- Identification of an Oxalamide Ligand for Copper-Catalyzed C?O Couplings from a Pharmaceutical Compound Library
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A typical pharmaceutical compound library is stocked with molecular diversity and could provide a platform for the discovery of new ligand structures. Herein, we describe the use of this approach in combination with high throughput screening to identify N,N’-bis(thiophene-2-ylmethyl)oxalamide as a ligand that is generally effective for copper-catalyzed C?O cross-couplings to prepare both biarylethers as well as phenols under mild conditions.
- Chan, Vincent S.,Krabbe, Scott W.,Li, Changfeng,Sun, Lijie,Liu, Yue,Nett, Alex J.
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- Open-Resonance-Assisted Hydrogen Bonds and Competing Quasiaromaticity
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The delocalization of electron density upon tautomerization of a proton across a conjugated bridge can alter the strength of hydrogen bonds. This effect has been dubbed resonance-assisted hydrogen bonding (RAHB) and plays a major role in the energetics of the tautomeric equilibrium. The goal of this work was to investigate the role that π-delocalization plays in the stability of RAHBs by engaging other isomerization processes. Similarly, acid-base chemistry has received little experimental attention in studies of RAHB, and we address the role that acid-base effects play in the tautomeric equilibrium. We find that π-delocalization and the disruption of adjacent aromatic rings is the dominant effect in determining the stability of a RAHB.
- Nguyen, Yen H.,Lampkin, Bryan J.,Venkatesh, Amrit,Ellern, Arkady,Rossini, Aaron J.,Vanveller, Brett
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p. 9850 - 9857
(2018/08/01)
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- A catalytic oxidation fragrant boron class compound preparing phenol method (by machine translation)
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The invention discloses a method for catalytic oxidation of phenolic compounds fragrant boron class compound synthesis method, the flux in the solvent in the aqueous solution, under the action of alkali, adding hydrazine hydrate or acid hydrazides catalyst, catalytic oxidation fragrant boron class compound directly for the preparation of phenolic compound. The invention of the method of preparation of the phenol compound, the catalyst is a cheap hydrazine hydrate or hydrazine compound, the oxidizing agent is atmospheric pressure of air or oxygen, the reaction does not need good and activeness metal catalyst, is extensive and stable substrate, substrate-sensitive functional group compatibility good and wide range of application. In the optimized under the reaction conditions, the yield of the target product separation up to 99%. (by machine translation)
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Paragraph 0073; 0121; 0122
(2017/08/08)
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- Oxidative Addition Complexes as Precatalysts for Cross-Coupling Reactions Requiring Extremely Bulky Biarylphosphine Ligands
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In this report, we describe the application of palladium-based oxidative addition complexes (OACs) as effective precatalysts for C-N, C-O, and C-F cross-coupling reactions with a variety of (hetero)arenes. These complexes offer a convenient alternative to previously developed classes of precatalysts, particularly in the case of the bulkiest biarylphosphine ligands, for which palladacycle-based precatalysts do not readily form. The precatalysts described herein are easily prepared and stable to long-term storage under air.
- Ingoglia, Bryan T.,Buchwald, Stephen L.
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supporting information
p. 2853 - 2856
(2017/06/07)
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- Reagent Design and Ligand Evolution for the Development of a Mild Copper-Catalyzed Hydroxylation Reaction
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Parallel synthesis and mass-directed purification of a modular ligand library, high-throughput experimentation, and rational ligand evolution have led to a novel copper catalyst for the synthesis of phenols with a traceless hydroxide surrogate. The mild reaction conditions reported here enable the late-stage synthesis of numerous complex, druglike phenols.
- Fier, Patrick S.,Maloney, Kevin M.
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supporting information
p. 3033 - 3036
(2017/06/07)
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- Copper-Catalyzed Hydroxylation of (Hetero)aryl Halides under Mild Conditions
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The combination of Cu(acac)2 and N,N′-bis(4-hydroxyl-2,6-dimethylphenyl)oxalamide (BHMPO) provides a powerful catalytic system for hydroxylation of (hetero)aryl halides. A wide range of (hetero)aryl chlorides bearing either electron-donating or -withdrawing groups proceeded well at 130 °C, delivering the corresponding phenols and hydroxylated heteroarenes in good to excellent yields. When more reactive (hetero)aryl bromides and iodides were employed, the hydroxylation reactions completed at relatively low temperatures (80 and 60 °C, respectively) at low catalytic loadings (0.5 mol % Cu).
- Xia, Shanghua,Gan, Lu,Wang, Kailiang,Li, Zheng,Ma, Dawei
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supporting information
p. 13493 - 13496
(2016/10/31)
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- Strong positive cooperativity in binding to the A3T3 repeat by Hoechst 33258 derivatives attaching the quinoline units at the end of a branched linker
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Hoechst 33258 derivatives with additional interacting moieties attached at the ends of branched linkers were synthesized, and their DNA binding properties were investigated with regard to the A3T3 repeat by measuring fluorescence spectra. The binding prop
- Koda, Hironori,Brazier, John Alan,Onishi, Ippei,Sasaki, Shigeki
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supporting information
p. 4583 - 4590
(2015/08/03)
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- Palladium-catalyzed hydroxylation of aryl and heteroaryl halides enabled by the use of a palladacycle precatalyst
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A method for the hydroxylation of aryl and heteroaryl halides, promoted by a catalyst based on a biarylphosphine ligand tBuBrettPhos (L5) and its corresponding palladium precatalyst (1), is described. The reactions allow the cross-coupling of both potassium and cesium hydroxides with (hetero)aryl halides to afford a variety of phenols and hydroxylated heteroarenes in high to excellent yield.
- Cheung, Chi Wai,Buchwald, Stephen L.
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p. 5351 - 5358
(2014/06/23)
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- Efficient microwave-assisted Pd-catalyzed hydroxylation of aryl chlorides in the presence of carbonate
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An efficient microwave-assisted, palladium-catalyzed hydroxylation of aryl chlorides in the presence of a weak base carbonate was developed, which rapidly converts aryl and heteroaryl chlorides to phenols, and can be used when the aryl chloride is functionalized with a ketone, aldehyde, ester, nitrile, or amide.
- Yu, Chao-Wu,Chen, Grace S.,Huang, Chen-Wei,Chern, Ji-Wang
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supporting information; experimental part
p. 3688 - 3691
(2012/08/28)
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