Determination of the Enantiomeric Excesses of Chiral Acids by 19F NMR Studies of their Esters deriving from (R)-(+)-2-(Trifluoromethyl)benzhydrol

Article abstract of DOI:10.1016/0957-4166(94)80154-1

15-Chiral acids were esterified with optically pure (R)-(+)-2-(trifluoromethyl)benzhydrol (R)-(+)-1, a readily available reagent.With respect to the carboxy group, the stereogenic centre is in the β-position in the case of the acids 5a-10a and 12a-16a, and in the α position in the case of the acids 17a-20a.The diastereomeric excesses of the corresponding esters 5b-10b and 12b-20b, respectively, were easily determined by means of 19F NMR.These d.e. values were in very good agreement with the e.e. values of the corresponding acids when the latter were known compounds.