Reagent Control Enables Selective and Regiodivergent Opening of Unsymmetrical Phenonium Ions.

We report the first examples of selective and regiodivergent opening of unsymmetrical phenonium ions with chloride ions. These reactions are enabled by the dual role of SnCl4 and TiCl4 as Lewis acids and chloride nucleophiles. Reagent control dictates addition of chloride at either the substituted internal position (SnCl4) or unsubstituted terminal position (TiCl4) of the phenonium ion. These reactions are highly selective, stereospecific, operationally simple, and proceed in good to excellent yields. Diverse product utility is demonstrated.