Computational Characterization of the Mechanism for Coinage-Metal-Catalyzed Carboxylation of Terminal Alkynes

Several experimentally reported copper-, silver-, and gold-catalyzed carboxylation processes of terminal alkynes are studied with DFT methods to find out the mechanism ruling these transformations. The computational results indicate that the reaction follows a very similar pathway for all three metals: the crucial step involves the electrophilic attack of an unactivated carbon dioxide unit on a metal-s-acetylide complex. The calculations lead to the proposal of additional silver and gold catalytic systems that could perform this reaction at mild temperatures.