Radical additions to fluoro-olefins. photochemical mono-fluoroalkylation and sequential bis-fluoroalkylation of oxolane |
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Authors: | Old?ich Paleta Vladimír Církva Jaroslav Kvicala |
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Institution: | Department of Organic Chemistry, Prague Institute of Chemical Technology, Technická 5, 16628 Prague 6, Czech Republic |
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Abstract: | 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 (24, n = 0–2) by direct photoexcitation of the olefins to give high yields of addition products 9–12 (81–94%). The reactions were completely regioselecti ve 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 2fluoroalkylated 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. |
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Keywords: | Radical addition Regioselectivity Perfluoroolefins Oligomerisation of hexafluoropropene-1 2-oxide Perfluorovinyl ethers Photo-addition Sensitised photoaddition 2-(Fluoroalkyl)oxolanes 2 5-bis(Fluoroalkyl)oxolanes Diastereoisomers |
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