ENANTIOSELECTIVE CHEMOENZYMATIC SYNTHESIS OF THE S-ENANTIOMER OF THE SYSTEMIC FUNGICIDE FENPROPIMORPH

Chemoenzymatic synthesis of the S-(-)-enantiomer of fenpropimorph (S)- 1 in high optical and chemical purity is described. One feature of thi s process entails the enantioselective acetylation of prochiral 1,3-pr opanediol 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 o r tosyl group in (+)-6 and (+)-8, second chlorination of(-)-9, and alk ylation of cis-3,5-dimethylmorpholine by 1-chloropropane derivative ()-10. This sequence of reactions affords (S)-1, the more active enanti omer in the commercialized racemic mixture with systemic fungicidal ac tivity.