Conf. G (kcal/mol) ΔG (kcal/mol) Pi% Dex-1 -1023249.80 0 79.8 Dex-2 -1023248.80 1.001 14.5 Dex-3 -1023248.26 1.542 5.7 Levo-1 -1023249.71 0 79.9 Levo-2 -1023248.67 1.039 13.6 Levo-3 -1023248.24 1.465 6.5 awhich related to the most stable conformer. bBoltzmann weighting factor (Pi%) based on ΔG.

Table 1: Gibbs free energies (G), relative Gibbs free energies (ΔG)a and Boltzmann weighting factor (P%)b of Dex and Levo conformers by using the DFT/B3LYP/6- 311++G(d,p) method.