[pdffree]

Does anyone know why this reaction fails? is it because wrong base base is used?. Let us assume the wrong base is used, therefore it fails. If the wrong base is used, an aldol condensation results instead. An aldol condensation is a self condensation reaction.

[nj_bartel]

Bulky base - the necessary proton probably isn't accessible.

[azmanam]

The carbon bearing the proton being deprotonated is also not the most acidic proton.  It is not specified in the reaction conditions, but using 1 equivalent of base will result in only the alcohol being deprotonated.

If two equivalents of base are used, the reaction will probably work, although the methyl protons alpha to the carbonyl (the terminal methyl group on the right) is probably deprotonated before the internal methylene protons.

ps. the reaction is called a Frater-Seebach alkylation.

[pdffree]

what  do you think is the  likely product of  the reaction?

[azmanam]

Depends.  Is there 1 equivalent of base or 2?

The text starts with 'if the reaction is done on this compound...'  What was the original compound?  With just the information you've provided, I can think of at least 3 plausible answers, but it will depend on the reaction conditions.

[pdffree]

will it form enone?

and suppose it is 1 equivalent of base, what the product might be?

[azmanam]

will it form enone?

not under basic conditions.  What is the most acidic proton?  That proton will be removed with 1 eq base.  What is generated after removal of the most acidic proton?  How might that react given the rest of the rxn conditions?

[Mitch]

azmanam: So for acetylacetone you wouldn't expect it to take the internal methylene proton? The pKa for acetylacetone is 8.95

[azmanam]

acetylacetone is a different beast entirely.  Acetylacetone exists primarily in the enol form thanks to significant stabilization of the enol tautomer through hydrogen bonding in a low-energy 6-membered ring (see http://en.wikipedia.org/wiki/Acetylacetone). 

Deprotonation will form the enolate between the two carbonyl groups for several reasons - 1) you're not really deprotonating a carbon acid, but rather you're pulling the proton off the 'alcohol' formed through tautomerization (this is one reason the pK_a of acetylacetone is so low).  2) the enolate between the two carbonyl groups is stabilized by 3 resonance structures.

So even under the kinetic deprotonation conditions of LDA, I would still expect acetylacetone to deprotonate the 'methylene' position.

The beta-hydroxy ketone we're talking about here will probably behave differently... although some F-S alkylation is probably formed to some extent.