Introducing Azaindole Thianthrenium Salt: An Electrophilic Coupling Partner for Cross-Coupling Reaction.

Herein, we report a new approach for the C3-H functionalization of azaindoles through thianthrenium salt formation. This versatile azaindole thianthrenium salt intermediate participates in a range of cross-coupling reactions, including Suzuki, Heck, Sonogashira, Hiyama, and Barluenga-Valdés-type coupling. By combining the site-selectivity of thianthrenation with the robustness of these electrophilic reagents, this protocol grants access to a large variety of azaindole derivatives that are otherwise challenging to prepare with comparable levels of selectivity, diversity, and practicality.