Ab initio analysis of the Cope rearrangement of germacrane sesquiterpenoids

作者：Setzer William N^*

来源：Journal of Molecular Modeling, 2008, 14(5): 335-342.

DOI：10.1007/s00894-008-0274-3

• density functional theory
• ab initio molecular orbital theory
• germacrane sesquiterpenoids
• elemane sesquiterpenoids
• Cope rearrangement

The energetics of the Cope rearrangement of 17 germacrane sesquiterpenoids to their respective elemane forms have been calculated using both density functional theory (B3LYP/6-31G*) and post Hartee-Fock (MP2/6-31G**) ab initio methods. The calculations are in qualitative agreement with experimentally observed Cope rearrangements, but the two methods give slightly different results. MP2 calculations generally show more favorable elemene energies compared to the respective germacrenes (by around 3-4 kcal mol(-1)) and smaller activation energies (by 2-3 kcal mol(-1)). Additionally, neither method is accurate enough to consistently reproduce the germacrene/elemene equilibrium. Apparently, the generally small energy differences between the two forms in these sesquiterpenoids cannot be adequately reproduced at these levels of calculation.

• 出版日期2008-5