Introduction of (S)-configuration is the key step in the synthesis of the anti-dementia drug Rivastigmine. Twenty-one alkylation products were obtained through simple washing with hexane/ethyl acetate (v/v: 10/1) in good yields (> 85%) and high diastereoselectivity (up to > 99: 1 dr). Moreover, the chiral auxiliary could be easily dissociated and readily regenerated. That is, the synthesis was proved to follow group-assisted purification (GAP) chemistry/technology. In addition, the chiral amine produced by this asymmetric alkylation reaction was effectively used in the synthesis of Rivastigmine.