Pyrazole 3.5- dimethyl-4-nitro

Azido-2,2-dimethyl-8-oxo-E16b, 723 (CH - C-N3) lH-Pyrazol 4-Nitro-3(5)-piperidino-E8b, 598 (N02 - NR2) Pyrimidin 5-Ethoxycarbonyl-2-hydrazino-4-methyl- El 6a, 771 (SR - NH-NH2) lH-Tetrazol l-(l-Carboxy-2-methyl-... 

It is known that the ability of nitrotolane to cyclize depends on electronic factors (69MI2) hence l,3-dimethyl-4-nitro-5-phenylethynylpyrazole, whose acetylene group is in the most electron-accepting position of the pyrazole ring, i.e., favorable for nucleophilic addition, was introduced into the reaction of cyclization. Thus,... 

Of the many substituted and functionalized alkenes that have been combined with diazo dipoles to give A -pyrazolines or products derived from them (i.e., A -pyrazolines, pyrazoles, cyclopropanes), only a selection will be mentioned. These include ot-alkylidene-cycloalkanones (62), -flavanones, -thioflavanones, -chroma-nones, and thiochromanones (63,64) a-arylidene-indanones and -indolones (65) diarylideneacetones (66) l-benzopyran-2(77)-ones (coumarins) (67,68) 4-nitro-1,2-oxazoles (69) 2-alkylidene-2-cyanoacetates (70) dimethyl 2,3-dicyanofuma-rate (71) tetracyanoethylene (72) tetraethyl ethylenetetracarboxylate (72) 1,4-quinones (35,73-75) 2-X-l,l,l-trifluoro-2-propene [X = Br, (76), SPh, SOPh, S02Ph (77)] nitroalkenes (78) including sugar nitroalkenes (79) 1-diethoxyphos-phoryl-1-alkenyl-sulfoxides (80) methyl 2-(acetylamino)cinnamate and -acrylate... 

Dimethyl-A-nitro-l-(A-n itro-phenyl)-3 pyrazol n-5-one, AT19... 

Chloro-l,3-dimethyl-4-nitro-l H-pyrazole, 1858 Chlorodimethylphosphine, 0895 /V-Chloro-4,5-dimethyltriazole, 1486... 

Carbamoyl-2-nitroacetonitrile, 1113 5-Chloro-1,3-dimethyl-4-nitro-1 //-pyrazole, 1858 Mercury(II) 5-nitrotetrazolide, 0977... 

In nitric acid sulfuric acid, 3-methyl-1-phenylpyrazole yields the l-(4-nitrophenyl) derivative (96%), and 5-methyl-1-phenylpyrazole the l-(4-nitro-phenyl) derivative (98%). l-(2-Methylphenyl)- and 3,5-dimethyl-1-phenylpyrazole give low yields (up to 33%) of the 4-nitrophenyl products, but l-(2,6-dimethylphenyl) pyrazole gives l-(2,6-dimethyl-3-nitrophenyl) pyrazole (92%). The l-methyl-2-phenyl and 5-methyl-1-phenylpyrazolium cations are markedly less reactive than the 1-phenylpyrazolium cation, presumably because of steric hindrance to coplanarity of the rings. 

Nitration in acetic anhydride of 3-methyl-l-phenylpyrazole yields the 4-nitro product. 5-Methyl-1-phenylpyrazole gives a mixture of 5-methyl-3-nitro (75%) and 5-methyl-4-nitro-1-phenylpyrazole (25%). 3,5-Dimethyl-, l-(2-methylphenyl)-, and l-(2,6-dimethylphenyl)pyrazole each give the 4-nitro products in 42 and 65% and in unspecified yield, respectively [72JCS(P2)1654]. 

In the nitration of methylphenylpyrazoles, Parrini [57AC(R)929] showed that a mixture of nitric and sulfuric acids leads to nitration first in the para position of the phenyl ring and second in the 4-position of the pyrazole ring. 4-Nitro-(4-nitrophenyl) derivatives were obtained from 3,5-dimethyl-1-phenylpyrazole and 3-methyl-5-phenylpyrazole. 

The results of Katritzky and co-workers [74JCS(P2)382], who carried out an extended study of such systems, are shown in Fig. 10. These indicate that all six compounds studied reacted as the conjugate acid at high acidity. Three compounds also reacted as the conjugate acid at low acidity [3-methyl-4-nitro-l-phenylpyrazolin-5-one, 3-methyl-5-methoxy-4-nitro-l-phenyl pyrazole, and 3-methyl-5-methoxy-l-(4-nitrophenyl) pyr-azole]. The other three compounds [2,3-dimethyl-4-nitro-l-phenylpyraz-olin-5-one, 3-methyl-1-(4-nitrophenyl) pyrazolin-5-one, and 2,3-dimethyl-1-(4-nitrophenyl) pyrazolin-5-one] reacted as free bases at low acidity. 

Ligands in complexes I. = tetrathiafulvalenium, L2 = H2NCOC6H4NH3-2, L3 = 2-H2NC5H4NH, L4 = 2,6-diacetylpyridine-bis(2-furoylhydrazone)dimethyltin, L5 =N,N -dimethyl-5-nitro-2,2/-bi-imidazol-3/-ium, L6 = cytosinium, L7 = 8-methylaminoquinolinium, L8 = iV-(4-hydroxybenzylidene)-4-methoxyaniline, L9 = 8-meth-oxyquinolinium, 1.19 = (3-MePz)3SnBuCl2, T = thiamine, Pz = Pyrazole. cCentrosymmetric anion. 

Dichloroacetamido)-l-methyl-5-nitroimidazole undergoes a 1,3-dipolar cycloaddition reaction with diazomethane to give (dichloroacetimino)tetrahydroimidazo[4,5-c]pyrazoles in about 10% each (Scheme 5). The failure to observe cycloaddition with l,2-dimethyl-5-nitroimidazole underlines the role of the N- methylated imidazole intermediate (184), a typical non-aromatic a, j6-unsaturated nitro compound acting as a dipolarophile (80TL4757). 

Derivatives of pyrazole containing a nitro group at position 3 or 5 were obtained in this way [393 100], Nevertheless, the diazotiation of 3,5-dimethyl-4-aminopyra-zole does not lead to the formation of nitro derivatives [398],... 

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. 

Mass spectrometry has been used for the structural determination of isomeric I -methyl-3(5)-nitro-4-pyrazolcarbonitriles [302], l,5-dimethyl-3,4-dinitropyrazole [279], 4,4-dinitro-l,l-methylenedipyrazole [1291], 3-amino-5-bcnzylamino-4-nitro-yrazole [317], amino derivatives of 4-nitropyrazole [1292], antibacterial compounds 3-(3-mcthyl-4-nitro- lf/-pyrazole-5-yl)- and 3-(3-methyl-4-nitro-l-alkylpyrazole-5-yl)-5-methyl-4-nitroisoxazoles [500], some l-heteroaryl-4-nitropyrazoles [311]. 

Propansaure 3-(l-Nitro-cyclohexyl)- -nitril E5, 1518 (Ar —N02 + H2C = CH-CN) lH-Pyrazol 3,5-Dimethyl-l-(ethoxycarbonyl-methyl)- E8b,... 

DIMETHYL-N-(2-METHYLPHENYL)-4-NITRO-lH-PYRAZOLE-l-ACETAMIDE see DSQ810... 

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