- Generation of arylated quinones by iron-catalyzed oxidative arylation of phenols: Formal synthesis of phellodonin, sarcodonin ε, leucomelone and betulinan A
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Biologically and pharmaceutically relevant arylated quinones (Quin-Ar) have been synthesized via direct C-H arylation of a variety of phenols using arylboronic acids. An inexpensive, environmentally friendly iron catalyst, ferric sulphate, Fe2(SO4)3, was employed in this operationally simple and efficient method.
- Deb, Arghya,Agasti, Soumitra,Saboo, Tapish,Maiti, Debabrata
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supporting information
p. 705 - 710
(2014/04/03)
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- Palladium-catalyzed direct C-H functionalization of benzoquinone
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A direct Pd-catalyzed C-H functionalization of benzoquinone (BQ) can be controlled to give either mono- or disubstituted BQ, including the installation of two different groups in a one-pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cyclo-alkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents.
- Walker, Sarah E.,Jordan-Hore, James A.,Johnson, David G.,MacGregor, Stuart A.,Lee, Ai-Lan
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supporting information
p. 13876 - 13879
(2015/02/05)
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- The direct arylation of benzoquinones with arylboronic acid promoted by iron(II) oxalate
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Arylations of various quinones with several arylboronic acids have been developed. The reactions proceed readily at ambient temperature using iron(II) oxalate as a catalyst and potassium persulfate as a co-oxidant. The mechanism is presumed to proceed through a nucleophilic radical addition to the quinone with in situ reoxidation of the resulting dihydroquinone.
- Huanga, Yibo,Guanb, Dan
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p. 649 - 651
(2014/01/17)
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- FeSO4-promoted direct arylation of benzoquinones with ArB(OH)2 or ArBF3K
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FeSO4·7H2O was proven to work as effective promoter for the direct arylation of benzoquinones with aryl boronic acids in the presence of K2S2O8. In the arylation, slow addition of iron solution was crucial to efficiently proceed with the reaction. Interestingly, the Fe-mediated arylation could be converted into a catalytic reaction by using hydroquinones, instead of benzoquinones, or addition of ascorbic acid.
- Komeyama, Kimihiro,Kashihara, Tetsuya,Takaki, Ken
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supporting information
p. 1084 - 1086
(2013/04/10)
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- Iron-mediated direct arylation with arylboronic acids through an aryl radical transfer pathway
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A novel iron-mediated direct C-H arylation of quinones and pyridine analogues with arylboronic acids has been developed using dichloromethane and water as solvents at ambient temperature. FeS is employed and serves as an efficient catalyst. A detailed reaction mechanism is speculated and expounded.
- Wang, Jian,Wang, Shan,Wang, Gao,Zhang, Ji,Yu, Xiao-Qi
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supporting information
p. 11769 - 11771
(2013/01/15)
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- Reactive dyestuffs
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Triphendioxazine reactive dyestuffs of the general formula STR1 with the substituent definition given in the description, are outstandingly suitable for dyeing and printing materials containing hydroxyl groups or amide groups. They give red dyeings with high wet- and light-fastnesses.
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- Triphendioxazine dyestuffs
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Triphendioxazine dyestuffs of the formula STR1 having the substituent meanings specified in the descriptive part, are highly suitable for dyeing and printing hydroxyl- or amido-containing materials, in particular fibre materials, and produce wash-fast dyeings and prints.
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- Mechanism of the Oxidation of NADH by Quinones. Energetics of One-Electron and Hydride Routes
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The kinetics of NADH oxidation by 7 o-benzoquinones and 14 p-benzoquinones were studied by using buffered aqueous solutions and UV/vis spectroscopy.For each quinone the rate law was first order in NADH and first order in quinone.The rate constants varied from 0.0745 to 9220 M-1s-1.Variation of the pH from 6 to 8 gave no change in rate.The use of 4-D and 4,4-D2NADH revealed kinetic isotope effects.The dideutero data gave kH/kD in the range 1.6-3.1 for p-quinones and 4.2 for 3,5-di-tert-butyl-o-quinone.When p-quinones were used, the log k was a linear function of Eo for the quinone/hydroquinone monoanion (Q/QH(1-)) couple with a slope of 16.9 V-1. o-Quinones reacted about 100 times more rapidly, but the same linear relationship with a slope of 16.4 V-1 was observed.Comparisons to data for one-electron-transfer reactions indicate that such mechanisms are not involved.A hydride-transfer mechanism accommodates all the data, and rate-limiting hydrogen atom transfer followed by electron transfer cannot be ruled out.
- Carlson, Brian W.,Miller, Larry L.
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p. 479 - 485
(2007/10/02)
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