Talk:Mod:Rhubarbicon2802

1.1 Brief intro to the method/problem etc would have been nice. Why is the endo-adduct favoured kinetically? You’re along the right lines for the comparison of the hydrog isomers.

1.2 Your structure and energy for 5 look good. The Grignard addition will NOT be thermodynamically controlled (it can’t reverse). You can come up with a rationale for the observed stereochem just from your model of 5 (hint: which face is the C=O on?) The structure and energy of the JMol structure for 7 also look good. Did you actually model another conformer? How do your results explain the observed stereochem?

1.3 Your structures and energies are spot on. There’s another key reason for the low reactivity of the alkene that you’ve missed… (Also – a “HOMO” is by definition occupied, so not where electrons will go….)

1.4 Your structures for 13 are a bit high in energy, because they have the rings in boat conformations rather than chairs. For 14: the second (N-eq) structure is great. The other (“N-ax”) has the ring N-missing…and the N-substituent has ended up equatorial! Nice idea to look at the reaction products as well.

1.5 Good

Mini-project Well done for choosing your own! As you say, you’d be able to tell the two alkene isomers apart in this case by 1H NMR. Remember the two terminal alkene protons are different and so probably won’t be just a singlet…. A more interesting question might have been how they knew that the trisubstituted alkene isomer was E and not Z? That wouldn’t be possible by simple 1H NMR, but 13C correlation might help. To really make progress, you needed to try to assign the literature 13C data to particular carbons in the structure. That would have allowed you to see which carbons gave good agreement, and which didn’t. Also, a comparison between the two sets of results to check the isomers are the right way round.

Overall very good – really nice to see some of your own ideas and experiments in there!