CONTROLLED/LIVING POLYMERIZATIONS OF CYCLIC AND VINYL MONOMERS DERIVED FROM AMINO ACIDS

1These synthetic polymers can be useful as chiral recognition stationary phases, asymmetric catalysts, metal ion absorbents, drug-delivery agents, and biocompatible materials. In recent years, much interest has been devoted to develop novel approaches for the preparation of minics of these natural macromolecules as well as artificial polypeptides for various biorelated applications. We report here controlled/living polymerizations of cyclic and vinyl monomers derived from amino acids. The synthesis of well-defined polyacrylamides having amino acid moieties in the side chains was conducted by reversible addition-fragmentation chain transfer (RAFT) polymerization. The cationic ring-opening polymerization of chiral cyclic thiourethanes derived from serines was employed for the synthesis of novel optically active amino acid-based polymers. Results and Discussion RAFT Polymerization. Three acrylamides, N-acryloyl-L-phenylalanine methyl ester (A-Phe-OMe), N-acryloyl-L-phenylalanine (A-Phe), and Nacryloyl-L-proline methyl ester (A-Pro-OMe), were selected as amino acidcontaining monomers. Among controlled radical polymerizations, RAFT process has been successfully applied for controlled polymerization of acrylamide derivatives. These results confirm the ability of the RAFT technique to produce well-controlled polymer chains either from monosubstituted or disubstituted acrylamide derivatives with narrow molecular weight distribution. In this study, two different chain transfer agents, benzyl 1-pyrrolecarbodithioate (CTA 1) and benzyl dithiobenzoate (CTA 2), were employed for the RAFT polymerization of these acrylamides containing amino acid moieties.