Intriguing Behavior of Cinchona Alkaloids in the Enantioselective Organocatalytic Hydroxyamination of α-Substituted-α-cyanoacetates
摘要:
The cinchona alkaloid quinine promotes the enantioselective nitroso-aldol reaction between alpha-aryl-alpha-cyanoacetates and nitrosobenzene to give the hydroxyamination products with total chemoselectivity. Treatment of the reaction mixture with Zn/AcOH affords the corresponding amines in high yield and moderate enantioselectivity. An unusual effect on the enantioselectivity was observed with the catalyst loading and solvent. A reductive protocol allows the construction of an optically active 1,2-diamine moiety bearing a quaternary center.