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Rh-Catalyzed Asymmetric Addition of Trifluoroborates to SulfonylketiminesContributor(s):Paul Knochel, Andreas J. Wagner
Kyoto University, Japan
Rhodium-Catalyzed Asymmetric Addition of Potassium Organotrifluoroborates to N-Sulfonyl Ketimines
Org. Lett. 2011, 13: 2977-2979
19 August 2011 (online)
rhodium - asymmetric synthesis - trifluoroborates - ketimines
Easily accessible potassium organotrifluoroborates undergo a rhodium-catalyzed asymmetric addition to both N-tosyl and N-nosyl ketimines. The use of a chiral bicyclooctadiene-based ligand allows high enantiomeric excess in the product formation.
In the case of nosyl groups, the addition products can easily be deprotected using thiophenolpotassium carbonate, retaining the enantiomeric purity. For related applications of dienic ligands, see: K. Okamoto, T. Hayashi, V. H. Rawal Org. Lett. 2008, 10, 4387.