الفهرس 
Synthesis of phthalazine derivativesOnly 14 pages are availabe for public view
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Abstract
Refluxing our acetohydrazide scaffold 4 with diethyl malonate in dioxane for 10 h to obtain the isolable ethyl 3-(2-(2-(4-(3,4-dimethylphenyl)-1- oxophthalazin-2(1H)-yl)acetyl)hydrazineyl)-3-oxopropanoate (11) and then cyclizing the isolated intermediate 11 by refluxing in dioxane for an extra 30 h, or via grinding of acetohydrazide derivative 4 with diethyl malonate in the presence of a few drops of acetic acid at room temperature for only 30 min gave rise to pyrazolidine-3,5-dione derivative 12. The exploration of the
reactivity of active methylene nucleophiles on acetohydrazide scaffold 4, the latter compound was allowed to react with malononitrile in dioxane to submit the cyclization product 3,5-diamino-1H-pyrazol derivative 13. Additionally, a condensation reaction was observed, and oxoindolin derivative 14 was isolated when phthalazine acetohydrazide derivative 4 was treated with isatin. Refluxing acetohydrazide scaffold 4 with maleic anhydride in ethanol to obtain the acyclic product [4-(2-(2-(4-(3,4-dimethylphenyl)-1-oxophthalazin-2(1H)- yl)acetyl)hydrazineyl)-4-oxobut-2-enoic acid (15) was isolated. The reaction of phthalazine acetohydrazide derivative 4 with acetic acid in the presence of phosphorous oxychloride didn’t afford the expected cyclized oxadiazol derivative 16a, but rather an N-acetylation reaction occurred at the terminal amino of acetohydrazide derivative 4 to afford the N’-acetyl acetohydrazide 16 as the sole product. In another attempt to have an access to the desired cyclization product 16a, N’-acetyl acetohydrazide derivative 16 was allowed to reflux with acetic anhydride; however, no cyclization reaction was observed. Alternatively, O-acylation reaction was reported, and the corresponding diacetyl derivative 17 was attained as the only product (Scheme 2).