Light-Driven Cobalt Hydride Catalyzed Hydroarylation of Styrenes

We report a conceptually distinct strategy for the synthesis of 1,1-diarylalkanes and triarylalkanes. Key to this approach is the use of light to simultaneously trigger (i) formation of a CoIII–H species which undergoes H atom transfer (MHAT) to styrenes, giving a carbon-centered radical, and (ii) generation of a persistent (hetero)arene radical. Selective coupling of these two species yields Markovnikov hydroarylation products under mild conditions and without precious metals. In contrast to many previous approaches, electron-deficient (hetero)arene coupling partners are favored and it is possible to construct highly congested quaternary centers, including those with three different aryl groups.