Controllable glycosylation of polyphosphazene via radical thiol-yne click chemistry

We describe a versatile approach to synthesize glycosylated polyphosphazenes with controllable density of glycosyl groups. These glycopolymers have been synthesized by the nucleophilic substitution of poly(dichlorophosphazene) with propargylamine and subsequent thiolyne click reaction between poly[di(propargylamine)phosphazene] and 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose (SH-GlcAc4). The polymers were characterized with FTIR and 1H NMR. We found that the high steric hindrance of SH-GlcAc4 plays a key role in the overall reaction process, and similar to 55% of the alkyne groups participate in the thiolyne click reaction. About 8% of the alkyne groups convert to alkene groups at the end of click reaction. The substitution of alkyne/alkane mixture was conducted to reduce the alkyne density in the side groups of polyphosphazenes and minimize the influences of this steric effect. Mixed-substituent polyphosphazene was synthesized with 2:3 ratio of alkyne and alkane. In this case, almost no alkyne group remains after the thiolyne click reaction, and thus the glycosylated polyphosphazene is able to form into micelles through self-assembly process. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012