We describe a photocatalytic system that elicits potent photoreductant activity from conventional photocatalysts by leveraging radical anion intermediates generated <i>in situ</i>. The combination of isophthalonitrile and sodium formate promotes diverse aryl radical coupling reactions from abundant but difficult to reduce aryl chloride substrates. Mechanistic studies reveal two parallel pathways for substrate reduction both enabled by a key terminal reductant byproduct, carbon dioxide radical anion.

We describe a photocatalytic system that elicits potent photoreductant activity from conventional photocatalysts by leveraging radical anion intermediates generated <i>in situ</i>. The combination of isophthalonitrile and sodium formate promotes diverse aryl radical coupling reactions from abundant but difficult to reduce aryl chloride substrates. Mechanistic studies reveal two parallel pathways for substrate reduction both enabled by a key terminal reductant byproduct, carbon dioxide radical anion.

<div> <div> <div> <p>Herein, we leverage electrochemistry to examine the photocatalytic activity of a range of structurally diverse persistent radical anions and find that many are effective electrophotocatalysts. These studies uncover a new electron-primed photoredox catalyst capable of promoting the reductive cleavage of strong C(sp2)–N and C(sp2)–O bonds even when reduction potentials hundreds of mV more negative than Li0 are required. We illustrated several examples of the synthetic utility of these deeply reducing but otherwise safe and mild catalytic conditions. Finally, we employed electrochemical current measurements to perform a reaction progress kinetic analysis that revealed that the improved activity of this new catalyst was a consequence of an enhanced stability profile. </p> </div> </div> </div>