Chiral counteranion-directed silver-catalyzed asymmetric synthesis of 1,2-dihydroisoquinolines by Friedel-Crafts alkylation reactions

The reaction of ortho-alkynylaryl aldimines and indoles catalyzed by a silver binol-derived phosphate was realized to afford a series of enantioenriched 1,2-dihydroisoquinolines in moderate to good yields and ee. An interesting phenomenon that highly enantioenriched products could be obtained from their lower ee form by silica gel column chromatography was observed, providing an easy access to the enantiopure form of the product.