- Nondirecting Group sp3 C?H Activation for Synthesis of Bibenzyls via Homo-coupling as Catalyzed by Reduced Graphene Oxide Supported PtPd@Pt Porous Nanospheres
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The use of heterogeneous bimetallic Pd-based nanocatalyst for directing the inactivated sp3 C?H coupling has been scarcely explored. This work reported the formation of symmetrical C?C bonds from the inactivated sp3 C?H bonds catalyzed by employing reduced graphene oxide supported PtPd@Pt porous nanospheres. The reaction of sp3 C?H activation proceeded under mild conditions without any solvent, ligand or directing group. It is a higher atom-, step- and cost-effectiveness strategy for developing heterogeneous catalysts in the synthesis of bibenzyls with various functional groups (e. g. aryl, alkyl, methoxyl, halogen, ester, and pyridyl). (Figure presented.).
- Wang, Zheng-Jun,Lv, Jing-Jing,Yi, Rong-Nan,Xiao, Min,Feng, Jiu-Ju,Liang, Zhi-Wu,Wang, Ai-Jun,Xu, Xinhua
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- Vanadium(II) complexes as efficient reagents for direct construction of asymmetric quaternary carbons from carbonyl compounds
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Direct geminal diallylation of propiophenone with allyl bromide has been achieved in the presence of vanadium(II) species. By applying this method, direct construction of asymmetric quaternary carbons from propiophenone has been accomplished. Strong oxophilicity of the low-valent vanadium facilitated the deoxygenative reaction. The present reaction is characteristic of vanadium complexes.
- Kataoka, Yasutaka,Makihira, Isamu,Akiyama, Hiroaki,Tani, Kazuhide
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- Direct construction of quaternary carbons from carbonyl compounds utilizing low-valent vanadium complexes
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Direct geminal diallylation of a carbonyl compound with allyl bromide has been achieved in the presence of a low-valent vanadium complex and zinc. The diallylation has been found to proceed stepwise and the two allyl groups were introduced successively. By applying this method, one-pot synthesis of asymmetric quaternary carbons has been accomplished. As the first alkylating reagent a combination of allyl bromide and zinc, a Grignard reagent, or an alkyllithium can be used. The second one should be the combination of a low- valent vanadium(II) complex and allyl bromide, benzyl bromide, or propargyl bromide. Strong oxophilicity of the low-valent vanadium facilitated the deoxygenative allylation.
- Kataoka, Yasutaka,Makihira, Isamu,Akiyama, Hiroaki,Tani, Kazuhide
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- A Novel C-C Single-Bond Formation Accompanying C-O Bond Cleavage by Use of a Ketone, an Alkylating Reagent, and a Low-Valent Vanadium Complex in the Presence of a Catalytic Amount of Molecular Oxygen
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A C-C single-bond-forming reaction from ketones with accompanying C-O bond cleavage mediated by a RMgBr or RLi-vanadium(II)-O2 system has been accomplished. Different from conventional reductive coupling reactions of ketones such as the McMurry coupling, the present method forms a C-C single (instead of a double) bond and yields a product that contains components derived from the ketone and the alkylating reagent in a one-pot reaction. Collaboration of both a low-valent vanadium(II) species and a higher-valent vanadium species produced from vanadium(II) and a catalytic amount of O2 effects the abstraction of the oxygen atom from a C-O bond.
- Kataoka, Yasutaka,Akiyama, Hiroaki,Makihira, Isamu,Tani, Kazuhide
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- Method for synthesizing 1,2-diphenylethane derivative by catalyzing coupling of sp3C-H bond through graphene-loaded palladium/platinum
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The invention provides a novel method for catalyzing activation of an sp3C-H bond to build a 1,2-diphenylethane compound by developing a novel graphene-loaded bimetal palladium/platinum catalyst whichis simple, convenient and efficient, is free of guide groups and free of participation of solvents and can be reused, so as to increase the yield of the target product, simplify operation steps and improve an atom utilization ratio and the recovery of the catalyst. The invention provides an economical, efficient and green method for preparing the compound. The method has the main advantages thatexperiment operation is simple and convenient, guide groups are not needed, the participation of other solvents is not needed, and the catalyst can be repeatedly recycled.
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Paragraph 0025; 0026
(2018/07/15)
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- Dicyanobenzene sensitized carbon-carbon bond cleavage in methoxybicumenes. Products and mechanistic studies
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Radical cations of p-methoxy-p-X-bicumenes generated by ET to excited-state dicyanobenzene undergo rapid irreversible C-C bond scission giving cumyl cations and radicals. The photoefficiency of the process (Φ = 0.13 for X = MeO, Φ 0.005 for X = CN) and the fate of the radicals produced depends strongly on substitution.
- Maslak, Przemyslaw,Chapman Jr., William H.
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p. 2715 - 2724
(2007/10/02)
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- Thermolabile Hydrocarbons, XXII. Thermolysis of symm. Tetraalkyldiarylethanes and the Resonance Energy of α,α-Dialkylbenzyl Radicals
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The products and the activation parameters for the thermolysis reactions of the hydrocarbons 1 - 10 were determined.From correlations between ΔG% and the ground state strain Hsp or the change in strain during the dissociation process Dsp the steric acceleration of this reaction was analyzed quantitatively.A comparison of this analysis with a corresponding correlation for simple Cq - Cq alkanes results in a resonance energie of 8.4 +/- 1.1 kcal * mol-1 for α,α-dialkylbenzyl radicals.The origin of the appreciable variation of ΔS% in this series and for the poorer precision of ΔH% /Hsp correlations is discuss ed.
- Kratt, Guenter,Beckhaus, Hans-Dieter,Ruechardt, Christoph
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p. 1748 - 1764
(2007/10/02)
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- Thermolabile Hydrocarbons, XX. Synthesis, Structure, and Strain of Sym. Tetraalkyl-1,2-diarylethanes
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The syntheses of 18 1,1,2,2-tetraalkyl-1,2-diarylethanes 1 - 4 by dimerisation procedures starting with 10 - 13 are reported.In the absence of p-substituents X and with increasing alkyl side chains the α,p-dimers 6 or their aromatic counter parts 7 are obtained besides or instead of 1.The relationships between strain enthalpy Hs, bond lengths, bond angles, torsional angles, and rotational barrier are discussed on the basis of force field calculations.They are supported by two additional experimental structure determinations by X-ray diffraction.
- Kratt, Guenter,Beckhaus, Hans-Dieter,Lindner, Hans Joerg,Ruechardt, Christoph
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p. 3235 - 3263
(2007/10/02)
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- PHOTOCHEMICAL OXIDATION AND DIMERIZATION OF ALKYLBENZENES. SELECTIVE REACTIONS OF THE ALKYL SIDE GROUPS
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Irradiations of alkylbenzene compounds in an oxygen atmosphere result exclusively in oxidation reactions, while in a less oxidative environment dimerization processes predominate.Under all conditions studied, the reactions took place only at one benzyl position.
- Pasternak, Mordechai,Morduchowitz, Abraham
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p. 4275 - 4278
(2007/10/02)
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