Polyvinylsulfonic Acid: An Efficient, Water-Soluble and Reusable Bronsted Acid Catalyst for the Three-Component Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones/thiones in Water and Ethanol

A facile and environmentally benign protocol has been developed for the one-pot three-component synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones from the cyclocondensation reaction of aldehyde, ethyl acetoacetate (beta-dicarbonyl compound) and urea or thiourea using polyvinylsulfonic acid as a reusable homogeneous Bronsted acid- and metal-free organocatalyst in water and ethanol. This new protocol has the advantages of easy availability, stability, reusability and eco-friendly of the catalyst, high to excellent yields, simple experimental and work-up procedure.