The key step in the synthesis of Xestoquinone is an intramolecular Diels-Alder addition
(see full question here). A number of
possible isomers can form. The easiest way to predict which is actually formed is to
contruct quantitative modelular models, shown below with the calculated energies. These
models are constructed using the semi-empirial PM3 method, although mechanics based methods
give similar results.
The reaction sequence here is:
To use these models, move the mouse cursor to the model and press the mouse button (rhs button
for a windows machine). From the menu that appears, select File/Save molecule as, and save the model
to your local hard disk. Select a modelling program (e.g. Weblab Viewer/Medchem Explorer, CAChe, Chem3D, MacMolPlt/GAMESS), open the
saved file, and then proceed with the desired calculation.