Regioselective C-H Sulfanylation of Aryl Sulfoxides by Means of Pummerer-Type Activation.

A regioselective C-H sulfanylation of aryl sulfoxides with alkyl aryl sulfides in the presence of acid anhydride was developed, which resulted in the formation of 1,4-disulfanylarenes after dealkylation of initially formed sulfonium salts. The reaction began with Pummerer-type activation of aryl sulfoxides followed by nucleophilic attack of alkyl aryl sulfides. The nucleophilic attack occurred exclusively at the para positions, or at specific positions in case the para position was not available, under perfect control by the dominating sulfoxide directors regardless of any other substituents. The initially formed aryl sulfonium salts were isolable and usefully served as aryl halide surrogates for palladium-catalyzed arylation with sodium tetraarylborates.