Regioselective Reaction of Heterocyclic N‑Oxides, an Acyl Chloride, and Cyclic Thioethers

Treatment of electron deficient pyridine N-oxides with 4-nitrobenzoyl chloride and a cyclic thioether in the presence of triethylamine leads to the corresponding 2-functionalized product in up to a 74% isolated yield. The transformation can also be accomplished with alternative nitrogen containing heterocycles, including quinolines, pyrimidines, and pyrazines. To expand the scope of the transformation, diisopropyl ether can be used as the reaction medium to allow for the use of solid thioether substrates.