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Bismuth redox catalysis
Presented by Dr. Josep Cornella
Hosted by Prof. Rovis
The ability of the main group element bismuth (Bi) to maneuver between different oxidation states in a catalytic redox cycle will be presented. We will show how Bi mimics the canonical organometallic steps of a transition metal, thus challenging the current dogmas of redox catalysis. A series of Bi complexes capable of revolving between oxidation states Bi(I)/Bi(III) and Bi(III)/Bi(V) have been unlocked and applied in various contexts of catalysis for organic synthesis. For example, capitalizing on the Bi(III)/Bi(V) redox pair, we have developed a catalytic protocol for the C‒F and C‒OTf bond formation from aryl boronic esters. On the other hand, a low-valent redox manifold based on Bi(I)/Bi(III) enabled the reduction of hydrazines and nitro compounds, the catalytic decomposition of the rather inert nitrous oxide (N2O), the catalytic hydrodefluorination of C(sp2)‒F bonds. In addition, we will show how one-electron pathways are also accessible, thus providing a platform for SET processes capitalizing on the triad Bi(I)/Bi(II)/Bi(III) for organic synthesis. Finally, we will also show how redox-neutral catalytic pathways can unlock novel organic transformations via canonical organometallic steps. For all methodologies, a combination of rational ligand design with an in depth analysis of all the catalytic steps proved crucial to unfold the catalytic properties of such an intriguing element of the periodic table..
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