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Unspecific Peroxygenases (UPOs) are increasingly significant enzymes for selective oxygenations as they are stable, highly active and catalyze their reactions at the expense of only hydrogen peroxide as the oxidant. Their structural similarity to chloroperoxidase (CPO) means that UPOs can also catalyze halogenation reactions based upon the generation of hypohalous acids from halide and H2O2. Here we show that the halogenation and oxygenation modes of a UPO can be stimulated at different pH values. Using simple aromatic compounds such as thymol, we show that, at a pH of 3.0 and 6.0, either brominated or oxygenated products respectively are produced. Preparative 100 mg scale transformations of substrates were performed with 60–72 % isolated yields of brominated products obtained. A one‐pot bromination‐oxygenation cascade reaction on 4‐ethylanisole, in which the pH was adjusted from 3.0 to 6.0 at the halfway stage, yielded sequentially brominated and oxygenated products 1‐(3‐bromo‐4‐methoxyphenyl)ethyl alcohol and 3‐bromo‐4‐methoxy acetophenone with 82 % combined conversion. These results identify UPOs as an unusual example of a biocatalyst that is tunable for entirely different chemical reactions, dependent upon the reaction conditions. [ABSTRACT FROM AUTHOR]

Controlling the selectivity of a chemical reaction with external stimuli is common in thermal processes, but rare in visible‐light photocatalysis. Here we show that the redox potential of a carbon nitride photocatalyst (CN‐OA‐m) can be tuned by changing the irradiation wavelength to generate electron holes with different oxidation potentials. This tuning was the key to realizing photo‐chemo‐enzymatic cascades that give either the (S)‐ or the (R)‐enantiomer of phenylethanol. In combination with an unspecific peroxygenase from Agrocybe aegerita, green light irradiation of CN‐OA‐m led to the enantioselective hydroxylation of ethylbenzene to (R)‐1‐phenylethanol (99 % ee). In contrast, blue light irradiation triggered the photocatalytic oxidation of ethylbenzene to acetophenone, which in turn was enantioselectively reduced with an alcohol dehydrogenase from Rhodococcus ruber to form (S)‐1‐phenylethanol (93 % ee). [ABSTRACT FROM AUTHOR]