A green approach for an efficient preparation of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles using a TiO2–SiO2 nanocomposite catalyst under solvent-free conditions
-
Ahmad Rabiei
and
Faezeh Shafaei
Abstract
We report on the preparation of a series of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles, a new efficient protocol, via the condensation reaction of aromatic aldehydes, malononitrile, and guanidine nitrate using a TiO2–SiO2 nanocomposite with a molar ratio of 1:1 as a heterogeneous catalyst. The use of a low-cost and reusable catalyst under mild and solvent-free conditions, and simplicity in operation with easier isolation of the products in high to excellent yields are the main advantages of this highly versatile and eco-friendly protocol.
1 Introduction
The utilities of nanoscale metal oxides as heterogeneous catalysts occupy an interesting position in organic reactions owing to their special features such as high surface area and pore sizes as supports [1], [2], [3], [4]. Among transition-metal oxide nanoparticles (NPs), nanosized titanium dioxide (TiO2) NPs have been of considerable interest because of their superior properties such as high catalytic activity, non-toxicity, easily availability, moisture stability, and reusability [5], [6], [7], [8], [9], [10], [11], [12]. During recent years, the use of TiO2 NPs supported on silica shells (TiO2–SiO2 nanocomposite) as catalyst has attracted attention due to the improved structural, chemical, electrical, and optical properties [13].
Pyrimidines and their derivatives are of considerable interest as they possess a wide range of biological properties, such as antibacterial [14], antimicrobial [15], antiviral [16], antihypertensive [17], antimalarial [18], and antitumor [19]. In addition, they can be used as integral backbones of several calcium blockers, antihypertensive agents, α-1a-antagonists, and neuropeptide Y antagonists [20].
There are some examples for the syntheses of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles in the literature via the condensation reaction of aromatic aldehydes, malononitrile, and guanidine hydrochloride or carbonate [21], [22], [23], [24]. Although these procedures have their advantages, research for a simple, efficient, and environmentally friendly procedure that afforded the desired products in higher yields is still strongly desired.
In view of the biological significance of pyrimidinones mentioned above and with the fact that TiO2–SiO2 nanocomposites make the development of a new catalytic procedure possible for organic transformations under milder reaction conditions, we investigate a TiO2–SiO2 nanocomposite as catalyst for the synthesis of a series of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles. It was found that the TiO2–SiO2 nanocomposite is an effective promoter for the synthesis of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles under solvent-free conditions (Scheme 1).
Solvent-free synthesis of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles using a TiO2–SiO2 nanocomposite catalyst.
2 Results and discussion
In continuation of our previous research on the use of nanostructured catalysts for the synthesis of biologically important heterocycles [25], [26], an attempt has been made to synthesize 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles by the reaction of aromatic aldehydes, malononitrile, and guanidine nitrate under solvent-free conditions using a TiO2–SiO2 nanocomposite as catalyst at 80°C (Scheme 1).
In this work, the TiO2–SiO2 nanocomposite was prepared via a simple sol–gel method reported by Nilchi et al. [27]. The XRD pattern of TiO2–SiO2 (Fig. 1) could be indexed as the anatase phase in an amorphous silica matrix. The chemical composition of the as-prepared nanocomposite was also determined by X-ray fluorescence (XRF) spectroscopy, and the results show that the molar ratio was 1:1.
XRD pattern of the synthesized TiO2–SiO2 nanocomposite.
The morphology and grain size of TiO2–SiO2 were investigated by a transmission electron microscopy (TEM) image (Fig. 2). They have a grainy structure with sizes of 5–9 nm.
TEM image of the TiO2–SiO2 nanocomposite.
To optimize the reaction conditions, we first tried to seek the efficiency of the TiO2–SiO2 nanocomposite catalyst, in the model reaction of 4-chlorobenzaldehyde (1d), malononitrile (2), and guanidine nitrate (3). After 2 h with 10, 15, and 20 mol% of the catalyst, yields of 62%, 94%, and 94%, respectively, were obtained. When the reaction was carried out in the absence of the catalyst, it is notable that, after 5 h, no reaction occurred (Table 1, entries 1–4).
Optimization of the reaction conditions using the model reaction of 4-chlorobenzaldehyde (1d), malononitrile (2), and guanidine nitrate (3) under different conditions.
| Entry | Catalyst (mol% with respect to TiO2) | Solvent | Temp. (°C) | Time (h) | Yield (%)a |
|---|---|---|---|---|---|
| 1 | No catalyst | None | 80 | 5 | Trace |
| 2 | Nano TiO2–SiO2 (10%) | None | 80 | 2 | 62 |
| 3 | Nano TiO2–SiO2 (15%) | None | 80 | 2 | 94 |
| 4 | Nano TiO2–SiO2 (20%) | None | 80 | 2 | 94 |
| 5 | Nano TiO2 (20%) | None | 80 | 2.5 | 88 |
| 6 | Nano SiO2 (20%) | None | 80 | 3 | 84 |
| 7 | Nano TiO2–SiO2 (15%) | None | 100 | 2 | 95 |
| 8 | Nano TiO2–SiO2 (15%) | EtOH | Reflux | 3 | 82 |
| 9 | Nano TiO2–SiO2 (15%) | CH2Cl2 | Reflux | 4 | 80 |
| 10 | Nano TiO2–SiO2 (15%) | DMF | Reflux | 2 | 87 |
aIsolated yield.
Thus, the next effort was centralized on the evaluation of the catalytic efficiency of the TiO2–SiO2 nanocomposite compared with two commercial nanopowders, TiO2 NPs (10–30 nm, anatase-TiO2) and SiO2 NPs (20 nm, non-porous). As shown in Table 1, when the reaction was performed using 20 mol% of the TiO2 NPs and the SiO2 NPs alone, the desired product 4d was obtained in 88% and 84% yields, respectively. On the other hand, the study on the catalytic potential of the TiO2–SiO2 nanocomposite showed that the reaction time and the catalyst loading were decreased with higher yield of the product (Table 1, entries 3 and 5, 6).
Increasing the temperature to more than 80°C did not improve the yield (Table 1, entries 3 and 7).
A comparison of the same reaction in various reaction media is also presented in Table 1. Using solvents such as EtOH, CH2Cl2, and DMF was less effective as compared to using solvent-free conditions (Table 1, entries 3 and 8–10).
To establish the reusability, the catalyst was recovered by simple filtration using the centrifugation method and reusing it during four subsequent experiments with a moderate decrease in catalytic activity (Fig. 3).
Reusability of the TiO2–SiO2 nanocatalyst.
Subsequently, the method was extended to substituted aromatic aldehydes, yielding the corresponding products in high to excellent yields (Table 2). The structures of the compounds 4a–4k were confirmed by IR, 1H NMR, and 13C NMR spectroscopic data and also by elemental analyses for new compounds.
Synthesis of a series of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles using a TiO2–SiO2 nanocomposite catalyst.
| Product | Ar | Yield (%)a,b | M.p. (°C) | |
|---|---|---|---|---|
| Obsd. | Lit. | |||
| 4a | C6H5 | 90 | 238–240 | 237–239 [24] |
| 4b | 4-Br-C6H4 | 92 | 259–261 | 260–262 [24] |
| 4c | 3-Cl-C6H4 | 91 | 251–253 | 253–255 [24] |
| 4d | 4-Cl-C6H4 | 94 | 266–267 | 265–266 [24] |
| 4e | 2,4-Cl2-C6H3 | 92 | 233–235 | – |
| 4f | 3-HO-C6H4 | 90 | 268–270 | – |
| 4g | 4-CH3O-C6H4 | 93 | 234–235 | 236–238 [24] |
| 4h | 4-CH3-C6H4 | 91 | 256–258 | 255–257 [24] |
| 4i | 4-NO2-C6H4 | 94 | 244–246 | – |
| 4j | Pridine-4-yl | 95 | 230–232 | – |
| 4k | Thiophen-2-yl | 93 | 222–224 | – |
aYields refer to those of pure isolated products characterized by IR, 1H, and 13C NMR spectral data and by elemental analyses.
bIn all cases, the reaction mixture was stirred for 2 h at 80°C.
In our opinion this protocol has some merits in comparison with several previous methods. To demonstrate the superiority of the present work, we compared the yields, conditions, scope, and generality of this method for the synthesis of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles with the literature procedures (Table 3).
Comparison of the catalytic efficiency of the TiO2–SiO2 nanocomposite with various known catalysts for the preparation of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles.
| Conditions | Ar | Yield (%)a | References |
|---|---|---|---|
| Aromatic aldehydes (1 mmol), malononitrile (1.2 mmol), guanidine hydrochloride (1.2 mmol), potassium carbonate (1.0 g), and a pinch of TBABb in distilled water (30 mL), at reflux, 3–4 h | C6H5, 3-Cl-C6H4, 4-N,N-(CH3)2-C6H4, 2-HO-C6H4, 4-HO-C6H4, 3,4-(CH3O)2-C6H3, 4-CH3O-C6H4 | 63–75 | [21] |
| Aromatic aldehydes (2 mmol), malononitrile (2 mmol), guanidine hydrochloride (2 mmol), and NaOCH3 (2 mmol) in H2O (50 mL) and EtOH (5 mL), at reflux, 3–5 h | C6H5, 4-Br-C6H4, 4-Cl-C6H4, 4-CH3-C6H4 | 64–82 | [22] |
| Aromatic aldehydes (2 mmol), malononitrile (2 mmol), guanidine hydrochloride (2 mmol), and triethylamine (3–4 drops) in toluene (5 mL), under 300 W MWI, 25–45 min | C6H5, 4-Br-C6H4, 4-Cl-C6H4, 4-CH3-C6H4 | 85–96 | [22] |
| Aromatic aldehydes (2 mmol), malononitrile (2 mmol), guanidine hydrochloride (2 mmol), and MgO (0.25 g) in CH3CN (5 mL), at reflux, 8–22 min | C6H5, 4-Br-C6H4, 4-Cl-C6H4, 3-F-C6H4, 4-F-C6H4, 4-CH3-C6H4, 4-CF3-C6H4 | 86–96 | [23] |
| Aromatic aldehydes (2 mmol), malononitrile (3 mmol), guanidine carbonate (1 mmol), and NaOH (1.0 eq) under solvent-free conditions, at 70°C, 4 h | C6H5, 4-Br-C6H4, 3-Cl-C6H4, 4-Cl-C6H4, 3,4-Cl2-C6H3, 4-F-C6H4, 4-CH3O-C6H4, 4-CH3-C6H4, 3,4-(CH3)2-C6H3 | 80–92 | [24] |
| Aromatic aldehydes (1 mmol), malononitrile (1.2 mmol), guanidine nitrate (1.2 mmol), and TiO2–SiO2 nanocomposite (21 mg, 15 mol%) under solvent-free conditions, at 80°C, 2 h | C6H5, 4-Br-C6H4, 3-Cl-C6H4, 4-Cl-C6H4, 2,4-Cl2-C6H3, 3-HO-C6H4, 4-CH3O-C6H4, 4-CH3-C6H4, 4-NO2-C6H4, pridine-4-yl, thiophen-2-yl | 90–95 | This work |
aIsolated yield.
bTBAB, tetrabutylammonium bromide.
A suggested mechanism for the reaction is provided in Scheme 2. This pathway involves the TiO2 NP participation in the formation of alkene 7 which comes from a Knoevenagel condensation between aromatic aldehydes 1 and malononitrile 2, via intermediate 5 and 6. Guanidine nitrate 3 is then added to alkene 7 to generate the Michael adduct 8, which further undergoes intermolecular cyclization and then aromatization to give the product 4.
Proposed mechanism for the synthesis of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles catalyzed by a TiO2–SiO2 nanocomposite.
3 Conclusions
In conclusion, we found a novel solvent-free approach for the synthesis of 2,4-diamino-6-aryl-5-pyrimidinecarbonitrile derivatives. Meanwhile the new method also expands the application of the TiO2–SiO2 nanocomposite in organic synthesis. Compared with previous methods, this method has the advantages of high yields, mild reaction conditions, short reaction time, easy work-up, inexpensive reagents, and environmentally friendly procedure.
4 Experimental section
4.1 Materials and methods
All chemicals used in this work were purchased from Merck and Fluka in high purity (Kimiaexir Chemical Company, Tehran, Iran). Melting points were determined with Electrothermal 9100 apparatus (East Tehran Branch, Islamic Azad University, Tehran, Iran). FT-IR spectra were obtained using a Bruker Equinox 55 Golden Gate Micro-ATR spectrometer (Chemistry and Chemical Engineering Research Center of Iran, Tehran, Iran). 1H NMR and 13C NMR spectra were recorded on a Bruker DRX-500 AVANCE at 500 and 125 MHz, respectively, using tetramethylsilane (TMS) as internal standard and [D6]dimethyl sulfoxide (DMSO) as a solvent (Sharif University of Technology, Tehran, Iran). Elemental analyses were carried out using a Foss-Heraeus CHN-O-Rapid analyzer (Polymer and Petrochemical Institute, Tehran, Iran). The TEM image of the catalyst was obtained on a Philips EM208 transmission electron microscope under acceleration (Nuclear Science and Technology Research Institute AEOI, Tehran, Iran). Powder X-ray diffraction data were determined on a Philips, X’Pert diffractometer using CuKα radiation (λ=1.54 Å) (Nuclear Science and Technology Research Institute AEOI). The composition analysis of the catalyst was carried out by XRF spectroscopy using Oxford ED 2000 equipment (Nuclear Science and Technology Research Institute AEOI).
4.2 General procedure for the preparation of TiO2–SiO2 nanocomposite catalyst
First, titanium tetrachloride (2 mL) was added dropwise into the deionized water (200 mL) in an ice-water bath with strong magnetic stirring. After the hydrolysis was completed, the released HCl was neutralized by adding dilute NH4OH to adjust the pH to 7. The produced solid was filtered and washed with distilled water. The precipitate was dispersed into a 0.3 m HNO3 aqueous solution (200 mL) to remove all the chloride ions. The mixture was then refluxed under strong stirring at 70°C for 16 h, as the titania sol was prepared. Tetraethyl orthosilicate (25 mL) was added dropwise into the above sol and stirred at 70°C for about 0.5 h. Finally, the TiO2–SiO2 nanocomposite powder was filtered and washed with distilled water and then dried in air at ambient temperature [27].
4.3 General procedure for the synthesis of compounds 4a–4k
A mixture of aromatic aldehydes 1 (1 mmol), malononitrile (2, 1.2 mmol), guanidine nitrate (3, 1.2 mmol), and TiO2–SiO2 nanocomposite (21 mg, 15 mol%) was stirred at 80°C for about 2 h. The progress of the reaction was monitored by thin-layer chromatography (acetone–petroleum ether, 1:3). Upon completion of the reaction, hot ethanol (5 mL) was added to the reaction mixture, and the catalyst was filtered and dried in air at ambient temperature for reuse. The organic solution was poured into the ice-cold water (5 mL) and the solid was removed by filtration and then recrystallized from EtOH–H2O to give the pure product in high yield.
4.4 Selected spectroscopic and physical data
4.4.1 2,4-Diamino-6-phenyl-5-pyrimidinecarbonitrile (4a)
Yield: 0.190 g (90%), m.p. 238–240°C (lit: 237–239°C [24]). – IR (KBr, cm−1): νmax 3328, 3196, 3011, 2945, 2388, 2199, 1623, 1587. – 1H NMR: δ=7.12 (s, 2 H, NH2), 7.25 (s, 2 H, NH2), 7.52 (m, 3 H, HAr), 7.73 (m, 2 H, HAr) ppm. – 13C NMR: δ=74.5 (C–CN), 118.9 (CN), 122.5 (2 CH), 127.4 (CH), 130.3 (2 CH), 139.4 (C), 164.6 (C–NH2), 169.1 (C–NH2), 170.9 (C) ppm. – Analysis for C11H9N5 (211.23): calcd. C 62.55, H 4.29, N 33.16; found C 62.44, H 4.21, N 33.29%.
4.4.2 2,4-Diamino-6-(4-bromophenyl)-5-pyrimidinecarbonitrile (4b)
Yield: 0.267 g (92%), m.p. 259–261°C (lit: 260–262°C [24]). – IR (KBr, cm−1): νmax 3501, 3411, 3376, 3143, 2205, 1681, 1616, 1546. – 1H NMR: δ=7.03 (s, 2 H, NH2), 7.16 (s, 2 H, NH2), 7.71 (br s, 4 H, HAr) ppm. – 13C NMR: δ=79.3 (C–CN), 120.1 (CN), 131.1 (2 CH), 134.7 (2 CH), 136.8 (CH), 140.2 (C), 165.4 (C–NH2), 167.0 (C–NH2), 168.9 (C) ppm. – Analysis for C11H8BrN5 (290.12): calcd. C 45.54, H 2.78, N 24.14; found C 45.40, H 2.87, N 24.24%.
4.4.3 2,4-Diamino-6-(3-chlorophenyl)-5-pyrimidinecarbonitrile (4c)
Yield: 0.224 g (91%), m.p. 251–253°C (lit: 253–255°C [24]). – IR (KBr, cm−1): νmax 3489, 3420, 3378, 3126, 2371, 2200, 1623, 1530. – 1H NMR: δ=7.10–7.24 (br s, 4 H, 2 NH2), 7.53 (t, 1 H, J=7.6 Hz, HAr), 7.59 (d, 1 H, J=7.4 Hz, HAr), 7.74 (d, 1 H, J=8.0 Hz, HAr), 7.79 (s, 1 H, HAr) ppm. – 13C NMR: δ=80.4 (C–CN), 120.4 (CN), 128.5 (CH), 130.1 (CH), 132.8 (CCl), 133.7 (CH), 137.1 (CH), 138.6 (C), 163.4 (C–NH2), 166.8 (C–NH2), 170.3 (C) ppm. – Analysis for C11H8ClN5 (245.67): calcd. C 53.78, H 3.28, N 28.51; found C 53.85, H 3.40, N 28.62%.
4.4.4 2,4-Diamino-6-(4-chlorophenyl)-5-pyrimidinecarbonitrile (4d)
Yield: 0.231 g (94%), m.p. 266–267°C (lit: 265–266°C [24]). – IR (KBr, cm−1): νmax 3496, 3431, 3345, 2968, 2450, 2203, 1618, 1525. – 1H NMR: δ=7.04 (s, 2 H, NH2), 7.13 (s, 2 H, NH2), 7.56 (d, 2 H, J=8.6 Hz, HAr), 7.77 (d, 2 H, J=8.6 Hz, HAr) ppm. – 13C NMR: δ=75.5 (C–CN), 118.7 (CN), 129.0 (2 CH), 133.4 (CCl), 136.1 (2 CH), 139.0 (C), 163.2 (C–NH2), 165.9 (C–NH2), 170.4 (C) ppm. – Analysis for C11H8ClN5 (245.67): calcd. C 53.78, H 3.28, N 28.51; found C 53.43, H 3.16, N 28.08%.
4.4.5 2,4-Diamino-6-(2,4-dichlorophenyl)-5-pyrimidinecarbonitrile (4e)
Yield: 0.258 g (92%), m.p. 233–235°C. – IR (KBr, cm−1): νmax 3427, 3376, 3184, 2360, 2194, 1675, 1545. – 1H NMR: δ=7.01 (s, 2 H, NH2), 7.14 (s, 2 H, NH2), 7.46 (m, 2 H, HAr), 7.76 (d, 1 H, J=7.0 Hz, HAr) ppm. – 13C NMR: δ=74.1 (C–CN), 119.2 (CN), 123.0 (CH), 131.3 (CH), 134.3 (CCl), 136.2 (CH), 138.8 (C), 140.7 (CCl), 162.8 (C–NH2), 166.6 (C–NH2), 171.4 (C) ppm. – Analysis for C11H7Cl2N5 (280.12): calcd. C 47.17, H 2.52, N 25.00; found C 47.00, H 2.62, N 24.91%.
4.4.6 2,4-Diamino-6-(3-hydroxyphenyl)-5-pyrimidinecarbonitrile (4f)
Yield: 0.205 g (90%), m.p. 268–270°C. – IR (KBr, cm−1): νmax 3426, 3351, 3268, 3197, 2436, 2361, 2193, 1656, 1526. – 1H NMR: δ=6.92 (br s, 4 H, 2 NH2), 7.78 (m, 1 H, HAr), 7.88 (d, 1 H, J=7.5 Hz, HAr), 8.24 (d, 1 H, J=1.6 Hz, HAr), 8.34 (d, 1 H, J=8.2 Hz, HAr), 9.37 (s, 1 H, OH) ppm. – 13C NMR: δ=76.7 (C–CN), 115.9 (CH), 118.2 (CH), 118.8 (CH), 119.3 (CH), 119.4 (CN), 139.3 (C), 158.4 (COH), 163.8 (C–NH2), 166.0 (C–NH2), 170.4 (C) ppm. – Analysis for C11H9N5O (227.23): calcd. C 58.15, H 3.99, N 30.82; found C 58.02, H 3.87, N 30.74%.
4.4.7 2,4-Diamino-6-(4-methoxyphenyl)-5-pyrimidinecarbonitrile (4g)
Yield: 0.224 g (93%), m.p. 234–235°C (lit: 236–238°C [24]). – IR (KBr, cm−1): νmax 3487, 3416, 3381, 2950, 2206, 1598, 1531. – 1H NMR: δ=3.82 (s, 3 H, OCH3), 7.10–7.21 (br s, 4 H, 2 NH2), 7.05 (d, 2 H, J=8.4 Hz, HAr), 7.76 (d, 2 H, J=8.4 Hz, HAr) ppm. – 13C NMR: δ=55.6 (OCH3), 80.1 (C–CN), 119.5 (CN), 115.7 (2 CH), 136.4 (2 CH), 138.0 (C), 159.6 (COCH3), 162.2 (C–NH2), 167.5 (C–NH2), 171.3 (C) ppm. – Analysis for C12H11N5O (241.25): calcd. C 59.74, H 4.60, N 29.03; found C 59.82, H 4.68, N 29.89%.
4.4.8 2,4-Diamino-6-(4-methylphenyl)-5-pyrimidinecarbonitrile (4h)
Yield: 0.224 g (91%), m.p. 256–258°C (lit: 255–257°C [24]). – IR (KBr, cm−1): νmax 3442, 3417, 3359, 3168, 2207, 1691, 1616, 1535. – 1H NMR: δ=2.35 (s, 3 H, CH3), 7.03–7.10 (br s, 4 H, 2 NH2), 7.29 (d, 2 H, J=7.9 Hz, HAr), 7.67 (d, 2 H, J=7.9 Hz, HAr) ppm. – 13C NMR: δ=20.6 (CH3), 78.2 (C–CN), 120.2 (CN), 125.2 (2 CH), 136.1 (2 CH), 138.5 (CCH3), 139.2 (C), 164.3 (C–NH2), 166.9 (C–NH2), 170.8 (C) ppm. – Analysis for C12H11N5 (225.25): calcd. C 63.99, H 4.92, N 31.09; found C 63.78, H 4.74, N 31.20%.
4.4.9 2,4-Diamino-6-(4-nitrophenyl)-5-pyrimidinecarbonitrile (4i)
Yield: 0.241 g (94%), m.p. 244–246°C. – IR (KBr, cm−1): νmax 3508, 3442, 3292, 3018, 2402, 2226, 1620, 1528, 1505, 1380. – 1H NMR: δ=7.09 (s, 2 H, NH2), 7.20 (s, 2 H, NH2), 7.45 (d, 2 H, J=8.4 Hz, HAr), 8.06 (d, 2 H, J=8.4 Hz, HAr) ppm. – 13C NMR: δ=78.3 (C–CN), 119.6 (CN), 123.4 (2 CH), 134.0 (2 CH), 142.3 (C), 148.7 (CNO2), 165.3 (C–NH2), 168.4 (C–NH2), 171.2 (C) ppm. – Analysis for C11H8N6O2 (256.22): calcd. C 51.57, H 3.15, N 32.80; found C 51.72, H 3.24, N 32.66%.
4.4.10 2,4-Diamino-6-(pyridine-4-yl)-5-pyrimidinecarbonitrile (4j)
Yield: 0.202 g (95%), m.p. 230–231°C. – IR (KBr, cm−1): νmax 3451, 3364, 3275, 3192, 2224, 1661, 1646, 1543. – 1H NMR: δ=6.95–7.07 (br s, 4 H, 2 NH2), 7.48 (d, 2 H, J=7.9 Hz, HAr), 8.26 (d, 2 H, J=7.9 Hz, HAr) ppm. – 13C NMR: δ=80.1 (C–CN), 119.8 (CN), 125.8 (2 CH), 141.3 (C), 146.5 (2 CH), 163.4 (C–NH2), 168.2 (C–NH2), 169.6 (C) ppm. – Analysis for C10H8N6 (212.21): calcd. C 56.60, H 3.80, N 39.60; found C 56.51, H 3.65, N 39.49%.
4.4.11 2,4-Diamino-6-(thiophen-2-yl)-5-pyrimidinecarbonitrile (4k)
Yield: 0.202 g (93%), m.p. 222–224°C. – IR (KBr, cm−1): νmax 3460, 3379, 3172, 3025, 2218, 1654, 1536, 1448, 1412. – 1H NMR: δ=6.79 (m, 2 H, HAr), 7.00–7.08 (br s, 4 H, 2 NH2), 7.18 (m, 1 H, HAr) ppm. – 13C NMR: δ=75.0 (C–CN), 119.4 (CN), 120.5 (CH), 128.6 (CH), 134.9 (CH), 138.7 (C), 167.0 (C–NH2), 168.8 (C–NH2), 169.5 (C) ppm. – Analysis for C9H7N5S (217.25): calcd. C 49.76, H 3.25, N 32.24; found C 49.65, H 3.44, N 32.10%.
Acknowledgment
We thank East Tehran Branch, Islamic Azad University for its financial support.
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Articles in the same Issue
- Frontmatter
- In this Issue
- Lanthanide(III) complexes with μ-SnSe4 and μ-Sn2Se6 linkers: solvothermal syntheses and properties of new Ln(III) selenidostannates decorated with linear polyamine
- A green approach for an efficient preparation of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles using a TiO2–SiO2 nanocomposite catalyst under solvent-free conditions
- New chalcones and thiopyrimidine analogues derived from mefenamic acid: microwave-assisted synthesis, anti-HIV activity and cytotoxicity as antileukemic agents
- Two copper(II) coordination polymers constructed by bis(4-(1H-imidazol-1-yl)phenyl)methanone and dicarboxylate ligands
- Synthesis of functionalised fluorinated pyridine derivatives by site-selective Suzuki-Miyaura cross-coupling reactions of halogenated pyridines
- Synthesis, crystal structure and biological activities of a Ag(I) complex based on the V-shaped ligand 1,3-bis(1-benzylbenzimidazol-2-yl)-2-thiapropane
- Ternary rhombohedral Laves phases RE2Rh3Ga (RE = Y, La–Nd, Sm, Gd–Er)
- Bixbyite-type phases in the system Ta-Zr-O-N
- Note
- Oxide meets silicide – synthesis and single-crystal structure of Ca21SrSi24O2
Articles in the same Issue
- Frontmatter
- In this Issue
- Lanthanide(III) complexes with μ-SnSe4 and μ-Sn2Se6 linkers: solvothermal syntheses and properties of new Ln(III) selenidostannates decorated with linear polyamine
- A green approach for an efficient preparation of 2,4-diamino-6-aryl-5-pyrimidinecarbonitriles using a TiO2–SiO2 nanocomposite catalyst under solvent-free conditions
- New chalcones and thiopyrimidine analogues derived from mefenamic acid: microwave-assisted synthesis, anti-HIV activity and cytotoxicity as antileukemic agents
- Two copper(II) coordination polymers constructed by bis(4-(1H-imidazol-1-yl)phenyl)methanone and dicarboxylate ligands
- Synthesis of functionalised fluorinated pyridine derivatives by site-selective Suzuki-Miyaura cross-coupling reactions of halogenated pyridines
- Synthesis, crystal structure and biological activities of a Ag(I) complex based on the V-shaped ligand 1,3-bis(1-benzylbenzimidazol-2-yl)-2-thiapropane
- Ternary rhombohedral Laves phases RE2Rh3Ga (RE = Y, La–Nd, Sm, Gd–Er)
- Bixbyite-type phases in the system Ta-Zr-O-N
- Note
- Oxide meets silicide – synthesis and single-crystal structure of Ca21SrSi24O2
