Transition-metal-free Csp–Csp doubly decarboxylative coupling of amino acids and propiolic acids

A3-coupling and decarboxylative A3-coupling is an important protocol for constructing propargylamines. However, the development of metal-free (decarboxylative) A3-coupling is still challenging. Herein, we describe a doubly decarboxylative coupling of amino acids, propiolic acids, and aldehydes under metal-free conditions. It is worth noting that choosing the kind of aldehydes is crucial for controlling the chemoselectivity of the reaction. The use of glyoxylate ester furnished ester-containing propargylamines in good yield via a cascade process of decarboxylation and decarboxylative coupling. Both aliphatic and aromatic aldehydes were transformed into the decarboxylative A3-coupling products.