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Intramolecular Pauson-Khand Reactions with Ir(phox) Catalysts
Z.-L. Lu, E. Neumann, A. Pfaltz*
University of Basel, Switzerland
22 November 2007 (online)
The Pfaltz group has extended their work with phosphane oxazoline (phox) ligands to include asymmetric induction in the Pauson-Khand reaction. Moderate to high ee values were obtained for a limited number of substrates. The main focus of the paper was the optimization of conditions for the reaction. CO pressure, catalyst loading, and counteranion effect were studied. A pressure of 2.2 bar was determined to be the best CO pressure in terms of yield and ee, while tetrafluoroborate, hexafluorophosphate, and triflate proved to be some of the better counteranions.