Topic
Benzopyran
About: Benzopyran is a research topic. Over the lifetime, 1889 publications have been published within this topic receiving 15235 citations.
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TL;DR: Spectroscopic (NMR) evidence is presented for the existence of citrinin predominantly in the form of its hemi-acetal in aqueous solutions, suggesting that it is this benzo[c]pyran derivative which interacts with the enzyme, rather than the quinone methide form.
Abstract: The fungal metabolites, citrinin (4,6-dihydro-8-hydroxy-3,4,5-trimethyl-6-oxo-3H-2-benzopyran-7-carboxylic acid) and DHMI (3,4-dihydro-6-methoxy-3,7-dimethyl-lH-2-benzopyran-8-ol), as well as certain synthetic derivatives, have been evaluated for aldose reductase inhibitory activity using a rat lens enzyme preparation. Citrinin and its reduction product, dihydrocitrinin, were found to have significant activity (IC50 < 10 μM), whereas the other compounds were 3-10 times less potent. Kinetic studies showed that citrinin was not an irreversible inhibitor of the enzyme, as might be expected of a quinone methide. Spectroscopic (NMR) evidence is presented for the existence of citrinin predominantly in the form of its hemi-acetal in aqueous solutions, suggesting that it is this benzo[c]pyran derivative which interacts with the enzyme, rather than the quinone methide form.
29 citations
29 citations
TL;DR: In the presence of a radical initiator, azoisobutyronitrile (AIBN) was induced to follow mainly the radical pathway to give the products as mentioned in this paper.
Abstract: 3-(4-Aryloxybut-2-ynyloxy)[1]benzopyran-2-one (1) in refluxing chlorobenzene gave exclusively 1-aryloxymethylpyrano[2,3-c][1]benzopyran-5(3H)-one (6) by a pericyclic path. Compound (1) when heated in nonpolar solvents or in the presence of acid or base, gave exclusively 1-aryloxymethyl-2-methylfuro[2,3-c][1]benzopyran-4-one (10). Additionally this reaction has been studied in the presence of a radical initiator, viz., azoisobutyronitrile (AIBN), and induced to follow mainly the radical pathway to give the products (10). All the butynes (1) studied so far underwent sigmatropic rearrangements at the 4-coumarin-3-yloxypropynyl function of compound (1) to give product(s)(6) and/or (10).
29 citations
TL;DR: Novel chloromethylated and hydroxymethylated 2-oxo-2H-benzo[h]benzopyran derivatives bearing a methoxy substituent were designed and used in the synthesis of a series of fluorescent bioconjugates by linking through an ester or urethane bond to several model neurotransmitter amino acids.
Abstract: Aiming at the development of new benzopyran-based photocleavable protecting groups, novel chloromethylated and hydroxymethylated 2-oxo-2H-benzo[h]benzopyran derivatives bearing a methoxy substituent were designed and used in the synthesis of a series of fluorescent bioconjugates, by linking through an ester or urethane bond to several model neurotransmitter amino acids (glycine, alanine, β-alanine and γ-aminobutyric acid, GABA). The resulting fluorescent bioconjugates with emission in the visible range and high fluorescent quantum yields, were subjected to photocleavage reaction in methanol/HEPES buffer (80:20) solution at different wavelengths of irradiation (250, 300, 350 and 419 nm) and photocleavage kinetic data were obtained.
29 citations
TL;DR: In this paper, it was shown that refluxing in chlorobenzene, ethyl benzene, or xylene, gave exclusively 1-(p-tolyloxymethyl)pyrano[2,3-c][1]benzopyran-5(3H)-one (2), whereas through an ionic or radical pathway 2-methyl-1-to-loxyloxybut-2-ynyloxy(2, 3-c)furo[2.5]-pyrone-4-one (3
Abstract: 3-(4-p-Tolyloxybut-2-ynyloxy)[1]benzopyran-2-one (1), when refluxed in chlorobenzene, ethyl benzene, or xylene, gave exclusively 1-(p-tolyloxymethyl)pyrano[2,3-c][1]benzopyran-5(3H)-one (2), whereas through an ionic or radical pathway 2-methyl-1-(p-tolyloxymethyl)furo[2,3-c][1]benzopyran-4-one (3) was the exclusive product.
28 citations