Dynamic Kinetic Resolution Approach to Chiral Sulfur‐Containing Aza‐[5]helicenes via Chiral Lewis Base Catalyzed C─H Sulfenylation

Abstract

A chiral sulfide‐catalyzed C─H sulfenylation reaction for the efficient synthesis of chiral sulfur‐containing aza‐[5]helicenes has been developed for the first time. The chiral 1,1′‐binaphthyl‐2,2′‐diamine (BINAM)‐derived sulfide, bearing a tert‐butyl group, was identified as the optimal catalyst. The transformation proceeds via a dynamic kinetic resolution (DKR) process, attributed to the low rotational energy barrier of the indole substrates. This approach features simple and mild reaction conditions, good functional group tolerance, and broad substrate scope (41 examples). A diverse range of chiral sulfur‐containing aza‐[5]helicenes were obtained in high to excellent yields with high to excellent enantioselectivities (up to 99% yield and 97% ee). Furthermore, this catalytic system demonstrates applicability for the modification of drug molecules and aggregation‐induced emission (AIE) molecules. Density functional theory (DFT) calculations reveal that π⋯π and C─H⋯π interactions play a critical role in determining the observed enantioselectivity.