Synthesis of Optically Active beta-Amino Acid N-Carboxyanhydrides.
Methodology has been developed for the general synthesis of optically active beta-amino acid N-carboxyanhydrides (beta-NCAs) through cyclization of N(beta)-Boc or N(beta)-Cbz beta-amino acids using phosphorus tribromide. The formation of beta-NCAs was confirmed by spectroscopy as well as an X-ray structural determination of beta-homoalanine-N-carboxyanhydride. The beta-NCA molecules could be polymerized in good yield to give optically active poly(beta-peptides) that adopt stable chiral conformations in solution. For example, helical oligo(L-beta-homophenylalanine) was synthesized by polymerization of L-beta-homophenylalanine-N-carboxyanhydride.
Cheng
J
Departments of Materials and Chemistry, University of California, Santa Barbara, Santa Barbara, California 93106, and Department of Chemistry, University of California, Irvine, California 92697.
Ziller
JW
Deming
TJ