Nickel-Catalyzed Sulfonylation of Aryl Bromides Enabled by Potassium Metabisulfite as a Uniquely Effective SO 2 Surrogate.

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 (K S O ) as a uniquely effective SO 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 SO insertion occurs via dissolved SO , likely released upon thermal decomposition of K S O . Key to the success of the reaction is the role of K S O as a reservoir of SO that is slowly released, thus preventing catalyst poisoning.