Three-Component Heterocyclization of <i>gem</i>-Bromofluorocyclopropanes with NOBF₄: Access to 4‑Fluoropyrimidine <i>N</i>‑Oxides

Novel three-component heterocyclization involving gem-bromofluorocyclopropanes, nitrosyl tetrafluoroborate, and a molecule of the solvent (nitrile) yielding previously unknown fluorinated pyrimidine N-oxides is described. A two-step synthetic approach to 4-fluoropyrimidine N-oxides from alkenes under mild conditions is developed using this reaction. Mechanistic aspects of the heterocyclization are discussed.