ENANTIOCOMPLEMENTARY SYNTHESIS OF CHIRAL ALCOHOLS COMBINING PHOTOCATALYSIS AND WHOLE-CELL BIOCATALYSIS IN A ONE-POT CASCADE PROCESS

摘要

As a powerful tool in synthetic organic chemistry, photocatalysis has the features of green, better atom economy, and mild conditions. Recently, some cascade reaction protocols have been properly designed by combining photocatalysis and biocatalysis. For example, Zhao and Hartwig reported an asymmetric reaction which coupled photocatalysts for E/Z isomerization of alkenes with ene-reductases for the reduction of carbon-carbon double bonds, to generate valuable enantioenriched products , which achieved the dual-advantages of both photocatalysis and biocatalysis. We envisioned a photochemo-enzymatic one-pot whole-cell process to convert a series of carboxylic acids into corresponding chiral alcohols with good yields (up to 93%) and excellent stereoselectivity (up to 99% ee). The photocatalysis step was conducted in aqueous phase by using O_2 as oxidant and the following whole cell bioreduction without the addition of the expensive cofactor NADPH was a much milder and more efficient approach to obtain chiral alcohols. All these advantages indicate that the photochemo-enzymatic one-pot transformation may have great potential in green synthetic chemistry.