Synthesis of an Amphiphilic β-Turn Mimetic Polymer Conjugate

Abstract

A new biomimetic polymer containing a beta-turn mimetic element (<b>1</b>) was synthesized, using a combination of living carbocationic polymerization (LCCP), amidation, and "click" chemistry. Two different α-ω-functionalized polyisobutylenes (PIBs <b>3</b> and <b>5</b>) bearing either an alkyne group (PIB <b>3</b>) or a primary amine group (PIB <b>5</b>) 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) <b>2</b> 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 (<b>1</b>) was possible.