Exclusive Aromatic vs Aliphatic C-H Bond Functionalization by Carbene Insertion with Gold-Based Catalysts

The direct functionalization of aromatic C-H bonds by carbene insertion from diazo compounds catalyzed by gold complexes with N-heterocyclic ligands is described. The reaction is completely selective toward the C(sp2)-H bonds, other C(sp3)-H bonds remaining unreacted. A study with several NHC ligands in Au(I) and Au(III) complexes has been performed. The potential application of this strategy to give profen derivatives has also been explored.