AN EFFICIENT CHEMOENZYMATIC SYNTHESIS OF S-(-)-FENPROPIMORPH

First enantioselective synthesis of phenyl)-2-methyl]propyl-cis-3,5-di methylmorpholine (6), biologically active enantiomer of the systematic fungicide fenpropimorph, is reported. It comprises reacting 4-tert-bu tylbenzylbromide with methyldiethylmalonate, decarbethoxylation of 2 i nto racemic 3-(4-tert-butylphenyl)-2-methylpropionic acid ethylester ( 3) in DMSO in the presence of alkali, then Pseudomonas sp. lipase cata lyzed kinetic resolution of racemic 3 into S-(+)-acid (4), base-cataly zed racemization and recycling of the R-(-)-ester 3, acylation of cis- 3,5-dimethylmorpholine, and final reduction of the intermediary amide 5 to provide enantiomerically pure S-(-)-6.