Deoxygenation of Epoxides with Carbon Monoxide |
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Authors: | Theo Maulbetsch Dr. Eva Jürgens Prof. Dr. Doris Kunz |
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Affiliation: | Institut für Anorganische Chemie, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany |
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Abstract: | The use of carbon monoxide as a direct reducing agent for the deoxygenation of terminal and internal epoxides to the respective olefins is presented. This reaction is homogeneously catalyzed by a carbonyl pincer-iridium(I) complex in combination with a Lewis acid co-catalyst to achieve a pre-activation of the epoxide substrate, as well as the elimination of CO2 from a γ-2-iridabutyrolactone intermediate. Especially terminal alkyl epoxides react smoothly and without significant isomerization to the internal olefins under CO atmosphere in benzene or toluene at 80–120 °C. Detailed investigations reveal a substrate-dependent change in the mechanism for the epoxide C−O bond activation between an oxidative addition under retention of the configuration and an SN2 reaction that leads to an inversion of the configuration. |
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Keywords: | deoxygenation epoxides homogeneous catalysis iridium pincer ligands |
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