Chromoselective Photocatalysis Enables Stereocomplementary Biocatalytic Pathways.

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 ()- or the ()-enantiomer of phenylethanol. In combination with an unspecific peroxygenase from , green light irradiation of CN-OA-m led to the enantioselective hydroxylation of ethylbenzene to ()-1-phenylethanol (99 % ). In contrast, blue light irradiation triggered the photocatalytic oxidation of ethylbenzene to acetophenone, which in turn was enantioselectively reduced with an alcohol dehydrogenase from to form ()-1-phenylethanol (93 % ).