient trideuteriomethoxylating agent. The simple and straightforward synthesis of labeled methyl (hetero)aryl ethers via palladium-catalyzed C-O cross-coupling reaction of (hetero)aryl halides with CD3OD was developed. The tBuXPhos ligand is used for the first time in ether synthesis. Copyright
- Dash, Pragyanditi,Janni, Manojkumar,Peruncheralathan, S.
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supporting information
p. 4914 - 4917,4
(2012/12/12)
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- Trideuteriomethoxylation of aryl and heteroaryl halides
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Direct access to trideuteriomethoxylated aromatic and heteroaromatic compounds has been developed. Various aryl and heteroaryl halides underwent d3-methoxylation under mild reaction conditions by using a catalyst system composed of the commercially available monodentate phosphane ligand tBuXPhos and Pd(OAc)2. Inexpensive CD3OD served as an efficient trideuteriomethoxylating agent. The simple and straightforward synthesis of labeled methyl (hetero)aryl ethers via palladium-catalyzed C-O cross-coupling reaction of (hetero)aryl halides with CD3OD was developed. The tBuXPhos ligand is used for the first time in ether synthesis. Copyright
- Dash, Pragyanditi,Janni, Manojkumar,Peruncheralathan
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supporting information
p. 4914 - 4917
(2013/01/14)
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- Synthesis of 9-anthryl ethers from trans-9,10-dihydro-9,10- dimethoxyanthracene by acid-catalyzed transetherification
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During a study of electrophilic aromatic addition reactions (Ad EAr) to anthracene, anthryl ethers at the C9-position of anthracene were obtained as the major products when trans-9,10-dihydro-9,10- dimethoxyanthracene was reacted (10 minutes at
- Keun, Sam Jang,Hee, Young Shin,Dae, Yoon Chi
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experimental part
p. 1703 - 1707
(2009/12/24)
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- Electrophilic aromatic addition reaction (AdEAr) to anthracene
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After finding in a previous study that naphthalene and quinoline can react via electrophilic aromatic addition reaction (AdEAr), we applied this to anthracene. When anthracene was reacted with bromine in methanol in the presence of NaHCO3 and pyridine, 9,10-dihydro-9,10-dimethoxyanthracene (2) was obtained in 82% yield in the absence of substitution products or oxidative demethylation products like anthraquinone. The same reaction in ethanol produced 9,10-diethoxy-9,10-dihydroanthracene (9) in much lower yield (45%). In addition, we investigated the reactivity of addition product 2. Treatment of 2 with DDQ in benzene at 65 °C for 12 h produced 9,10-dimethoxyanthracene (3) in 62% yield, and 2 was rapidly transformed to 9-methoxyanthracene (4) in methanolic NaOH in 10 min. Moreover, the acid-catalyzed aromatization of 2 in 1-propanol at 75 °C for 10 min gave 9-n-propoxyanthracene (8) in 65% yield.
- Jang, Keun Sam,Shin, Hee Young,Chi, Dae Yoon
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p. 5666 - 5671
(2008/09/21)
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- Regioselective alkylation of anthrone, 5,5-dimethyl-3-isoxazolidinone and 4-methylquinolone by phase transfer catalysis
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Anthrone (1) can be alkylated selectively to give O-, C,O- or C,C-substituted compounds 2, 4, or 5, respectively. Similarly, 5,5-dimethyl-3-isoxazolidinone (6) and 4-methylquinolone (9) yield N- or O-derivatives 7 and 8 or 10 and 11, respectively. The product ratios can be influenced strongly sometimes by use of different phase transfer catalysts, but the sensitivity of each reaction towards the catalysts is unique.
- Dehmlow, Eckehard Volker,Bollhoefer, Joerg,Thye, Gorden
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p. 113 - 115
(2007/10/03)
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- Thermolabile Hydrocarbons, 34. - Thermal Stability of 9,9'-Bixanthene and 9,9',10,10'-Tetrahydro-10,10,10',10'-tetramethyl-9,9'-bianthracene. - Stabilisation Energies of Planar Benzhydryl Radicals
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The thermal cleavage of the central CC bonds in the title compounds was investigated.The activation parameters were obtained from kinetics and the equilibrium enthalpies and entropies from the temperature dependence of the equilibrium radical concentrations, determined by quantitative ESR. ΔH(excit.) and ΔHDiss are nearly identical but not ΔS(excit.) and ΔSDiss, as expected.The radical stabilisation enthalpies RSE obtained from these data (RSE: 7a = 17.9+/-1.3; 7b = 15.6+/-1.4 kcal/mol) correspond closely to twice the RSE of α-phenylethyl radicals (8.0+/-1.5 kcal/mol) determined previously.The smaller RSE of the benzhydryl radical (12.9+/-0.9 kcal/mol), therefore, must be due to its nonplanarity. - Key Words: C-C Bond cleavage, energetics and kinetics of / Radicals, stability of / ESR
- Herberg, Clemens,Beckhaus, Hans-Dieter,Ruechardt, Christoph
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p. 2065 - 2072
(2007/10/02)
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- Oxidation of 10-methoxy-9-anthraldehyde with various oxidising agents in protic and aprotic media
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Treatment of 10-methoxy-9-anthraldehyde (5) with various oxidising agents in protic and aprotic media fails to produce 10-methoxy-9-anthranoic acid (4), instead 9,10-anthraquinone is obtained in most cases.The effect of acid/alkali on 5 itself also gives rise to 9,10-anthraquinone and a trace of anthrone.Attempted decarbonylation of 9-methoxyanthracene-10-ketocarboxylic acid (7) fails to give the desired 4.
- Sen, P. K.,Lahiri, Sikha,Chattopadhyay, Gautam,Mandal, Dipak K.
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p. 978 - 979
(2007/10/02)
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- Application of Lanthanoids to Organic Chemistry. Direct Alkoxylation of Anthracene
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Direct alkoxylation of anthracene with some lower alcohols and ethylene glycol monoalkyl ethers, or monoacetate were carried out in the presence of cerium(IV)tetrakis(trifluoro acetate), and expected alkoxylated anthracene derivatives were obtained.
- Sugiyama, Takashi
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p. 1013 - 1016
(2007/10/02)
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- Cycloreversion Induced by Charge-Transfer Excitation of Electron Donor-Acceptor Complexes. Wavelength-Dependent Photochemistry of Dianthracene
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The electron donor-acceptor or EDA complexes of dianthracene (An2 is the ?-dimer of anthracene) and its derivatives with tetracyanoethylene show two unusually well-resolved charge-transfer (CT) bands.Specific irradiation of each of these absorption bands with monochromatic light at five selected wavelengths ranging from 405 to 577 nm leads to the clean cycloreversion of An2 to anthracene.The striking wavelength-dependent quantum efficiency for cycloreversion is analyzed in terms of two different CT ion pairs derived from the photoexcitation of the first and second absorption bands, which correspond to electron promotion from the HOMO and SHOMO (second highest occupied molecular orbital) of the dianthracene donor, respectively.Orbital correlations between dianthracene ?-dimer reveal that electron promotion from the SHOMO of dianthracene leads to an excited radical ion An2(+) which is more dissociative than that derived from the HOMO transition.
- Masnovi, J. M.,Kochi, J. K.
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p. 6781 - 6788
(2007/10/02)
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- COMPETITION ENTRE SUBSTITUTION NULCEOPHILE ET REDUCTION CHEZ LES BROMO-9 ANTHRACENES DANS L'ACTION DES ANIONS PHENATE ET METHYLATE; APPLICATION A LA MONO-DEUTERIATION SPECIFIQUE EN MESO EN SERIE ANTHRACENIQUE
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Treatment of meso-substituted 9-bromoanthracenes bearing no hydrogen in the α position with potassium phenoxide in DMF gives rise to a competition between nucleophilic substitution and reductive dehalogenation.Derivatives carrying electron attracting groups, 1c (Br), 1e (CN) and 1f (NO2), react essentially by substitution leading to phenolic ethers 2, whereas with non-activated bromides, 1a (H), 1b (C6H5) and 1d (OC6H5), the main reaction is a reduction to anthracenes 3 which should arise from an electron transfer.A reduction of 9-bromoanthracene into anthracene is also observed with sodium methoxide and it is shown, by labelling, that this one must result from a hydride transfer from methoxide.It may be applied to the specific meso-monodeuterization of various anthracenic derivatives.
- Rigaudy, J.,Seuleiman, A.M.,Cuong, Nguyen Kim
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p. 3157 - 3162
(2007/10/02)
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