Asymmetric Hydrogenation of tert-Alkyl Ketones
T. Ohkuma, C. A. Sandoval, R. Srinivasan, Q. Lin, Y. Wei, K. Muñiz, R. Noyori*
Nagoya University, Japan
21 September 2005 (online)
Success with highly hindered tert-alkyl ketones remained an elusive element to the ruthenium-catalyzed hydrogenation reaction. The authors have overcome this problem by replacing the normally used symmetric 1,2-diamine or bipyridine with an unsymmetrical pyridine/NH2 hybrid ligand and ethanol as solvent. The reaction proceeds at room temperature, 1-20 atm with an S/C ratio of 100,000.