72092-48-9Relevant academic research and scientific papers
ZWITTERIONIC CATALYSTS FOR (TRANS)ESTERIFICATION: APPLICATION IN FLUOROINDOLE-DERIVATIVES AND BIODIESEL SYNTHESIS
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Paragraph 0013; 0028, (2021/01/29)
An amide/iminium zwitterion catalyst has a catalyst pocket size that promotes transesterification and dehydrative esterification. The amide/iminium zwitterions are easily prepared by reacting aziridines with aminopyridines. The reaction can be applied a wide variety of esterification processes including the large-scale synthesis of biodiesel. The amide/iminium zwitterions allow the avoidance of strongly basic or acidic condition and avoidance of metal contamination in the products. Reactions are carried out at ambient or only modestly elevated temperatures. The amide/iminium zwitterion catalyst is easily recycled and reactions proceed in high to quantitative yields.
Amide/Iminium Zwitterionic Catalysts for (Trans)esterification: Application in Biodiesel Synthesis
Lam, Ying-Pong,Ng, Wing-Hin,Tan, Fei,Tse, Ying-Lung Steve,Wang, Xinyan,Yeung, Ying-Yeung
, p. 8083 - 8092 (2019/08/26)
A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic moiety interacting with the carbonyl substrates through nonclassical hydrogen bonding. The reaction can be applied to large-scale synthesis of biodiesel under mild conditions.
Selective acetylation of primary alcohols by ethyl acetate
Singha, Raju,Ray, Jayanta K.
, p. 5395 - 5398 (2016/11/11)
A KOtBu and ethyl acetate mediated efficient methodology has been developed for the acetylation of primary and secondary alcohols where ethyl acetate is the source of acetyl group. The reaction is fast, mild, efficient, and highly selective towards the primary alcohols.
Trialkylsilyl triflimides as easily tunable organocatalysts for allylation and benzylation of silyl carbon nucleophiles with non-genotoxic reagents
Mendoza, Oscar,Rossey, Guy,Ghosez, Léon
supporting information; experimental part, p. 2571 - 2575 (2010/06/21)
Trialkylsilyl triflimides generated in situ are unique catalysts for the electrophilic benzylation or allylation of trialkylsilylenol ethers or allyl trialkylsilanes with non-genotoxic alkylating reagents such as benzyl and allyl acetates. In most cases the reactions are fast at room temperature and yields are high. The reaction works particularly well with electron-rich benzyl donors including derivatives of pyrrole, indole and furane.
A switchable oxidation process leading to two various versatile pharmaceutical intermediates
Occhipinti, Giovanni,Liguori, Lucia,Tsoukala, Anna,Bjorsvik, Hans-Rene
supporting information; experimental part, p. 1379 - 1384 (2011/09/20)
An efficient high-yielding and environmentally benign switchable oxidation process that can selectively produce two different versatile synthetic intermediates is disclosed. One of the two intermediates, 2,3-dimethoxy-5- methylcyclohexa-2,5-diene-1,4-dione (coenzyme Q0), is obtained by means of a telescoped two-step synthetic protocol that in the first step involves treatment of the substrate (1,2,3-trimethoxy-5-methylbenzene) with hydrogen peroxide in acetic acid with p-toluene sulphonic acid present as a Bronsted acid catalyst, succeeded by a telescoped second step that entails treatment with fuming nitric acid to achieve the target molecule in an excellent isolated yield (88%). If the substrate is treated directly with nitric acid (65%) in glacial acetic acid two different products can be obtained, namely acetic acid 3,4,5-trimethoxybenzyl ester in a superb isolated yield (93%) or, under slightly altered reaction conditions, 1,2,3-trimethoxy-5- (nitromethyl)benzene in a moderate to low yield (35%) and low selectivity. The two pathways leading to the two different products in the nitric acid oxidation protocol were investigated by means of DFT calculations as an aid to elaborate a proposal for the reaction mechanism.
Novel intermediates, process for their preparation and synthesis of 1, 4-benzoquiones
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Page/Page column 4, (2008/12/09)
The present invention discloses a new process for the preparation of 1,4-benzoquiones of formula (II) wherein R1, R2, R3 and R4 are independently selected from the group consisting of branched or unbranched C1-C6 alkyl, phenyl and benzyl, wherein phenyl and benzyl is optionally substituted by one or more substituent independently selected from the group consisting of C1-C6 alkyl and halogen, and wherein C1-C6 alkyl is optionally substituted with one or more halogen susbstituents, and wherein R2 and R3 together can form a C1-C6-alkylene radical, optionally substituted by one or more susbstituents independently selected from the group comprising C1-C6, benzyl, phenyl and halogen. One preferred compound is 2,3-dimethoxy-5-methyl-[1,4]benzoquinone, also known as coenzyme Q0 (CoQ0). Also disclosed are novel compounds and intermediates, and a method for the preparation of coenzyme Qn, preferable the coenzyme Q10. Also disclosed is a method for continuous synthesis of 1,4-benzoquiones in a continuous flow reactor.
Photoacylation of alcohols in neutral medium
Debieux, Jean-Luc,Cosandey, Anne,Helgen, Celine,Bochet, Christian G.
, p. 2073 - 2077 (2008/02/04)
We report here conditions which allow the photoacylation of primary, secondary and tertiary alcohols with N-acetyl-5,7-dinitroindoline under exceptionally mild conditions, at wavelengths harmless to most functional groups, including otherwise photosensitive ones. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
A facile one-step conversion of aromatic aldehydes to acetates
Baruah
, p. 60 - 61 (2007/10/03)
Aromatic aldehydes are efficiently converted to the corresponding benzyl acetates with acetic anhydride and zinc in the presence of acidic aluminium oxide in dichloromethane at room temperature.
Oxidations of benzyl and phenethyl phenyl sulfides. Implications for the mechanism of the microsomal and biomimetic oxidation of sulfides
Baciocchi, Enrico,Lanzalunga, Osvaldo,Pirozzi, Bruno
, p. 12287 - 12298 (2007/10/03)
The study of the oxidation of 4-methoxyphenethyl phenyl sulfide and 3,4-dimethoxyphenethyl phenyl sulfide with potassium 12-tungstocobalt(III)ate [Co(III)W] suggests that in the radical cations of 3,4,5-(MeO)3PhCH2SPh (4) and 2,4,6(MeO)3PhCH2SPh (5) the positive charge is not localized on the sulfur atom, but in the benzylic aromatic ring. Nevertheless, in the biomimetic and microsomal oxidation of 4 and 5 the products observed are exclusively sulfoxides and sulfones, which appears in contrast with a mechanism involving the formation of an intermediate sulfide radical cation followed by a fast oxygen rebound. A direct oxygen transfer mechanism seems most likely.
The Photochemistry of Methoxy-Substituted Benzyl Acetates and Benzyl Pivalates: Homolytic vs Heterolytic Cleavage
Pincock, J. A.,Wedge, P. J.
, p. 5587 - 5595 (2007/10/02)
The multiple methoxy-substituted benzyl acetates (3g-i) and benzyl pivalates (4g-i) have been photolyzed in methanol solution.The products of these reactions are derived from two critical intermediates; the benzyl radical/acyloxy radical pair and the benzyl cation/carboxylate anion pair.As predicted by the meta effect, the yield of ion-derived product, the methyl ether in this case, was enhanced by the presence of the m-methoxy groups.The yield of ether, for the acetate esters, varied from 2percent for the 4-methoxy-substituted ester to 66percent for the 3,4,5-trimethoxy-substituted ester.In contrast, the yield of ether, for the pivalate esters, varied from 1percent for the 4-methoxy-substituted ester to 20percent for the 3,4,5-trimethoxy-substituted one.The meta effect does not explain these differences; electron transfer converting the radical pair to the ion pair is still an important pathway in the mechanism for ion formation.A quantitative analysis of the yield of the ethers was done in order to obtain the electron-transfer rate constants.This analysis revealed that the yield of the ethers was higher than expected based on previous results for other substituted benzyl acetates.A possible explanation for this discrepancy is that internal return of the radical pair to starting material for the acetate esters is more efficient than for the pivalate esters.Also, the esters 3k and 3l, were prepared to study the effect of electron-withdrawing groups in the meta position.For these esters, the benzylic cleavage reactions were inefficient and an isomerization reaction, the benzvalene rearrangement, was competitive.
