Ruthenium(II)‐Catalyzed CH Alkenylations of Phenols with Removable Directing Groups

Cationic ruthenium(II) complexes enabled oxidative alkenylations of phenols bearing easily cleavable directing groups. The optimized catalytic system allowed twofold CH bond activations with excellent chemo‐, site‐, and diastereoselectivities. The double CH functionalization process proceeded efficiently in an aerobic fashion under an atmosphere of ambient air. Detailed mechanistic studies were performed and provided strong support for an initial reversible CH bond activation by the formation of six‐membered ruthenacycles as the key intermediates.