Journal of the American Chemical Society, Vol.137, No.50, 15612-15615, 2015
Design of a New Bimetallic Catalyst for Asymmetric Epoxidation and Sulfoxidation
A new chiral tethered 8-quinolinol-based ligand class is developed. The binuclear titanium complex of the ligand operates through a novel mechanism allowing for the regio- and stereoselective epoxidation of primary and tertiary homoallylic alcohols (up to 98% ee), as well as first examples of 2-allylic phenols (up to 92% ee). The new catalyst system also promotes the asymmetric oxidation of gamma-hydroxypropyl sulfides giving an important class of chiral sulfoxides that have been inaccessible to date (up to 95% ee).