Condensation of 4-substituted-but-3-en-2-ones (1) with ethyl oxalate gave ethyl 6-aryl-2,4-dioxo-62-hexenoates (2) and were interconverted to the methyl esters by alcoholysis. Compounds (2) were converted by hydrazine or arylhydrazine into the corresponding ethyl 1-H/aryl-5-substituted-pyrazole3-carboxylates (3), which were hydrolysed to the acids (4). With hydroxylami ne, the ethyl hexenoates (2) afforded 3 ,5-di subs tituted-i soxazo 1 es (5), whereas, with o-phenylenediamine they gave oxyquinoxaline derivatives (6).The 1,3-di keto-es ters (2) on reacti on with acyl hydrazi nes gave the acylhydrazones (7) which were cyclized to the corresponding N-acylpyrazoles (8). Reaction of (1) with arylhydrazines afforded the corresponding hydrazones (9) which on boiling with ethanol containing two drops of HCl underwent cycl ization to the pyrazol ines (10). Oxidation of (10) with an excess of bromine-water produced the brominated pyrazole derivatives (11). Furthermore, the condensa t i on of the ex,8 -unsa tura ted ketones (1) with acyl hydrazi nes furnished the corresponding hydrazones (12).
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