Molbank 2005, M414

Synthesis of N-Isopropylidene-N’-(3-Methyl-1-Phenyl-1H-Pyrazolo[4,3-e][1,2,4]Triazin-5-yl)-Hydrazine and N-Benzylidene-N’-(3-Methyl-1-Phenyl-1H-Pyrazolo[4,3-e][1,2,4]Triazin-5-yl)-Hydrazine

Mariusz Mojzych

Institute of Chemistry, University of Podlasie,

ul. 3 Maja 54, 08-110 Siedlce, Poland

Received: 23 April 2004 / Accepted: 30 July 2004 / Published: 1 August 2005

Keywords: 1H-pyrazolo[4,3-e][1,2,4]triazine, Schiff bases.

As part of our ongoing research program on bicyclic heteroaromatics chemistry [1-4] we synthesised the title compounds with the goal of performing structure-activity relationship studies.

N-Isopropylidene-N’-(3-methyl-1-phenyl-1H-pyrazolo[4,3-e][1,2,4]triazin-5-yl)-hydrazine (2)

5-Hydrazino-1H-pyrazolo[4,3-e][1,2,4]triazine 1 (120 mg, 0.5 mmol) was dissolved in 20 ml of acetone. The mixture was stirred at room temperature for 10 min. The precipitated solid was filtered off and recrystallized from ethanol to give 2 (126 mg, 0.45 mmol) in 90% yield.

Melting Point: 165 ^ºC.

¹H-NMR (200 MHz, CDCl₃): δ= 2.08 (s, 3H); 2.21 (s, 3H); 2.71 (s, 3H); 7.27-7.36 (m, 1H); 7.49-7.58 (m, 2H); 8.28-8.33 (m, 2H); 8.62 (s, 1H, NH).

¹³C-NMR (50 MHz, CDCl₃): δ= 11.27; 16.53; 25.65; 119.41; 125.99; 129.27; 136.74; 138.73; 141.93; 146.87; 151.65; 158.65.

IR (KBr, cm^-1): 3378; 2997; 1505.

MS (EI, 70eV; m/z, %): 281 (12) [M⁺]; 266 (100); 226 (15); 129 (18); 104 (26); 94 (14); 77 (51).

HR-MS (EI, 70eV): Calcd. for C₁₄H₁₅N₇: 281.13889; Found: 281.13832.

N-Benzylidene-N’-(3-methyl-1-phenyl-1H-pyrazolo[4,3-e][1,2,4]triazin-5-yl)-hydrazine (3)

To a solution of 1 (120 mg, 0.5 mmol) in methanol (30 ml) benzaldehyde (0.1 ml, 1 mmol) and 10% HCl (0.3 ml) were added. The mixture was refluxed for 5 min and then stirred at room temperature for 30 min. The solvent was removed in vacuo and the crude product was recrystallized from dioxane. Yield of 3 is 88% (145 mg, 0.44 mmol).

Melting Point: 283 ^ºC.

¹H-NMR (200 MHz, DMSO): δ= 2.62 (s, 3H); 7.33-7.51 (m, 4H); 7.58-7.65 (m, 2H); 7.72-7.77 (m, 2H); 8.22 (s, 1H); 8.25-8.29 (m, 2H); 12.11 (s, 1H);

IR (KBr, cm^-1): 3220; 1600; 1490; 750; 700.

HR-MS (ESI): Calcd for C₁₈H₁₆N₇: 330.1462; Found: 330.1458.

Elemental Analysis: Calculated for C₁₈H₁₆N₇.0.25H₂O: C, 64.76%; H, 4.64%; N, 29.38%. Found: C, 64.82%, H, 4.68%; N, 29.38%.

References:

1.Rykowski, A.; Mojzych, M.; Karczmarzyk, Z., Heterocycles, 2000, 53, 2175.

2.Karczmarzyk, Z.; Mojzych, M.; Rykowski, A., J. Chem. Cryst., 2000, 30, 423.

3.Mojzych, M.; Rykowski, A., Polish J. Chem., 2003, 77, 1797.

4.Mojzych, M.; Rykowski, A., Heterocycles, 2004, submitted.

Sample Availability: Available from MDPI.