- Preparation and Functionalization of a Range of Main-Group Trifluoropropynyl Organometallic Compounds: The Application of Metalloid-Directed Carbolithiation to the Selective Synthesis of Novel Fluorocarbon Fragments
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The reaction of 1,1,1,3,3-pentafluoropropane (CF3CH 2CF2H, HFC-245fa) with 3 equiv of n-butyllithium at -10 °C leads to the generation of trifluoropropynyllithium in excellent yields. This reagent reacts readily with a range of group 14 electrophiles R 4-n-EXn (R = Ph, Et; E = C, Si, Ge, Sn, Pb; X = Cl, Br) to yield the organometalloid trifluoropropynyl compounds R 4-nE(C≡CCF3)n. Three of these compounds, Ph3EC≡CCF3 (E = C, Si, Ge), have been crystallographically characterized, representing the first such study of these materials. The silane Ph3SiC≡CCF3 has been derivatized by reaction with LiAlH4 and a range of organolithium reagents (RLi, R = n-Bu, Ph, t-Bu) to afford a new series of β-CF 3-substituted vinylsilanes of the type Ph3SiCH=C(CF 3)R, with predominantly E geometry at the double bond. In the cases R = n-Bu, t-Bu, and Ph, these materials have been crystallographically characterized. Additionally, a remarkably facile cyclization pathway for Ph 3Si≡CCF3, initiated by t-BuLi, that yields the respective gem-difluorocyclopropene has been explored and is described in detail, along with its extension to a number of other systems.
- Brisdon, Alan K.,Crossley, Ian R.,Pritchard, Robin G.,Sadiq, Ghazala,Warren, John E.
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p. 5534 - 5542
(2008/10/09)
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