Transition-Metal-Free Coupling Reactions: PPh3-Promoted Sonogashira-Type Cross-Couplings of Heteroaryl Halides with Terminal Alkynes

Herein, we report a highly efficient Sonogashira-type cross-coupling reaction of heteroaryl halides with terminal alkynes under mild transition-metal-free conditions using PPh3 and Cs2CO3/NEt3, A wide range of functional groups was tolerated under optimized conditions. Furthermore, the protocol could be extended to the Suzuki-type cross-coupling of heteroaryl halides with phenylboronic acid, achieving the corresponding products in good to excellent yields. A test reaction on gram scale delivered the product in reasonably high yield and thus has the potential of promising applications in drug discovery and functional materials.