Electrooxidative Ruthenium-Catalyzed C−H/O−H Annulation by Weak O-Coordination

Electrocatalysis has been identified as a powerful strategy for organometallic catalysis, and yet electrocatalytic C−H activation is restricted to strongly N-coordinating directing groups. The first example of electrocatalytic C−H activation by weak O-coordination is presented, in which a versatile ruthenium(II) carboxylate catalyst enables electrooxidative C−H/O−H functionalization for alkyne annulations in the absence of metal oxidants; thereby exploiting sustainable electricity as the sole oxidant. Mechanistic insights provide strong support for a facile organometallic C−H ruthenation and an effective electrochemical reoxidation of the key ruthenium(0) intermediate.