Pd-Catalyzed Asymmetric Allylic Alkylation of Carboxylic Acids for the Synthesis of Chiral Butenolidyl Ester Prodrugs and Peptide-Drug Conjugates.

A Pd-catalyzed asymmetric allylic alkylation of γ-OBoc-butenolides with carboxylic acids enables the direct synthesis of chiral γ-substituted butenolides under mild conditions. The reaction proceeds with broad substrate scope and excellent stereocontrol, tolerating diverse carboxylic acids including those derived from natural products, pharmaceuticals, and peptides. The resulting chiral butenolidyl esters serve as valuable prodrug scaffolds and peptide-drug conjugation units, offering a new asymmetric strategy for the construction of stereodefined bioconjugates and chiral prodrugs.