Enantioselective chemoenzymatic synthesis of the S-enantiomer of the systemic fungicide fenpropimorph

Article abstract of DOI:10.1055/s-1995-4107

Chemoenzymatic synthesis of the S-(-)-enantiomer of fenpropimorph (S)-1 in high optical and chemical purity is described. One feature of this process entails the enantioselective acetylation of prochiral 1,3-propanediol 4 by Pseudomonas sp. lipases, and subsequent transformation of the monoacetate (R)-5 into the final product by the selected order of transformations that comprise; chlorination or tosylation under non-racemizing conditions, hydrogenolysis of the resulting chloromethyl or tosyl group in (+)-6 and (+)-8, second chlorination of (-)-9, and alkylation of cis-3,5-dimethylmorpholine by 1-chloropropane derivative (+)-10. This sequence of reactions affords (S)-1, the more active enantiomer in the commercialized racemic mixture with systemic fungicidal activity.