Water extract of onion catalyzed Knoevenagel condensation reaction: an efficient green procedure for synthesis of α-cyanoacrylonitriles and α-cyanoacrylates

A useful method for Knoevenagel condensation has been developed from the reaction between active methylene compound 1 and aldehyde 2 using the water extract of onion as a green catalyst. This method is suitable for variety of aldehydes including, substituted aromatic, aliphatic, α, β-unsaturated, and heterocyclic with malononitrile or ethyl cyanoacetate, and affords the α-cyanoacrylonitriles and α-cyanoacrylates in excellent yields (Up to 98%). The products are isolated without column chromatography. The use of water extract of onion has several advantages such as low price, easy handling, simple work up procedure and environmentally benign.