Synthesis of Fluorinated Acetylenes

Article abstract of DOI:10.1021/jo00133a003

New routes to fluorinated acetylenes were developed on the basis of additions of iodofluorocarbons to silylacetylenes.Free radical addition of α,ω-diiodoperfluoroalkanes to (trimethylsilyl)acetylene gave the iodotrimethylsilyl olefins Me3SiIC=CH(CF2)nCH=CISiMe3, which reacted with potassium tert-butoxide or DBU to give the (trimethylsilyl)acetylenes and, with an excess of the base, the free diacetylenes.Perfluoroalkyl iodides similarly gave (perfluoroalkyl)acetylenes.The addition of perfluoroheptyl iodide to phenylacetylene, followed by treatment with potassium tert-butoxide gave 1-phenylperfluorononyne.The peroxide-catalyzed reactionof perfluoroalkyl iodides and bis(trimethylsilyl)acetylene gave 1:1 adducts, R_F(Me2SiCH2I)C=CHSiMe3, resulting from intramolecular hydrogen abstraction by the initially formed vinyl radical.However, the thermal reaction of perfluoroalkyl iodides and diiodides with bis(trimethylsilyl)acetylene in the presence of free iodine gave the (trimethylsilyl)acetylenes, which were desilylated with potassium fluoride.A route to diacetylenes was investigated on the basis of addition of perfluoroiodo compounds to ethylene, dehydroiodination, brominations, and eliminations.