Reductive dehalogenation of β-haloacrylic ester derivatives mediated by ene-reductases

The enzymatic bioreduction of β-halo-α,β-unsaturated carboxylic esters proceeded via sequential enzymatic CC reduction—β-elimination to afford saturated carboxylic esters. This novel biodegradation pathway combines the reductive activity of ene-reductases with the spontaneous β-elimination of hydrohalous acid from the unstable (saturated) intermediates. Both enantiomers of methyl 2-chloro-, 2-bromo- and 2-iodopropionate were obtained in good to excellent enantiopurity via enzyme-based stereocontrol using various members of the ‘Old Yellow Enzyme’ family of flavoproteins. Overall, this pathway resembles a reductive dehalogenation of β-halogenated acrylic esters.