Lewis base-catalyzed diastereoselective Strecker-type reaction between trimethylsilyl cyanide and chiral sulfinimines derived from commercially available (S)-(+)-p-toluenesulfinamide and aliphatic aldehydes proceeded smoothly by using a catalytic amount of tetra-n-butylammonium acetate in DMF to afford the corresponding alpha-amino nitriles with (Ss,R)-configurations in good to high yields and diastereoselectivities.