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

Abstract

Herein, we report a highly efficient Sonogashira-type crosscoupling reaction of heteroaryl halides with terminal alkynes under mild transition-metal-free conditions using PPh 3 and Cs 2 CO 3 /NEt 3 , 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.