Pd-Catalyzed α-Arylation of Sulfones in a Three-Component Synthesis of 3-[2-(Phenyl/methylsulfonyl)ethyl]indoles

A novel four-step domino process for the synthesis of 3-[2-(aryl/alkylsulfonyl)ethyl]indoles starting from readily available 2-iodoanilines is reported. The domino reaction is based on the intramolecular palladium-catalyzed alpha-arylation of sulfones, which was combined with both intermolecular aza-Michael and Michael addition reactions using vinyl sulfones as the electrophile. The domino process produced good yields and tolerated the presence of substituents with different electronic properties on the aniline ring. In addition, density functional theory (DFT) calculations were carried out to gain more insight into the formation of the observed indole derivatives.