A Series of Cinchona-Derived N-Oxide Phase-Transfer Catalysts: Application to the Photo-Organocatalytic Enantioselective alpha-Hydroxylation of beta-Dicarbonyl Compounds

摘要

A series of cinchona-derived N-oxide asymmetric phase-transfer catalysts were synthesized and applied in the enantioselective photo-organocatalytic alpha-hydroxylation of beta-keto esters and beta-keto amides (23 examples) using molecular oxygen in excellent yields (up to 98%) and high enantioselectivities (up to 83% ee). These new catalysts could be recycled and reused six times for such a reaction with almost the original reactivity and enantioselectivity.