BF3-mediated additions of organolithiums to ketimines:: X-ray crystal structures of BF3-ketimine complexes

Additions of lithium acetylides and n-BuLi to N-alkyl ketimines mediated by BF3-Et2O in THF afford hindered tert-alkylamines in moderate to good yields. Stereochemical results and crystal structures of three BF3-imine complexes suggest that allylic strain strongly influences conformation and may be an important determinant of reactivity and selectivity.