Talk:ModOne:hhlk2010

Cp: Structures, energies all OK (too many dec. places though!) Good explanation for endo-selectivity. Why exactly is the exo-isomer "less strained"?

NAD: Your lowest energy structure of 5 is good, but I hope you can see that the others have serious problems (wrong carbonyl bond angles!) They are anomalies of the forcefield... For 7, I think there should be another, lower energy structure with the carbonyl "down".

Taxol: Structure 10 is good. For 9, there is a lower energy form if you flip to the "other" chair form of the 6-ring (yours IS a chair, not a twist boat). Why is the alkane less stable than its parent bridgehead alkene?

CCl2: Your HOMO looks to be centred on the anti-alkene to me... Your stretching frequencies all look good. Your analysis is a little confused though...why would a higher stretching frequency be expected to make a bond more reactive? What about the bond lengths?

Mini-project: There is no point comparing MM2 results for 14 and 15 - they are not isomers. Similarly, you were meant to think about how you would distinguish 15 from the other product regioisomer (the lactone with the O on the other side of the carbonyl!) In fact, the regioselectivity of this reaction is quite interesting. Even for the one product 15 that you did calculate the 13C for, you should have tried to quantify the agreement between calculation and experiment. The values in the middle of the table are a LONG way out - there is something wrong. I suspect you have compared the wrong carbons.