Convenient synthesis of polysubstituted pyrroles and symmetrical and unsymmetrical bis-pyrroles catalyzed by H3PW12O40

Article abstract of DOI:10.1016/j.crci.2015.11.006

A mild and environmentally-benign protocol for the efficient synthesis of polysubstituted pyrroles via a one-pot three-component reaction of amines, α-bromo ketones and dialkyl acetylenedicarboxylate using H₃PW₁₂O₄₀ as a recyclable heterogeneous catalyst under solvent-free conditions at room temperature is reported. Importantly, the synthesis of symmetrical and unsymmetrical polysubstituted bis-pyrroles has been performed in good yields for the first time, which can be considered as a salient feature of this protocol.

Full text of DOI:10.1016/j.crci.2015.11.006

C. R. Chimie xxx (2016) 1e9
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Full paper/Memoire
Convenient synthesis of polysubstituted pyrroles and
symmetrical and unsymmetrical bis-pyrroles catalyzed by
H3PW12O40
Mohammad Soltani, Iraj Mohammadpoor-Baltork*, Ahmad R. Khosropour*,
Majid Moghadam, Shahram Tangestaninejad, Valiollah Mirkhani
Department of Chemistry, Catalysis Division, University of Isfahan, Isfahan 81746-73441, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
A mild and environmentally-benign protocol for the efficient synthesis of polysubstituted
Received 25 July 2015
Accepted 2 November 2015
Available online xxxx
pyrroles via a one-pot three-component reaction of amines, a-bromo ketones and dialkyl
acetylenedicarboxylate using H3PW12O40 as a recyclable heterogeneous catalyst under
solvent-free conditions at room temperature is reported. Importantly, the synthesis of
symmetrical and unsymmetrical polysubstituted bis-pyrroles has been performed in good
yields for the first time, which can be considered as a salient feature of this protocol.
Keywords:
Polysubstituted pyrroles
Heteropoly acids
Bis-pyrroles
ꢀ
© 2015 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Amines
Solvent-free
1. Introduction
products [8], biologically active compounds [9], and drugs
[10]. Various pyrrole derivatives have been shown to
During the recent years multi-component reactions
(MCRs) have received great attention due to their wide
range of applications in pharmaceutical chemistry for the
construction of diversified structural scaffolds [1], synthe-
sis of natural products [2], and combinatorial chemistry [3].
Compared to the classical stepwise reactions, MCRs offer
significant benefits such as high atom economy, straight-
forward experimental procedures, high overall chemical
yields, short reaction times and avoidance of costly and
energy consuming intermediate separation and purifica-
tion steps which minimize waste generation, making the
chemical transformations environmentally-benign [4e7].
Pyrrole and its derivatives have attracted considerable
attention because of their presence in a variety of natural
possess interesting biological properties such as antibac-
terial [11], antiviral [12], anti-inflammatory [13], antifungal
[14], antioxidant [15] and anticancer [16] activities.
Furthermore, these compounds are widely used in mate-
rials science [17], as organic conducting materials [18] and
as key intermediates for the synthesis of polymers [19],
porphyrins [20], dyes [21a], and functionalized materials
[22]. Due to their importance and widespread applications,
several synthetic routes such as Hantzsch [23], Knorr
[16,24], Paal-Knorr [25], and ClausoneKaas [26] reactions,
transition metal-catalyzed cyclizations [27], and multi-
component reactions [28] have been reported for the syn-
thesis of pyrroles. However, many of the reported methods
suffer from one or more drawbacks including unsatisfac-
tory yields, long reaction times, the use of toxic organic
solvents, expensive and moisture sensitive catalysts, and
cumbersome experimental procedures. Thus, the devel-
opment of an alternative method for the synthesis of
* Corresponding authors.
E-mail addresses: imbaltork@sci.ui.ac.ir (I. Mohammadpoor-Baltork),
khosropour@chem.ui.ac.ir (A.R. Khosropour).
http://dx.doi.org/10.1016/j.crci.2015.11.006
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1631-0748/© 2015 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Please cite this article in press as: M. Soltani, et al., Convenient synthesis of polysubstituted pyrroles and symmetrical and
unsymmetrical bis-pyrroles catalyzed by H3PW12O40
,
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j.crci.2015.11.006

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M. Soltani et al. / C. R. Chimie xxx (2016) 1e9
pyrroles by using a readily available, environmentally
friendly and cheap catalyst under mild conditions is still
highly desired.
0.05 mol% of the catalyst (Table 1, entry 9). It was noted that
increasing the amount of the catalyst from 0.05 mol% to
0.07 mol% did not alter either the reaction time or the yield
of the desired product.
In order to expand the generality of the present method,
the synthesis of a wide range of pyrroles was examined
under the optimized conditions and the results are sum-
marized in Table 2. A variety of aromatic amines were
The application of Keggin-type heteropoly acids as
environmentally friendly and green homogeneous or het-
erogeneous catalysts has been recognized and established
because of their non-corrosive nature, low cost, safety, low
quantity of waste, stability, low toxicity, recoverability, and
reusability. Heteropoly acids, especially H3PW12O40, have
gained importance owing to their stronger acidity, higher
thermal stability and selectivity properties. Therefore, a
wide variety of synthetically valuable organic trans-
formations using these solid acid catalysts have been re-
ported in the literature [29].
As a part of our ongoing efforts on the development of
environmentally-benign synthetic transformations using
heteropoly compounds [30], herein we would like to report
a convenient one-pot multi-component method for the
synthesis of polysubstituted pyrroles, symmetrical and
reacted smoothly with various a-bromo ketones and dia-
lkyl acetylenedicarboxylate in the presence of H3PW12O40
at room temperature to afford the desired polysubstituted
pyrroles in excellent yields (Table 2, entries 1e10). Aliphatic
amines such as benzyl amine and methyl amine were also
reacted efficiently to give the corresponding poly-
substituted pyrroles in high yields (Table 2, entries 11, 12).
Encouraged by the excellent results obtained for poly-
substituted pyrroles, the potential of this catalytic protocol
was further explored for the synthesis of bis-pyrroles and
the results are given in Table 3. The reaction of diamines
such as 1,4-phenylenediamine and 1,3-phenylenediamine
unsymmetrical bis-pyrroles using H3PW12O40 as
a
commercially available catalyst under solvent-free condi-
tions at room temperature (Scheme 1).
with a-bromo ketones and dimethyl acetylenedicarbox-
ylate proceeded in the presence of catalytic amounts of
H3PW12O40 and gave the corresponding symmetrical and
unsymmetrical polysubstituted bis-pyrroles in moderate to
good yields. To the best of our knowledge, no examples of
the synthesis of polysubstituted bis-pyrroles via the multi-
2. Results and discussion
Initially, we attempted the threeecomponent reaction
component reaction of diamines,
a-bromo ketones and
between aniline (1 mmol),
a-bromo acetophenone
dimethyl acetylenedicarboxylate have been reported and
consequently, such a synthesis can be considered as a
remarkable characteristic of the present protocol in the
preparation of these important heterocyclic compounds.
A probable mechanistic pathway for the synthesis of
polysubstituted pyrroles is illustrated in Scheme 2. First,
H3PW12O40 activates dialkyl acetylenedicarboxylate to give
A. Then, Michael-type addition of amine 1 with A provides
(1 mmol) and dimethyl acetylenedicarboxylate (1 mmol) in
the absence of the catalyst under solvent-free conditions at
room temperature. No reaction was observed even after
10 h (Table 1, entry 1). Then, the reaction was performed in
the presence of various Lewis acids such as ZnCl2, MgCl2,
MnCl2, BiCl3, Bi(OTf)3 and heteropoly acids such as
H3PMo12O40, H4SiW12O40 and H3PW12O40 (Table 1, entries
1e9). Of these, H3PW12O40 was found to be the most
effective catalyst to carry out this reaction. Finally, the same
reaction was carried out using various amounts of
H3PW12O40 (0.03, 0.05 and 0.07 mol%) (Table 1, entries
9e11); the best yield of the product was obtained using
the
a
,
b
-unsaturated N-arylamine intermediate B which
-bromo ketone 2 produces the inter-
upon reaction with
a
mediate C. Intramolecular cyclization of C, followed by
dehydration in the presence of the catalyst generates the
Scheme 1. Synthesis of polysubstituted pyrroles and bis-pyrroles catalyzed by H3PW12O40
.
Please cite this article in press as: M. Soltani, et al., Convenient synthesis of polysubstituted pyrroles and symmetrical and
unsymmetrical bis-pyrroles catalyzed by H3PW12O40
j.crci.2015.11.006
,
Comptes Rendus Chimie (2016), http://dx.doi.org/10.1016/

M. Soltani et al. / C. R. Chimie xxx (2016) 1e9
3
Table 1
Optimization of reaction conditions for the synthesis of polysubstituted pyrroles.a
Entry
Catalyst (mmol)
Yield (%)b
1
No catalyst
e
2
3
4
5
6
7
8
9
ZnCl2 (0.05)
MgCl2 (0.05)
MnCl2 (0.05)
BiCl3 (0.05)
Bi(OTf)3 (0.05)
H3PMo12O40 (0.05)
H4SiW12O40 (0.05)
H3PW12O40 (0.05)
H3PW12O40 (0.03)
H3PW12O40 (0.07)
40
22
20
40
47
40
63
94
60
94
10
11
a
Reaction conditions: aniline (1 mmol), a-bromo acetophenone (1 mmol), dimethyl acetylenedicarboxylate (1 mmol), catalyst (0.05 mmol), at rt for 1 h.
Isolated yield.
b
target heterocyclic compound 4 and liberates the catalyst
for the next run.
spectra were recorded in a CDCl3 solution on a Bruker-
Avance 400 spectrometer. Elemental analysis was done
on a LECO, CHNS-932 analyzer.
The recyclability and reusability of the H3PW12O40
catalyst were scrutinized in the model reaction under the
optimized conditions and the results are shown in Table 4.
When the reaction was completed, ethyl acetate (10 mL)
was added and the catalyst was easily separated by simple
filtration. The recovered catalyst was washed with ethyl
acetate, dried and reused in another set of reaction. It was
observed that the catalyst can be recycled and reused up to
four runs without any significant loss in its efficacy and
activity.
4.2. General procedure for the synthesis of polysubstituted
pyrroles
To a mixture of amine 1 (1 mmol), a-bromo ketone 2
(1 mmol) and dialkyl acetylenedicarboxylate 3 (1 mmol),
was added H3PW12O40 (0.05 mmol, 144 mg). The reaction
mixture was stirred at room temperature for 1 h. The
progress of the reaction was monitored by TLC (eluent:
ethyl acetate/petroleum ether, 1:7). After completion of the
reaction, ethyl acetate (10 mL) was added; the catalyst was
separated by simple filtration and washed with ethyl ace-
tate (10 mL). Evaporation of the solvent followed by puri-
fication of the crude product by column chromatography
on silica gel (eluent: ethyl acetate/petroleum ether, 1:7)
afforded the pure product (Table 2).
3. Conclusion
In conclusion, an efficient and mild protocol has been
developed for the synthesis of polysubstituted pyrroles
using H3PW12O40 as a commercially available, inexpensive,
environmentally friendly, non-corrosive, and reusable
catalyst under solvent-free and ambient reaction condi-
tions. We have also devised the first example of
a
straightforward synthesis of symmetrical and unsymmet-
rical polysubstituted bis-pyrroles via a one-pot multi-
4.3. General procedure for the synthesis of polysubstituted
bis-pyrroles
component reaction of diamines,
a-bromo ketones and
dimethyl acetylenedicarboxylate which makes this process
attractive for the synthesis of these important heterocyclic
compounds.
A mixture of diamine 5 (1 mmol),
a-bromo ketone 2
(2 mmol), dimethyl acetylenedicarboxylate 3 (2 mmol) and
H3PW12O40 (0.1 mmol, 288 mg) was stirred at room tem-
perature 1.5 h (for unsymmetrical bis-pyrroles, the reaction
4. Experimental
was performed with 1 mmol
a-bromo ketone 2 and 1 mmol
a
-bromo ketone 6). The progress of the reaction was
4.1. General
monitored by TLC (eluent: ethyl acetate/petroleum ether,
1:5). The work-up was performed as described in the
general procedure for the synthesis of polysubstituted
pyrroles and the crude product was purified by column
chromatography on silica gel (eluent: ethyl acetate/petro-
leum ether, 1:5) to give the pure product (Table 3).
Melting points were determined using a Stuart Scien-
tific SMP2 apparatus. FT-IR spectra were recorded on a
Nicolet-Impact 400D instrument in the range of
400e4000 cmꢀ1 1H and 13C NMR (400 and 100 MHz)
.
Please cite this article in press as: M. Soltani, et al., Convenient synthesis of polysubstituted pyrroles and symmetrical and
unsymmetrical bis-pyrroles catalyzed by H3PW12O40
,
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j.crci.2015.11.006

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M. Soltani et al. / C. R. Chimie xxx (2016) 1e9
Table 2
a
Synthesis of polysubstituted pyrroles catalyzed by H3PW12O40
.
Entry
Amine
α-Bromo ketone
Product
Yield (%)
94
1
2
3
90
91
4
5
90
93
6
7
95
95
8
9
94
92
90
10
11
89
85
12
aReaction conditions: amine 1 (1 mmol),
conditions at rt for 1 h.
a-bromo ketone 2 (1 mmol), dialkyl acetylenedicarboxylate 3 (1 mmol), H3PW12O40 (5 mol%), under solvent-free
bIsolated yield.
Please cite this article in press as: M. Soltani, et al., Convenient synthesis of polysubstituted pyrroles and symmetrical and
unsymmetrical bis-pyrroles catalyzed by H3PW12O40
j.crci.2015.11.006
,
Comptes Rendus Chimie (2016), http://dx.doi.org/10.1016/

Table 3
Synthesis of polysubstituted bis-pyrroles catalyzed by H3PW12O40
.
Entry Diamine 5
α-Bromo ketone 2
α-Bromo ketone 6 Bis-pyrrole 7
Yield (%)a
-
1b
77
-
-
2 b
3 b
4c
75
75
70
5c
65
-
6b
45
-
7 b
40
aIsolated yield.
bReaction conditions: diamine 5 (1 mmol),
a-bromo ketone 2 (2 mmol), and dimethyl acetylenedicarboxylate 3 (2 mmol), H3PW12O40 (10 mol%), under
solvent-free conditions at rt for 1.5 h.
cReaction conditions: diamine 5 (1 mmol),
a
-bromo ketone 2 (1 mmol),
a-bromo ketone 6 (1 mmol), dimethyl acetylenedicarboxylate 3 (2 mmol),
H3PW12O40 (10 mol%), under solvent-free conditions at rt for 1.5 h.
Please cite this article in press as: M. Soltani, et al., Convenient synthesis of polysubstituted pyrroles and symmetrical and
unsymmetrical bis-pyrroles catalyzed by H3PW12O40
,
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j.crci.2015.11.006

6
M. Soltani et al. / C. R. Chimie xxx (2016) 1e9
Scheme 2. Probable mechanistic pathway for the synthesis of polysubstituted pyrroles.
5. Spectroscopic data of the products
8.00 (d, J ¼ 8.4 Hz, 2H). 13C NMR (100 MHz, CDCl3):
d 51.4,
53.2, 118.6, 120.7, 123.0, 124.2, 125.4, 128.6, 129.2, 131.4,
131.7, 140.6, 160.1, 166.1.
5.1. Dimethyl 1,5-diphenyl-1H-pyrrole-2,3-dicarboxylate
(Table 2, entry 1)
5.4. Dimethyl 5-(4-fluorophenyl)-1-phenyl-1H-pyrrole-2,3-
dicarboxylate (Table 2, entry 4)
Yellow oil [28c]. IR (KBr): nmax ¼ 2931, 1725, 1501, 1452,
1345, 1257, 1085, 1015, 835, 805, 751 cmꢀ1 1H NMR
.
(400 MHz, CDCl3):
J ¼ 8.0 Hz, 4H), 7.02 (t, J ¼ 7.6 Hz, 2H), 7.20 (t, J ¼ 8.4 Hz, 4H).
13C NMR (100 MHz, CDCl3):
51.2, 52.8, 118.6, 120.7, 122.3,
124.2, 125.4, 128.8, 129.2, 130.9, 131.9, 132.1, 140.3, 160.9,
166.3.
d 3.62 (s, 3H), 3.66 (s, 3H), 6.82 (d,
Yellow oil. IR (KBr): nmax ¼ 2933, 1721, 1505, 1452, 1355,
1261, 1085, 1021, 835, 749 cmꢀ1. 1H NMR (400 MHz, CDCl3):
d
d
3.74 (s, 3H), 3.79 (s, 3H), 6.93 (s, 1H), 7.02 (t, J ¼ 7.2 Hz,
2H), 7.35e7.47 (m, 7H). 13C NMR (100 MHz, CDCl3):
d
51.2,
52.8, 118.6, 120.7, 125.0, 126.6, 127.3, 127.8, 128.6, 129.2,
131.3, 132.4, 139.2, 140.8, 160.9, 167.3.
5.2. Dimethyl 5-(4-bromophenyl)-1-phenyl-1H-pyrrole-2,3-
dicarboxylate (Table 2, entry 2)
5.5. Dimethyl 5-(naphthalen-1-yl)-1-phenyl-1H-pyrrole-2,3-
dicarboxylate (Table 2, entry 5)
Yellow oil [28d]. IR (KBr): nmax ¼ 2927, 1723, 1498, 1450,
1351, 1257, 1080, 1017, 835, 755 cmꢀ1 1H NMR (400 MHz,
.
Brown oil. IR (KBr): nmax ¼ 2931, 1731, 1497, 1451, 1355,
1295, 1077, 1005, 829, 797, 753 cmꢀ1 1H NMR (400 MHz,
.
CDCl3):
d 3.59 (s, 3H), 3.65 (s, 3H), 7.07 (s, 1H), 7.13 (d,
J ¼ 7.2 Hz, 2H), 7.21 (t, J ¼ 7.6 Hz, 1H), 7.37 (t, J ¼ 8.3 Hz, 2H),
CDCl3):
d 3.62 (s, 3H), 3.67 (s, 3H), 6.95e6.98 (m, 1H),
7.59 (d, J ¼ 8.4 Hz, 2H), 7.99 (d, J ¼ 8.4 Hz, 2H). 13C NMR
7.04e7.09 (m, 2H), 7.10e7.19 (m, 2H), 7.20e7.25 (m, 2H),
7.35e7.39 (m, 1H), 7.41e7.48 (m, 1H), 7.57e7.64 (m, 2H),
(100 MHz, CDCl3):
d 51.3, 52.8, 120.7, 122.3, 124.3, 125.5,
7.74 (dd, J ¼ 8.3, J ¼ 2.4 Hz, 1H), 7.80 (d, J ¼ 8.2 Hz, 1H). 13
C
128.8, 129.2, 130.9, 132.2, 133.0, 140.3, 160.5, 166.6.
NMR (100 MHz, CDCl3):
d 52.4, 52.8, 112.7, 120.8, 120.9,
123.4, 124.4, 125.9, 126.0, 127.9, 128.4, 128.6, 128.9, 129.9,
130.8, 133.1, 141.7, 161.0, 165.0.
5.3. Dimethyl 5-(4-chlorophenyl)-1-phenyl-1H-pyrrole-2,3-
dicarboxylate (Table 2, entry 3)
5.6. Dimethyl 5-phenyl-1-p-tolyl-1H-pyrrole-2,3-
dicarboxylate (Table 2, entry 6)
Yellow oil. IR (KBr): nmax ¼ 2927, 1728, 1498, 1450, 1353,
1259, 1080, 1018, 835, 754 cmꢀ1. 1H NMR (400 MHz, CDCl3):
d
3.59 (s, 3H), 3.66 (s, 3H), 7.15 (s, 1H), 7.57e7.67 (m, 7H),
Yellow oil [28e]. IR (KBr): nmax ¼ 2924, 1727, 1498, 1447,
1347, 1297, 1255, 1073, 1005, 828, 795, 749 cmꢀ1. 1H NMR
Table 4
(400 MHz, CDCl3):
d 2.42 (s, 3H), 3.62 (s, 3H), 3.66 (s, 3H),
Recycling and reusability of the H3PW12O40 catalyst.a
7.10 (s, 1H), 7.18e7.23 (m, 7H), 7.65 (d, J ¼ 8.1 Hz, 2H). 13
C
Run
Cycle
Yield (%)b
NMR (100 MHz, CDCl3): d 22.7, 51.2, 52.8, 118.6, 120.1, 120.7,
124.3, 125.5, 128.1, 129.2, 130.9, 131.3, 133.0, 140.3, 160.2,
166.5.
1
2
3
4
5
0
1
2
3
4
94
92
90
89
87
5.7. Dimethyl 5-(4-methoxyphenyl)-1-phenyl-1H-pyrrole-
2,3-dicarboxylate (Table 2, entry 7)
a
Reaction conditions: aniline (1 mmol),
a
-bromo acetophenone
(1 mmol), dimethyl acetylenedicarboxylate (1 mmol), H3PW12O40
(5 mmol%), at rt for 1 h.
Yellow oil [28e]. IR (KBr): nmax ¼ 2930, 1728, 1588, 1501,
1359, 1248, 1091, 829, 805, 755 cmꢀ1 1H NMR (400 MHz,
.
b
Isolated yield.
Please cite this article in press as: M. Soltani, et al., Convenient synthesis of polysubstituted pyrroles and symmetrical and
unsymmetrical bis-pyrroles catalyzed by H3PW12O40
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Comptes Rendus Chimie (2016), http://dx.doi.org/10.1016/

M. Soltani et al. / C. R. Chimie xxx (2016) 1e9
7
CDCl3):
d
3.48 (s, 3H), 3.62 (s, 3H), 3.67 (s, 3H), 6.82 (d,
54.1, 118.5, 120.9, 122.3, 124.6, 125.6, 129.3, 134.6, 142.0,
160.1, 166.0.
J ¼ 7.8 Hz, 2H), 7.03 (s, 1H) 7.41 (td, J ¼ 7.8, 1.2 Hz, 2H), 7.49
(td, J ¼ 7.8, 1.2 Hz, 2H), 7.59e7.52 (m, 3H). 13C NMR
(100 MHz, CDCl3):
d
51.2, 52.7, 59.4, 116.7, 120.7, 122.3,
5.13. Tetramethyl 1,10-(1,4-phenylene)bis(5-phenyl-1H-
124.3, 125.4, 129.2, 130.9, 133.0, 140.3, 159.0, 162.1, 166.0.
pyrrole-2,3-dicarboxylate) (Table 3, entry 1)
5.8. Dimethyl 5-(4-bromophenyl)-1-p-tolyl-1H-pyrrole-2,3-
dicarboxylate (Table 2, entry 8)
Mp 105e108 ꢁC. IR (KBr): nmax ¼ 2933, 1731, 1512,
1352,1261, 1105, 841, 805, 751 cmꢀ1 1H NMR (400 MHz,
.
CDCl3):
d 3.69 (s, 6H), 3.78 (s, 6H), 7.12 (s, 2H), 7.33 (t,
Yellow oil [28c]. IR (KBr): nmax ¼ 2938, 1726, 1585, 1503,
J ¼ 7.9 Hz, 2H), 7.38 (t, J ¼ 7.7 Hz, 4H), 7.57 (s, 4H), 7.67 (d,
1366, 1251, 1095, 832, 805, 761 cmꢀ1
.
1H NMR (400 MHz,
J ¼ 7.5 Hz, 4H). 13C NMR (100 MHz, CDCl3):
d 51.8, 54.2,
CDCl3):
d
2.45 (s, 3H), 3.62 (s, 3H), 3.67 (s, 3H), 7.23 (d,
119.2, 121.0, 122.3, 127.7, 129.4, 130.7, 131.9, 138.0, 139.9,
140.2, 161.0, 167.0. Anal. Calcd. for C34H28N2O8: C, 68.91; H,
4.76; N, 4.73. Found: C, 68.80; H, 4.80; N, 4.81.
J ¼ 7.8 Hz, 2H), 7.27 (s, 1H) 7.30 (d, J ¼ 7.3 Hz, 2H), 7.44 (d,
J ¼ 8.9 Hz, 2H), 7.53 (d, J ¼ 8.5 Hz, 2H). 13C NMR (100 MHz,
CDCl3):
d 22.7, 51.2, 52.8, 110.5, 118.6, 120.7, 124.3, 125.5,
128.1, 129.2, 130.2, 130.9, 131.3, 133.0, 140.3, 160.4, 166.4.
5.14. Tetramethyl 1,10-(1,4-phenylene)bis(5-(4-bromophenyl)-
1H-pyrrole-2,3-dicarboxylate) (Table 3, entry 2)
5.9. Diethyl 1,5-diphenyl-1H-pyrrole-2,3-dicarboxylate
(Table 2, entry 9)
Mp 103e105 ꢁC. IR (KBr): nmax ¼ 2927, 1729, 1510, 1448,
1351, 1261, 1085, 1012, 841, 805, 755 cmꢀ1 1H NMR
.
Yellow oil [28g]. IR (KBr): nmax ¼ 2935, 1728, 1595, 1498,
(400 MHz, CDCl3):
7.54e7.60 (m, 4H), 7.76 (d, J ¼ 8.6 Hz, 3H), 7.92 (d, J ¼ 8.6 Hz,
2H). 13C NMR (100 MHz, CDCl3):
51.2, 52.8, 118.4, 120.8,
122.34, 124.2, 125.5, 129.3, 130.9, 132.2, 140.3, 143.5, 160.9,
166.1. Anal. Calcd. for C34H26Br2N2O8: C, 54.42; H, 3.49; N,
3.73. Found: C, 54.53; H, 3.52; N, 3.65.
d 3.76 (s, 6H), 3.83 (s, 6H), 7.44 (s, 4H),
1353, 1251, 1085, 835, 803, 755 cmꢀ1 1H NMR (400 MHz,
.
CDCl3):
d
1.18 (t, J ¼ 6.9 Hz, 3H), 1.37 (t, J ¼ 7.1 Hz, 3H), 3.92
d
(q, J ¼ 6.8 Hz, 2H), 4.16 (q, J ¼ 6.7 Hz, 2H), 6.82 (d, J ¼ 8.0 Hz,
4H), 7.02 (t, J ¼ 7.6 Hz, 2H), 7.21 (t, J ¼ 8.4 Hz, 4H). 13C NMR
(100 MHz, CDCl3): d 13.6, 14.2, 60.0, 62.4, 118.6, 120.7, 125.8,
122.6, 124.3, 125.8, 126.2, 127.1, 128.3, 129.2, 133.0, 140.3,
160.6, 166.4.
5.15. Tetramethyl-1,10-(1,4-phenylene)bis(5-(4-
chlorophenyl)-1H-pyrrole-2,3-dicarboxylate) (Table 3, entry
5.10. Diethyl 5-(4-bromophenyl)-1-phenyl-1H-pyrrole-2,3-
3)
dicarboxylate (Table 2, entry 10)
Mp 98e101 ꢁC. IR (KBr): nmax ¼ 2927, 1729, 1510, 1448,
Brown oil [28f]. IR (KBr): nmax ¼ 2943, 1738, 1578, 1521,
1351, 1261, 1085, 1012, 841, 805, 755 cmꢀ1 1H NMR
.
1364, 1266, 1085, 835, 803, 755 cmꢀ1. 1H NMR (400 MHz,
(400 MHz, CDCl3):
7.54e7.60 (m, 4H), 7.75 (d, J ¼ 8.3 Hz, 4H), 7.92 (d, J ¼ 8.7 Hz,
4H). 13C NMR (100 MHz, CDCl3):
51.2, 52.8, 118.6, 120.7,
d 3.59 (s, 6H), 3.74 (s, 6H), 6.92 (s, 2H),
CDCl3):
d
1.11 (t, J ¼ 6.9 Hz, 3H), 1.26 (t, J ¼ 7.1 Hz, 3H), 3.92
(q, J ¼ 7.1 Hz, 2H), 4.02 (q, J ¼ 6.7 Hz, 2H), 7.44e7.49 (m, 3H),
d
7.55e7.58 (m, 2H) 7.63 (d, J ¼ 8.4 Hz, 2H), 7.74 (d, J ¼ 8.2 Hz,
124.3, 125.65, 128.0, 129.2, 130.9, 133.0, 140.3, 143.78, 160.9,
165.8. Anal. Calcd. for C34H26Cl2N2O8: C, 61.73; H, 3.96; N,
4.23. Found: C, 61.85; H, 3.92; N, 4.29.
2H). 13C NMR (100 MHz, CDCl3):
d 12.6, 14.7, 61.0, 63.2,
118.8, 121.3, 123.0, 124.3, 125.7, 126.5, 127.3, 128.8, 130.5,
133.0, 138.0, 141.7, 160.0, 166.2.
5.16. Dimethyl-1-(4-(2,3-bis(methoxycarbonyl)-5-phenyl-1H-
pyrrol-1-yl)phenyl)-5-(4-bromophenyl)-1H-pyrrole-2,3-
dicarboxylate (Table 3, entry 4)
5.11. Dimethyl 1-benzyl-5-phenyl-1H-pyrrole-2,3-
dicarboxylate (Table 2, entry 11)
Yellow oil [28d]. IR (KBr): nmax ¼ 2931, 1725, 1497, 1451,
Mp 89e91 ꢁC. IR (KBr): nmax ¼ 2945, 1763, 1438, 1351,
1355, 1295, 1077, 1005, 829, 797, 753 cmꢀ1
.
1H NMR
1287, 1115, 855, 805, 755 cmꢀ1. 1H NMR (400 MHz, CDCl3):
(400 MHz, CDCl3):
d
3.68 (s, 3H), 3.72 (s, 3H), 5.53 (s, 2H),
d
3.60 (s, 6H), 3.64 (s, 6H), 7.3 (s, 2H), 7.46 (td, J ¼ 7.1, 1.6 Hz,
7.22 (m, 2H), 7.34 (td, J ¼ 7.5, 1.2 Hz, 2H), 7.46e7.49 (m, 3H),
1H), 7.54 (td, J ¼ 6.8, 1.4 Hz, 2H), 7.60e7.62 (m, 4H), 7.67 (d,
7.63e7.66 (m, 2H), 7.71 (d, J ¼ 9.0 Hz, 2H). 13C NMR
J ¼ 8.8 Hz, 2H), 7.85e7.89 (m, 4H). 13C NMR (100 MHz,
(100 MHz, CDCl3):
d
51.2, 52.4, 52.8, 120.7, 124.2, 125.6,
CDCl3): d 51.2, 52.8, 116.7, 118.6, 120.7, 122.3, 124.3, 126.8,
126.9, 127.1, 127.2, 128.8, 129.2, 130.9, 132.5, 139.0, 161.5,
167.8.
128.1, 128.8, 129.2, 132.1, 138.0, 138.6, 140.3, 160.8, 166.6.
Anal. Calcd. for C34H27BrN2O8: C, 60.81; H, 4.05; N, 4.17.
Found: C, 60.71; H, 4.09; N, 4.23.
5.12. Dimethyl 1-methyl-5-phenyl-1H-pyrrole-2,3-
dicarboxylate (Table 2, entry 12)
5.17. Dimethyl-1-(4-(2,3-bis(methoxycarbonyl)-5-
(naphthalen-2-yl)-1H-pyrrol-1-yl)phenyl)-5-phenyl-1H-
pyrrole-2,3-dicarboxylate (Table 3, entry 5)
Yellow oil [28f]. IR (KBr): nmax ¼ 2928, 1731, 1501, 1435,
1339, 1288, 1081, 1012, 841, 805, 751 cmꢀ1 1H NMR
.
(400 MHz, CDCl3):
d
3.62 (s, 3H), 3.66 (s, 3H), 3.86 (s, 3H),
Mp 97e99 ꢁC. IR (KBr): nmax ¼ 2935, 1741, 1501, 1459,
7.02 (s, 1H), 7.25 (t, J ¼ 8.4 Hz, 2H). 7.32e7.38 (m, 1H), 7.46
1359, 1305, 1081, 1005, 831, 797, 753 cmꢀ1 1H NMR
.
(d, J ¼ 8.4 Hz, 2H). 13C NMR (100 MHz, CDCl3):
d
30.1, 52.1,
(400 MHz, CDCl3): d 3.64 (s, 6H), 3.69 (s, 6H), 7.29 (s, 2H),
Please cite this article in press as: M. Soltani, et al., Convenient synthesis of polysubstituted pyrroles and symmetrical and
unsymmetrical bis-pyrroles catalyzed by H3PW12O40
,
Comptes Rendus Chimie (2016), http://dx.doi.org/10.1016/
j.crci.2015.11.006

8
M. Soltani et al. / C. R. Chimie xxx (2016) 1e9
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7.43e7.55 (m, 4H), 7.62e7.64 (m, 2H), 7.82 (t, J ¼ 6.7 Hz,
4H), 7.90 (d, J ¼ 7.8 Hz, 2H), 7.97 (dd, J ¼ 8.6, 1.56 Hz, 2H),
8.40 (s, 2H). 13C NMR (100 MHz, CDCl3):
d 53.0, 54.4, 118.6,
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120.2, 122.2, 123.9, 126.8, 127.2, 127.8, 128.4, 128.5, 128.8,
129.6, 130.2, 130.9, 132.5, 134.5, 135.6, 139.7, 161.2, 166.1.
Anal. Calcd. for C38H30N2O8: C, 71.02; H, 4.71; N, 4.36.
Found: C, 71.14; H, 4.75; N, 4.28.
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5.18. Tetramethyl-1,10-(1,3-phenylene)bis(5-phenyl-1H-
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Yellow oil. IR (KBr): nmax ¼ 2945, 1751, 1461, 1367, 1275,
1105, 1005, 843, 805, 755 cmꢀ1. 1H NMR (400 MHz, CDCl3):
ꢁꢀ
ꢁ
ꢀ
ꢀ
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3.63 (s, 6H), 3.66 (s, 6H), 7.30e7.34 (m, 4H), 7.35e7.39 (m,
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5.19. Tetramethyl-1,10-(1,3-phenylene)bis(5-(4-bromophenyl)-
1H-pyrrole-2,3-dicarboxylate) (Table 3, entry 7)
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CDCl3):
d 52.1, 54.5, 117.5, 118.6, 121.5, 123.3, 124.1, 127.4,
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Acknowledgments
The authors are grateful to the Research Council of the
University of Isfahan for financial support of this work.
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unsymmetrical bis-pyrroles catalyzed by H3PW12O40
,
Comptes Rendus Chimie (2016), http://dx.doi.org/10.1016/
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