Ethyl acetoacetate alkylation mechanism

The mechanism of the Feist-Benary reaction involves an aldol reaction followed by an intramolecular 0-alkylation and dehydration to yield the furan product. In the example below, ethyl acetoacetate (9) is deprotonated by the base (B) to yield anion 10 this carbanion reacts with chloroacetaldehyde (8) to furnish aldol adduct 11. Protonation of the alkoxide anion followed by deprotonation of the [i-dicarbonyl in 12 leads to... 

Robinson, R. Extension of the theory of addition to conjugated unsaturated systems. II. The C-alkylation of certain derivatives of (i-aminocrotonic acid and the mechanism of the alkylation of ethyl acetoacetate and similar substances. J. Chem. Soc., Abstracts 1916,109, 1038-1046. 

The unusually high acidity of the methylene hydrogens of j8-ketocarbonyl compounds can be used to synthetic advantage. Their unusually low pK values (ca. 9-13, see Table 23-1) allow alkoxide bases to remove a proton from this methylene group essentially quantitatively, giving an enolate ion that may be alkylated to produce substituted derivatives. For example, treatment of ethyl 3-oxobutanoate (ethyl acetoacetate) with NaOCH2CH3 effects complete deprotonation to the enolate, which reacts via the Sn2 mechanism with iodomethane... 

When treated with concentrated alkali, acetoacetic ester is converted into two moles of sodium acetate, (a) Outline all steps in a likely mechanism for this reaction. (Hint See Sec. 21.11 and Problem 5.8, p. 170.) (b) Substituted acetoacetic esters also undergo this reaction. Outline the steps in a general synthetic route from acetoacetic ester to carboxylic acids, (c) Outline the steps in the synthesis of 2-hexanone via acetoacetic ester. What acids will be formed as by-products Outline a procedure for purification of the desired ketone. (Remember that the alkylation is carried out in alcohol that NaBr is formed that aqueous base is used for hydrolysis and that ethyl alcohol is a product of the hydrolysis.)... 

---