Photocatalytic Enantioselective Oxidation by Artificial Monooxygenases Using Molecular Oxygen as a Green Oxidant

We report an artificial monooxygenase system that drives enantioselective oxidation directly utilizing molecular oxygen under visible‐light irradiation. This biohybrid catalyst consists of noncatalytic protein and metal complexes, i.e., copper 4,4‐tetraaza‐29H,31H phthalocyanine (CuTPC) bound to bovine serum albumin (BSA) and then assembled onto a synthetic photocatalyst, graphitic carbon nitride (g‐C 3 N 4 ). The resulting hybrid system facilitates a photocatalytic reaction cascade to enable enantioselective oxidation using molecular oxygen as an oxidant: g‐C 3 N 4 reduces oxygen photocatalytically and produces H 2 O 2 , which subsequently activates CuTPC‐BSA to drive enantioselective oxidation reactions. Using styrene and propionic acid as model substrates, the photocatalytic system selectively produces R‐styrene oxide and L‐lactic acid, respectively, achieving enantiomeric excesses exceeding 99% under visible‐light irradiation. In contrast, g‐C 3 N 4 alone did not provide enantioselectivity. Thus, CuTPC‐BSA/g‐C 3 N 4 represents a promising and cost‐effective alternative to natural enzymes to produce chiral oxidation products in a much sustainable way.