Ruthenium(II)-Catalyzed Selective C–H Bond Activation of Biindoles and Coupling with Sulfoxonium: An Efficient Access to Pyrido[1,2- a :4,3- b ′]diindole frameworks.

This article presents a study on the synthesis of pyrido[1,2-a:4,3-b']diindoles through a ruthenium-catalyzed coupling/cyclization reaction. The researchers investigated the reaction conditions and found that electron-donating groups and certain substitutions on the indole ring were well tolerated, resulting in good yields of the desired products. The proposed reaction pathway involves the formation of a ruthenacycle intermediate, followed by the insertion of a sulfur ylide and subsequent cyclization. The authors suggest that these pyrido[1,2-a:4,3-b']diindole derivatives may have potential pharmaceutical applications. [Extracted from the article]