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.