486-25-9Relevant articles and documents
Lobanova, I. A.,Zdanovich, V. I.,Petrovskii, P. V.,Vasyukova, N. I.,Kolobova, N. E.
, (1987)
Denney,Klemchuk
, p. 6014 (1958)
Fulvalene Derivatives Containing a Tetrabenzofluorene Unit: New Nonplanar Fulvalenes with High Electron Affinity
Yamada, Kenta,Shibamoto, Hiroshi,Tanigawa, Yusuke,Ishikawa, Hiroyuki,Nishida, Jun-Ichi,Kitamura, Chitoshi,Kurata, Hiroyuki,Kawase, Takeshi
, p. 2085 - 2090 (2016)
17H-Tetrabenzo[a,c,g,i]fluoren-17-one possessing a nonplanar, helicene-like structure was efficiently prepared by aerial oxidation of 17H-tetrabenzo[a,c,g,i]fluorene under mild basic conditions. A quinone methide and an unsymmetrical fulvalene containing a tetrabenzofluorene unit were synthesized from the ketone. Treatment of 17-bromotetrabenzo[a,c,g,i]fluorene with a base afforded a symmetric fulvalene as an air-sensitive blue solid. Electrochemical analyses revealed that these compounds have high electron affinities.
Lobanova, I. A.,Batsanov, A. S.,Zdanovich, V. I.,Struchkov, Yu. T.,Kolobova, N. E.
, (1988)
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Schiessler,Eldred
, p. 3958 (1948)
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Chromium-assisted oxidations with sodium perborate by phase transfer catalysis
Muzart,N'Ait Ajjou
, p. 575 - 580 (1991)
Oxidation by sodium perborate of selected alcohols and unsaturated compounds to ketones and acids was achieved at 60-80°C in the presence of catalytic amounts of chromium(VI) oxide and methyltridecylammonium chloride.
Retro Abramov vs. Rearrangement path competition in hydroxyphosphonate decomposition
Gancarz, Roman,Gancarz, Irena,Deron, Agnieszka
, p. 61 - 69 (2000)
1-hydoxyphosphonates in the presence of aliphatic amine undergo two competitive processes: retro Abramov reaction and intramolecular hydroxyphosphonate-phosphate rearrangement. Both reaction rates and their ratio strongly depend on the nature of the substituent on a alpha carbon atom. Kinetic experiments indicate that two reactions proceed via common transition state.
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Wade et al.
, p. 3724 (1979)
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Huntress,Hershberg,Cliff
, p. 2720,2724 (1931)
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On the mechanism of the directed ortho and remote metalation reactions of N,N-dialkylbiphenyl 2-carboxamides
Tilly, David,Fu, Jian-Min,Zhao, Bao-Ping,Alessi, Manlio,Castanet, Anne-Sophie,Snieckus, Victor,Mortier, Jacques
, p. 68 - 71 (2010)
"Chemical Equation Presented" A study concerning the mechanism of the LDA-mediated ortho and remote metalation of N,N-dialkyl-2-biphenyl carboxamides (e.g., 4a) is reported. On the basis of site-selective lithiation/electrophile quench experiments, including deuteration, the LDA metalation of 4 is proposed to involve initial amide-base complexation (CIPE) and equilibrium formation of 5, whose fast reaction with an in situ electrophile (TMSCI) to afford 6 prevents its equilibration with 7. In the absence of an electrophile,5 undergoes equilibration via 4a with 7, whose fate is instantaneous cyclization to a stable tetrahedral carbinolamine oxide 8 which, only upon hydrolysis, affords fluorenone (3).
C-OH bond cleavage initiated by electron transfer: Electroreduction of 9-fluorenol
Mendkovich, Andrey S.,Syroeshkin, Mikhail A.,Nasybullina, Darya V.,Mikhailov, Mikhail N.,Gultyai, Vadim P.,Elinson, Mikhail N.,Rusakov, Alexander I.
, p. 962 - 973 (2016)
Cyclic voltammetry, chronoamperometry, coulometry, electrolysis, digital simulation, quantum chemical calculations of 9-fluorenol as an example, were used to show that the electroreduction of aryl derivatives of methanol in 0.1 M Bu4NClO4/DMF proceeds via the ECE mechanism (including the stages of radical anion formation and the C-OH bond cleavage in the radical anion) complicated by the reactions of the depolarizer with the anionic products. Among these reactions are the deprotonation of 9-fluorenol and its monoanions by hydroxide anion and fluorenyl anion. The thermodynamic parameters of the reactions have been estimated both theoretically and experimentally. It was found that the equilibrium constants of the fluorenyl anions deprotonation are close (C-anion) or higher (O-anion) than that of fluorenol. As a result the total equilibrium is shifted towards the side of the dianion of 9-fluorenone. The unusual ratio of the equilibrium constants was explained by lower basicity of π?-dianion compare with other anions.
Selective Oxidation of Arenes in Dry Media under Focused Microwaves
Oussaid, Abdelouahad,Loupy, Andre
, p. 342 - 343 (1997)
Arenes are oxidized into ketones within 10-30 min using KMnO4 impregnated on alumina under microwave activation in dry media, instead of several days under classical conditions.
Huurdeman et al.
, p. 3449 (1971)
Oxidative carbonylation of aromatic hydrocarbons in the system containing Pd or Rh compound, trifluoroacetic acid and its anhydride, and MnO2 or Mn2O3
Kalinovskii,Pogorelov,Gelbshtein,Akhmetov
, p. 1457 - 1462 (2001)
Manganese(II) and manganese(IV) oxides are effective oxidants for the reaction of oxidative carbonylation of aromatic hydrocarbons proceeding at 0.1-1.5 MPa of CO and 20-100°C in trifluoroacetic acid and its anhydride and catalysed by Pd and Rh compounds. Under these conditions up to 9000 moles of aromatic acid is formed per 1 g-at of platinum. With rhodium catalyst instead of the palladium in the case of toluene content of p-toluic acid in the target product increases from 50 to 90%. Carbonylation of biphenyl at 0.1 MPa of CO and 20°C leads toformation of about 15% of fluorenone together with 4-phenylbenzoic acid (60%).
Surface-inspired molecular vanadium oxide catalysts for the oxidative dehydrogenation of alcohols: Evidence for metal cooperation and peroxide intermediates
Werncke, C. Gunnar,Limberg, Christian,Knispel, Christina,Mebs, Stefan
, p. 12129 - 12135 (2011)
On the basis that thiacalix[4]arene (H4T4A) complex (PPh 4)2[H2T4A(VO2)]2 (Ia) was found to be an adequate functional model for surface species occurring on vanadium oxide based catalysts and itself catalyses the oxidative dehydrogenation (ODH) of alcohols, an analogue containing 2,2′-thiobis(2, 4-di-tert-butylphenolate), SL2-, as ligand, namely, (PPh4)2[SLVO2]2 (II) was investigated in the same context. Despite the apparent similarity of Ia and II, studies on II revealed several novel insights, which are also valuable in connection with surfaces of vanadia catalysts: 1) For Ia and II similar turnover numbers (TONs) were found for the ODH of activated alcohols, which indicates that the additional OH units inherent to Ia do not contribute particularly to the activity of this complex, for instance, through prebinding of the alcohol. 2) On dissolution II enters into an equilibrium with a monomeric form, which is the predominant species in solution; nevertheless, ODH proceeds exclusively at the dimeric form, and this stresses the need for cooperation of two vanadium centres. 3) By omitting O2 from the system during the oxidation of 9-fluorenol, the reduced form of the catalyst could be isolated and fully characterised (including single-crystal X-ray analysis). The corresponding intermediate had been elusive in case of thiacalixarene system Ia. 4) Reoxidation was found to proceed via a peroxide intermediate that also oxidises one alcohol equivalent. As the peroxide can also perform mono- and dioxygenation of the thioether group in II, after a number of turnovers the active catalyst contains a sulfone group. The reduced form of this ultimate catalyst was also isolated and structurally characterised. Possible implications of 1)-4) for the function of heterogeneous vanadia catalysts are discussed.
Substitution of 9-(α-bromo-α-arylmethylene)fluorenes by thiolate ions in aqueous acetonitrile
Rappoport, Zvi,Shainyan, Bagrat A.
, p. 871 - 878 (1997)
The substitution of 9-(α-bromo-α-arylmethylene)fluorenes by MeS- and p-TolS- ions in 80% MeCN-20% H2O is a second-order reaction. With MeS- ,for the change of the α-aryl group, Hammett's p=l.07 in MeCN. The reaction rate decreases on increasing the water content of the medium. The reactions proceed by the AdN-￡ route and no competitive SN1 reaction was observed. The expected influence of the changes in the substituent, solvent, nucleophile and nucleofuge on the competition between the AdN-E and SN1 reactions was analyzed.
Indolopyridines with a bridging heteroatom. 9. Synthesis, structure, and thermolysis of 5-hydroxy-5-(2-pyridyl)-fluorene and -4-azafluorene
Soldatenkov,Kolyadina,Kuleshova,Khrustalev
, p. 817 - 821 (1996)
Treatment of fluorenone or 4-azafluoren-9-one with 2-pyridyllithium gives 5-hydroxy-5-(2-pyridyl)fluorene and its aza analog. The structure of the former has been studied by x-ray crystallography. It was found that, in contrast to the non-condensed diaryl-2-pyridylcarbinols, these alcohols do not undergo acid catalyzed dehydration and heterocyclization. Under pyrolytic conditions, 5-pyridylfluorenol undergoes fission to form fluorenone. 1997 Plenum Publishing Corporation.
Prinzbach,H.,Fischer,U.
, p. 1692 - 1722 (1967)
Shirafuji et al.
, p. 2249 (1973)
Direct proof for a lower reactivity of monomeric vs. dimeric oxidovanadium complexes in alcohol oxidation
Werncke, C. Gunnar,Limberg, Christian,Metzinger, Ramona
, p. 2426 - 2432 (2013)
Previous attempts to synthesize and isolate (thiobisphenolate) vanadium(V) dioxido complexes had always provided their dimers containing [O=V(μ-O) 2V=O]2+ cores, and these also dominate the solution reactivity. Hence, the behavior of their parent monomers, which represent the major species in solution, has remained uncertain. Herein we report the development of a synthetic route that allowed for the successful isolation, spectroscopic investigation, and structural characterization of the monomer PPh4[SLVO2] (3) [SL2- = 2′2-thiobis(2, 4-di-tert-butylphenolate)]. For this purpose PPh 4[SLVOCl2] (1) had to be accessed first in order to convert it to the ethoxido compound PPh4[ SLVO(OEt)2] (2), which is more prone to hydrolysis. Treatment of 2 with stoichiometric amounts of water followed by immediate cooling to -30°C led to crystals of 3. After its dissolution NMR spectra were recorded that were identical with those obtained after dissolution of its dimer, thus confirming the monomer/dimer equilibrium postulated previously. The molecular structure of 3 revealed the absence of a V···S interaction, which, however, stabilizes its dimer, and thus suggested the employment of a bisphenolate ligand lacking a bridging sulfur atom to obtain an analogue, which does not undergo dimerization in solution. In EtL2- the sulfur atom is replaced by an ethylmethine unit and indeed the corresponding complex NBu4[EtLVO 2] (4) proved to be stable as a monomer. Investigation of its potential as a catalyst for the oxidative dehydrogenation of 9-fluorenol confirmed a much lower reactivity in comparison to dimeric complexes, which is discussed. Copyright
Chardonnens et al.
, p. 3044,3048 (1973)
Ray,Geiser
, p. 200 (1949)
Synthesis of Substituted Quinazolin-4(3H)-imines from Aryldiazonium Salts, Nitriles and 2-Cyanoanilines via A Metal-Free Tandem Approach
Ramanathan, Mani,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
, p. 5840 - 5843 (2017)
A transition metal-free synthesis of multisubstituted quinazolin-4(3H)-imines has been realized by the direct reaction of aryldiazonium salts, nitriles, and 2-cyanoanilines in a one-pot fashion. This strategy utilizes the in situ formation of reactive N-arylnitrilium intermediate, which undergoes further tandem cyclization with consecutive formation of N-C bonds. Broad functional group compatibility, mild conditions, shorter time, and operational simplicity are the notable features of this report.
Selective Aerobic Oxidation of Csp3-H Bonds Catalyzed by Yeast-Derived Nitrogen, Phosphorus, and Oxygen Codoped Carbon Materials
Ju, Zhao-Yang,Song, Li-Na,Chong, Ming-Ben,Cheng, Dang-Guo,Hou, Yang,Zhang, Xi-Ming,Zhang, Qing-Hua,Ren, Lan-Hui
supporting information, p. 3978 - 3988 (2022/03/16)
Nitrogen, phosphorus, and oxygen codoped carbon catalysts were successfully synthesized using dried yeast powder as a pyrolysis precursor. The yeast-derived heteroatom-doped carbon (yeast@C) catalysts exhibited outstanding performance in the oxidation of Csp3-H bonds to ketones and esters, giving excellent product yields (of up to 98% yield) without organic solvents at low O2pressure (0.1 MPa). The catalytic oxidation protocol exhibited a broad range of substrates (38 examples) with good functional group tolerance, excellent regioselectivity, and synthetic utility. The yeast-derived heteroatom-doped carbon catalysts showed good reusability and stability after recycling six times without any significant loss of activity. Experimental results and DFT calculations proved the important role of N-oxide (N+-O-) on the surface of yeast@C and a reasonable carbon radical mechanism.
Gold complexes of bis-indazole-derived N-Heterocyclic carbene: Synthesis, structural characterizations, and catalysis
Zhang, Hua,Xu, Ting,Li, Dongdong,Cheng, Tao,Chen, Jing,Zhou, Yang
, (2021/02/26)
A novel series of bis Indy-NHC gold complexes have been developed and investigated via a mild Ag-carbene transfer route. The obtained complexes were characterized by NMR spectroscopy and X-ray diffraction analysis. The catalytic property of these gold complexes was further evaluated in the oxidation of benzylic. The gold complex E1 showed a high catalytic activity in the oxidation of various benzylic substrates, resulting in the corresponding carbonyl compounds with excellent yields using TBHP as oxidant.
Integration of Earth-Abundant Photosensitizers and Catalysts in Metal-Organic Frameworks Enhances Photocatalytic Aerobic Oxidation
Feng, Xuanyu,Pi, Yunhong,Song, Yang,Xu, Ziwan,Li, Zhong,Lin, Wenbin
, p. 1024 - 1032 (2021/01/26)
We report here the construction of two metal-organic frameworks (MOFs), Zr6-Cu/Fe-1 and Zr6-Cu/Fe-2, by integrating earth-abundant cuprous photosensitizers (Cu-PSs) and Fe catalysts for photocatalytic aerobic oxidation. Site isolation and pore confinement stabilize both Cu-PSs and Fe catalysts, while the proximity between active centers facilitates electron and mass transfer. Upon visible light irradiation and using O2 as the only oxidant, Zr6-Cu/Fe-1 and Zr6-Cu/Fe-2 efficiently oxidize alcohols and benzylic compounds to afford corresponding carbonyl products with broad substrate scopes, high turnover numbers of up to 500 with a 9.4-fold enhancement over homogeneous analogues, and excellent recyclability in four consecutive runs. Control experiments, spectroscopic evidence, and computational studies revealed the photo-oxidation mechanism: Oxidative quenching of [Cu-PS]? by O2 affords [CuII-PS], which efficiently oxidizes FeIII-OH to generate a hydroxyl radical for substrate oxidation. This work highlights the potential of MOFs in promoting earth-abundant metal-based photocatalysis.
