Acidität, Infrarot‐ und Kernresonanz‐Spektren substituierter γ‐Ketocarbonsäuren bzw. ihrer Pseudosäuren

Pascual, C.; Wegmann, Dorothée; Gräf, Ulrich; Scheffold, Frank; Sommer, Paul; Simon, W.

doi:10.1002/hlca.19640470128

Cited by 23 publications

(9 citation statements)

References 13 publications

(2 reference statements)

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“…Copies may be obtained through The Managing Editor, International Union of Crystallography, 5 Abbey Square, Chester CH1 2HU, England. proton NMR and solid-state IR spectra (Pascual et al, 1964). Its isomer 5-oxopentanoic acid (1) has been synthesized as an oil which crystallizes to form a solid with m.p.…”

Section: Substituted Aliphaticmentioning

confidence: 99%

“…The parent cyclic acids were named 'pseudos~iure' (pseudoacid)., For the 4-ketoacids, the cyclic form of levulinic acid (4oxopentanoic acid) was recognized more than a century ago as the potential intermediate in its acid-promoted dehydration to a-angelica lactone (Bredt, 1886). In solution, levulinic acid exists in the open form, although substitution at the positions between the carbonyls apparently shifts the solution equilibria toward the cyclic forms (Pascual et al, 1964;Claeson & Thalen, 1967). The cis-unsaturated analogs, such as mucochloric acid (Mowry, 1950), penicillic acid (Birkinshaw et aL, 1936) and 4-oxypentenoic acid derivatives (Sheffold & Dubs, 1967) have open-cyclic equilibria which favor the cyclic forms.…”

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confidence: 99%

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Pseudoacids. I. 4- and 5-Oxoacids

Valente¹,

Fuller²,

Ball³

1998

Acta Crystallogr Sect B

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Certain 4- and 5-oxoacids may exist in their cyclic lactol (or pseudoacid) forms. These commonly occur in compounds with proximate carboxylic acid and carbonyl (aldehyde or ketone) functions for the formation of five- or six-membered rings. Examples include trans-2,3-disubstituted aliphatic, (Z)-2,3-olefinic and o-disubstituted aromatic acids. Crystal structures of compounds in these categories are reported: trans-4-methyl-3-oxo-6-hydroxytetrahydropyran-3-carboxylic acid (6), monoclinic, C2/c, a = 25.412 (5), b = 6.291 (1), c = 10.757 (2) A, beta = 104.84 (3) degrees; penicillic acid (7), 4-methoxy-5-hydroxy-5-(2'-propenyl)dihydrofuran-2-one, tetragonal, P4(2)/n, a = b = 15.83 (2), c = 7.016 (11) A; mucochloric acid (8), (Z)-3,4-dichloro-5-hydroxydihydrofuran-2-one, triclinic, P1, a = 6.227 (5), b = 8.085 (5), c = 12.369 (9) A, alpha = 99.50 (5), beta = 102.38 (6), gamma = 90.29 (6) degrees; 2-methanoylbenzoic acid (9), 3-hydroxy-1-(3H)-isobenzofuranone, monoclinic, P2(1), a = 4.006 (1), b = 11.489 (2), c = 7.347 (1) A, beta = 97.50 (3) degrees; 2-ethanoylbenzoic acid (10), 3-hydroxy-3-methyl-1-(3H)-isobenzofuranone, orthorhombic, P2(1)2(1)2(1), a = 5.199 (6), b = 9.651 (14), c = 15.950 (17) A; 2-(2'-oxoethyl)benzoic acid (11), 3-hydroxy-3,4-dihydroisobenzopyran-1-one, monoclinic, P2(1)/n, a = 4.651 (3), b = 11.886 (7), c = 14.312 (11) A, beta = 90.86 (6) degrees. These compounds also exist in the cyclic forms in chloroform solution. A trimeric cyclic trioxane structure, analogous to paracetaldehyde, is confirmed as the solid form of 5-oxopentanoic acid (1), triclinic, P1, a = 5.640 (4), b = 8.571 (8), c = 18.962 (13) A, alpha = 78.68 (6), beta = 84.34 (5), gamma = 80.38 (6) degrees. In solution (NMR), mixtures of the open aldoacid, trimeric acid and cyclic pseudoacid exist. In both furanoid and pyranoid pseudoacids, endocyclic lactol C-O bond lengths are lengthened (1.46-1.48 A), while the exocyclic C-O(H) bonds are shortened (1.38 A). Pseudoacids commonly form hydrogen-bonded chains linking the lactol hydroxy and carbonyl groups, but 3-hydroxy-3,4-dihydroisobenzopyran-1-one forms distinctive hydrogen-bonded dimers.

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Section: Substituted Aliphaticmentioning

confidence: 99%

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confidence: 99%

Pseudoacids. I. 4- and 5-Oxoacids

Valente¹,

Fuller²,

Ball³

1998

Acta Crystallogr Sect B

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“…For consistency, the endocyclic system may be taken to be the open 2-acylbenzoic acids. Estimation of the pKa's may be further complicated by the effect of the normal-pseudoacid equilibrium (Pascual et al, 1964). ground state structure depend on the varying disparity of the comparative leaving-group tendencies.…”

Section: Oo Cmentioning

confidence: 99%

“…In solution, contributions to the oxoacid open ~ cyclic equilibrium (Ke) by a cyclic pseudoacid act to diminish the observed pK,, by removing the more acidic component. For o-acylbenzoic acids (Bowden & Taylor, 1971) and aliphatic 4-oxoacids (Pascual et aL, 1964;Sheffold & Dubs, 1967), K~ ranges from <6 to >100 and depends on the solvent. The implied pK~ reduction of <1 to >3 pK units follows from a modification of the observed pKa by the factor -log(1 + Ke).…”

Section: Oo Cmentioning

confidence: 99%

“…Oxoacids with structures bringing the carboxyl and aldehyde/ketone groups into proximity are more likely to form cyclic pseudoacid forms in solution and in the solid state (Langlois & Wolff, 1948: Mowry, 1950. Therefore, 4-oxopentanoic acid (levulinic acid) is entirely in its open form in solution at room temperature (Pascual et al, 1964). Dehydration of levulinic acid has long been known to produce otangelicalactone [5-methyl-2(3H)-furanone (Wolff, 1885;Bredt, 1886)] putatively through the lactol (pseudoacid).…”

Section: Introductionmentioning

confidence: 99%

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Pseudoacids. II. 2-Acylbenzoic Acid Derivatives

Valente¹,

Martin²,

Sullivan³

1998

Acta Crystallogr Sect B

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Kondensierte Indole aus 2‐Chlorindolaldehyd‐(3)

Schulte¹,

Reisch²,

Stoess³

1972

Archiv der Pharmazie

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Aus 2-Oxindolen lassen sich mit dem Vilsmeier-Reagens 2Chlorindol-3aldehyde darstellen, wahrend 2-bzw. 3-Pyrrolone zu 2-bzw. 3-Hydroxypyrrolaldehyden fuhren. Unter gleichen Bedingungen reagieren Succinimid, N-Phenylsuccinimid und 1 -Phenyl-2.3dimethylpyrrolon-(S) nicht. Aus 2Chlorindolaldehyd-(3) sind durch Umsetzung mit bifunktionellen Verbindungen kondensierte Indolderivate zuginglich.Indole Derivatives from 2-Chloroindole3-aldehydes 2Chloroindole-3-aldehydes can be obtained from 2-oxindoles by Vilsmeier-reaction, while 2 -and 3-pyrrolones yield 2-and 3-hydroxypyrrolealdehyde respectively. Succinimide, N-phenylsuccinimide and l-phenyl3,Mimethyl-pyrrol-5-one do not react under the same conditions. Indole derivatives are accessible by reaction of 2-cNoroindole-3-aldehyde with bifunctional compounds.2-Chlorindolaldehyde-(3) und 2(3)-Chlorpyrrolaldehyde-(3(2)) miifiten als &Chlor-vinyl-aldehyde sehr reaktionsfahig und als Ausgangssubstanzen fir die Synthese rnehrkerniger Heterocyclen geeignet sein, denen unter arzneimittelsynthetischem Aspekt Bedeutung zukommt. Diese PChloraldehyde sollten durch Chlorformylierung von Oxindolen und Pyrrolonen zugiinglich sein.Oxindole lassen sich mit dem Vilsmeier-Reagens in befriedigenden Ausbeuten zu 2Chlorindolaldehyden-(3) umsetzen, worauf wir schon f r~e r hingewiesen haben'). Auf dem gleichen Wege lassen sich die Verbindungen 1 und 2 darstellen. c, H5 2Bei den Pyrrolonen verlief diese Reaktion nicht immer in der angestrebten Weise. Nach Einwirkung des Vilsrneier-Reagenzes auf 2-Methyl-3carbathoxy-pyrrolon-(4) (3) konnen zwei Substanzen isoliert werden. In geringer Ausbeute entsteht 2-Methyl-3-carbathoxy4-chlor-pyrrolaldehyd-(S) (4) neben 2-Methyl-3-carbathoxy-4-hydroxy-

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Acidität, Infrarot‐ und Kernresonanz‐Spektren substituierter γ‐Ketocarbonsäuren bzw. ihrer Pseudosäuren

Abstract: 2134, Die Standardabweichung in der Bestimmung der pK&cS-Werte betragt 0,07 pK&-Einheiten (95% Sicherheitsschwelle) : vgl. s).

Cited by 23 publications

References 13 publications

Pseudoacids. I. 4- and 5-Oxoacids

Pseudoacids. I. 4- and 5-Oxoacids

Pseudoacids. II. 2-Acylbenzoic Acid Derivatives

Kondensierte Indole aus 2‐Chlorindolaldehyd‐(3)

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