Co3O4/NiO?GQD?SO3H nanocomposite as a superior catalyst for the synthesis of chromenpyrimidines

Article abstract of DOI:10.1039/c9ra05896f

A three-component reaction involving aromatic aldehydes, 6-amino-1,3-dimethyluracil and 4-hydroxycoumarin was achieved in the presence of the Co₃O₄/NiO?GQD?SO₃H nanocomposite as a highly effective heterogeneous catalyst to

Full text of DOI:10.1039/c9ra05896f

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Co3O4/NiO@GQD@SO3H nanocomposite as
a superior catalyst for the synthesis of
Cite this: RSC Adv., 2019, 9, 37344
chromenpyrimidines†
*
Javad Safaei-Ghomi
and Zahra Omidshafiei
A
three-component reaction involving aromatic aldehydes, 6-amino-1,3-dimethyluracil and 4-
hydroxycoumarin was achieved in the presence of the Co3O4/NiO@GQD@SO3H nanocomposite as
highly effective heterogeneous catalyst to produce chromenpyrimidines. The catalyst was
a
Received 30th July 2019
Accepted 28th October 2019
characterized via FT-IR, SEM, XRD, EDS, TGA, BET and VSM. This new catalyst was demonstrated to be
highly effective in the preparation of chromenpyrimidines. Atom economy, low catalyst loading, reusable
catalyst, applicability to a wide range of substrates and high product yields are some of the important
features of this protocol.
DOI: 10.1039/c9ra05896f
rsc.li/rsc-advances
dots (GQDs) are a new member of the carbon nanostructure
family, which have quasi-spherical structures. GQDs have
1. Introduction
gained intensive attention due to their signicant features,
biological,15 biomedical,16 and therapeutic applications,17 as
a new class of photocatalysts18 and surfactants,19 and electro-
chemical biosensing,20 electrocatalytic,21 lithium battery,22
optical and photovoltaic,23 photoluminescence,24,25 bioimag-
ing,26 and catalytic applications.27 The potential applications of
N-graphene quantum dots were recently reviewed based on
experimental and theoretical studies.28–31 The synthesis of
highly efficient nanocomposite catalysts for the synthesis of
organic compounds is still a big challenge. To obtain a larger
surface area and more active sites, nanocatalysts are function-
alized with active groups.32–34 It has been demonstrated that the
decoration of nanocatalysts with GQDs prevents the aggrega-
tion of ne particles, and thus increases the effective surface
area and number of reactive sites for efficient catalytic reac-
tions. The chemical groups on GQD can catalyze chemical
reactions, and their –COOH and –SO3H groups can serve as acid
catalysts for many reactions.27–36 Herein, we report the use of
a Co3O4/NiO@GQD@SO3H nanocomposite as a new efficient
catalyst for the preparation of chromenpyrimidines through
a three-component reaction involving aromatic aldehydes, 6-
amino-1,3-dimethyluracil and 4-hydroxycoumarin (Scheme 1).
Chromenpyrimidines are a common scaffold in multiple
bioactive compounds and possess several pharmacological
properties.1 These compounds are used as analgesic, anti-
pyretic,2 anti-microbial,3,4 anti-biolm,5 anti-inammatory,6
anticancer,7 antitubercular agents.8 Some other examples of
pyrimidines as prominent drug molecules include uramustine,
piritrexim isetionate, tegafur, oxuridine, methotrexate,
trimethoprim, piromidic acid, tetroxoprim and dipyridamole,
which have high bioavailability, slow onset and prolonged
effect.9 Chromenpyrimidines have been regarded as signicant
targets of organic synthesis. Therefore, the development of
effective methods for the preparation of chromenpyrimidines is
an attractive challenge. Several methods have been reported for
the preparation of chromenpyrimidines in the presence of
diverse catalysts including L-proline-derived secondary amino-
thiourea,10 sulfamic acid,11 Zr(HSO4)4,12 L-proline,13 and
bifunctional thiourea-based organocatalyst.14 However, some of
the reported procedures have disadvantages including long
reaction times, use of toxic and non-reusable catalysts and
undesirable reaction conditions. Therefore, to avoid these
drawbacks, the search for effective methods for the preparation
of chromenpyrimidines is still desirable. Nanoparticles exhibit
good catalytic activity owing to their large surface area and
active sites. Metal oxides are a broad class of materials that have
been researched extensively due to their unique attributes and
potential applications in various elds. Graphene quantum
2. Results and discussion
Initially, we prepared Co3O4/NiO nanoparticles via simple
techniques. A facile hydrothermal method was used for the
preparation of N-GQDs.37 Sulfonated graphene quantum dots
were prepared using chlorosulfonic acid.38 The XRD patterns of
Co3O4/NiO, Co3O4/NiO@N-GQDs and Co3O4/NiO@GQD@SO3H
nanocomposite are shown in Fig. 1, which conrm the presence
of both NiO (JCPDS No.22-1189) and Co3O4 (JCPDS no 65-3103).
Department of Organic Chemistry, Faculty of Chemistry, University of Kashan, Kashan,
P. O. Box 87317-51167, I. R. Iran. E-mail: safaei@kashanu.ac.ir; Fax: +98-31-
55912397; Tel: +98-31-55912385
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c9ra05896f
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Scheme 1 Synthesis of chromenpyrimidines using the Co3O4/NiO@GQD@SO3H nanocomposite.
To investigate the morphology and particle size of the
nanoparticles, SEM images of Co3O4/NiO and Co3O4/NiO@
GQD@SO3H nanocomposite were measured, as shown in Fig. 2.
The SEM images of the Co3O4/NiO@GQD@SO3H nano-
composite show the formation of uniform particles, and the
energy-dispersive X-ray spectrum (EDS) conrms the presence
of Co, Ni, O, S and C species in the structure of the nano-
composite (Fig. 3).
The magnetic properties of the nanocomposites before and
aer their decoration with GQDs were tested using a vibrating-
sample magnetometer (VSM) (Fig. 4). The lower magnetism of
the as-synthesized Co3O4/NiO@GQD@SO3H compared with
that of Co3O4/NiO is ascribed to the antiferromagnetic behavior
of the GQDs as a dopant. These results demonstrate that the
magnetization property decreased by coating and
functionalization.39,40
The FT-IR spectra of Co3O4/NiO, Co3O4/NiO@N-GQD and
Co3O4/NiO@GQD@SO3H nanocomposite are shown in Fig. 5.
The absorption peak at 3335 cmꢀ1 is related to the stretching
vibrational absorptions of OH. The peaks at 461.4, 568.4, and
657.1 cmꢀ1 correspond to Ni–O, Co2+–O and Co3+–O respec-
tively. The characteristic peaks at 3440 cmꢀ1 (O–H stretching
Fig. 1 XRD patterns of (a) Co3O4/NiO, (b) Co3O4/NiO@GQDs and (c)
Co3O4/NiO@GQD@SO3H.
Fig. 2 SEM images of (a) Co3O4/NiO and (b) Co3O4/NiO@GQD@SO3H.
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Fig. 3 EDS spectra of (a) Co3O4/NiO and (b) Co3O4/NiO@GQD@SO3H.
vibration), 1705 cmꢀ1 (C]O stretching vibration), and indicate that the BET specic surface area of Co3O4/NiO
1125 cmꢀ1 (C–O–C stretching vibration) appear in the spectrum improved from 12.25 to 32.43 m2 gꢀ1 aer modication with the
in Fig. 5b. The peak at approximately 1475–1580 cmꢀ1 is GQDs; therefore, more active sites were introduced on the
attributed to the C]C bonds. The presence of the sulfonyl surface of Co3O4/NiO@GQD@SO3H.
group is also veried by the peaks at 1215 and 1120 cmꢀ1. The
broad peak at 3350 cmꢀ1 is related to the stretching vibrational thermal stability of the Co3O4/NiO@GQD@SO3H nano-
absorptions of OH (SO3H) (Fig. 5c). composite. The nanocomposite displayed suitable thermal
TGA (thermogravimetric analysis) was used to evaluate the
The BET specic surface area of the Co3O4/NiO and Co3O4/ stability without a signicant decrease in weight (Fig. 7). The
NiO@GQD@SO3H nanocomposites was measured by nitrogen weight loss at temperatures below 210 ꢁC is owing to the
gas adsorption–desorption isotherms (Fig. 6). The results removal of physically adsorbed solvent and surface hydroxyl
Fig. 4 VSM curves of (a) Co3O4/NiO, (b) Co3O4/NiO@GQDs and (c) Co3O4/NiO@GQD@SO3H.
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aromatic aldehydes either bearing electron-withdrawing
substituents or electron-donating substituents.
We also investigated the recyclability of the Co3O4/
NiO@GQD@SO3H nanocomposite as a catalyst for the model
reaction under reux conditions in ethanol. The results showed
that nanocomposite can be reused several times without
noticeable loss in its catalytic activity (yield in the range of 93%
to 91%) (Fig. 9).
The plausible mechanism for the preparation of chro-
menpyrimidines using the Co3O4/NiO@GQD@SO3H nano-
composite is shown in Scheme 2. Firstly, we assumed that the
reaction occurs via condensation between 6-amino-1,3-
dimethyluracil and aldehyde to form intermediate I on the
active sites of the Co3O4/NiO@GQD@SO3H nanocatalyst. Then,
4-hydroxycoumarin is added to intermediate I to give interme-
diate II. Then, migration of the hydrogen atom provides the
nal product (Scheme 2).
Fig. 5 FT-IR spectra of (a) Co3O4/NiO, (b) Co3O4/NiO@GQDs and (c)
Co3O4/NiO@GQD@SO3H.
To study the applicability of this method for large-scale
synthesis, we performed selected reactions at the 10 mmol
scale. As can be seen, the reactions on a large scale gave the
product with a gradual decrease in reaction yield (Table 3).
To compare the efficiency of the Co3O4/NiO@GQD@SO3H
nanocomposite with the reported catalysts for the synthesis of
chromenpyrimidines, we tabulated the results in Table 4. As
indicated in Table 4, the Co3O4/NiO@GQD@SO3H nano-
composite is superior to the reported catalysts. As expected, the
increased surface area due to the small particle size increased
the reactivity of the catalyst, which is responsible for the
accessibility of the substrate molecules on the catalyst surface.
The activity of catalysts is inuenced by their acid–base
properties and many other factors such as surface area,
geometric structure (particularly pore structure), distribution of
sites and polarity of the surface sites.41,42 The SO3H groups
distributed on the surface of Co3O4/NiO@GQDs activate the
groups of the substrates. In this mechanism, the surface atoms
of Co3O4/NiO@GQD@SO3H activate the C]O and C]N groups
for better reaction with nucleophiles. The Co3O4/
NiO@GQD@SO3H nanocomposite has Lewis and Brønsted acid
properties, which increase the activity of the catalyst.
groups. The curve indicates a weight loss of about 14.06% from
150 ꢁC to 500 ꢁC, which is attributed to the oxidation and
degradation of the GQD.
The X-ray photoelectron spectroscopy (XPS) analysis of the
Co3O4/NiO@GQD@SO3H nanocomposite is shown in Fig. 8. In
the wide-scan spectrum of the nanocatalyst, the predominant
components are Ni 2p1/2 (873.4 eV), Ni 2p3/2 (854.4 eV), Co 2p1/2
(792.6 eV), Co 2p3/2 (780.4 eV), O 1s (529.8 eV), N 1s (400 eV), C 1s
(284.5 eV) and S 2p (164.3 eV).
Initially, we carried out a three-component reaction with 4-
nitrobenzaldehyde, 6-amino-1,3-dimethyluracil and 4-hydrox-
ycoumarin as a model reaction. The model reactions were per-
formed in the presence of NaHSO4, ZrO2, p-TSA, Co3O4, NiO,
Co3O4/NiO, Co3O4/NiO@GQDs and Co3O4/NiO@GQD@SO3H
nanocomposite as catalysts. The reactions were tested using
diverse solvents including ethanol, acetonitrile, water and
dimethylformamide. The best results were obtained in EtOH
and we found that the reaction gave convincing results in the
presence of the Co3O4/NiO@GQD@SO3H nanocomposite (5
mg) under reux conditions (Table 1).
A series of aromatic aldehydes were studied under the
optimum conditions (Table 2). Good yields were obtained using
Fig. 6 BET specific surface area of (a) Co3O4/NiO and (b) Co3O4/NiO@GQD@SO3H.
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Fig. 7 TGA of Co3O4/NiO@GQD@SO3H nanocomposite.
3.2. Preparation of Co3O4/NiO nanoparticles
Co(NO3)3 and NiCl2 with a 3 : 1 molar ratio were dissolved in
ethylene glycol. Aerward, the appropriate amount of aqueous
ammonia solution (28 wt%) was added to the above solution
until the pH reached 10. Then, the transparent solution was
ꢁ
placed in an autoclave at 150 C for 4 h. The obtained precipi-
tate was washed twice with methanol and dried at 60 ꢁC for 8 h.
ꢁ
Finally, the product was calcined at 500 C for 2 h.
3.3. Preparation of Co3O4/NiO@N-GQD nanocomposite
1 g citric acid and was dissolved in 20 mL deionized water, and
stirred to form a clear solution. Subsequently, 0.3 mL ethyl-
enediamine was added to the above solution and mixed to
obtain a clear solution. Then, 0.1 g Co3O4/NiO nanoparticles
was added to the mixture. The mixture was stirred at room
temperature for 5 min. Then the solution was transferred to
a 50 mL Teon-lined stainless autoclave, which was sealed and
heated to 180 ꢁC for 12 h in an electric oven. Finally, the as-
prepared nanostructured Co3O4/NiO@GQDs was obtained,
which was washed several times with deionized water and
ethanol, and then dried in an oven until a constant weight was
achieved.
Fig. 8 X-ray photoelectron spectroscopy (XPS) analysis of the Co3O4/
NiO@GQD@SO3H nanocomposite.
3. Experimental
3.1. Chemicals and apparatus
NMR spectra were recorded on a Bruker Avance-400 MHz
spectrometer in the presence of tetramethylsilane as an
internal standard. IR spectra were recorded on an FT-IR
Magna 550 spectrometer using KBr plates. Melting points
were determined on an Electrothermal 9200, and are not
corrected. Elemental analyses (C, H, and N) were performed
on a Carlo ERBA Model EA 1108 analyzer. Powder X-ray
diffraction (XRD) was performed on a Philips X'pert diffrac-
tometer with monochromatized Cu Ka radiation (l ¼ 1.5406
3.4. Preparation of Co3O4/NiO@GQD@SO3H
nanocomposite
1 g of Co3O4/NiO@N-GQD nanocomposite was dispersed in dry
CH2Cl2 (10 mL) and sonicated for 5 min. Then, chlorosulfonic
acid (0.8 mL in dry CH2Cl2) was added dropwise to a cooled (ice-
bath) mixture of Co3O4/NiO@N-GQDs for 30 min under N2 with
vigorous stirring. The mixture was stirred for 120 min, while the
residual HCl was removed by suction. The resulted Co3O4/
NiO@GQD@SO3H nanocomposite was separated, washed several
times with dried CH2Cl2 before drying under vacuum at 60 ꢁC.
˚
A). The microscopic morphology of the nanocatalyst was
visualized by SEM (MIRA3). Thermogravimetric analysis (TGA)
curves were measured on a V5.1A DUPONT 2000. The
magnetic measurement of the samples was performed in
a vibrating sample magnetometer (VSM) (Meghnatis Daghigh
Kavir Co.; Kashan Kavir; Iran).
3.5. General procedure for the preparation of
chromenpyrimidines
A mixture of aldehyde (1 mmol), 6-amino-1,3-dimethyluracil (1
mmol), 4-hydroxycoumarin (1 mmol) and
5 mg Co3O4/
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Table 1 Optimization of the reaction conditions using different catalystsa
Entry
Catalyst (amount)
Solvent (reux)
Time (min)
Conversion efficiency
Yieldb (%)
1
2
3
4
5
6
7
8
None
Et3N (5 mol%)
NaHSO4 (4 mol%)
ZrO2 (4 mol%)
pTSA NPs (5 mol%)
Nano-Co3O4
Nano-NiO
Co3O4/NiO nanocomposite
Co3O4/NiO@GQD nanocomposite
Co3O4/NiO@GQD@SO3H nanocomposite (3 mg)
Co3O4/NiO@GQD@SO3H nanocomposite (5 mg)
Co3O4/NiO@GQD@SO3H nanocomposite (7 mg)
Co3O4/NiO@GQD@SO3H nanocomposite (5 mg)
Co3O4/NiO@GQD@SO3H nanocomposite (5 mg)
Co3O4/NiO@GQD@SO3H nanocomposite (5 mg)
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
H2O
300
300
250
250
250
250
250
250
150
80
80
80
100
90
80
NR
28
37
43
49
40
45
55
68
81
87
87
69
71
77
NR
35
42
48
54
45
52
60
72
85
93
93
72
76
82
9
10
11
12
13
14
15
DMF
CH3CN
a
4-Nitrobenzaldehyde (1 mmol), 6-amino-1,3-dimethyluracil (1 mmol) and 4-hydroxycoumarin (1 mmol). b Isolated yield.
NiO@GQD@SO3H nanocomposite was stirred in 5 mL ethanol 117.35, 124.20, 124.82, 128.43, 128.96, 130.78, 132.96, 138.02,
under reux. The reaction was monitored by TLC. Aer 150.52, 152.40, 155.62, 164.25, 164.52, 166.14; anal. calcd for
completion of the reaction, the solution was ltered, and the C22H18ClN3O5: C, 60.07%; H, 4.12%; N, 9.55%. Found: C,
heterogeneous catalyst was recovered. Water was added, and 60.15%; H, 4.18%; N, 9.42%.
the precipitate was collected by ltration and washed with
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)(4-methoxy
water. The crude product was recrystallized or washed with phenyl) methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-dione (4c).
ethanol to give the pure product.
Light yellow solid, m.p.: 178–180 ꢁC; IR (KBr): 3413, 3238, 2952,
1695, 1613, 1568, 1508, 1450, 1253, 767 cmꢀ1 1H NMR (400
,
MHz, DMSO-d6) d: 3.14 (s, 3H), 3.37 (s, 3H), 3.69 (s, 3H), 5.61 (s,
1H), 6.78–6.80 (d, J ¼ 8.0 Hz, 2H), 7.03–7.05 (d, J ¼ 8.0 Hz, 2H),
7.32–7.84 (m, 6H), 13.98 (s, 1H, OH); 13C NMR (100 MHz,
DMSO-d6) d: 28.66, 31.02, 35.83, 55.43, 87.45, 105.43, 113.95,
116.62, 117.42, 124.15, 124.75, 127.90, 130.32, 132.82, 150.56,
152.42, 155.57, 157.88, 164.20, 164.54, 166.29; anal. calcd for
3.6. Spectral data
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)(phenyl)
methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-dione (4a). White
solid; m.p. 220–222 C; IR (KBr): 3432, 3234, 2964, 1695, 1664,
ꢁ
1616, 1569, 1444, 1356, 754 cmꢀ1; 1H NMR (400 MHz, DMSO-d6)
d: 3.14 (s, 3H, –CH3), 3.40 (s, 3H, –CH3), 5.62 (s, 1H, –CH), 7.16–
7.85 (m, 11H, ArH, –NH2), 13.99 (s, 1H, –OH); 13C NMR (100
MHz, DMSO-d6) d: 28.68, 31.02, 36.53, 87.26, 105.11, 116.62,
117.41, 124.17, 124.76, 126.14, 126.80, 128.55, 132.87, 138.74,
150.50, 152.44, 155.63, 164.27, 164.55, 166.27; anal. calcd for
C
23H21N3O6: C, 63.44%; H, 4.86%; N, 9.65%. Found: C, 63.49%;
H, 4.74%; N, 9.59%.
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
(4-nitrophenyl)
methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-
dione (4d). Light yellow solid; m.p.: 240–242 ꢁC; IR (KBr): 3396,
C
22H19N3O5: C, 65.18%; H, 4.72%; N, 10.37%. Found: C,
3210, 2903, 1685, 1619, 1571, 1514, 1346, 769 cmꢀ1; H NMR
1
65.20%; H, 4.59%; N, 10.25%.
(400 MHz, DMSO-d6) d: 3.14 (s, 3H), 3.49 (s, 3H), 5.75 (s, 1H),
7.35–8.10 (m, 10H), 13.96 (s, 1H, OH); 13C NMR (100 MHz,
DMSO-d6) d: 28.69, 31.05, 36.52, 86.48, 104.72, 117.30, 121.45,
121.63, 124.22, 130.00, 133.04, 134.12, 141.74, 148.41, 150.46,
152.47, 155.80, 164.34, 164.55, 165.98; anal. calcd for
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)(4-
chlorophenyl)
dione (4b). White solid; m.p. 218–220 C; IR (KBr): 3405, 3211,
2921, 1695, 1663, 1617, 1493, 1448, 763 cmꢀ1 1H NMR (400
MHz, DMSO-d6) d: 3.14 (s, 3H), 3.37 (s, 3H), 5.61 (s, 1H), 7.17–
7.85 (m, 10H, ArH and NH2), 13.98 (s, 1H, OH); 13C NMR (100
MHz, DMSO-d6) d: 28.72, 31.14, 36.17, 86.98, 104.96, 116.60,
methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-
ꢁ
;
C
22H18N4O7: C, 58.67%; H, 4.03%; N, 12.44%; found C, 58.72%;
H, 4.09%; N, 12.52%.
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Table 2 Synthesis of chromenpyrimidines using the Co3O4/NiO@GQD@SO3H nanocomposite (5 mg) under reflux conditionsa
mp (ꢁC)
(reported)
Entry
Aldehyde (1a–1l)
Product
Time (min)
Conversion efficiency
Yieldb (%)
mp (ꢁC) (ref.)
1
80
80
88
218–220 (10)
220–222
2
80
82
90
219–220 (10)
218–220
3
90
72
85
180–181 (10)
178–180
4
80
87
93
240–242 (13)
240–242
5
80
80
88
230–232 (10)
230–232
6
7
110
100
75
77
83
87
—
230–232
232–234
—
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Table 2 (Contd.)
mp (ꢁC)
(reported)
Entry
Aldehyde (1a–1l)
Product
Time (min)
Conversion efficiency
Yieldb (%)
mp (ꢁC) (ref.)
8
110
74
81
—
240–242
9
90
76
85
202–204 (10)
202–204
10
85
80
87
—
200–202
11
80
81
89
236–238 (10)
236–238
12
100
74
84
257–259 (13)
257–259
13
80
79
89
210–212 (10)
210–212
14
80
81
88
245–247 (13)
245–247
a
Aromatic aldehydes (1 mmol), 6-amino-1,3-dimethyluracil (1 mmol) and 4-hydroxycoumarin (1 mmol). b Isolated yield.
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Table 3 The large-scale synthesis of some chromenpyrimidines using
the Co3O4/NiO@GQD@SO3H nanocomposite (5 mg)
Entry
Product
Time (min)
Yielda (%)
1
2
3
4
5
4a
4c
4d
4i
90
95
80
95
80
86
83
90
82
87
4k
a
Isolated yield.
(m, 6H), 9.14 (s, 1H, OH), 13.97 (s, 1H, OH); 13C NMR (100 MHz,
DMSO-d6) d: 28.64, 30.96, 35.74, 87.54, 105.45, 115.35, 116.55,
117.40, 124.12, 124.73, 127.77, 128.41, 132.79, 150.50, 152.35,
155.43, 155.76, 164.17, 164.49, 166.27. Anal. calcd for
Fig. 9 Recycling of the Co3O4/NiO@GQD@SO3H nanocomposite as
a catalyst for the model reaction.
C
22H19N3O6: C, 62.70%; H, 4.54%; N, 9.97%; found C, 62.78%;
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
H, 4.59%; N, 10.05%.
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
(3-hydroxyphenyl) methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-
(3-nitrophenyl)
methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-
dione (4e). Light yellow solid; m.p.: 230–232 ꢁC; IR (KBr): 3460,
3209, 2923, 1699, 1673, 1523, 1437, 1343, 772 cmꢀ1; H NMR
1
ꢁ
dione (4g). White solid; m.p. 232–234 C; IR (KBr): 3429, 3306,
2957, 1695, 1670, 1617, 1569, 1447, 1354, 760 cmꢀ1; H NMR
1
(400 MHz, DMSO-d6) d: 3.14 (s, 3H), 3.38 (s, 3H), 5.76 (s, 1H),
7.36–8.06 (m, 10H), 13.97 (s, 1H, OH); 13C NMR (100 MHz,
DMSO-d6) d: 28.69, 31.05, 36.52, 86.48, 104.70, 116.54, 117.35,
121.42, 121.62, 124.80, 124.24, 130.14, 133.24, 134.22, 141.75,
148.45, 150.49, 152.42, 155.92, 164.42, 164.45, 165.85; anal.
calcd for C22H18N4O7: C, 58.67%; H, 4.03%; N, 12.44%; found C,
58.75%; H, 4.12%; N, 12.54%.
(400 MHz, DMSO-d6) d: 3.15 (s, 3H), 3.38 (s, 3H), 5.55 (s, 1H),
6.53–7.67 (m, 10H), 9.12 (s, 1H, OH), 14.03 (s, 1H, OH); 13C NMR
(100 MHz, DMSO-d6) d: 28.72, 30.94, 35.72, 87.55, 104.55,
115.34, 116.52, 116.58, 117.42, 124.14, 124.25, 124.78, 127.75,
128.43, 132.79, 151.22, 152.34, 155.42, 155.78, 164.15, 164.45,
166.28. Anal. calcd for C22H19N3O6: C, 62.70%; H, 4.54%; N,
9.97%; found C, 62.72%; H, 4.55%; N, 10.09%.
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
(4-hydroxyphenyl) methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
ꢁ
dione (4f). White solid; m.p. 230–232 C; IR (KBr): 3364, 3219,
(2-hydroxyphenyl) methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-
dione (4h). White solid; m.p. 240–242 ꢁC; IR (KBr): 3432, 3306,
1695, 1671, 1569, 1509, 1444, 1358, 769 cmꢀ1 1H NMR (400
;
2958, 1695, 1607, 1617, 1447, 760 cmꢀ1 1H NMR (400 MHz,
;
MHz, DMSO-d6) d: 3.14 (s, 3H), 3.49 (s, 3H), 5.51 (s, 1H), 6.60–
6.62 (d, J ¼ 8.0 Hz, 2H), 6.90–6.92 (d, J ¼ 8.0 Hz, 2H), 7.29–7.84
DMSO-d6) d: 3.15 (s, 3H), 3.38 (s, 3H), 5.55 (s, 1H), 6.63–7.87 (m,
Scheme 2 Proposed mechanism for the three-component reaction.
37352 | RSC Adv., 2019, 9, 37344–37354
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Table 4 Comparison of the catalytic activity of the Co3O4/NiO@GQD@SO3H nanocomposite (5 mg) with that of other reported catalysts for the
synthesis chromenpyrimidines (4b)
Entry
Catalyst (conditions)
Time (min)
Conversion efficiency
Yielda (%)
Ref.
1
2
L-proline, 20 mol%, EtOH, reux
Bifunctional thiourea-based
360
240
75
79
83
86
13
14
organocatalyst, 20 mol%, H2O, reux
Sulfamic acid, 30 mol%, (EtOH : H2O:
1 : 1), ultrasound irradiation
3
4
30
80
77
82
85
90
11
Co3O4/NiO@GQD@SO3H
This work
nanocomposite (5 mg, EtOH, reux)
a
Isolated yield.
10H), 9.11 (s, 1H, OH), 14.03 (s, 1H, OH); 13C NMR (100 MHz, (s, 3H), 3.38 (s, 3H), 5.57 (s, 1H), 7.02–7.85 (m, 10H), 13.99 (s,
DMSO-d6) d: 28.67, 31.02, 36.40, 87.35, 104.98, 113.16, 113.69, 1H, OH); 13C NMR (100 MHz, DMSO-d6) d: 23.8, 28.1, 30.3, 32.9,
116.58, 116.59, 117.48, 124.23, 124.81, 124.83, 129.47, 132.93, 35.6, 87.1, 104.4, 115.8, 116.9, 123.7, 123.9, 125.8, 126.1, 131.9,
140.27, 150.51, 152.36, 155.52, 157.72, 164.48, 166.23. Anal. 135.2, 145.5, 149.9, 151.9, 155.0, 163.8, 164.1, 168.3; anal. calcd
calcd for C22H19N3O6: C, 62.70%; H, 4.54%; N, 9.97%; found C, for C25H25N3O5: C, 67.10%; H, 5.63%; N, 9.39%; found C,
62.82%; H, 4.62%; N, 9.98%.
67.19%; H, 5.75%; N, 9.45%.
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
(4-methylphenyl) methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)- (2-bromophenyl) methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-
ꢁ
dione (4i). White solid; m.p. 202–204 C; IR (KBr): 3411, 3212, dione (4m). White solid; m.p. 210–212 ꢁC; IR (KBr): 3402, 3210,
2922, 1697, 1665, 1618, 1569, 1353, 764 cmꢀ1 1H NMR (400 2925, 1676, 1665, 1618, 1489, 1447, 765 cmꢀ1 1H NMR (400
;
;
MHz, DMSO-d6) d: 2.24 (s, 3H), 3.14 (s, 3H), 3.37 (s, 3H), 5.57 (s, MHz, DMSO-d6) d: 3.12 (s, 3H), 3.35 (s, 3H), 5.57 (s, 1H), 7.12–
1H), 6.96–7.85 (m, 10H), 13.98 (s, 1H, OH); 13C NMR (100 MHz, 7.86 (m, 10H), 13.96 (s, 1H, OH); 13C NMR (100 MHz, DMSO-d6)
DMSO-d6) d: 20.60, 28.32, 30.64, 35.74, 87.30, 104.72, 116.25, d: 28.74, 31.16, 36.10, 86.94, 104.92, 116.63, 117.29, 124.25,
123.72, 124.17, 124.42, 126.37, 128.82, 132.58, 134.74, 135.13, 124.82, 126.35, 127.52, 128.40, 128.92, 130.75, 132.96, 138.05,
150.18, 152.02, 155.12, 164.15, 165.93, 167.75; anal. calcd for 150.56, 152.47, 155.65, 164.22, 164.55, 166.14; anal. calcd for
C
23H21N3O5: C, 65.86%; H, 5.05%; N, 10.02%; found C, 65.92%;
C22H18BrN3O5: C, 54.56%; H, 3.75%; N, 8.68%. Found: C,
H, 5.15%; N, 10.08%.
54.65%; H, 3.86%; N, 8.77%.
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
(3-methylphenyl) methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)- (3-bromophenyl) methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-
ꢁ
dione (4j). White solid; m.p. 200–202 C; IR (KBr): 3403, 3229, dione (4n). White solid; m.p. 245–247 ꢁC; IR (KBr): 3405, 3210,
2923, 1699, 1695, 1445, 758 cmꢀ1; 1H NMR (400 MHz, DMSO-d6) 2924, 1673, 1665, 1617, 1489, 1445, 764 cmꢀ1 1H NMR (400
;
d: 2.21 (s, 3H), 3.15 (s, 3H), 3.38 (s, 3H), 5.59 (s, 1H), 6.92–7.86 MHz, DMSO-d6) d: 3.13 (s, 3H), 3.35 (s, 3H), 5.59 (s, 1H), 7.10–
(m, 10H), 13.97 (s, 1H, OH); 13C NMR (100 MHz, DMSO-d6) d: 7.89 (m, 10H), 13.98 (s, 1H, OH); 13C NMR (100 MHz, DMSO-d6)
21.63, 28.66, 30.98, 36.37, 87.34, 105.11, 116.58, 117.37, 123.91, d: 28.74, 31.18, 36.17, 86.95, 104.94, 116.62, 117.31, 124.26,
124.18, 124.77, 126.87, 127.29, 128.42, 132.85, 137.50, 138.66, 124.85, 125.33, 126.54, 128.42, 128.94, 130.72, 132.90, 138.07,
150.50, 152.37, 155.52, 164.26, 164.54, 166.25; anal. calcd for 150.52, 152.43, 155.64, 164.22, 164.50, 166.12; anal. calcd for
C
23H21N3O5: C, 65.86%; H, 5.05%; N, 10.02%; found C, 65.96%;
C22H18BrN3O5: C, 54.56%; H, 3.75%; N, 8.68%. Found: C,
H, 5.18%; N, 10.12%.
54.65%; H, 3.87%; N, 8.79%.
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
(4-bromophenyl) methyl)-1,3-dimethylpyrimidine-2,4(1H,3H)-
ꢁ
4. Conclusions
dione (4k). White solid; m.p. 236–238 C; IR (KBr): 3404, 3212,
2921, 1675, 1663, 1616, 1488, 1446, 761 cmꢀ1 1H NMR (400
;
In conclusion, we reported an efficient method for the synthesis
of chromenpyrimidines using the Co3O4/NiO@GQD@SO3H
nanocomposite as a superior catalyst under reux conditions.
The new catalyst was characterized via FT-IR, SEM, XRD, EDS,
TGA, BET and VSM. The current method provides obvious
advantages, including environmental friendliness, short reac-
tion time, reusability of the catalyst, low catalyst loading and
simple workup procedure.
MHz, DMSO-d6) d: 3.13 (s, 3H), 3.37 (s, 3H), 5.58 (s, 1H), 7.11–
7.84 (m, 10H), 13.97 (s, 1H, OH); 13C NMR (100 MHz, DMSO-d6)
d: 28.75, 31.17, 36.19, 86.95, 104.93, 116.63, 117.34, 124.22,
124.85, 128.40, 128.93, 130.79, 132.94, 138.08, 150.55, 152.42,
155.67, 164.28, 164.54, 166.16; anal. calcd for C22H18BrN3O5: C,
54.56%; H, 3.75%; N, 8.68%. Found: C, 54.62%; H, 3.83%; N,
8.75%.
6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)
(4-isopropylphenyl)
methyl)-1,3-dimethylpyrimidine-
ꢁ
2,4(1H,3H)-dione (4l). White solid; m.p. 257–259 C; IR (KBr):
Conflicts of interest
;
3463, 3230, 2958, 1695, 1671, 1616, 1569, 1446, 1343, 762 cmꢀ1
1H NMR (400 MHz, DMSO-d6) d: 1.15 (s, 6H), 2.77 (m, 1H), 3.15
There are no conicts to declare.
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 37344–37354 | 37353

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20 Y. Wang, Y. Shao, D. W. Matson, J. Li and Y. Lin, ACS Nano,
2010, 4, 1790–1798.
Acknowledgements
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The authors acknowledge a reviewer who provided helpful
insights. The authors are grateful to University of Kashan for
supporting this work by grant no.: 159196/XXI.
22 A. L. M. Reddy, A. Srivastava, S. R. Gowda, H. Gullapalli,
M. Dubey and P. M. Ajayan, ACS Nano, 2010, 4, 6337–6342.
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