Electrochemical thioester synthesis enabled by phosphine promotion from carboxylic acids and disulfides

Thioesters serve as important pharmacophores and synthetic intermediates, yet their conventional synthesis typically requires high temperatures, transition metal catalysts, or toxic and malodorous thiols. Herein, we present a simple and green electrochemical approach for the thioesterification of carboxylic acids with aromatic disulfides as direct sulfur surrogates, promoted by triphenylphosphine. The reaction proceeds under mild conditions without requiring transition metals, external reducing agents, or inert atmosphere. A broad scope of aromatic, aliphatic, and heterocyclic carboxylic acids, along with diversely substituted aromatic disulfides, are well tolerated, affording the corresponding thioesters in moderate to excellent yields. Gram‑scale synthesis and downstream derivatization demonstrate the practical utility of this protocol. Mechanistic studies support a radical-radical cross‑coupling pathway. This work offers a scalable and environmentally benign alternative for thioester synthesis.