Photoredox Cleavage of a C<sub>sp3</sub>–C<sub>sp3</sub> Bond in Aromatic Hydrocarbons
Ke Liao, Cho Ying Chan, Siqi Liu, Xinhao Zhang, Jiean Chen, Yong Huang
Abstract
Functionalizing molecules through the selective cleavage of carbon–carbon bonds is an attractive approach in synthetic chemistry. Despite recent advances in both transition-metal catalysis and radical chemistry, the selective cleavage of inert C sp3 –C sp3 bonds in hydrocarbon feedstocks remains challenging. Examples reported in the literature typically involve substrates containing redox functional groups or highly strained molecules. In this article, we present a straightforward protocol for the cleavage and functionalization of C sp3 –C sp3 bonds in alkylbenzenes using photoredox catalysis. Our method employs two distinct bond scission pathways. For substrates with tertiary benzylic substituents, a carbocation-coupled electron transfer mechanism is prevalent. For substrates with primary or secondary benzylic substituents, a triple single-electron oxidation cascade is applicable. Our strategy offers a practical means of cleaving inert C sp3 –C sp3 bonds in molecules without any heteroatoms, resulting in primary, secondary, tertiary, and benzylic radical species.