Intriguing Behavior of Cinchona Alkaloids in the Enantioselective Organocatalytic Hydroxyamination of α-Substituted-α-cyanoacetates

The cinchona alkaloid quinine promotes the enantioselective
nitroso-aldol reaction between α-aryl-α-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.