Hydrazone‐Type Ligands for Asymmetric Catalysis

This is the authors' abstract. We don't add key points for this paper.

Hydrazone‐based ligands have emerged as a versatile class of chiral ligands for asymmetric catalysis. Their structural modularity, tunable electronic properties, and diverse coordination modes make them attractive alternatives to more established N ‐based ligand families. This review summarizes the development of hydrazone ligands from the earliest C 2 ‐symmetric glyoxal bis‐hydrazones to more advanced phosphino hydrazone and pyridino hydrazone ligands specifically designed to improve catalytic activity, stereocontrol, and coordination versatility. The original glyoxal bis‐hydrazone systems established the viability of hydrazone ligands in Cu‐catalyzed Diels–Alder reactions and Pd‐catalyzed atroposelective cross‐coupling processes. Subsequent generations of ligands significantly expanded the scope of these catalytic platforms, particularly in Pd(II)‐catalyzed additions of arylboronic acids to enones, imines, and hydrazones, enabling efficient access to structurally diverse chiral building blocks. Moreover, the application of hydrazone ligands in Ni‐ and Ru‐catalyzed asymmetric transformations has further demonstrated their adaptability across distinct catalytic manifolds. Special emphasis is placed on the relationship between ligand design, coordination behavior, and catalytic performance, highlighting how subtle structural modifications within the hydrazone framework strongly influence reactivity and stereoselectivity. Collectively, these studies establish hydrazones as a distinctive and promising, yet underexplored platform for future developments in asymmetric catalysis.