Nano-Silica phosphoric acid: an efficient catalyst for one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones (thiones) under solvent-free or sonication conditions

Two simple protocols for the synthesis of three-component condensation reaction of an aldehyde, B-ketoester and urea or thiourea to obtain the 3, 4-dihydropyrimidin-2(1H)-ones (thiones) using nano silica phosphoric acid are reported. Short reaction times, high yields, reusability of catalyst and easy workup are some advantages of these protocols.