Synthesis of N,N-Dioxopyridazines

Despite many efforts, one of the smallest heterocycles containing two nitrogen atoms, pyridazine, could not be converted to its N,N-dioxide (see, however, Nakadate et al. Chem. Pharm. Bull. 1970, 18, 1211–1218). HOF·CH3CN, made easily from diluted fluorine, was able to accomplish this task in a fast reaction with good yields.