Synthesis of Vinyl Sulfones from Substituted Alkenes via Molybdooxaziridine Catalysis

Herein we report the MoO₂Dipic promoted sulfonation of alkenes using N−Ts-hydroxylamine as the quantitative source of Ts. The reaction works with high yields and stereoselectivities for styrenes with a wide variety of substitution patterns. A novel atom transfer radical addition mechanism involving the formation of molybdooxaziridine complex 1 as the active catalyst, difunctionalization with Ts-NO, followed by oxidation, and then elimination as the rate-determining-step for the formation of vinylsulfone 3 has been proposed. Initial kinetic and mechanistic data indicates the formation of Ts-NO and provides evidence for the proposed mechanism.