Rhodium-Catalyzed Selective C-H Trideuteromethylation of Indole at C7 Position Using Acetic-d6 Anhydride. 
Rhodium-catalyzed C7-selective decarbonylative trideuteromethylation of indoles with commercially available Ac2O-d6 via C-H and C-C bond activation has been developed.  The key to the high reactivity and regioselectivity of this transformation is the appropriate choice of an indole N-PtBu2 chelation-assisting group.  This method has many advantages, including easy access and removal of the directing group, the use of cheap and widely available deuterium methylating source, no requirement of an external ligand or oxidant, a broader substrate scope, high efficiency, and the sole regioisomer.