Dipeptide 14 was prepared following general peptide coupling procedure A, using Z-L-Ser as the amino acid and readily available 5-amino-1-pentene trifluoroacetate (Supporting Information) as the amine. The crude product was purified by flash chromatography on a silica gel column (eluent 70:30 EtOAc-hexanes) to give the product as a white solid (78%