The described cascade reaction was scaled up to the preparative scale. For this purpose, 3.31 mL 1 M glucose solution, 3.31 mL 10 mM NADP + solution, 50 mg 12 (0.331 mmol), 103 µL 13 (40 % (w/w) in water), 1.25 mL acetonitrile and 36 mL 50 mM sodium phosphate buber pH 8.0 were added to a 200 mL Erlenmeyer flask. The pH was adjusted to 8.0 with 5 M HCl. Then 331 µL BmGDH (313 µM stock) and 6.62 mL IRED15 (400 µM stock) were added and incubated for 48 hours at 25 °C and 180 rpm (New Brunswick Innova42, Eppendorf SE, Hamburg, Germany). Time samples were taken after 4, 24 and 48 hours. After 48 hours, 15 mL of a 500 mM sodium phosphate buber containing 300 mM NaCl pH 8.0, 945 µL NfsA (700 µM stock) was added. Since no NR activity was observed after 2 hours, a further 200 µL of BmGDH was added to the reaction. Further time samples were taken 1, 2 and 20 hours after the addition of GDH before the reaction was worked up. For this purpose, the reaction mixture was extracted six times with 30 mL of methyl tert-butyl ether (MTBE). The combined organic phases were dried in the presence of silica and purified by medium-performance liquid chromatography (MPLC). The MPLC separation was performed using a Büchi MPLC system (C-815 Flash, Flawil, Switzerland) equipped with a Flashpure EcoFlex silica column (4 g, 50 µm irregular). The mobile phase consisted of n-heptane and MTBE. Gradient elution began with 5 % MTBE, which was maintained for 5 minutes, followed by a gradual increase in MTBE concentration to 50 % over 30 minutes. The flow rate was set to 20 mL/min. Detection was performed using a UV detector at 254 nm. The fractions containing the desired product were combined and dried with a rotary evaporator. 27 mg (0.205 mmol, 62 %) of product 6b was obtained as a colorless solid. The proton and carbon nuclear magnetic resonance ( 1 H-NMR and 13 C-NMR) analysis was performed in deuterated chloroform (CDCl3) using a 500 MHz NMR. The spectra were related to the solvent peak of CDCl3 and compared with spectra from literature.