- Phenol Derivatives in Ruthenium-Catalyzed C–H Arylation: A General Synthetic Access to Azole-Based Congested Polyaromatics
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Aryl triflates and related phenolates are suitable electrophile coupling partners for the ruthenium-catalyzed direct arylation of heteroaromatic substrates using azole N-directed Csp2–H activation. We report herein convenient conditions for the efficient ortho-C–H functionalization of aryl-pyrazoles, thiazoles and pyridines in which [RuCl2(p-Cym)]2 precatalyst is employed with pivalic acid (PivOH) as co-catalyst. Different phenolate derivatives were successfully coupled, which tolerate a large scope of electron-rich substituents in para-, meta- and highly hindered ortho-position. Electron-withdrawing aryl triflates were found to be less reactive, making the general reactivity of these electrophiles complementary to those of aryl chlorides and deactivated bromides. This cost-effective ruthenium C–H activation/arylation synthesis of poly(hetero)aromatics was concurrently examined using triflates, mesylates, sulfonates, and carbonates, and was also successfully extended to the use of diethyl carbonate as an eco-friendly solvent.
- Roger, Julien,Hierso, Jean-Cyrille
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supporting information
p. 4953 - 4958
(2018/09/25)
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- Oxidative Addition of Aryl Electrophiles to a Prototypical Nickel(0) Complex: Mechanism and Structure/Reactivity Relationships
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Detailed kinetic studies of the reaction of a model Ni0 complex with a range of aryl electrophiles have been conducted. The reactions proceed via a fast ligand exchange pre-equilibrium, followed by oxidative addition to produce either [NiIX(dppf)] (and biaryl) or [NiII(Ar)X(dppf)]; the ortho substituent of the aryl halide determines selectivity between these possibilities. A reactivity scale is presented in which a range of substrates is quantitatively ranked in order of the rate at which they undergo oxidative addition. The rate of oxidative addition is loosely correlated to conversion in prototypical cross-coupling reactions. Substrates that lead to NiI products in kinetic experiments produce more homocoupling products under catalytic conditions.
- Bajo, Sonia,Laidlaw, Gillian,Kennedy, Alan R.,Sproules, Stephen,Nelson, David J.
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supporting information
p. 1662 - 1672
(2017/04/28)
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- A new, mild, general and efficient route to aryl ethyl carbonates in solvent-free conditions promoted by magnesium perchlorate
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A new, general and mild method for the direct synthesis of aryl and alkyl ethyl carbonates promoted by a Lewis acid is reported. The reaction proceeds smoothly with diethyl dicarbonate in the presence of Mg(ClO4) 2, a specific activator of 1,3-dicarbonyl compounds, and shows general applicability. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Bartoli, Giuseppe,Bosco, Marcella,Carlone, Armando,Locatelli, Manuela,Marcantoni, Enrico,Melchiorre, Paolo,Palazzi, Paolo,Sambri, Letizia
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p. 4429 - 4434
(2007/10/03)
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- Sodium Hydrogen Telluride- An Efficient Reagent for Deblocking of Aryl Ethyl Carbonates
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Sodium hydrogen telluride is found to be a mild and efficient reagent for deblocking of aryl ethyl carbonates.
- Shobana, N.,Amirthavalli, M.,Deepa, V.,Shanmugam, P.
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p. 965 - 966
(2007/10/02)
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