Synthesis of an Amphiphilic β‑Turn Mimetic Polymer Conjugate

A new biomimetic polymer containing a beta-turn mimetic element (1) was synthesized, using a combination of living carbocationic polymerization (LCCP), amidation, and “click” chemistry. Two different α-ω-functionalized polyisobutylenes (PIBs 3 and 5) bearing either an alkyne group (PIB 3) or a primary amine group (PIB 5) were directly synthesized via LCCP. The linking of the two PIB strands with the closely positioned carboxyl/azido moieties of a β-turn dipeptide (BTD) 2 was achieved via a sequence of amidation reaction and the Cu^I-mediated azide/alkyne “click” reaction. By means of size exclusion chromatography (SEC), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), NMR spectroscopy, and LC/MALDI-TOF MS, a detailed structural proof of the β-turn mimetic PIB conjugate (1) was possible.