5- Iodo-4-nitro-1,3-dimethylpyrazole

Whereas the condensation of o-iodonitrobenzene with copper acetylides is accompanied by cyclization into isatogens, neither 4-iodo-3-nitro- nor 5-iodo-4-nitro-1,3-dimethylpyrazole gives cyclized products in conditions of acetylide synthesis. Moreover, nitropyrazolylphenylacetylene, as compared with o-nitrotolane, does not undergo thermal, catalytic, or photochemical isomerization to give the fused five-membered rings. 

It is noteworthy that the only deiodinated product (4-nitro-1,3-dimethylpyrazole) was isolated in a 70% yield (86TH1) by cross-coupling phenylacetylene with 5-iodo-4-nitro-l,3-dimethylpyrazole (Scheme 44). 

Interestingly that the //rwmil ration of the pyrazole in the presence of a carboxylic group takes place, whereas 3-iodo-4-nitro-l,5-dimethylpyrazole has also obtained by nitrodecarboxylation of 3-iodo-l,5-dimethylpyrazole-4-carboxylic acid [370] (Scheme 50). 

The proton spectra of 1-substituted 3-nitropyrazoles [296], 5-substituted 3-methyl-l-aryl-4-nitropyrazoles [297, 298], 1,3- and l,5-diphenyl-4-nitropyra-zoles [281], 5-iodo-4-nitro-l,3-dimethylpyrazole [299], l-methyl-3-nitro-4- and l,3-methyl-4-nitro-5-phenylethynylpyrazoles [300], l-methyl-3-nitro-5-methoxy-carbonylpyrazole [301], l-methyl-3-nitro- and l-methyl-5-nitro-4-cyanopyrazoles [302], A-(2,4-dinitrophenyl)nitropyrazoles [303], a- and [3-anomers of 3-nitro-and4-nitropyrazolyl-l-ribonucleosides [304, 305], 3-substituted 1,5-dimethyl- [306] and 5-substituted l,3-dimethyl-4-nitropyrazoles [279], l-acetyl-3-anilino-4-nitro-5-dimethylaminopyrazoles [307], 3-substituted 4-nitro-5-carboxylic acid derivatives [308, 309], 4-nitropyrazolo[4,3-e][l, 4]diazepin-5,8-diones showing antimicrobial activity [310], l-heteryl-4-nitropyrazole derivatives [311], 3-nitro- and 5-nitro-l-methylpyrazole [312], 4-nitro-5-(trimethylsilyl)pyrazole [313], 3-methyl-4-nitro-pyrazol-5-ones [298], and some other nitropyrazoles [248, 314-320] have been examined. 

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