Radical additions to fluoro-olefins. Photochemical mono-fluoroalkylation and sequential bis-fluoroalkylation of oxolane

Article abstract of DOI:10.1016/S0022-1139(96)03511-7

Oxolane was fluoroalkylated by its photoadditions under atmospheric pressure. Monofluoro-alkylations were carried out with hexafluoropropene (1) and perfluorovinyl ethers C₃F₇O-[CF(CF₃)CF₂O]_n-CF=CF₂ (2-4, n=0-2) by direct photoexcitation of the oleflns to give high yields of addition products 9-12 (81-94%). The reactions were completely regioselective at the oxolane molecule and almost completely regioselective (93-99%) at the double bond of fluoro-olefins; no bis-fluoroalkylated oxolanes were detected. The completely selective introduction of a second fluoroalkyl into position 5 of the oxolane molecule was accomplished by acetone-sensitised photoaddition of 2-fluoroalkylated oxolanes 9, 10 to fluoro-olefins 1 and 2. Byproducts from reactions of the dimethylketyl radical which is formed in the initiation step were isolated and have given some evidence about the reaction mechanism that is discussed.