Synthesis of cyclic and multicyclic polyisoprenes |
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Authors: | Jean-Marc BoutillierBénédicte Lepoittevin Jean-Claude Favier†Michèle Masure Patrick Hémery Pierre Sigwalt |
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Institution: | Laboratoire de Chimie des Polymères associé au CNRS, UMR 7610, Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cédex 05, France |
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Abstract: | Cyclic polyisoprenes have been synthesized by reaction of α,ω-dilithiopolyisoprenes with dichlorodimethylsilane or 1,2-bis(isopropenyl-4-phenyl) ethane (BIPE). Using the dihalide compound, the effect of the solvent polarity on the coupling reaction is more pronounced in the case of α,ω-dilithiopolyisoprene than with monofunctional polyisoprenyllithium. The yield in cyclic compound falls from 88% in pure hexane down to 53% in the presence of 15 vol% of tetrahydrofurane (THF). Using the nonconjugated diene (BIPE) as linking agent the addition of THF is required but the formed cycle retains its living character and allows the synthesis of cycles having two arms (after addition of isoprene) and of a bicyclic structure after a second cyclization reaction. |
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