Heterocyclizations of 5-methylpyrazol-3-amine with unsaturated arylaliphatic carboxylic acid derivatives |
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Authors: | V V Lipson S M Desenko M G Shirobokova O V Shishkin S V Shishkina |
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Institution: | (1) Danilevskii Institute of Endocrinic Pathology Problems, Academy of Medical Sciences of Ukraine, ul. Artema 10, Kharkiv, 61002, Ukraine;(2) State Scientific Enterprise Research and Technology Association “Institute of Single Crystals”, National Academy of Sciences of Ukraine, Ukraine |
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Abstract: | Cyclocondensation of 5-methylpyrazol-3-amine with methyl cinnamate and arylmethylidenemalonic acids in DMF and methanol leads to the formation of 7-aryl-2-methyl-6,7-dihydropyrazolo1,5-a]-pyrimidin-5(4H)-ones. Arylmethylidenemalonic acids react with the title amine at a ratio of 1:2 in nitrobenzene to give 4-aryl-3,5-dimethyl-1,7-dihydrodipyrazolo3,4-b:4′,3′-e]pyridines. Heterocyclizations of 5-methylpyrazol-3-amine with 5-arylmethylidene-2,2-dimethyl-1,3-dioxane-4,6-diones or their precursors, para-substituted benzaldehydes and 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum’s acid) in all solvents (methanol, DMF, and nitrobenzene) give the corresponding 4-aryl-3-methyl-2,4,5,7-tetrahydropyrazolo3,4-b]pyridin-6-ones. The structure of 3-methyl-4-(4-nitrophenyl)-2,4,5,7-tetrahydropyrazolo3,4-b]pyridin-6-one was proved by X-ray analysis. |
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