Talk:Mod:CN2209

Which 1,4-repulsive interaction are you talking about? If it's the torsion component of the MM2 energy, it has little to do with Figure 3. Torsion is all about dihedral angles.
Good explanation of the thermodynamics vs kinetics consideration.
" two more stereospecific dihydro derivatives": wrong term.
Good analysis on the bend components of 3 and 4.

Correct optimised structures of 9 and 10.
Don't speculate about things you don't know in any scientific communication: MM2 vs MMFF94.
Calculated energy of H2 in MM2 is 0 kcal/mol.
Overall, I think you understand the concept of hyperstable alkenes, and how they come about.
Energy of 9-chair off by 1 kcal/mol. Assumed typo but must subtract 2%.

How was the structure optimised? It's actually very important.
Correct prediction of reactivity with Cl2C:
Reasonable account for the vibrational frequencies. As often, you also neglected the bond lengths of the bonds in question.

A isn't the lowest energy which could be found. You made the mistake of taking the lowest energy conformation in MM2 and perform PM6 on it.
You failed to spot A = C and B = D in PM6 but not in MM2. This is a perfect case for comparing MM2 and PM6 as computational methods in organic chemistry.
A translation from the difference in energy for C/C' and D/D' to equilibrium constants would give some numbers to explain the diastereoselectivity here. It's very important to be able to translate energy in kcal/mol to observed selectivity.

You failed to cite the references for the ruthenium-catalysed reactions you mentioned.
Overall, your comparison is flawed and your question not well defined. You should have compared experimental data with both calculated spectra, and see if it fits the correct prediction better. Focus should have been on the carbons which one can predict to have significantly different chemical shifts between two structures, rather than average over the whole structure.
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