Application of {[4,4′-BPyH][C(CN)3]2} as a Bifunctional Nanostructured Molten Salt Catalyst for the Preparation of 2-Amino-4 H -chromene Derivatives under Solvent-Free and Benign Conditions

Article abstract of DOI:10.1055/s-0035-1561345

The bifunctional nanostructured molten salt [4,4′-bipyridine]-1,1′-diium tricyanomethanide has been employed as a highly efficient and powerful catalyst for the preparation of 2-amino-4H-chromenes. A wide variety of aromatic aldehydes was condensed with m

Full text of DOI:10.1055/s-0035-1561345

SYNLETT
0
9
3
6
-
5
2
1
4
1
4
3
7
-
2
0
9
6
© Georg Thieme Verlag Stuttgart · New York
2016, 27, A–E
letter
A
M. A. Zolfigol et al.
Letter
Synlett
Application of {[4,4′-BPyH][C(CN)3]2} as a Bifunctional Nanostruc-
tured Molten Salt Catalyst for the Preparation of 2-Amino-4H-
chromene Derivatives under Solvent-Free and Benign Conditions
Mohammad Ali Zolfigol*
Meysam Yarie
Saeed Baghery
Faculty of Chemistry, Bu-Ali Sina University,
Hamedan 6517838683, Iran
zolfi@basu.ac.ir
mzolfigol@yahoo.com
Received: 02.12.2015
Accepted after revision: 30.12.2015
Published online: 02.02.2016
Several homogeneous and heterogeneous catalysts have
been employed for the synthesis of 2-amino-4H-chromene
derivatives,
including
aminosilane-modified
Fe3O4
DOI: 10.1055/s-0035-1561345; Art ID: st-2015-d0934-l
nanoparticles,15 potassium phthalimide-N-oxyl,16 gel en-
trapped DABCO,17 Fe3O4-chitosan MNPs,18 Mg/Al-HT,19
TAFMC-1,20 nanozeolite clinoptilolite,21 anhydrous sodium
carbonate,22 TPOP-2,23 a nano-polypropylenimine dendrim-
er,24 potassium phthalimide,25 TiCl4,26 methane sulfonic ac-
id,27 InCl3,28 γ-alumina,29 and tetramethylguanidine.30 Al-
though, these reported protocols have their merits, they
also suffer from one or more drawbacks. Hence, the devel-
opment of milder methods that can be conducted under
solvent-free conditions employing environmentally benign
catalysts is still a valid goal.
Abstract The bifunctional nanostructured molten salt [4,4′-bipyri-
dine]-1,1′-diium tricyanomethanide has been employed as a highly effi-
cient and powerful catalyst for the preparation of 2-amino-4H-
chromenes. A wide variety of aromatic aldehydes was condensed with
malononitrile and resorcinol, 1-naphthol or 2-naphthol under mild and
solvent-free conditions. This protocol has the advantages of short reac-
tion times, high to excellent yields, and straightforward workup.
Key words multicomponent reactions, molten salt, ionic liquids, sol-
vent-free conditions
The success of multicomponent reactions (MCRs) has
persuaded both academic and industrial communities to
use this approach to access molecular diversity. The advan-
tages of this methodology include fabrication of various
new chemical bonds in one-pot with high atomic economy,
a reduction in both the number of by-products formed and
the number of purification steps required, and the ease of
workup.1
2-Amino-4H-chromenes have been applied to the treat-
ment of rheumatoid arthritis, psoriasis, cancer, amyo-
trophic lateral sclerosis, Parkinson’s disease, Huntington’s
disease, Alzheimer’s disease, Down’s syndrome, AIDS,
schizophrenia, and myoclonus,2 as well as demonstrating
biological properties such as antiviral,3 antimicrobial,4 anti-
proliferative,5 mutagenic,6 antitumor,7 pheromonal,8 and
central nervous system activity.9 Furthermore, 2-amino-
4H-chromene derivatives have been exploited as laser
dyes,10 optical brighteners,11 fluorescence markers,12 pig-
ments,13 cosmetics, and biodegradable agrochemicals.14
Ionic liquids (ILs) and molten salts (MSs) play key roles
in extraction, as reactive catalytic supports and spatial de-
vices, and in biotransformations.31 In general, ILs and MSs
differ with respect to the region of their melting point.
Whereas ionic liquids melt at or near ambient temperature,
molten salts or fused salts tend to have higher melting
points, generally considered to be over 100 °C.32 Recently,
Atkin et al. considered structure and nanostructure in ionic
liquids33 and a reductive Friedel–Crafts alkylation was stud-
ied without using external reductant.34 Following our pre-
vious studies on the design, synthesis, and applications of
nano-ionic liquids and molten salts in organic reactions35
and as a part of our continuing investigations on strategies
for one-pot multicomponent reactions for the preparation
of pharmaceutical and biological consequential mole-
cules,36 herein, we report the preparation of a wide range of
2-amino-4H-chromenes through the reaction of various
aryl aldehydes, malononitrile, resorcinol, 1-naphthol or
2-naphthol under mild conditions in the presence of the
first bifunctional nanostructured molten salt, {[4,4′-
BPyH][C(CN)3]2}.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–E

B
M. A. Zolfigol et al.
Letter
Synlett
Table 1 Effect of Catalyst Loading and Influence of Solvent for the
Initially, [4,4′-bipyridin]-1,1′-diium tricyanomethanide
was produced as a bifunctional molten salt catalyst (see the
Supporting Information). The catalytic applicability of the
resulting nano-bifunctional molten salt was investigated
for the preparation of 2-amino-4H-chromene derivatives.
To optimize the reaction conditions, the condensation of 4-
chlorobenzaldehyde, malononitrile, and resorcinol (1 mmol
each) was selected as a typical reaction. The reaction was
performed with different amounts of nano-bifunctional
molten salt heated to 25–100 °C under solvent-free condi-
tions (Table 1). The best results were obtained by using
3 mg nanostructured molten salt under solvent-free condi-
tions at room temperature (entry 3). No improvement in
yield was observed on increasing either the amount of cata-
lyst or temperature. The reaction did not proceed in the ab-
sence of nanocatalyst.
Model Reaction at Room Temperaturea
Entry
Catalyst amount Solvent
(mg)
Reaction time Yield
(min)
(%)b
1
2
1
2
3
4
5
3
3
3
3
3
3
–
50
20
10
9
30
86
94
94
95
–
3
–
4
–
5
–
9
6
EtOH
H2O
CH3CN
CHCl3
n-hexane
CH2Cl2
60
60
60
80
65
55
trace
7
trace
trace
71
8
9
10
11
67
To demonstrate the generality of this methodology for
the synthesis of 2-amino-4H-chromenes, a range of aro-
matic aldehydes was condensed with malononitrile and re-
sorcinol, 1-naphthol or 2-naphthol under solvent-free con-
ditions (Table 2). For aromatic aldehydes bearing electron-
trace
a Reaction conditions: 4-chlorobenzaldehyde (1 mmol), malononitrile (1
mmol), resorcinol (1 mmol).
b Isolated yield.
Table 2 Cascade Knoevenagel–Michael Cyclocondensation Sequence for the Synthesis of 2-Amino-4H-chromene Derivatives Using {[4,4′-
BPyH][C(CN)3]2} as a Bifunctional Nanostructured Molten Salt Catalysta
Entry
Arylaldehyde
Phenol
Time (min)
Temp. (°C)
Yield (%)b
Mp (°C) [Lit.]Ref.
1
2
4-Cl
resorcinol
resorcinol
resorcinol
resorcinol
resorcinol
resorcinol
resorcinol
resorcinol
resorcinol
resorcinol
resorcinol
2-naphthol
2-naphthol
1-naphthol
1-naphthol
1-naphthol
1-naphthol
1-naphthol
1-naphthol
resorcinol
2-naphthol
1-naphthol
10
12
12
13
14
15
11
10
15
13
16
15
15
10
9
r.t.
r.t.
r.t.
r.t.
r.t.
80
80
80
80
80
80
80
80
80
80
80
80
80
80
80
80
80
94
94
91
92
89
90
94
85
91
84
89
91
90
94
93
90
93
92
85
–
239–241 [228–230]22
256–258 [256–259]15
218–220 [210–212]19
251–253 [240–241]22
121–123 [188–190]19
238–240 [230–231]22
227–229 [109–111]15
173–175 [190–192]16
219–221 [215–217]15
227–229 [215–217]19
180–182
2,4-Cl2
3
4-NO2
4
4-Br
5
3-NO2
6
benzaldehyde
4-OMe
7
8
4-(N,N-Me2)
3-OH
9
10
11
12
13
14
15
16
17
18
19
20
21
22
3,4-(OMe)2
3-OMe
4-Cl
219–221 [207–209]22
240–242 [254–255]37
239–241 [233–235]22
264–266 [259–260]37
188–190 [191]17
247–249 [240–241]25
249–251 [240–241]37
215–216 [218–219]37
–38
2,4-Cl2
4-Cl
4-CN
4-OMe
20
10
8
2-Cl
4-Br
benzaldehyde
benzaldehyde
benzaldehyde
benzaldehyde
20
120
120
120
–
–38
–
–38
a Reaction conditions: aromatic aldehyde (1 mmol), malononitrile (1 mmol), phenol derivatives (1 mmol), {[4,4′-BPyH][C(CN)3]2} as a nanostructure molten salt
catalyst (3 mg), solvent-free.
b Isolated yield.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–E

C
M. A. Zolfigol et al.
Letter
Synlett
Table 3 Synthesis of 2-Amino-7-hydroxy-4-phenyl-4H-chromene-3-carbonitrile with Nanostructured Molten Salt Catalyst and with Previously Report-
ed Catalysts
Entry
Reaction conditions
Catalyst loading
Time (min)
Yield (%)
Ref.
this work
1
2
3
4
5
6
7
8
{[4,4′-BPyH][C(CN)3]2}, solvent-free, 80 °C
POPINO, H2O, reflux
3 mg
15
20
90
90
92
95
86
92
87
82
1.5 mol%
16
39
19
20
21
23
24
Na2CO3, grinding, 50 °C
30
Mg/Al-HT, H2O, 60 °C
15 wt%
30 mg
0.01 g
240
720
15
TAFMC-1, H2O, 100 °C
Nanozeolite CP, H2O, reflux
TPOP-2, solvent-free, 80 °C
DAB-PPI G1, solvent-free, 110 °C
40 mg
15 mol%
300
20
withdrawing groups (entries 1–5), the reaction reached
completion relatively rapidly, but for benzaldehyde and ar-
omatic aldehydes, with electron-releasing groups, it was
found that the reaction did not proceed at room tempera-
ture. Accordingly, as a model, we tested the reaction of
benzaldehyde, malononitrile, and resorcinol at different
temperatures; the best result was achieved at 80 °C, giving
a product yield of 90% in 15 minutes. Hence, for benzalde-
hyde and aromatic aldehydes, bearing electron-releasing
groups, the reaction was performed at 80 °C (entries 6–19).
In a further study, to optimize the reaction conditions
for the synthesis of analogues, the condensation reaction of
benzaldehyde, ethyl cyanoacetate, and resorcinol, β-naph-
thol or α-naphthol was chosen as a model system under
solvent-free conditions at 80 °C (Table 2, entries 20–22).
However, in these cases, no product was obtained after 2
hours.
References and Notes
(1) (a) Multicomponent Reactions; Zhu, J.; Bienayme, H., Eds.;
Wiley-VCH: Weinheim, 2005. (b) Ganem, B. Acc. Chem. Res.
2009, 42, 463. (c) Domling, A.; Ugi, I. Angew. Chem. Int. Ed. 2000,
39, 3169.
(2) (a) Gao, Y.; Yang, W.; Du, D. M. Tetrahedron: Asymmetry 2012,
23, 339. (b) Konkoy, C. S.; Fisck, D. B.; Cai, S. X.; Lan, N. C.; Keana,
J. F. W. PCT Int. Appl WO 0075123, 2000; Chem. Abstr. 2001, 134,
29313a.
(3) Martinez, A. G.; Marco, L. J. Bioorg. Med. Chem. Lett. 1997, 7,
3165.
(4) Khafagy, M. M.; El-Wahas, A. H. F. A.; Eid, F. A.; El-Agrody, A. M.
Farmaco 2002, 57, 715.
(5) Dell, C. P.; Smith, C. W. European Patent Appl. EP 537949, 1993;
Chem. Abstr. 1993, 119139102d.
(6) Hiramoto, K.; Nasuhara, A.; Michiloshi, K.; Kato, T.; Kikugawa, K.
Mutat. Res., Genet. Toxicol. Environ. Mutagen. 1997, 395, 47.
(7) Mohr, S. J.; Chirigos, M. A.; Fuhrman, F. S.; Pryor, J. W. Cancer
Res. 1975, 35, 3750.
(8) Bianchi, G.; Tavaz, A. Agric. Biol. Chem. 1987, 51, 2001.
(9) Anderson, D. R.; Hegde, S.; Reinhard, E.; Gomez, L.; Vernier, W.
F.; Lee, L.; Liu, S.; Sambandam, A.; Snider, P. A.; Masih, L. Bioorg.
Med. Chem. Lett. 2005, 15, 1587.
(10) Reynolds, G. A.; Drexhage, K. H. Opt. Commun. 1975, 13, 222.
(11) Zollinger, H. Color Chemistry, 3rd ed.; Wiley-VCH: Weinheim,
2003.
The efficacy of this bifunctional nanostructured molten
salt catalyst was compared with those of other catalysts for
the
synthesis
of
2-amino-7-hydroxy-4-phenyl-4H-
chromene-3-carbonitrile. To this end, we assessed the abili-
ty of these catalysts to promote the condensation of benzal-
dehyde with malononitrile and resorcinol (Table 3). It was
found that the nanostructure molten salt catalyst compares
favorably in this reaction.
(12) Bissell, E. R.; Mitchell, A. R.; Smith, R. E. J. Org. Chem. 1980, 45,
2283.
In summary, the bifunctional nanostructure molten salt
[4,4′-bipyridine]-1,1′-diium tricyanomethanide has been
employed as a highly efficient and powerful catalyst for the
preparation of 2-amino-4H-chromenes.40
(13) Ellis, G. P. Chromenes, Harmones and Chromones, In The Chemis-
try of Heterocyclic of Compounds; Weissberger, A.; Taylor, E. C.,
Eds.; John Wiley: New York, 1977, Chap. 2, 11–13.
(14) Hafez, E. A. A.; Elnagdi, M. H.; Elagamey, A. G. A.; El-Taweel, F. M.
A. A. Heterocycles 1987, 26, 903.
(15) Safari, J.; Zarnegar, Z. J. Mol. Struct. 2014, 1072, 53.
(16) Dekamin, M. G.; Eslami, M.; Maleki, A. Tetrahedron 2013, 69,
1074.
Acknowledgment
(17) Shinde, S.; Rashinkar, G.; Salunkhe, R. J. Mol. Liq. 2013, 178, 122.
(18) Safari, J.; Javadian, L. Ultrason. Sonochem. 2015, 22, 341.
(19) Kale, S. R.; Kahandal, S. S.; Burange, A. S.; Gawandeb, M. B.;
Jayaram, R. V. Catal. Sci. Technol. 2013, 3, 2050.
(20) Kundu, S. K.; Mondal, J.; Bhaumik, A. Dalton Trans. 2013, 10515.
(21) Baghbanian, S. M.; Rezaeia, N.; Tashakkorianb, H. Green Chem.
2013, 15, 3446.
We thank Bu-Ali Sina University and Iran National Science Founda-
tion (INSF) for providing financial support (Grant Number:
94002177) to our research group.
Supporting Information
Supporting information for this article is available online at
(22) Hosseinchi Qareaghaj, O.; Mashkouri, S.; Naimi-Jamal, M. R.;
Kauppb, G. RSC Adv. 2014, 4, 48191.
http://dx.doi.org/10.1055/s-0035-1561345.
S
u
p
p
ortioInfgrmoaitn
S
u
p
p
ortiInfogrmoaitn
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–E

D
M. A. Zolfigol et al.
Letter
Synlett
(23) Kundu, S. K.; Bhaumik, A. RSC Adv. 2015, 5, 32730.
(24) Maleki, B.; Sheikh, S. RSC Adv. 2015, 5, 42997.
General Procedure for the Synthesis of 2-Amino-4H-
chromene Derivatives through
a Cascade Knoevenagel–
(25) Dekamin, M. G.; Eslami, M. Green Chem. 2014, 16, 4914.
(26) Kumar, B. S.; Srinivasulu, N.; Udupi, R. H.; Rajitha, B.; Reddy, Y.
T.; Reddy, P. N.; Kumar, P. S. J. Heterocycl. Chem. 2006, 43, 1691.
(27) Heravi, M. M.; Baghernejad, B.; Oskooie, H. A. J. Chin. Chem. Soc.
2008, 55, 659.
(28) Lakshmi, N. V.; Kiruthika, S. E.; Perumal, P. T. Synlett 2011,
1389.
(29) Maggi, R.; Ballini, R.; Sartori, G.; Sartorio, R. Tetrahedron Lett.
2004, 45, 2297.
Michael Cyclocondensation Sequence
To a mixture of aryl aldehyde (1 mmol), malononitrile (0.066 g,
1 mmol), and phenol (1 mmol) in a round-bottom flask, [4,4′-
bipyridine]-1,1′-diium tricyanomethanide (3 mg) was added
and the mixture was stirred at either room temperature (Table
2, entries 1–5) or 80 °C (entries 6–19) in the absence of solvent
for the appropriate time (Table 2). After completion of the reac-
tion as monitored by TLC (n-hexane/ethyl acetate, 2:1), ethyl
acetate (10 mL) was added and the reaction mixture was stirred
and heated to reflux for 10 min. The resulting mixture was then
washed with water (10 mL) and decanted to separate catalyst
from the other materials (the reaction mixture was soluble in
hot ethyl acetate and nanostructured molten salt catalyst was
soluble in water). The aqueous layer was decanted, separated,
and the water was removed to recover the catalyst for further
use. The organic layer was dried, filtered, the solvent was
removed, and the crude product was purified by recrystalliza-
tion from ethanol (95%) to give the pure product with high to
excellent yields (Table 2).
(30) Kalla, R. M. N.; Byeon, S. J.; Kim, M. S. H. Tetrahedron 2013, 69,
10544.
(31) (a) Dupot, J. Acc. Chem. Res. 2011, 44, 1223. (b) Plechkova, N.;
Seddon, K. Chem. Soc. Rev. 2008, 37, 123. (c) Olivier-Bourbigou,
H.; Travers, P.; Chodorge, J. A. Pet. Technol. Q. 1999, Q4, 141.
(d) Lozano, P.; de Diego, T.; Carrie, D.; Vaultier, M.; Iborra, J. L.
Biotechnol. Prog. 2003, 19, 380.
(32) Wasserscheid, P.; Keim, W. Angew. Chem. Int. Ed. 2000, 39, 3772.
(33) Hayes, R.; Warr, G. G.; Atkin, R. Chem. Rev. 2015, 115, 6357.
(34) Taheri, A.; Lai, B.; Cheng, Ch.; Gu, Y. Green Chem. 2015, 17, 812.
(35) (a) Zolfigol, M. A.; Baghery, S.; Moosavi-Zare, A. R.; Vahdat, S.
M.; Alinezhad, H.; Norouzi, M. RSC Adv. 2015, 5, 45027.
(b) Zolfigol, M. A.; Afsharnadery, F.; Baghery, S.; Salehzadeh, S.;
Maleki, F. RSC Adv. 2015, 5, 75555. (c) Zolfigol, M. A.; Baghery,
S.; Moosavi-Zare, A. R.; Vahdat, S. M. RSC Adv. 2015, 5, 32933.
(d) Zolfigol, M. A.; Baghery, S.; Moosavi-Zare, A. R.; Vahdat, S.
M.; Alinezhad, H.; Norouzi, M. RSC Adv. 2014, 4, 57662.
(36) (a) Zolfigol, M. A.; Khakyzadeh, V.; Moosavi-Zare, A. R.; Zare, A.;
Azimi, S. B.; Asgari, Z.; Hasaninejad, A. C. R. Chim. 2012, 15, 719.
(b) Zolfigol, M. A.; Khazaei, A.; Moosavi-Zare, A. R.; Zare, A.;
Asgari, Z.; Khakyzadeh, V.; Hasaninejad, A. J. Ind. Eng. Chem.
(Amsterdam, Neth.) 2013, 19, 721. (c) Moosavi-Zare, A. R.;
Zolfigol, M. A.; Zarei, M.; Zare, A.; Khakyzadeh, V. J. Mol. Liq.
2013, 186, 63. (d) Moosavi-Zare, A. R.; Zolfigol, M. A.; Zarei, M.;
Zare, A.; Khakyzadeh, V.; Hasaninejad, A. Appl. Catal., A 2013,
467, 61. (e) Moosavi-Zare, A. R.; Zolfigol, M. A.; Khaledian, O.;
Khakyzadeh, V.; Farahani, M. D.; Kruger, H. G. New J. Chem.
2014, 38, 2342. (f) Moosavi-Zare, A. R.; Zolfigol, M. A.; Daraei,
M. Synlett 2014, 25, 1173. (g) Moosavi-Zare, A. R.; Zolfigol, M. A.;
Khakyzadeh, V.; Böttcher, C.; Beyzavi, M. H.; Zare, A.;
Hasaninejad, A.; Luque, R. J. Mater. Chem. A 2014, 2, 770.
(h) Ghorbani, M.; Noura, S.; Oftadeh, M.; Gholamia, E.; Zolfigol,
M. A. RSC Adv. 2015, 5, 55303. (i) Zolfigol, M. A.; Ayazi-nas-
rabadi, R.; Baghery, S. RSC Adv. 2015, 5, 71942.
Selected Characterization Data
2-Amino-4-(4-chlorophenyl)-7-hydroxy-4H-chromene-3-
carbonitrile (Table 2, Entry 1)
Yield: 94% (0.280 g); mp 239–241 °C. FTIR (KBr): 3463, 3343,
3251, 2193, 1643, 1506, 1402, 1154, 1111 cm–1 1H NMR
.
(400.13 MHz, DMSO-d6): δ = 4.67 (s, 1 H, CH), 6.42 (d, 4J = 2 Hz,
1 H, ArH), 6.50 (dd, 3J= 8 Hz, 4J = 2 Hz, 1 H, ArH), 6.79 (d, 3J =
8 Hz, 1 H, ArH), 6.92 (s, 2 H, NH2), 7.19 (d, 3J = 8 Hz, 2 H, ArH),
3
7.37 (d, J = 8 Hz, 2 H, ArH), 9.73 (s, 1 H, OH). 13C NMR (100.61
MHz, DMSO-d6): δ = 55.8, 102.2, 112.4, 113.2, 120.5, 128.5,
129.3, 129.9, 131.2, 145.3, 148.8, 157.2, 160.2.
2-Amino-4-(4-bromophenyl)-7-hydroxy-4H-chromene-3-
carbonitrile (Table 2, Entry 4)
Yield: 92% (0.315 g); mp 251–253 °C. FTIR (KBr): 3470, 3340,
3256, 2191, 1640, 1507, 1411, 1155, 1112 cm–1 1H NMR
.
(400.13 MHz, DMSO-d6): δ = 4.66 (s, 1 H, CH), 6.42 (d, 4J =
3
2.4 Hz, 1 H, ArH), 6.50 (dd, J = 8 Hz, 4J = 2.4 Hz, 1 H, ArH), 6.80
(m, 1 H, ArH), 6.92 (s, 2 H, NH2), 7.13 (d, 3J = 8.4 Hz, 2 H, ArH),
7.50 (d, 3J = 8.4 Hz, 2 H, ArH), 9.74 (s, 1 H, OH). 13C NMR (100.61
MHz, DMSO-d6): δ = 55.7, 102.2, 112.5, 113.1, 119.7, 120.5,
129.6, 129.9, 131.5, 145.7, 148.8, 157.2, 160.2.
2-Amino-7-hydroxy-4-(3-methoxyphenyl)-4H-chromene-3-
carbonitrile (Table 2, Entry 11)
Yield: 89% (0.262 g); mp 180–182 °C. FTIR (KBr): 3446, 3340,
1
(37) Meng, X. Y.; Wang, H. J.; Wang, C. P.; Zhang, Z. H. Synth.
Commun. 2011, 41, 3477.
(38) Chaker, A.; Najahi, E.; Nepveu, F.; Chabchoub, F. Arab. J. Chem.
2013, http://dx.doi.org/10.1016/j.arabjc.2013.11.045.
(39) Javanshir, Sh.; Safari, M.; Dekamin, M. G. Sci. Iran., Trans. C 2014,
21, 742.
3219, 2192, 1641, 1508, 1410, 1154, 1115, 1048 cm–1. H NMR
(400.13 MHz, DMSO-d6): δ = 3.72 (s, 3 H, OMe), 4.59 (s, 1 H, CH),
6.41 (d, 4J = 2.4 Hz, 1 H, ArH), 6.49 (dd, 3J = 8 Hz, 4J = 2.4 Hz, 1 H,
ArH), 6.72–6.85 (m, 4 H, ArH), 6.87 (s, 2 H, NH2), 7.23 (t, 3J =
8 Hz, 1 H, ArH), 9.67 (s, 1 H, OH). 13C NMR (100.61 MHz, DMSO-
d6): δ = 54.9, 56.1, 102.1, 111.5, 112.3, 113.4, 113.6, 119.5,
120.6, 129.7, 129.8, 147.9, 148.8, 157.1, 159.3, 160.3.
(40) General Procedure for the Preparation of Nanostructured
Molten Salt {[4,4′-BPyH][C(CN)3]2}
3-Amino-1-(4-dichlorophenyl)-1H-benzo[f]chromene-2-car-
bonitrile (Table 2, Entry 13)
To an aqueous solution of tricyanomethane (0.455 g, 5 mmol, 5
mL), 4,4′-bipyridine (0.39 g, 2.5 mmol) was added and the
resulting mixture was stirred for 3 h at ambient temperature.
The solvent was then evaporated under reduced pressure. The
pale-yellow powder was dried under vacuum at 100 °C for 3 h.
The obtained pale-yellow solid was filtered, washed repeatedly
with diethyl ether to remove any unreacted starting materials,
and then dried under vacuum.
Yield: 90% (0.331 g); mp 240–242 °C. FTIR (KBr): 3463, 3324,
3190, 2200, 1661, 1589, 1407, 1237, 819 cm–1. 1H NMR (400.13
MHz, DMSO-d6): δ = 5.72 (s, 1 H, CH), 7.03 (d, 3J = 8.4 Hz, 1 H,
ArH), 7.11 (s, 2 H, NH2), 7.27 (dd, 3J = 8.4 Hz, 4J = 2 Hz, 1 H, ArH),
7.35 (d, 3J = 8.8 Hz, 1 H, ArH), 7.43–7.52 (m, 2 H, ArH), 7.58 (d,
3J = 8.4 Hz, 1 H, ArH), 7.64 (d, 4J = 2.4 Hz, 1 H, ArH), 7.94–7.99
(m, 2 H, ArH). 13C NMR (100.61 MHz, DMSO-d6): δ = 55.0, 114.0,
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–E

E
M. A. Zolfigol et al.
Letter
Synlett
118.2, 120.5, 120.6, 122.7, 123.8, 126.3, 126.6, 126.7, 127.6,
128.7, 132.6, 137.8, 142.6, 158.1, 159.9.
2-Amino-4-(4-methoxyphenyl)-4H-benzo[h]chromene-3-
carbonitrile (Table 2, Entry 16)
1 H, CH), 6.88 (d, 3J = 8.4 Hz, 2 H, ArH), 7.10 (m, 1 H, NH2 and
1 H, ArH), 7.17 (d, 3J = 8.4 Hz, 2 H, ArH), 7.56–7.66 (m, 4 H, ArH),
7.89 (d, 3J = 8 Hz, 1 H, ArH), 8.24 (d, 3J = 8 Hz, 1 H, ArH).
13C NMR (100.61 MHz, DMSO-d6): δ = 34.8, 55.7, 114.1, 116.8,
119.7, 122.5, 125.1, 127.5, 128.5, 128.7, 128.9, 129.9, 130.1,
130.8, 131.4, 131.9, 132.1, 141.7, 147.1, 159.8.
Yield: 90% (0.296 g); mp 188–190 °C. FTIR (KBr): 3415, 3324,
2194, 1663, 1604, 1509, 1377, 1253, 1104, 1023, 809 cm–1 1H
.
NMR (400.13 MHz, DMSO-d6): δ = 3.72 (s, 3 H, OMe), 4.85 (s,
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–E