- Palladium-catalyzed ortho-C-H hydroxylation of benzoic acids
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A simple Pd(OAc)2 catalyzed ortho-hydroxylation of benzoic acids using TBHP as the sole oxidant has been explored. This protocol features relatively broad substrate scope and operational simplicity. The compatibility of ortho-substituted substrates is an effective complement to the previous ortho-hydroxylation reaction.
- Luo, Feihua,He, Shuhua,Gou, Quan,Chen, Jinyang,Zhang, mingzhong
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- Carboxylation of o-, m-, and p-chlorophenols with sodium ethyl carbonate
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The possibility for the synthesis of 5-chloro-2-hydroxybenzoic, 4-chloro-2-hydroxybenzoic, and 3-chloro-2-hydroxybenzoic acids via regioselective carboxylation of p-, m-, and o-chlorophenols, respectively, with sodium ethyl carbonate has been demonstrated
- Suerbaev, Kh. A.,Chepaikin,Kudaibergenov, N. Zh.
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p. 436 - 440
(2017/07/05)
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- Carboxylation of Phenols with CO2 at Atmospheric Pressure
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A convenient and efficient method for the ortho-carboxylation of phenols under atmospheric CO2 pressure has been developed. This method provides an alternative to the previously reported Kolbe-Schmitt method, which requires very high pressures of CO2. The addition of a trisubstituted phenol has proved essential for the successful carboxylation of phenols with CO2 at standard atmospheric pressure, allowing the efficient preparation of a broad variety of salicylic acids.
- Luo, Junfei,Preciado, Sara,Xie, Pan,Larrosa, Igor
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supporting information
p. 6798 - 6802
(2016/05/11)
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- Regioselective ortho-carboxylation of phenols catalyzed by benzoic acid decarboxylases: A biocatalytic equivalent to the Kolbe-Schmitt reaction
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The enzyme catalyzed carboxylation of electron-rich phenol derivatives employing recombinant benzoic acid decarboxylases at the expense of bicarbonate as CO2 source is reported. In contrast to the classic Kolbe-Schmitt reaction, the biocatalytic equivalent proceeded in a highly regioselective fashion exclusively at the ortho-position of the phenolic directing group in up to 80% conversion. Several enzymes were identified, which displayed a remarkably broad substrate scope encompassing alkyl, alkoxy, halo and amino- functionalities. Based on the crystal structure and molecular docking simulations, a mechanistic proposal for 2,6-dihydroxybenzoic acid decarboxylase is presented.
- Wuensch, Christiane,Gross, Johannes,Steinkellner, Georg,Lyskowski, Andrzej,Gruber, Karl,Glueck, Silvia M.,Faber, Kurt
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p. 9673 - 9679
(2014/03/21)
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- PD(II)-CATALYZED HYDROXYLATION OF ARENES WITH O2 OR AIR
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Pd (II) -catalyzed ortho-hydroxylat ion of variously substituted aromatic carboxylic acids under O2 or air is achieved under non-acidic conditions. Extensive labeling studies support a direct oxygenation of aryl C-H bonds with molecular oxygen.
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Page/Page column 14
(2011/04/24)
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- Pd(II)-catalyzed hydroxylation of arenes with 1 atm of O2 or air
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(Chemical Equation Presented) Pd(II)-catalyzed ortho-hydroxylation of variously substituted benzoic acids under 1 atm of O2 or air is achieved under nonacidic conditions. Extensive labeling studies support a direct oxygenation of aryl C-H bonds with molecular oxygen.
- Zhang, Yang-Hui,Yu, Jin-Quan
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supporting information; experimental part
p. 14654 - 14655
(2010/01/06)
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- Process for the synthesis of hydroxy aromatic acids
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Hydroxy aromatic acids are produced in high yields and high purity (>95%) from halogenated aromatic acids in a reaction mixture containing a copper source and a ligand that coordinates to copper.
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Page/Page column 20-21
(2008/06/13)
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- The site-selective functionalization of halogen-bearing phenols: An exercise in diversity-oriented organometallic synthesis
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The organometallic approach to diversity-oriented organic synthesis was subjected to a further test, this time in the phenol series. The model compounds selected were 2,3,6-trifluorophenol, the three isomers of (trifluoromethoxy) phenol and the three isomers of chlorophenol. A combination of optionally site selective metalations and protective group-controlled metalations enabled the selective generation of several isomeric intermediates in each case and their subsequent conversion into functionalized derivatives, in particular hydroxybenzoic acids.
- Marzi, Elena,Schlosser, Manfred
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p. 3393 - 3401
(2007/10/03)
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- Synthesis of salicylic acid derivatives in presence of ultrasonic irradiation using water as solvent
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An improved synthesis of salicylic acid using ultrasonic irradiation and water as solvent can be achieved with copper and pyridine as catalysts. A number of salicylic acids were prepared in good yield and in a short reaction time.
- Docampo Palacios, Maite L.,Pellon Comdom, Rolando F.
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p. 1783 - 1787
(2007/10/03)
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- Synthesis of salicylic acid derivatives from the corresponding 2-chlorobenzoic acid using water as solvent
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An improved synthesis of salicylic acid using water as solvent can be achieved using the Ullmann-Goldberg reaction conditions in presence of pyridine as cocatalyst. A number of salicylic acids were prepared in good yield.
- Pellon Comdom, Rolando F.,Docampo Palacios, Maite L.
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p. 2055 - 2059
(2007/10/03)
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- Metal Template ortho-Acylation of Phenols. Direct Synthesis of Salicylic Acid Chlorides and Derivatives
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A direct synthesis of salicylic acid chlorides is achieved via "metal-driven" intracomplex acylation of bromomagnesium and aluminum phenoxides with phosgene.Salicylic acids 5 and some derivatives 6, 7 can be obtained by quenching the reaction mixture with convenient reagents.Moreover the reaction of lithium phenylacetylide with 3 provides a new convenient approach to ortho-hydroxyaryl alkynyl ketones like 8.The oriented complex 2, involving the metal phenoxide and phosgene is proposed to account for the ortho-regioselective control of the reaction.
- Sartori, Giovanni,Casnati, Giuseppe,Bigi, Franca,Bonini, Giovanni
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p. 763 - 766
(2007/10/02)
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- Electrophilic Catalysis of Sulphate (-SO3-) Group Transfer: Hydrolysis of Salicyl Sulphates assisted by Intramolecular Hydrogen Bonding
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The hydrolysis of substituted salicyl sulphates has been measured over a range of pH values at 70 deg C to obtain kinetic parameters for hydronium ion (kH) and carboxylic acid (kp) calalysis.A Jaffe treatment of the carboxy-catalysis parameter for a range of nuclear substituents yields ρphenol 1.51; ρcarboxy 0 indicates that the carboxy-function does not ionise on going from the ground- to the transition-state, consistent with hydrogen bonding rather than catalysis through proton transfer.The change in 'effective' charge on the phenol oxygen on going from the ground- to the transition-state confirms less build up of negative charge than in the uncatalysed hydrolysis of aryl sulphates.
- Hopkins, Andrew Ramsay,Green, Adam Llywellyn,Williams, Andrew
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p. 1279 - 1284
(2007/10/02)
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