Note: Malonic ester synthesis begins with alkylation of a malonic ester via a double active enolate intermediate. Note that the choice of base used should match the ester to avoid messy trans-esterification results.

Note: Acetoacetic acid synthesis starts with alkylation of acetoacetic acid via a double active enolate intermediate.

Note: Malonic ester synthesis with a di-halide

Note: Treatment with a second equivalent of base will yield an intramolecular reaction and ring closure.

Note: Claisen condensation when an enolate reacts as a nucleophile for acyl substitution against an ester. This means treating an ester with a mild base will result in a dimerization reaction.

Note: The result of a Claisen condensation is a beta-keto ester with a double active enolizable hydrogen in between that is readily deprotonated by the base.

Warning: Claisen condenstations are reversible reactions and are generally only favored because of the highly favorable deprotonation of the resulting beta-keto ester. However, if no such enolizable hydrogen is available in the result, the reaction tends not to be favorable or reliable.

Note: Dieckmann condensation is simply an intramolecular Claisen condensation.

Note: Crossed Claisen condensations are possible, but a mixture of many products often results. Using one ester that has no enolizable hydrogens can help, but some mixture of products may still result.

Note: Crossed Claisen condensation using a ketone enolate is more reliable, especially if the ester has no enolizable hydrogens.

Note: Specialized formic ester with no enolizable hydrogens in a crossed Claisen condensation offers a means to introduce a formaldehyde group.

Note: Specialized carbonate ester with no enolizable hydrogens in a crossed Claisen condensation offers a means to introduce an ester group.

Note: Enolate preparation with a less bulky base at room temperature will favor more substituted 'thermodynamic enolates.' However, a milder base like an alkoxide is not strong enough to produce these in quantitative yield and thus an aldol addition / condensation reaction is more likely to result (see Aldol Chemistry section).

Note: An 'active' methylene group flanked by two electron withdrawing groups (e.g., carbonyls) has much more acidic alpha hydrogens and can be readily deprotonated by alkoxide bases.

Note: The result after alkylation of a double activated enolate can itself be deprotonated again to yield another double activated enolate.

Note: Aldehydes may be deprotonated with base to yield enolates, but aldehydes are also good electrophiles resulting in the likely aldol addition of an enolate to an aldehyde to form a beta hydroxy carbonyl.

Note: Under basic reaction conditions, beta hydroxy carbonyls can be dehydrated to alpha, beta unsaturated carbonyls via an E1cb mechanism (not E2!)

Note: Ketones are not as good electrophiles as aldehydes but can still undergo base-driven aldol addition and condensation.

Note: Crossed aldol condensation with a ketone and an aldehyde with no enolizable hydrogens makes for a reasonably reliable reaction. Note that the aldol condensation product predominates here over aldol addition with the extra stabilization granted by conjugation with aromatic ring.

Note: Crossed aldol condensation with a double active enolate and an aldehyde.

Note: Intramolecular aldol condensation.

Note: Michael addition: Enolate ions are relatively 'soft' nucleophiles that will prefer to add by conjugate addition to alpha,beta unsaturated carbonyls.

Note: Robinson annulation: Michael addition of a (cyclic) ketone enolate to an alpha,beta unsaturated ketone. After some proton transfers, the result of the Michael addition is itself perfectly setup to undergo an intramolecular aldol condensation back against the original (cyclic) ketone. This overall reaction is known as a Robinson annulation.

Note: Another Robinson annulation with different reactants illustrates how different ring sizes and substituents can be prepared on the product.

Note: Amino acid synthesis by alkylation of amino-malonate derivatives. Note that this is directly analogous to malonic ester synthesis.