iScience (Feb 2020)
Enantioselective [4+2] Annulation to the Concise Synthesis of Chiral Dihydrocarbazoles
Abstract
Summary: A highly efficient phosphine-catalyzed enantioselective [4 + 2] annulation of allenoates with 3-nitroindoles or 3-nitrobenzothiophenes has been developed. The protocol represents a unique dearomatization–aromatization process to access functionalized dihydrocarbazoles or dihydrodibenzothiophenes with high optical purity (up to 97% ee) under mild reaction conditions. The synthetic utility of the highly enantioselective [4 + 2] annulation enables a concise synthesis of analgesic agent. : Catalysis; Organic Synthesis; Organic Reaction Subject Areas: Catalysis, Organic Synthesis, Organic Reaction