Chiral Phosphoric Acid-Catalyzed Asymmetric Cascade Reactions Of3-Substituted Indoles:Construction Of Chiral Polycyclic Indoles

2,3-dihydro-1H-pyrrolo [1,2-a] indoles are common structural subunits in many natural alkaloids and pharmacological agents. Many of them are biological activity and also serve as versatile building blocks in organic synthesis. For example, Isoborreverine and Finderoles have antimalarial activity, JIT-010can lower blood sugar. The synthesis of these chemical skeleton, especially chiral skeleton, are the focus of research interests in the area of organic synthesis. Nowadays, many methods currently developed chemical synthesis that advantage structural skeleton provides new methods and approaches, In this paper, we found asymmetric cascade reactions of β,γ-unsaturated a-iminoesters and3-substituted indoles to construct2,3-dihydro-lH-pyrrolo[1,2-a]indoles. The details are as follows.Based on the nucleophilic ability of the Nl and C2position of indoles, an organic-catalyzed enantioselective Friedel-Crafts alkylation/N-hemiacetalization cascade of substituted indoles with β,γ-unsaturated a-iminoesters has been reported. This mild strategy provides a new access to various synthetically and biologically important2,3-dihydro-lH-pyrrolo [1,2-a]indoles in a good enantioselective manner.