Photoredox-Catalyzed Radical-Radical Coupling of Potassium Trifluoroborates with Acyl Azoliums

Potassium trifluoroborates have gained significant utility as coupling partners in organic synthesis, particularly in the Suzuki-Mi-yaura coupling reaction. Recently, they have also been used as radical precursors under oxidative conditions to generate carbon-centered rad-icals. These versatile reagents have found new applications in photore-dox catalysis, including radical substitution, conjugate-addition reac-tions, and transition-metal dual catalysis. In addition, this photomediated redox-neutral process has enabled radical-radical cou-pling with persistent radicals in the absence of a metal, and this process remains to be fully explored. In this study, we report the radical-radical coupling of potassium benzylic trifluoroborate salts with isolated acyl azolium triflates, which are persistent-radical precursors. The reaction is catalyzed by an organic photocatalyst and forms isolable tertiary alco-hol species. These products can be transformed into a range of substi-tuted ketone products by simple treatment with a mild base.

Automated summary

Potassium trifluoroborates have been widely used as coupling partners in organic synthesis, and also as radical precursors to generate carbon-centered radicals under oxidative conditions. These versatile reagents have found new applications in photoredox catalysis, including radical substitution, conjugate-addition reactions, and transition-metal dual catalysis. In addition, this photomediated redox-neutral process enables radical-radical coupling with persistent radicals in the absence of metals, which remains to be fully explored.