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Short Note

Ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-yl)acetate

by
Thoraya A. Farghaly
and
Sobhi M. Gomha
*
Department of Chemistry, Faculty of Science, University of Cairo, Giza, 12613, Egypt
*
Author to whom correspondence should be addressed.
Molbank 2011, 2011(4), M743; https://doi.org/10.3390/M743
Submission received: 16 August 2011 / Accepted: 13 October 2011 / Published: 10 November 2011
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Abstract

:
Novel ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-yl)acetate (5), was prepared via heating of 5-amino-1,3-diphenyl-4,5-dihydro-4-imino-1H-pyrazolo[3,4-d] pyrimidine (1) and diethyl malonate (2) under reflux. The structure of the synthesized compound was assigned on the basis of its elemental analysis, IR, 1H-NMR and mass spectral data.

Graphical Abstract

Pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine exhibits interesting pharmacological activities such as glycogen synthase kinase-3 inhibitors [1], xanthine oxidase (XO) inhibitors [1] and adenosine receptor antagonists [2,3,4,5,6,7,8,9,10,11]. These observations led us to synthesize a new pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine from 5-amino-1,3-diphenyl-4,5-dihydro-4-imino-1H-pyrazolo[3,4-d]pyrimidine and diethyl malonate.

Results and Discussion

5-Amino-1,3-diphenyl-4,5-dihydro-4-imino-1H-pyrazolo[3,4-d]pyrimidine (1) [12] was allowed to react with diethyl malonate (2) under reflux. The expected product of this reaction was structure 9,11-diphenylpyrazolo[3',4':4,5]pyrimido[1,6-b][1,2,4]triazepin-2,4-dione (3) or 4-ethoxy-9,11-diphenylpyrazolo[3',4':4,5]pyrimido[1,6-b][1,2,4]triazepin-2-one (4) or its isomeric ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-yl)acetate (5) (Scheme 1). MS, 1H NMR, IR and elemental analyses data of the isolated product were in full agreement with the structure 5 not the isomeric structures 3 or 4. The IR spectrum of the isolated product showed bands at 1735 cm−1 characteristic for ester carbonyl group. Its 1H NMR spectrum showed a singlet signal at δ 4.12 for the acyclic CH2 protons, in addition to triplet and quartet signals at δ 1.25 and 4.22 due to the protons of ethyl group.
Synthesis of ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-yl)acetate (5). A mixture of 5-amino-1,3-diphenyl-4-iminopyrazolo[3,4-b]pyrimidine (1) [12] (3.02 g, 10 mmol) and diethyl malonate (2) (2.4 g, 15 mmol) was heated under reflux for 2 h. After cooling, the solid precipitated was collected and crystallized from ethanol/dioxane mixture (1:1).
Yield: 96%; Yellow crystals; m.p. 200–202 °C.
GC-MS m/z (%): 399 (M++ 1, 12), 398 (M+, 50), 326 (43), 256 (4), 127 (8),77 (100), 51 (65).
IR (KBr) vmax cm−1: 1735 (C=O).
1H NMR (300 MHz, CDCl3): δ(ppm) = 1.25 (t, J = 7 Hz, 3H, CH3), 4.12 (s, 2H, CH2), 4.22 (q, J = 7 Hz, 2H, CH2), 7.47-8.70 (m, 10H, Ar-H), 9.69 (s, 1H, pyrimidine-H).
13C NMR (75 MHz, DMSO-d6): 13.99, 34.64, 60.83, 100.62, 122.0, 127.04, 127.31, 128.43, 129.01, 137.73, 138.71, 140.00, 143.83, 145.10, 146.58, 148.14, 161.19, 168.41.
Anal. Calcd. for C22H18N6O2(398.15): C, 66.32; H, 4.55; N, 21.09. Found: C, 66.18; H, 4.42; N, 20.89%.

Supplementary materials

Supplementary File 1Supplementary File 2Supplementary File 3

References and Notes

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Molbank 2011 m743 sch001 550
Scheme 1. Synthesis of the title compound (5).
Scheme 1. Synthesis of the title compound (5).
Molbank 2011 m743 sch001

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MDPI and ACS Style

Farghaly, T.A.; Gomha, S.M. Ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-yl)acetate. Molbank 2011, 2011, M743. https://doi.org/10.3390/M743

AMA Style

Farghaly TA, Gomha SM. Ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-yl)acetate. Molbank. 2011; 2011(4):M743. https://doi.org/10.3390/M743

Chicago/Turabian Style

Farghaly, Thoraya A., and Sobhi M. Gomha. 2011. "Ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-yl)acetate" Molbank 2011, no. 4: M743. https://doi.org/10.3390/M743

APA Style

Farghaly, T. A., & Gomha, S. M. (2011). Ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-yl)acetate. Molbank, 2011(4), M743. https://doi.org/10.3390/M743

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