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In the title molecule, C13H16N4O2, the fused triazolopyrimidine ring system is planar. In the crystal, inversion-related C—H...O hydrogen bonds form dimers that are linked into chains extending along the a-axis direction by inversion-related C—H...π(ring) interactions.

In the title compound, C14H11N3O2, the indazole portion is planar to within 0.022 (2) Å and subtends a dihedral angle of 65.87 (7)° with the pendant benzene ring. In the crystal, oblique stacks of molecules extending along the a-axis direction are generated by π–π stacking interactions between the five- and six-membered rings [centroid–centroid separation = 3.6743 (19) Å] and the stacks are cross-linked by C—H...O hydrogen bonds.

In the title compound, C19H16N4, the pyrazolopyrimidine unit is slightly twisted. A combination of π-stacking and offset π-stacking interactions forms columns along theb-axis direction.

The asymmetric unit of the title compound, C9H6ClN3O3, contains one full molecule in a general position and a half molcule sitting on a crystallographic mirror plane. In the crystal, molecules form stacks extending along theb-axis direction through a combination of offset π–π stacking between indazole units and C—Cl...π(ring) interactions with the six-membered rings of the same units. Elaboration of the C—Cl...π(ring) interactions along thea-axis direction forms slabs of molecules parallel to [001]. The stacks are joined by a combination of C—H...O and C—H...N hydrogen bonds.

In the title molecule, C9H7N3O3, the indazole moiety is essentially planar and the mean plane of the acetyl substituent is twisted by 5.3 (1)° from its plane. In the crystal, weak C—H...O and C—H...N hydrogen bonds form layers parallel to (102), which are associated through π-stacking interactions to form a three-dimensional network. The structure was refined as a two-component twin.

In the title compound, C9H8ClN3O2, the orientation of the ethyl substituent is partly determined by an intramolecular C—H...Cl hydrogen bond. The indazole moiety is slightly folded with an angle of 0.70 (8)° between the five- and six-membered rings. In the crystal, molecules pack in layers parallel to [100] through C—H...π(ring) and N...;O...π(ring) interactions.

In the title compound, C10H10ClN3O3, the side chain is oriented nearly perpendicular to the mean plane of the indazole ring system. In the crystal, complementary sets of O—H...N and C—H...O hydrogen bonds form chains of molecules stacked along thea-axis direction

The 5-nitro-1H-indazol-1-yl moiety of the title compound, C15H10BrN3O3, is approximately planar, with the largest deviation from the mean plane being 0.079 (3) Å. The fused-ring system is virtually perpendicular to the mean plane through the 1-phenylethanone group, making a dihedral angle of 89.7 (2)°. In the crystal, pairs of molecules form inversion dimersviaBr...O interactions [3.211 (2) Å]. The dimers are connected by C—H...O and C—H...N non-classical hydrogen bonds, in addition to π–π interactions [intercentroid distance = 3.6411 (12) Å], forming a three-dimensional network.

The asymmetric unit of the title compound, C11H11N3O4, comprises two independent molecules, both of which display positional disorder of their ethyl chains in 0.868 (4):0.132 (4) and 0.839 (4):0.161 (4) ratios. The packing is directed by a combination of C—H...O hydrogen bonds and N—O...π interactions between nitro groups and the aromatic rings.

The crystal of the title salt hydrate, C2H6N5+·C7H4NO4−·2H2O, is built up from a 3,5-diamino-4H-1,2,4-triazol-1-ium cation linked to a 4-nitrobenzoate anion and to two water molecules through strong hydrogen bonds. The triazolyl ring is virtually planar, with the maximum deviation from the mean plane being 0.003 (1) Å. Small twists are noted in the anion with the dihedral angles between the ring and carboxylate and nitro groups being 7.82 (13) and 9.10 (15)°, respectively. In the crystal, molecules are linked by N—H...O, N—H...N, O—H...O and C—H...O interactions, forming layers parallel to (-101). The sheets are linked by O—H...O hydrogen bonds and π–π interactions between triazole and benzene rings [inter-centroid separation = 3.4967 (8) Å] to form a three-dimensional structure.

The asymmetric unit of the title compound, C17H14N2O3, consists of two independent molecules having distinctly different conformations. The components of the asymmetric unit are connected by an O—H...N hydrogen bond, with additional O—H...N hydrogen bonds connecting this assemblage into chains running parallel to thebaxis. Intermolecular C—H...π(ring) interactions are also present.

In the title compound, C15H14N2O2, the seven-membered benzodiazepine ring adopts a twist-boat conformation and the two aromatic rings are inclined to one another by 81.06 (15)°. In the crystal, molecules are linked by N—H...O hydrogen bonds, forming chains propagating along the [10-1] direction. The chains are linked by C—H...O hydrogen bonds, forming sheets parallel to theacplane. Within the sheets, there are N—H...π interactions present, and C—H...π interactions link the sheets to form a three-dimensional structure.

The title compound, C14H11N3O2, crystallizes with two molecules in the asymmetric unit. The indazole ring system and the nitro group are nearly coplanar, with the largest deviations from the mean plane being 0.070 (4) Å in one molecule and 0.022 (3) Å in the second. The dihedral angle between the mean plane through the phenyl ring and the mean plane of the indazole ring system is of 23.24 (18)° in the first molecule and 26.87 (18)° in the second. In the crystal, molecules are linked by two C—H...O hydrogen bonds, forming linear zigzag tapes running along thec-axis direction, and by π–π stacking of molecules along thebaxis, generating a three-dimensional structure.

In the title molecule, C9H9N3O2, the nitro substituent is twisted by 4.0 (2)° out of the plane of the indazolyl moiety; the ethyl group is perpendicular to the indazolyl plane, with the N—N—C—C torsion angle being 101.4 (2)°. In the molecular packing, C—H...O hydrogen bonds lead to supramolecular chains along [001]. Globally, molecules assemble into layers in thebcplane. π–π interactions between five- and six-membered rings consolidate the three-dimensional packing [inter-centroid distance = 3.591 (1) Å]. The sample was refined as an inversion twin.

The synthesis of new 7-alkoxy-4-amino-protected indazole and 4-amino-protected indazole derivatives by the reduction of the nitro group of 4-nitroindazoles using anhydrous stannous chloride in different alcohols is described.

Condensation of β-Ketoesters with 7-aminoindazoles have been examinated. The structure of pyrazolo [1,5,4-ef] benzodiazepin -6- ones, obtained from ethylacetylacetate have been established by mass spectrometry and by 1H NMR in presence of Europium (fod)3.

Ethyl-2-bromo-2-(2′-oxo-3′-quinoxalinyl) acetates 3-4 react with potassium thiocyanate in dimethylformamide, at room temperature, afforded 10-ethoxycarbonyl-2-imino-8-oxo thiazolo [3,4-a] quinoxalines 7-8.

The mononitration of some 2-Alkyl-5(6)chloro-(or methyl-) benzimidazoles was carried out because the chemical literature results were ambiguous. Our work has shown that the nitro group was introduced in 6 (or 5) position.

The synthesis of new pyrazolo [1,5,4-ef] triazolo [3,4-a] [1,5] benzodiazepines have been described. Hydrazinolysis of pyrazolobenzodiazepinethiones leads to 7-pyrazolylamino indazole.

New N-(1H-7-indazolyl)-pyridinones have been prepared by the condensation of 2-pyrone derivatives with 7-aminoindazole in the presence of acid medium. They have been characterized by means of 1H and 13C NMR, IR, and mass spectroscopy. The structure of the compounds and the mechanism of their formation are reported.

7-Alkoxy-4-amino-protected indazole and 4-amino-protected indazole derivatives are obtained by reduction of the nitro group in 4-nitroindazoles using anhydrous stannous chloride in different alcohols.

New N-(1H-7-indazolyl)-pyridinones have been prepared by the condensation of 2-pyrone derivatives with 7-aminoindazole in the presence of acid medium. They have been characterized by means of 1H and 13C NMR, IR, and mass spectroscopy. The structure of the compounds and the mechanism of their formation are reported.

The condensation of β-dicarbonyl compounds with 5,6-diaminoindazole in hot butanol leads to pyrazolo[4,5-f]benzimidazole, 5(1-phenylvinyl)pyrazolo[4,5-f]benzimidazolone-6 and 4-phenyl pyrazolo[3,4-h][1,5]benzodiazepin-2-one.

Resume On decrit la preparation de differents aminoindazoles par photosubstitution nucleophile aromatique de nitroindazoles par les amines. Les groupements amino, methylamino, dimethylamino et diethylamino sont ainsi introduits en position 3, 4, 5 ou 7 L'irradiation en presence d'ethanol a permis d'obtenir des ethoxyindazoles seulement dans quatre cas. Deux reactions de demethylation ont ete observees l'une concerne la formation de derives methylamino par action de la dimethylamine; l'autre la formation d'indazoles NH par irradiation en presence de dimethylamine.

Condensation of 7-aminoindazoles 1 and 2 with acetylacetone, followed by reductive cyclisation, leads to a mixture of diastereoisomeric 4,6 dimethyl-4,5,6,7-tetrahydropyrazolo 1,5,4-ef benzodiazepines in a 9/1 ratio.