Acid Rearrangement Research Articles

ChemInform Abstract: STUDIES IN THE USNIC ACID SERIES. V. THE BASE CATALYZED USNIC ACID‐ISOUSNIC ACID REARRANGEMENT. PART III. (‐)‐USNIC ACID ISOMETHOXIDE MONOACETATE

AbstractDas aus (+)‐Usninsäure (+)‐(Ia) zugängliche Diacetat (+)‐(Ib) gibt beim Umsetzen mit metha‐ ‐ nolischem HCl ein Epimerengemisch des Äthers (‐)‐(II), der zu der Isoxazonlousninsäure (+)‐(IIIa) (Epirnerengemisch) cyclisiert wird.

Studies in the usnic acid series. V. The base catalyzed usnic acid – isousnic acid rearrangement. Part III. (—)-Usnic acid isomethoxide monoacetate

Further studies on the base catalyzed usnic acid – isousnic acid rearrangement process clarify the situation concerning (−)-usnic acid isomethoxide monoacetate (7). This substance is now shown to be a mixture of the two possible C4a epimers. These and previous data allow a mechanism to be proposed for this interesting rearrangement.

Aromatic sulphonation. Part 56. The rearrangement of phenylsulphamic acid to aniliniumsulphonic acids in concentrated sulphuric acid: evidence for an intermolecular reaction pathway

Phenylsulphamic acid in a large excess of 96–100% H2SO4 at 25° yields both orthanilic and sulphanilic acid intermolecularly by initial C-sulphonation and subsequent N-desulphonation. This conclusion is based on (i) the u.v. and n.m.r. observation in ca. 100% H2SO4 of o- and p-sulphophenylsulphamic acid as reaction intermediates and (ii) the dependence of both the rate of sulphonation of phenylsulphamic acid and of the isomer distribution of the aniliniumsulphonic acid products on the sulphuric acid concentration. The reacting and the major substrates were identified by kinetic, product, and protonation studies to be PhNHSO3H and PhNH2SO3– respectively. The ionization PhNH3SO3–⇌ PhNHSO3–+ H+ has an apparent pKa value of –2.03, based on the Ho acidity function.

Photochemical equivalent of a benzilic acid rearrangement and related conversions

Irradiation of a 2-benzyl-2-hydroxybenzo[b]furan-3(2H)-one in acetone–water results in the equivalent of a benzilic acid rearrangement of the aryl benzyl α-diketone formed from homolysis of the heterocycle, to give the 3-benzyl-3-hydroxybenzo[b]furan-2(3H)-one analogue.

Metabolites from microorganisms. Conocandin, a new fungi-static antibiotic (author's transl)

Metabolites from Microorganisms. 160th Communication. Conocandin, a new Fungistatic Antibiotic.From a strain of Hormococcus conorum (SACC. ET ROUM.) ROBACK A 32′287, conocandin, a novel type C18‐fatty acid with high and specific in vitro fungistatic activity was isolated by means of counter current distribution and silicagel chromatography. The antibiotic is a viscous oil with the molecular formula C18H30O3. It is characterized by IR. and NMR. spectra, ester derivatives and the products of acid rearrangement and ozonolytic degradation. The structure of (E)‐2‐methylidene‐10‐methyl‐trans‐3,4‐epoxy‐9‐hexadecenoic acid (1) is proposed.

Conversion of dehydroascorbic acid to a branched hexaric acid in neutral and alkaline aqueous solution

Dehydroascorbic acid is shown to be converted to 2-( threo-1,2,3-trihydroxypropyl)tartronic acid in aqueous alkaline solutions. The structure of the acid was determined by mass spectrometry of its acyclic Me 3Si derivative. Mass spectrometric and chromatographic data are compared with those of related compounds. The acid is formed by a benzilic acid rearrangement of the intermediate 2,3-hexodiulosonic acid. The rate of formation at 38°C was studied quantitatively by glc. It increases at increased alkalinity but is significant even at physiological pH. The presence of oxygen does not substantially influence the reaction.

ChemInform Abstract: REARRANGEMENT OF MALEURIC ACID

Chemischer InformationsdienstVolume 7, Issue 16 Preparative Organic Chemistry ChemInform Abstract: REARRANGEMENT OF MALEURIC ACID C. O'MURCHU, C. O'MURCHUSearch for more papers by this author C. O'MURCHU, C. O'MURCHUSearch for more papers by this author First published: April 20, 1976 https://doi.org/10.1002/chin.197616150Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume7, Issue16April 20, 1976 RelatedInformation

Studies of the Isomerization of Unsaturated Carboxylic Acids. II. The Thermal Rearrangement of Citraconic Acid to Itaconic Acid in Aqueous Solutions

Abstract The thermal reaction of citraconic acid (2) in water gives a mixture of products similar to that obtained from itaconic acid (1) in water. After 22 h at 170 °C, the equilibrium composition about 74%, 18%, and 8% 1, 2, and mesaconic acid respectively. At the optimum conditions (170 °C for 3 h), the yield of 1 is 65%. The mechanism of the reaction is discussed.

Formation of 1,4-Anhydro-3-deoxypentitol-2-carboxylic Acids by Alkaline Degradation of Cellulose.

An anhydroisosaccharinic acid obtained in large amounts by end-wise degradation of cellulose in alkaline media, and in small amounts in hydrolysates of cellulose, has been identified as a 1,4-anhydro-3-deoxypentitol-2-carboxylic acid (3-hydroxy-5-(hydroxymethyl)oxolane-3-carboxylic acid). Structural evidence was obtained by GC-MS studies of the compounds (as Me3Si derivatives) obtained on degradation of the acid to 1,4-anhydro-3-deoxypentitol by reduction of the methyl ester followed by periodate oxidation and borohydride reduction. In aqueous alkali, the acid is likely to be formed from a dicarbonyl precursor by benzilic acid rearrangement.

Novel rearrangement of 6β,19-oxido-2,17-dihydroxyandrosta-1,4-dien-3-one

Under benzilic acid rearrangement conditions and acidic work-up, 6β,19-oxido-2,17-dihydroxyandrosta-1,4-dien-3-one ( 1) underwent unusual, extensive rearrangement affording a furopyranone ( 3) in high yield. This product was the result of B-ring contraction, double bond isomerization and benzilic acid rearrangement of 1, followed by acid catalyzed cyclization of the carboxy intermediate with the vinyl ether portion of the molecule. Alternatively, alkylation of the barium salt ( 2) of the reaction mixture with dimethyl sulfate in dimethyl formamide gave a carbomethoxy dihydrofuran derivative ( 6). Oxidation of the furopyranone ( 3) with Jones reagent produced a furanone derivative ( 5) formed via hydrolysis and oxidative-decarboxylation. The complex molecular structures of these rearrangement products were determined through extensive analysis of NMR spectra utilizing double resonance and Eu(FOD) 3 shift reagent. The structural assignments are supported by a proposed mechanism of formation.

Dicarboxylic Acids Produced by Oxygen-Alkali Treatment of Birch Xylan.

C-(2-Hydroxyethyl)tartronic acid is predominant among the dicarboxylic acids and its formation in 12 % yield makes it a major product from xylan. The structure indicates that it is formed from terminal, oxidized xylose units by beta-elimination at C-4 and subsequent benzilic acid rearrangement. It is proposed that 2-ulosonic acid end-groups or ulosono-1,5-lactone end-groups, related in structure to ascorbic acid, are formed as precursors.

Reaction of biguanides and related compounds. XIII. Benzilic acid rearrangement. The reactions of 1,2-cyclohexanedione and 9,10-phenanthrenequinone with arylbiguanides and N-amidino-O-alkylisoureas.

Reaction of biguanides and related compounds. XIII. Benzilic acid rearrangement. The reactions of 1,2-cyclohexanedione and 9,10-phenanthrenequinone with arylbiguanides and N-amidino-O-alkylisoureas.

Diterpenoids. XXXIV. Stereochemistry on the rearranged compound (benzilic acid rearrangement) of methyl 6,7-dioxo-5.ALPHA.,10.ALPHA.-podocarpa-8,11,13-trien-15-oate.

Stereochemistry of the hydroxy diacid (III), which was obtained by the benzilic acid rearrangement of the dioxo ester (II) derived from l-abietic acid (I), was determined uneqivocally. Moreover, the rearranged compounds (III and IX) were concluded to have a nonsteroidal form.

Alkalische Spaltung und Benzilsäureumlagerung von 1,2,3‐Triketonen. 29. Mitt. über Reduktone und Tricarbonylverbindungen [1

Under the conditions of the benzilic acid rearrangement diaryl und dialkyl 1,2,3‐triketones RCOCOCOR′ show two reactions: (1) Migration of RCO towards the more electronegative or less hindered CO group, yielding an α‐hydroxy‐β‐ketoacid which can undergo secondary reactions, and (2) direct cleavage between adjacent carbonyl groups forming RCOOH and R′CHOHCOOH, RCO being more electronegative or less hindered than R′CO. The balance between these reactions depends upon the steric and electronic properties of R and R′.

Umlagerung und Spaltung von α, β‐Dioxopropionsäureestern in alkalischem Milieu. 28. Mitt. über Reduktone und Tricarbonylverbindungen [1

The behaviour of α,β‐dioxopropionic acid derivatives of the type RCOCOCOX (R = phenyl, p‐substituted phenyls, CF3, mesityl; X = OC2H5, NH2) was investigated under benzilic acid rearrangement conditions. Nearly all compounds were cleaved by alkali to give the corresponding acids RCOOH and glyoxylic acid. Only the sterically hindered ethyl β‐mesityl‐α,β‐dioxopropionate underwent rearrangement (after hydrolysis of the ester group); it was shown by 14C‐labelling that the carboxylate group migrates to the β‐carbonyl group.

Structure of the primary acid rearrangement product of reduced nicotinamide adenine dinucleotide (NADH).

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure of the primary acid rearrangement product of reduced nicotinamide adenine dinucleotide (NADH)Norman J. Oppenheimer and Nathan O. KaplanCite this: Biochemistry 1974, 13, 23, 4675–4685Publication Date (Print):November 1, 1974Publication History Published online1 May 2002Published inissue 1 November 1974https://doi.org/10.1021/bi00720a001RIGHTS & PERMISSIONSArticle Views422Altmetric-Citations50LEARN 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 (1 MB) Get e-Alerts Get e-Alerts

A NEW SYNTHETIC METHOD FOR β-SUBSTITUTED Δα,β-BUTENOLIDES

Abstract α-Phenylsulfinyllactones 2 underwent the Pummerer rearrangement and subsequent elimination of acetic acid by treating with hot acetic anhydride to give α-phenylthiobutenolides 4. Conjugate addition reaction of 4 with organocopper reagents or malonic ester followed by oxidation to sulfoxides and pyrolysis afforded β-monosubstituted or β,γ-disubstituted butenolides 6 in moderate overall yields.

Application of Chemical Reactions on Thin-layer Chromatoplates. IV. Triterpenes

Abstract Some specific reactions of triterpenoids had been performed on thin-layer chromatoplates. The reactions conducted were: oxidation with oxygen in K-t-butoxide, benzilic acid rearrangement, decarboxylation with lead tetraacetate, Wolff-Kischner reduction, reduction with sodium borohydride, reduction with lithium aluminium hydride, oxidation with chromium trioxide in pyridine and in acetic acid, oxidation with manganese dioxide in chloroform, methylene chloride and isopropyl alcohol, insertion of an oxygen atom in ring A of triterpenoids by the formation of acid anhydride and reduction by a modified Clemmensen method.

Stereochemical Studies on the Nuclear Alkylation of Phenols with 1-Phenylethyl Chloride and the Acidic Rearrangement of the 1-Phenylethyl Ethers of Phenols in the Phenolic Solvents

Abstract Phenolyses of optically active 1-phenylethyl chloride were carried out in phenol (50°C), p-cresol (100°C), p-chlorophenol (100°C), and 2,6-xylenol (100°C in the presence of variable concentrations of the sodium salts of the respective phenols or triethylamine; the distributions (%) for the O- and C-alkylation products and the net steric courses (α%) for each product were examined. The distribution and the steric course which were graphically extrapolated to the zero base concentration indicated that, if the influence of the liberated hydrogen chloride was excluded, in the phenolyses without an added base the major products are the 1-phenylethyl ethers of the respective phenols with net retained configurations and the minor products are the o-and p-1-phenylethylated phenols with net inverted configurations. The hydrogen chloride rearrangement of the optically active 1-phenylethyl ethers of the respective phenols proceeded rapidly to give o-1-phenylethylated phenols with predominantly retained configurations (for phenol, p-cresol, and p-chlorophenol) and p-1-phenylethylated phenols with net inverted configurations (for phenol and 2,6-xylenol) in the respective phenol–benzene (1:1 by wt) solvents. The p-toluenesulfonic acid rearrangement of 1-phenylethyl phenyl ether-18O proceeded to give o- and p-1-phenylethylphenols with partial loss of the oxygen-18 atom in the phenol–benzene (1:1 by wt) solvent, indicating the coexistence of the intermolecular course for the acidic rearrangement in the phenolic solvents. From these findings, it is concluded that the formation of the ortho-alkylates with retention of configuration, experimentally observed in the respective phenolyses without an added base, is attributed not to the direct retentive alkylation of the phenols, but to the rapid rearrangement of the 1-phenylethyl ethers with net retention of configuration, caused by the hydrogen chloride liberated in the SN1-phenolysis of 1-phenylethyl chloride in the respective phenolic solvents.

Bicyclosesquiphellandrene and 1-epibicyclosesquiphellandrene: Two new dienes based on the cadalene skeleton

Two new sesquiterpene hydrocarbons, bicyclosesquiphellandrene and 1-epibicyclosesquiphellandrene have been isolated from Piper cubeba oil and Ocimum basilicum oil respectively. Their structures were elucidated spectroscopically and their stereochemistry by acid rearrangement and hydrogenation studies.