β,β-Disubstituted enesulfinamides undergo stereoselective nucleophilic addition to the formaldehyde imines, in situ formed from tosylmethylcarbamates, affording α-aminomethylated ketimines bearing a challenging acyclic quaternary stereocenter substituted by two sterically and electronically similar groups (e.g., Me and Et). The defined geometry of the C═C bond in the enesulfinamides, combined with the strong chiral induction offered by their chiral sulfinyl group, ensures precise stereocontrol during the formation of the new C-C bond.