Facile Knoevenagel and Domino Knoevenagel/Michael Reactions Using Gel-Entrapped Base Catalysts

An efficient method for Knoevenagel condensation of arenecarbaldehydes with active methylene compounds such as barbituric acid and Meldrum's acid in the presence of gel-entrapped base catalysts is reported. The method has been extended to the one-pot synthesis of arylmethylene-bis[3-hydroxycyclohex-2-en-1-one] derivatives from dimedone (=5,5-dimethylcyclohexane-1,3-dione) and arenecarbaldehydes by using domino Knoevenagel/Michael reaction sequence.