Accurate conformation analysis in solution: NMR and DFT/PCM study of the S-3-(1-naphthoyl)-4-isopropyl-2,2-dimethyloxazolidin-5-one in CDCl3

The title molecule has been synthesised and the low temperature NMR spectrum recorded in CDCl₃. The spectrum shows that four conformers lie within 0.08 eV at 210 K. We show that an accurate conformation analysis can be obtained with a full and consistent use of the DFT (B3LYP) and PCM methods. If the polarised Stuttgart-Dresden basis and a PCM cavity with individual spheres on the hydrogen atoms are used, if the thermal and PCM non-electrostatic contributions are taken into account, and if a demanding convergence is achieved, then the rms error on the energy differences amounts to 0.002 eV. The 6-31+g(d) basis is larger and yields a larger rms error: 0.006 eV.