Reductive Amination/Cyclization of Methyl Levulinate with Aspartic Acid: Towards Renewable Polyesters with a Pendant Lactam Unit

Environmental regulation and depletion of fossil resources are boosting the search for new polymeric materials produced from biomass. Here, the synthesis of a new diester bearing a pendant lactam unit from methyl levulinate and aspartic acid is reported. The palladium‐catalyzed reductive amination/cyclization sequence was carefully optimized to afford the diacid with high yield (>95 %). In a second step, the compound was esterified to give the corresponding diester. The latter monomer was copolymerized with α–ω linear diols, yielding polyesters with molecular weights up to 20.5 kg mol−1. Biobased polyesters: The renewable building blocks aspartic and levulinic acid are combined by a catalytic reductive amination/cyclization process to yield a new diester. The latter is copolymerized with biobased diols to obtain fully biobased polyesters with a pendant rigid lactam unit.