Results 171 to 180 of about 15,469 (227)
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Synthesis of pyrone carbaldehydes, pyrone sulfonium ylides and related epoxides
Journal of Heterocyclic Chemistry, 2009Abstract 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, 1968Preliminary 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, 1993Abstract 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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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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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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Synthesis of substituted ?-pyrones
Chemistry of Heterocyclic Compounds, 1972Substituted 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 +2 more
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ChemInform Abstract: SYNTHESIS OF 5,6‐DIHYDRO‐2‐PYRONE AND 2‐PYRONE
Chemischer Informationsdienst, 1974AbstractVinylessigsäure (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 +4 more
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Preparation of the Geranyl-α-pyrone (±)-Aurantiacone via a New Pyrone Synthesis
Synlett, 2007The 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 +4 more
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Photocycloadditions to a pyrone analogue
Journal of Photochemistry and Photobiology A: Chemistry, 1991Abstract 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 +3 more
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Tetrahedron, 1967
Abstract Further studies on the use of pyrones for the biogenetic-type synthesis of phenolic compounds are reported. In particular some control over the direction of cyclization of the intermediate β-triketo ester chain is demonstrated. This control makes possible the synthesis of two basic types of phenolic compound from the same precursor and is ...
T. Money +4 more
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Abstract Further studies on the use of pyrones for the biogenetic-type synthesis of phenolic compounds are reported. In particular some control over the direction of cyclization of the intermediate β-triketo ester chain is demonstrated. This control makes possible the synthesis of two basic types of phenolic compound from the same precursor and is ...
T. Money +4 more
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2011
Since 1893, acetate has been regarded as a very important precursor of naturally occurring phenolic compounds. Although intensive work has been directed at the complete elucidation of this biogenetic pathway, a satisfactory method has yet to be devised for the synthesis of the polyketide chains proposed as intermediates in the acetate scheme. Labelling
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Since 1893, acetate has been regarded as a very important precursor of naturally occurring phenolic compounds. Although intensive work has been directed at the complete elucidation of this biogenetic pathway, a satisfactory method has yet to be devised for the synthesis of the polyketide chains proposed as intermediates in the acetate scheme. Labelling
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