Bifunctional Photocatalysts for Enantioselective Aerobic Oxidation of β‑Ketoesters

A novel
visible-light-responsive chiral ligand has been developed
by grafting a triplet state photosensitizer to chiral bisoxazoline
ligands. Complexation of this ligand with Ni­(acac)2 results
in a powerful catalyst for the asymmetric oxidation reaction of β-ketoesters,
which uses oxygen or air as the green oxidant and visible light or
sunlight as the ideal driving force. Using this protocol, products
containing the α-hydroxy-β-dicarbonyl motif are produced
in high yields and with excellent enantiopurities.