Asymmetric Aza Friedel–Crafts\nReaction of 3,4-Dihydroisoquinolines\nwith 1‑Naphthols Catalyzed by Chiral Phosphoric Acids

An\nefficient chiral phosphoric acid-catalyzed asymmetric aza Friedel–Crafts\nreaction of 3,4-dihydroisoquinolines and 1-naphthols is described.\nThe reaction provides a general method for the synthesis of diverse\nchiral tetrahydroisoquinoline with 1-naphthol substituents at the\nC1-position in excellent yields and enantioselectivities. Based on\nthe conducted mechanistic experiments, a plausible catalytic mechanism\nwas proposed. Moreover, the practicability of the reaction is successfully\ndemonstrated by its application on a gram scale.