Sequential polypeptides by matrix‐controlled thermal polymerization. Synthesis and racemization studies

A new method for the synthesis of sequential polypeptides is described. The approach consists of the thermal condensation in vacuo of the trifluoroacetate salts of tripeptide pentachlorophenyl esters deposited on a micron‐size celite matrix. The synthesis and polymerization of the trifluoroacetate salts of L‐valy‐L‐valyl‐L‐alanine pentachlorophenyl ester, glycyl‐L‐valyl‐L‐alanine pentachlorophenyl ester, and L‐valyl‐L‐alanylglycine pentachlorophenyl ester are described. High‐molecular‐weight polymers are obtained rapidly in high yield by this method. Comparison of the extents of racemization in the last two polymers constitutes a general approach for assessing racemization during the synthesis of sequential polypeptides since both yield the same polymer, but only the C‐terminal alanine may recemize in the former case.