4606-15-9Relevant articles and documents
[Co(MeTAA)] Metalloradical Catalytic Route to Ketenes via Carbonylation of Carbene Radicals
Chirila, Andrei,van Vliet, Kaj M.,Paul, Nanda D.,de Bruin, Bas
, p. 2251 - 2258 (2018/04/09)
An efficient synthetic strategy towards beta-lactams, amides, and esters involving “in situ” generation of ketenes and subsequent trapping with nucleophiles is presented. Carbonylation of carbene radical intermediates using the cheap and highly active cobalt(II) tetramethyltetraaza[14]annulene catalyst [Co(MeTAA)] provides a convenient one-pot synthetic protocol towards substituted ketenes. N-tosylhydrazones are used as carbene precursors, thereby bridging the gap between aldehydes and ketenes. Activation of these carbene precursors by the metalloradical cobalt(II) catalyst affords CoIII-carbene radicals, which subsequently react with carbon monoxide to form ketenes. In the presence of a nucleophile (imine, alcohol, or amine) in the reaction medium the ketene is immediately trapped, resulting in the desired products in a one-pot synthetic protocol. The β-lactams formed upon reaction with imines are produced in a highly trans-selective manner.
Carboxyl activation of 2-mercapto-4,6-dimethylpyrimidine through n-acyl-4,6-dimethylpyrimidine-2-thione: A chemical and spectrophotometric investigation
Rajan
, p. 287 - 291 (2015/01/30)
2-Mercapto-4,6-dimethylpyrimidine, as effective carboxyl activating group, has been successfully proved by converting it into respective acyl derivatives and the subsequent conversion to the amides and esters respectively using amines, amino alcohols and alcohols. The aminolysis and esterification were monitored chemically and spectrophotometrically. This paved way to establish that the above mercaptopyrimidine derivative is an efficient carboxyl activating group applicable in solid phase peptide synthesis.
Efficient microwave-assisted esterification reaction employing methanesulfonic acid supported on alumina as catalyst
Fabian, Lucas,Gomez, Matias,Kuran, Juan A. Caturelli,Moltrasio, Graciela,Moglioni, Albertina
, p. 2386 - 2392 (2014/07/22)
A rapid and efficient protocol assisted by microwave irradiation for the synthesis of esters using methanesulfonic acid (CH3SO3H) supported on Al2O3 (AMA) as catalyst and free of solvent is described. The products were obtained in good yields and purity, with reduced reaction time, and the process is simple and environmentally benign. Copyright
A method for esterification reaction rate prediction of aliphatic monocarboxylic acids with primary alcohols in 1,4-dioxane based on two parametrical taft equation
Vojtko, Jan,Tomcik, Peter
, p. 189 - 196 (2014/02/14)
Esterification reaction rates of aliphatic monocarboxylic acids with primary alcohols in 1,4-dioxane as inert solvent were investigated. Acids were esterified with 1-propanol and alcohols with acetic acid as model reactants at a constant temperature of 60°C, at a fixed ionic strength and pH in a batch reactor with a constant volume. For evaluation of reaction rates, an exact kinetic equation for the equilibrium reaction was applied. Under these conditions and for low reactants, concentrations reaction rate depends only on the structure of reactants and, therefore, can be predicted by a correlation equation with two Taft coefficients (inductive and steric effects). From these equations, it is possible to estimate the esterification reaction rate constant for other acid-alcohol pairs. This methodology may also be suitable for other kinetic systems measured under comparable experimental conditions.
PROCESS FOR SYNTHESIZING PHENYLACETIC ACID BY CARBONYLATION OF TOLUENE
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Paragraph 0032; 0033, (2013/11/19)
A production process for substituted phenylacetic acids or ester analogues thereof is disclosed. In this process toluene or toluene substituted with various substituents, an alcohol, an oxidant and carbon monoxide are used as raw materials to obtain compounds comprising structure of phenylacetic acid ester or analogues thereof by catalysis of the complex catalyst formed from transition metal and ligand, and such compounds are hydrolyzed to obtain various substituted phenylacetic acid based compounds. This type of compounds and their derivatives serve as important fine chemicals used widely in the industries of pharmaceuticals, pesticides, perfume and the like.
Solvent-free esterification of carboxylic acids and alcohols in the presence of silphos [PCl3-n(SiO2)n] as a heterogeneous phosphine reagent
Rao, Ambati Narasimha,Ganesan, Kumaran,Shinde, Chandra Kant
experimental part, p. 2299 - 2308 (2012/06/18)
An efficient solvent-free method for the preparation of esters from various aromatic and aliphatic acids with primary, secondary, and tertiary alcohols using a heterogeneous phosphine reagent, silphos [PCl3-n(SiO 2)n], in good yields is reported.
Palladium-catalyzed oxidative carbonylation of benzylic C-H bonds via nondirected C(sp3)-H activation
Xie, Pan,Xie, Yinjun,Qian, Bo,Zhou, Han,Xia, Chungu,Huang, Hanmin
supporting information; experimental part, p. 9902 - 9905 (2012/08/08)
A new strategy for generating benzylpalladium reactive species from toluenes via nondirected C(sp3)-H activation has been developed. This led to construction of an efficient Pd-catalyzed reaction protocol for the oxidative carboxylation of benzylic C-H bonds to form substituted 2-phenylacetic acid esters and derivatives from inexpensive, commercially available starting materials.
Pd-catalyzed decarboxylative cross-couplings of potassium malonate monoesters with aryl halides
Feng, Yi-Si,Wu, Wei,Xu, Zhong-Qiu,Li, Yan,Li, Ming,Xu, Hua-Jian
, p. 2113 - 2120 (2012/03/26)
An efficient catalytic protocol for Pd-catalyzed decarboxylative cross-coupling of potassium malonate monoesters and derivatives with aryl bromides and chlorides are described. Because of its broad applicability, this new catalytic system provides an alternative method for the preparation of diverse aryl acetic acids and derivatives.
Alcoholysis of naturally occurring imides: Misleading interpretation of antifungal activities
Pacher, Thomas,Raninger, Adriane,Lorbeer, Eberhard,Brecker, Lothar,But, Paul Pui-Hay,Greger, Harald
body text, p. 1389 - 1393 (2010/11/04)
The frequent presence of the sulfur-containing amide penangin (10) in leaf extracts of Glycosmis species turned out to be the result of decomposition of imides generated by extraction and storage in MeOH. Reinvestigation of Glycosmis mauritiana and G. cf. puberula with acetone revealed the presence of six imides. In addition to penimides A (1) and B (2) and ritigalin (6), three new derivatives, krabin (4), isokrabin (5), and methoxypenimide B (3), were isolated and identified by spectroscopic methods. All six imides were shown to be susceptible to different rates of methanolic cleavage, leading to their corresponding methyl esters and sulfur-containing amides. Whereas the decomposition products penangin (10), isopenangin (11), and sinharin (14) are known, the corresponding cleavage of methyl N-methylthiocarbamate (7) from ritigalin (6), monitored in situ by 1H NMR spectroscopy, is described here for the first time. Its structure was further confirmed by GC-MS coupling. HPLC-UV comparison of many different samples of G. mauritiana, extracted with MeOH, revealed considerable chemical variations in sulfur-containing amides, strongly correlated with different antifungal potency. The lack of activity of many methanolic crude extracts can be explained by a preponderance of the inactive decomposition product penangin (10), whereas the corresponding naturally occurring imides penimides A (1) and B (2) and methoxypenimide B (3), extracted with acetone, showed high fungitoxic properties.
Oxidation of substituted β-diketones with hydrogen peroxide: Synthesis of esters through the formation of bridged 1,2,4,5-tetraoxanes
Terentev, Alexander O.,Borisov, Dmitry A.,Yaremenko, Ivan A.,Ogibin, Yuri N.,Nikishin, Gennady I.
experimental part, p. 1145 - 1149 (2010/06/14)
Acid-catalyzed oxidation of alkyl- and benzyl-substituted -diketones by hydrogen peroxide at 79-120C in a mixture of an alcohol and a strong acid (sulfuric acid, tetrafluoroboric acid, or perchloric acid) gave the corresponding esters through the formation of bridged 1,2,4,5-tetraoxanes. Georg Thieme Verlag Stuttgart · New York.
