(2013), 24, 1001-1009
Optically active 1-fluoroindan-1-carboxylic acid (FICA) was designed and prepd. as its Me ester for detg. the abs. configuration of chiral mols. by both 1H and 19F NMR spectroscopies. Enantiomerically pure isomers of FICA Me esters (FICA Me esters) were obtained by chromatog. sepn. using HPLC with a Daicel Chiralcel OJ-H column. The abs. configuration of the (+)-FICA Me ester was deduced to be (S) by X-ray crystallog. anal. of the (+)-FICA amide of (R)-α-phenethylamine. Both enantiomers were derived to the diastereomeric esters of chiral secondary alcs. by an ester exchange reaction. In the 1H NMR spectra, the signs of ΔδH(δR - δS) were consistent on each side of the FICA mol. plane. Therefore, the concept of the modified Mosher's method could be successfully applied to the FICA-based procedure. Moreover, the consistency in the signs of ΔδF(δR - δS) values suggests that the FICA method would be reliable in assigning the abs. configurations of secondary alcs. based on 19F NMR spectroscopy.
