Highly Enantioselective Pictet–Spengler Reaction Catalyzed by SPINOL‐Phosphoric Acids

Chiral SPINOL-phosphoric acids are highly enantioselective catalysts for the asymmetric Pictet–Spengler reaction of Nb-α-naphthylmethyl tryptamines with a series of aliphatic and aromatic aldehydes, affording optically active tetrahydro-β-carbolines in excellent yields and ee values. The current protocol has been applied in the asymmetric total synthesis of (−)-harmicine.