THEORETICAL STUDY ON THE STRUCTURE TRANSFORMATIONS OF CRYPTOTANSHINONE AND TANSHINONE I WITH HYDRION OR HYDROXIDE ION

摘要

The effects of hydrion and hydroxide ions on the structure transformations of Cryp_totanshinone and Tanshinone I were investigated using the density functional theory at the Becke three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional B3LYP/6-31+G(d) level. The solvent effects were assessed using the polar_ized continuum model. Our results revealed that the furan ring of Tanshinone I and dihydrofuran ring of Cryptotanshinone could be opened with the attack of hydroxide ion. The reaction of furan ring-opening proceeds via two pathways, while the reaction of dihydrofuran ring-opening is reversible. In the case of hydrion, the furan or dihydrofuran ring could not be opened. All of the relevant Gibbs free energy barriers are increased with the increase of the polarity of the solvents. The results are in reasonable agreement with the experimental observation.