Organocatalytic Asymmetric Cascade Bicyclization of 2‐Indolylmethanols with α‐(2‐Indolyl) Propargylic Alcohols to Access Chiral Fluorescent Hexacyclic Bisindoles

Abstract

A cascade regioselective 1,8‐addition/ biscyclization of 2‐indolylmethanols with α‐(2‐indolyl) propargylic alcohols has been developed via chiral phosphoric acid (CPA) catalysis. A series of chiral cyclopenta[4,5]pyrrolo biindoles bearing a quaternary stereogenic center were obtained in modest to good yields (72‐95%) with high enantioselectivities (82‐94%). Additionally, the photophysical properties of these hexacyclic bisindoles are examined, revealing bright fluorescence with high quantum yields.