UC Riverside

The versatility of Ni-catalyzed reactions enables a wide range of bond-forming methods but also complicates mechanistic understanding, as numerous pathways can lead to product formation. This thesis describes mechanistic investigations of two distinct Ni-catalyzed systems: photochemical Ni-catalyzed THF arylation and Ni-catalyzed cross-electrophile coupling of aryl iodides with benzyl chlorides. The approaches used to interrogate these systems rely on leveraging enantioselectivity data to determine the operative pathways under standard catalytic conditions. This work focuses on identifying the enantioselectivity-determining steps in these reactions to elucidate key catalytic intermediates. This strategy is broadly applicable across a variety of catalytic systems and reaction conditions, providing a general framework for gaining deeper mechanistic insight into transition metal-catalyzed reactions.The first approach involves conducting time-point experiments throughout a reaction and monitoring trends in product enantioselectivity over time. The second approach involves performing stoichiometric experiments with Ni species proposed to participate in the enantioselectivity-determining step, followed by comparison of the product ee obtained under stoichiometric conditions with that observed under catalytic conditions.To perform stoichiometric experiments that generate enantioenriched products, the Ni-complex must contain a chiral ligand. Despite the utility of chiral ligand scaffolds in asymmetric catalysis, examples of well-defined Ni-complexes bearing these ligands remain comparatively limited relative to their achiral counterparts. To address this gap, a general procedure was developed for the synthesis of Ni-complexes bearing bisoxazoline (BOX) and bioxazoline (BiOX) ligands that accommodates the structural diversity of these scaffolds. Our hope is that applying these studies to two different, difficult-to-investigate scenarios may serve as a roadmap for others investigating complex mechanistic scenarios.