Results 121 to 130 of about 90,377 (200)

Synthetic Strategies Toward 2H‐, 4H‐Pyrans, and Pyranones: Recent Advances

ChemistrySelect
Pyrans are a class of six‐membered heterocyclic rings containing five carbon atoms and one oxygen atom. They are non‐aromatic in nature, bearing two double bonds in the ring.
S. Samai, Sanghamitra Atta, M. Singh
semanticscholar   +1 more source

Three-Component Efficient Synthesis of 2-Amino-3-cyano-4H-pyrans Catalyzed by Diammonium hydrogen phosphate in Aqueous Media

, 2020
The present method is facile, green and effective for the synthesis of 2-amino-3-cyano-4H-pyran derivatives which are obtained by one-pot three-component condensation reactions of aromatic aldehydes, malononitrile and methyl acetoacetate using ...
Pardis Hafez Taghva, H. Kabirifard
semanticscholar   +1 more source

Michael reaction of methylenemalonaldehydes: Synthetic approach to 4H-pyran-5-carboxaldehydes and 2-amino-4H-pyran-5-carboxaldehydes

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, David Šaman, Jana Hodačová, Vladimír Král, Zdeněk Arnold   +4 more
openaire   +1 more source

Difluorocarbene-Enabled Trifluoromethylation and Cyclization for the Synthesis of 3-(Trifluoromethyl)-4H-pyrans.

Organic Letters
A three-component annulation reaction and trifluoromethylation for the construction of 3-(trifluoromethyl)-4H-pyrans using β-CF3-1,3-enynes, BrCF2CO2Et, and sulfoxonium ylides as readily available substrates has been developed.
Chun‐Yan Wu, Xiang-Long Chen, Dong-Sheng Yang, Yong-xing Tang, Li-Sheng Wang, Yong-Dong Du, Yan‐Dong Wu, An‐Xin Wu   +7 more
semanticscholar   +1 more source

2,4,6-Triphenyl-4H-pyran-3,5-dicarboxaldehyde

Acta Crystallographica Section C Crystal Structure Communications, 1996
The 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, R. Murugesan, K. Subramanian, Y. S. Chen, S. N. Rao, E. M. Holt   +5 more
openaire   +1 more source

Synthesis and properties of 3-formyl-4H-pyrans

Chemistry of Heterocyclic Compounds, 1990
The 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
openaire   +1 more source

Enantioselective Synthesis of Multifunctionalized 4H-Pyrans via Formal [4 + 2] Annulation Process by Bifunctional Phosphonium Salt Catalysis.

Organic Letters, 2019
A highly enantioselective formal [4 + 2] annulation involving electron-deficient allenes as C2-synthons has been developed under bifunctional phosphonium salt catalysis.
Jia-Hong Wu, Jianke Pan, J. Du, Xiao-xiang Wang, Xuemei Wang, Chunhui Jiang, Tianli Wang   +6 more
semanticscholar   +1 more source

4-Phenyl-4H-pyrans as IKCa channel blockers

Bioorganic & Medicinal Chemistry Letters, 2003
AbstractFor Abstract see ChemInform Abstract in Full Text.
Klaus, Urbahns, Ervin, Horváth, Johannes Peter, Stasch, Frank, Mauler   +3 more
openaire   +2 more sources

Efficient and Convenient Method for the Synthesis of Poly Functionalised 4H‐Pyrans

Synthetic Communications, 2004
AbstractFor Abstract see ChemInform Abstract in Full Text.
B. P. V. Lingaiah, G. Venkat Reddy, T. Yakaiah, B. Narsaiah, S. N. Reddy, R. Yadla, P. Shanthan Rao   +6 more
openaire   +1 more source

ChemInform Abstract: METALATION OF DIHYDRO‐4H‐PYRANS DERIVATIVES. PREPARATION OF 2‐ALKYL‐3‐CHLORO‐5,6‐DIHYDRO‐4H‐PYRANS

Chemischer Informationsdienst, 1977
AbstractDas Dihydropyran (Ia) oder sein 3‐Chlorderivat (Ib) werden lithiiert und die entstandenen Verbindungen (II) mit Alkyljodiden zu den Titelverbindungen (III) umgesetzt.
O. RIOBE, A. LEBOUC, J. DELAUNAY
openaire   +1 more source