Rapid and General Access to α-Haloketones Using Quaternary Ammonium Salts as Halogen Sources.

A general, rapid, and scalable method for the preparation of α-halogenated ketones using N-alkenoxypyridinium salts as substrates and quaternary ammonium salts as halogen sources was developed, featuring mild reaction conditions, excellent functional group tolerance, short reaction times, and a wide substrate scope.