Hydration constants of pyridinecarboxaldehyde N-oxides

Okano, Valkiria; Toma, Henrique E.; Amaral, Luciano

doi:10.1021/jo00318a036

Cited by 8 publications

(2 citation statements)

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“…An investigation of the hydration equilibrium of 4-pyridine carboxaldehyde by 1 H NMR-spectroscopy showed that the presence of NMO (containing 1 equiv of water of crystallization) leads to a considerable shift toward the hydrate (Figure ). Notably, this previously unknown effect is irrespective of the solvent used. In acetonitrile, dichloromethane, or DMF, one third of the aldehyde is converted to the hydrate if NMO·H 2 O is added (Table ).…”

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confidence: 92%

TPAP-Catalyzed Direct Oxidation of Primary Alcohols to Carboxylic Acids through Stabilized Aldehyde Hydrates

2011

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confidence: 92%

TPAP-Catalyzed Direct Oxidation of Primary Alcohols to Carboxylic Acids through Stabilized Aldehyde Hydrates

2011

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“…Brusatol (I) was obtained either by treating bruceoside-A (X) with 3 N HzS04methanol (1:l) to hydrolyze the glycosidic linkage (7,8) or directly from the chloroform extract of B. jauanica. Bruceantin (11) and bruceolide (111) were obtained from bruceoside-A by a synthetic procedure (9). The chemical synthesis, purification, and physical characteristics of a series of brusatolyl and bisbrusatolyl esters (IV-VI) (lo), two bisbruceantinyl esters (VII and VIII) (11) and tetrahydrobrusatol (IX) (10) have been reported previously by this laboratory.…”

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confidence: 99%

Anti-inflammatory Agents III: Structure–Activity Relationships of Brusatol and Related Quassinoids

Hall

Lee

Imakura

et al. 1983

Journal of Pharmaceutical Sciences

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Synthese und Eigenschaften von Makrocyclen aus Resorcinen sowie von entsprechenden Derivaten und Wirt‐Gast‐Komplexen

Schneider

1994

Chem. Ber.

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Structural variations of the metacyclophanes obtained from the condensation of resorcinol with aldehydes RCHO are described, mostly based on the stereoisomer with all R in cis configuration. The basic tetraphenolate (with R = CH3, la) shows a cone-conformation as evident e.g. from vicinal 13C-C-C-'H coupling constants. Substituents R' in the 2position of the phenyl rings at the upper rim of the macrocycle are either introduced with the resorcinol derivative used (R' = CH3, COOH), or by Mannich reactions after cyclization (R' = CH2NR$), which partially lead to intermediate oxacine formation. Acid-base properties are evaluated with potentiometric and NMR-shift titrations. Mannich products from amino acids such as proline, which are formed without racemization, show no pK differences for the groups at the four equivalent phenyl rings, but three distinct pK values for the deprotonation of OH, COOH, and +NH3 substituents; the pK of the latter is two units lower than in proline itself as it is involved in hydrogen bridging. Complexation constants K of such derivatives with Fe3+, Cu2+, and ZnZt show the expected increase with metal ion acidity; they are increased by a power of 5 in comparison to proline. Complexation constants and complexation-induced NMR shifts (CIS values) Synthese funktionalisierter Derivate Kondensation substituierter Resorcin-und Aldehydkomponenten: In Analogie zu den von Hogberg[2a,b] beschriebenenUmsetzungen von Acetaldehyd und Benzaldehyd rnit Resorcin fuhrte der Einsatz von 4-Phenylacetaldehyd bzw. 4-Phenylbenzaldehyd zu den Verbindungen 3a, b und 4a mit ausgepragt lipophilen Zentren an der Molekulbasis. Die Umsetzung von Acetaldehyd rnit 2,6-Dihydroxybenzamid als Resorcinkomponente ergab keine definierten cyclischen Produkte, was auf die desaktivierende Wirkung des Saureamidsubstituenten (-I-und -M-Effekt), die sich ungunstig auf die Sequenz von aromatischen Substitutionsreaktionen zur Bildung des cyclischen Tetramers auswirkt [6,71, zuriickgefuhrt werden kann. In Ubereinstimmung damit konnte die Kondensation rnit 2,6-Dihydroxybenzoesaure erst dann erfolgreich durchgefuhrt werden, wenn diese Resorcinkomponente in dissoziierter Form, also als Carboxylat rnit einer im Vergleich zur Saure erhohten Elektronendichte an den Kohlenstoffatomen des aromatischen Rings, an der Reaktion teilnahm. Dazu wurde die Kondensation ohne Mineralsaurezusatz durchgefuhrt, wodurch 2,6-Dihydroxybenzoesaure selbst als Protonenlieferant agierte. Als Reaktionsprodukte konnten die Makrocyclen 8 a und 8 b isoliert werden.

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Hydration constants of pyridinecarboxaldehyde N-oxides

Cited by 8 publications

References 1 publication

TPAP-Catalyzed Direct Oxidation of Primary Alcohols to Carboxylic Acids through Stabilized Aldehyde Hydrates

TPAP-Catalyzed Direct Oxidation of Primary Alcohols to Carboxylic Acids through Stabilized Aldehyde Hydrates

Anti-inflammatory Agents III: Structure–Activity Relationships of Brusatol and Related Quassinoids

Synthese und Eigenschaften von Makrocyclen aus Resorcinen sowie von entsprechenden Derivaten und Wirt‐Gast‐Komplexen

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