One-Pot Synthesis of Dihydropyrimidinones/Thiones Catalyzed by White Marble a Metamorphic Rock: an Efficient and Reusable Catalyst for the Biginelli Reaction

Article abstract of DOI:10.1134/S0023158418030126

In this work, we report a simple, efficient and green protocol for the synthesis of dihydropyrimidinones/thiones (products of Biginelli reaction) by the use of white marble as an effective heterogeneous catalyst. Short reaction times, high product yields,

Full text of DOI:10.1134/S0023158418030126

ISSN 0023-1584, Kinetics and Catalysis, 2018, Vol. 59, No. 3, pp. 290–295. © Pleiades Publishing, Ltd., 2018.
One-Pot Synthesis of Dihydropyrimidinones/Thiones Catalyzed
by White Marble a Metamorphic Rock: an Efficient and Reusable
Catalyst for the Biginelli Reaction1
K. El Mejdoubia, *, B. Salleka, **, H. Cherkaouia, H. Chaairb, and H. Oudadessec
aLaboratory of Agroressources, Polymers and Process Engineering, Faculty of Sciences,
Ibn Tofaïl University, Kenitra, 14000 Morocco
bLaboratory of Processes Engineering, Faculty of Science and Techniques Mohammedia, Mohammedia, Morocco
cInstitute of Chemical Sciences of Rennes UMR CNRS 6226, University of Rennes, 1, France
*e-mail: elmejdoubi1989@gmail.com
**e-mail: brahimsallek@gmail.com
Received July 26, 2017
Abstract⎯In this work, we report a simple, efficient and green protocol for the synthesis of dihydropyrimid-
inones/thiones (products of Biginelli reaction) by the use of white marble as an effective heterogeneous cat-
alyst. Short reaction times, high product yields, simple processing procedure and reusability of the catalyst
are the superior characteristics of this protocol.
Keywords: Biginelli reaction, 3,4-dihydropyrimidin-2(1H)-ones/thiones, white marble, green catalyst
DOI: 10.1134/S0023158418030126
INTRODUCTION
Recently, several synthetic methods for the prepa-
ration of dihydropyrimidinones to improve the effi-
ciency of this reaction have been reported. These cat-
alytic systems involve Mn (OAc)3 ⋅ 2H2O [8], trifluo-
roacetic acid [9], boric acid [10], CeCl3 ⋅ 7H2O [11],
copper(II) triflate [12], LiBr [13], silica/sulfuric acid
[14], zinc triflate [15], I2 [16], bismuth triflate [17],
LiClO4 [18], NH4Cl [19], ZrCl4 [20], Fe(OTs)3 ⋅ 6H2O
[21], Yb(OTf)3 [22], benzyltriethylammonium chlo-
ride [23], AlCl3 : ZnCl2 (3 : 1) [24], etidronic acid [25].
In the concept of green chemistry, which is linked
to a desire of scientists to take preventive and sustain-
able action on the environment, research has been
developed for the application of new heterogeneous
natural catalysts [1, 2], in the synthesis of therapeutic
chemicals or key intermediates in the manufacturing
of pharmaceutical chemicals.
The dihydropyrimidinone derivatives known as
“Biginelli compounds” constitute an important class
of compounds exhibiting broad range of pharmaco-
logical and biological activities such as inhibitors of
the calcic channels, antihypertensive agents, antioxi-
dants, anti-tumor activity, anti-cancer and anti-
inflammatory drugs [3–6]. The Biginelli reaction
reported by the chemist P. Biginelli in 1893 involves
the condensation of three components: a β-ketoester
(ethyl acetoacetate) with an aldehyde and urea (or
thiourea) under strongly acidic conditions [7]. This
method of synthesis suffers however from disadvan-
tages such as low yields in the case of certain substi-
tuted aliphatic and aromatic aldehydes with a long
reaction time.
However, most of these methods suffer from one
disadvantage or another, such as the use of dangerous
and carcinogenic solvents, high catalyst loading or not
recoverable catalysts that sometimes contain toxic
metals. Therefore, there is a great need for new cata-
lytic processes which do not have these problems.
In this paper we would like to point out our work on
white marble (WM) to catalyze the synthesis reaction
of dihydropyrimidinones with great efficiency and
excellent reusability. The catalyst can be easily recov-
ered and still retains its catalytic activity.
We have shown that white marble could be consid-
ered as a new heterogeneous catalyst for the Biginelli
reaction.
1
The article is published in the original.
290

ONE-POT SYNTHESIS OF DIHYDROPYRIMIDINONES/THIONES CATALYZED
291
Transmittance, %
Intenisity, count
150000
1.0
0.8
0.6
0.4
0.2
0
100000
50000
0
10
20
30
40
50
60
70
2θ, deg
4000 3500 3000 2500 2000 1500 1000 500
Wavenumber, cm–1
Fig. 2. XRD pattern of marble powder.
Fig. 1. FT-IR spectrum of marble powder.
FT-IR reveals several bands, in particular those
MATERIALS AND METHODS
attributable to carbonate ions CO32− (Fig. 1). We have
thus identified the adsorption bands characteristic of
carbonates at 1480, 870 and 713 cm–1. Analysis of the
X-ray powder diffraction pattern (Fig. 2) showed a
well-crystallized phase. The presence of calcite was
confirmed by the characteristic 104 and 113 reflec-
tions at 29.41° and 39.39° (2θ) (Joint Committee on
Powder Diffraction International Centre for Diffrac-
tion Data Further (JCPDS: 86-2334). Note the
absence of the characteristic reflections of calcium
carbonate in the different allotropes aragonite
(JCPDS: 76-0606) and vaterite (JCPDS: 74-1867)
[26–30].
Characterization of the Catalyst:
Marble Powder
The marble powder used as a basic precursor in the
preparation of catalysts is the waste from the marble
works due to the cutting of white marble pieces. A
sample was subjected to a treatment consisting of
washing with water and ethanol followed by prelimi-
nary sieving to remove the impurities. After this oper-
ation, the grinding is carried out with sieving which
makes it possible to retain the granulometry of the car-
bonate at a size between 63 and 125 μm. The carbonate
thus obtained is dried and preserved at 100°C in the
oven.
The elemental analysis of the main constituent ele-
ments of the same samples was determined by EDS.
Table 1 gives the mineralogical composition of the
powder of marble used in this study. The powder of
marble has an average specific surface area of
4.23 m2/g as measured by the BET method.
The recovered after treatment powder have been
characterized by Fourier transform infrared spectros-
copy (FT-IR), X-ray diffraction (XRD), the elemental
analysis by energy dispersion spectroscopy (EDS)
using a fluorescence X spectrometer and by measuring
the specific surface.
General Procedure for the Synthesis
of Dihydropyrimidinones/Thiones
Table 1. Mineralogical composition of marble powder
Compound
Concentration, %
In a conventional procedure, ethyl acetoacetate
(1 mmol), aldehyde (1 mmol) and urea or thiourea
(1.5 mmol) were mixed with WM as a catalyst (10 mol %,
0.01 g) and heated to reflux in the presence of ethanol
(3 mL) as a solvent for an appropriate time. The prog-
ress of the reaction was monitored by TLC. After com-
pletion of the reaction, the catalyst was recovered by
filtration. The filtrate was evaporated and the crude
product purified by recrystallization from ethanol to
give the pure product. The products were identified by
comparison with melting points of the authentic com-
pounds, and by 1H and 13C NMR.
CaO
P2O5
F
SiO2
SO3
78
0.156
3.08
0.397
0.143
0.0874
0.195
1.11
Na2O
Al2O3
MgO
Fe2O3
0.0723
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EL MEJDOUBI et al.
Table 2. Effect of WM mass on condensation reaction of 1a,
2 and 3*
5-(Ethoxycarbonyl)-4-(4-nitrophenyl)-6-methyl-
3,4-dihydropyrimidin-2(1H)-one (4d). 1H NMR
(300 MHz, DMSO-d6), δ, ppm: 9.32 (s, 1H, NH),
8.18–8.21 (d, 2H, ArH), 7.87 (s, 1H, NH), 7.47–7.50
(d, 2H, ArH), 5.26 (d, 1H, CH), 4.00 (q, 2H, OCH2),
Catalyst,
mol %
Entry
Time, min
Yield, %**
1
2
3
4
5
6
7
–
10
20
30
40
480
45
45
45
45
45
45
No reaction
2.25 (s, 3H, CH3), 1.09 (t, 3H, OCH2CH3). 13C NMR
(300 MHz, DMSO-d6), δ, ppm: 165.52, 152.46,
152.21, 149.86, 147.18, 128.12, 124.30, 98.64, 59.86,
54.15, 18.33, 14.51.
93
86
80
72
65
48
5-(Ethoxycarbonyl)-6-methyl-4-phenyl-3,4-dihy-
dropyrimidin-2(1H)-thione (4e). 1H NMR (300 MHz,
DMSO-d6), δ, ppm: 10.31 (s, 1H, NH), 9.64 (s, 1H,
NH), 7.19–7.35 (m, 5H, ArH), 5.17 (d, 1H, CH), 4.02
(q, 2H, OCH2), 2.28 (s, 3H, CH3), 1.10 (t, 3H,
50
100
* Reaction conditions: 1a (1 mmol), 2 (1 mmol), 3 (1.5 mmol),
catalyst, EtOH (3 mL), 80°C, for 45 min.
** Isolated yield.
OCH2CH3). 13C NMR (300 MHz, DMSO-d6), δ,
ppm: 174.71, 165.59, 145.49, 143.96, 129.02, 128.14,
126.85, 101.19, 60.05, 54.51, 17.63, 14.47.
Spectral Data of Typical Compounds
5-(Ethoxycarbonyl)-4-(4-methoxyphenyl)-6-methyl-
3,4-dihydropyrimidin-2(1H)-thione (4f). 1H NMR
(300 MHz, DMSO-d6), δ, ppm: 10.27 (s, 1H, NH),
9.58 (s, 1H, NH), 6.86–7.43 (m, 4H, ArH), 5.10 (s,
1H, CH), 4.01 (q, 2H, OCH2), 3.70 (s, 3H, OCH3),
5-(Ethoxycarbonyl)-6-methyl-4-phenyl-3,4-dihy-
1
dropyrimidin-2(1H)-one (4a). H NMR (300 MHz,
DMSO-d6), δ, ppm: 9.17 (s, 1H, NH), 7.73 (s, 1H,
NH), 7.21–7.33 (m, 5H, ArH), 5.14 (d, 1H, CH), 4.00
(q, 2H, OCH2), 2.23 (s, 3H, CH3), 1.09 (t, 3H,
2.26 (s, 3H, CH3), 1.11 (t, 3H, OCH2CH3). 13C NMR
(300 MHz, DMSO-d6), δ, ppm: 174.48, 165.63,
159.20, 145.21, 136.16, 128.08, 114.34, 101.42, 60.00,
55.56, 53.90, 17.60, 14.49.
OCH2CH3). 13C NMR (300 MHz, DMSO-d6), δ,
ppm: 165.80, 152.62, 148.81, 145.33, 128.85, 127.72,
126.71, 99.74, 59.65, 54.44, 18.24, 14.53.
5-(Ethoxycarbonyl)-4-(4-chlorophenyl)-6-methyl-
3,4-dihydropyrimidin-2(1H)-one (4b). 1H NMR
(300 MHz, DMSO-d6), δ, ppm: 9.22 (s, 1H, NH),
7.76 (s, 1H, NH), 7.21–7.38 (m, 4H, ArH), 5.13 (d,
1H, CH), 3.99 (q, 2H, OCH2), 2.23 (s, 3H, CH3), 1.09
RESULTS AND DISCUSSION
Evaluation of the Catalytic Activity of WM
in the Synthesis of Dihydropyrimidinones
13
(t, 3H, OCH2CH3). C NMR (300 MHz, DMSO-
d6), δ, ppm: 165.67, 152.41, 149.19, 144.25, 132.25,
128.86, 128.65, 99.30, 59.72, 53.88, 18.26, 14.53.
5-(Ethoxycarbonyl)-6-methyl-4-(p-tolyl)-3,4-dihy-
Initial studies were realized using the benzaldehyde
(1 mmol), ethyl acetoacetate (1 mmol) and urea
(1.5 mmol) as the model reaction (Scheme 1). The
reaction was carried out in EtOH at 80°C with a differ-
ent catalyst mass. The best yield (93%) was obtained
1
dropyrimidin-2(1H)-one (4c). H NMR (300 MHz,
DMSO-d6), δ, ppm: 9.13 (s, 1H, NH), 9.12 (s, 1H,
NH), 7.65–7.67 (m, 4H, ArH), 5.09 (d, 1H, CH), using 10 mol % of the catalyst after 45 min (Table 2).
3.99 (q, 2H, OCH2), 3.31 (s, 3H, CH3), 2.21 (s, 3H,
In addition, the experiment was also carried out under
identical reaction conditions without the catalyst, no
trace of the product was found after 480 min. It was
evident that MW was the most effective catalyst
among of the catalysts tested.
CH3), 1.09 (t, 3H, OCH2CH3). 13C NMR (300 MHz,
DMSO-d6), δ, ppm: 165.82, 152.63, 148.61, 142.42,
136.82, 129.35, 126.61, 99.88, 59.62, 54.09, 21.11,
18.22, 14.56.
H3C
CHO
O
O
O
WM
+
+
H2N
NH2 EtOH, reflux
EtO
H3C
NH
O
OEt
N
H
O
1a
2
3
4a
Scheme 1. The model reaction between benzaldehyde (1a), ethyl acetoacetate (2) and urea (3) in the presence of catalyst.
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ONE-POT SYNTHESIS OF DIHYDROPYRIMIDINONES/THIONES CATALYZED
293
Table 3. Effect of different solvents on the synthesis of dihy-
dropyrimidinone (4a) catalyzed by WM*
Effect of Solvents
The effect of various solvents (such as MeOH,
EtOH, AcOEt, CH2Cl2, CH3CN, THF, CHCl3, and
1,4-dioxane) on the model reaction was studied in the
presence of WM (10 mol %). The results indicate that
the solvents had a significant effect on the yield of the
product. The use of dioxane, AcOEt and CHCl3 as
solvent resulted in low yields (Table 3, entries 5, 7 and
10). Solvents such as H2O, CH3CN, tetrahydrofuran
(THF) and CH2Cl2 gave moderate yields (Table 3,
entries 4, 6, 8 and 9). The best conversion was
observed when the reaction was carried out in ethanol
(Table 3, entry 2). On the basis of these results, EtOH
was then selected as a solvent for other investigations.
Entry
Solvent
Time, min
Yield, %**
1
2
3
No solvent
EtOH
MeOH
H2O
60
45
45
45
45
45
45
45
45
45
66
93
81
68
49
64
52
73
69
41
4
5
6
Dioxane
CH3CN
AcOEt
THF
CH2Cl2
CHCl3
7
8
9
10
* Reaction conditions: 1a (1 mmol), 2 (1 mmol), 3 (1.5 mmol),
catalyst (10 mol %), EtOH (3 mL), 80°C, for 45 min.
Time Effect of the Reaction
** Isolated yield.
To study the effect of the reaction time (Table 4),
the catalyst mass of 0.01 g (10 mol %) was chosen as
the optimum mass in the presence of EtOH as solvent.
The reaction mixture at 80°C for a short reaction time
(45 min) gave 93% of 4a (Table 4, entry 6). However,
when the reaction time was increased, the yield of the
4a started to decrease.
Table 4. Effect of reaction time on the yield of dihydropy-
rimidinone (4a) in the presence of WM*
Entry
Time, min
Yield, %**
1
2
3
4
5
6
7
8
3
5
12
23
57
68
86
93
81
75
Study of the Reusability of the Catalyst
10
15
30
45
60
120
To accomplish this study, we examined the reuse of
the catalyst. Indeed, a heterogeneous catalyst is not
considered interesting in organic synthesis if it can be
easily recovered and reused.
After completion of the reaction between benzal-
dehyde, ethyl acetoacetate and urea, the catalyst was
recovered by simple filtration and then washed with
water and ethanol (2 × 5 mL) to remove any trace of
reagents and final products adsorbed on the catalyst,
then dried in an oven at 80°C. The catalyst was reused
directly in the model reaction without any additional
* Reaction conditions: 1a (1 mmol), 2 (1 mmol), 3 (1.5 mmol),
catalyst, EtOH (3 mL), 80°C, for specified time.
** Isolated yield.
treatments. The efficiency of the recovered catalyst Table 5. Reusability of WM in the synthesis of 3,4-dihydro-
pyrimidinones*
was measured again by using the same reaction model.
As shown in Table 5, the reaction yield reached >80%
after 5 cycles. To the best of our knowledge, the reuse
of this catalyst is significantly better than that for most
supported catalysts reported.
Number
of recycling Time, min
runs
Entry
Yield, %**
1
2
3
4
5
1
2
3
4
5
45
45
45
45
45
93
93
91
89
86
Generalization
Using the optimum conditions, we have extended this
study with various aldehydes, ethyl acetoacetate and urea
or thiourea for the synthesis of a variety of 3,4-dihydro-
pyrimidin-2(1H)-one derivatives/thiones (Scheme 2).
The relevant data are presented in Table 6. The reactions
gave the desired products with satisfactory yields (88–
96%) depending on the substrate and the conditions used
for the reaction (Table 6, entries 1–6).
* Reaction conditions: 1a (1 mmol), 2a (1 mmol) and 3a
(1.5 mmol), catalyst (0.01 g), EtOH (3 mL), 80°C, for 45 min.
** Isolated yield.
KINETICS AND CATALYSIS Vol. 59 No. 3 2018

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EL MEJDOUBI et al.
R
H3C
OEt
CHO
X
O
O
WM (10 mol %)
NH2 EtOH, reflux
+
+
H2N
EtO
H3C
NH
R
O
N
H
X
1a−f
2
3
4a−f
Scheme 2. Generalization of the synthesis of dihydropyrimidinones/thiones.
Comparison of the Catalytic Activity
of WM and Other Catalysts
To establish the catalytic activity of the WM, we
compared the results obtained on the synthesis of 3,4- time compared to other reported systems [34–41].
dihydropyrimidinones with the literature data (Table 7).
Based on this comparison, we see that the used cata-
lyst (WM) presents higher yields and shorter reaction
Table 6. Synthesis of dihydropyrimidinones/thiones from various aromatic aldehydes with ethyl acetoacetate and urea or
thiourea catalyzed by WM
M.p., °C
Entry
Product
R
X
Time, min
Yield, %*
found
reported
1
2
3
4
5
6
4a
4b
4c
4d
4e
4f
H
4-Cl
4-Me
O
O
O
O
S
45
35
55
50
40
25
93
89
90
96
88
91
204–206
210–212
214–218
210–214
208–210
150–154
207–208 [31]
212–214 [32]
216–218 [32]
211–212 [32]
206–208 [31]
153 [33]
4-NO2
H
4-MeO
S
* Isolated yield.
Table 7. Comparison of the efficiency of WM with certain catalysts reported in the literature
Number
of recycling
runs
Reaction
time, h
Entry
Catalyst
Reaction conditions
Yield, %
Reference
1
2
3
4
5
WM (10%)
PS-PEG-SO3H (0.3 g)
Montmorillonite KSF (15%) H2O/100°C
Ethanol/100°C
Dioxane/2-propanol/80°C Not studied
5 (93–86%)
0.75
10
48
93
80
78
91
70
This study
[34]
Not studied
Not studied
6 (94–85%)
[35]
[14]
[36]
Silica-sulfuric acid (35%)
Molybdophosphoric acid
(2%)
Ethanol/reflux
AcOH/reflux
6
4
0.6
10
6
6
7
8
9
Fe3O4@Silica sulfuric acid
No solvent/80°C
4 (92–81%)
Not studied
7 (85–70%)
92
70
85
[37]
[38]
[39]
(0.05 g)
Triphenylphosphine (PPh3) No solvent/100°C
(10 mol %)
Fe3O4@mesoporous SBA-15 Ethanol/r.t.
(50 mg)
SiO2-Cl (2.5 mol %)
No solvent/80°C
No solvent/70°C
Not studied
6 (94–60%)
88
94
[40]
[41]
3
5.3
10 ASA NPs (10 mol %)
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ONE-POT SYNTHESIS OF DIHYDROPYRIMIDINONES/THIONES CATALYZED
295
19. Shaabani, A., Bazgir, A., and Teimouri, F., Tetrahedron
Lett., 2003, vol. 44, p. 857.
CONCLUSIONS
In conclusion, we used the white marble as a new
heterogeneous and effective catalyst in the reaction of
Biginelli for the synthesis of 3,4-dihydropyrimidin-2-
(1H)-ones and their analogues (thiones) by cyclocon-
densation of aldehydes, urea/thiouria and ethyl aceto-
acetate in ethanol. The WM showed a high reactivity
with 82–96% conversion in 15–45 min at reflux for
the various dihydropyrimidinone/thiones in 3 mL of
ethanol. In addition, this method offers several advan-
tages, including mild reaction conditions, low catalyst
loading, short reaction times, and high yields. The cat-
alyst can be recovered and reused up to 6 times without
significant loss of activity.
20. Reddy, C.V., Mahesh, M., Raju, P.V.K., Babu, T.R.,
and Reddy, V.V.N., Tetrahedron Lett., 2002, vol. 43,
p. 2657.
21. Starcevich, J.T., Laughlin, J.T., and Mohan, R.S., Tet-
rahedron Lett., 2013, vol. 54, p. 983.
22. Kang, S., Coopera, G., Dunned, S. F., Luand, C.H.,
Surmeier, J. D., and Silverman, R. B., Bioorg. Med.
Chem., 2013, vol. 21, p. 4365.
23. Bose, D.S., Sudharshan, M., and Chavhan, S.W.,
ARKIVOC, 2005, vol. 3, p. 228.
24. Balalaie, S., Soleiman-Beigi, M., and Rominger, F.J.,
J. Iran. Chem. Soc., 2005, vol. 2, p. 319.
25. Pansuriya, A.M., Savant, M.M., Bhuva, C.V., Singh, J.,
and Naliapara, Y.T., ARKIVOC, 2009, vol. VII, p. 79.
REFERENCES
26. Ren, M., Dong, Ch., and An, Ch., Materials, 2011,
1. Benzekri, Z., Serrar, H., Boukhris, S., Sallek, B., and
vol. 4, p. 1375.
Souizi, A., Curr. Chem. Lett., 2016, vol. 5, p. 99.
27. Hu, Z. and Deng, Y., Powder Technol., 2004. vol. 140,
2. El Mejdoubi, K., Bahammou, R., Benzekri, Z., Sallek,
B., Cherkaoui, H., and Boukhris, S., Int. J. Sci. Eng.
Res., 2017, vol. 8, N 1, p. 419.
p. 10.
28. Nurul Islam, Kh., Eaqub Ali, Md., Zuki Bin Abu
Bakar, Md., Loqman, M.Y., Islam, A., Saiful Islam, Md.,
Mahfujur Rahman, Md., and Ullah, M., Powder Tech-
nol., 2013, vol. 246, p. 434.
3. Lal, J., Gupta, S.K., Thavaselvam, D., and Agarwal, D.D.,
Med. Chem. Lett., 2012, vol. 22, p. 2872.
4. Wan, J.P., Mini.-Rev. Med. Chem., 2012, vol. 12, p. 337.
5. Wan, J.P. and Liu, Y., Synthesis, 2010, vol. 23, p. 3943.
29. Chen, J. and Xiang, L., Powder Technol., 2009, vol. 189,
p. 64.
6. Narahari, S.R., Reguri, B.R., Gudaparthi, O., and 30. Ma, H.Y. and Lee, I.S., Mater. Sci. Eng., C, 2006, vol.
Mukkanti, K., Tetrahedron Lett., 2012, vol. 53, p. 1543.
7. Biginelli, P., Gazz. Chim. Ital., 1893, vol. 23, p. 360.
26, p. 721.
31. Mobinikhaledi, A., Foroughifar, N., and Khajeh-
Amiri, A., React. Kinet. Mech. Catal., 2015, vol. 117,
p. 59.
8. Kumar, K.A., Kasthuraiah, M., Reddy, C.S., and
Reddy, C.D., Tetrahedron Lett., 2001, vol. 42, p. 7873.
32. Zare, A. and Nasouri, Z., J. Mol. Liq., 2016, vol. 216,
9. Bussolari, J.C. and McDonnel, P.A., J. Org. Chem.,
p. 364.
2000, vol. 65, p. 6777.
33. Javidi, J., Esmaeilpour, M., and Dodeji, F.N., RSC
Adv., 2015, vol. 5, N 1, p. 308.
10. Tu, S., Fang, F., Miao, C., Jiang, H., Feng, Y., Shi, D.,
and Wang, X., Tetrahedron Lett., 2003, vol. 44, p. 6153.
34. Quan, Z.J., Da, Y.X., Zhang, Z., and Wang, X.C.,
11. Bose, D.S., Fatima, L., Miao, C., Jiang, H., Feng, Y.,
Shi, D., and Wang, X.J., Org. Chem., 2003, vol. 68,
p. 587.
Catal. Commun., 2009, vol. 10, p. 1146.
35. Bigi, F., Carloni, S., Frullanti, B., Maggi, R., and Sar-
tori, G., Tetrahedron Lett., 1999, vol. 40, p. 3465.
12. Paraskar, A.S., Dewkar, G.K., and Sudalai, A., Tetra-
hedron Lett., 2003, vol. 44, p. 3305.
36. Heravi, M.M., Bakhtiari, K., and Bamoharram, F.F.,
Catal. Commun., 2006, vol. 7, p. 376.
13. Maiti, G., Kundu, P., and Guin, C., Tetrahedron Lett.,
2003, vol. 44, p. 2757.
37. Ali Reza, K. and Davarpanah, J., Res. Chem. Intermed.,
2015, vol. 41, no. 5, p. 2991.
14. Salehi, P., Dabiri, M., Zolfigol, M.A., and Bodaghi
Fard, M.A., Tetrahedron Lett., 2003, vol. 44, p. 2889.
38. Debache, A., Amimour, M., Belfaitah, A., Rhouati, S.,
and Carboni, B., Tetrahedron Lett., 2008, vol. 49,
p. 6119.
15. Xu, H. and Wang, Y., Chin. J. Chem., 2003, vol. 21,
p. 327.
39. Mondal, J., Sen, T., and Bhaumik, A., Dalton
Trans., 2012, vol. 41, p. 6173.
16. Srinivas, K.V.N. and Das, B., Synthesis, 2004, vol. 13,
p. 2091.
40. Karade, H.N., Sathe, M., and Kaushik, M.P.,
17. Varala, R., Alam, M.M., and Adapa, S.R., Synlett,
Mol., 2007, vol. 12, p. 1341.
2003, vol. 1, p. 67.
18. Yadav, J.S., Reddy, B.V.S., Srinivas, R., Venugopal, C., 41. Nasr-Esfahani, M. and Taei, M., RSC Adv., 2015,
and Ramalingam, T., Synthesis, 2001, vol. 9, p. 1341.
vol. 5, p. 44978.
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