Privileged Chiral Spiro Catalysts for Asymmetric Catalysis
Chiral catalysts play a crucial role in transition-metal-catalyzed asymmetric reactions, and many effective chiral catalysts have been synthesized over the past few decades. S ince there are no universal catalysts for asymmetric transformations and the enantioselectivity is substrate-dependent in most asymmetric reactions, the search for efficient chiral catalysts in terms of high enantioselectivity and high activity remains one of the most important tasks in asymmetric catalysis. We developed a number of chiral ligands having a chiral spirobiindane framework. The ruthenium, iridium, copper, and iron complexes of chiral sipro ligands showed high efficiency and enantioselectivity for various asymmetric reactions including asymmetric hydrogenation, asymmetric metal carbine insertion, and carbon-carbon formation reaction. The synthesis, structures, reactivity and enantioselectivity of the chiral spiro catalysts will be discussed in the presentation.