Nano-copper chromite (nano-CuCr2O4): a novel and efficient catalyst for the synthesis of biscoumarin and pyrano[c]chromene derivatives in water at room temperature

Article abstract of DOI:10.1007/s11164-015-2305-x

A clean, efficient and eco-friendly procedure has been developed using nano-copper chromite (nano-CuCr₂O₄) as catalyst for the synthesis of biscoumarin and dihydropyrano[c]chromene derivatives. This method provides several advantages

Full text of DOI:10.1007/s11164-015-2305-x

Res Chem Intermed
DOI 10.1007/s11164-015-2305-x
Nano-copper chromite (nano-CuCr2O4): a novel
and efficient catalyst for the synthesis of biscoumarin
and pyrano[c]chromene derivatives in water at room
temperature
Zahed Karimi-Jaberi1 Mohammad Sadegh Moaddeli1
•
•
Moslem Setoodehkhah2 Mohammad Reza Nazarifar1
•
Received: 27 June 2015 / Accepted: 28 September 2015
Ó Springer Science+Business Media Dordrecht 2015
Abstract A clean, efficient and eco-friendly procedure has been developed using
nano-copper chromite (nano-CuCr2O4) as catalyst for the synthesis of biscoumarin
and dihydropyrano[c]chromene derivatives. This method provides several advan-
tages such as mild reaction conditions, simple work-up procedure and is environ-
ment friendly. In addition, water is chosen as a green solvent.
Keywords Dihydropyrano[c]chromenes Á Biscoumarin Á Malononitrile Á
Nano-copper chromite
Introduction
It is known that coumarin derivatives are very useful compounds. They have been
widely used as medicine intermediates due to their useful biological and
pharmacological properties, such as anticoagulant, spasmolytic, diuretic, and
anticancer [1–4]. Biscoumarin can be employed as a urease inhibitor material [5].
Furthermore, dihydropyrano[3,2-c]chromenes and their derivatives are of consid-
erable interest as they possess a wide range of biological properties, such as anti-
Alzheimer’s disease, anti-AIDS-associated dementia and anti-schizophrenia [6].
Therefore, their synthesis has attracted much attention over the past decades.
Numerous methods have been adapted to synthesize dihydropyrano[c]chromenes
[6–14] and biscoumarin [15–19].
The use of water as a green solvent is emphasized in green chemical processes,
because of the special properties of water, such as abundance, inexpensive,
&
Zahed Karimi-Jaberi
zahed.karimi@yahoo.com
1
2
Department of Chemistry, Firoozabad Branch, Islamic Azad University, Firoozabad, Fars, Iran
Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan,
P.O Box 87317-51167, Kashan, I. R. Iran
123

Z. Karimi-Jaberi et al.
environmentally benign, hydrogen bonding in the transition state and high cohesive
energy density, as well as negative activation volume. In addition, work-up and
purification can be carried out by simple phase separation techniques [20]. For these
reasons, the synthesis of heterocyclic compounds using multi-component protocols
in water has been much investigated in recent years [21].
Mixed oxides with spinel structure (AB2O4) are important inorganic metalloid
materials which are non-toxic, inexpensive, and very stable materials with strong
resistance to acids and alkalis, while their nanoparticles possess relatively high
surface areas. These properties make them suitable for use as solid heterogeneous
catalysts for organic transformations [22]. One of them, copper chromite nanopar-
ticles (CuCr2O4), has been used as a versatile catalyst in numerous reactions, for
example, the oxyamination of benzene to aniline [23], the hydroxylation of benzene
to phenol [24] and the synthesis of pyrazol derivatives [25].
In view of our ongoing efforts to explore newer reactions for the synthesis of
heterocyclic systems [26–28], we would like to report here the one-pot synthesis of
biscoumarin and 3,4-dihydropyrano[c]chromene derivatives by a three-component
reaction in aqueous media.
Experimental
All reagents were purchased from Merck, Fluka and Aldrich with high-grade
quality, and used without any purification. Copper chromite nanoparticles were
successfully synthesized by coprecipitation according to the reported method [29].
X-ray diffraction (XRD) analyses of the samples were carried out with a Philips
˚
Xpert Pro using Cu Ka (k = 1.5406 A). Scanning electron microscopy (SEM)
microstructure analyses were carried out with a Vega 435 Vpi linked to an energy
dispersive X-ray microanalysis system.
Representative procedure for the synthesis of dihydropyrano
[3,2-c]chromene derivatives
A solution of aromatic aldehyde (1 mmol), malononitrile (1.2 mmol), 4-hydroxy-
coumarin (1 mmol), and nano-CuCr2O4 (10 mol%) in 5.0 mL water was stirred at
room temperature for the appropriate times (Table 1). Completion of the reaction
Table 1 Optimization of catalyst loading for the three-component reaction of 4-hydroxycoumarin,
malononitrile and 4-chlorobenzaldehyde
Enrty
Catalysts
Time (min)
Yields (%)
1
2
3
4
5
Catalysts-free
10 h
100
2
10
60
80
95
95
CuCr2O4 (10 mol%)
Nano-CuCr2O4 (5 mol%)
Nano-CuCr2O4 (10 mol%)
Nano-CuCr2O4 (15 mol%)
2
2
Reaction conditions: 4-chlorobenzaldehyde (1 mmol), malononitrile (1.2 mmol), 4-hydroxycoumarin
(1 mmol), in water at room temperature
123

Nano copper chromite (nano CuCr2O4): A novel and…
was monitored by TLC. The solid was filtered off and washed with water
(2 9 20 mL) and purified by recrystallization from ethanol. The product was
dissolved in acetone and the catalyst was separated by filtration (Tables 2, 3). The
physical data (mp, IR, NMR) of known compounds were found to be identical with
those reported in the literature.
Table 2 Synthesis of 3,4-dihydropyrano[c]chromenes using nano-CuCr2O4 (10 mol%)
Entry
Ar
Product
Time
(min)
Yield
(%)a
m.p. (°C)
Observed
From the literature
(References)
1
C6H5
4a
4b
4c
4d
4e
4f
6
6
4
3
5
2
2
2
5
4
3
5
4
88
87
90
90
89
98
97
95
89
97
94
97
96
256–258
250–252
260–262
249–251
285–286
259–261
258–260
259–261
263–265
281–283
257–259
264–266
274–276
256–258 [6]
251–253 [8]
260–262 [8]
247–249 [8]
284–286 [6]
258–260 [7]
260–262 [7]
263–264 [9]
263–264 [9]
282–283 [9]
257–259 [10]
262–266 [10]
274–276 [10]
2
4-CH3C6H4
4-FC6H4
3
4
4-BrC6H4
4-CNC6H4
3-O2NC6H4
4-O2NC6H4
4-ClC6H4
2-ClC6H4
2,3-ClC6H3
2,4-ClC6H3
4-OHC6H4
2-OCH3C6H4
5
6
7
4g
4h
4i
8
9
10
11
12
13
a
4j
4k
4l
4m
Yields refer to the isolated pure products. All the desired product(s) were characterized by a comparison
of their physical and spectroscopic data with those of known compounds
Table 3 Comparison of the efficiency of nano-CuCr2O4 with other catalysts for the synthesis 3,4-
dihydropyrano[c]chromene derivatives
Entry Conditions
Time
(min)
Yield
(%)
References
1
2
3
(NH4)2HPO4 (10 mol%), H2O/EtOH (1:1), r.t.
4 h
81–95
72–88
86–90
[6]
[6]
[7]
(S)-Proline (10 mol%), H2O/EtOH (1:1), Reflux
3 h
H6[P2W18O62]Á18H2O (1 mol%), H2O/EtOH (1:1),
30–85
Reflux
4
5
6
Sodium dodecyl sulfate (20 mol%), H2O, 60 °C
[H3NCH2CH2OH][CH3COO], pulverize
Nano-CuCr2O4 (10 mol%), r.t.
2–3 h
8–14
2–6
78–96
71–95
87–98
[8]
[9]
–
123

Z. Karimi-Jaberi et al.
Representative procedure for the synthesis of a, a0-benzylidene bis(4-
hydroxycoumarin) derivatives
A solution of aromatic aldehyde (1 mmol), 4-hydroxycoumarin (2 mmol), and
nano-CuCr2O4 (10 mol%) in 5.0 mL water was stirred at room temperature for the
appropriate times (Table 4). Completion of the reaction was monitored by TLC. The
solid was filtered off and washed with water (2 9 20 mL) and purified by
recrystallization from ethanol. The product was dissolved in acetone and the catalyst
was separated by filtration.
1
The structures of all products were confirmed by IR, HNMR, 13CNMR, and
elemental analysis.
Spectral data of products
2-Amino-4-phenyl-4, 5-dihydro-5-oxopyrano[3,2-c]chromene-3-carbonitrile (4a) 1H
NMR (400 MHz, DMSO-d6): d = 4.46 (1H, s, CH), 7.25 (2H, d, J = 8 Hz, ArH), 7.28
(1H, s, ArH), 7.33 (2H, t, J = 8 Hz, ArH), 7.43 (2H, s, NH2), 7.46–7.52 (2H, m, ArH),
7.72 (1H, t, J = 8 Hz, ArH), 7.91 (1H, d, J = 8 Hz, ArH) ppm. IR(KBr): 3380, 3291,
2196, 1705, 1671, 1599, 1527, 1374 cm-1
.
2-Amino-4-(4-fluorophenyl)-4, 5-dihydro-5-oxopyrano[3,2-c]chromene-3-carboni-
trile (4c) 1H NMR (400 MHz, DMSO-d6): d = 4.49 (1H, s, CH), 7.14 (2H, t,
J = 8 Hz, ArH), 7.33 (2H, t, J = 8 Hz, ArH), 7.44 (2H, s, NH2), 7.45 (1H, d,
J = 8 Hz, ArH), 7.48 (1H, t, J = 8 Hz, ArH), 7.70 (1H, t, J = 8 Hz, ArH), 7.90
(1H, d, J = 8 Hz, ArH) ppm. IR(KBr): 3380, 3293, 2194, 1717, 1677, 1605, 1506,
1379 cm-1
.
2-Amino-4-(4-nitrophenyl)-4, 5-dihydro-5-oxopyrano[3,2-c]chromene-3-carboni-
trile (4g) 1H NMR (250 MHz, DMSO-d6): d = 4.68 (1H, s, CH), 7.22–7.59
(5H, m, ArH), 7.62 (2H, s, NH2), 7.71–7.77 (1H, m, ArH), 7.90–7.93 (1H, m, ArH),
Table 4 Synthesis of a,a0-benzylidene bis(4-hydroxycoumarin)s
Entry
Ar
Product
Time (min)
Yield (%)
m.p. (°C)
obsd.
Lit. [References]
1
2
C6H5
5a
5b
5c
5d
5e
5f
4
3
3
2
3
3
1
1
2
2
89
88
84
95
96
95
99
98
98
96
230–232
265–267
246–248
211–212
264–266
242–244
232–234
229–231
256–258
269–270
227–229 [16]
266–268 [8]
242–244 [16]
213–215 [8]
265–267 [8]
240–242 [16]
232–234 [8]
234–236 [8]
254–256 [19]
–
4-CH3C6H4
4-OCH3C6H4
4-FC6H4
3
4
5
4-BrC6H4
4-CNC6H4
4-O2NC6H4
3-O2NC6H4
4-ClC6H4
4-Cl-3-NO2
6
7
5g
5h
5i
8
9
10
5j
123

Nano copper chromite (nano CuCr2O4): A novel and…
8.18 (2H, d, J = 8 Hz, ArH) ppm. IR(KBr): 3400, 3300, 2198, 1707, 1670, 1596,
1491, 1373 cm-1
.
2-Amino-4-(4-cholorophenyl)-4,
5-dihydro-5-oxopyrano[3,2-c]chromene-3-car-
bonitrile (4h) 1H NMR (250 MHz, DMSO-d6): d = 4.46 (1H, s, CH),
7.27–7.36 (4H, m, ArH), 7.44 (2H, s, NH2), 7.49 (2H, s, ArH), 7.70 (1H, t,
J = 7.5 Hz, ArH), 7.88 (1H, d, J = 7.5 Hz, ArH) ppm. IR(KBr): 3390, 3300, 2199,
1710, 1670, 1603, 1512, 1371 cm-1
.
2-Amino-4-(2, 3-dichlorophenyl)-4, 5-dihydro-5-oxopyrano[3,2-c]chromene-3-car-
bonitrile (4j) 1H NMR (400 MHz, DMSO-d6): d = 5.09 (1H, s, CH), 7.28–7.35
(3H, m, ArH), 7.49 (1H, d, J = 8 Hz, ArH), 7.52 (2H, s, NH2), 7.55 (1H, d, J = 8
ArH), 7.74 (1H, t, J = 8 Hz, ArH), 7.92 (1H, d, J = 8 Hz, ArH) ppm. IR(KBr):
3380, 3291, 2196, 1705, 1671, 1599, 1527, 1374 cm-1
.
3,30-(4-Methoxybenzylidene)-bis-(4-hydroxycoumarin) (5c) 1H NMR (400 MHz,
DMSO-d6) d: 3.71 (3H, s, CH3O), 6.31 (1H, s, CH), 6.80–7.93 (12H, m, ArH),
8.16–8.78 (2H, m, OH) ppm. IR(KBr): 3443, 2926, 1668, 1606, 1563, 1510, 1452,
1352, 767 cm-1
.
3,30-(3-Nitrobenzylidene)-bis-(4-hydroxycoumarin) (5h) 1H NMR (400 MHz,
DMSO-d6) d: 6.39 (1H, s, CH), 7.28–8.04 (12H, m, ArH), 8.04–9.52 (2H, m,
OH) ppm. IR(KBr): 3424, 2925, 1655, 1616, 1564, 1494, 1450, 1347, 762 cm-1
.
3,30-(4-Cholorobenzylidene)-bis-(4-hydroxycoumarin) (5i) 1H NMR (400 MHz,
DMSO-d6) d: 6.63 (1H, s, CH), 7.16–7.90 (12H, m, ArH), 7.90–9 (2H, m, OH) ppm.
IR(KBr): 3420, 2923, 1668, 1606, 1563, 1490, 1451, 1351, 765 cm-1
.
3,30-(4-Choloro 3-nitrobenzylidene)-bis-(4-hydroxycoumarin) (5j) 1H NMR
(400 MHz, DMSO-d6) d: 6.28 (1H, s, CH), 7.26–7.85 (11H, m, ArH), 8.15–8.56
(2H, m, OH); 13C NMR (DMSO-d6) d: 36.42, 103.23, 116.24, 119.31, 121.99,
123.81, 124.03, 124.51, 131.39, 132.07, 132.89, 143.87, 147.94, 152.90, 164.70,
167.34 ppm. IR(KBr): 3423, 2920, 1665, 1613, 1558, 1536, 1450, 1348, 765 cm-1
.
Anal. Calcd For C25H16ClNO8: C, 60.80; H, 3.27; N, 2.84; Found: C, 60.89; H, 3.25;
N, 2.90.
Results and discussion
In the preliminary experiments, copper chromite nanoparticles were successfully
synthesized by the coprecipitation method and were characterized by XRD analysis
and SEM. X-ray diffraction patterns of the sample synthesized at Cu/Cr = 0.5 and
pH values of 9 are presented in Fig. 1. The main peak is at 2h = 35.4°, which is
referred to the plane, and clearly indicates the formation of CuCr2O4. The results
indicated that the samples have been composed of CuCr2O4 spinel and CuO phases.
The wide diffraction peaks are indicative of a very fine particle size of the sample.
123

Z. Karimi-Jaberi et al.
Fig. 1 The XRD pattern of CuCr2O4 nanoparticles
The samples were analyzed by X-ray dispersive analysis (EDX) and the results
are shown in Fig. 2. It can be seen that all the samples exhibit assignments of Cu, Cr
and O.
The SEM micrograph of the nanocatalyst is shown in Fig. 3. The micrograph of
the sample exhibits particles of irregular shape and sizes of particles varying from
20 to 30 nm. Large aggregates of nanoparticles are clearly present in the sample,
because of the very small size of the particles.
In the first instance, the reaction of 4-chlorobenzaldehyde, malononitrile and
4-hydroxycoumarin was explored using copper chromite (nano-CuCr2O4) as
catalyst to afford the corresponding dihydropyranochromene product. The best
results were obtained by carrying out the reaction at room temperature for 2 min
with 10 mol% nano-copper chromite as a catalyst in aqueous media and a molar
ratio of 4-chlorobenzaldehyde/malononitrile/4-hydroxycoumarin of 1:1.2:1.
In addition, we also studied the influence of the amount of nano-CuCr2O4 on the
reaction yield. It was found that the nano-CuCr2O4 plays a crucial role in the success
of the reaction in terms of the rate and the yields. For example, the reaction could be
carried out in the absence of nano-CuCr2O4 in water at room temperature for 10 h,
but it produced a very poor yield (Table 1, entry 1). The best catalytic activity of
nano-CuCr2O4 was optimized to be 10 mol% (Table 1, entry 4). The excessive
amounts of catalyst do not increase the yield significantly. Furthermore, to elucidate
the role of the nanoparticle size effect, the CuCr2O4 nanoparticle catalyst was
replaced by a CuCr2O4 catalyst with larger particle size at the optimum reaction
conditions (Table 1, entry 2). In this experiment, the yield of the product was very
modest even with a prolonged reaction time, indicating that the particle size has a
considerable influence on the catalyst reactivity.
123

Nano copper chromite (nano CuCr2O4): A novel and…
Fig. 2 EDX pattern sample
Fig. 3 SEM image of sample
These results promoted us to investigate the scope and generality of this three-
component protocol using various aldehydes under optimized conditions
(Scheme 1). The results are summarized in Table 2. In all these cases, the
corresponding dihydropyranochromene derivatives were obtained in good yields.
123

Z. Karimi-Jaberi et al.
NH2
CN
OH
O
O
1
Ar
nano CuCr2O4
H2O, r.t.
CN
+
+
Ar
H
CN
2
O
3
O
O
4
O
Scheme 1 Synthesis of dihydropyrano[c]chromenes
As shown in Table 2, we can find a series of aromatic aldehyde were reacted with
malononitrile, and 4-hydroxycoumarin in the presence of nano-CuCr2O4 in water at
room temperature, the reaction proceeded smoothly to afford the corresponding
products 4 in good yields. All aromatic aldehydes containing electron-withdrawing
groups (such as the nitro group, halides) or electron-donating groups (such as the
alkyl group) were employed and reacted well to give the corresponding product 4 in
good to excellent yields under these reaction conditions, so we conclude that no
obvious effect of electrons or the nature of the substituents on the aromatic ring
were observed. We also found that the reaction did not proceed in the case in which
aliphatic aldehyde was used. The reason we think is that the activity of aliphatic
aldehydes is less than that of aromatic aldehydes.
Some of the reported results for this reaction are summarized in Table 3 to
compare with our results. The data indicated that the nano-CuCr2O4 is the most
suitable for this reaction.
Under the same reaction conditions, nano-CuCr2O4 was also found to efficiently
catalyze the one-pot condensation of 4-hydroxycoumarin and aromatic aldehydes in
neat water at room temperature, high yields of products 5 were found (Scheme 2).
The results are summarized in Table 4.
Benzaldehyde and other aromatic aldehydes containing electron-with drawing
groups (such as the nitro group, halides) and 4-hydroxycoumarin were employed
under this reaction condition to afford the corresponding products with good yields
(84–98 %) in Table 4. The reactions of aromatic aldehydes containing electron-
donating groups (such as the alkyl group) with 4-hydroxycoumarin can also give the
corresponding products in good yields (84–88 %). The property of substituents on
the aromatic ring did not show strongly obvious effects in terms of yields under this
reaction condition.
Table 5 gives the details about the catalytic activity of some other reported
protocols in the synthesis of a,a0-benzylidenebis(4-hydroxycoumarin) derivatives.
Table 6 demonstrates that nano-CuCr2O4 can act as an effective catalyst in
comparison with other catalysts.
It was apparent that this method can accelerate this reaction using nano-CuCr2O4
as a catalyst under solvent-free conditions in neat water at room temperature.
It is noteworthy that the catalyst is recyclable and could be reused without any
significant loss of activity. In the case of the model reaction in water, after five runs,
the catalytic activity of the catalyst was almost the same as that of the freshly used
catalyst (Table 6).
123

Nano copper chromite (nano CuCr2O4): A novel and…
Ar
OH
OH
O
OH
O
O
nano CuCr2O4
+
H2O, r.t.
Ar
H
O
O
O
O
1
3
5
Scheme 2 Synthesis of a,a0-benzylidene bis(4-hydroxycoumarin)s
Table 5 Comparison results of nano-CuCr2O4 with other catalysts reported in the literature
Entry Conditions Time (min) Yield (%) References
1
2
3
4
5
6
Sodium dodecyl sulfate (20 mol%), H2O, 60 °C
H2O, MWI, 150 °C
[MIM(CH2)4SO3H] (20 mol%), solvent-free, 80 °C
[Bmim]BF4 (4 mmol), solvent-free, 60–70 °C
Starch–sulfuric acid, (5 mol%), 80 °C
Nano-CuCr2O4 (10 mol%), H2O, r.t.
2.5–3 h
8–10
80–96
76–94
86–96
77–91
80–95
83–98
[8]
[15]
[17]
[18]
[19]
–
25–30
2–3 h
5–12
1–4
Table 6 Reusability of the catalysts in the model reactiona,b
Entry
Number of recycle
Yield (%)a
Yield (%)b
1
2
3
4
5
6
a
First
95
95
93
92
90
89
98
98
97
95
92
90
1
2
3
4
5
Reaction conditions: 4-chlorobenzaldehyde (5 mmol), malononitrile (6 mmol), 4-hydroxycoumarin
(5 mmol), nano-CuCr2O4 (10 mol%), water (25 mL), at room temperature
b
Reaction conditions: 4-chlorobenzaldehyde (5 mmol), 4-hydroxycoumarin (10 mmol), nano-CuCr2O4
(10 mol%), water (25 mL), at room temperature
Conclusion
In conclusion, nano-CuCr2O4 was found to be a novel alternative catalyst for the
synthesis of benzylidene bis(4-hydroxycoumarin) and dihydropyrano[c]chromene
derivatives in water at room temperature. The simple experimental procedure,
environmentally friendly process, short reaction times, excellent yields and
reusability of the catalyst make this procedure facile, practical and sustainable.
123

Z. Karimi-Jaberi et al.
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