Ultrafast Mechanochemical Epoxidation of Aldehydes and Ketones

Abstract We report a mechanochemical Corey–Chaykovsky epoxidation that converts aldehydes and ketones to epoxides within minutes under an ambient atmosphere using sulfonium or sulfoxonium salts, KOH, and minimal liquid additives. The method accommodates a broad substrate scope, is readily scalable, and often enables simple extraction without chromatography. It further enables telescoped sulfonium generation–oxidation–epoxidation, tunable enone chemoselectivity, and direct conversion of imines to unstabilized aziridines. An unexpected dependence of reactivity on the ylide precursor halide reveals distinct mechanochemical reactivity from that under conventional solution-phase conditions.