Atroposelective Synthesis of Planar‐Chiral Indoles via Carbene Catalyzed Macrocyclization

Abstract

AbstractIndole‐based planar‐chiral macrocycles are widely found in natural products and bioactive molecules. However, in sharp contrast to the preparation of indole‐based axially chiral structures, the enantioselective catalysis of indole‐based planar‐chiral macrocycles is still a formidable task so far. Here we report an N‐heterocyclic carbene (NHC)‐catalyzed intramolecular atroposelective macrocyclization of 3‐carboxaldehyde indole/pyrroles, featuring with broad substrate scope and good functional group tolerance, and allowing for a rapid access to diverse indole/pyrrole‐based planar‐chiral macrocycles with various tether‐lengths (10–16 members) in good yields and with excellent enantioselectivities. Importantly, the indole‐based macrocyclic structures with both planar and axial chirality were directly and efficiently obtained through this protocol with excellent enantioselectivities and diastereoselectivities. In addition, these synthesized planar‐chiral macrocycles offer many possibilities for chemists to develop new catalysts or ligands, as well as new reactions.