An efficient one-pot synthesis of functionalized 2-amino-4H-pyrans by a meglumine-catalyzed three-component reaction has been developed. A broad range of substrates including aromatic and heteroaromatic aldehydes, isatin derivatives, and acenaphthenequinone are condensed with enolizable C-H activated compounds and alkylmalonates to give the desired products in high to excellent yields. This met...

In the title mol-ecule, C(19)H(20)N(2)O(2), the cyclo-hexene ring adopts a sofa conformation, while the pyran ring adopts a flattened boat conformation. In the crystal, mol-ecules are linked by N-H⋯N and N-H⋯O hydrogen bonds, forming a two-dimensional network parallel to (010).

A DABCO-catalyzed (3 + 3) annulation between 2-(acetoxymethyl)buta-2,3-dienoate and sulfur ylides has been developed, which provides a facile method for the synthesis of 4H-pyrans bearing a vinyl sulfide group.

A facile and efficient one-pot synthesis of substituted cyclophosphamidic chlorides and their analogues has been developed from readily available enaminones, 2-arylamino-3-acetyl-5,6-dihydro-4H-pyrans.

Highly substituted 4H-pyrans can be smoothly synthesized from readily available 2-(1-alkynyl)-2-alkene-1-ones by DBU- or n-Bu(3)P catalyzed hetero-[4+2] cycloaddition reactions, in which 2-(1-alkynyl)-2-alkene-1-ones act as both heterodiene and heterodinenophile.

triphenyl phosphine(pph3), an efficient and reusable catalyst, catalysed the synthesis of 2-amino-3-cyano-6-methyl-4-aryl-4h-pyran-5-ethylcarboxylate derivatives by one-pot condensation of aromatic aldehydes, malononitrile and ethyl acetoacetate in etoh-h2o (1:1) at reflux conditions. the results show that aromatic aldehydes containing electron-donating groups or electron-withdrawing groups cou...

A facile, convenient, green and environmentally benign one-pot three-component synthesis of poly-functionalized 4H-pyrans and 4H-chromenes is described. A basic ionic liquid 2-(2-hydroxyethoxy)ethaneammonium formate was found to be an efficient catalyst or catalytically active solvent for the synthesis of those important classes of heterocyclic compounds.

A variety of substituted 4H-pyrans are readily prepared in moderate to good yields under the mild reaction conditions by nucleophilic addition to electron-deficient 1,3-conjugated enynes with phase-transfer catalysis (PTC).