Phosgene-free synthesis of polypeptides using activated urethane derivatives of α-amino acids: an efficient synthetic approach to hydrophilic polypeptides
series of polypeptides have been synthesized from the corresponding N-phenoxycarbonyl derivatives of hydroxyl- or amino-functionalized α-aminoacids such as L-serine, L-cysteine, L-threonine, L-tyrosine, L-glutamine, and L-asparagine. These derivatives are prepared by N-carbamylation of tetrabutylammonium salts of α-aminoacids with diphenyl carbonate (DPC). The synthesis of polypeptides can be achieved