An Efficient Synthesis of Novel Coumarinyldihydropyrimidin-2-thiones Via Coumarinylenones

The novel coumarinyldihydropyrimidin-2-thiones (coumarinyl-DHPM) have been synthesized by Knoevenagel condensation of 4-formylcoumarins with different beta-keto esters in the presence of aluminum chloride (AlCl3) as Lewis acid catalyst leading to coumarinylenones followed by cyclization with protected thiourea and subsequent deprotection of protected sulfur intermediate by trifluoroacetic acid. The structures of coumarinylenones, protected intermediate and the desired coumarinyl-DHPM were confirmed by their NMR and X-ray diffraction analysis. [GRAPHICS]