Palladium precatalysts containing meta-terarylphosphine ligands for expedient copper-free Sonogashira cross-coupling reactions

摘要

Three novel palladium complexes utilizing different variations of the evolutionary meta-terarylphosphine ligand, Cy*Phine, were developed. These air-and moisture-stable complexes, PdCl2L2 (L = Cy*Phine, Cy*Phine-CF3 and Cy*Phine-nBu), demonstrated exceptional broad-based performance and operational simplicity in the copper-free Sonogashira cross-coupling of challenging (hetero-) aryl chlorides and terminal alkynes. Modifications to the periphery of the ligand scaffold showed modest improvements in the reaction rate when more electron-donating substituents were incorporated, which hints at potential design upgrades in the future.