Tandem Catalysis as a Platform for the Mild Synthesis of Renewable Aliphatic Polyanhydrides

The development of one-pot catalytic strategies that transform renewable feedstocks into functional polymers remains an important challenge in sustainable polymer chemistry. Here, we report a tandem-catalyzed strategy for the mild step-growth polymerization of a fatty acid-derived monomer into high-molar-mass aliphatic polyanhydrides. Selective ruthenium-catalyzed self-metathesis of 10-undecenoic acid affords eicos-10-enedioic acid with high conversion and minimal olefin positional isomerization within the substrate. The resulting diacid is subsequently converted into a polyanhydride through magnesium-catalyzed dehydrative polycondensation using dimethyl dicarbonate as a stoichiometric dehydrating reagent. The two catalytic transformations are operationally compatible and can be performed as a sequential one-pot process without isolation of the diacid intermediate. The orthogonal Ru/Mg sequence affords polyanhydrides with weight-average molar masses above 30 kg/mol, while the independently optimized magnesium-catalyzed polymerization reaches weight-average molar masses above 80 kg/mol. A ruthenium species derived from the metathesis catalyst can also promote the dehydrative coupling step, providing an auto-tandem pathway, although with lower molar-mass control. The resulting polyanhydride films exhibit water contact angles of 95°-100°, within the range reported for polyethylene and polypropylene surfaces. This work establishes a mild and step-efficient route from a renewable unsaturated fatty acid to hydrophobic aliphatic polyanhydrides.