Chemoenzymatic Synthesis of Enantioenriched (R)- and (S)- Aryloxyalkanoic Herbicides

The combination of a biocatalytic asymmetric C=C reductionwith a simple sequence of chemical transformations wasimplemented in a new chemoenzymatic synthesis of varioussubstituted aryloxyalkanoic acids, used as weed-killing agrochemicals or chiral precursors. By careful selection of thebiocatalyst, either enantiomer of the product could be obtainedin good yield and moderate to good ee. The method relies onthe use of simple and commercially available starting materials,and requires neither purified enzymes nor chromatographicseparations.