NHC‐Ag/Pd‐Catalyzed Reductive Carboxylation of Terminal Alkynes with CO₂ and H₂: A Combined Experimental and Computational Study for Fine‐Tuned Selectivity

Reductive carboxylation of terminal alkynes utilizing CO 2 and H 2 as reactants is an interesting and challenging transformation. Theoretical calculations indicated it would be kinetically possible to obtain cinnamic acid, the reductive carboxylation product, from phenylacetylene in a CO 2 /H 2 system with an N‐heterocyclic carbene (NHC)‐supported Ag/Pd bimetallic catalysts through competitive carboxylation/hydrogenation cascade reactions in one step. These calculations were verified experimentally with a poly‐NHC‐supported Ag/Pd catalyst. By tuning the catalyst composition and reaction temperature, phenylacetylene was selectively converted to cinnamic acid, hydrocinnamic acid, or phenylpropiolic acid in excellent yields.