New answers tagged regioselectivity
1
An explanation can be provided by frontier molecular orbital theory. The LUMO coefficient is higher on the C4 vs C2. This is a general effect meaning that an EWG para to the leaving group is more reactive than ortho. See 4-halopyridines vs 2-halo and 4-nitrobenznes vs 2-nitro. There could also be an effect from the repulsion between the nitrogen lone ...
4
As @Zhe and @Zenix have mentioned, you have to hope that there is a difference in the rate of enolate formation to differentiate the two ketones.
To do this cool a rigourously dried solution of the diketone and a trapping reagent ($\ce{Me3SiCl}$ if you're doing an anhydrous workup otherwise TIPS-Cl or MeI) to $\mathrm{-75 \, ^\circ C}$ and slowly add 1 eq. ...
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