Ethyl 2- -3-oxobutanoate

The systematic lUPAC name of ethyl acetoacetate is ethyl 3 oxobutanoate The presence of a ketone carbonyl group is indicated by the designation oxo along with the appro priate locant Thus there are four carbon atoms m the acyl group of ethyl 3 oxobutanoate C 3 being the carbonyl carbon of the ketone function... 

Conjugate base of ethyl 3 oxobutanoate (weaker base)... 

The product described here, 4-(4-chlorophenyl)butan-2-one, was previously prepared in the following ways a) by reduction of the corresponding benzalacetone, b) by catalyzed decarbonylation of 4-chlorophenylacetaldehyde by HFeiCO) in the presence of 2,4-pentanedione, - c) by reaction of 4-chlorobenzyl chloride with 2,4-pentanedione under basic catalysis (K2CO3 in EtOH), d) by reaction of 4-chlorobenzyl chloride with ethyl 3-oxobutanoate under basic catalysis (LiOH), - and e) by reaction of 3-(4-chlorophenyl )-propanoic acid with methyl lithium. - ... 

Conjugate base of Hydronium ion Ethyl 3-oxobutanoate Water... 

Copper(Il) complexes 18a-f of methyl or ethyl 3-oxobutanoate la, 2-bromo-3 oxobutanoate lb, 2-(anilinocarbonyl)-3-oxobutanoate Ic, 3-oxo-3- rfienylpro-panoate Id, 2-bromo-3-oxo-3-phenylpropanoate le, or 3-aniHno-2-benzoyl-3-oxopropanoate If were reacted with phenylhydrazine hydrochloride and sodium ( )... 

Krohn and Stenns reacted ethyl 3-oxobutanoate with l-(4-methoxyphenyl)hy-drazine 32 and managed to obtain pyrazol-3-one 33 and pyrazole 34 in 65 and 20% yield, respectively (89AP351) (Scheme 9). 

The reaction of ethyl 3-oxobutanoate with 4-aryltetrahydropyridazine-3,6-di(Mie 3-hydrazones 60a-d afforded the corresponding hydrazonobutanoates 61a-d. When heated with ethanolic sodium ethoxide, compounds 618-d cyclized to the sodium derivatives 62a-d which, upon acidification, gave the respective pyrazol-3-one derivatives 63a-d (97JHC389) (Scheme 19). 

A widely used approach is the condensation of (amino, methylamino, or ethyl-amino)benzohydrazides 73a with ethyl 3-oxobutanoate in boiling ethanol... 

In the reaction of arylhydrazides 73a, benzylhydrazide 73b, aryloxymethylhy-drazides 73c, or 1 -styrylhydrazide 73d with ethyl 3-oxobutanoate in boiling diox-ane, the corresponding hydrazones 86a-d were obtained in good yields. The latter... 

Ethyl 3-oxobutanoate, commonly called ethyl acetoacetate or ace tome tic ester, is much like malonic ester in that its ct hydrogens are flanked by two carbonyl groups. It is therefore readily converted into its enolate ion, which can be alkylated by reaction with an alkyl halide. A second alkylation can also be carried out if desired, since acetoacetic ester has two acidic a hydrogens. 

The ethyl ester can also be prepared from ethyl acetoacetate (ethyl 3-oxobutanoate) by the method of Rodionov8 as well as via Steinkopf s method.3 Ethyl nitroacetate can be prepared in >70% yields from the dipotassium salt, ethanol, and sulfuric acid, with the addition of anhydrous magnesium sulfate in order to avoid the Nef reaction.9 The propyl and 2-propyl esters can also be obtained by this method. 

Aliphatics Fluorination Investigated in Micro Reactors Cas/liquid reaction 3 [CL 3] Fluorination of ethyl 3-oxobutanoate (ethyl acetoacetate) [15, 16]... 

Optically pure a, . (R)-3-hydroxybutanoates can be obtained by alcoholysis of poly-(R)-3-hydroxybutanoate, a fermentation product of fructose by Alcaligones eutrophus.4 (S)-Ethyl 3-hydroxybutanoate in 84-87% ee can be synthesized in 57-67% yield on a decagram-scale by an Organic Syntheses procedure6 using bakers yeast reduction of ethyl 3-oxobutanoate with the aid of sucrose.7 In order to obtain enantioselectivity as high as 95-97% ee, the substrate concentration should be kept below 1 g/L.6... 

Microwave-mediated transesterification of commercially available neat poly(styr-ene-co-allyl alcohol) with ethyl 3-oxobutanoate, ethyl 3-phenyl-3-oxopropanoate, and diethyl malonate provided the desired polymer-supported /i-dicarbonyl compounds (Scheme 12.18) [65]. Multigram quantities of these interesting building blocks for heterocycle synthesis were obtained simply by exposing the neat mixture of reagents to microwave irradiation in a domestic microwave oven for 10 min. 

The Rh complex of the chiral Cj symmetry Josiphos 47 is also effective for the enantioselective hydrogenation of ethyl 3-oxobutanoate [27]. 

Based on hydrogenations of model substrates, several new ligands promise to have a similar potential as those described above. For example, Ru-Solphos (Solvias) catalysts have been shown to hydrogenate various yS-keto esters and / -diketones with ee-values up to >99% and TONs of up to 100000 (for ethyl-3-oxobutanoate) [75], while Ru-Synphos (Synkem) [107] catalysts achieved 99.4% ee at an SCR of 7000 for the hydrogenation of ethyl acetoacetate (for ligand structures, see Fig. 37.28). 

The results actually showed a deracemization of the racemic hydroxyester 10 as opposed to enantioselective hydrolysis with formation of optically pure (R)-hydroxyester 10 and only 20 % loss in mass balance. Small quantities of ethyl 3-oxobutanoate 9 (<5%) were also detected throughout the reaction, leading the authors to suggest a multiple oxidation-reduction system with one dehydrogenase enzyme (DH-2) catalysing the irreversible reduction to the (R)-hydroxy-ester (Scheme 5). 

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