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Long-range shielding effects in the (1)H NMR spectra of Mosher-like ester derivatives
Thomas R Hoye1, Sara E Erickson, Sherrie L Erickson-Birkedahl
1Department of Chemistry, 207 Pleasant Street, SE, University of Minnesota, Minneapolis, Minnesota 55455, USA. hoye@umn.edu
Abstract:
The relative magnitudes of the chemical shift differences (Deltadeltas) in the two diastereomers of menthyl esters of known chiral derivatizing agents (CDAs) were compared to those of the alpha-methoxy-alpha-trifluoromethyl-1-naphthylacetyl (MTN((1))A) analogues I. Discrimination of the terminal diastereotopic methyl resonances in esters of the homologous, symmetrical carbinols II was evaluated. Remarkably, the methyls differed in the MTN((1))A esters III even when n = 15; an unexpected crossover in the sign of the Deltadelta values was also observed.
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