Organocatalytic Enantioselective Conia‐Ene‐Type Carbocyclization of Ynamide Cyclohexanones: Regiodivergent Synthesis of Morphans and Normorphans

Abstract

Abstract Described herein is an organocatalytic enantioselective desymmetrizing cycloisomerization of arylsulfonyl‐protected ynamide cyclohexanones, representing the first metal‐free asymmetric Conia‐ene‐type carbocyclization. This method allows the highly efficient and atom‐economical construction of a range of valuable morphans with wide substrate scope and excellent enantioselectivity (up to 97 % ee ). In addition, such a cycloisomerization of alkylsulfonyl‐protected ynamide cyclohexanones can lead to the divergent synthesis of normorphans as the main products with high enantioselectivity (up to 90 % ee ). Moreover, theoretical calculations are employed to elucidate the origins of regioselectivity and enantioselectivity.