- Photocatalytic C-H Amination of Aromatics Overcoming Redox Potential Limitations
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We report the photocatalytic C-H amination of aromatics overcoming redox potential limitations. Radical cations of aromatic compounds are generated photocatalytically using Ru(phen)3(PF6)2, which has a reduction potential at a high oxidation state (Ered(RuIII/RuII) = +1.37 V vs SCE) lower than the oxidation potentials of aromatic substrates (Eox = +1.65 to +2.27 V vs SCE). The radical cations are trapped with pyridine to give N-arylpyridinium ions, which were converted to aromatic amines.
- Ikarashi, Gun,Kano, Naokazu,Morofuji, Tatsuya
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supporting information
p. 2822 - 2827
(2020/04/16)
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- Site-selective arene C-H amination via photoredox catalysis
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Over the past several decades, organometallic cross-coupling chemistry has developed into one of the most reliable approaches to assemble complex aromatic compounds from preoxidized starting materials. More recently, transition metal-catalyzed carbon-hydrogen activation has circumvented the need for preoxidized starting materials, but this approach is limited by a lack of practical amination protocols. Here, we present a blueprint for aromatic carbon-hydrogen functionalization via photoredox catalysis and describe the utility of this strategy for arene amination. An organic photoredox-based catalyst system, consisting of an acridinium photooxidant and a nitroxyl radical, promotes site-selective amination of a variety of simple and complex aromatics with heteroaromatic azoles of interest in pharmaceutical research. We also describe the atom-economical use of ammonia to form anilines, without the need for prefunctionalization of the aromatic component.
- Romero, Nathan A.,Margrey, Kaila A.,Tay, Nicholas E.,Nicewicz, David A.
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p. 1326 - 1330
(2015/10/12)
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- Novel quinolinequinone antitumor agents: Structure-metabolism studies with NAD(P)H:quinone oxidoreductase (NQO1)
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A series of quinolinequinones bearing various substituents has been synthesized, and the effects of substituents on the metabolism of the quinones by recombinant human NAD(P)H:quinone oxidoreductase (hNQO1) was studied. A range of quinolinequinones were selected for study, and were specifically designed to probe the effects of aryl substituents at C-2. A range of 28 quinolinequinones 2-29 was prepared using three general strategies: the palladium(0) catalyzed coupling of 2-chloroquinolines, the classical Friedlaender synthesis and the double-Vilsmeier reaction of acetanilides. One example of an isoquinolinequinone 30 was also prepared, and the reduction potentials of the quinones were measured by cyclic voltammetry. For simple substituents R2 at the quinoline 2-position, the rates of quinone metabolism by hNQO1 decrease for R2=Cl>H~Me>Ph. For aromatic substituents, the rate of reduction decreases dramatically for R 2=Ph>1-naphthyl>2-naphthyl>4-biphenyl. Compounds containing a pyridine substituent are the best substrates, and the rates decrease as R 2=4-pyridyl>3-pyridyl>2-pyridyl>4-methyl-2-pyridyl>5- methyl-2-pyridyl. The toxicity toward human colon carcinoma cells with either no detectable activity (H596 or BE-WT) or high NQO1 activity (H460 or BE-NQ) was also studied in representative quinones. Quinones that are good substrates for hNQO1 are more toxic to the NQO1 containing or expressing cell lines (H460 and BE-NQ) than the NQO1 deficient cell lines (H596 and BE-WT).
- Fryatt, Tara,Pettersson, Hanna I.,Gardipee, Walter T.,Bray, Kurtis C.,Green, Stephen J.,Slawin, Alexandra M. Z.,Beall, Howard D.,Moody, Christopher J.
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p. 1667 - 1687
(2007/10/03)
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- Novel quinolinequinone antitumor agents: Structure-metabolism studies with NAD(P)H:quinone oxidoreductase (NQO1)
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The effects of functional group changes on the metabolism of novel quinolinequinones by recombinant human NAD(P)H:quinone oxidoreductase (NQO1) are described. Overall, the quinolinequinones were much better substrates for NQO1 than analogous indolequinones, with compounds containing heterocyclic substituents at C-2 being among the best substrates.
- Fryatt, Tara,Goroski, Dean T.,Nilson, Zachary D.,Moody, Christopher J.,Beall, Howard D.
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p. 2195 - 2198
(2007/10/03)
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- 4-aryl-3-(heteroarylureido)quinoline derivatves
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Compounds of the formula STR1 and the pharmaceutically acceptable salts thereof, wherein R1, R2, R3, R4, m, X and Q are as defined below, and novel intermediates used in the synthesis of such compounds. The comp
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