From Mono‐Triazolium Salt to Bis‐Triazolium Salt: Improvement of the Asymmetric Intermolecular Benzoin Condensation

A solution to the long‐standing challenge of developing a highly effective method for the enantioselective intermolecular benzoin condensation of aromatic aldehydes is described. The chiral bis‐bicyclic triazolium salt – 1,3‐bis{( S )‐5‐benzyl‐6,8‐dihydro‐5 H ‐[1,4]oxazino[2,1‐ c ][1,2,4]triazol‐2‐ium‐2‐yl}benzene dichloride [( S )‐ 5a‐1 ] is currently the most efficient precatalyst for the asymmetric variant of the benzoin condensation.