Absorption Spectra. III. Cyclic β-Diketones

Blout, E. R.; Eager, Virginia W.; Silverman, Dorothy

doi:10.1021/ja01208a009

Cited by 37 publications

(8 citation statements)

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“…2-Brom-1,3-dicarbonyl-Verbindungen 25a und 25d -i (Schema 5): 2-Brom-5,5-dimethylcyclohexan-1,3-dion (25a) [70]; 2-Brom-cyclohexan-1,3-dion (25d) [71]; 2-Brom-5phenylcyclohexan-1,3-dion (25e) [72]; 3-Bromspiro[5.5]undecan-2,4-dion (25f) [73]; 3-Bromtetrahydrofuran-2,4-dion (25g) [74]; 5-Brom-2,2-dimethyl-1,3-dioxan-4,6-dion (25h) [75]; 5-Brombarbitursäure (25i) [76]. Des Weiteren 2-Brommalondialdehyd (37) [34]; 2-Brom-3-oxo-tetrahydrothiophen-1,1-dioxid (41) [37]; 3-Bromcyclohexan-1,2-dion (Enol-Form) (45) [77]; 2,3-Dibrom-5,5-dimethylcyclohex-2-en-1on (48) [41]; Lawessons Reagenz [78] [43]; 2,2-Dibrom-5,5-dimethylcyclohexan-1,3-dion (61) [79]; Kalium-Ethylxanthogenat [45] [80]; Phasen-Transfer-Synthese und Umsetzungen von Na 2 CS 3 [81]; S-Methylmethansulfonothioat (65a; käuflich bei Lancaster; > 98%) [82]; S-(4-Methylphenyl)-4-methylbenzolsulfonothioat (65b) [83]; N,N-Diethyl-4-methylbenzolsulfenamid (67) [84]; Methansulfinylchlorid (78a) [85]; 4-Methylbenzolsulfinylchlorid (78b) (molekular-destilliert) [86].…”

Section: Monodehydrogenierung Bei Aci-reduktonen Im Vergleich Zu 2-thunclassified

Thioreductones and Derivatives (G)

Schank

Bügler

Folz

et al. 2007

Helvetica Chimica Acta

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Thioreductones and DerivativesReplacement of one or two (principally also three) O-atoms in aci-reductones by sulfur leads to the corresponding thioreductones. In the present paper, different methods of their synthesis are discussed. Substitution of the bromo nucleofug in the 2-position of 1,3-dicarbonyl compounds as well as of a 3oxosulfone by selected sulfur nucleophiles is assumed to follow an S RN 1 pathway. Characteristic properties, some typical reactions, and selected derivatives were studied. S-Alkyl-and S-aryl-substituted cyclic 2-thioreductones have been found to be synthons for the preparation of vinylogous reductones (2,3-diacyl-1,4-dihydroxy-1,3-dienes) and of tetraacyl ethylenes as their bis-dehydro products. Helvetica Chimica Acta -Vol. 90 (2007) 1606 2007 Verlag Helvetica Chimica Acta AG, Zürich 1 ) Das ältere Präfix thio (neu: mercapto oder sulfanyl) wird hier aus historischen Gründen für die Diskussion verwendet. Im Exper. Teil sind alle Verbindungen systematisch benannt. auftreten (Schema 2) [16b]. Dieses allgemeine Ergebnis ließ sich durch unabhängige Erzeugung des Thiol/Thion-Gleichgewichts aus entsprechenden Carbonyl-Verbindungen wie 14 mit Lawessons Reagenz (15) [17a] absichern (Schema 2, b). 2.2. Elektrophile Einführung von Schwefel-Substituenten in die 2-Stellung von 1,3-Dicarbonyl-Verbindungen mittels reaktiver Sulfensäure-Derivate. Ebenfalls 1954 hatten Bçhme und Mitarbeiter [18] die acyclischen Thioreduktone 3-Mercaptopenta -2,4-dion (21a) und 2-Mercapto-3-oxobuttersäureethylester (21b) in einer Zweistufensynthese durch Sulfenylierung der Verbindungen 18a,b mit Acetylsulfenylchlorid (19), gefolgt von saurer Alkoholyse der intermediären Acetylthio-Verbindungen 20 in EtOH, hergestellt (Schema 3). Da H-Brücken bei Schwefel-Verbindungen [19] schwächer sind als Schema 2. Erzeugung von Enthiolen und Bildung von Divinylsulfiden aus dem resultierenden Thiol/ Thion-Gleichgewicht unter Abspaltung von H 2 S [16b] Helvetica Chimica Acta -Vol. 90 (2007) 1609 Schema 1. Thiolierung von Dimedon (9) unter Willgerodt -Kindler-Bedingungen bei Sauerstoff-Verbindungen, erklärt sich die leichte Destillierbarkeit der Flüssigkeiten 21a,b mçglicherweise über die Chelatformel 21E (E ¼ Enol, K ¼ Keto). Für den ersten Schritt in Schema 3 benutzten Menichetti und Mitarbeiter [20] das Phthalimidosulfenylchlorid 22 zur Einführung des Schwefels in reaktive Methylen-Verbindungen (Schema 4).Anstelle der sauren Solvolyse im zweiten Reaktionsschritt führten sie jedoch eine Basen-katalysierte Eliminierung von Phthalimid unter Bildung der Thion-Funktion im 1,3-Dioxo-2-thion 24 durch, dessen Cycloadditionsreaktionen in situ studiert wurden, weil sich die freie Verbindung nicht isolieren ließ.Einige Jahre zuvor waren entsprechende Reaktionen mit einer Reihe cyclischer Thione (u.a. analog zu 24) durchgeführt worden, die zuvor mit Dithiobisphthalimid (DBP) oder mit Dithiobissuccinimid (DBS) auf vergleichbare Weise erzeugt worden waren [21]. Über Cycloadditionen von am Thion-Schwefel oxygenierten Vertretern berichteten Menichet...

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Section: Monodehydrogenierung Bei Aci-reduktonen Im Vergleich Zu 2-thunclassified

Thioreductones and Derivatives (G)

Schank

Bügler

Folz

et al. 2007

Helvetica Chimica Acta

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“…The product showed much more intense absorption at pH 10 than at pH 7n5 and shifted its absorption maximum from 280 nm at pH 7n5 to 300 nm at pH 10. Such a spectral property is typical of a β-diketone compound (Blout et al, 1946 ;Silverstein et al, 1991). The oxidized PVA was isolated from the reaction mixture by addition of trichloroacetic acid at a final concentration of 1 %, followed by standing for 5 min on ice, centrifugation at 30 000 g for 5 min at 4 mC, dialysis of the supernatant against water, and freezedrying.…”

Section: Cleavage Of the Pva Molecule By Pvadh And Ophmentioning

confidence: 99%

The gene pvaB encodes oxidized polyvinyl alcohol hydrolase of Pseudomonas sp. strain VM15C and forms an operon with the polyvinyl alcohol dehydrogenase gene pvaA The DDBJ accession number for the sequence reported in this paper is AB008494.

et al. 2000

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A 57 kbp SphI fragment containing the polyvinyl alcohol (PVA) dehydrogenase gene pvaA and its 19 kbp 5'-flanking region was cloned from the PVAdegrading bacterium Pseudomonas sp. VM15C. The pvaB gene, encoding oxidized PVA hydrolase, was found in the region upstream of pvaA. Sequence data and expression studies indicated that pvaA and B constitute an operon in the order pvaBA. The pvaB gene encoded a protein of 379 amino acid residues (40 610 Da), and a lipoprotein signal sequence and the lipase consensus sequence, Gly-X-Ser-X-Gly, characteristic of the active-site serine region in serine hydrolases, were detected in the deduced amino acid sequence. The pvaB product with the pvaA product constituted an enzyme system for the cleavage of PVA molecules. The pvaA product introduced β-diketone groups into the PVA molecule, and the pvaB product hydrolysed these β-diketone groups in oxidized PVA. The pvaB product also hydrolysed 4,6-nonanedione at a low rate, but not acetylacetone or 5-nonanone. It was completely inhibited by PMSF and was concluded to be a serine hydrolase. There were no proteins showing high similarity to the pvaB product in the databases, but minor similarity to a number of serine hydrolases including polyhydroxyalkanoate depolymerases was apparent.

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“…Monocyclic 1,3-diketones such as the dihydroresorcinol derivatives 1,3-cyclohexanedione and 5,5-dimethyl-l ,3-cyclohexanedione (dimedon), on the other hand, have been found to differ from their open-chain counterparts in a number of instances where chelation might be expected. The contrast between the open-chain and cyclic diketones has been made in discussions of acidity (26, 148, 153b, 167, 186), of the effect of solvents on the keto-enol equilibrium (9), and of absorption spectra (28,133), and it has been pointed out that, although enolization can occur, steric factors prevent chelation of the enol form of the cyclic 1,3-diketones. In studying the effect of structure on absorption spectra, Blout, Eager, and Silverman (28) examined dimedon and 2-ethyI-4-n-propyl-1,3-cyclopentanedione.…”

Section: Lxxxva Lxxxvb Lxxxvcmentioning

confidence: 99%