Synthesis of the pentafluorophenyl ester dye intermediates 11 required to synthesize the dye-modified CPG supports 12 is shown in Scheme 2. Compounds 4a and b were reacted with substituted phthalic anhydrides in the presence of AlCl 3 to give the benzophenones 5, which were reacted with the resorcinol analogs 6 (a-c) in trifluoroacetic acid/ methanesulfonic acid to yield the carboxyethyl substituted dyes 7. Treatment of compounds 7 with trifluoroacetic anhydride generated lactones 8, which were first reacted with the DMT-protected hydroxyprolinol 9 (21) and then with trimethylacetic anhydride to afford the protected dyes 10. Reaction of intermediates 10 first with succinic anhydride and then with pentafluorophenyl trifluoroacetate, yielded the PFP esters 11.