Melamine trisulfonic acid: A new, efficient and recyclable catalyst for the synthesis of 3,4-dihydro

Melamine trisulfonic acid (MTSA) can be used as an efficient and recyclable catalyst for the promotion of the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones (DHPMs) in the absence of solvent. All reactions were performed at 80 ℃ in good to high yields.