Mechanometallaphotoredox catalysis: utilizing increased throughput mechanochemistry to develop air-tolerant solvent-minimized metallaphotoredox dual catalysis reactions

Photocatalysis as a tool used in organic synthesis has predominantly relied on the use of solvents, be it under homogeneous or heterogeneous conditions. In particular, metallaphotoredox catalysis reactions typically use toxic organic solvents such as DMA and DMF. Herein, we demon-strate how mechanophotocatalysis, the synergistic union of mechanochemistry and photocatalysis, is compatible with this class of dual catalysis reactions involving both photocatalyst and nickel(II) co-catalysts. Using ball milling, these mechanistically complex reactions can be conducted in the ab-sence of bulk solvent and under air, affording high yielding aryl aminations and C(sp2)-C(sp3) cross-couplings. These advances are facilitated by the introduction of a novel reaction vessel design for conducting four mechanophotocatalysis reactions simultaneously. This works highlights the promise of solvent-minimized photocatalysis reactions, demonstrating that in these examples bulk solvent is redundant, thus significantly reducing this waste stream.