Synthesis of Sulfonyl, Sulfonimidoyl, and Sulfoxyl Fluorides under Solvent-Free Mechanochemical Conditions in a Mixer Mill by Imidazole-to-Fluorine Exchange

A sustainable, mechanochemical procedure for the synthesis of sulfur(VI) fluorides starting from readily available sulfur(VI) 2-methylimidazoles as stable S(VI) precursors has been developed. The transformation proceeds with potassium bifluoride (KHF2) as the fluorine source in the presence of acetic acid (AcOH) in a mixer mill under solvent-free conditions. The corresponding sulfonyl, sulfonimidoyl, and sulfoxyl fluorides are formed in good to excellent yields. Compared with the solution-based counterpart, the reaction times are shorter. This environmentally benign mechanochemical approach exhibits significant ecological advantages and requires less resources for the optimized purification by simple silica plug filtration. X = O, NTs or NBoc R = aryl, alkyl or LA' KH 2 AcOH ball milling center dot stable S(VI) reservoir center dot solvent-free center dot single step & safe center dot simple purification O, ,X RF 26 examples up to 93% yield