Studies on the synthesis of substituted 2-amino-4H-benzo[h]chromene and 3-amino-1H-benzo[f]chromene derivatives using base supported ionic liquid like-phase (SILLP) as an efficient green catalyst

Article abstract of DOI:10.3184/174751917X14815427219202

The synthesis of several substituted 2-amino-4H-benzo[h]chromene and 3-amino-1H-benzo[f]chromene derivatives was carried out using a one-pot three-component reaction of an arylaldehyde, malononitrile and a naphthol in H₂O and in the presence of

Full text of DOI:10.3184/174751917X14815427219202

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JOURNAL OF CHEMICAL RESEARCH 2016
VOL. 41 JANUARY, 21–24
RESEARCH PAPER 21
Studies on the synthesis of substituted 2-amino-4H-benzo[h]chromene and
3-amino-1H-benzo[f]chromene derivatives using base supported ionic liquid
like-phase (SILLP) as an efficient green catalyst
Leila Kheirkhaha, Manouchehr Mamaghania*, Nosrat Ollah Mahmoodia, Asieh Yahyazadeha and
Seyedeh Saeedeh Mirnezami Ziabarib
aDepartment of Chemistry, Faculty of Sciences, University of Guilan, PO Box 41335-1914, Rasht, Iran
bDepartment of Chemistry, Faculty of Sciences, Islamic Azad University, Rasht Branch, PO Box 41335-3516, Rasht, Iran
The synthesis of several substituted 2-amino-4H-benzo[h]chromene and 3-amino-1H-benzo[f]chromene derivatives was carried out using
a one-pot three-component reaction of an arylaldehyde, malononitrile and a naphthol in H2O and in the presence of recyclable base
supported ionic liquid like-phase as an efficient green catalyst.
Keywords: 2-aminobenzo[h]chromene, 3-aminobenzo[f]chromene, three-component reaction, base supported ionic liquid like-phase (SILLP), naphthol
2-Aminochromenes are an important class of heterocyclic
compounds with important biological activities and
pharmacological properties. Fused-ring chromenes are
biologically interesting compounds showing a wide spectrum
of activities, such as antimicrobial,1 mutagenicitical,2 mitogen-
activated protein kinase-activated protein kinase 2 inhibitory,3
antiproliferative,4 sex pheromonal,5 antitumoural6 and
antioxidant activities.7
abundant non-toxic chemical in nature. Aqua-mediated reactions
have received considerable attention in organic synthesis due to
environmental safety reasons. Reactions in aqueous media offer
many advantages, such as simple operation and high efficiency, in
many organic reactions that involve water soluble substrates and
reagents.14,15 These advantages become even more attractive if such
reactions can be conducted using ionic liquids in aqueous media.
Results and discussion
Traditional methods have been reported for the synthesis of
2-aminobenzo[h]chromene and 3-aminobenzo[f]chromene
derivatives by condensation of α-naphthol or β-naphthol, an
aldehyde and malononitrile using different homogeneous or
heterogeneous catalysts, such as cetyltrimethyl-ammonium
Ionic liquids have attracted increasing interest in the context of
green synthesis in recent years. They have a unique combination
of chemical and physical properties, including nonvolatility,
nonflammability, thermal stability and controlled miscibility.
They are the solvents of choice for a large array of organic
reactions and can perform as a catalyst at the same time.16–22
With respect to our continued interest in developing benign
methods for the synthesis of biologically important products,23–28
we report a simple and high-yielding protocol for the synthesis
of 2-amino-2-chromenes using SILLP as an efficient and
recyclable heterogeneous base catalyst (Scheme 1).
In a preliminary experiment, to optimise the reaction
conditions, SILLP was synthesised using Merrifield resin
(1% cross linked, 200–400 mesh, 1.0–1.3 mmol g−1) and
the procedure employed by Luis and coworkers.13 A one-
pot three-component reaction of equimolar amounts of
chloride/bromide,8,9
triethylbenzylammonium
chloride,10
tetrabutylammonium bromide11 and benzyl[2-(dimethylamino)
ethyl]dimethylammonium chloride.12 Although each of these
procedures has its own merits, some methods require the use of
a hazardous amine-based catalyst and expensive catalysts, and
have long reaction times, harsh reaction conditions, low yields,
tedious work-up processes, environmental disposal problems
or use organic solvents. Thus, we report a more convenient and
practical method for the syntheses of 2-aminobenzo[h]chromene
and 3-aminobenzo[f]chromene derivatives using base supported
ionic liquid like-phase (SILLP)13 as a recyclable solid supported
heterogeneous catalyst in water. Water is the cheapest and most
NH2
N
C
H
O
O
Ar
R1
SILLP
R1
3
N
N
C
5
ArCHO
1
H2O, reflux
H
O
C
N
C
Ar
NH2
R2
2
4
O
H
C
3
R2
H
O
N
6
N
H
C
3
ILLP
S
Ar = 4-ClC6H4, 4-BrC6H4, 3-BrC6H4, 4-MeC6H4, 4-MeOC6H4, 2-thienyl, 2-furyl, 2-O2NC6H4,
3-O2NC6H4, 4-O2NC6H4, 4-FC6H4,..
R1 = H, 4-Cl; R2 = H, 6-Br
Scheme 1 Synthesis of 2-amino- and 3-aminochromene derivatives using SILLP.
* Correspondent. E-mail: m-chem41@guilan.ac.ir; mchem41@gmail.com

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22 JOURNAL OF CHEMICAL RESEARCH 2016
4-chlorobenzaldehyde (1), malononitrile and α-naphthol in the
presence of SILLP (0.1 g mmol−1 substrate) in refluxing water
was selected as the model reaction. The reaction furnished
the desired 2-aminochromene 5a (Table 1, entry 1) in 80%
yield. The effect of various solvents, such as H2O, EtOH,
THF, CH3CN, CH2Cl2, DMF and 1,4-dioxane, and different
temperatures was also examined, with water selected as the
solvent of choice at refluxing temperature. Under optimised
conditions, various arylaldehydes and naphthol derivatives
were evaluated and the results are presented in Table 1. As
shown in Table 1, aromatic aldehydes with electron-donating
and electron-withdrawing groups were rapidly condensed with
malononitrile and various naphthols in the presence of SILLP
and afforded the corresponding aminochromenes in high yield
(80–97%) and short reaction time (10–20 min).
A plausible mechanism for the formation of products 5 and 6 is
presented in Scheme 2, which proceeds through a Knoevenagel
condensation of an arylaldehyde (1) and malononitrile (2)
followed by Michael addition of a naphthol (3 or 4) to furnish
the desired products.
Table 1 2-Aminochromene derivatives using SILLP under optimised conditions
Entry
1
Ar
Naphthol
Product
5a
5b
5c
5d
5e
5f
Time/min
18a
20a
15a
10a
15a
10a
20a
15a
10a
20a
10a
15a
10a
10a
12
Yield/%a,b
80
Melting point/°C
4-ClC6H4
4-O2NC6H4
4-BrC6H4
4-CH3OC6H4
4-CH3C6H4
C6H5
233–235 (lit.29 231–233)
239–241(lit.29 239.5–241)
255–257
α-naphthol
α-naphthol
α-naphthol
α-naphthol
α-naphthol
α-naphthol
2
82
3
85
4
87
195–197 (lit.30 195–196)
206–208 (lit.31 205–207)
222–224 (lit.32 218–219)
232–234 (lit.32 230–232)
215–217 (lit.29 214.5–216)
236–238
5
86
6
97
7
2-NO2C6H4
3-O2NC6H4
3-BrC6H4
4-FC6H4
3-O2NC6H4
4-O2NC6H4
2-thienyl
2-furyl
5g
5h
5i
94
α-naphthol
α-naphthol
α-naphthol
α-naphthol
4-chloro-α-naphthol
4-chloro-α-naphthol
4-chloro-α-naphthol
4-chloro-α-naphthol
α-naphthol
β-naphthol
β-naphthol
β-naphthol
β-naphthol
β-naphthol
6-bromo-β-naphthol
8
93
9
90
10
11
12
13
14
15
16
17
18
19
20
21
5j
93
231–233 (lit.32 234–236)
5k
5l
91
220–221
96
229–231
5m
5n
5o
6a
6b
6c
6d
6e
6f
91
235–236
90
227–229
2-furyl
87
170–171 (lit.32 169–172)
285–287 (lit.32 288–289)
230–232 (lit.32 232–233)
268–270 (lit.31 270–272)
224–226 (lit.32 225–226)
206–208 (lit.32 207–208.5)
197–199
C6H5
10a
12a
15a
10a
15
93
4-FC6H4
4-CH3C6H4
2-furyl
90
85
85
4-ClC6H4
4-O2NC6H4
83
13
81
aIsolated yield.
bRatio of aldehyde (1 mmol)/malononitrile (1 mmol)/naphthol (1 mmol)/SILLP (0.1 g); the reaction was accomplished in H2O at 100 °C.
H
C
3
N
H3C
N
OH
H
O
OH
H
C
3
N
N
H
C
N
R1
N
C
N
C
H
3
3
ArCHO
1
or
(SILLP)
CN
Ar
C
2
H
O
4
R2
N
C
NH2
N
CN
r
A
O
C
:
N
C
H
O
N
C
:
Ar
H
O
cyclisation
transfer
Ar
5
R1
or
H
or
R1
R2
CN
Ar
NH2
O
6
R2
Scheme 2 A plausible mechanism for the synthesis of 5a–o and 6a–f.

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JOURNAL OF CHEMICAL RESEARCH 2016 23
Table 2 Comparison of the efficiency of different catalysts in the
synthesis of 5f in refluxing H2O
DMSO-d6): δ 161.0, 145.9, 143.7, 133.6, 132.5, 130.8, 128.6, 127.7,
127.6, 126.9, 124.9, 123.6, 121.6, 121.2, 121.0 118.2, 56.7, 41.2. Anal.
calcd for C20H13BrN2O (377.23): C, 63.68; H, 3.47; N, 7.43; found: C,
63.49; H, 3.32; N, 7.28%.
Entry Ar
Catalyst
SILLP
[bmim]OHb
[bmim][PF6]c
CuSO4·5H2O
Time/min
10
60
120
60
Yield/%a
1
2
3
4
C6H5
97 (this work)
90 (lit.33)
86 (lit.34)
95 (lit.34)
2-Amino-4-(3-bromophenyl)-3-cyano-4H-benzo[h]chromene (5i):
White powder; IR (KBr) (nmax cm−1): 3445, 3334, 3190 (N–H), 2189
(C≡N), 1656 (C=C), 1016 (C–Br), 810, 756 (aromatic C–H bend);
1H NMR (500 MHz, DMSO-d6): δ 8.25 (1H, d, J = 8.4 Hz, ArH),
7.92 (d, J = 8.0 Hz, ArH), 7.68–7.58 (3H, m, ArH), 7.47–7.44 (2H, m,
ArH), 7.33–7.25 (2H, m, ArH), 7.15 (1H, d, J = 8.8 Hz, ArH), 4.98 (1H,
s, C–H); 13C NMR (100 MHz, DMSO-d6): δ 160.77, 160.73, 148.87,
143.26, 133.27, 131.51, 130.74, 130.40, 128.19, 127.39, 127.25, 126.50,
124.58, 123.22, 122.45, 121.23, 120.81, 117.68, 56.15, 40.88. Anal.
calcd for C20H13BrN2O (377.23): C, 63.68; H, 3.47; N, 7.43; found: C,
63.51; H, 3.28; N, 7.24%.
2-Amino-6-chloro-4-(3-nitrophenyl)-3-cyano-4H-benzo[h]
carbonitrile (5k): Yellow powder; IR (KBr) (nmax cm−1): 3369, 3315
(N–H), 2196 (C≡N), 1660 (C=C), 1529, 1352 (NO2), 857, 811, 762
(aromatic C–H bend); 1H NMR (400 MHz, DMSO-d6): δ 8.36 (1H,
m, ArH), 8.19 (1H, t, J =1.8, ArH), 8.16–8.12 (2H, m, ArH), 7.82–7.77
(3H, m, Ar–H), 7.67 (1H, t, J = 8.0 Hz, ArH), 7.44 (s, NH2), 7.40 (1H,
s, ArH), 5.22 (1H, s, C–H); 13C NMR (100 MHz, DMSO-d6): δ 160.7,
160.65, 148.5, 147.7, 142.7, 135.1, 131.0, 129.9, 128.9, 128.3, 126.4,
126.1, 124.4, 124.3, 122.8, 122.6, 122, 120.5, 117.9, 55.7. Anal. calcd for
C20H12ClN3O3 (377.78): C, 63.59; H, 3.20; N, 11.12; found: C, 63.43; H,
3.09; N, 11.04%.
C6H5
C6H5
C6H5
aIsolated yield.
b1-Butyl-3-methylimidazolium hydroxide.
c1-Butyl-3-methylimidazolium hexafluorophosphate.
The reusability of the catalyst in the abovementioned
reactions was also rechecked by using the preparation of 5a and
6a as model reactions. After five consecutive runs, the activity
of the catalyst remained almost unchanged. After each run, the
product mixture was dissolved in EtOH, the catalyst simply
filtered off, washed with EtOH, dried and reused for the next
four runs without appreciable loss of its catalytic activity.
To show the efficiency of the present method, we have
compared our results for the synthesis of 2-aminobenzo[h]
chromene 5f, catalysed by SILLP, with other reported protocols
in the literature. It is evident from the results in Table 2 that
the reaction in the presence of SILLP produces the product in a
much shorter reaction time and higher yield.
2-Amino-6-chloro-4-(4-nitrophenyl)-3-cyano-4H-benzo[h]
carbonitrile (5l): Yellow powder; IR (KBr) (nmax cm−1): 3445, 3325,
3202 (N–H), 2191 (C≡N), 1661 (C=C), 1514, 1348 (NO2), 1109 (C–
Conclusion
1
We have developed an efficient and eco-friendly protocol for
the one-pot three-component synthesis of 2-aminobenzo[h]
chromene and 3-aminobenzo[f]chromene derivatives using
SILLP. The catalyst is recoverable and the efficiency of the
catalyst remains almost unaltered after five cycles. Excellent
yields, simple workup, short reaction times, easy recovery of
the catalyst and the green nature of the procedure make this
methodology attractive for large-scale synthesis.
Cl), 874, 812, 758, 698 (aromatic C–H bend); H NMR (500 MHz,
DMSO-d6): δ 8.33 (d, J = 7.87 Hz, 1H, ArH), 8.17 (d, J = 8.80 Hz, 2H,
ArH), 8.03 (d, J = 8.50 Hz, 1H, ArH), 7.75–7.68 (m, 2H, ArH), 7.55
(d, J = 8.80 Hz, 2H, ArH), 7.42 (s, 2H, NH2), 7.27 (s, 1H, ArH), 5.13
(s, 1H, C–H); 13C NMR (125 MHz, DMSO-d6): δ 161.0, 153.2, 147.5,
143.2, 130.4, 129.9, 129.3, 128.7, 126.8, 126.5, 125.0, 124.8, 124.7,
122.4, 120.8, 118.0, 56.0, 41.2. Anal. calcd for C20H12ClN3O3 (377.78):
C, 63.59; H, 3.20; N, 11.12; found: C, 63.40; H, 3.02; N, 11.01%.
2-Amino-6-chloro-4-(thiophen-2-yl)-4H-benzo[h]chromene-3-
carbonitrile (5m): White powder; IR (KBr) (nmax cm−1): 3445, 3325
(N–H), 2195 (C≡N), 1664 (C=C), 761 (C–S), 802, 761, 705 (aromatic
C–H bend); 1H NMR (400 MHz, DMSO-d6): δ 8.32 (1H, m, ArH),
8.14 (1H, m, ArH), 7.79 (2H, m, ArH), 7.49 (1H, s, ArH), 7.43 (1H, dd,
J =1.2, 5.2 Hz, ArH), 7.44 (1H, s, ArH), 7.36 (s, NH2), 7.16 (1H, dd, ,
J = 0.8, 3.6 Hz, ArH), 6.99 (1H, dd, J = 3.6, 5.2 Hz, ArH), 5.32 (1H, s,);
13C NMR (100 MHz, DMSO-d6): δ 160.5, 160.4, 150.6, 142.1, 129.8,
128.8, 128.2, 127.5, 126.3, 126.2, 126.16, 125.4, 124.33 124.3, 121.9,
120.6, 118.8, 56.8. Anal. calcd for C18H11ClN2OS (338.81): C, 63.81; H,
3.27; N, 8.27; found: C, 63.72; H, 3.11; N, 8.09.
2-Amino-6-chloro-4-(furan-2-yl)-4H-benzo[h]chromene-3-
carbonitrile (5n): White powder; IR (KBr) (nmax cm−1): 3449, 3330
(N–H), 2186 (C≡N), 1658 (C=C), 1257 (C–O), 857, 758, 734 (aromatic
C–H bend); 1H NMR (400 MHz, DMSO-d6): δ 8.31 (1H, m, ArH), 8.15
(1H, m, ArH), 7.78 (2H, m, ArH), 7.57 (1H, dd, J = 1.0, 1.8 Hz, ArH),
7.44 (1H, s, ArH), 7.34 (s, NH2), 6.41 (1H, dd, J = 1.6, 3.2 Hz, ArH), 6.31
(1H, d, J = 3.2 Hz, ArH), 5.11 (1H, s);13C NMR (100 MHz, DMSO-d6):
δ 161.1, 161.1, 156.2, 143.4, 142.9, 129.9, 128.8, 126.1, 124.4, 124.3, 121.8,
120.5, 116.5, 111.0, 107.0, 53.5. Anal. calcd for C18H11ClN2O2 (322.75): C,
66.99; H, 3.44; N, 8.68; found: C, 66.85; H, 3.31; N, 8.52%.
Experimental
Melting points were measured on an Electrothermal 9100 apparatus.
IR spectra were determined on a Shimadzo IR-470 spectrometer.
1H NMR and 13C NMR spectra were recorded on a 400 and 500 MHz
Bruker DRX-400 with DMSO-d6 as solvent and TMS as an internal
standard. Chemical shifts are expressed in ppm downfield from TMS.
Elemental analyses were performed on a Carlo-Erba EA1110CNNO-S
analyser and agreed (within 0.2%) with the calculated values. All
chemicals were purchased from Merck and used without further
purification. All solvents used were dried and distilled according to
standard procedures.
Synthesis of 2-amino-4H-benzo[h]chromene and 3-amino-1H-
benzo[f]chromene derivatives (5a–o, 6a–f); general procedure
A mixture of benzaldehyde 1 (1 mmol), malononitrile 2 (1 mmol),
α-naphthol 3 (1 mmol) or β-naphthol (4) and SILLP (0.1 g) in water (5
mL) were refluxed for a certain time (monitored by TLC), and the solid
product was dissolved in EtOH and filtered off to remove the catalyst.
The catalyst was washed with EtOH and the combined organic
solution was evaporated under reduced pressure to produce the desired
products. The crude products were purified by recrystallisation from
DMF–H2O and washing with cold ethanol. The catalyst was dried and
reused for four runs without appreciable loss of its catalytic activity.
2-Amino-4-(4-bromophenyl)-3-cyano-4H-benzo[h]chromene (5c):
White powder; IR (KBr) (nmax cm−1): 3450, 3333, 3198 (N–H), 2179
(C≡N), 1662 (C=C), 1012 (C–Br), 806, 758 (aromatic C–H bend);
1H NMR (500 MHz, DMSO-d6): δ 8.25 (1H, d, J = 8.32 Hz, ArH),
7.88 (1H, d, J = 8.08 Hz, ArH), 7.63 (1H, t, J = 7.58 Hz, ArH), 7.59
(1H, d, J = 8.52 Hz, ArH), 7.56 (1H, t, J = 7.02 Hz, ArH), 7.50 (2H, d,
J = 8.34 Hz, ArH), 7.21 (2H, d, J = 8.34 Hz, ArH), 7.20 (2H, s, NH2),
7.08 (1H, d, J = 8.52 Hz, ArH), 4.93 (1H, s, C–H);13C NMR (100 MHz,
3-Amino-8-bromo-2-cyano-1- (4-nitrophenyl)-1H-benzo[f]
chromene (6f): Yellow powder; IR (KBr) (nmax cm−1): 3391, 3325, 3200
(N–H), 2191 (C≡N), 1653 (C=C), 1520, 1346 (NO2), 1086 (C–Br),
1
840, 827 (aromatic C–H bend); H NMR (500 MHz, CDCl3): δ 7.69
(2H, d, J = 8.28 Hz, ArH), 7.55 (1H, s, ArH), 7.33 (1H, d, J = 8.96 Hz
ArH), 7.03 (1H, d, J = 8.88 Hz, ArH), 6.96 (1H, d, J = 8.96 Hz, ArH),
6.90–6.84 (3H, m, ArH), 4.87 (1H, s, C–H), 4.50 (2H, s, NH2);
13C NMR (100 MHz, CDCl3): δ 163.1, 159.3, 151.4, 147.8, 147.4, 133.0,
131.3, 131.2, 129.8, 129.4, 128.5, 125.3, 124.9, 119.9, 118.4, 114.2, 60.7,
39.1. Anal. calcd for C20H12BrN3O3 (422.23): C, 56.89; H, 2.86; N, 9.95;
found: C, 56.74; H, 2.75; N, 9.82.

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24 JOURNAL OF CHEMICAL RESEARCH 2016
12 C. Lu, X.J. Huang, Y.Q. Li, M.Y. Zhou and W. Zheng, Monatsh. Chem.,
2009, 140, 45.
13 M.I. Burguete, H. Erytropel, E.G. Verdugo, S.V. Luis and V. Sans, Green
Chem., 2008, 10, 401.
Acknowledgements
The authors are grateful to the Research Council of University
of Guilan.
14 C. Li, J. Chem. Rev., 2005, 105, 3095.
15 W. Wei, C.J. Li and R.S. Varma, Clean Tech. Environ. Policy, 2005, 7, 62.
16 C.E. Song, Chem. Commun., 2004, 1033.
17 J. Dupont, R.F. de Souza and P.A. Suarez, Chem. Rev., 2002, 102, 3667.
18 H. Oliver-Bourbigou and L. Magna, J. Mol. Catal. A: Chem., 2002, 419,
182.
19 A.R. Hajipour and F. Rafiee, Org. Prep. Proced. Int., 2010, 42, 285.
20 R. Sheldon, Chem. Commun., 2001, 2399.
21 R. Hagiwara and Y. Ito, J. Fluorine Chem., 2000, 105, 221.
22 T. Welton, Chem. Rev., 1999, 99, 2071.
23 M. Mamaghani, F. Shirini, M. Sheykhan and M. Mohsenimehr, RSC Adv.,
2015, 5, 44524.
24 L. Kheirkhah, M. Mamaghani, N.O. Mahmoodi, A. Yahyazadeh, A. Fallah
Shojaei and Y. Rostamli, J. Chin. Chem. Soc., 2016, 63, 410.
25 A. Badrian, M. Mamaghani and S. Kamyabi, Phosphorus Sulfur Silicon,
2016, 191, 1375.
Received 10 November 2016; accepted 9 December 2016
Paper 1604421 doi: 10.3184/174751917X14815427219202
Published online: 22 January 2017
References
1
2
3
M. Khafagy, A. El-Wahas, F. Eid and A. El-Agrody, Il Farmaco., 2002,
57, 715.
K. Hiramoto, A. Nasuhara, K. Michiloshi, T. Kato and K. Kikugawa,
Mutat. Res., 1997, 395, 47.
D.R. Anderson, S. Hegde, E. Reinhard, L. Gomez, W.F. Vernier, L. Lee, S.
Liu, A. Sambandam, P.A. Snider and L. Masih, Bioorg. Med. Chem. Lett.,
2005, 15, 1587.
4
C. Dell and C. Smith, European Patent Appl.: EP537949 Chem. Abstr.,
1993, 119, 139102d.
26 M. Mamaghani, R. Hossein Nia, F. Shirini, K. Tabatabaeian and M. Rassa.
Med. Chem. Res., 2015, 24, 1916.
27 M. Mamaghani, Kh. Tabatabaeian, M. Pourshiva and R. Hossein Nia. J.
Chem. Res., 2015, 39, 314.
28 R. Hossein Nia, M. Mamaghani, F. Shirini, Kh. Tabatabaeian and M.
Heidary, Org. Prep. Proc. Int., 2014, 46, 152.
29 R. Ballini, G. Bosica and M.L. Conforti, Tetrahedron, 2001, 57, 1395.
30 A. Zhang, M. Zhang and H. Chen, Synth. Commun., 2007, 37, 231.
31 Q.Y. Zhuang, D.Q. Shi and S.J. Tu, Chin. J. Appl. Chem., 2002, 19, 1018.
32 R. Ballini, F. Bigi, M.L. Conforti, D. De Santis, R. Maggi, G. Oppici and G.
Sartori, Catal. Today, 2000, 60, 305.
5
6
G. Bianchi and A. Tava, Agric. Biol. Chem., 1987, 51, 2001.
S. Mohr, M. Chirigos, F. Fuhrman and J. Pryor, Cancer Res., 1975, 35,
3750.
G. Shanthi, P. T. Perumal, U. Rao and P. K. Sehgal, Indian J. Chem. B,
2009, 48, 1319.
T.S. Jin, J.C. Xiao, S.J. Wang and T.S. Li, Ultrason. Sonochem., 2004, 11,
393.
T.S. Jin, J.S. Zhang, L.B. Liu, A.Q. Wang and T.S. Li, Synth. Commun.,
2006, 36, 2009.
7
8
9
10 D.Q. Shi, S.I. Zhang, Q.Y. Zhuang and X.S. Wang, Chin. J. Org. Chem.,
2003, 23, 877.
11 T.S. Jin, J.C. Xiao, S.J. Wang, T.S. Li and X.R. Song, Synlett., 2003, 13,
33 K. Gong, H. Wang, D. Fang and Z. Liu, Catal. Commun., 2008, 9, 650.
34 F. Kargar Behbahani and S. Maryam, J. Korean Chem. Soc., 2013, 57, 357.
2001.