Catalytic Asymmetric Friedel–Crafts Alkylation of Indole via In Situ Generated Indol‐2‐one

Abstract

AbstractAn asymmetric Friedel–Crafts alkylation of indole with in situ generated indol‐2‐one from functionalized 3‐bromooxinidole catalyzed by chiral N,N’‐dioxide/Ni(BF4)2 has been developed. This protocol provides an efficient route to stereoselective construction of a series of 3‐substituted 3’‐indolyloxindoles bearing a quaternary carbon center in excellent yields and enantioselectivities (up to 99 % ee). In addition, the conversion of the resulted 3‐substituted 3’‐indolyloxindole to the key intermediate for the formal synthesis of (+)‐folicanthine was also demonstrated.