Metal-Free, Visible-Light-Induced Selective C-C Bond Cleavage of Cycloalkanones with Molecular Oxygen.

A metal-free, visible-light-induced oxidative C-C bond cleavage of cycloketones with molecular oxygen is described. Cooperative Brønsted-acid catalysis and photocatalysis enabled selective C-C bond cleavage of cycloketones to generate an array of γ-, δ- and ϵ-keto esters under very mild conditions. Mechanistic studies indicate that singlet molecular oxygen (1 O2 ) is responsible for this transformation.