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Ethyl 3-hydroxy- 3-methylbutanoate (90%)

Methyl butanoate

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Lithium enolate of methyl butanoate

Grignard reagent is consumed, but the only organic product obtained after working up the reaction mixture is ethyl acetoacetate. Why? What happens to the Grignard reagent?

Methyl butanoate (stronger acid)
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The reaction of ethyl (methyldiphenylsilyl)propanoate (1) with primary or aryl Grignard reagents results in the formation of the -silyl ketone or a 1,1-disubstituted 1-propene., For example, the reaction with in refluxing THF for several hours leads to 1,1-diphenyl-1-propene in good yield (eq 1).

Ethyl 3-oxobutanoate(ethyl acetoacetate) Ethanol

methyl from methanol, ethyl from ethanol and propyl from propanol etc.
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Ethyl acetoacetate (acetoacetic ester), available by the Claisen condensation of ethyl acetate, has properties that make it a useful starting material for the preparation of ketones. These properties are

(c)Bromine reacts rapidly with both diethyl malonate and ethyl acetoacetate. The reaction is acid-catalyzed and liberates hydrogen bromide. What is the product formed in each reaction?

Lithium enolate of 2,2-dimethyl-3-pentanone

Step 1: Proton abstraction from the carbon atom of ethyl acetate to give the corresponding enolate.
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21.28The use of epoxides as alkylating agents for diethyl malonate provides a useful route to - lactones. Write equations illustrating such a sequence for styrene oxide as the starting epoxide. Is the lactone formed by this reaction 3-phenylbutanolide, or is it 4-phenylbutanolide?

The preparation of ethyl cyanoacetate proceeds via ethyl chloroacetate and begins with acetic acid. Write a sequence of reactions describing this synthesis.

5-Hydroxy-2,2,4- trimethyl-3-heptanone (81%)
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  • Conjugate base of ethyl 3-oxobutanoate (weaker base)

    Methyl 2-ethylbutanoate (92%)

  • Ethyl 2-methyl-3-oxopentanoate (81%)

    Larson, G. L. 2001. Ethyl 2-(Methyldiphenylsilyl)propanoate. e-EROS Encyclopedia of Reagents for Organic Synthesis. .

  • Conjugate base of ethyl 3-oxobutanoate (stronger base)

    Wawrzeñczyk, Synthesis of Chiral Odoriferous Oxy-derivatives of 1,5,5-Trimethylcyclohexene, Polish J.

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Ethyl 3-oxobutanoate (weaker acid)

The anion produced by proton abstraction from ethyl acetoacetate is nucleophilic. Adding an alkyl halide to a solution of the sodium salt of ethyl acetoacetate leads to alkylation of the carbon.

1-Hydroxy-2,4,4- trimethyl-1-phenyl- 3-pentanone (78%)

(c)What ketone would you isolate after treatment of the Claisen condensation product of ethyl phenylacetate with sodium ethoxide and allyl bromide, followed by saponification and decarboxylation?

Triethyl 2-methylpropane- 1,1,3-tricarboxylate (95%)

PROBLEM 21.3Give the structure of the product obtained when ethyl phenyl- acetate (C6H5CH2CO2CH2CH3) is treated with each of the following esters under conditions of the mixed Claisen condensation:

Methyl 2-methyl-3-oxo- 3-phenylpropanoate (60%)

Section 21.9Michael additionof the enolate ions derived from ethyl acetoacetate and diethyl malonate provides an alternative method for preparing their - alkyl derivatives.

Diethyl malonate 6-methyl-2-cyclohexenone NaOCH2CH3, ethanol

nail varnish remover (the solvent propanone/ is also used), but also in paints, glues and ink formulations as a medium compatible with the other ingredients.

Diethyl malonate 1-bromo-2-methylbutane NaOCH2CH3, ethanol

Figure 21.1, the Claisen condensation product is present in only trace amounts at equilibrium. Ethyl 2-methylpropanoate, for example, does not give any of its condensation product under the customary conditions of the Claisen condensation.

Methyl propanoate is an important precursor ..

For related papers on the use of -trimethylsilylacetates in the synthesis of ,-unsaturated esters, see: (c) Shimoji, K.; Taguchi, H.; Oshima, K.; Yamamoto, H.; Nozak, H.

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