Coupling of Imines and Alkynes through Amino Acid and Metal Catalysis

Significance

Brønsted acid catalysts have received considerable attention in recent years (see Review below). While chiral phosphoric acid catalysts have been employed in metal-catalyzed reactions, simple amino acids received less attention. Herein, amino acids are utilized along with achiral copper-phosphine catalysts to give a highly tunable catalyst system for a coupling reaction. While the yields and enantiomeric ratios are good, the presented catalytic system is significant for its modularity, making it easy to be tuned by changing inexpensive and commercially available components. Proline was found to be the optimal amino acid in the reported transformation.