Written by: Dr. Sharbil J. Firsan

A mild, regioselective protocol for the C–H functionalization of heteroarenes has been reported by Lu and Falck.  This method, which is a marked improvement over existing ones for the direct silylation of heteroarenes, employs [{Ir(OMe)(cod)}₂] as catalyst, Et₃SiH as the inexpensive silylating reagent, and 4,4-di-tert-butyl-2,2-bipyridine as ligand.  Some of the attractive features of this process are:

• Moderate-to-high yields and high regioselectivities are observed.
• Only a small excess (3 equiv) of the silylating reagent is needed.
• Protection of the NH group in indoles is not required.
• Electron-donating and electron-withdrawing substituents in the heteroarene are tolerated.
• 2-Norbornene is used as a promoter and is believed to function as a hydrogen sink for the hydrogen produced in the reaction.

(1) Lu, B.; Falck, J. R. Angew. Chem., Int. Ed. 2008, 47, 7508.