Generation of well-defined clickable glycopolymers from aqueous RAFT polymerization of isomaltulose-derived acrylamides

Original carbohydrate-based acrylamides bearing one azide group in C-2 or C-6 position namely, 2-[(2-deoxy-2-azido-alpha-D-mannopyranosyloxy)ethanamidol-ethyl acrylamide (II) and 24(6-deoxy-6-azido-alpha-D-glucopyranosyloxy)ethanarnido]-ethyl acrylamide (III), and their azide-free analogue, 2-((alpha-D-glucopyranosyloxy)ethanamidol-ethyl acrylamide (I), have been designed. Whereas the reversible addition fragmentation chain transfer (RAFT) process ensured the preparation of well-defined glycopolymers from I, the polymerization of moanomers II and III proved to be challenging at temperatures compatible with a thermally initiated radical process, due to the presumed concomitant 1,3-cycloaddition reactions between the azide and the acrylamide moieties. In contrast to III, for which no polymer could be obtained under any conditions, performing the RAFT polymerization of II at 30 C clearly favored the radical polymerization and conferred a controlled character to the process, affording well-defined azide-functionalized glycopolymers and block copolymers. The presence of numerous azide moieties was finally exploited to introduce carbohydrates onto the glycopolymer backbone through copper catalyzed azide-alkyne cycloaddition.