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Fluorodemetalation reactions of organogermanium, -tin and lead compounds

McGill University
Publication Date
  • Chemistry
  • Organic.
  • Design


Fluoride ions smoothly destannylate organotin oxides, sulfides and selenides to liberate highly nucleophilic species ("S$ sp{2-}$", RS$ sp-$, RO$ sp-$, RSe$ sp-$, etc.). Also, the first nucleophilic oxide "O$ sp{2-}$" and selenide "Se$ sp{2-}$" transfer agents are reported. The tin atom thus serves as a general "group 16 (VIB) transfer agent". In the presence of crown ethers or ammonium salts, this process results in a new way to generate "naked" nucleophiles. Novel anhydrous fluorinating systems (CsF and crown ethers) involving solid-liquid phase transfer catalysis have been designed and studied. In addition, C-C bond forming reactions have been investigated by fluorodestannylation. As an extension of these results, fluorodegermanylation and fluorodeplumbylation reactions are reported. As a generalization, fluoride ion demetalates the whole group 14 for releasing nucleophilic species. Some pentacoordinated intermediates have been observed by $ sp{19}$F and $ sp{119}$Sn NMR spectroscopy in fluorodestannylation, thus confirming the model of nucleophilic substitution at tin and silicon. Mechanistic aspects are discussed along with a possible metal proximity effect in the enhancement of the nucleophilicity of an anion. Finally, in the presence of silver salts, bis(tributyltin) oxide acts as a mild oxygen transfer agent in converting primary organic iodides and bromides to alcohols.

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