Poly(4-vinylpyridinium)hydrogen sulfate: An efficient and recyclable Bronsted acid catalyst for the synthesis of fused 3,4-dihydropyrimidin-2(1H)-ones and thiones

Fused ring 3,4-dihydropyrimidin-2(1H)-ones and thiones were synthesized by the one-pot three component condensation of 6-methoxy-1-tetralone, aromatic aldehydes and urea or thiourea under solvent-free conditions at 120 degrees C utilizing poly(4-vinylpyridinium)hydrogen sulfate as Bronsted acid catalyst. This methodology has an advantage of good yields, shorter reaction times, straight forward workup and reusability of the catalyst over five additional times without losing its activity and product yield. (C) 2012 Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).