Visible-Light Induced C(sp2)-H Amidation with an Aryl-Alkyl σ-Bond Relocation via Redox-Neutral Radical-Polar Crossover

We report an approach for the intramolecular C(sp(2))-H amidation of N-acyloxyamides under photoredox conditions to produce delta-benzolactams with an aryl-alkyl sigma-bond relocation. Computational studies on the designed reductive single electron transfer strategy led us to identify N-[3,5-bis(trifluoromethyl)benzoyl] group as the most effective amidyl radical precursor. Upon the formation of an azaspirocyclic radical intermediate by the selective ipso-addition with outcompeting an ortho-attack, radical-polar crossover was then rationalized to lead to the rearomative ring-expansion with preferential C-C bond migration.

Automated summary

In this study, an intramolecular C(sp(2))-H amidation of N-acyloxyamides under photoredox conditions was reported to produce delta-benzolactams with an aryl-alkyl sigma-bond relocation. Computational studies identified the N-[3,5-bis(trifluoromethyl)benzoyl] group as the most effective amidyl radical precursor, which led to the rationalization of radical-polar crossover for ring-expansion with C-C bond migration.