Results 161 to 170 of about 4,197 (216)

Pyrones as bacterial signaling molecules

Nature Chemical Biology, 2013
Bacteria communicate via small diffusible molecules and thereby mediate group-coordinated behavior, a process referred to as quorum sensing. The prototypical quorum sensing system found in Gram-negative bacteria consists of a LuxI-type autoinducer synthase that produces N-acyl homoserine lactones (AHLs) as signals and a LuxR-type receptor that detects ...
Alexander O Brachmann, Sophie Brameyer, Darko Kresovic, Ivana Hitkova, Yannick Kopp, Christian Manske, Karin Schubert, Helge B Bode, Ralf Heermann   +8 more
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Photocycloaddition Reactions of 2-Pyrones

ChemInform, 2003
AbstractFor Abstract see ChemInform Abstract in Full Text.
Tetsuro Shimo, Kenichi Somekawa
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Synthesis of pyrone carbaldehydes, pyrone sulfonium ylides and related epoxides

Journal of Heterocyclic Chemistry, 2009
Abstract magnified imageHexaminium salts of 4‐pyrones 3a, 3b were synthesized by treatment of 2‐(4‐bromomethylphenyl)‐6‐methyl‐4H‐pyran‐4‐one 2a and 2‐(4‐bromomethylphenyl)‐6‐phenyl‐4H‐pyran‐4‐one 2b with hexamethyl‐enetetramine in chloroform in 71 and 84% yields respectively.
Aziz Shahrisa, Mahnaz Saraei
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Pyrone studies. Linear α-pyrone route to protected β-polyketones

Canadian Journal of Chemistry, 1968
Preliminary studies on an alternative polypyrone route to protected β-polyketo acid chains are reported. The synthesis of the basic pyrone units involved and their conversion to C-3 acylated compounds are described.
J. L. Douglas, T. Money
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Alkylative carbonyl transposition of dihydro-α-pyrones to dihydro-α-pyrones

Tetrahedron Letters, 1993
Abstract Dihydro-α-pyrones ( 2 ) are prepared from β-hydroxy ketones ( 1 ). Dihydropyrones ( 2 ) are transformed to unsaturated δ-lactones ( 4 ) via an alkylative 1,3-carbonyl transposition.
A. Nangia, P.Bheema Rao
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On the nitration of 2‐pyrone

Journal of Heterocyclic Chemistry, 1969
AbstractA 1:1 adducl of 2‐pyrone and nitronium fluoroborate has been delected by nmr and is a possible precursor of 5‐nitro‐2‐pyrone, a subsequently formed product. From comparison of the nmr spectra of the 1:1 adduct and 2‐methoxypyrylium fluoroborate, the adduct is believed to be the pyrylium fluoroborate derived from nitration of the carbonyl oxygen
W. H. Pirkle, M. Dines
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Preparation of the Geranyl-α-pyrone (±)-Aurantiacone via a New Pyrone Synthesis

Synlett, 2007
The structure of the leaf resin geranyl-α-pyrone auranti-acone isolated from Mimulus ( = Diplacus) aurantiacus (Curtis) Jeps. (Scrophulariaceae) was confirmed through synthesis. The key step is lactonization of the sensitive 5-hydroxy-3-oxopent-4-enoic acid under mild conditions, which can be released from the corresponding bispotassium salt.
Uwe Beifuss, Dietmar Schmidt, Jürgen Conrad, Iris Klaiber, Sabine Mika   +4 more
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ChemInform Abstract: SYNTHESIS OF 5,6‐DIHYDRO‐2‐PYRONE AND 2‐PYRONE

Chemischer Informationsdienst, 1974
AbstractVinylessigsäure (I) reagiert mit Formaldehyd (II) in siedendem Eisessig ′in Gegenwart von konz. Schwefelsäure in bescheidenen Ausbeuten zum 5;6‐Dihydro‐2‐pyron (III), das nach Bromierung mit n‐Bromsuccinimid (V) in Tetrachlorkohlenstoff zu (VI) und Dehydrobromierung mit Triäthylamin 2‐Pyron (VII) ergibt.
M. NAKAGAWA, M. TONOZUKA, M. OBI, M. KIUCHI, T. HINO   +4 more
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Synthesis of substituted ?-pyrones

Chemistry of Heterocyclic Compounds, 1972
Substituted γ-pyrones were synthesized by the acylation of phenylacetaldehyde and its enol acetate with acetic and propionic anhydrides in the presence of 70% HClO4. The mechanism of the reaction is examined, and the IR and PMR spectra of the synthesized γ-pyrones are presented. Some of their transformations were studied.
E. V. Kuznetsov, A. I. Pyshchev, G. N. Dorofeenko   +2 more
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Photocycloadditions to a pyrone analogue

Journal of Photochemistry and Photobiology A: Chemistry, 1991
Abstract Irradiation of the dicyanomethylenepyran 1 in methanol gave two dimers, 5 and 6. In the presence of ethyl vinyl ether and acrylonitrile, the major photoproducts were 9 and 12 respectively. All these results are explained by initial [2+2] cycloaddition to the exocyclic double bond of 1 to give cyclobutane intermediates, which undergo ring ...
Christopher J. Samuel, Haydn G. Beaton, Kenneth Davey, C.James Reader   +3 more
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