4-Aryl-6-methyl-3, 4-dihydropyrimidin-2 (1H)-one (DHPM) scaffolds of Biginelli type were oxidized using Co (II)/S2O82− and the reaction afforded 6-unsubstituted pyrimidin-2 (1H)- ones through an unprecedented dealkylation process. 4-Alkyl DHPMs under similar conditions afforded yet another unusual product, ethyl tetrahydropyrimidin-2, 4 (1H, 3H)- dione-5-carboxylate.