α-Hydroxylation of α,α-Disubstituted N - tert -Butanesulfinyl Ketimines with Molecular Oxygen: Stereoselective Synthesis of α-Tertiary Hydroxyimines.

α-Tertiary hydroxyimines were stereoselectively synthesized from enantioenriched N - tert -butanesulfinyl ketimines using potassium tert -butoxide, molecular oxygen, and trimethyl phosphite. The stereoselective hydroxylation of acyclic ketimines bearing two sterically similar α-substituents was achieved by controlling the geometry of the metalloenamine intermediates and the facial selectivity of hydroxylation. The synthetic utility of the resulting α-tertiary hydroxyimines was demonstrated through the successful diastereoselective synthesis of highly substituted β-amino alcohols.