Molecular mechanics calculations and comparison of proton, fluorine, and carbon NMR diastereomer discrimination via nonbonding interactions between fluorine-labeled enantiomeric amides and enantiomerically pure chiral solvating agents

Abstract

Diastereomer discrimination of fluorine-labeled enantiomers in chloroform solutions was studied with and without two chiral solvating agents (1S and 2S) using 1 H, 13 C, and 19 F NMR spectroscopy. Although by 13 C NMR spectroscopy the diastereomer discrimination is not observable, changes of chemical shifts for some carbon atoms unambiguously show formation of nonbonding interactions between the enantiomers and the chiral solvating agents. The position and the ratio of signal sets in both hydrogen and fluorine NMR spectra correspond to the enantiomeric composition in the solution