Facile, mild and efficient synthesis of azines using phosphonic dihydrazide

Several bis(N'-arylpropanehydrazonoyl chlorides) were synthesized in good yields from condensation reactions of hydrazonoyl chlorides and phosphonic dihydrazide. Under the conditions employed, none of the expected phosphorylhydrazines were isolated. Nucleophilic substitution of bis(N'-arylpropanehydrazonoyl chlorides) with thiophenol, sodium phenylsulfinate, hydroxyl amine, and piperidine afforded the corresponding azines. Similarly, 1,2-bis(heteroaryl)ethylidene)hydrazines were produced from reaction of phosphonic dihydrazide and heteroaryl methyl ketones. The structures of the products were confirmed by NMR and IR spectral data along with X-ray crystal structure determination and their purities were confirmed by the elemental analyses

Synthesis of novel heterocycles using 1,2,3‐triazole‐4‐carbohydrazides as precursors

Herein, we report the synthesis of various heterocyclic ring systems containing 1,2,3‐triazole from the reactions of acid hydrazides and commercially available reagents, using efficient and simple procedures. Reactions of certain 1,2,3‐triazole‐4‐carbohydrazides and α‐bromoketones in boiling ethanol afforded the corresponding hydrazones rather than the expected triazines. The hydrazones could also be synthesized in 85‐90% yield via an alternative pathway that involved the reaction of 1,2,3‐triazole‐4‐carbohydrazides and 4‐acetyl‐1,2,3‐triazoles in boiling ethanol containing glacial acetic acid. Reaction of one of the 4‐carbohydrazides with carbon disulfide, followed by the reaction with hydrazine hydrate, gave 4H‐1,2,4‐triazole‐3‐thiol in 73% yield, which further reacted with other α‐bromoketones in boiling ethanol to afford 7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazines in 82‐84% yields. Additionally, reactions of certain carbohydrazides with ethyl 2‐cyano‐3,3‐bis(methylthio)acrylate gave 1‐aryl‐1H‐1,2,3‐triazole‐4‐carbohydrazides rather than the expected 1H‐pyrazole‐4‐carboxylates

Fused Imidazopyrazoles: Synthetic Strategies and Medicinal Applications

The current review summarizes the known synthetic routes of fused imidazopyrazoles. This review is classified into two main categories based on the type of annulations, for example, annulation of the imidazole ring onto a pyrazole scaffold or annulation of the pyrazole ring onto an imidazole scaffold. Some medicinal applications of imidazopyrazoles are mentioned

4-(4-Bromophenyl)-2-(3-(4-chlorophenyl)-5-{3-[5-methyl-1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl]-1-phenyl-1H-pyrazol-4-yl}-4,5-dihydro-1H-pyrazol-1-yl)-1,3-thiazole

The asymmetric unit of the title compound, C37H28BrClN8S, comprises one molecule. The molecule consists of two ring systems joined by a C—C bond between the dihydropyrazolyl and pyrazolyl rings of the two extended ring systems. The angles between adjacent ring planes of the tolyl–triazolyl–pyrazolyl–phenyl ring system are 48.2 (1), 12.3 (2) and 22.2 (2)°, respectively, with angles of 19.7 (1), 5.6 (2) and 0.9 (2)° between the rings of the chlorophenyl–thiazolyl–dihydropyrazolyl–bromophenyl set. The pyrazolyl and dihydropyrazolyl rings are inclined at 68.3 (1)° to one another. In the crystal, C—H...Cl interactions form chains of molecules parallel to the b-axis direction

4-(4-Bromophenyl)-2-(3-(4-chlorophenyl)-5-{3-[5-methyl-1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl]-1-phenyl-1H-pyrazol-4-yl}-4,5-dihydro-1H-pyrazol-1-yl)-1,3-thiazole

The asymmetric unit of the title compound, C37H28BrClN8S, comprises one molecule. The molecule consists of two ring systems joined by a C—C bond between the dihydropyrazolyl and pyrazolyl rings of the two extended ring systems. The angles between adjacent ring planes of the tolyl–triazolyl–pyrazolyl–phenyl ring system are 48.2 (1), 12.3 (2) and 22.2 (2)°, respectively, with angles of 19.7 (1), 5.6 (2) and 0.9 (2)° between the rings of the chlorophenyl–thiazolyl–dihydropyrazolyl–bromophenyl set. The pyrazolyl and dihydropyrazolyl rings are inclined at 68.3 (1)° to one another. In the crystal, C—H...Cl interactions form chains of molecules parallel to the b-axis direction

4-(4-Bromophenyl)-2-(3-(4-bromophenyl)-5-{3-[5-methyl-1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl]-1-phenyl-1H-pyrazol-4-yl}-4,5-dihydro-1H-pyrazol-1-yl)-1,3-thiazole

In the title compound, C37H28Br2N8S, the dihedral angles between the planes of tolyl–triazolyl–pyrazolyl–phenyl rings are 47.5 (1), 11.4 (2) and 22.4 (2)°, respectively, and the angles between the bromophenyl–thiazolyl–dihydropyrazolyl–bromophenyl rings are 16.0 (2), 5.1 (2) and 0.8 (2)°, respectively. The dihedral angle between the planes of the pyrazolyl and dihydropyrazolyl rings is 67.7 (1)°. In the crystal, weak C—H...Br interactions form chains of molecules propagating in the [010] direction

(E)-1-[5-Methyl-1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl]-3-(4-nitrophenyl)prop-2-en-1-one

The title compound, C19H16N4O3, crystallizes with two molecules (A and B) in the asymmetric unit. In molecule A, the dihedral angles between the triazole ring and the toluyl and nitrobenzene rings are 62.68 (16) and 10.77 (15)°, respectively. The corresponding data for molecule B are 68.61 (17) and 15.59 (15)°, respectively. In the crystal, the B molecules are linked by C—H...N hydrogen bonds to generate [001] chains. Weak C—H...π(benzene) and N—O...π(triazole) contacts are also present

5-Methyl-N'-(5-methyl-1-phenyl-1H-1,2,3-triazole-4-carbonyl)-1-phenyl-1H-1,2,3-triazole-4-carbohydrazide

The asymmetric unit of the title compound, C20H18N8O2, comprises one complete molecule and a half molecule completed by crystallographic twofold symmetry leading to Z = 12. The dihedral angles between the planes of the linked phenyl and methyltriazolyl groups are 69.48 (5) and 44.85 (9)° for the first molecule and 42.88 (9)° for the second. The conformations of the diformyl hydrazyl groups of the molecules are similar as indicated by C—N—N—C torsion angles of −83.4 (2) and −86.4 (3)°. In the crystal, neighbouring molecules are linked by pairs of N—H...O hydrogen bonds to form independent columns propagating parallel to the c-axis direction

2-(5-Methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-5-phenyl-1,3,4-oxadiazole

The asymmetric unit of the title compound, C17H13N5O, comprises four independent molecules (A–D). The respective interplanar angles between the phenyl/oxadiazole/methyltriazole/phenyl rings for the four independent molecules are A 8.8 (2), 13.0 (2), 22.5 (2)°; B 6.3 (2), 8.9 (2), 29.0 (1)°; C 4.0 (2), 10.0 (2), 24.5 (2)°; D 3.5 (2), 10.1 (2), 27.2 (2)°. In the crystal, molecules form two separate stacks parallel to the b-axis direction: one consists of A and D molecules, and the other of B and C molecules. Aromatic π–π stacking is observed within each stack, with the shortest centroid–centroid separation being 3.552 (2) Å

1-{2-Anilino-4-methyl-5-[5-methyl-1-(4-methylphenyl)-1H-1,2,3-triazole-4-carbonyl]thiophen-3-yl}ethanone

In the title compound, C24H22N4O2S, the dihedral angle between the triazole and thiophene rings is 4.83 (14)°. The dihedral angles between the triazole and tolyl rings and between the thiophene and phenyl rings are 48.42 (16) and 9.23 (13)°, respectively. An intramolecular N—H...O hydrogen bond closes an S(6) loop. In the crystal, molecules are stacked parallel to the a-axis direction with weak π–π interactions between adjacent thiophenyl and triazolyl groups within the stack [centroid–centroid separation = 3.9811 (16) Å]