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6-Chloro-2-hydroxy-2-trifluoromethyl-2H-chromene-3-carboxylic acid (5-allylsulfanyl-[1,3,4]thiadiazol-2-yl)-amide

Molbank 2014, 2014(3), M831; https://doi.org/10.3390/M831

Short Note
3-Cyano-4,6-diphenyl-2-(phenethylamino)pyridine
1
School of Chemistry, University College of Science, University of Tehran, Tehran, 13145-143, Iran
2
Pharmaceutical and Cosmetic Research Center, University of Tehran Research Institute, (PCRC), Tehran, 14155-6455, Iran
3
Department of Medicinal Chemistry and Radiopharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, 14176, Iran
4
Department of Chemistry, University of Malaya, Kuala Lumpur, 50603, Malaysia
5
Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 80203, Saudi Arabia
*
Author to whom correspondence should be addressed.
Received: 15 April 2014 / Accepted: 17 July 2014 / Published: 6 August 2014

Abstract

:
Novel synthesis of a 2-amino-3-cyano-2,6-diphenyl pyridine by a one-pot multi-component reaction of 1,3-diphenylpropane-1,3-dione, malononitrile and phenethylamine in the presence of N-hydroxybenzamide and zinc chloride has been reported. The structure of the synthesized compound was assigned on the basis of its elemental analysis, 1H-NMR, 13C-NMR, IR and mass spectral data. X-ray structure analysis confirmed unambiguously the proposed structure. The photophysical properties (λAbs., λFlu.) in CH3OH, CH3CN, CH2Cl2 and the emission spectrum of the new compound in solution and in the solid state are reported.
Keywords:
2-amino-3-cyano-4,6-diarylpyridine; fluorescence; multi-component reaction; ZnCl2; N-hydroxybenzamide; malononitrile
The optoelectronic devices such as optical fibers, switches, tunable lasers and amplifiers, modulators with various applications need compounds emitting in the blue spectral region [1]. So developing a procedure for the synthesis of thermally stable, highly fluorescent materials can be urgently interesting for technology upgrading. There are some reports on using the fluorescent compounds in biochemical and medical research [2]. 2-Aminopyridine derivatives are of great importance due to their biological activities such as cardioprotective [3], antibacterial [4], antioxidant [5], anti-inflammatory [6] and anti-HIV [7]. Sulfapyridine, an example which contains 2-aminopyridine moiety, is an old marked antibacterial drug. Therefore designing new procedures to synthesize 2-aminopyridine derivatives has attracted a lot of interest. Literature shows some reports on the synthesis of 2-amino-3-cyano-4,6-dialkylpyridines but there are few reports on diaryl ones [8,9,10,11]. Recently we have reported the synthesis of 2-amino-3-cyano-4,6-dialkyl pyridines by the one-pot multi-component reaction of 2,4-pentanedione, malononitrile and primary or secondary amines in the presence of N-hydroxy benzamide or p-toluenesulfonic acid as the acidic catalyst [12]. In continuation of our research on the synthesis of fluorescent compounds [12,13,14], we herein report the synthesis of 3-cyano-4,6-diphenyl-2-(phenethylamino) pyridine using N-hydroxybenzamide and ZnCl2 as an organic acid and Lewis acid catalysts respectively (Scheme 1).
Structure 3 was assigned on the basis of its elemental analysis, 1H-NMR, 13C-NMR, IR and mass spectral data. The light yellow crystals of 3 were obtained by crystallization from ethyl acetate/n-hexane: 1/3 and its X-ray structure was determined to confirm unambiguously its structure. [15] (Figure 1).
Compound 3 has shown fluorescence activity in the blue region in solution and solid phase. The photophysical data for this compound including λAbs. (nm), λFlu. (nm) have been measured for 0.00002 M solutions in CH3OH, CH3CN and CH2Cl2 (Table 1). The fluorescence emission spectrum of compound 3 solutions in CH2Cl2, CH3CN and CH3OH is shown in Figure 2.
Figure 3 shows photographs of compound 3 solutions in CH2Cl2, CH3CN and CH3OH (a): under visible light and (b): under a UV lamp with λ = 366 nm (Philips TL8W/08F8T5/BLC).
The emission spectrum of compound 3 has been determined. The sample is prepared as the following: a solution of compound 3 (0.5 mL) in CHCl3 (10 −8 mol L−1) was first coated on a quartz glass sheet and dried at room temperature, then placed in a 1 cm length quartz cell. The excitation and emission slits were adjusted on 3 nm. The fluorescence emission intensity of compound 3 after excitation in 300 nm is shown in Figure 4. The photo in the top right of Figure 4 has been taken under a UV lamp with λ = 366 nm (Philips TL8W/08F8T5/BLC), only to show the fluorescence property of compound 3 in solid state It seems the title compound can achieve a good chance among the optoelectronic devices.

Experimental

Elemental analysis for C, H and N was performed using a Thermo Finnigan Flash EA1112 instrument. 1H-NMR and 13C-NMR spectra were determined on a Bruker 250 spectrometer. IR spectra were measured on a Bruker EQUINOX 55 spectrophotometer with the ATR method. Mass spectra were recorded on a Finnigan-MAT 8430 spectrometer. Photophysical data measurements were made by a luminescence PERKIN ELMER LS 50B spectrometer.
3-Cyano-(2-phenethylamino)-4,6-diphenyl pyridine (3). To a magnetically stirred solution of 1,3-diphenylpropane-1,3-dione (0.224 g, 1 mmol) and ZnCl2 (10 mol %) in 10 mL CH2Cl2, malononitrile (0.066 g, 1 mmol), phenethyl amine (0.12 mL, 1 mmol) and N-hydroxy benzamide (50 mol %, 0.68 g) were added in a one-pot manner. The solution was stirred at room temperature for 10 h. The reaction progress was monitored by IR. When one of the CN absorptions (2228 cm−1) in IR spectrum of the reaction mixture had disappeared, the solvent was removed under reduced pressure and the product was purified using column chromatography (silica gel, ethyl acetate/n-hexane: 1/5). The crystals of product were obtained (0.27 g, 72% yield) as yellow crystals. Melting point: 148 °C.

Structural Characterization

IR, νmax: 3353, 2211, 1550 cm−1; δH (250 MHz, CDCl3): 3.08 (2H, t, J = 7. 2 Hz, CH2), 3.96 (2H, q, J = 6.7 Hz, CH2-N), 5.51-5.55 (1H, br s, NH), 7.19 (1H, s, CH of pyridine ring), 7.26–7.42, 7.50–7.59, 7.64–7.68, 8.12–8.15 (15H, 4m, Ph protons) ppm; δC (CDCl3): 35.93 (CH2), 43.25 (CH2-N), 109.61 (CN), 117.41 (CH of pyridine), 126.60, 127.39, 128.76, 128.78, 128.94, 129.73, 130.17, 137.34, 138.34, 139.17, 155.08, 159.06 (aromatic carbons) ppm; MS: m/z = 375 (M+), 298, 272, 255, 221, 195, 120, 91, 77, 75, 43; Anal. Calcd for C26H21N3: C, 83.17; H, 5.64; N, 11.19; Found: C, 83.20; H, 5.69; N, 11.23.

Supplementary materials

Supplementary File 1Supplementary File 2Supplementary File 3Supplementary File 4

Acknowledgments

Support of this study by the Research Council at the University of Tehran is gratefully acknowledged.

Author Contributions

All the authors equally contributed to the research. ZI and HS did the experiments. KA performed the spectroscopic data. SWN performed the X-ray structure. AZ wrote the paper.

Conflicts of Interest

The authors declare no conflict of interest.

References and Notes

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  15. Crystallographic data for the structure of compound 3 reported in this paper have been deposited with the Cambridge Crystallographie Data Center as supplementary publication No. 983903. CCDC 983903 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.com.ac.uk/data_request/cif. (or from the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: +44 1223 336033; E-mail: [email protected]).
Scheme 1. Synthesis of 3-cyano-4,6-diphenyl-2-(phenethylamino)pyridine 3.
Scheme 1. Synthesis of 3-cyano-4,6-diphenyl-2-(phenethylamino)pyridine 3.
Molbank 2014 m831 sch001
Figure 1. X-ray crystal structure of 3.
Figure 1. X-ray crystal structure of 3.
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Figure 2. The fluorescence emission spectrum of compound 3 solutions in CH2Cl2, CH3CN and CH3OH.
Figure 2. The fluorescence emission spectrum of compound 3 solutions in CH2Cl2, CH3CN and CH3OH.
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Figure 3. Photographs of solutions of 3 from left to right in CH2Cl2, CH3OH and CH3CN respectively.
Figure 3. Photographs of solutions of 3 from left to right in CH2Cl2, CH3OH and CH3CN respectively.
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Figure 4. The fluorescence emission spectrum of compound 3 after excitation in 300 nm. The photo in the top right has been taken under a UV lamp with λ = 366 nm (Philips TL8W/08F8T5/BLC).
Figure 4. The fluorescence emission spectrum of compound 3 after excitation in 300 nm. The photo in the top right has been taken under a UV lamp with λ = 366 nm (Philips TL8W/08F8T5/BLC).
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Table 1. Photophysical data: electronic absorption (Abs.) and fluorescence (Flu.) of 3.
Table 1. Photophysical data: electronic absorption (Abs.) and fluorescence (Flu.) of 3.
CH3OHCH3CNCH2Cl2
CompλAbsλFluλAbsλFluλAbsλFlu
3300404300403320401
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