Organocatalytic Enantioselective Synthesis of 6‐Aryl‐5,6‐dihydrophenanthridines by a Modified Pictet–Spengler Reaction of Biphenyl‐2‐amines and Aromatic Aldehydes

Abstract

A straightforward approach to the enantioselective synthesis of chiral 5,6‐dihydrophenanthridines was developed. A series of chiral 6‐aryl‐5,6‐dihydrophenanthridines were obtained through an organocatalytically modified Pictet–Spengler reaction of biphenyl‐2‐amines and aromatic aldehydes. In the reaction, H8‐BINOL‐derived chiral imidodiphosphoric acid exhibited strong stereocontrolling and catalytic activities to afford the desired 6‐aryl‐5,6‐dihydrophenanthridines in high yields (up to 98 %) with high enantioselectivities (up to 99 % ee).