Ruthenium(II) complexes catalyze the insertion of sulfur dioxide into (het)aryl and alkenyl boronic acids. The transmetalation−sulfination process proceeds with DABSO in the presence of 5 mol % RuCl2(PPh3)3 in methanol at 100 °C. The intermediate sulfinate salt can be quenched with various electrophiles such as alkyl halides, epoxides, Michael acceptors, and λ3-iodanes in moderate to good yields. The reported sulfone synthesis can be performed either as a direct one-pot or one-pot twostep procedure depending on the reactivity of the electrophile.