Indazole 4.6- dinitro

With mixed acid 1-methylpyrazole 2-oxide (268) gives high yields of l-methyl-5-nitropyrazole 2-oxide (269) (B-76MI40402). The form undergoing the reaction is the base, for which first-order kinetics are observed in the Hq range from -5 to -6.5 a dinitro derivative is also formed under slightly different conditions. The reaction of indazole with fuming nitric acid affords a nearly quantitative yield of 5-nitroindazole (Section 4.04.2.3.2(i)). 

Dinitro-naphthalin liefert nach der Elektrolyse bei -0,7 V an Quecksilber letztlich (Benzo-[c,d]-indazol)-N-oxid (32% d.Th.)2 ... 

Thermolysis reactions have also been investigated as methods for preparing pyrazoles. Thermolysis of azido imines 18 led to 2-substituted-4,6-dinitro-2//-indazoles 19 <00S1474>. High temperature intramolecular cyclization of AA-diethyl-A -(4-substituted-2-... 

Dinitro>6>amino, (OaN)a C7HsNa NHa, mw 223-15, N 31.39%. Brn-yel scales, mp—melted with decompn on heating on Pt foil in flame very diff sol in w, easier in boiling AcOH. Was prepd by heating 5,7-dinitro-6-indazolesulfonic acid with ammonia... 

Dinitro-6-nitramino-indazole, (02N)2C7HtN2 -NH(N02), mw 268.15, N 31 34%. Refs to this compd and higher nitrated derivs, which undoubtedly would be expl were not found in... 

Dinitro-6-anilino-indazole, CgHg NH-C7Hs(N02)2N2, mw 299-24, N 23-41% is described in Beil 25,318... 

The nitration of indazoles seems to have been little studied. The nitration of 1-phenylindazole (32) in 86% nitric acid gives 4-nitro-1-phenylindazole (33) but an uncharacterized dinitro derivative is obtained with potassium nitrate in sulfuric acid (36LA285). 

NMR spectra of vicarious /V-alkylation products of 7-nitroinduzoles [672], l-benzylamino-3-nitroindazole [673], 1- and 6-nitroglucosylindazoles [674], l-acetyl-3-chloro-6-nitroindazole [675], the products of methylation and acetylation of 5- and 6-nitroindazoles in various solvents (CDC13, DMSO, acetone) [676], 5-nitro-7-methylindazole [677], 2-substituted 4,6-dinitroindazole [678], several dinitro indazoles [679], 6-nitroindazole derivatives [680], 44 nitrated 1- and 2-methylindazoles having H, Cl, and Br substituents in position 3 [681] have been obtained. II NMR data of some nitroindazoles are presented in a few studies [682-684],... 

This reaction has been used as the key step in an original synthesis of formycin (80CJC2624). By a similar mechanism, via a 3H-indazole, the 2,5-dinitro derivative reacts with secondary amines to afford 3-amino-5-nitroindazoles <80MI40404,8UOC2706, 82PNA4487). 

Ahnlich wird aus 2,4,6-Trinitro-benzaldehyd-(4-ethoxy-phenylimin) 4,6)-Dinitro-2-(4-ethoxy-phenyl)-3-hydroxy-2H-indazol-l-oxid118 [Schmp. 209° (Ethanol)] erhalten. 

Durch Einwirkung von waBriger Kaliumhydroxid-Losung auf 4-[Ethoxycarbonyl-(2-phenyl-hydrazono)-methyl]-l, 3-dinitro-benzol (R = OC2H5) tritt Cyclisierung unter Abspaltung der Nitro-Gruppe zu 3-Carboxy-6-nitro-1 -phenyl-1 H-indazol (R = OH)176, l7X- 57°-571 ein. 

Wird statt des 2,6-Dinitro-benzaldehyds ein 2-Halogen-5-nitro-benzaldehyd bzw. 3-Acyl-4-ha-logen-l-nitro-aren eingesetzt, so fungiert das Halogen-Atom als Abgangsgruppe175,573- 715 und fiihrt ebenfalls zum Indazol z. B. ... 

Ahnlich wie bei der Halogenierung sind auch die Verhaltnisse bei der Nitrierung. Wahrend mit Salpetersaure nur der Benzo-Ring nitriert wird und man zuerst 5-Nitro-, dann 5,7-Dinitro-indazol erhalt, wird in essigsaurer Losung 3-Nitro- (54%) und 3,5-Dinitro-1 H-indazol (20%) gebildet271 272 285. 

Analog werden 1,5-Dinitro-l H- (13%), 3-Brom-l,4-dinitro-lH- (Schmp. 136°) und 3-Brom-l,6-dinitro-lH-indazol (Schmp. 140-142 ) erhalten639. 

Mit Fluor-nitro- und Dinitro-fluor-arenen sowie 2-Chlor-l,3,5-trinitro-benzol gelingt die di-rekte Einfiihrung eines Aryl-Restes im Indazol, wobei ein Gemisch des 1-Aryl-1 H- und des 2-Aryl-2H-indazols erhalten wird275,326. 

Hydroxyindazoles. A soln. of 2-(4-methoxyphenyl)-4-phenyl-4-(2,4,6-trinitro-phenyl)-5(4//)-oxazolone in methanol refluxed for 3 h in the presence of a little /7-TsOH - 4,6-dinitro-3-phenyl-l//-indazol-l-ol. Y 78%. F.e. and 6-nitro-lff-pyrazolo 4,3- pyridin-l-ols from the corresponding dinitropyridyl analogs s. M. D Anello et al., Chem. Ber. 121, 67-73 (1988). 

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