Harnessing the potential of acyl triazoles in bifunctional cobalt-catalyzed radical cross-coupling reactions

Abstract

Persistent radicals facilitate numerous selective radical coupling reactions. Here, we have identified acyl triazole as a new and versatile moiety for generating persistent radical intermediates through single-electron transfer processes. The efficient generation of these persistent radicals is facilitated by the formation of substrate-coordinated cobalt complexes, which subsequently engage in radical cross-coupling reactions. Remarkably, triazole-coordinated cobalt complexes exhibit metal-hydride hydrogen atom transfer (MHAT) capabilities with alkenes, enabling the efficient synthesis of diverse ketone products without the need for external ligands. By leveraging the persistent radical effect, this catalytic approach also allows for the development of other radical cross-coupling reactions with two representative radical precursors. The discovery of acyl triazoles as effective substrates for generating persistent radicals and as ligands for cobalt catalysis, combined with the bifunctional nature of the cobalt catalytic system, opens up new avenues for the design and development of efficient and sustainable organic transformations. Persistent radical-mediated cross-coupling has emerged as a powerful tool in organic synthesis for forging new C-C bonds. Here, the authors identify acyl triazoles as a versatile moiety for generating persistent radical intermediates through single-electron transfer processes, in the context of cobalt-catalysed carbon-carbon couplings under photoirradiation.