928292-08-4Relevant articles and documents
The palladium-catalyzed aerobic kinetic resolution of secondary alcohols: Reaction development, scope, and applications
Ebner, David C.,Bagdanoff, Jeffrey T.,Ferreira, Eric M.,McFadden, Ryan M.,Caspi, Daniel D.,Trend, Raissa M.,Stoltz, Brian M.
supporting information; experimental part, p. 12978 - 12992 (2010/06/19)
The first palladium-catalyzed enantioselective oxidation of secondary alcohols has been developed, utilizing the readily available diamine (-)-sparteine as a chiral ligand and molecular oxygen as the stoichiometric oxidant. Mechanistic insights regarding the role of the base and hydrogen-bond donors have resulted in several improvements to the original system. Namely, addition of cesium carbonate and tert-butyl alcohol greatly enhances reaction rates, promoting rapid resolutions. The use of chloroform as solvent allows the use of ambient air as the terminal oxidant at 23°C, resulting in enhanced catalyst selectivity. These improved reaction conditions have permitted the successful kinetic resolution of benzylic, allylic, and cyclopropyl secondary alcohols to high enantiomeric excess with good-toexcellent selectivity factors. This catalyst system has also been applied to the desymmetrization of meso-diols, providing high yields of enantioenriched hydroxyketones.
