Molybdate sulfuric acid-catalyzed one-pot synthesis of substituted coumarins under solvent-free conditions

Article abstract of DOI:10.1007/s11164-014-1810-7

An efficient method for the synthesis of new aryloylamido coumarins via a one-pot, three-component reaction of an aryl glyoxal, benzamide, and a 4-hydroxycoumarin in the presence of molybdate sulfuric acid under solvent-free conditions is reported. This h

Full text of DOI:10.1007/s11164-014-1810-7

Res Chem Intermed
DOI 10.1007/s11164-014-1810-7
Molybdate sulfuric acid-catalyzed one-pot synthesis
of substituted coumarins under solvent-free conditions
•
Saeed Khodabakhshi Bahador Karami
Khalil Eskandari
•
Received: 23 June 2014 / Accepted: 11 September 2014
Ó Springer Science+Business Media Dordrecht 2014
Abstract An efficient method for the synthesis of new aryloylamido coumarins
via a one-pot, three-component reaction of an aryl glyoxal, benzamide, and a
4-hydroxycoumarin in the presence of molybdate sulfuric acid under solvent-free
conditions is reported. This high yielding reaction is in accordance with green
chemistry aspects.
Keywords Aryloylamido coumarins Á Aryl glyoxal Á Benzamide Á
4-Hydroxycoumarin
Introduction
Coumarin and its derivatives have become well known because of their interesting
biological and photodynamic properties [1, 2]. The development of efficient and
concise strategies that allow access to functionalized coumarins is an important task
in modern organic chemistry [3–5]. For example, some substituted 4-hydrox-
ycoumarins at the 3-position have been found in a fascinating array of bioactive
natural products and pharmaceutical compounds. Dicoumarol and warfarin are
vitamin K antagonists which play an anticoagulant role in the treatment of
thromboembolic disorders (Fig. 1) [6, 7].
S. Khodabakhshi (&)
Young Researchers and Elite Club, Gachsaran Branch, Islamic Azad University, Gachsaran, Iran
e-mail: saeidkhm@yahoo.com
B. Karami
Department of Chemistry, Yasouj University, P.O. Box 353, 75918-74831 Yasouj, Iran
K. Eskandari
Young Researchers and Elite Club, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran
123

S. Khodabakhshi et al.
O
HO
OH
H3C
OH
O
O
O
O
O
O
Warfarin
Fig. 1 Coumarin derivatives as vitamin K antagonists
Dicoumarol
To date, some multicomponent synthetic methodologies have been reported for
the preparation of arylamino/amido coumarins [8, 9]. One-pot and multicomponent
reactions (MCRs) have drawn special attention due to the advent of high-throughput
screening techniques that have enabled rapid identification of potential new
medicines among large collections of organic compounds [10, 11]. In addition, the
continual insistence on development of facile, convenient, and nonpolluting
synthetic procedures has persuaded chemists to update their science and increase
their potency with respect to green chemistry factors. In relation to this, solid-phase
reactions have attracted remarkable attention in the synthetic community and have
proved to be promising conditions in organic synthesis due to their economic and
environmentally friendly nature. In addition, if the catalyst is recyclable, this would
improve both the environmental impact and the economic profile of the method
[12–14]. In this paper, we wish to report the one-pot synthesis of some aryloylamido
coumarins using molybdate sulfuric acid (MSA) as a recyclable catalyst under
solvent-free conditions.
Experimental
General
Commercially available reagents were purchased from Merck. Aryl glyoxals were
prepared in accordance with previous literature [15]. MSA was prepared based on
our previous report [16]. Melting points were measured on an elecrtothermal
KSB1N apparatus. IR spectra were recorded in the matrix of KBr with JASCO FT-
1
IR-680 plus spectrometer. H NMR and 13C NMR spectra were recorded on a FT-
NMR Bruker Avance Ultra Shield Spectrometer at 400.13 and 100.62 MHz in
DMSO-d6 as solvent. Elemental analyses (C, H, N) were performed with a Heraeus
CHN-O-Rapid analyzer. The results agreed favorably with the calculated values.
TLC was performed on TLC-Grade silica gel-G/UV 254 nm plates.
General procedure for the synthesis of 4
A mixture of aryl glyoxal (1 mmol), benzamide (1.1 mmol), and MSA (5 mol%)
was stirred and heated at 80 °C for 30 min. Then, the 4-hydroxycoumarin was
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Molybdate sulfuric acid-catalyzed one-pot synthesis
added and the reaction stirred until completion. The reaction progress was
monitored by TLC (EtOAc/Hexane, 1:1). After completion, the mixture was washed
with MeOH. The precipitate was dissolved in hot EtOH:THF (3/1) and the catalyst
was separated. The purification by silica gel column chromatography using
n-hexane–EtOAc (1:1) as an eluent is needed to obtain pure product.
Spectral data
Compound 4a
Mp. 220–224 °C. IR (KBr): 3,347, 2,924, 1,687, 1,613, 1,565, 1,492, 1,344,
1,260 cm-1 1H NMR (400 MHz, DMSO-d6): d = 8.55 (s, 1H), 7.90 (d, 1H,
.
J = 7.6 Hz), 7.84–7.78 (m, 4H), 7.42 (t, 1H, J = 7.6 Hz), 7.50–7.38 (m, 6H), 7.29
(t, 2H, J = 7.6 Hz), 6.64 (d, 1H, J = 6.4 Hz). 13C NMR (100 MHz, DMSO-d6):
d = 196.4, 165.3, 162.3, 160.5, 151.34, 134.2, 132.3, 131.8, 130.5, 130.4, 127.4,
127.2, 127.1, 126.3, 123.0, 122.7, 115.3, 114.8, 101.0, 52.2. Anal. Calcd for
C24H17NO5: C, 72.17; H, 4.29; N, 3.51. Found: C, 72.28; H, 4.10; N, 3.58.
Compound 4b
Mp. 248–250 °C. IR (KBr) v~ = 3,373, 3,064, 2,926, 1,688, 1,614, 1,599, 1,566,
1,345, 1,227, 1,159 cm-1 1H NMR (DMSO-d6, 400 MHz): d = 8.79 (d, 1H,
.
J = 6.8 Hz), 8.03 (d, 1H, J = 7.2 Hz), 7.97–7.91 (m, 4H), 7.67 (t, 1H, J = 7.2 Hz),
7.58 (t, 1H, J = 7.2 Hz), 7.49 (t, 2H, J = 7.6 Hz), 7.40 (t, 2H, J = 8.0 Hz), 7.32 (t,
2H, J = 8.8 Hz), 6.67 (s, 1H). 13C NMR (DMSO-d6, 100 MHz): d = 193.5, 167.0,
166.9, 163.8, 162.0, 152.9, 133.9 (d, J = 3.1 Hz), 133.5, 132.5, 132.1, 130.8 (d,
J = 9.3 Hz), 128.8, 128.0, 124.6, 124.3, 116.99, 116.1 (d, J = 22.3 Hz), 102.6,
52.8. Anal. Calcd for C24H16FNO5: C, 69.06; H, 3.86; N, 3.36. Found: C, 69.33; H,
3.76; N, 3.30.
Compound 4c
Mp. 243–245 °C. IR (KBr) v~ = 3,350, 3,061, 1,696, 1,615, 1,587, 1,565, 1,347,
1
1,222, 620 cm-1. H NMR (DMSO-d6, 400 MHz): d = 8.81 (d, 1H, J = 6.8 Hz),
8.03 (d, 1H, J = 7.6 Hz), 7.92 (d, 2H, J = 7.2 Hz), 7.80 (d, 2H, J = 8.4 Hz),
7.71–7.66 (m, 3H), 7.57 (t, 1H, J = 7.2 Hz), 7.49 (t, 2H, J = 7.6 Hz), 7.40 (t, 2H,
J = 7.6 Hz), 6.65 (s, 1H). 13C NMR (DMSO-d6, 100 MHz): d = 196.9, 167.1,
163.9, 162.1, 153.0, 134.9, 133.8, 133.5, 132.1, 129.9, 128.8, 128.0, 127.3, 124.7,
124.3, 116.9, 116.2, 102.7, 52.9. Anal. Calcd for C24H16BrNO5: C, 60.27; H, 3.37;
N, 2.93. Found: C, 60.39; H, 3.32; N, 2.70.
Compound 4d
Mp. 243–245 °C. IR (KBr) v~ = 3,377, 3,074, 1,701, 1,673, 1,613, 1,565, 1,523,
1,344, 1,222 cm-1. 1H NMR (DMSO-d6, 400 MHz): d = 8.85 (s, 1H), 8.30 (d, 2H,
J = 8.8 Hz), 8.09-7.92 (m, 5H), 7.66 (t, 1H, J = 7.6 Hz), 7.56 (t, 1H, J = 7.2 Hz),
123

S. Khodabakhshi et al.
7.48 (t, 2H, J = 7.2 Hz), 7.39 (t, 2H, J = 7.2 Hz), 6.69 (s, 1H). 13C NMR (DMSO-
d6, 100 MHz): d = 197.5, 167.1, 133.8, 133.6, 132.1, 129.2, 128.7, 128.0, 124.7,
124.2, 117.0, 101.9, 67.48. Anal. Calcd for C24H16N2O7: C, 64.87; H, 3.63; N, 6.30.
Found: C, 65.07; H, 3.70; N, 6.26.
Compound 4e
Mp. 218–220 °C. IR (KBr) v~ = 3,343, 3,069, 2,960, 1,692, 1,616, 1,600, 1,566,
1
1,261 cm-1. H NMR (DMSO-d6, 400 MHz): d = 8.73 (d, 1H, J = 7.2 Hz), 8.04
(dd, 1H, J1 = 8.4, J2 = 1.6 Hz), 7.92–7.86 (m, 4H), 7.69–7.65 (m, 1H), 760–7.56
(m, 1H), 7.50 (t, 2H, J = 7.6 Hz),7.42–7.38 (m, 2H), 7.01 (d, 2H), J = 8.8 Hz),
6.66 (m, 1H), 3.79 (s, 3H). 13C NMR (DMSO-d6, 100 MHz): d = 193.6, 167.0,
166.9, 163.5, 163.4, 162.0, 152.9, 133.9, 133.4, 132.1, 130.3, 128.8, 128.2, 127.9,
124.7, 124.3, 116.9, 116.2, 114.3, 103.2, 55.9, 52.5. Anal. Calcd for C25H19NO6: C,
69.92; H, 4.46; N, 3.26. Found: C, 70.02; H, 4.40; N, 3.29.
Compound 4f
Mp.[280 °C. IR (KBr) v~ = 3,412, 3,069, 2,938, 1,695, 1,626, 1,600, 1,536, 1,360,
1,267 cm-1 1H NMR (DMSO-d6, 400 MHz): d = 8.48 (d, 1H, J = 8.4 Hz),
.
7.90–7.85 (m, 3H), 7.71 (s, 1H), 7.65 (d, 1H, J = 8.0 Hz), 7.59–7.55 (m, 1H),
7.53–7.49 (m, 2H), 7.42–7.38 (m, 1H), 7.31 (t, 1H, J = 8.0 Hz), 7.16–7.12 (m, 1H),
7.09–7.05 (m, 2H), 6.75–6.72 (m, 1H), 3.78 (s, 3H). 13C NMR (DMSO-d6,
100 MHz): d = 196.3, 172.8, 166.5, 164.1, 159.3, 154.0, 137.3, 134.6, 132.0, 131.1,
129.7, 128.9, 127.6, 125.4, 122.8, 122.7, 120.7, 119.1, 116.1, 113.1, 96.0, 55.6,
53.4. Anal. Calcd for C25H19NO6: C, 69.92; H, 4.46; N, 3.26. Found: C, 69.98; H,
4.43; N, 3.20.
Compound 4g
Mp. 225–227 °C. IR (KBr) v~ = 3,230, 3,061, 2,938, 1,717, 1,673, 1,632, 1,602,
1,554, 1,225 cm-1. 1H NMR (DMSO-d6, 400 MHz): d = 8.78 (d, 1H, J = 6.8 Hz),
8.50 (d, 1H, J = 8.4 Hz), 8.04 (d, 1H, J = 8.4 Hz), 8.01–7.98 (m, 2H), 7.96–7.93
(m, 3H), 7.64–7.56 (m, 4H), 7.54–7.49 (m, 3H), 7.35 (t, 1H, J = 7.6 Hz), 7.29 (d,
1H, J = 8.4 Hz), 6.96 (s, 1H). 13C NMR (DMSO-d6, 100 MHz): d = 197.6, 167.3,
167.2, 163.6, 162.5, 152.7, 134.3, 133.9, 133.3, 132.6, 132.2, 130.4, 128.9, 128.7,
128.0, 127.8, 126.8, 126.4, 126.4, 124.8, 124.6, 124.3, 116.8, 116.1, 102.8, 53.9.
Anal. Calcd for C28H19NO5: C, 74.82; H, 4.26; N, 3.12. Found: C, 75.12; H, 4.15;
N, 3.01.
Compound 4h
Mp. 242–244 °C. IR (KBr) v~ = 3,329, 1,695, 1,671, 1,617, 1,568, 1,349,
1
1,041 cm-1. H NMR (DMSO-d6, 400 MHz): d = 8.85 (d, 1H, J = 6.8 Hz), 8.52
(s, 1H), 8.05–7.98 (m, 3H), 7.96-7.94 (m, 4H), 7.64 (t, 2H, J = 6.8 Hz), 7.60–7.56
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Molybdate sulfuric acid-catalyzed one-pot synthesis
(m, 2H), 7.50 (t, 2H, J = 7.6 Hz), 7.39–7.34 (m, 2H), 6.86 (s, 1H). 13C NMR
(DMSO-d6, 100 MHz): d = 195.5, 167.1, 163.7, 162.1, 152.9, 135.3, 133.9, 133.9,
133.4, 133.3, 132.3, 132.1, 129.8, 128.9, 128.8, 128.6, 128.1, 128.0, 127.5, 124.6,
124.3, 124.2, 116.9, 116.2, 102.8, 53.0. Anal. Calcd for C28H19NO5: C, 74.82; H,
4.26; N, 3.12. Found: C, 74.95; H, 4.17; N, 3.05.
Results and discussions
As part of an ongoing research program aiming to find novel methods within
organic chemistry, we have synthesized a small library consisting of some
heterocyclic compounds containing coumarin nucleus [17–19]. We report a simple
and facile procedure for the synthesis of aryloylamido coumarins 4 from the
reaction of aryl glyoxals 2, which in turn are obtained by selenium dioxide oxidation
of the corresponding aryl ketones 1 [20], with benzamide 2 and 4-hydroxycoumarin
3 under solvent-free conditions (Scheme 1).
It should be noted that the intermediate 1 was in situ-generated and the reactions
were performed efficiently via a one-pot method. In fact, in the first designation, we
were concerned about some limitations including the formation of probable
dicoumarols as the side product [21].
At the outset, to determine suitable reaction conditions, the reaction of phenyl
glyoxal with 2 and 3 was carried out as a model. In all cases, the reaction was
performed under solvent-free conditions. To find the best amount of catalyst, we
O
O
OH
O
HO
Ar
CH3
Ph
NH2
N
(i)
2
O
O
Ar
(ii)
H
1
Ar
Int. 1
OH
OH
H
O
O
O
N
3
(iii)
O
O
O
Ar
4
(i): SeO2, 1,4-Dioxan/H 2O
(ii): Solvent-free, MSA (5 mol%), 60 °C
(iii): Solvent-free, MSA (5 mol%), 80 °C
Scheme 1 Synthesis of aryloylamido coumarins using MSA
123

S. Khodabakhshi et al.
Fig. 2 Optimization of the catalyst amount in synthesis of 4a at 80 °C under solvent-free conditions
Fig. 3 Optimization of temperature in synthesis of 4a
screened the model reaction in the absence and presence of several amounts of
MSA. In the absence of the MSA, the model reaction could be carried out but the
product was obtained in very low yield after a long period of time. In the presence of
MSA, however, it was found that 5 mol% of MSA is optimal to carry out the
reaction in a short duration. Increasing the amount of catalyst did not markedly
affect the progress of the reaction (Fig. 2).
In another variation, various temperatures were investigated (Fig. 3). It was
observed that the reaction did not proceed at room temperature. The best result was
obtained when the temperature increased to 80 °C. Further increasing the
temperature led to undesired products and the yield was dramatically decreased.
After optimization of the reaction conditions, we employed different aryl
glyoxals to show the generality of the present method (Table 1).
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Molybdate sulfuric acid-catalyzed one-pot synthesis
Table 1 Synthesis of 4 using MSA as catalyst under solvent-free conditions
Entry
1
Ar
Product
Time (min)
120
Yield (%)a
80
C6H5
O
O
NH
OH
O
O
4a
2
4-F-C6H4
100
75
O
O
NH
OH
O
O
F
4b
3
4
5
4-Br-C6H4
110
120
90
80
77
80
O
O
NH
OH
O
O
4c
Br
4-NO2-C6H4
O
O
NH
OH
O
O
O2N
4d
4-MeO-C6H4
O
O
NH
O
OH
O
MeO
4e
123

S. Khodabakhshi et al.
Table 1 continued
Entry
6
Ar
Product
Time (min)
135
Yield (%)a
70
3-MeO-C6H4
O
O
NH
O
OH
O
OMe
4f
7
1-Naphthyl
120
85
O
O
NH
OH
O
O
4g
8
2-Naphthyl
90
87
O
O
NH
OH
O
O
4h
a
Isolated yield
1
All synthesized compounds (4a–h) were characterized by H and 13C NMR,
elemental analysis, and IR spectrometry. In these reactions, electron-rich and -
deficient aryl glyoxals worked well.
Chemical reactions in the absence of organic solvents, defined as solvent-free
reactions, obviously reduce pollution and cost due to simplification of experimental
procedure, work-up technique, and saving of labor [22]. The used catalyst (MSA) is
also safe and separable from the reaction mixture and is reusable for further
reactions [23–25]. Therefore, the efficiency of this strategy under environmentally
friendly conditions will clearly be in accordance with green chemistry principles. In
order to enhance the catalytic efficiency of the MSA and reduce waste, the
recyclability of the catalyst was also investigated. As shown in Fig. 4, it could be
seen that the catalyst remained active through at least 3 runs. After the product was
123

Molybdate sulfuric acid-catalyzed one-pot synthesis
Fig. 4 Recyclability of MSA in synthesis of 4a under optimized conditions. Reaction time: 120 min
removed from the catalyst using an organic solvent, the catalyst was reused directly
for the next time without further purification.
Conclusion
In summary, we have successfully developed a green, cost-effective and facile
method for the one-pot synthesis of some new substituted coumarins using MSA as
a safe and recyclable solid acid catalyst under solvent-free conditions. Some
interesting features are highlighted: high yields of products, operational simplicity,
avoidance of organic solvents, and novelty. It is important to mention that the
presence of transformable functionalities in the products makes them potentially
valuable for further synthetic manipulations.
Acknowledgments Financial support for this work by the research affairs, Yasouj University (Iran), is
gratefully acknowledged.
References
1. S.M. Sethna, N.M. Shah, Chem. Rev. 36, 1–62 (1945)
2. P.O. Patil, S.B. Bari, S.D. Firke, P.K. Deshmukh, S.T. Donda, D.A. Patil, Bioorg. Med. Chem. 21,
2434–2450 (2013)
3. G.H. Mahdavinia, S. Peikarporsan, Monatsh. Chem. 144, 415–419 (2013)
4. B. Karami, S. Khodabakhshi, K. Eskandari, Tetrahedron Lett. 53, 1445–1446 (2012)
5. S. Khodabakhshi, M. Baghernejad, J. Chin. Chem. Soc. 61, 521–524 (2014)
6. S. Khodabakhshi, B. Karami, M. Baghernejad, J. Chem. Res. 38, 356–357 (2014)
7. F. Jafari, S. Khodabakhshi, Bulgarian Chem. Commun. 46, 36–42 (2014)
8. A. Kumar, M.K. Gupta, M. Kumar, Tetrahedron Lett. 52, 4521–4632 (2011)
9. M. Anary-Abbasinejad, H. Anaraki-Ardakani, A. Hassanabadi, Synth. Commun. 38, 3706–3716
(2008)
123

S. Khodabakhshi et al.
10. N. Hazeri, M.T. Maghsoodlou, S.M. Habibi-Khorassani, J. Aboonajmi, M. Lashkari, S.S. Sajadikhah,
Res. Chem. Intermed. 40, 1781–1788 (2014)
11. B. Karami, K. Eskandari, S. Khodabakhshi, J. Iran. Chem. Soc. 11, 631–637 (2014)
12. H.R. Shaterian, F. Rigi, Res. Chem. Intermed. 40, 1997–2005 (2014)
13. G.R. Desiraju, Organic solid state chemistry (Elsevier, Amsterdam, 1987)
14. S. Khodabakhshi, B. Karami, Catal. Sci. Technol. 2, 1940–1944 (2012)
15. B. Karami, K. Eskandari, F. Hashemi, Tetrahedron Lett. 54, 3583–3585 (2013)
16. B. Karami, S. Khodabakhshi, M. Nikrooz, Polycycl. Aromat. Compd. 31, 97–109 (2011)
17. S. Khodabakhshi, B. Karami, K. Eskandari, C. R. Chimie 17, 35–40 (2014)
18. S. Khodabakhshi, B. Karami, K. Eskandari, M. Farahi, Tetrahedron Lett. 55, 3753–3755 (2014)
19. B. Karami, K. Eskandari, S. Khodabakhshi, S.J. Hoseini, F. Hashemian, RSC Adv. 3, 23335–23342
(2013)
20. S. Khodabakhshi, B. Karami, K. Eskandari, S.J. Hoseini, A. Rashidi, RSC Adv. 4, 17891–17895
(2014)
21. S. Khodabakhshi, Iran. J. Catal. 3, 67–71 (2013)
22. B. Karami, M. Taei, S. Khodabakhshi, M. Jamshidi, J. Sulfur Chem. 33, 65–74 (2012)
23. M. Montazerozohori, B. Karami, Helv. Chim. Acta 89, 2922–2926 (2006)
24. M. Montazerozohori, B. Karami, M. Azizi, Arkivoc 1, 99–104 (2007)
25. F. Tamaddon, H. Kargar-Shooroki, A.A. Jafari, J. Mol. Catal. A: Chemical 368, 66–71 (2013)
123