The reaction of cysteine (I) with benzyl chloroformate (II) in the usual way gives the corresponding di(benzyloxycarbonyl) derivative (III), which is treated with PCl5 or SOCl2 in CHCl3 to afford the bisacyl chloride (IV). Finally, this compound is condensed with 4,6-dibromo-2-(cyclohexylmethylaminomethyl) aniline (V) in ethyl acetate.