Catalytic Asymmetric Synthesis of Axially Chiral 3,3'‐Bisindoles by Direct Coupling of Indole Rings

TLDR: In this article , a new enantioselective synthesis strategy for axially chiral 3,3'-bisindoles was devised by the direct coupling of two indole rings.

Abstract: A new strategy for the enantioselective synthesis of axially chiral 3,3'-bisindoles was devised by the direct coupling of two indole rings. This strategy makes use of the C3-umpolung reactivity of 2-indolylmethanols, which enables the catalytic asymmetric addition reaction of 2-indolylmethanols with rationally designed 2-substituted indoles, thus constructing axially chiral 3,3'-bisindole scaffolds in overall excellent yields (up to 98%) with high enantioselectivities (up to 96 : 4 er). This approach not only has overcome the challenges in constructing axially chiral five-five-membered heterobiaryls, but also represents a new application of the C3-umpolung reactivity of 2-indolylmethanols in asymmetric catalysis. More importantly, this class of axially chiral 3,3'-bisindoles can undergo a variety of post-functionalizations to give axially chiral 3,3'-bisindole-based organocatalysts, which have found their preliminary applications in asymmetric catalysis. Appendix S1: Supporting Information Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.