Ligand-Controlled Chemodivergent Bismuth Catalysis

Herein, we report a ligand-controlled chemodivergent bismuth-catalyzed coupling between arylboronic acids and N-fluorosulfonimide derivatives that enables the selective formation of either C(sp²)-N or C(sp²)-O bonds. Selectivity is achieved by the modulation of the electronic and steric properties of a common ligand framework for bismuth, thus establishing an unusual ligand-controlled chemodivergent platform in main group catalysis. Specifically, the use of an electron-enrich sulfone ligand led to the major formation of sulfonimide with selectivities ranging from 2:1 to more than 20:1. Conversely, a bismuth catalyst supported by an electron-deficient sulfoximine predominantly promoted the sulfonimidate product with ratios ranging between 5:1 and 15:1. To understand the underlying principles that control the selectivity, a comprehensive mechanistic investigation was conducted by combining experimental stoichiometric studies, DFT calculations, and statistical modeling. These studies support a catalytic high-valent bismuth redox cycle, where Bi(V) intermediates dictate product selectivity through either a three- or five-membered reductive elimination-ligand coupling event. By means of statistical modeling, we identified that the charge of the coordinating heteroatom through hypervalency, together with a steric parameter around the bismuth, is the key parameter responsible for the stabilization of the relevant transition states that lead to control over the reductive elimination process.