Indazole 7-nitro-2-phenyl

From UV studies of 4-phenyl-, 4-nitro- and 4-nitroso-pyrazoles, Habraken et al. (67RTC1249,72JHC939) conclude that the 4-pyrazolyl group acts as an electron-donating group. UV spectra of pairs of 1-aryl- and 2-aryl-indazoles and their utility in the determination of isomeric structures are discussed in (67BSF2619) many other UV data on indazole derivatives can be found in (71PMH(3)67). 

Studies of the alkylation of indazoles (67HC(22)1) have been updated by Nunn (73JCS(PD2371) and Palmer (75JCS(P1)1695). The ratio of methylation at positions 1 and 2 is relatively sensitive to the steric effect of substituents at positions 3 and 7 as shown by the results obtained in basic medium for unsubstituted indazole (55 45) and its 3-phenyl (74 26) and7-nitro derivatives (29 71). 

Anthranil, 7-nitro-synthesis, 6, 407 Anthranil, 3-phenyl-thermolysis, S, 91 Anthranilonitriles indazoles from, S, 274 Anthranils... 

The diazotization of 2-alkylaminoanilines containing the nitro group in the phenyl ring leads to 3-substituted indazoles (Scheme 2.24) [11, 17, 282, 291, 292],... 

The molecule of 2-(3,5-di-ferf-butyl-4-hydroxyphenyl)-5-nitroindazole in the crystal is almost planar dihedral angles between the plane of the nitro group, phenyl substituent, and indazole system are 4.5(8) and 2.5(8)°. The C5-N02 bond length is 1.46(1)A [182],... 

Cyan-4-nitro-phenyl)- X/2, 244 (4-Cyan-2-nitro-phenyl)- X/2, 248 lH-Indazol... 

NR - NHj/ RONa) lH-Benzotriazol 1-Ethoxycarbonyl-E4, 155 (Cl - OC2H5) Essigsaure Azido-phenyl- -me-thylester E5, 668 (OH - OR) lmidazol 2-(3-Nitro-phenyl)-4,5-dihydro- E16d, 286 (Nitrierung) IH-Indazol 3-Methylaminocarbony-loxy- E8b, 835 (OH > O CO-NH-R)... 

H-Indazol-l -oxide sind durch Umsetzung von 2-Acyl-l-nitro-arenen, z. B. 2-Nitro-benzal-dehyden718 oder 2-Nitro-phenyl-glyoxylsaure-nitril718,719, mit Aminen zuganglich (s.a. Bd. X/ 3, S. 767). 

Cyan-2-phenyl-2H-indazol-l-oxid71,) Man lost 5 g (0,028 mol) 2-Nitro-phenyl-glyoxylsaurc-nitril in 5 ml Ethanol, gibt 3g (0,03 mol) Anilin und 0,01 g Natriumacetat zu und laBt 3d bei 20 stehen. Dabei kri-stallisiert das Reaktionsprodukt aus und wild nach dem Absaugen mehrmals aus Ethanol umkristallisiert Ausbeute 3,5 g (54%) Schmp. 190c (Ethanol) (farblose Prismen). 

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. 

Mtro-l-phenyl-lH-indazol176 Im Schwertkolben werden 14,15 g (0,05 mol) 3-Carboxy-6-nitro-l-phenyl-lH-indazol auf 280° bis zur Beendigung der Gasentwicklung erhitzt und dann bei 225" i.Hochvak. destilliert Ausbeute 10,1 g (84%) Schmp. J20 (Methanol/Wasser) (gelbliche Nadcln). 

Cyan-4-nitro-phenyl)-2H-indazol cyclisiert beim Erhitzen mit konzentrierter Schwefelsau-re zu II-Imino-9-nitro-l 1 H-[Pg.843]

Bei der Photooxidation von 3,7-Dimethyl-l-(4-nitro-phenyl)-lH-indazol wird neben dem als Hauptprodukt (15%) isolierten 7-Formyl-3-methyl-l-(4-nitro-phenyl)-l H-indazol) in geringer Menge 2-Methyl-9-nilro-6H-(1,5-benzoxazepino[3,4,5-h,i]indazol)1> 9 [1,5% Schmp. 233-235° (Ethanol)] isoliert ... 

Bei der Oxidation von 2-(4-Nitro-phenyl)-2H-indazol mit Chrom(VI)-oxid wird unter Ringofi-nung des Heterocyclus 2-f4-Nitro-phenyla ol-henzocsliurei26 (82% Schmp. 175-176°) gebil-det ... 

Methyl-l-(4-nitro-phenyl)-l,5-dihydro- 788 1 lH-... 

The VNS is the reaction of choice for incorporation of a-sulfonylalkyl substituents into nitroarenes and their heteroanalogues. Particularly accessible and useful are nitroarylmethyl phenyl sulfones and their heteroanalogues that are efficiently produced in the VNS reactions of carbanions of chloromethyl aryl sulfones with a great variety of nitroarenes and nitroheteroarenes. Nitro derivatives of heterocycles, such as pyrrole [54,55], furan [54], thiophene [54], imidazole [106, 112, 113], pyrazole [114], pyridine [57], indole [115], indazole [116, 117], benzimidazole [118], benzotriazole [119], benzofuroxan [120], quinoline [121], and porphyrins [122, 123], have been shown to enter this reaction. 

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). 

Nitn>-t-phenyl-indMol 28 1 34. 4-Nitro-2-phenyl-indazol 28 1 34. x-Nitro-[2-phenyl-mdaail] vom Schmelz ... 

Nitro-oinnamoyl]-indazol 23II134. 4(oder 5)-[2-Nitro-phenyl]-l-benzoyl-imid ... 

Incorporation of a fluorine at C-3 can be achieved by treatment of a preformed 3H)-indazole with electrophilic fluorinating reagents. In the context of a medicinal chemistry programme, scientists at GSK carried out the fluorination of 4-nitro-6-bromo-(7//)-mdazole (120) with Selectfluor in a mixture of acetonitrile and acetic acid (Scheme 39). Best yields (64 %) were observed when the reaction mixture was submitted to microwave irradiation [65]. The scope of this synthetic transformation is somewhat limited, since the regioselectivity is controlled by the presence of two electron withdrawing groups on the phenyl ring. 

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