Study of solvents effect on distribution of configurational and conformational isomers of apo-tirucallol theoretically and experimentally

(2S,3R)-2-(2-Hydroxypropan-2-yl)-5-methyltetrahydro-2H-pyran-2,3-diol and its configurational isomer (2R,3R)-2-(2-hydroxypropan-2-yl)-5-methyltetrahydro-2H-pyran-2,3-diol were used in the distribution analyses of configurational and conformational isomers for the identification of 1α,7α-diacetoxyl-17α-20S-21,24-epoxy-apo-tirucall-14-ene-3α,23R,24S,25-tetraol in methanol, chloroform and acetone solvents, respectively. The geometries of configurational and the corresponding conformational isomers were optimized through B3LYP/6-31G(d) and MP2/6-311+G(d) tests in the gas phase and in the three solvents, respectively. PCM and CPCM models were used, respectively. Distributions of different isomers in the three solvents were finally examined by 1H NMR spectra. Two computational methods were found to give the good predictions of distribution of the configurational and conformational isomers in the three solvents.