Molybdooxaziridine-Molybdodioxirane Tandem Catalysis: Synthesis of α-Nitrosulfones from Styrenes

α-Nitrosulfones are valuable molecular scaffolds. This effort reports the MoO₂Dipic promoted α-nitrosulfonation of styrenes using N-Ts-hydroxylamine and H₂O₂. This process starts with the formation of metallooxaziridine 1a that promotes the formation of oxime sulfone 5, which then undergoes molybdodioxirane-promoted oxidation to α-nitrosulfone 3. The reaction works with high yields and stereoselectivites for styrenes with a wide variety of substitution patterns. An atom transfer-radical addition mechanism involving the formation of a Ts radical, difunctionalization, nitroso-oxime isomerization, and final oxidation has been proposed. Initial kinetic and mechanistic data indicates a tandem catalytic process and provides evidence for the proposed mechanism.