Silver tungstate: a single-component bifunctional catalyst for carboxylation of terminal alkynes with CO₂ in ambient conditions

Silver tungstate was successfully developed as a bifunctional catalyst for the ligand-free carboxylation of various terminal alkynes with electron-withdrawing or electron-donating groups under atmospheric pressure of carbon dioxide (CO₂) at room temperature. In this protocol, dual activation – i.e., the terminal alkyne activated by silver, and CO₂ activation by the tungstate anion – was verified using nuclear magnetic resonance spectroscopy, and means that this reaction can be run under ambient conditions. Notably, this protocol can be applied to the preparation of a phenylacrylate derivative by a cascade reaction using phenylacetylene, CO₂ and benzylamine as starting materials.