The base-promoted cyclization of N-Boc arylimidrazone toward 1,2-dihydro 3H-1,2,4-triazol-3-ones

We reported the base-promoted cyclization of N-Boc arylimidrazone toward 1,2-dihydro 3H-1,2,4-triazol-3-one. This procedure tolerated methyl, methoxy, chloro, bromo, fluoro, cyano, methylcarbonyl groups well. Thus, it represents a facile and high efficient pathway leading to 1,2-dihydro 3H-1,2,4-triazol-3-one. Mechanism study revealed this procedure proceeded with the intramolecular nucleophilic cyclization rather than N-isocyanate intermediate.