Synthesis and helical conformation of poly(N‐propargylamides) carrying L‐aspartic acid in the side chain

Abstract

AbstractAspartic acid‐based novel poly(N‐propargylamides), i.e., poly[N‐(α‐tert‐butoxycarbonyl)‐L‐aspartic acid β‐benzyl ester N′‐propargylamide] [poly(1)] and poly[N‐(α‐tert‐butoxycarbonyl)‐L‐aspartic acid α‐benzyl ester N′‐propargylamide] [poly(2)] with moderate molecular weights were synthesized by the polymerization of the corresponding monomers 1 and 2 catalyzed with (nbd)Rh+[η6‐C6H5B−(C6H5)3] in CHCl3 at 30 °C for 2 h in high yields. The chiroptical studies revealed that poly(1) took a helical structure in DMF, while poly(2) did not in DMF but did in CH2Cl2, CHCl3, and toluene. The helicity of poly(1) and poly(2) could be tuned by temperature and solvents. Poly(2) underwent solvent‐driven switch of helical sense, accompanying the change of the tightness. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5168–5176, 2005