Grafting onto a renewable unsaturated polyester via thiol–ene chemistry and cross-metathesis

Methyl 10-undecenoate was modified to its corresponding malonate derivative by the reaction with sodium hydride in dimethyl carbonate. This malonate was then polymerized with 1,6-hexanediol, catalyzed by 1.0 mol% titanium (IV) isopropoxide, to a poly(malonate) bearing C9 aliphatic side-chains with terminal double bonds. The double bonds of this poly(malonate) were used for grafting onto reactions by either ruthenium-catalyzed cross-metathesis reactions with acrylates or thiol–ene addition reactions. Several examples are shown for both methods. For the cross-metathesis reactions, 1.0 mol% Hoveyda–Grubbs 2nd generation (HG II) catalyst was used with 10.0 equivalents of the respective acrylate under bulk conditions at 40 °C. The thiol–ene additions were carried out with 1.0 equivalents of the respective thiol in THF with 5.0 mol% 2,2-Dimethoxy-2-phenylacetophenone (DMPA) under UV (365 nm) irradiation. Moreover, we have shown that a carboxylic acid group can be easily installed via thiol–ene addition and that the resulting polymer can be further modified by the Passerini three-component reaction with quantitative conversion.