The development and mechanistic investigation of a nickel-catalyzed sulfonylation of aryl bromides is disclosed. The reaction proceeds in good yields for a variety of substrates and utilizes an inexpensive, stench-free, inorganic sulfur salt (K2 S2 O5 ) as a uniquely effective SO2 surrogate. The active oxidative addition complex was synthesized, isolated, and fully characterized by a combination of NMR spectroscopy and X-ray crystallography analysis. The use of the isolated oxidative addition complex in both stoichiometric and catalytic reactions revealed that SO2 insertion occurs via dissolved SO2 , likely released upon thermal decomposition of K2 S2 O5 . Key to the success of the reaction is the role of K2 S2 O5 as a reservoir of SO2 that is slowly released, thus preventing catalyst poisoning.
Keywords: Mechanism; Nickel; Reductive Coupling; Sulfonylation.
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