N-Heterocyclic carbene/photo-cocatalyzed oxidative Smiles rearrangement: synthesis of aryl salicylates from O-aryl salicylaldehydes

The N-heterocyclic carbene/photo-cocatalyzed oxidative Smiles rearrangement of O-aryl salicylaldehydes was developed. Both electron-deficient and electron-rich aryls worked well as migrating groups, giving the corresponding aryl salicylates in good yields. This reaction features formation of two new C-O bonds and one C-O bond cleavage via metal-free oxidation of the Breslow intermediate using oxygen as the terminal oxidant and following the Smiles rearrangement under photocatalysis.