Synthesis of Side-Chain Functional Polyesters via Baylis-Hillman Polymerization

Strategies that allow access to side-chain functional polyesters are valuable as they would enable to engineer the properties of these hydrolytically degradable materials. This contribution explores the feasibility of a novel approach toward side-chain functional polyesters that is based on the Baylis-Hillman reaction, which involves the base-catalyzed condensation of an aldehyde and an acrylate building block to produce an alpha-methylene-beta-hydroxycarbonyl compound. Using 1,3-butanediol acrylate and 2,6-pyridinecarboxaldehyde as monomers and DABCO as catalyst, polymers with a degree of polymerization of up to 25 could be prepared. These polymers are attractive as they contain chemically orthogonal side-chain hydroxyl and vinyl groups that can be further modified. In the first experiments, it was demonstrated that the side-chain hydroxyl and vinyl groups can be quantitatively postmodified with phenyl isocyanate and methyl-3-mercaptopropionate, respectively. As the Baylis-Hillman polymerization does not require the use of side-chain protected monomers, this route may represent an interesting alternative strategy for the preparation of side-chain functional polyesters.