Preparation of Ala-containing analog 2b proceeded smoothly as outlined in Scheme 2. Dehydration of the dipeptide Cbz-Ser-Pro-OMe ( ) was accomplished by mesylation of the primary alcohol followed by exposure to DBU and heat. No racemization of the Pro residue was detected under these conditions. Saponification of the resulting Ala-containing dipeptide and coupling with dipeptide 4 delivered 2b in a reasonable yield considering the hindered nature of the reactants.