Prediction of the ^13C NMR Chemical Shifts of 9,10-Dihydrophenanthrene Analogues by the GIAO Method

摘要

After the geometry optimizations at the B3LYP/6-31＋G（d,p） level, the NMR calculations of a series of 9,10-dihydrophenanthrene analogues have been carried out by GIAO method at the HF/6-31＋G（d） level. The calculated ^13C NMR chemical shifts are in agreement with the observed values. By a series of linear correlation equations （δpred = a ＋ bδcal.c） of the ^13C chemical shifts, accurate prediction of ^13C chemical shifts was achieved for the new 9,10- dihydrophenanthrene compound, for which the predicted ^13C NMR chemical shifts are in quite good agreement with the experimental values. The linear correlation between δpred and δexptl is excellent, and the square of correlation coefficient, r^2, is up to 0.9973. The maximum absolute difference between δpred and δexptl, △δ, is 4.5 ppm, and the rms error between δpred and δexpt is 2.55 ppm. In the meantime, according to the theoretical predicted result, we could confirm that the new 9,10-dihydrophenanthrene analogue is erianthridin （2,7-dihydroxy-3,4-dimethoxy-9,10-dihydro- phenanthrene）.