Talk:Jb406-1

Part 1.1: Energies for 1 and 2 are fine, but you should have shown your minimised structures. The formation of 2 is a cycloaddition, not an electrocyclic reaction. Both 1 and 2 would be formed via Huckel TSs, so there’s something more to this! Energies for 3 and 4 also fine. You haven’t discussed why 4 is lower in energy than 3. Your argument about likely rates of attack on the two alkenes is fine.

1.2 You should have given the energy of 5. Were there any other conformations with the carbonyl “down”? For 7, you should have found a more stable conformation with the carbonyl “down”. Based on this, you’d need to alter your argument for the stereocontrol – i.e. the nucleophile doesn’t H-bond to the carbonyl in this case!

1.3 Again, you should have shown your structures so I could inspect them. Your energies are too high, which makes me suspect that your 6-rings are in boat rather than chair conformations.

1.4 Hard for me to judge your structures because you haven’t given energies or rotatable (Jmol) structures. Actually, this is quite a complex problem to analyse – we think it requires more modelling than the paper suggests!

1.5 You should have compared the IR stretching frequencies, especially C=C, for the various compounds

Mini-project: You have shown pictures of the calculated and predicted spectra for the two isomers – but it’s hard to tell anything just by looking at these! You should have tried to quantify the correlation between the calculated and predicted spectra to see how well they compare. Where in particular do the two isomers differ? Given that they didn’t do 13C predictions, how do you think the authors assigned the structures?

Overall – it’s a pity you didn’t include all of your optimised structures, as it’s hard for me to judge the report without them. In the mini-project in particular, you did the calculations, but more analysis of the results is needed.