Asymmetric synthesis of dihydrocarbazoles through a Friedel–Crafts alkylation/annulation sequential reaction of indoles

Abstract

An enantioselective tandem Friedel–Crafts alkylation/annulation of indoles with diazoacetoacetate enones is realized in one pot. A series of dihydrocarbazoles were obtained in moderate yields with good to excellent ee values by using a Rh^II/Sc^III dual-metallic catalyst system. Control experiments revealed that Sc^III is critical to both the alkylation and annulation.