Chiral Acid-Catalyzed Atroposelective Indolization Enables Access to 1,1′-Indole-Pyrroles and Bisindoles Bearing a Chiral N–N Axis

We present herein a highly atroposelective indolization for the efficient synthesis of 1,1′-biheteroaryls bearing a chiral N–N axis. Under the cooperative catalysis of chiral phosphoric acid and InBr 3, the reactions between 2,3-diketoesters and 1,3-dione-derived enamines resulted in a highly enantioselective construction of 1,1′-pyrrole-indoles with up to 92% yield, 94% enantiomeric excess (ee), or bisindoles in up to 92% ee. Derivatizations of these compounds to diverse functionalized N–N linked axially chiral biheteroaryls have also been demonstrated.