- 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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- Synthesis of cresotic acids by carboxylation of cresols with sodium ethyl carbonate
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Carboxylation of o-cresol, m-cresol, and p-cresol with sodium ethyl carbonate (SEC) proceeds regioselectively with the formation of cresotic acids: 2-hydroxy-3-methylbenzoic acid, 2-hydroxy-4-methylbenzoic acid, and 2-hydroxy-5-methylbenzoic acid, respectively. Optimal conditions for conducting the process have been found to be as follows: the reactants ratio of [cresol]: [sodium ethyl carbonate] = (1.5–2): 1, T = 180–185°C, PCO2 = 10 atm, and t = 6–7 h. Simple and convenient methods for the synthesis of cresotic acids, which can be used for their industrial manufacturing, have been developed.
- Suerbaev, Kh. A.,Chepaikin,Kudaibergenov, N. Zh.,Zhaksylykova, G. Zh.
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p. 646 - 650
(2016/08/16)
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- A versatile approach for the synthesis of para -substituted arenes via palladium-catalyzed C-H functionalization and protodecarboxylation of benzoic acids
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While a great number of ortho C-H functionalization reactions have been developed and several breakthroughs have been achieved in meta C-H activation, para C-H functionalization is still in its infancy stage. In this article, a versatile strategy for the synthesis of para-substituted arenes has been developed via a tandem process consisting of palladium-catalyzed C-H functionalization and subsequent copper-catalyzed protodecarboxylation of benzoic acids. Both electron-withdrawing and electron-donating functionalities can be introduced into the para positions of arenes bearing a variety of substituents.
- Pan, Shulei,Zhou, Bo,Zhang, Yanghui,Shao, Changdong,Shi, Guangfa
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supporting information
p. 277 - 281
(2016/01/20)
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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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- A concise synthetic route to the stereotetrad core of the briarane diterpenoids
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A concise synthesis (under 10 steps) of the stereotetrad core of the briarane diterpenoids is reported. This approach harnesses the unique reactivity of salicylate ester derived 2,5-cyclohexadienones to quickly build complexity. In particular, a highly diastereoselective acetylide conjugate addition/β-ketoester alkylation sequence was used to set the relative configuration of the C1 (quaternary) and C10 (tertiary) vicinal stereocenters. The sterochemical outcome of the β-ketoester alkylation appears to be governed by torsional steering in the transition state.
- Moon, Nicholas G.,Harned, Andrew M.
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supporting information
p. 2218 - 2221
(2015/05/13)
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- A Baker-Venkataraman retro-Claisen cascade delivers a novel alkyl migration process for the synthesis of amides
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A simple extension of the carbamoyl Baker-Venkataraman rearrangement has been developed. If residual water in the reaction is not strictly excluded a Baker-Venkataraman retro-Claisen cascade takes place, giving amide products, in which an alkyl group apparently migrates between two functionalities of the substrate.
- Ameen, Dana,Snape, Timothy J.
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supporting information
p. 1816 - 1819
(2015/03/30)
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- General method for the synthesis of salicylic acids from phenols through palladium-catalyzed silanol-directed C-H carboxylation
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A silanol-directed, palladium-catalyzed C-H carboxylation reaction of phenols to give salicylic acids has been developed. This method features high efficiency and selectivity, and excellent functional-group tolerance. The generality of this method was demonstrated by the carboxylation of estrone and by the synthesis of an unsymmetrically o,o′-disubstituted phenolic compound through two sequential C-H functionalization processes.
- Wang, Yang,Gevorgyan, Vladimir
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p. 2255 - 2259
(2015/02/19)
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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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- Sulfoximines: A reusable directing group for chemo-and regioselective ortho C-H oxidation of arenes
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Sulfoximines direct: A new protocol for the chemo-and regioselective ortho C-H acetoxylation of arenes in N-benzoylated sulfoximines is reported. The sulfoximine directing group is easily detached from the C-H oxidation product through acid-promoted hydrolysis, isolated, and reused (see scheme). The meta-substituted phenols are synthesized following this strategy and the stereointegrity of the sulfoximine is preserved in this transformation. C(sp3)-H acetoxylation of the methyl group is also demonstrated.
- Yadav, M. Ramu,Rit, Raja K.,Sahoo, Akhila K.
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supporting information; experimental part
p. 5541 - 5545
(2012/06/01)
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- Phenolic acid glucosides from the seeds of Entada phaseoloides Merill
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Phytochemical investigation of the defatted seeds of Entada phaseoloides Merill. (Mimosaceae) led to the isolation of three new phenolic acid glucosides, which were characterized as 2-hydroxy-5-methylbenzoyl-β-L-glucopyranoside (p-cresotyl glucoside, 1), 2-hydroxy-5-methylbenzoyl-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranoside (p-cresotyl triglucoside, 2), and 2-hydroxybenzoyl-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranoside (salicylic acid tetraglucoside, 5), along with sucrose and triglucoside. The structures of these phytoconstituents have been established on the basis of spectral data analysis and chemical reactions.
- Singh, Onkar,Ali, Mohd,Akhtar, Nida
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body text
p. 682 - 687
(2011/09/21)
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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 12; 18
(2011/04/24)
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- INHIBITORS OF STEAROYL-COA DESATURASE
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Provided herein are compounds of the formula (I): as well as pharmaceutically acceptable salts thereof, wherein the substituents are as those disclosed in the specification. These compounds, and the pharmaceutical compositions containing them, are useful for the treatment of diseases such as, for example, obesity.
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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 discovery of fluoropyridine-based inhibitors of the Factor VIIa/TF complex
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The activated Factor VII/tissue factor complex (FVIIa/TF) plays a key role in the formation of blood clots. Inhibition of this complex may lead to new antithrombotic drugs. An X-ray crystal structure of a fluoropyridine-based FVIIa/TF inhibitor bound in the active site of the enzyme complex suggested that incorporation of substitution at the 5-position of the hydroxybenzoic acid side chain could lead to the formation of more potent inhibitors through interactions with the S1′/S2′ pocket.
- Kohrt, Jeffrey T.,Filipski, Kevin J.,Cody, Wayne L.,Cai, Cuiman,Dudley, Danette A.,Van Huis, Chad A.,Willardsen, J. Adam,Rapundalo, Stephen T.,Saiya-Cork, Kamlai,Leadley, Robert J.,Narasimhan, Lakshmi,Zhang, Erli,Whitlow, Marc,Adler, Marc,McLean, Kirk,Chou, Yuo-Ling,McKnight, Cecile,Arnaiz, Damian O.,Shaw, Kenneth J.,Light, David R.,Edmunds, Jeremy J.
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p. 4752 - 4756
(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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- External preparation for skin
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An external preparing for skin comprising one or more than two types of 2-hydroxy benzoic acid derivative and/or salt thereof represented by the following formula: STR1 wherein R is an alkoxy group or alkyl group in the formula. The external preparation for the skin according to the present invention has a suppression effect on melanine generation by inhibition of tyrosinase activity. Accordingly, an excellent bleaching effect based upon the suppression of chromatosis and a high degree of safety can be obtained.
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- REACTIONS WITH 2-METHYLCHROMONES
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The reactivity of 2-methylchromones and their derivatives towards nucleophilic and electrophilic reagents, cycloaddition reactions, thiation, reactions with compounds containing active methylene group has been investigated.The IR, 1H-NMR and mass spectra of new chromone derivatives were discussed.Key words: 2-Methylchromones, cycloaddition reactions with compounds containing active methylene
- Hamed, Ashraf A.,Madkour, Hassan M. F.,Nuaimi, Ibrahim S. Al.,Hussain, Badria A.
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p. 359 - 364
(2007/10/02)
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- Reimer-Thiemann reaction using carbon tetrachloride
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The title reaction has been carried out on the three isomeric cresols, thymol and 3,4-dimethylphenol, and the phenolic carboxylic acids so obtained have been characterised.
- Gaonkar, A. V.,Kirtany, J. K.
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p. 800 - 801
(2007/10/02)
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- Metal ion catalysis of the decomposition of transient 2-carboxy-2,5-cyclohexadienones in aqueous solution
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Bromide ion induced debromination of the anion of 4-bromo-4-methyl-2,5-cyclohexadienone-2-carboxylic acid (1) is catalyzed by cupric ions and ferric ions.Similarly, the enolization of the anion of the benzocyclohexadienone 3, which is formed during the bromination of 1-naphthol-2-carboxylic acid, is catalyzed by some metal ions.The origin of the catalysis in these reactions is strong metal ion binding to the incipient dianion products that are of the salicylate type.Evidence for this is that the efficiency of the metal (and hydrogen) ion catalysis parallels the stability of the analogous complexes with the salicylate dianion.
- Tee, Oswald S.,Iyengar, N. Rani
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p. 1194 - 1198
(2007/10/02)
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- Synthesis and Reactions of 4,5-Dichloro-1,2,3-dithiazolium Chloride
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Disulfur dichloride reacts with acetonitrile via chloro- and dichloroacetonitrile to give finally 4,5-dichloro-1,2,3-dithiazolium chloride (1).The reactivity of 1 with proton-active compounds is determined by the nucleophilic substitution of the chlorine at carbon atom C-5.Substrates like H2O, H2S, primary amines, and sulfonamides, having two active hydrogen atoms, form the covalent 4-chloro-5H-1,2,3-dithiazole derivatives 2, 3, 5. 1 reacts with phenols in o- or p-position by an electrophilic attack to form 4-chloro-5-(hydroxyphenyl)-1,2,3-dithiazolium chlorides 9a - d.HCl elimination from these leads to deep violet, metallic-reflecting crystals of the betaine-like neutral molecules 10a, b.X-ray analysis shows a planar structure of 10a and a molecular arrangement of a right and a left helix.Ring cleavage of 1 with chlorine gives compounds 14, 15; correspondingly, 2 reacts with chlorine to yield 2-chloro-2-(chlorothioimino)acetyl chloride (18).
- Appel, Rolf,Janssen, Heinrich,Siray, Mustafa,Knoch, Falk
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p. 1632 - 1643
(2007/10/02)
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- SELECTIVE SYNTHESES USING CYCLODEXTRINS AS CATALYSTS. 2. PARA-ORIENTED CARBOXYLATION OF PHENOLS.
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4-Hydroxybenzoic acid and 4-hydroxy-3-methylbenzoic acid are synthesized in virtually 100% selectivities and high yields from the corresponding phenols and carbon tetrachloride by using beta -cyclodextrin ( beta -CD) as catalyst. The selective syntheses are successfully achieved by a small molar ratio, even 0. 03, of beta -CD to phenols and are hardly suppressed by oxygen. Kinetic study shows that the selective catalyses by beta -CO originate from both promotion of the para carboxylation and almost complete inhibition of the ortho carboxylation. Heptakis(2,6-di-0-methyl) beta -cyclodextrin in contrast decreases the para selectivity, showing the importance of the hydroxyl groups of beta -CD in its selective catalysis. The selective catalysis by beta -CD proceeds via formation of a molecular complex with the active species, probably the trichloromethyl cation.
- Komiyama,Hirai
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p. 174 - 178
(2007/10/02)
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- Benzamide derivatives
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Benzamide derivatives of the formula:- STR1 wherein R1 represents a fluorine, chlorine or bromine atom, or an alkyl, alkoxy, alkylthio, alkylsulphonyl, alkanoylamino, alkylamino or alkylsulphamoyl group, each such group containing from 1 to 6 carbon atoms, a dialkylsulphamoyl, dialkylamino or dialkylcarbamoyl group (wherein the two alkyl groups may be the same or different and each contains from 1 to 4 carbon atoms), an alkanoyl, alkoxycarbonyl, alkoxycarbonylamino or alkylcarbamoyl group containing from 2 to 6 carbon atoms, or a hydroxy, formyl, nitro, trifluoromethyl, aryl, benzyloxycarbonylamino, amino, sulphamoyl, cyano, tetrazol-5-yl, carboxy, carbamoyl or aroyl group, and n represents an integer 1, 2 or 3, are new compounds possessing pharmacological properties, in particular properties of value in the treatment of respiratory disorders manifested by the interaction of tissue-fixed antibodies with specific antigens.
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