An efficient and recyclable bifunctional acid-base ionic liquid for synthesis of 1H-indazolo[1,2-b]phthalazinetriones

Article abstract of DOI:10.1007/s11164-014-1736-0

Abstract A bifunctional ionic liquid, 1,4-dimethyl(4-sulfobutyl)piperazinium hydrogen sulfate ([DMSBP][HSO₄], 1), containing both acid and basic sites was prepared. This ionic liquid was used as a homogeneous and reusable catalyst and efficiently promoted synthesis of 1H-indazolo[1,2-b]phthalazinetriones (5a-m) in a one-pot, four-component condensation reaction of phthalic anhydride, hydrazinium hydroxide, dimedone, and aromatic aldehydes under solvent-free conditions at 80 °C. Advantages of the method include short reaction time, high yields, and simple purification.

Full text of DOI:10.1007/s11164-014-1736-0

Res Chem Intermed
DOI 10.1007/s11164-014-1736-0
An efficient and recyclable bifunctional acid–base ionic
liquid for synthesis of 1H-indazolo[1,2-
b]phthalazinetriones
•
Davood Habibi Atefeh Shamsian
Received: 17 March 2014 / Accepted: 3 June 2014
Ó Springer Science+Business Media Dordrecht 2014
Abstract A bifunctional ionic liquid, 1,4-dimethyl(4-sulfobutyl)piperazinium
hydrogen sulfate ([DMSBP][HSO4], 1), containing both acid and basic sites was
prepared. This ionic liquid was used as a homogeneous and reusable catalyst and
efficiently promoted synthesis of 1H-indazolo[1,2-b]phthalazinetriones (5a–m) in a
one-pot, four-component condensation reaction of phthalic anhydride, hydrazinium
hydroxide, dimedone, and aromatic aldehydes under solvent-free conditions at
80 °C. Advantages of the method include short reaction time, high yields, and
simple purification.
Keywords Bifunctional ionic liquid Á Green chemistry Á 1H-Indazolo[1,2-
b]phthalazinetrione Á Solvent-free
Introduction
The design and synthesis of catalysts with synchronic activation of acidic and basic
sites is an emerging field in chemistry. Cooperation of the different active sites has
been used to promote consecutive reactions with high rates and selectivity [1–7].
Modern synthesis emphasizes use of environmentally benign processes in which
use of toxic and hazardous solvents is avoided [8, 9]. These objectives are perfectly
supported by ionic liquids, which are known to promote organic reactions as benign
dual solvent-catalysts with high performance [10, 11]. This is because ionic liquids
have such notable advantages as extremely low volatility, high thermal stability,
adjustable solubility, and versatile structures [12–16]. The term ‘‘task-specific ionic
D. Habibi (&) Á A. Shamsian
Department of Organic Chemistry, Faculty of Chemistry, Bu-Ali Sina University,
PO Box 6517838683, Hamedan, Iran
e-mail: davood.habibi@gmail.com
123

D. Habibi, A. Shamsian
Scheme 1 Synthesis of 1H-indazolo[1,2-b]phthalazinetriones with an ionic liquid as catalyst
liquids’’ has been used to refer to ionic liquids which have particular properties or
reactivities by virtue of their functional groups [17–19].
Ionic liquid catalysts with basic and/or acidic bifunctional groups have frequently
been reported for Knoevenagel reactions [20–24]. To the best of our knowledge,
however, bifunctional ionic liquids have not been widely used in multicomponent
reactions.
Phthalazine derivatives are an important class of heterocyclic compounds which
contain bridgehead hydrazine and have such properties as anticonvulsant activity
[25], a potent vasorelaxant effect [26], and cardiovascular activity [27]. Several
catalysts, for example p-toluenesulfonic acid [28], silica-supported polyphosphoric
acid [29], N-halosulfonamides [30], and ionic liquids [31, 32], have recently been
used for synthesis of these compounds.
In continuation of our study on ionic liquids and their applications [33], we have
developed an efficient method for synthesis of 1H-indazolo[1,2-b]phthalazinetri-
ones (5a–m) by one-pot, four-component condensation reaction of hydrazinium
hydroxide, phthalic anhydride, dimedone, and aromatic aldehydes in the presence of
an acid–base bifunctional reusable catalyst (1) at 80 °C under solvent free
conditions (Scheme 1).
Experimental
General
All chemicals were high-grade quality purchased from Merck and Aldrich and used
without further purification. Melting points were taken in open capillary tubes with
a Buchi 510 melting point apparatus and are uncorrected. NMR spectra were
recorded in DMSO-d6 by use of Bruker 300 and 400-MHz and Jeol 90-MHz
spectrometers. FT-IR spectra were recorded by use of a Perkin–Elmer 781
spectrophotometer. Mass spectra were obtained with Shimadzu GC–MS-QP 1100
EX.
Procedure for synthesis of 1,4-dimethyl(4-sulfobutyl)piperazinium hydrogen sulfate
[DMSBP][HSO4] (1)
1,4-Dimethylpiperazine (4, 10.0 mmol, 1.4 mL) was added to 1,4-butane sultone
(10.0 mmol, 1.0 mL) and stirred under solvent-free conditions at room temperature.
A white solid zwitterion was formed early in the procedure and the reaction mixture
123

Synthesis of 1H-indazolo[1,2-b]phthalazinetriones
was stirred further (10 h) to complete the reaction. The zwitterion was washed with
diethyl ether (3 9 5 mL), isolated by filtration to remove impurities, and dried
under vacuum at 110 °C (yield 95 %). In the next step, sulfuric acid (10 mmol,
0.5 mL) was added dropwise to this zwitterion (10 mmol, 2.5 g) and the mixture
was stirred at 80 °C for 6 h, to convert the solid zwitterion into a liquid. The ionic
liquid obtained was then washed with ether (3 9 5 mL) to remove the non-ionic
residues and dried under vacuum at 110 °C (yield 94 %).
Spectroscopic data for (1): IR (Nujol): mmax = 2950–3540 (br, acidic O–H), 1182
1
(C–N), 1040 and 901 cm-1 (SO3); H NMR (400 MHz, D2O): d (ppm) 1.79–1.87
(m, 2H, CH2), 1.93–2.02 (m, 2H, CH2), 2.38 (s, 3H, NCH3), 2.78–2.94 (m, 4H,
H-piperazinium), 2.99 (t, J = 7.6, 2H, NCH2), 3.13 (s, 3H, NCH3) and 3.44–3.49
(m, 6H, SCH2 and H-piperazinium); 13C NMR (100 MHz, D2O): d (ppm) 19.99,
21.05, 43.70, 47.33, 49.68, 49.85, 53.84, 59.68. MS, m/z (%): 348 (M?), 251 (M?
–
HSO4), 170 (M? – HSO4SO3) 157 (M? – HSO4CH2SO3), 129 (M? – HSO4
(CH2)3 – SO3), 114 (M? – HSO4(CH2)4SO3).
Procedure for synthesis of 1,4-dimethylpiperazine-diium hydrogen sulfate (2)
A solution of 1,4-dimethylpiperazine (4, 4.0 mmol, 0.56 mL) was added dropwise
to sulfuric acid (8.0 mmol, 98 wt%), at 0 °C over a period of 15 min. in three-
necked flask with magnetic stirrer. The reaction mixture was then stirred for 4 h.
The mixture was washed with diethyl ether (3 9 10 mL) to remove any non-ionic
residues and dried under vacuum at 90 °C (m.p: 92 °C, yield 90 %).
Spectroscopic data for (2): IR (KBr): mmax = 3250–3550 (br, acidic OH), 1182 (C–N),
1120 cm-1 (–SO3); 1H NMR (DMSO): d (ppm) 2.8 (s, 6H, 2CH3), 3.34 (s, 8H, 4CH2) and
5.40 (s, 2H, N–H) ppm; 13C NMR (100 MHz, D2O): d (ppm): 41.80 and 49.96.
Procedure for synthesis of 1,4-dimethyl-disulfopiperazine-diium chloride (3)
A solution of 1,4-dimethylpiperazine (4, 4.0 mmol, 0.56 mL) in CH2Cl2 (20 mL)
was added dropwise to a stirred solution of chlorosulfonic acid (8.0 mmol,
0.53 mL) in dry CH2Cl2 (20 mL) over a period of 10 min at 0 °C, then stirred for a
further 4 h. The solvent was evaporated, and the solid residue was washed with
diethyl ether (3 9 10 mL) to remove any non-ionic residues and dried under
vacuum at 90 °C to give a white solid with double acid sites as acid catalyst (mp:
165 °C, yield 95 %).
Spectroscopic data for (3): IR (KBr): mmax = 3150–3552 (br, acidic OH), 1242
(C–N), 1039 and 920 cm-1 (–SO3); 1H NMR (DMSO): d (ppm) 2.48 (s, 6H, 2CH3),
3.13 (s, 8H, 4CH2) and 8.99 (s, 2H, N–H) ppm; 13C NMR (100 MHz, D2O): d
(ppm): 41.68 and 48.96.
General procedure for synthesis of 1H-indazolo[1,2-b]phthalazine-1,6,11(13H)-
trione derivatives (5a–n)
Dimedone (1.0 mmol) and an aromatic aldehyde (1.0 mmol) were added to a
mixture of hydrazinium hydroxide (1.2 mmol), phthalic anhydride (1.0 mmol), and
123

D. Habibi, A. Shamsian
1 (3 mol %, 0.01 g) at 80 °C and stirred under solvent-free conditions. Reaction
was complete within 5–20 min (confirmed by thin-layer chromatography). The
reaction was cooled to room temperature and H2O (5 mL) added. The solid residue
was isolated by filtration. Crude products were purified by recrystallization from
70:30 ethanol–water and characterized by comparison of their physical data with
those of known 1H-indazolo[1,2-b]phthalazine-1,6,11(13H)-triones.
Selected spectral data for indazolophthalazinetrione derivatives
5c: (3,3-dimethyl-13-(3-nitrophenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11
(2H,13H)-trione): IR (KBr): mmax 2973, 1684, 1661, 1625 cm-1; 1H NMR (300 MHz,
CDCl3) 1.23 (6H, s, 2Me), 2.35 (2H, s, CH2C), 3.24–3.47 (2H, AB system,
J = 18.9 Hz, CHaHbCO), 6.53 (1H, s, CHN), 7.53–8.4 (8H, m, ArH); 13C NMR
(300 MHz, CDCl3); 28.5, 28.8, 34.7,38.2, 50.9, 64.0, 117.2, 121.5, 123.7, 127.7, 128.3,
128.5, 128.9, 129.5; MS (ESI) m/z 417 (M ? 1).
5f: (13-(2,4-dichlorophenyl)-3,3-dimethyl-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-
1
1,6,11(2H,13H)-trione: IR (KBr): mmax 2967, 1664, 1627 cm-1; H NMR (300 MHz,
CDCl3) 1.23 (6H, s, Me), 2.33 (2H, s, CH2C), 3.27–3.43 (2H, AB system, J = 19.4 Hz,
CHaHbCO), 6.64 (1H, s, CHN), 7.26–8.4 (7H, m, ArH); 13C NMR (300 MHz, CDCl3);
28.4, 28.7, 34.6, 38.0, 50.8, 63.5, 118.1, 127.6, 127.7, 128.1, 128.6, 129.0, 131.1, 131.7,
133.2, 133.7, 134.6, 135.1, 152.0, 154.3, 156.1, 192.0; MS (ESI) m/z 441 (M ? 1).
5h: 3,3-dimethyl-13-(naphthalen-2-yl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,
11(2H,13H)-trione: IR (KBr): mmax 2956, 1665, 1619 cm-1 1H NMR (300 MHz,
;
CDCl3): 1.22 (6H, s, 2Me), 2.33 (2H, s, CH2C), 3.24–3.50 (2H, AB system, J = 18.6 Hz,
CHaHbCO), 6.62 (1H, s, CHN), 7.45–8.38 (11H, m, ArH); 13C NMR (300 MHz, CDCl3):
28.4, 28.7, 34.6, 38.1, 50.9, 65.1, 118.6, 124.2, 126.2, 126.3, 126.8, 127.6, 127.7, 127.9,
128.2; MS (ESI) m/z 422 (M ? 1).
Results and discussion
The structure of [DMSBP][HSO4] was determined by use of IR, 1H, 13C NMR, and
mass spectroscopy. The IR spectrum of this ionic liquid contained a broad peak at
2950–3540 cm-1 which is ascribed to O–H stretching of the SO3H group. The peak
observed at 1040 cm-1 is ascribed to vibrational modes of the O–SO2 bond. The 1H
NMR spectrum contained two single peaks at 2.29 and 3.04 ppm which correspond
to the two methyl groups. The different chemical shifts of the methyl groups
adequately explains the asymmetric structure of this ionic liquid.
Thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG)
analysis of 1 were also conducted. The results are depicted in Fig. 1, which shows
the high thermal stability of [DMSBP][HSO4], with decomposition at temperatures
above 270 °C.
To determine the optimum conditions for synthesis of 1H-indazolo[1,2-
b]phthalazinetriones we investigated the reaction of 4-chlorobenzaldehyde, dime-
done, phthalic anhydride, and hydrazinium hydroxide as model reaction in the
presence of different catalysts. To investigate the bifunctionality of the catalyst, a
123

Synthesis of 1H-indazolo[1,2-b]phthalazinetriones
Fig. 1 TGA and DTG results for [DMSBP][HSO4]
Scheme 2 Acidic and basic catalysts
series of catalysts with different acidic or basic properties were prepared and the
effect and activity of the acidic and basic groups were investigated (Scheme 2).
The model reaction was performed with different amounts of 1. The optimum
result was obtained with 0.03 mmol catalyst at 80 °C and solvent-free conditions.
Increasing the amount of catalyst or the temperature resulted in no substantial
improvement of the yield (Table 1).
To confirm the presence of acidic and basic groups in 1, another catalyst was
prepared, for comparison, in which the two acidic protons were present on the
nitrogen of the tertiary amine, resulting in an acidic catalyst. This 1,4-
dimethylpiperazine-diium hydrogen sulfate catalyst (2), was synthesized by addition
of 4 to sulfuric acid. The 1H NMR spectrum of 2 contained three peaks at 2.48 (6H,
1
2CH3), 3.13 (8H, 4CH2), and 8.63 (2H, N–H) ppm whereas the H NMR spectrum
of 4 contained two peaks at 1.57 (6H, 2CH3) and 1.72 (8H, 4CH2) ppm. The proton
shifts in the spectrum of 2, compared with the raw material, and the important acidic
123

D. Habibi, A. Shamsian
Table 1 Optimization of the amounts of different catalysts (1–5) under solvent-free conditions at 80 °C
Catalyst
Amount (mmol)
Time (min)
Isolated yield (%)
1st run
2nd run
3rd run
1st run
2nd run
3rd run
1
2
3
4
5
0.03
0.10
0.10
0.50
0.50
0.07
0.20
0.20
0.75
0.75
0.1
5
30
30
30
30
94
50
68
45
42
94
52
73
50
54
95
64
76
55
58
0.50
0.50
1.0
1.0
Bold values indicate the best condition
Reaction conditions: 4-chlorobenzaldehyde (1.0 mmol), dimedone (1.0 mmol), hydrazinium hydroxide
(1.2 mmol), phthalic anhydride (1.0 mmol)
hydrogen peak at 8.63 ppm confirms the formation of 2. When catalyst 2 was used
to perform the model reaction the yield was poor.
These results therefore illustrate that the N-protonated amino group was poorly
active in catalyzing the model reaction and the acidic proton must be in the
proximity of the sulfonate group for catalysis of the reactions. These comparisons
adequately confirm cooperation between Brønsted acidic and Lewis basic sites and
confirm the structure of 1.
We also wished to investigate the position in which the sulfonate group was most
active in promotion of this reaction. Thus, for comparative purposes, we prepared
another acidic catalyst (3). To prepare this catalyst, 4 was added to chlorosulfonic
acid at low temperature. When the base is added dropwise to the acid (ratio 1:2),
there is no excess amount of base which avoids formation of by-products.
Moreover, according to the literature [34, 35], in the reaction of amines with
chlorosulfonic acid at low temperature, the mechanism is nucleophilic substitution
(substitution of the Cl of ClSO3H by the nitrogen of the tertiary amine), not an acid–
base reaction [36]. In addition, peaks of the acidic hydrogen of 3 and ClSO3H were
observed at 8.99 and 13.45 ppm, respectively. The difference between the positions
of the peaks of the acidic hydrogens in 3 and ClSO3H confirmed that the peak
1
observed at 8.99 ppm in the H NMR spectrum of 3 is correctly assigned to the
SO3H group of acidic catalyst 3. The model reaction did not proceed to completion
with acidic catalyst 3, even when the amount of the catalyst was increased
(Table 1). The low activity of catalysts 2 and 3 was presumably because of steric
hindrance of the tertiary amine. To summarize, although the sulfonic acid group
(SO3H) is a highly acidic group suitable for catalysis of the reaction, the position of
the group in the structure of the catalyst is very important. When the SO3H group is
oriented away from the crowded center, it acts as an efficient acidic center for
catalysis of the reaction.
Also, when the model reaction was repeated under similar conditions with the
basic homogeneous analogues 4 and 5, the reactions were sluggish with low yields
of products (Table 1). This means that basic catalysts can not promote this reaction.
Finally, it was found that 1 catalyzes the reaction very efficiently, in a short
reaction time, with high yield. The results indicate that the crucial factor responsible
123

Synthesis of 1H-indazolo[1,2-b]phthalazinetriones
Table 2 Synthesis of indazolophthalazinetrione derivatives (5a–m) catalyzed with 1 at 80 °C under
solvent-free conditions
Entry
R
Product
Time
(min) (%)
Yielda m.p. °C
Found
Reported
[28, 30, 31]
1
2
C6H5
5a
5b
7
5
92
94
205–208 204–206
264–262 264–262
O
O
N
N
O
O
Cl
4-ClC6H4
O
N
N
O
O
3
4
3-O2NC6H4
4-MeC6H4
5c
5
94
85
271–268 272–270
228–226 229–227
NO2
O
N
N
O
O
e
M
5d 10
O
N
N
O
e
Me
O
M
O
5
6
7
3,4,5-(OMe)3C6H4
5e
5f
15
88
93
89
236–234 232–234
219–221 219–221
222–225 223–225
O
M
e
O
O
N
N
O
Cl
2,4-Cl2C6H3
7
O
Cl
O
N
N
O
O
NO2
O
4-O2NC6H4
5g
7
N
N
O
O
8
9
2-naphthyl
1-naphthyl
5h 12
90
87
253–251 251–252
275–278 273–275
O
N
N
O
O
5i
15
O
N
N
O
123

D. Habibi, A. Shamsian
Table 2 continued
Entry
R
Product
Time
(min)
Yielda
(%)
m.p. °C
Found
Reported
[28, 30, 31]
Cl
10
2,3-Cl2C6H3
5j
8
89
88
264–266
266–268
Cl
O
O
O
N
N
e
SM
11
4-MeSC6H4
5k
10
227–230
229–231
O
O
N
N
O
12
13
3-HOC6H4
5l
10
20
85
87
265–268
172–175
268–270
171–173
OH
O
O
N
N
O
C6H4(CH2)2
5m
O
O
N
N
O
14
Octanal
–
5n
24 h
–
–
–
a
Isolated yield
for the efficiency of 1 is, apparently, its cooperative behavior, which results in the
most active catalyst used in this study.
Under these optimized conditions, a variety of substituted aldehydes were used
for preparation of the corresponding 1H-indazolo[1,2-b]phthalazinetriones (5a–
m) in the presence of 1 (Table 2).
Aromatic aldehydes carrying either electron-donating or electron-withdrawing
substituents reacted efficiently giving excellent yields. Benzaldehyde and aromatic
aldehydes bearing electron-withdrawing groups, for example nitro or halogen
(entries 2 and 3) require a shorter reaction times to give higher yields than those
bearing electron-donating groups, for example methoxy or methyl (entries 4 and 5).
All the synthesized compounds are known and were characterized by comparison of
their melting points and spectral data with those of authentic samples.
One major advantage of this procedure is the simple work up and purification of
the product, because the ionic liquid is entirely miscible in water whereas the
products are not. After separation of the products, the catalyst was easily recovered
by removal of the water. The reusability of 1 was investigated in different runs. The
catalyst was recovered from the aqueous medium, dried under vacuum, and reused
in five successive runs without substantial loss of activity (Fig. 2).
A plausible mechanism for synthesis of the indazolophthalazinetriones in the
presence of [DMSBP][HSO4] is shown in Scheme 3. This mechanism is proposed
123

Synthesis of 1H-indazolo[1,2-b]phthalazinetriones
Fig. 2 Reusability of 1 in the model reaction
Scheme 3 Proposed mechanism for synthesis of 1H-indazolo[1,2-b]phthalazineriones with
[DMSBP][HSO4] as catalyst
on the basis of the assumption of acid–base cooperation in the ionic liquid.
According to the mechanism, the first step of this reaction (I) is the interaction
between the basic site of the ionic liquid and dimedone forming intermediate II by
Knoevenagel condensation of dimedone and aromatic aldehyde in the presence of
the catalyst. In the next step, cooperation of the acid and basic sites of this ionic
liquid leads to Michael-type addition of formed phthalhydrazide to intermediate II.
Finally, cyclocondensation and dehydration of these intermediates occur to provide
the corresponding products (III).
123

D. Habibi, A. Shamsian
Table 3 Comparison of 1 with other catalysts for synthesis of indazolophthalazinetriones
Entry Catalyst and conditions
Time
Isolated
TON
TOF
(min-1
)
(min) yield (%) (min-1
)
1
2
3
4
PEG-OSO3H (8 mol %), 80 °C [37]
Cellulose-SO3H (4 mol %), solvent-free, 80 °C [38]
1 (3 mol %), solvent-free, 80 °C [present work]
H2SO4, [bmim]BF4 (15 mol %),
H2O–EtOH, reflux [31]a
10
6
92
88
94
88
11.5
22
1.15
3.6
5
31.3
6
6.3
25
0.23
5
6
Silica–sulfuric acid (6.5 mol %),
solvent-free, 100 °C [39]a
HPA (3 mol %), solvent-free, 100 °C [32]a
7
8
91
92
14
2
4
30.6
Bold values indicate the best condition
a
Based on reaction of 4-chlorobenzaldehyde, dimedone, and phthalhydrazide
In addition, to compare the capability and efficiency of 1 with those of previous
methods, results from use of different catalysts for synthesis of 1H-indazolo[1,2-
b]phthalazinetriones by the model reaction were studied. The values of the turnover
number (TON) and turnover frequency (TOF) confirm that 1 is a suitable catalyst
with regard to reaction times and product yield (Table 3).
Conclusion
In summary, we report the synthesis of a new reusable acid–base bifunctional ionic
liquid catalyst (1). This homogeneous catalyst is a good solvent for promotion of
one-pot multicomponent condensation of phthalic anhydride, hydrazinium hydrox-
ide, dimedone, and aromatic aldehydes.
The main advantage of the method is easy product isolation, because the catalyst
is immiscible with most organic solvents and can be separated by extraction with
water. Other advantages of the method include high efficiency, low cost, short
reaction times, and clean reaction with fewer side-products. Finally, it conforms
with the principles of green chemistry.
Acknowledgments We are grateful to Bu-Ali Sina University, Hamedan 6517838683, Iran, for support
of this work.
References
´
1. A. Corma, M. Boronat, M.J. Climent, S. Iborra, R. Monton, M.J. Sabater, Phys. Chem. Chem. Phys.
13, 17255 (2011)
2. A.K. Chakraborti, S.R. Roy, J. Am. Chem. Soc. 131, 6902 (2009)
3. S.R. Roy, A.K. Chakraborti, Org. Lett. 12, 3866 (2010)
´
4. E. Garrido-Ramırez, B. Theng, M. Mora, Appl. Clay Sci. 47, 182 (2010)
5. L. Zhang, X. Fu, G. Gao, Chem. Cat. Chem. 3, 1359 (2011)
6. L. Zhang, Y. Yang, Y. Xue, X. Fu, Y. An, G. Gao, Catal. Today 158, 279 (2010)
7. R.K. Zeidan, S.J. Hwang, M.E. Davis, Angew. Chem. Int. Ed. 45, 6332 (2006)
123

Synthesis of 1H-indazolo[1,2-b]phthalazinetriones
8. S. Banerjee, A. Horn, H. Khatri, G. Sereda, Tetrahedron Lett. 52, 1878 (2011)
9. S. Banerjee, G. Sereda, Tetrahedron Lett. 50, 6959 (2009)
10. M.H. Valkenberg, C. de Castro, W.F. Hoelderich, Green Chem. 4, 88 (2002)
11. T. Welton, Coord. Chem. Rev. 248, 2459 (2004)
12. K. Gong, D. Fang, H.-L. Wang, X.-L. Zhou, Z.-L. Liu, Dyes Pigm. 80, 30 (2009)
13. A.C. Cole, J.L. Jensen, I. Ntai, K.L.T. Tran, K.J. Weaver, D.C. Forbes, J.H. Davis, J. Am. Chem. Soc.
124, 5962 (2002)
14. J. Gui, H. Ban, X. Cong, X. Zhang, Z. Hu, Z. Sun, J. Mol. Catal. A Chem. 225, 27 (2005)
15. J. Gui, X. Cong, D. Liu, X. Zhang, Z. Hu, Z. Sun, Catal. Commun. 5, 473 (2004)
16. P. Wasserscheid, M. Sesing, W. Korth, Green Chem. 4, 134 (2002)
17. K. Motokura, M. Tada, Y. Iwasawa, Chem. Asian J. 3, 1230 (2008)
¨
18. H. Groger, J. Wilken, Angew. Chem. Int. Ed. 40, 529 (2001)
19. Y. Shen, X. Feng, Y. Li, G. Zhang, Y. Jiang, Tetrahedron 59, 5667 (2003)
20. M. Zhang, P. Zhao, Y. Leng, G. Chen, J. Wang, J. Huang, Chem. Eur. J. 18, 12773 (2012)
21. M.J. Climent, A. Corma, S. Iborra, A. Velty, J. Mol. Catal. A Chem. 182, 327 (2002)
22. G. Postole, B. Chowdhury, B. Karmakar, K. Pinki, J. Banerji, A. Auroux, J. Catal. 269, 110 (2010)
23. C. Yue, A. Mao, Y. Wei, M. Lu¨, Catal. Commun. 9, 1571 (2008)
24. J.R. Harjani, S.J. Nara, M.M. Salunkhe, Tetrahedron Lett. 43, 1127 (2002)
`
25. S. Grasso, G. De Sarro, A. De Sarro, N. Micale, M. Zappala, G. Puja, M. Baraldi, C. De Micheli, J.
Med. Chem. 43, 2851 (2000)
26. N. Watanabe, Y. Kabasawa, Y. Takase, M. Matsukura, K. Miyazaki, H. Ishihara, K. Kodama, H.
Adachi, J. Med. Chem. 41, 3367 (1998)
27. Y. Nomoto, H. Obase, H. Takai, T. Hirata, M. Teranishi, J. Nakamura, K. Kubo, Chem. Pharm. Bull.
38, 1591 (1990)
28. M. Sayyafi, M. Seyyedhamzeh, H.R. Khavasi, A. Bazgir, Tetrahedron 64, 2375 (2008)
29. H.R. Shaterian, A. Hosseinian, M. Ghashang, Arkivoc ii, 59–67 (2009)
30. R. Ghorbani-Vaghei, R. Karimi-Nami, Z. Toghraei-Semiromi, M. Amiri, M. Ghavidel, Tetrahedron
67, 1930 (2011)
31. J.M. Khurana, D. Magoo, Tetrahedron Lett. 50, 7300 (2009)
32. R. Fazaeli, H. Aliyan, N. Fazaeli, Open Catal. J. 3, 14–18 (2010)
33. D. Habibi, A. Shamsian, J. Chem. Res. 37, 253 (2013)
34. Ajinomoto Co Inc, Chem. Abs. 101, 210548 (1984)
35. N. Sakota, S. Nomura, S. Ito, Chem. Abs. 114, 22873 (1991)
36. A. Zare, A.R. Moosavi-Zare, M. Merajoddin, M.A. Zolfigol, T. Hekmat-Zadeh, A. Hasaninejad, A.
Khazaei, M. Mokhlesi, V. Khakyzadeh, F. Derakhshan-Panah, J. Mol. Liq. 167, 69 (2012)
37. A. Hasaninejed, M.R. Kazerooni, A. Zare, Catal. Today 196, 148 (2012)
38. H.R. Shaterian, F. Rigi, Res. Chem. Intermed. 39, 1 (2013)
39. H.R. Shaterian, M. Ghashang, M. Feyzi, Appl. Catal. A Gen. 345, 128 (2008)
123