Asymmetric Hydrogenation with Highly Active IndolPhos–Rh Catalysts: Kinetics and Reaction Mechanism |
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| Authors: | Jeroen Wassenaar Mark Kuil Dr Martin Lutz Dr Anthony L Spek Prof Dr Joost N H Reek Prof Dr |
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| Institution: | 1. Supramolecular & Homogeneous Catalysis van ‘t Hoff Institute for Molecular Sciences', University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam (The Netherlands), Fax: (+31) 20 5255604;2. BASF Nederland B.V. Catalysts, Strijkviertel 67, 3454 PK De Meern (The Netherlands),;3. Crystal and Structural Chemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht (The Netherlands);4. Current address: Solvay Pharmaceuticals |
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| Abstract: | The mechanism of the IndolPhos–Rh‐catalyzed asymmetric hydrogenation of prochiral olefins has been investigated by means of X‐ray crystal structure determination, kinetic measurements, high‐pressure NMR spectroscopy, and DFT calculations. The mechanistic study indicates that the reaction follows an unsaturate/dihydride mechanism according to Michaelis–Menten kinetics. A large value of KM (KM=5.01±0.16 M ) is obtained, which indicates that the Rh–solvate complex is the catalyst resting state, which has been observed by high‐pressure NMR spectroscopy. DFT calculations on the substrate–catalyst complexes, which are undetectable by experimental means, suggest that the major substrate–catalyst complex leads to the product. Such a mechanism is in accordance with previous studies on the mechanism of asymmetric hydrogenation reactions with C1‐symmetric heteroditopic and monodentate ligands. |
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| Keywords: | asymmetric catalysis hydrogenation kinetics reaction mechanisms rhodium |
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