Abstract The novel synthesis of 4, 5-dihydro-1, 2, 4-triazin-6-(1H) ones, 2, from 2- isocyanoacetates is described. This synthetic method allows the first synthesis of the unsubstituted parent ring sytem and, in general, gives 2 substituted in only the five position. The assignment of tautomeric structures (2 or 3) to the triazinone products was resolved by spectroscopic means.
