Photoredox Cleavage of a Csp3-Csp3 Bond in Aromatic Hydrocarbons.

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 Csp3-Csp3 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 Csp3-Csp3 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 Csp3-Csp3 bonds in molecules without any heteroatoms, resulting in primary, secondary, tertiary, and benzylic radical species.