(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 1 H NMR spectra. Two computational methods were found to give the good predictions of distribution of the configurational and conformational isomers in the three solvents.