Bifunctional Urea/Hg(OAc)(2)-Mediated Synthesis of 4-Aryl-6(-)oxycarbonyl-2-pyrones and 2-Pyridones from Dithiomalonate and beta,gamma-Unsaturated alpha-Keto Esters

Disubstituted 2-pyrones and 2-pyridones were obtained by bifunctional urea-catalyzed Michael addition/ lactonization or lactamization followed by a Hg(OAc)(2)- or Hg(OAc)(2)/DBU-mediated hydrolysis/decarboxylation/dehydrogenation process. This one-pot two-stage protocol enabled the rapid synthesis of 4,6-disubstituted 2-pyrones and 2-pyridones from dithiomalonate and beta,gamma-unsaturated alpha-keto esters in practical yields under mild reaction conditions. Additionally, the obtained 2-pyridones were facilely transformed to 2,4,6-trisubstituted pyridines in excellent yields.