Search results for "cyclic"
showing 10 items of 2439 documents
Roquefortine C occurrence in blue cheese.
2001
Several strains of Penicillium are used for the production of mold-ripened cheeses, and some of them are able to produce mycotoxins. The aims of the research were the determination of roquefortine C and PR toxin in domestic and imported blue cheeses, the identification of the penicillia used as starter, and the investigation of their capacity for producing toxins in culture media. Roquefortine C was always found in the cheeses at levels ranging from 0.05 to 1.47 mg/kg, whereas the PR toxin was never found. The identification of the fungal strains present in the domestic cheeses included Penicillium glabrum, Penicillium roqueforti, and Penicillium cyclopium in the Gorgonzola "dolce" and Peni…
Headspace Volatile Composition of the Flowers of Caralluma europaea N.E.Br. (Apocynaceae)
2009
The volatile constituents of the flowers of Caralluma (Apteranthes) europaea (Guss.) N.E. Br. (Apocynaceae - Asclepiadoideae) from Lampedusa Island were analyzed by headspace method. The analyses allowed the identification and quantification of 41 compounds. The main components were, among the monoterpenoids, terpinolene (23.3%), a-terpinene (19.1%) and linalool (18.4%), whereas, among the carbonylic compounds the major constituents were heptanal (2.0%), octanoic acid (2.4%) and hexanoic acid (1.7%). It is worth to mention the presence of a nitrogen containing compound, indole (0.8%) and of a sulphur containing compound, dimethylsulphide (t). The compounds found in the flowers of C. europea…
7,8‐Dihydroimidazo[1,2‐ c ]pyrimidin‐5(6 H )‐one, ‐5(6 H )‐thione und ‐5(6 H )‐ylidencyanamide
1984
Die Cyclisierung der 4,5-substituierten 2-(2-Aminoethyl)imidazole 5 mit Dimethyl-N-cyandithioimidocarbonat (2), 1,1′-Carbonyldiimidazol (10a) oder 1,1′-Thiocarbonyldiimidazol (10b) ergibt die bisher nicht beschriebenen Titel-Verbindungen 7, 11 und 14. Die 1H- und 13C-NMR-Daten sowie des Verhalten gegenuber Nucleophilen werden beschrieben.
Untersuchungen über das Benzothiiren
1984
Thermolyse und Photolyse von 1,2,3-Benzothiadiazol 10c, liefern die Produkte 11c – 15c. Mit Hilfe der 13C-Markierungstechnik wird gezeigt, das dabei kein intermediares Benzothiiren 1c gebildet wird. Isotopomere Reaktionsprodukte gehen auf H-Verschiebungen zuruck. Durch elektronenziehende Estergruppen in 6-Position wird der Ringschlus zu den substituierten Benzothiirenen 1d, e zwar nicht bei der Thermolyse, wohl aber bei der photochemischen Reaktionsfuhrung ermoglicht. Zum Nachweis dient eine eingehende Untersuchung der bei Thermolyse, Photolyse und auf einem unabhangigen Weg erhaltenen Disulfide 14d, e, bzw. 14d′, e′ und 14d˝, e˝. Die vorliegenden Ergebnisse basieren auf 13C- und 1H-NMR-Mes…
4 H ‐3,1‐Benzoxathiine aus Benzothiet und Carbonylverbindungen
1990
4H-3,1-Benzoxathiines from Benzothiete and Carbonyl Compounds The o-quinoid 8-π electron system 2, generated by thermal ring opening of benzothiete (1) undergoes [8π + 2π] cycloaddition reactions with electron-deficient carbonyl compounds 3. In accordance with the frontier orbital theory, 4H-3,1-benzoxathiines (4) are obtained in a regioselective manner.
Cyano-bridged structures based on [MnIIN3O2-macrocycle)]2+: a synthetic, structural, and magnetic study.
2005
Reactions between the complex [MnII(L)]2+, where L is a N3O2 macrocyclic ligand, and different cyanometalate precursors such as [M(CN)n]m- (M(III) = Cr, Fe; M(II) = Fe, Ni, Pd, Pt) lead to cyano-bridged molecular assemblies exhibiting a variety of structural topologies. The reaction between [MnII(L)]2+ and [FeII(CN)6]4- forms a trinuclear complex with formula [(MnII(L)(H2O))2(FeII(micro-CN)2(CN)4)] x 2MeOH x 10H2O (1) which crystallizes in the triclinic space group P1. The reaction between [MnII(L)]2+ and [M(II)(CN)4]2-, where M(II) = Ni (2), Pd (3), Pt (4), gives rise to three isostructural linear chain compounds with stoichiometry [(MnII(L))(M(II)(micro-CN)2(CN)2)]n and which crystallize …
A Trinuclear Aqua Cyano‐Bridged Ruthenium Complex [{(η 5 ‐C 5 H 5 )(PPh 3 ) 2 Ru(μ‐CN)} 2 RuCl 2 (PPh 3 )(H 2 O)]PF 6 : Synthesis, Characterization a…
2007
The organometallic trinuclear aqua cyano-bridged complex [{(η5-C5H5)(PPh3)2Ru(μ-CN)}2RuCl2(PPh3)(H2O)]PF6 (1), in which the fragment [RuCl2(PPh3)(H2O)] acts as a bridge and an acceptor group between the two terminal cyclopentadienyl ruthenium cyano moieties, was isolated in moderate yield from the reaction of [(η5-C5H5)(PPh3)2RuCN] with [RuCl2(PPh3)3] in THF. To the best of our knowledge, compound 1 is one of the few examples of a trinuclear array of ruthenium fragments bridged by the nitrogen atom of the–C≡N– group (Ru–C≡N–Ru′–N≡C–Ru) with a Ru-coordinated water molecule. The new aqua complex was structurally characterized by FTIR, 1H, 13C, and 31P NMR spectroscopy, mass spectrometry, elem…
Synthesis and Characterization of New Keggin-Based Structure Tungstocobaltates: K9[Co3+W11O39] and its Vanadium Derivatives, K8[Co2+W11V4+O40], K7[Co…
1995
Abstract Good yield synthesis of the potassium salts of four new interrelated : olyoxometalates, [Co3+W11O39]9-(I), [Co2+W11V4+O4]8-(II), [Co2+W11V5+O40]7-(III), and [Co3+W11V5+O40]6-(IV), are reported. The title compounds have been characterized by IR and UV-Vis.-NIR spectroscopies, cyclic voltammetry and magnetic measurements. IR spectra confirm that I has the lacunary structure of an undecatungstate anion, while II through IV have a substituted α-Keggin structure with the vanadium atom located at an octahedral site replacing one tungsten atom. Optical data confirm the oxidation states for both, the Co and V atoms, as formulated for I through IV.
A short synthesis of dimethyl tricyclo[3.3.0.0 3,7 ]octane‐1,5‐dicarboxylate and its 3,7‐dimethyl derivative. A new route to the tricyclo[3.3.0.0 3,7…
1988
Five-step syntheses of dimethyl tricyclo[3.3.0.03,7]octane-1,5-dicarboxylate (13) and its 3,7-dimethyl derivative 14 from the readily available cis-bicyclo[3.3.0]octane-3,7-diones 1 and 2, respectively, are described. The key-step implies the iodine oxidation of the bis-enolate derived from the corresponding dimethyl cis-bicyclo-[3.3.0]octane-3,7-dicarboxylates 11 and 12, thus being developed a new synthetic entry into the tricyclo[3.3.0.03,7]octane skeleton. Also, some attempts to synthesize diester 13 by using known methodology for the synthesis of compounds containing this tricyclic skeleton are described. Eine kurze Synthese von Tricyclo [3.3.0.03,7]octan-1,5-dicarbonsaure-dimethylester…
Straightforward One-Pot Synthesis of New 4-Phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-one Derivatives: X-ray Single Crystal Structure and Hirshfeld Ana…
2022
A straightforward one-pot route for the synthesis of a new 4-phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-one is reported form the direct hydrazinolysis of triketo ester and hydrazine hydrate in ethanol. 4-Phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-one was subjected to aza-Michael addition and N-alkylation on reaction with a set of alkylating agents in the presence of K2CO3. Hydrazinolysis of 4-phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-one ester to hydrazide and conversion of hydrazide to thiosemicarbazide were successful. X-Ray single crystals analysis and 1H, 13C NMR were used for unambiguous structure confirmation. The O…H, N…H, C…N and C…C in 2, and the N…H, …