Mono- and Difluoromethylation\nof 3(2<i>H</i>)‑Pyridazinones

A method for direct <i>N</i>-monofluoromethylation\nof\npyridazinones with <i>S</i>-monofluoromethyl-<i>S</i>-phenyl-2,3,4,5-tetramethylphenylsulfonium triflate is disclosed.\nA method for the <i>N</i>- and <i>O</i>-difluoromethylated\npyridazinones with TMSCF<sub>2</sub>Br as the only promising difluorocarbene\nprecursor is also reported. Substrates with various relevant functional\ngroups, including analogues of Lynparza, are tolerated under both\nmethods.