Tandem Knoevenagel-Michael reaction with oxidative cyclization in the synthesis of spiro[furo[3,2-<em>c</em>]pyran-2,5′ -pyrimidine] scaffold

The new multicomponent one-pot tandem Knoevenagel-Michael reaction between aromatic aldehydes, <em>N</em>,<em>N'</em>-dimethylbarbituric acid, and 4-hydroxy-6-methyl-2<em>H</em>-pyran-2-one proceeds in alcohols at ambient temperature to selectively afford new substituted unsymmetrical spiro-[furo[3,2-<em>c</em>]pyran-2,5<em>'</em>-pyrimidine] derivatives with two different heterocyclic rings. The procedure involves available non-expensive reactants, mild and convenient conditions, does not require chromatographic isolation and provides excellent yields. The compounds thus obtained are promising for different biomedical applications.