The first application of cinchona thioureas as organocatalysts in an oxidative process has been disclosed. Specifically, cinchona thioureas/tert-butyl hydroperoxide was found to be an effective system for an unprecedented asymmetric epoxidation of highly challenging deactivated 1,1-disubstituted alkenes. The corresponding terminal epoxides, bearing a quaternary stereogenic center, have been isolated in good to excellent yield (up to 98%) and enantioselectivity (up to 99% ee) by using 5 or 10 mol% of the organocatalyst.
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