- Generation and Reactivity Studies of Diarylmethyl Radical Pairs in Crystalline Tetraarylacetones via Laser Flash Photolysis Using Nanocrystalline Suspensions
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The nanosecond electronic spectra and kinetics of the radical pairs from various crystalline tetraarylacetones were obtained using transmission laser flash photolysis methods by taking advantage of aqueous nanocrystalline suspensions in the presence of su
- Park, Jin H.,Hughs, Melissa,Chung, Tim S.,Ayitou, A. Jean-Luc,Breslin, Vanessa M.,Garcia-Garibay, Miguel A.
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supporting information
p. 13312 - 13317
(2017/10/05)
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- Palladium-catalyzed reaction of 2-hydroxy-2-methylpropiophenone with aryl bromides: A unique multiple arylation via successive C-C and C-H bond cleavages
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2-Hydroxy-2-methylpropiophenone undergoes a unique multiple arylation via C-C and C-H bond cleavages upon treatment with excess aryl bromides in the presence of a palladium catalyst to give 1,1,2,2-tetraarylethanes and 4,4-diaryl-1-phenylisochroman-3-ones. Copyright
- Wakui, Hiroyuki,Kawasaki, Satoshi,Satoh, Tetsuya,Miura, Masahiro,Nomura, Masakatsu
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p. 8658 - 8659
(2007/10/03)
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- Ruthenium-catalyzed carbon-carbon formation to synthesize tetraarylethanes and tetraarylxylylene through dechlorinative dimeric reaction
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Dechlorinative coupling-dimerization reaction is studied to synthesize alkanes by using tris-triphenylphosphine ruthenium (II) in the presence of hydrogen atmosphere. Two types of halides (α-chlorodiarylmethanes 1a-d and bis(chlorophenylmethyl)-1, 3-phenylene 6) are employed as substrates to form radical species and then dimerized to generate alkanes in high yields. To our knowledge, it is the first time that the formation of 1,1,2,2-tetraarylethanes and 1,2,9,10-tetraphenyl-di- m -xylylene over typical ruthenium-catalyzed dehalogenative coupling-dimerization conditions is reported.
- Li, Yanjun,Kijima, Tatsuro,Izumi, Taeko
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- Structural requirements for decarbonylative α,α-diarylation reaction of 2-methoxyalkanoic acids in phosphorus pentoxide-methanesulfonic acid mixture yielding 1,1-diarylalkane homologs
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2-Methoxyalkanoic acids were found to undergo consecutive decarbonylative α,α-diarylation in P2O5-MsOH instead of Friedel-Crafts type arylation on the carbonyl carbon. The influence of the substituents of the arenes and the carboxylic acids in this reaction was elucidated based on the reaction yields. The reaction behavior was found to be primarily governed by the electron-withdrawing/releasing property of the α-substituents on the carboxylic acids as well as the positive species-accepting ability of the arenes. The steric hindrance was shown to participate in determining the reaction feasibility as a secondary factor.
- Yonezawa, Noriyuki,Hino, Tetsuo,Tokita, Yoshimi,Matsuda, Kazuhisa,Ikeda, Tomiki
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p. 14287 - 14296
(2007/10/03)
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- Efficient hydrogenation of sterically hindered olefins with borane-methyl sulfide complex
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Sterically hindered olefins are efficiently reduced to the corresponding alkanes by the boranemethyl sulfide (BMS) complex at room temperature (or below) in dichloromethane containing a mild one-electron oxidant (such as an aromatic cation radical) or by the passage of an anodic current. In an alternative procedure, the hydrogenation of the same (electron-rich) olefins with the BMS complex (in the absence of a one-electron oxidant) is also carried out in the presence of a strong Bronsted acid (such as HBF4). In the oxidative activation, olefin cation radicals are the first observable intermediates, and separate experiments (including transient electrochemistry) confirm the facile reduction of the olefin cation radical by borane to produce the corresponding alkane. The direct protonation of olefins produces carbocationic intermediates which are also efficiently reduced by borane to the corresponding alkanes. The intermediacy of both olefin cation radicals and carbocations in the hydrogenation procedure with borane is discussed.
- Rathore,Weigand,Kochi
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p. 5246 - 5256
(2007/10/03)
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- Transformation of Carbinols by RuCl2(PPh3)3 and by Some Other Transition-Metal Catalysts
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Several platinoid metal catalysts have been shown to promote reductive coupling, dehydration, disproportionation, and dehydrogenation of diarylcarbinols.Mechanistic studies were performed at 180-210 deg C with benzhydrol as substrate and RuCl2(PPh3)3 as catalyst.In aromatic hydrocarbon solvents the main process is reductive coupling.In this medium solvated RuCl2(PPh3)2 is suggested to be the active catalyst.In dimethyl sulfoxide the starting complex is transformed initially into RuCl2(PPh3)(Me2SO)2 and causes chiefly carbinol dehydrogenation.Ruthenium alkoxides are implied as common reaction intermediates in all four catalyses.Ruthenium hydrides are suggested to take part in the reductive coupling, disproportionation, and dehydrogenation processes.Some aliphatic and primary aromatic alcohols that do not react by themselves in the presence of RuCl2(PPh3)3 can both serve as active hydrogen donors and form crossover products in the presence of secondary and tertiary aromatic carbinols.
- Pri-Bar, Ilan,Buchman, Ouri,Schumann, Hebert,Kroth, Heinz J.,Blum, Jochanan
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p. 4418 - 4428
(2007/10/02)
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