Dual Nickel/Photoredox-Catalyzed\nAryl Etherification\nEnabled by an Oxidative Near-Infrared-to-Blue Triplet–Triplet\nAnnihilation Upconversion System Leveraging Spin-Forbidden Excitation

Herein\nwe describe a near-infrared-to-blue triplet–triplet\nannihilation upconversion system that produces a highly oxidizing\nexcited state. The spin-forbidden excitation of the osmium sensitizer\nand thermally assisted triplet energy transfer to the anthracene annihilator\nenable an anti-Stokes shift of 1.25 V. This system is then applied\nto the dual nickel/photoredox-catalyzed cross-coupling of aryl halides\nand alcohols. Finally, we implicate upconversion as the promoter for\nreductive elimination of a nickel(II) aryl alkoxide complex.