ortho-Perfluoroalkylation and Ethoxycarbonyldifluoromethylation of Aromatic Triazenes

A robust protocol for perfluoroalkylation and ethoxycarbonyldifluoromethylation of functionalized aromatic triazenes is described. Using silver(I)-fluoride and different fluorinated (trimethyl)-silyl substituted species, it was possible to synthesize various ortho-fluorinated triazenes in good yields via simple CH-substitution. Initial reactions under solvent-free (neat) conditions indicate a stabilizing interaction between AgRf and the triazene moiety, which may be responsible for the good yields and regioselectivity. The transformation possibilities of the triazene moiety make these reactions interesting for the synthesis of fluorinated building blocks. In addition, quantum chemical calculations suggest that the stabilization of the radical intermediate in the ortho-position is distinctly more favored for aromatic triazenes than for other aromatic substrates.