A new entry to the synthesis of 5-substituted 1,2,3-triazines by reaction with silyl enol ethers and ceric ammonium nitrate

Monocyclic 1,2,3-triazines have been allowed to react with silyl enol ether or ketene silyl acetal in the presence of 1-chloroethyl chloroformate to give 2-(1-chloroethoxycarbonyl)-5-substituted-2,5-dihydrotriazines in good yields. These dihydro adducts are oxidized by ceric ammonium nitrate in CH3CN–H2O to afford 5-substituted 1,2,3-triazines.