I) with hydrogen peroxide or Oxone gives dihydropyrimidines which are easily further oxidized to pyrimidines (III) with KMnO4. Direct treatment of (I) and the oxo analogues (V) with KMnO4 yields 2-hydroxypyrimidines. -(KIM, S. S.; CHOI, B. S.; LEE, J. H.; LEE, K. K.; LEE, T. H.; KIM, Y. H.; SHIN*, H.; Synlett 2009, 4, 599-602; Chem. Dev. Div., LG Life Sci., Ltd./R&D, Daejeon 305-380, S. Korea; Eng.) -Mais 28-143

We have devised a new route toward 2-unsubstituted pyrimidine derivatives from the Biginelli product, dihydropyrimidin-2(1H)-thiones in two steps: Oxidation of dihydropyrimidin-2(1H)-thiones using oxone on wet alumina or hydrogen peroxide in the presence of catalytic amount of vanadyl sulfate provided 1,4-dihydropyrimidine, which was further oxidized to 2-unsubstituted pyrimidines by the treatment of KMnO 4 . Oxidation of dihydropyrimidin-2(1H)-ones by KMnO 4 formed 2-hydroxypyrimidine in excellent yield, whereas attempted direct desulfurative aromatization of dihydropyrimidin-2(1H)-thiones by KMnO 4 resulted in the formation of 2-hydroxypyrimidines, the same products obtained in the oxidation of dihydropyrimidin-2(1H)-one.