Buchwald ligands and complexes play an important role in organometallic chemistry, especially in catalytic reactions. They are widely used in cross-coupling reactions (such as Heck reaction, Suzuki reaction, etc.). These ligands and complexes were studied and developed by chemist Stephen L. Buchwald and his colleagues, and are mainly used to improve the activity, selectivity and stability of transition metal catalysts (especially palladium catalysts). Buchwald ligands and complexes enable palladium-catalyzed reactions to proceed with higher efficiency and selectivity by optimizing the structure, electronic properties and stability of the catalyst. They are widely used in cross-coupling, nitrogen coupling, addition, redox and other reactions, especially in pharmaceuticals, material synthesis and fine chemical production, playing an irreplaceable and important role.