Talk:Mod:awc106 module1

1.2 Energy values are excellent. The thermodynamic vs. kinetic argument is picked up on and the importance of bending distortion in the dihydro cpds is well covered. Diagrams and data is clearly presented. Good job.

1.3 Energies are good and the structures and stereoselectivities are well addressed. NB: the product of the reactions with Grignard reagent/aniline should bear a non-aromatic heterocycle with no positive charge on the nitrogen (a dihydro pyridine). The Grignard reagent cannot be modelled specifically because MM2 doesn’t have parameters to deal with Mg2+. These parameters can in fact be manually added.

1.4 Taxol intermediate structures and energies are good and lowest energy conformer is correctly identified. Good definition of a hyperstable alkene.

1.5 The energies are a little high; it is possible that you have found the “wrong” H-bonds in some cases (more than one type is available). The reason for the intramolecular reaction being fast is correct and the factors affecting attack at CO are well discussed. The difference in reactivity of the two systems is still open to debate since analysis of the isomers shows that (in spite of what the literature report suggests) all of them can orientate in a reacting conformation. It appears therefore that MM2 analysis of the starting points gives an incomplete picture.

1.6The structures and MO diagrams appear to be correct as are the IR data for the diene. The dihydro compound is in fact expected to have a stronger C-Cl bond. In the diene this bond is relatively destabilised due to donation of pi electron density from the exo-double bond into the C-Cl sigma* antibonding orbital.

MP The representation of the optimised structures is good as is the tabulation of calculated vs. experimental NMR chemical shifts. It would have been beneficial to also include the differences between these data.