A solution of thioacetic acid S-[3-benzylsulfanyl-2-(cyanomethyl-carbamoyl)propyl] ester (0.105 g) in dimethylformamide (1 mL) and water (0.8 mL) was cooled on ice and treated with 1 N aqueous potassium hydroxide (0.65 mL). 3-Cyanobenzylbromide (0.129 g) in dimethylformamide (0.8 mL) was added. The reaction mixture was allowed to warm to room temperature while stirring overnight. The reaction mixture was then poured into ice water and extracted with ethyl acetate (50 mL) and washed with water and saturated aqueous sodium chloride. The solution was dried over magnesium sulfate and evaporated to give 2-benzylsulfanylmethyl-3-(3-cyano-benzylsulfanyl)-N-cyanomethyl-propionamide (0.135 g).
