Rate accelerations in trichloroisocyanuric acid and trichlorotriazine promoted synthesis of 3,4-dihydropyrimidinones/thiones under Vilsmeier-Haack and solvent free conditions

In the present study, we have accomplished N,N’-dimethyl formamide (DMF)/trichloroisocyanuric acid and DMF/trichlorotriazine as efficient catalysts for the synthesis of 3,4-dihydropyrimidinones/thiones from one-pot multi-component reaction of β-ketoester, aromatic aldehydes, and urea under reflux condition. The reaction operates also under solvent free microwave condition. The results obtained from this study were compared with those obtained from classical Vilsmeier-Haack adducts (DMF/POCl3 and DMF/SOCl2) as catalysts. Reaction times and product yields observed in this study indicated shorter reaction times and better product yields with modified VH reagents (TCCA/DMF and TCTA/DMF) over classical VH reagents (POCl3/DMF and SOCl2/DMF). The catalytic activity of (TCTA/DMF)>(TCCA/DMF)>(POCl3/DMF>SOCl2/DMF).