Pyrazole 5-methoxy-4-nitro

Treatment of 4-methoxy-3-nitrocoumarin 23 with hydrazine hydrate and methylhydrazine in ethanol at room temperature for 3 h gave 1,2-dihydro-5-(2-hydroxyphenyl)-4-nitro-3H-pyrazol-3-one 24a and l,2-dihydro-5-(2-hydroxyphenyl)-2-methyl-4-nitro-3H-pyrazol-3-one 24b in 70 and 51% yields, respectively. 

S02-NH-Ar ch3 och3 0 cH3 —< J -N02 co-c6hs c6h, 4 Aryl( Hetaryl) aminosulfonyl-phenytazo]-1-benzoyl-5-meth-yl-3-(4-methyl-phenyl)-pyrazol 4- [A ryl( Hetaryl) aminosulfonyl-phenylazo -5-( 4-methoxy-phenyl) -3- (4-nitro-phenyl)-l-phenyl-... 71-78 68-74 1 2... 

The acylation of a series of pyrazolo[3,4-c]pyridines has been studied.110 Acetic anhydride in refluxing benzene converted S-substituted derivatives to 1-acyl compounds (101 R2 = H), whereas the 7-methoxy derivative afforded the 2-substituted product 102 (R1 = H, R2 = OMe), attributed to peri interaction. In the absence of solvent, however, the latter reaction gave the 1-acyl isomer as the major product. Furthermore, benzoylation of the 5-chloro bicycle furnished a mixture of 101 and 102 (R1 = Cl, R2 = H). However, products benzoylated mainly at N-6 were obtained following introduction of a nitro group into the pyrazole ring. 

The nitration of 3-methoxy-5-methyl-l-phenylpyrazole with nitric acids sulfuric acid at 0°C, followed by 3 h at 50°C, gives 3-methoxy-5-methyl-(4-nitrophenyl) pyrazole (51%), but reaction with mixed acid at 40°C for 24 h gives the 4-nitro-l-(4-nitrophenyl) product (85%). The preparative nitrations (using mixed acid) of the dinitro products are summarized in Table III. No n.m.r. evidence was found for the presence of ortho or meta nitrophenyl isomers. 

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. 

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. 

Propan l-(2-Methoxy-5-methyl-phenyl)-2-nitro-l-nitroso-(dimer) X/l, 74 Propansaure 2-Amino-3-(4-hydroxy-phenyl)- -(carboxy-methylamid) XV/2, 195, 617 3H-Pyrazol 3-Cyclopropyl-4,5-dimethoxycarbonyl-3-methyl-E14, 994 (R2C = N2 4- In) Pyrimidin 2,6-Dimethoxy-5-(2-methoxycarbonyl-ethenyl)-4-methyl- E9b/2, 224f. 

Geht man direkt von 1,3-Dinitro-alkanen aus, werden mit Hydrazin-Hydrat und 1,3-Dinitro-2-phenyl-butan oder 2,4-Dinitro-3-(4-methoxy-phenyl)-pentan 3(5)-Methyl-4-phenyl- (56% Schmp. 140-142°) bzw. 3,5-Dimelhyl-4-(4-methoxy-phenyl)-IH-pyrazol (68% Schmp. 153-155°) erhalten. 1-Nitro-l-alkene cyclisieren thermisch in Dimethylformamid mit D-Ga-lactose-phenylhydrazon2138 ... 

Benzyl-3-methyl-1 H-pyrazol-2-oxid wird mit Trimethyloxoniumtetrafluoroborat (2 h Nitro-methan) am N-Oxid-O-Atom zu l-Benzyl-2-methoxy-3-methyl-pyrazoliumtetrafluoroborat me-thyliert (80% Schmp. 107-109°). Mit 2,2-Dimethyl-propansaure-chlorid und Silbertrifluor-... 

Nebenrcaktionen sind in einigen Fallen Denitrierungen. Als Ausnahme verlauft die Umlagerung von 5-Methyl-1-nitro-1 H-pyrazol (140° Methoxy-benzol) in 93%iger Ausbeute zu 3(5)-Methyl-4-nitro-1 H-pyrazol (doppelte [1,5]-Verschiebung)141. 

Benzylamino-4-nitro- 663 5-Benzylamino-3-phenyl-4-phenylazo- 629 l-Benzyl-4-brom-3-(carboxy-methoxy)-4-mcthyl-5-oxo-4,5-dihydro- 707 l-Benzyl-5-carboxy- 620 l-Benzyl-3-(carboxy-methoxy)-4-methyl- 707 l-Benzyl-3-(l-carboxy-l-methyl-ethoxy)-4-chlor-aus 1 -Bcnzyl-4-chlor-3-hydroxy-1 H-pyrazol/ Natriumhydroxid/2-Hydroxy-l-methyl-1,1,1-trichlor-propan 651... 

Methyl, 3-Phenyl-, 5-Methoxy-, 5- odcr 6-Chlor-, 6-Nitro-l II- (honzo-[c]-pyrazol) sowio einige benzo-kondenaierte Derivate gehen diese Umlagerung nicht ein. 

ClbHi5CI2N3O3, 3-trans-Bis(4-chlorophenyl)-2-cis-nitro-5-oxoperhyd-ropyrazolo[1,2-aIpyrazole, 45B, 277 ClbHi5CI2N3O3, 3-trans-Bis(4-chlorophenyl)-2-trans-nitro-5-oxoper-hydropyrazolo[1,2-a]pyrazole, 45B, 278 ClbHi5N5O, 3-Benzyl-7-methoxy-6-phenylimidazo[1,2-b]-s-tetrazine, 45B, 278... 

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