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(E)-Ethyl 3-(Dimethylamino)-2-(7,9-diphenyl-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-2-yl)acrylate

Department of Chemistry, Faculty of Science, University of Cairo, Giza, 12613, Egypt
*
Author to whom correspondence should be addressed.
Molbank 2011, 2011(4), M746; https://doi.org/10.3390/M746
Received: 30 November 2011 / Accepted: 13 December 2011 / Published: 20 December 2011

Abstract

Novel (E)-ethyl 3-(dimethylamino)-2-(7,9-diphenyl-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-2-yl)acrylate (3A), was prepared via condensation of ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-yl)acetate (1) and dimethylformamide-dimethylacetal under reflux. The structure of the synthesized compound was assigned on the basis of elemental analysis, IR, 1H NMR and mass spectral data.
Keywords: pyrazolo-triazolo-pyrimidine; enaminone pyrazolo-triazolo-pyrimidine; enaminone
Enaminones are poly-dentate reagents that have been utilized extensively in this decade as building blocks in organic synthesis [1,2,3,4,5]. Many reports indicated that the presence of a basic side chain like the N,N-dialkylaminoalkyl group enhances the drugs’ DNA affinity [6] and their anticancer activity, e.g., against the human breast cancer cell line, MCF-7 [7]. In addition, pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidines have been used as potent and selective adenosine A2A receptor antagonists [8,9,10,11,12,13,14,15]. This finding prompted us to condense ethyl (1,3-diphenyl-1H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyri­midin-5-yl)acetate (1) [16] with dimethylformamide-dimethylacetal (DMF-DMA) to obtain the title compound 3A (Scheme 1). Elemental analyses and spectral data were in complete accordance with the assigned structure 3. For example, the 1H NMR spectrum of compound 3 revealed two singlet signals at δ 3.30 and 7.77 ppm characteristic for N,N-dimethylamino and the exocyclic C=CH protons, respectively [1]. The value of the exocyclic C=CH proton signal at δ 7.77 ppm correlated with the E-isomer (3A), while the Z-isomer 3B of an analogous structure was reported to appear at δ 6.9 ppm [17]. Thus, we have successfully synthesized a new enaminone in good yield which can be used as a building blocks for heterocyclic ring systems in organic synthesis.
Synthesis of (E)-ethyl 3-(dimethylamino)-2-(7,9-diphenyl-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-2-yl)acrylate (3)
A mixture of 1 (4.3 g, 10 mmol) and dimethylformamide-dimethylacetal (10 mL) was refluxed for 20 min. After cooling, the precipitate was collected by filtration, washed with methanol and crystallized from dioxane.
Yield: 92%; pale yellow crystals; m.p. 240 °C.
GC-MS m/z (%): 454 (M++ 1, 4), 453 (M+, 13), 380 (11), 336 (12), 167 (23),77 (100), 51 (48).
IR (KBr) vmax cm−1: 1624 (C=O).
1H NMR (Bruker, 300 MHz, CDCl3): δ (ppm) = 1.13 (t, J = 7.0 Hz, 3H, CH3), 3.30 (s, 6H, 2 CH3), 4.07 (q, J = 7.0 Hz, 2H, CH2), 7.47-8.7 (m, 10H, Ar-H), 7.77 (s, 1H, =CH), 9.68 (s, 1H, pyrimidine-H).
Anal. Calcd. for C25H23N7O2 (453.19): C, 66.21; H, 5.11; N, 21.62. Found: C, 66.11; H, 5.01; N, 21.39%.

Supplementary materials

Supplementary File 1Supplementary File 2Supplementary File 3

References

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Scheme 1. Synthesis of the title compound (3A).
Scheme 1. Synthesis of the title compound (3A).
Molbank 2011 m746 sch001
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