Synthesis of novel silylated 1,2,4-triazin-5-ones

The reaction of various α-silyl-α-keto esters with thiosemicarbazide at 50 °C in ethyl acetate was found to give α-silyl-substituted thiosemicarbazone-acetic acid esters in good yield. These may then be converted to their corresponding silyl-substituted 1,2,4-triazin-5-ones by cyclization under basic conditions.