PETR 11 |
| The epoxidation of simple unfunctionalyzed terminal alkenes such as propene, 1-hexene, 1-octene, etc. has always been very challenging because of their intrinsically poor reactivity. Devising new catalysts capable of activating the substrate instead of the oxidant is crucial. We report the preparation of new soft Pt(II) Lewis acid catalysts that show exceptional activity in such reaction using H2O2 as the oxidant. Unprecedented selectivity is observed in the epoxidation of dienes (terminal and internal double bonds). Enantioselectivities up to 87% are observed using chiral-diphosphine modified catalysts. mechnistic insight shows that the reaction proceeds via direct activation of the olefin by the metal, followed by nucleophilic attack of the oxidant. |
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Mechanism in Homogeneous and Heterogeneous Catalytic Epoxidation
8:15 AM-12:00 PM, Sunday, August 19, 2007 Boston Park Plaza -- Whittier Rm, Oral
Division of Petroleum Chemistry |