NMR-STUDIES OF AGRICULTURAL COMPOUNDS - APPLICATIONS OF ACHIRAL AND CHIRAL LANTHANIDE SHIFT-REAGENTS TO THE HERBICIDE, FENOXAPROP-ETHYL

The 200 MHz H-1 NMR spectra of the herbicide, fenoxaprop-ethyl, I, hav e been studied in CDCl3 solution at ambient temperatures as the racemi c ester free base with the added chiral lanthanide shift reagent (LSR) , tris[3- heptafluoropropylhydroxymethylene)-(+)-camphorato] europium( III), Eu (HFC)(3), 2, with some additional runs using the achiral LSR, tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,-5- octanedionato) euro pium(III), Eu (FOD)3, 3, for supplemental spectral simplification. Wit h 2, definite enantiomeric shift differences (Delta Delta delta) were observed only for the CH3CH2O resonance. Although increased spectral c omplexity for the CH2O signal was seen with added 2 this could have re sulted from anisochrony of the diastereotopic protons, H-a and H-b, of this methylene group rather than true Delta Delta delta, since the ac hiral 3 led to near-baseline separation between the CHaHbO signals. La nthanide-induced shift (LIS) magnitudes were interpreted as consistent with predominant LSR binding at the ester carbonyl.