Ethyl acetoacetate, reaction with

Coumarin can also be formed by the reaction of phenol with diketene (40). Similarly, diphenols can react with hydroxycarboxyUc acids or beta-ketoesters to give hydroxycoumaria derivatives. The reaction of resorciaol with malic acid produces umbeUiferone (7-hydroxycoumaria) and its reaction with ethyl acetoacetate gives beta-methylumbeUiferone (7-hydroxy-4-methylcoumaria). 

The reaction with ethyl acetoacetate has been extended to glycolaldehyde, and to carbohydrates other than n-glucose, by employing different experimental conditions it is probably applicable to aldoses in general. With d-fructose, yields are lower, but two molar proportions of water are liberated and a crystalline product results. This has a constitution similar to that of II but with the D-omhfno-tetrahydroxybutyl chain at the /3-position on the furan ring. The reaction has been applied successfully to other ketoses and... 

Methylcoumarins bearing hydroxy and other electron-donating groups can be synthesized from the corresponding phenols by reaction with ethyl acetoacetate in the presence of sulfuric acid. Hydrolysis of the ester group in the product then allows the lactone ring of the coumarin to form (Scheme 5.6). 

Amino-9-ethylcarbazole and its 6-methyl-homolog underwent the Conrad-Limpach reaction with ethyl acetoacetate, closure occurring at C-4 giving 185 (R = H or Me). 1-Aminocarbazole condensed with diethyl ethoxymethylenemalonate to give 186, which was thermally cyclized... 

Although earlier investigations suggested that a Pechmann reaction on 3-substituted or 3,4-disubstituted phenols yielded only one product, it is now clear that this is not always the case (81T2021). The failure of earlier workers to isolate a second product is readily understood from the data in Table 6. As yet, it is not known whether this behaviour is a general feature of m-substituted phenols. The lack of formation of the 5- or 5,6-isomer in the reactions with ethyl acetoacetate may be a result of steric hindrance by the 4-methyl substituent. 

From the point of view of selectivity, results from Table 3, clearly show that zeolites are much more selective catalysts, without side reactions, for the desired condensation reaction with ethyl acetoacetate than either pyridine or piperidine. 

Esterification of amino acids. The amino group of an amino acid can be protected as the enamine 1, formed by reaction with ethyl acetoacetate and a base in benzene/ DMSO. After alkylation the protective group is removed by addition of an acid, particularly TsOH, to provide amino acid ester salts (equation I). 

The reaction with ethyl acetoacetate is exceptional, a condensation product of amino-acid (1 mol.) with acetone (1 mol.) resulting. This product cannot be obtained directly from acetone. 

M-Acetylsaccharinyl acid derivatives 408, which are structurally related to COX-2 inhibitor celecoxib, were designed and synthesised [133] from M-saccharinyl acetate 407a, prepared via the reaction of ethyl bromoacetate with sodium saccharin by heating the reactants in DMF (see [133]). Its transformation into the corresponding hydrazide 407b and subsequent reaction with ethyl acetoacetate, /3-diketones and maleic anhydride, afforded the heterocyclic compounds 408 [134] (Scheme 97). 

Benzofuroxan (150) on reaction with ethyl acetoacetate provides the methylquinoxaline 151, which on bromination gives the bromomethyl derivative 152. Treatment of this compound with amines gives the monooxopyrrolo compound 154. The 2-methyl derivative 154 (R = Me) was also prepared directly from benzofuroxan by reaction with the JV-methylpyrrolinone 153. The products 154 are claimed to be antibacterials and animal growth promotants. ... 

The pyrrole 203 was prepared by reducing the phenylosazone 201 to give 1-amino-l-deoxy-D-g/Mcoheptulose (202) followed by reaction with ethyl acetoacetate (76AQ855). 

The Belousov-Zhabotinskii reaction with ethyl acetoacetate (3-oxobutanoic acid, ethyl ester CH COCH COOC H EA) as organic substrate is of interest as the batch reaction has shown both high and low frequency oscillations in the same experiment, (1), and because no bubbles of gaseous products are formed. 

Several different unprotected carbohydrates have been successfully deployed in the cascade reactions with ethyl acetoacetate 19 by subsequent systematic studies. The results of these investigations are depicted in Schemes 2.6 (pentoses) and 2.7 (hexoses). 

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