Knoevenagel condensation between C-glycoside and active methylene compounds without catalysts

A Knoevenagel condensation reaction between a C-glycoside based aromatic aldehyde and cyclic active methylene compounds such as barbituric acid, thiobarbituric acid, 1,3-dimethylbarbituric acid, 5,5-dimethyl-1,3-cyclohexanedione, 2,2-dimethyl-1,3-dioxane-4,6-dione and 3-methyl-1-phenyl-2-pyrazolin-5-one has been developed, to give a series of unusual fused heterocyclic compounds. The structures of all the new compounds were established by the spectral data. This method which did not use any catalysts, has the advantages of operational simplicity and minimal environmental impact.