Talk:Mod:yongyao1C
Comments
Cyclopentadiene (0.20)
Taxol (0.25)
The chair conformation is indeed the lowest energy conformation. However, you need to check the other conformations as well. When you look at a system, you can never tell if you've found a global minimum. The Cyclohexane ring might be twisted by the substituents, so in theory a boat conformation (for example) could have been more favourable.
You'll need to double-check. For example, the lowest energy structure for the dithiolane is not the chair conformation, which explains some of the differences between calculation and literature.
The calculation of the olefine proton is off. This proton's signal is actually more important than the aliphatic signals. The olefine proton is also very sensitive to changes in the conformation, hence the difference between calculation and literature. That tells us that the actual conformation in solution is different.
Overall very good explanation!
Well done on avergaging the methyl signals!
Epoxide (0.05)
Nicely done!
NMR (0.05)
Very detailed! Nice!
Optical Rotation and TS (0.35)
That looks nice, but the OR data (and thus your conclusion) need more critical considerations. The Optical rotation is not a straightforward value. If you lookup the Styrene molecule on Reaxys you'll find that the R-configuration sports alpha values between -25° and +46°. You can't be sure that the literature value you found is correct.
Also, below 100° the attribution of alpha values is not completely reliable (check the infos on the wiki).
Which means, your data looks really good. But it could be completely wrong and you won't know until you do the experiments yourself.
Be more critical with your conclusions and with the data yoou get (your own as well as other data).
Excellent section on the stereoselectivity of the Shi catalyst.
Please write formula in a general way (K = exp(-ΔG/RT) ) and put the results (k, ee) into a table. It makes your text much nicer to read and to compare to the other results on one glance.
Good final thoughts on how reliable the calculational method might be.