Search results for "Enone"
showing 10 items of 320 documents
Oligomere aus gleichsinnig angeordneten Chalkon-Bausteinen
1999
The cross-conjugated oligomers 1a–d, which contain up to eight alternately arranged chalcone building blocks, were prepared by stereoselective condensation reactions of formyl and acetyl components. The synthetic sequence started with 1,4-dibromo-2,5-dipropoxybenzene (2). Bouveault reactions with DMF and DMA yielded the aldehydes 3 and 6 and the ketones 7 and 10. After the protection of the carbonyl group (3 4 and 7 8), a further Bouveault reaction led to monoprotected dialdehyd 5 and diketone 9, respectively. Repetitive condensation reactions starting with the acetophenone derivative 11 and 5 furnished the aldehyde 12, the ketone 13 and the aldehyde 14. In the final step the target compoun…
Verbindungen mit potentiell positiv inotroper Wirkung, 2. Mitt. Synthese von 3,4-Dihydro-2-[(3-oxo-1-cyclopenten-1-yl)amino]-1(2H)-phenanthron und 3-…
1984
Die Darstellung der Titelverbindungen aus 1,3-Cyclopentandion und 2-Amino-3,4-dihydro-1(2H)-phenanthron bzw. 2-Amino-1,2,3,4-tetrahydro-1-phenanthrol wird beschrieben. Compounds with Potentially Positive Inotropic Activity, II: Synthesis of 3,4-Dihydro-2-[(3-oxo-1-cyclopenten-1-yl)amino]-1(2H)-phenanthrone and 3-(1,2,3,4-Tetrahydro-1-hydroxy-2-phenanthrylamino)-2-cyclopentenone The synthesis of the title compounds from 1,3-cyclopentanedione and 2-amino-3,4-dihydro-1(2H)-phenanthrone and 2-amino-1,2,3,4-tetrahydro-1-phenanthrole is described.
Triplet stabilization for enhanced drug photorelease from sunscreen-based photocages
2021
[EN] Recently, sunscreen-based drug photocages have been introduced to provide UV protection to photoactive drugs, thus increasing their photosafety. Here, combined experimental and theoretical studies performed on a photocage based on the commercial UVA filter avobenzone (AB) and on the photosensitizing non-steroidal anti-inflammatory drug ketoprofen (KP) are presented unveiling the photophysical processes responsible for the light-triggered release. Particular attention is paid to solvent stabilization of the drug and UV filter excited states, respectively, which leads to a switching between the triplet excited state energies of the AB and KP units. Most notably, we show that the stabiliz…
Occurrence and risk assessment of zearalenone in flours from Portuguese and Dutch markets
2014
The occurrence of zearalenone (ZEA) in different flours for human consumption, from the Portuguese and Dutch markets, was evaluated. Good analytical performance was obtained through extraction with acetonitrile:water (90:10), clean-up with immunoaffinity columns, and detection and quantification by liquid chromatography-fluorescence detection. ZEA levels were determined in 48 samples to verify the compliance with the maximum permitted levels by European legislation. Two flour samples from Portugal exceeded the maximum limit established by EC. A major presence and levels in maize flours was shown. Coimbra (Portugal) and Utrecht (The Netherlands) samples showed that 37.5% of the samples were …
Loss of a freshwater copepod species from El Junco Lake, Galápagos following the introduction and eradication of the Nile tilapia
2021
An undescribed diaptomid copepod probably belonging to a new Mastigodiaptomus species has been discovered and was very abundant in El Junco Lake (San Cristóbal Island, Ecuador) from 1966 until 2004. The species was not found in samples from 2007, 2008 or 2018. The loss of this key species from the lake coincides with the illegal introduction of Nile tilapia to El Junco Lake in 2005 and its subsequent eradication in 2008. The disappearance of this biogeographically and ecologically important copepod population may be explained by direct mechanisms of predation and competition, by a combination of both processes, and by indirect mechanisms linked to alterations in the lake ecosystem. The effe…
Electrochemical reduction and carboxylation of halobenzophenones
2002
Abstract The electrochemical reduction of a series of halogenated benzophenones XC6H4COC6H4Y (1) was studied in aprotic solvents, in the absence and presence of CO2, by cyclic voltammetry (CV) and controlled-potential electrolysis. The mechanism of electroreduction in dimethylformamide (DMF) has been investigated in some detail. Most of the compounds undergo reductive carbonhalogen bond cleavage in the time window of CV. The radical anions derived from difluorobenzophenones (X=Y=4-F; X=2-F, Y=4-F) as well as from the 3-chloro derivative are quite stable with a cleavage rate constant (kc) of the order of 10−2 s−1 or less. With 4-chloro-, 2-chloro-, 4,4′-dichloro- and 2,4′-dichorobenzophen…
A combined experimental and theoretical study of the thermal [3+2] cycloaddition of carbonyl ylides with activated alkenes
2018
International audience; 4-Benzoyl-3,5-diaryltetrahydrofuran-2,2-dicarbonitriles were first synthesized from 2,2-dicyano-3-aryloxiranes and chalcones at toluene reflux; the 4,5-cis products proved to be predominantly formed and were isolated. Whereas shortened reaction times were observed by using microwave irradiation or catalytic cuprous chloride, no significant stereoselectivity change was in general noticed. Reacting 2,2-dicyano-3-aryloxiranes with 2-cyclopentenone next afforded 3-aryl-4-oxohexahydro-1H-cyclopenta[c]furan-1,1-dicarbonitriles, and the endo stereoisomers were isolated. That no stereoselectivity change was noticed in the presence of cuprous chloride rather suggests an impac…
Chemical Composition and Antimicrobial Activity of the Essential Oil from Flowers of Eryngium triquetrum (Apiaceae) Collected Wild in Sicily
2016
The chemical composition of the essential oil from flowers of Eringium triquetrum Vahl. collected in Sicily was evaluated by GC and GC-MS. The main components were pulegone (50.6%), piperitenone (30.5%) and menthone (7.0%). Comparison of this oil with other studied oils of Eringium species is discussed. The oil showed good antibacterial and antifungal activities against some microorganisms that infest historical art works.
Il mostro argivo (Aesch. Ag. 824)
2014
Il contributo analizza il passo dell'Agamennone di Eschilo (821-829) in cui l'assalto finale a Troia viene presentato dal duce vincitore con un lessico che rinvia a un bestiario mostruoso e crudivoro, in una visione ferina della conquista di Troia, anticipata anche nella parodo dal paragone con gli avvoltoi che si vendicano del nido vuoto. Sotto il filtro mitico della guerra di Troia si cela pertanto una riflessione di tipo etico che individua nella guerra una situazione di limite pericoloso, in cui un essere umano rischia la deriva verso la ferocia e la bestiliatà.
Target analysis and retrospective screening of veterinary drugs, ergot alkaloids, plant toxins and other undesirable substances in feed using liquid …
2015
A comprehensive strategy combining a quantitative method for 77 banned veterinary drugs, mycotoxins, ergot alkaloids and plant toxins, and a post-target screening for 425 substances including pesticides and environmental contaminants in feed were developed using a QuEChERS-based extraction and an ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS). The quantitative method was validated after previous statistical optimisation of the main parameters governing ionisation, and presented recoveries ranging, in general, from 80 to 120%, with a precision in terms of Relative Standard Deviation (RSD) lower than 20%. The full-scan accurate mass data…