Application of β-Oxodithioesters in Domino and Multicomponent Reactions: Facile Route to Dihydropyrimidines and Coumarins

A facile route to hitherto unknown 5-methylmercaptothiocarbonyl-4-aryl-3,4-dihydropyrimidin-2(1H)-ones and substituted 2H-chromene-2-thiones has been developed. SnCl2-catalyzed cyclocondensation of β-oxodithioesters with a variety of readily accessible aldehydes and urea affords the dihydropyrimidinones. The methodology involves the three-component Biginelli reaction. On the other hand, substituted salicylaldehyde and β-oxodithioesters reacted under the same condition to afford the substituted 2H-chromene-2-thiones in high yields.