Monocarboxylic Esters Research Articles

Enzymatic hydrogenation of diverse activated alkenes. Identification of two Bacillus old yellow enzymes with broad substrate profiles

By whole cell transformation, 32 out of 71 strains showed OYEs activity toward maleimide in the first round screening. Among them, a Bacillus strain was identified to be active toward a selection of substrates with different electron-withdrawing groups. Two OYE homologous genes, bac-oye1 and bac-oye2 were cloned from this strain and overexpressed in Escherichia coli BL21(DE3). The recombinant enzyme Bac-OYE2 showed a broader pH range (6.0–10.5), while Bac-OYE1 was so sensitive to pH that it lost most of the enzyme activity below pH 6.0 or above pH 9.0. The reaction temperature exerted similar effects on the activities of both enzymes, but the stability of Bac-OYE2 was more sensitive to the temperature than Bac-OYE1. In addition to α,β-unsaturated aldehydes, ketones, nitroalkenes, and the double activated carboxylic acids, esters, nitriles and cyclic imides, Bac-OYE1 and Bac-OYE2 also exhibited activities toward the “borderline” substrates such as unsaturated lactones, mono carboxylic esters, showing their broader substrate scopes. These enzymes also had excellent enantioselectivity as evidenced by the reductions of several α,β-unsaturated cyclic ketones, α-substituted α,β-unsaturated carboxylic esters and 2-methyl maleimide. For example, methyl 2-acetamidoacrylate was reduced by Bac-OYE1 with >99% conversion and >99% ee.

Ferrocenyl salts as synthons: new ferrocenyl-1,3-dikentones

Reaction of (ferrocenylmethyl)trimethylammonium iodide with the mono-sodium salts of a range of acyclic 1,3-diketones leads smoothly to 2-(ferrocenylmethyl)-1,3-diketones [(C5H5)Fe(C5H4)CH2]CH(COR1)(COR2), but with the corresponding tetrabutylammonium salts deacylation occurs. With the sodium salt of cyclohexane-1,3-dione, disubstitution occurs to give (2,6-dioxocyclohexane-1,1-diyl)bismethyleneferrocene, [(C5H5)Fe(C5H4CH2)]2C[(CO)2(CH2)3]. The lithium salt of acetylferrocene reacts with a range of monocarboxylic esters to provide 1-ferrocenyl-1,3-diketones [(C5H5)Fe(C5H4)]COCH2COR, but simple esters of dicarboxylic acids either do not react, or undergo only monosubstitution.

Überführung von Triazaphospholen in Diazaphosphole durch Acetylenaddition/Nitrileliminierung [1] / Conversion of Triazaphospholes into Diazaphospholes by Acetylene Addition/Nitrile Elimination [1

Abstract Acetylene di-and (less easily) monocarboxylic esters replace nitriles from the 4,5-position of 1,2,4,3-triazaphosphole rings to give carboxyl derivatives of 1,2,3-diazaphospholes, presumably by a cycloaddition/cycloreversion mechanism. In cases with a mobile N-substituent alternatively the loss of N2 seemed feasible, but was normally not observed.

ChemInform Abstract: CONJUGATE ADDITION OF GRIGNARD REAGENTS TO ISOPROPYLIDENE ALKYLIDENEMALONATES

AbstractIn Gegenwart von Kupferchlorid führt die Addition von Grignard‐Verbindungen (II) an die Alkylidenmeldrumsäuren (I) zu den 1,4‐Addukten (III), die sich, wie am Beispiel von (IV) gezeigt wird, in die Monocarbonsäurederivate überführen lassen.

Conjugate Addition of Grignard Reagents to Isopropylidene Alkylidenemalonates

Abstract In the presence of cuprous chloride, the conjugate addition of Grignard reagents to isopropylidene alkylidenemalonates took place rapidly under mild conditions and in high yield. Thus, a new method for the synthesis of isopropylidene tertiary alkylmalonates was developed. Since the resulting isopropylidene alkylmalonates could be hydrolyzed and decarboxylated to the corresponding monocarboxylic acids or subjected to decarboxylative alcoholysis to form the monocarboxylic esters, a new general method for the synthesis of carboxylic acids and esters branched at the β position was provided.

Alkylation of palladium-olefin complexes with monocarboxylic esters

Alkylation of palladium-olefin complexes with monocarboxylic esters

The conservation of oxidative energy in phosphate-free systems. Formation of acyl anhydrides via the oxidation of hydroquinone monocarboxylic esters

1. The free energy released by the oxidation of hydroquinone monoesters or of 6-hydroxychroman-2-ones, using N-bromosuccinimide in glacial acetic acid as oxidant, is trapped and conserved by the formation of acyl anhydrides. For example, by oxidation of 2-methyl-1,4-naphthohydroquinone-1-acetate, acetic anhydride is formed in at least 98% yield. 2. Such observations with model compounds suggest a cyclic scheme for energy conservation in mitochondria, in which ubihydroquinone is postulated to esterify with a protein carboxyl group (without prior carboxyl activation); the resulting ester is oxidized and a labile acid anhydride (or isoenergetic acyl function) is generated within the protein matrix. Reaction of the acid anhydride with inorganic phosphate and, subsequently, with ADP, provides a pathway for the oxidative generation of ATP, by way of a nonphosphorylated high energy intermediate. 3. That the proposed esterification step is feasible in a protein matrix is supported by the demonstration of a facile and complete conversion of coumarinic acid to coumarin at pH 4.

Acyl transfer accompanying the oxidation of monocarboxylic esters of hydroquinones

Benzoyl transfer accompanies the oxidation of monobenzoates of hydroquinones. Oxidising agents used in the present investigation were ceric ion, thallic ion, N-bromosuccinimide, bromine, a high potential quinone, and lithium periodate. Evidence is presented that acylium intermediates are formed in the oxidations with ceric ion: thallic ion oxidations are catalysed by thallous ion, and acyl transfer in these cases appears to require attack of solvent on a thallic ion–substrate complex.

Conservation of oxidative energy. Formation of acyl anhydrides via the oxidation of hydroquinone monocarboxylic esters

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConservation of oxidative energy. Formation of acyl anhydrides via the oxidation of hydroquinone monocarboxylic estersJohn W. Thanassi and Louis Arthur. CohenCite this: J. Am. Chem. Soc. 1967, 89, 22, 5733–5734Publication Date (Print):October 1, 1967Publication History Published online1 May 2002Published inissue 1 October 1967https://doi.org/10.1021/ja00998a060RIGHTS & PERMISSIONSArticle Views64Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (259 KB) Get e-Alerts Get e-Alerts