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Enantioselectivity in the Iridium-Catalyzed Hydrogenation of Unfunctionalized Olefins

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journal contribution
posted on 27.12.2010, 00:00 by Tamara L. Church, Torben Rasmussen, Pher G. Andersson
The iridium-catalyzed asymmetric hydrogenation of largely unfunctionalized olefins has been studied by DFT calculations using a full, experimentally tested combination of ligand and substrate. All possible diastereomeric pathways were considered within four different hydrogenation mechanisms. The effect of a solvent continuum was also considered, and both the gas-phase and solvent-continuum calculations favored the same mechanism. This mechanism passed through IrIII and IrV intermediates and was consistent with the sense of stereoselection observed experimentally. Comparing the calculations to those performed on a model system permitted an evaluation of the model system’s utility in representing the full one. A simple, general method for predicting the sense of stereoselection in iridium-catalyzed olefin hydrogenation was developed and tested against published data.