Substituted bicyclic arenes gave fluorination products 2AC-2AF, however, for some substrates such as 1AC and 1AE, the fluorination reactions were more difficult. After extensive screening of additives, we found that NaClO4 (1.0 equiv) was effective for increasing yields (see the Supporting Information for details). For example, without this additive, 1AC gave 2AC in only 51% yield, but with the additive, the yield improved to 87%. The role of the additive remains unclear, but we hypothesize that the counter anion exchange in the intermediate might affect the acidity of the proton at the C3 position. This fluorination was also applicable to other pyrazoloazines: pyrazolopyrimidine with a phenyl group at the C3 position gave fluorinated compounds 2AG-2AI in high yields. 6-Bromopyrazolopyrimidine with various aryl groups at the C3 position gave fluorinated compounds 2AJ-2AL as well. The ring-opening fluorination proceeded well even when using zaleplon, a hypnotic agent, for which the desired product 2AM was obtained. The reaction was also applicable to pyrazolopyrazine, triazine, quinoline, and quinazoline, giving fluorinated products 2AN-2AQ in moderate yields.