Controllable Fluorocarbon Chain Elongation: TMSCF 2 Br-Enabled Trifluorovinylation and Pentafluorocyclopropylation of Aldehydes.

Controllable fluorocarbon chain elongation (CFCE) is a promising yet underdeveloped strategy for the well-defined synthesis of structurally novel polyfluorinated compounds. Herein, the direct and efficient trifluorovinylation and pentafluorocyclopropylation of aldehydes are described by using TMSCF 2 Br (TMS = trimethylsilyl) as the sole fluorocarbon source, accomplishing the goals of CFCE from C 1 to C 2 and from C 1 to C 3 , respectively. The key to the success of these CFCE processes lies in the unique and diversified chemical reactivity of TMSCF 2 Br, which can serve as two different precursors, namely, a TMSCF 2 radical precursor and a difluorocarbene precursor. Various functional groups are amenable to this new synthetic protocol, providing streamlined access to a broad range of alcohols containing trifluorovinyl or pentafluorocyclopropyl moieties from abundantly available aldehydes. The potential utility of these methods is further demonstrated by the gram-scale synthesis, derivatization, and measurement of log P values of the products.