Asymmetric oxohydroxylation of α-alkyl enoates with potassium permanganate catalyzed by monocationic quaternary...
Cupreine (CAS-No. 524-63-0) as well as its pseudoenantiomer Cupreidine are highly enantioselective bifunctional Cinchona organocatalysts. They can be used for a wide range of asymmetric reactions such as Michael additions, Mannich, Henry, Friedel-Crafts, reactions etc..
Cleavage of the C6′ methoxy group in Cinchona Alkaloids affords organocatalysts with a phenolic OH group. Despite its position far away from the stereocenters, this hydroxy group proves crucial to obtain high enantioselectivity in many synthetically relevant reactions like Michael additions. The electrophile is activated via the C6`-hydroxy group. On the other hand the free C6’ hydroxy group can be further functionalized to improve catalytic performance. Deprotonation of the phenolic OH group and quaternization of the quinuclidine nitrogen leads to enantioselective Cinchonium bataines being highly efficient (99 % ee) as catalysts in asymmetric proton transfer catalysis such as imine isomerization.