Switching between enantiomers by combining chromoselective photocatalysis and biocatalysis - Schmermund, Luca; Reischauer, Susanne; Bierbaumer, Sarah; Winkler, Christoph; Diaz-Rodriguez, Alba; Edwards, Lee J.; Kara, Selin; Mielke, Tamara; Cartwright, Jared; Grogan, Gideon; Pieber, Bartholomäus; Kroutil, Wolfgang (ChemRxiv, 2021)
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).
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Keywords: preprint