Diol (I) was protected as the isopropylidene ketal (III) by reaction with 2,2-dimethoxypropane (II) and p-toluenesulfonic acid. Then, the N-carbobenzoxy groups of (III) were eliminated by hydrogenolysis on Pd/C to give the diamine (IV), and this was coupled with N-carbobenzoxy-valine (V) using O-benzotriazol-1-yl-tetramethyluronium hexafluorophosphate (HBTU) to afford (VI). A new sequence of hydrogenolytic Cbz deprotection to give diamine (VII) and coupling with N-carbobenzoxy-alanine (VIII) and HBTU provided (IX). Finally, the target compound was obtained by hydrolysis of the isopropylidene ketal in methanol containing p-toluenesulfonic acid.