Fig. 7: Proposed reaction mechanism.

The iridium photocatalyst serves to reduce the N-acyllutidnium bound to the Ni(II) species (3IV), furnishing Ni(III) species 2V. 2V undergoes light-assisted C–H activation and reduction elimination to deliver the ketone product and Ni(I) species 2VII. Finally, 2VII is oxidized back the the initial catalyst 3I.