By GABRA SOLIMAN and LATIF RATEB.Ethyl 6-o-methoxyphenyl-, 6-p-dimethylaminophenyl-, and 6-2'-fury1-2 : 4-dioxohex-5-enoates (11) have been synthesised ; the known methyl and ethyl esters of this series were interconverted by alcoholysis.S i x of these esters were converted into 2 : 6-disubstituted 4-pyrones (V) on bromination, and dehydrobromination with potassium acetate. They were converted into l-phenyl-5-styrylpyrazole-3-carboxylic esters (VI) , the structures of which were determined by ozonolysis, decarboxylation, and hydrolysis to 1-phenylpyrazole-3-carboxylic acid. 3 : 5-Disubstituted isooxazoles (X) have also been prepared.SYNTHESES and properties of &unsaturated 1 : 3-diketo-esters have attracted the attention of various chemists.1 The aromatic prototype, ethyl 2 : 4-dioxo-6-phenylhex-5-enoate (I1 ; R = Et, R' = Ph) was first prepared by Schiff and Gigli and later by R ~h e m a n n . ~ Similarly, Ryan and Algar,4 and Ryan and PlunkettJ5 prepared other hexenoates by the action of sodium on methyl oxalate and substituted methyl styryl ketones (I).The present investigation involves the synthesis of ethyl 6-o-methoxyphenyl-, 6-$dimethylaminophenyl-, and 6-2'-furyl-2 : 4-dioxohex-5-enoates (11) as well as interconversion of the methyl and ethyl esters by alcoholysis. These esters were obtained as described in the Experimental section in good yields unobtainable otherwise. Condensation of $-dimethylaminostyryl methyl ketone gave the desired ester and a high-melting

Abstract A series of benzoylacetaldehyde benzoylhydrazones were prepared and characterised. Their UV, IR, and 1H NMR spectra suggest the enol-imine structure rather than the keto-imine form of analogous Schiff bases. The pKa values of these aroylhydrazones were also measured and correlated with the Hammet substitution constants. Attempted cyclizations of these open-chain aroylhydrazones afforded the corresponding 5-hydroxy-2-pyrazoline compounds rather than the expected pyrazoles.

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