Photo-Induced Ruthenium-Catalyzed Double Remote C(sp2)−H / C(sp3)−H Functionalizations by Radical Relay

Abstract

Distal C(sp2)−H and C(sp3)−H functionalizations have recently emerged as step-economical tools for molecular synthesis. However, while the C(sp2)−C(sp3) construction is of fundamental importance, its formation through double remote C(sp2)−H/C(sp3)−H activation has proven elusive. By merging the ruthenium-catalyzed meta-C(sp2)−H functionalization with an aliphatic hydrogen atom transfer (HAT) process, we, herein, describe the catalyzed twofold remote C(sp2)−H/C(sp3)−H functionalizations via photo-induced ruthenium-mediated radical relay. Thus, meta-C(sp2)−H arene bonds and remote C(sp3)−H alkane bonds were activated by a single catalyst in a single operation. This process was accomplished at room temperature by visible light—notably without exogenous photocatalysts. Experimental and computational theory studies uncovered a manifold comprising ortho-C−H activation, single-electron-transfer (SET), 1,n-HAT (n=5–7) and σ-activation by means of a single ruthenium(II) catalyst.