The detailed results and comparison of the 13 C-NMR calculation and measurements are given in Table for validation purposes. The calculated chemical shifts are referenced to tetramethylsilane (TMS), for both carbon ( 13 C-NMR, δC = 182.66 ppm) and proton ( 1 H-NMR, δH = 31.88 ppm) spectra of the exo-chair isomer. It is important to recognize that different experimental conditions may introduce variations, often reflected as error bars in the reported data. For example, the two NMR measurements in the same solvent present the Root Mean Square Deviation (RMSD) values for 13 C-NMR and 1 H-NMR of 0.07 ppm for C-NMR and 0.03 ppm for H-NMR. In the present B3LYP/cc-pVTZ calculation, we obtain an RMSD of 3.21 ppm between the experimental and theoretical values, which is within the expected range for solvent effects and methodological differences. a This pair of 1 H-NMR shifts were changed to 1.82 ppm and 1.90 ppm so that the RMSD will be 0.03 ppm; if the original data (0.90 ppm and 1.82 ppm) were used for C8 and C9, the RMSD is given by 0.33 ppm, which is 10 times larger.