Results 141 to 150 of about 39,305 (203)
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Highly functionalized 2-amino-4H-pyrans as potent cholinesterase inhibitors
Bioorganic Chemistry, 2018Novel highly functionalized 2-amino-4H-pyrans were achieved in excellent yields under simple grinding at ambient temperature and were assessed for their potential for treating Alzheimer's disease (AD). The 2-amino-4H-pyran bearing nitro groups on both the aryl rings showed the highest activity, with an IC50 of 1.98 ± 0.09 µM against ...
Raju Suresh Kumar +2 more
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Cerium(III) Chloride–Catalyzed One-Pot Synthesis of Tetrahydrobenzo[b]pyrans
Synthetic Communications, 2009 Efficient one-pot synthesis of 4H-benzo[b]pyrans via a three-component cyclocondensation of aryl aldehydes, malononitrile, and dimedone has been reported using CeCl3·7H2O as ...
Gowravaram Sabitha, B S Sastry
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Chemistry of Heterocyclic Compounds, 1983
Data on the chemistry of monocyclic, unsaturated, six-membered, oxygen-containing heterocycles, viz., 4H-pyrans, are correlated and systematized for the first time. The methods for their synthesis, their transformations, and spectroscopic data for them are discussed. The interest in these compounds, which has increased recently, is due to the fact that
O. V. Drygina, A. D. Garnovskii
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Data on the chemistry of monocyclic, unsaturated, six-membered, oxygen-containing heterocycles, viz., 4H-pyrans, are correlated and systematized for the first time. The methods for their synthesis, their transformations, and spectroscopic data for them are discussed. The interest in these compounds, which has increased recently, is due to the fact that
O. V. Drygina, A. D. Garnovskii
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Synthesis of Novel Hybrid 4H-Pyran-lipoic and 4H-Pyran-azetidine Derivatives
Synthesis, 2017In this study, a molecular hybridization strategy was used to design and synthesize two novel series of hybrid compounds: 4H-pyran-lipoic and 4H-pyran-azetidine, employing ammonium hydroxide and involving the participation of aldehydes, malononitrile, and compounds derived from β-ketoesters to obtain the products with good yields.
Miguel Vázquez +7 more
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Structure of 2,4,4,6-tetraphenyl-4H-pyran
Acta Crystallographica Section C Crystal Structure Communications, 1990C 29 H 22 O cristallise dans P2 1 /c avec a=12,128, b=12,372, c=14,599A, β=105,57°, Z=4 ; affinement jusqu'a R=0,039. Le cycle 4H-pyrane est rigoureusement plan avec les cycles phenyl substitues sur les atomes C(sp 2 ) de C2 et C6. Le cycle presente une conformation bateau legerement tordue avec les angles bateau de 4,3 et 7,7° sur C(sp 2 ) et O ...
J. Vojtěchovský, J. Hašek
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Cyclopropanation of areno-condensed 4H-pyrans with dihalocarbenes
Chemistry of Heterocyclic Compounds, 2020The addition of dihalocarbenes to 1H-benzo[f]chromenes and 4H-chromenes gave a number of dihalotetrahydro(benzo)cyclopropa[b]-chromenes containing donor and acceptor substituents at different positions. It was found that in the case of 1,3-disubstituted 1H-benzo[f]-chromenes, the reaction proceeds diastereoselectively with the formation of trans ...
Irina А. Semenova +4 more
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ChemInform Abstract: RING TRANSFORMATIONS OF 4H‐PYRANS. PYRIDINES FROM 2‐AMINO‐4H‐PYRANS
Chemischer Informationsdienst, 1981AbstractAus den 2‐Amino‐4H‐pyranen (I) erhält man mit Nitrosylschwefelsäure und Essigsäure die entsprechend substituierten Pyridone (II).
C. SEOANE +3 more
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Collection of Czechoslovak Chemical Communications, 1987
Base-catalyzed addition of β-dicarbonyl compounds to methylenemalonaldehydes led to tetracarbonyl compounds II which were dehydrated in an acid medium to 4H-pyran-5-carboxaldehydes III. In the addition of compounds containing a nitrile group, the primarily formed addition products were immediately cyclized to give directly 2-amino-4H-pyran-5 ...
Dalimil Dvořák +4 more
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Base-catalyzed addition of β-dicarbonyl compounds to methylenemalonaldehydes led to tetracarbonyl compounds II which were dehydrated in an acid medium to 4H-pyran-5-carboxaldehydes III. In the addition of compounds containing a nitrile group, the primarily formed addition products were immediately cyclized to give directly 2-amino-4H-pyran-5 ...
Dalimil Dvořák +4 more
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Synthesis and properties of 3-formyl-4H-pyrans
Chemistry of Heterocyclic Compounds, 1990The Vilsmeier formylation of 4H-pyrans afforded 3-formyl-4H-pyrans. These were converted to 3-formylpyrylium salts, from which pyridine or pyridine salts with an aldehyde group at C(3) were obtained. The reaction between 3-formyl-4-allyl-4H-pyran and methyltrifluoromethanesulfonate proceeded via a Koop rearrangement.
K. F. Suzdalev, A. V. Koblik
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2,4,6-Triphenyl-4H-pyran-3,5-dicarboxaldehyde
Acta Crystallographica Section C Crystal Structure Communications, 1996The structure of 2,4,6-triphenyl-4H-pyran-3,5-dicarboxaldehyde, C25H18O3, a potential fungicide, has a pyran ring in a flattened boat conformation, but with C4 and O3 displaced from the basal plane by 0.299 and 0.159 A, respectively. The aldehyde groups display an ap orientation with respect to the double bonds of that plane.
S. Selladurai +5 more
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