4-Phenylethynylpyrazole-3 -carboxylic

In the heterocyclization reactions of 4-acetylenyl-l-methylpyrazole-3-carbox-ylic acids and 4-acetylenyl-l-methylpyrazole-5-carboxylic acids the behavior is the same. Isomeric l-methyl-4-phenylethynylpyrazole-3-carboxylic acid forms... 

Intramolecular addition of the amide group to the triple bond in pyrazoles is more difficult, and results in closure of the 5-lactam rather than the y-lactam ring. The reaction time of the 4-phenylethynylpyrazole-3-carboxylic acid amide under the same conditions is extended to 42 h (Scheme 129) (Table XXVII). The cyclization of l-methyl-4-phenylethynyl-l//-pyrazole-3-carboxylic acid amide, in which the acetylene substituent is located in the 7r-electron-rich position of the heterocycle, is the only one complete after 107 h (Scheme 130) (90IZV2089). 

JA742). However, the heterocyclization of 4-phenylethynylpyrazole-3- and 4-phenylethynylpyrazole-5-carboxylic acid in alcohol or acetonitrile solutions in the presence of AgNOs caused, once again, the closure of the six-membered lactones. 

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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