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 C? H bond activations with excellent chemo‐, site‐, and diastereoselectivities. The double C? H 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 C? H bond activation by the formation of six‐membered ruthenacycles as the key intermediates.