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

The combination of a biocatalytic asymmetric C=C reduction with a simple sequence of chemical transformations was implemented in a new chemoenzymatic synthesis of various substituted aryloxyalkanoic acids, used as weed-killing agrochemicals or chiral precursors. By careful selection of the biocatalyst, either enantiomer of the product could be obtained in good yield and moderate to good ee. The method relies on the use of simple and commercially available starting materials, and requires neither purified enzymes nor chromatographic separations.