[xshadow]

Hi

In my book I 've seen the first example of the following picture:


Here LDA acts as a kinetic controller (deprotonation of the position with less steric hindrance)...as usually does


My doubts is for a diketone....here  I have a -CH₂ between 2 C=O group

The deprotonation in that position gives the thermodynamic enolate ( large π-system)
Those two hydrogens are also far more acidic
But there is more steric hindrance


But there are also 2 groups of  terminal CH₃ groups.
The corrispondent enolates are MUCH less stable and those hydrogens much less acid

But there is less steric hindrance

My question is:
Which enolate does   LDA form with  a diketone? the thermodynamic or the kinetic enolate?




Thanks!!!

[spirochete]

I think LDA is an odd choice to deprotonate the 1,3-diketone. You don't need such a strong base. NaOH or NaOR would suffice for 99.999%  deprotonation. If LDA is used, I strongly suspect it will favor the thermodynamic enolate. Probably in the case of the 1,3-diketone, the thermodynamic and kinetic enolate are the same.