NMR spectroscopic characterization of keto–enol equilibria of 1, 3-dimethyl-5-((4, 4-dimethyl-2,6-dioxocyclohexyl)(aryl)methyl)pyrimidine-2,4,6(1H,3H,5H)-trione in solution phase

The 1:1 adducts of dimedone with 1, 3-dimethylbenzylidene barbituric gives pyrimidine derivatives that have quite different tautomeric structure in different solution. 1,3-dimethyl-5-((4,4-dimethyl-2,6-dioxocyclohexyl)(phenyl)methyl) pyrimidine-2,4,6(1H,3H,5H)-trione exists as keto-form in polar media like DMSO, while in low polar media like chloroform presents as dienol form.