Seventeen examples of aza-Morita–Baylis–Hillman (aza-MBH) adducts have been synthesized by reacting chiral N-phosphonyl imines with acrylonitrile in good to excellent yields (up to 96%) and high diastereoselectivity (up to 99:1 dr). The synthesis of these adducts followed the method of group-assisted purification (GAP) chemistry, in which the pure aza-MBH products were readily obtained by washing the crude products with cosolvents of hexane and ethyl acetate.