Ethyl ethoxalylacetate

Ethyl ethoxalylpropionate has been prepared by the Claisen condensation of ethyl oxalate with ethyl propionate as above, and by the alkylation of ethyl ethoxalylacetate. ... 

The same substrate (218) and ethyl ethoxalylacetate (Et02CC0CH2C02Et) gave 3-ethoxycarbonylmethyl-2(l//)-quinoxalinone (221, R = H) (EtOH, reflux, 3 h 80% ° likewise but 15 min 64%) the homologous substrate, 3,6-dimetyl-l,2-benzenediamine, and the same synthon gave 3-ethoxycarbonyl-methyl-5,8-dimethyl-2(l//)-quinoxalinone (221, R = Me) (AcOH, reflux, briefly 61%). ... 

There have been some further examples of the use of the Conrad-Limpach reaction on substituted 5-aminoquinolines for the synthesis of 4-hydroxy-1,7-phenanthrolines, although the products (see Section IV,F,1) should properly be designated as phenanthrolinones.169 Hot diphenyl ether is often employed as the medium for ring closure.170 Ethyl trifluoro-acetoacetate has been used successfully in place of ethyl aceto-acetate, and this variation has allowed entry to 2-trifluoromethyl-substituted 1,7-phenanthrolines.96 Extensions of the Conrad-Limpach type of synthesis starting with m-phenylenediamine (20) and utilizing diethyl ethoxymethylene malonate or ethyl ethoxalylacetate, reagents frequently used in quinoline syntheses, have afforded, after hydrolysis,... 

The diazo compound from methyl benzoylacetate gives phenylcarbo-methoxyketene in 70% jdeld when the final decomposition is carried out in refluxing xylene, but it is converted largely to the ester of phenyl-malonic acid by heating in the absence of a solvent. The ethyl ester of ethylmalonic acid is the principal product from the decomposition (in the absence of a solvent) of the diazo compoimd obtained from ethyl pro-pionylacetate. A small amoimt of the ketene evidently was formed also. The diazo compound obtained from ethyl ethoxalylacetate on decomposition in warm xylene gives 54% of dicarbethoxyketene. ... 

Two procedures of synthesis of aminomethylquinoxalines 1 have been developed. One of them involves three stages (a) condensation of ethyl ethoxalylacetate 4 or dimethyl acetylenedicarboxylate with 1,2-DAB to give quinoxalines 5, (b) the reaction of the latter with isopentyl nitrite, and (c) reduction of resulting oximes 6 (Scheme 4.2) (Danswan et al. 1982 Ager et al. 1988). 

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