Fe+3-Montmorillonite K10, as effective, eco-friendly, and reusable catalyst for the synthesis of bis(1H-indol-3-yl)methanes under grinding condition

Article abstract of DOI:10.1134/S1070363215120361

Bis(indoyl)methanes have been synthesized via electrophilic reaction of indole and aldehydes in excellent yields under mild reaction conditions in the presence of Fe⁺³-montmorillonite K10 as catalyst. The catalyst can be recovered and recycled in subsequent reactions without any apparent loss of activity.

Full text of DOI:10.1134/S1070363215120361

ISSN 1070-3632, Russian Journal of General Chemistry, 2015, Vol. 85, No. 12, pp. 2861–2866. © Pleiades Publishing, Ltd., 2015.
Fe+3-Montmorillonite K10, as Effective, Eco-Friendly,
and Reusable Catalyst for the Synthesis
of Bis(1H-indol-3-yl)methanes under Grinding Condition1
L. Z. Fekria, M. Nikpassandb, and M. Kohansala
a Department of Chemistry, Payame Noor University, PO Box 19395-3697 Tehran, Iran
e-mail: chem_zare@yahoo.com
b Department of Chemistry, Islamic Azad University, Rasht Branch, Rasht, Iran
Received July 1, 2015
Abstract—Bis(indoyl)methanes have been synthesized via electrophilic reaction of indole and aldehydes in
excellent yields under mild reaction conditions in the presence of Fe+3-montmorillonite K10 as catalyst. The
catalyst can be recovered and recycled in subsequent reactions without any apparent loss of activity.
Keywords: diindolylmethanes, Fe+3-montmorillonite K10, grind, reusable
DOI: 10.1134/S1070363215120361
INTRODUCTION
However, several of the reported protocols suffer
from significant practical limitations, such as the use
of expensive reagents, long reaction time, low yield of
the products, and the use of microwave or ultrasonic
apparatus, which are not always available in organic
chemistry laboratories. Consequently, new procedures
free from the above drawbacks are desirable.
Diindolylmethane (DIM) [or bis(indolyl)methane]
is the most active cruciferous substance for promoting
beneficial estrogen metabolism in women and men [1].
DIM increases the body’s natural metabolism of
hormones and promotes good estrogen (2-hydroxy-
estrogen) [1]. This indole antioxidant is patented for
alleviating symptoms of fibromyalgia [1]. DIM is an
effective cancer prevention agent owing to its ability to
modulate certain cancer-causing estrogen metabolites
[1]. Scientists have demonstrated that DIM induces the
apoptosis in human cancer cells [2] and may also
normalize abnormal cell growth associated with cervical
dysplasia [3]. DIM is proven to have significant
physiological activity [4] and may be successfully
applied for preventation of breast cancer [5]. There-
fore, indole and its derivatives have been a topic of
research interest.
RESULTS AND DISCUSSION
In continuation of our ongoing studies on the
synthesis of heterocyclic and pharmaceutical com-
pounds at mild and practical protocols [22–26], we
report herein our experimental results obtained in
synthesizing diindolylmethanes by the electrophilic
reaction of indole and various substituted aldehydes
under solvent-free (grinding) conditions (Scheme 1).
To the best of our knowledge, data on the synthesis of
diindolylmethanes in the presence of Fe+3-montmorillo-
nite K10 under the grinding conditions are lacking
from the literature.
Numerous methods of the preparation of bis-
indolylmethanes have been reported in the literature
employing protic [6] and Lewis acids, such as LiClO4
[7], InCl3 [8], lanthanide triflates [9], NBS [10], I2
[11], KHSO4 [12], montmorillonite K10 [13], HY-
zeolite [14], [RE(PFO)3] [15], NaHSO4/amberlyst-15
[16], CuBr2 [17], sulfamic acid [18–20], and ZrCl4
[21].
In an initial endeavor, 1a, 2 equiv. of indole 2 and
Fe+3-montmorillonite K10 (Fe+3–K10) were pulverized
with a pestle. After 4 min, 94% of the product was
obtained. The reaction was performed in the presence
of various aldehydes and the scope and generality of
this promoter was determined. To improve the reaction
efficiency, hydrazone 4a, 2 equiv. of indole 2, and
Fe+3–K10 were pulverized with a pestle. The progress
1 The text was submitted by the authors in English.
2861

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FEKRI et al.
Scheme 1. Synthesis of diindolylmethanes in the presence of Fe+3-montmorillonite K10 under grinding conditions.
Procedure a;
Fe+3-montmorillonite K10
O
+ 2
+ 2
Grinding
R
R
H
N
H
1
2
2
Fe+3-montmorillonite K10
Grinding
HN
NH
R
NNH
3
N
H
4
of a reaction was monitored by thin-layer chromato-
graphy (TLC). After 0.5 min of reaction, 98% of the
product was obtained. The results are summarized in
Table 1.
and higher yield than the synthesis from aldehyde. It
seems that the conversion of aldehyde to hydrazone
assists nucleophilic addition of indoles to aldehyde.
The efficiency of Fe+3-montmorillonite K10 in the
synthesis of diindolylmethanes under the grinding condi-
tions (time, yield, and reaction conditions) is given in
On the other hand, the synthesis of diindolyl-
methanes from hydrazone gave shorter reaction time
Table 1. Grinding-mediated synthesis of diindolylmethanes using Fe+3-montmorillonite K10
Procedure a
Procedure b
mp, °C
calculated
Producta
Aldehyde
Benzaldehyde
time, min
yield, %b
time, min
yield, %b
found
122–123
219–221
75–77
3a
3b
3c
3d
3e
3f
4
2
2
6
8
6
2
2
8
4
5
8
5
2
5
5
94
0.50
0.33
0.33
1.00
1.50
2.00
0.33
0.33
2.00
0.33
0.33
2.00
2.00
1.00
2.50
1.00
98
125–127 [27a]
220–222 [27b]
77–81 [27b]
120–122 [21]
–
4-Nitrobenzaldehyde
4-Clorobenzaldehyde
4-Hydroxybenzaldehyde
2- Hydroxybenzaldehyde
4-Methylbenzaldehyde
4-Bromobenzaldehyde
4-Fluorobenzaldehyde
2-Methoxybenzaldehyde
3- Nitrobenzaldehyde
2,4-diClorobenzaldehyde
Cinnamaldehyde
96
99
95
97
92
94
120–122
103–105
93–94
89
93
90
94
94–96 [27c]
110–112 [27d]
–
3g
3h
3i
94
96
111–113
73–74
94
95
87
92
133–134
266–267
100–102
94–96
134–136 [21]
265–266 [27a]
103–105 [21]
96–98 [21]
210–212 [27d]
67–69 [21]
–
3j
93
95
3k
3l
94
96
90
93
3m N,N-diMethylbenzaldehyde
91
94
211–213
68–70
3n
3o
3p
Pentanal
89
94
Pyridinecarbaldehyde
2-Thiophenecarbaldehyde
91
93
90–91
90
95
185–186
185–188 [27d]
a
All products were characterized by their physical constant, comparison with authentic samples, and by IR and NMR spectroscopies.
Yields are given for the case of aldehyde.
b
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Fe+3-MONTMORILLONITE K10 AS EFFECTIVE, ECO-FRIENDLY, AND REUSABLE CATALYST
2863
Table 2. The efficiency of Fe+3-montmorillonite K10 and other catalysts
Catalyst
[bmim]BF4
Condition
Time, min
Yield, %
90
References
[28]
Room temperature
Room temperature
Room temperature
Room temperature
Room temperature
Reflux
270
450
120
2
Zeokarb-225
Zeolite
95
[29]
80
[1]
HClO4–SiO2
H3PMo12O40
Schiff Base complex
Fe+3–K10
94
[30]
19
5
93
[31]
92
[32]
Procedure a, grinding
Procedure b, grinding
4
94
This work
This work
Fe+3–K10
0.5
98
Table 2, as compared with the efficiency of other
catalysts. It is clear from Table 2 that our method is
simpler, more efficient, and takes less time.
chromatography (TLC) using EtOAc: petroleum ether
(2 : 1) as eluent. The conditions of the reaction are
given in Table 2. After the reaction was complete, the
product was extracted with CHCl3 (3 × 10 mL) and
insoluble catalyst was removed by filtration. The
resulting crude material was purified by recrystal-
lization from EtOH to obtain pure products. All
synthesized compounds are unknown and were charac-
terized by their physical constants, comparison with
In addition to the simplicity and excellent results,
the significant advantage of the process is the
simplicity of the product isolation, solvent-free condi-
tions instead of the use of a carcinogenic solvent, and
the possibility to recycle Fe+3-montmorillonite K10.
After the reaction was complete, the product was
easily extracted by CHCl3. The catalyst was washed
with CHCl3/acetone and activated at 120°C. The
recycled catalyst was examined in the next run. Study-
ing the synthesis of 3a, as model substrate, showed
that the recovered catalyst could be successively
recycled in six runs, with the yield preserved.
1
authentic samples, IR, H NMR, and 13C NMR spec-
troscopies, and by elemental analysis.
3,3'-[(Phenyl)methylene]bis(1H-indole) (3a). mp
122–123°C, IR spectrum (KBr), ν, cm–1: 3396, 3049,
1
2867, 1602, 1537, 1450, 1338. H NMR spectrum
(400 MHz, CDCl3), δH, ppm: 5.93 s (1H), 6.73 s (2H),
7.10–7.37 m (12H), 7.57–7.60 m (1H), 7.95 br.s (2H).
13C NMR spectrum (100 MHz, CDCl3), δC, ppm: 33.7,
112.1, 112.9, 116.7, 118.9, 122.2, 125.6, 127.3, 127.8,
129.6, 132.8, 139.0, 146.7. Calculated, %. C 85.68; H
5.63; N 8.69. C23H18N2. Found, %: C 85.65; H 5.74; N
8.66.
EXPERIMENTAL
Materials and measurements. The melting points
were measured on an Electrothermal 9100 apparatus.
IR spectra were determined on a Shimadzu IR-470
1
spectrometer. H NMR and 13C NMR spectra were
recorded on a Bruker DRX-500 Avance spectrometer.
We used DMSO-d6 or CDCl3 as solvent and TMS as
internal standard. Chemicals were purchased from
Merck and Fluka. All solvents used were dried and
distilled, according to the standard procedures. All
yields refer to isolated products.
3,3'-[(4-Nitrophenyl)methylene]bis(1H-indole) (3b).
mp 219–221°C, IR spectrum (KBr), ν, cm–1: 3390,
3058, 2856, 1652, 1558, 1506, 1338. H NMR spec-
1
trum (400 MHz, CDCl3), δH, ppm: 6.01 s (1H), 6.70
d.d (2H, J = 0.8 Hz, J = 2.4 Hz), 7.05 t (2H, J =
8 Hz), 7.22 t (2H, J = 7.2 Hz), 7.36 d (2H, J = 7.6 Hz),
7.41 d (2H, J = 7.6 Hz), 7.52 d (2H, J = 8.4 Hz), 8.04
br.s (2H, NH), 8.12 d (2H, J = 8 Hz). 13C NMR
spectrum (100 MHz, DMSO-d6), δC, ppm: 32.3, 111.8,
114.6, 117.6, 121.8, 123.8, 124.4, 126.3, 127.0, 132.6,
136.2, 146.2, 148.5. Calculated, %: C 75.19; H 4.66; N
11.44. C23H18N2. C23H17N3O2 Found, %: C 75.28; H
4.51; N 11.60.
General procedure for the preparation of diindol-
ylmethanes. Into a mortar, substituted benzaldehyde 1
(1 mmol) or substituted hydrazone 4 (1 mmol), indole
2 (2 mmol, 0.28 g), and Fe+3-montmorillonite K10
(0.1 g) were added. The mixture was pulverized with a
pestle and entered a spontaneous reaction. The
progress of a reaction was monitored by thin-layer
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 12 2015

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FEKRI et al.
3,3'-[(4-Chlorophenyl)methylene]bis(1H-indole)
(1H), 6.46-6.78 m (4H), 7.02–7.45 m (10H), 7.56 br.s
(2H, NH). 13C NMR (100 MHz, CDCl3), δC, ppm:
35.2, 109.5, 111.2, 119.1, 119.9, 123.2, 125.8, 126.1,
126.8, 129.1, 132.9, 135.4, 145.1. Calculated, %: C
68.84; H 4.27; N 6.98. C23H17BrN2. Found, %: C 68.85;
H 4.23; N 6.95.
(3c). mp 75–77°C; IR spectrum (KBr), ν, cm–1: 3404,
1
3049, 2966, 1616, 1560, 1485, 1452. H NMR spec-
trum (400 MHz, CDCl3), δH, ppm: 5.88 s (1H), 6.66
d.d (2H, J = 1.2 Hz, J = 2.4 Hz), 7.03 t (2H, J =
7.2 Hz), 7.20 t (2H, J = 8.0 Hz), 7.24–7.37 m (2H),
7.30 d (2H, J = 2.0 Hz), 7.38 d (4H, J =7.6 Hz), 7.96
br.s (2H). 13C NMR spectrum (100 MHz, CDCl3), δC,
ppm: 33.2, 109.4, 115.3, 117.2, 118.4, 119.1, 121.0,
121.9, 124.5, 127.8, 129.1, 135.6, 147.1. Calculated,
%: C 77.41; H 4.80; N 7.85. C23H17ClN2. Found, %: C
77.48; H 4.81; N 7.78.
3,3'-[(4-Fluorophenyl)methylene]bis(1H-indole)
(3h). mp 73–74°C. IR spectrum (KBr), ν, cm–1: 3440,
1
3060, 2902, 1600, 1500, 1476, 1454, 1344. H NMR
spectrum (400 MHz, CDCl3), δH, ppm: 5.61 s (1H),
7.72 d (2H, J = 7.8 Hz), 7.90 br.s (2H, NH), 8.15–8.25
m (10H), 8.36 d (2H, J = 7.8 Hz). 13C NMR spectrum
(100 MHz, CDCl3), δC, ppm: 32.8, 111.2, 112.4, 115.1,
115.9, 123.6, 124.2, 127.8, 128.2, 129.5, 133.4, 137.9,
145.0. Calculated, %: C 68.84; H 4.27; N 6.98.
C23H17BrN2. Found, %: C 68.85; H 4.23; N 6.95.
3,3'-[(4-Hydroxyphenyl)methylene]bis(1H-indole)
(3d). mp 120–122°C; IR spectrum (KBr), ν, cm–1:
1
3406, 3051, 2935, 1649, 1595, 1452, 1338, 1211. H
NMR spectrum (400 MHz, CDCl3), δH, ppm: 5.67 s
(1H), 6.54–6.79 m (4H), 7.23 d (2H, J = 7.5 Hz), 7.56
d (2H, J = 7.5 Hz), 8.04–8.23 m (2H), 8.31 t (2H, J =
7.8 Hz), 7.37 d (2H, J = 7.6 Hz), 7.93 br.s (2H, NH),
9.35 br.s (1H, OH). 13C NMR spectrum (100 MHz,
CDCl3), δC, ppm: 31.5, 112.1, 112.7, 115.3, 116.1, 118.8,
124.2, 125.6, 127.8, 128.9, 134.2, 143.6, 147.1. Cal-
culated, %: C 81.63; H 5.36; N 8.28. C23H18N2O.
Found, %: C 81.48; H 5.31; N 8.22.
3,3'-[(2-Methoxyphenyl)methylene]bis(1H-indole)
(3i). mp 134–136°C. IR spectrum (KBr), ν, cm–1:
1
3410, 3063, 1512, 1432, 1256, 1109. H NMR spec-
trum (400 MHz, CDCl3), δH, ppm: 3.32 s (3H), 6.54 s
(1H), 6.87 d (2H, J = 7.8 Hz), 7.27–7.56 m (12H), 7.92
br.s (2H, NH). 13C NMR spectrum (100 MHz, CDCl3),
δC, ppm: 37.0, 59.6, 110.2, 115.4, 118.0, 121.4, 123.7,
126.9, 127.0, 129.0, 129.9, 133.1, 135.2, 139.8, 143.2,
146.2. Calculated, %: C 81.79; H 5.72; N 7.95.
C24H20N2O. Found, %: C 81.85; H 5.76; N 7.99.
3,3'-[(2-Hydroxyphenyl)methylene]bis(1H-indole)
(3e). mp 103–105°C. IR spectrum (KBr), ν, cm–1:
1
3406, 3051, 2935, 1649, 1595, 1452, 1338, 1211. H
3,3'-[(3-Nitrophenyl)methylene]bis(1H-indole)
(3j). mp 266–267°C. IR spectrum (KBr), ν, cm–1:
NMR spectrum (400 MHz, CDCl3), δH, ppm: 6.24 s
(1H), 6.87 d (2H, J = 8.5 Hz), 6.90 d (2H, J = 8.5 Hz),
7.52–7.71 m (10H), 7.92 br.s (2H, NH), 9.45 br.s (1H,
OH). 13C NMR spectrum (100 MHz, CDCl3), δC, ppm:
36.2, 109.8, 113.2, 115.4, 125.2, 125.7, 127.1, 127.8,
129.3, 131.0, 132.8, 133.1, 137.4, 145.1, 146.9. Cal-
culated, %: C 81.63; H 5.36; N 8.28. C23H18N2O.
Found, %: C 81.62; H 5.30; N 8.24.
1
3346, 3036, 2948, 1530, 1458, 1355, 1132. H NMR
spectrum (400 MHz, CDCl3), δH, ppm: 6.25 s (1H),
6.67 t (2H, J = 7.6 Hz), 7.17 t (2H, J = 7.5 Hz), 7.32–
7.56 m (6H), 7.87 d (2H, J = 7.7 Hz), 8.02 br.s (2H,
NH), 8.13 t (1H, J = 1.3 Hz), 8.26 t (1H, J = 1.8 Hz).
13C NMR spectrum (100 MHz, CDCl3), δC, ppm: 38.1,
111.8, 117.6, 119.0, 119.5, 121.1, 123.7, 124.7, 125.2,
128.9, 131.5, 135.2, 138.2, 143.1, 147.2, 149.9. Cal-
culated, %: C 81.79; H 5.72; N 7.95. C24H20N2O.
Found, %: C 81.85; H 5.76; N 7.99.
3,3'-[(4-Methylphenyl)methylene]bis(1H-indole)
(3f). mp 93–94°C. IR spectrum (KBr), ν, cm–1: 3402,
1
3046, 2910, 1616, 1506, 1456, 1338, 1218. H NMR
spectrum (400 MHz, CDCl3), δH, ppm: 2.32 s (3H),
5.65 s (1H), 6.54–6.78 m (12H), 7.67 d (2H, J =
8.2 Hz), 7.98 br.s (2H, NH). 13C NMR spectrum
(100 MHz, CDCl3), δC, ppm: 24.7, 32.3, 111.3, 111.7,
116.4, 117.2, 121.6, 123.8, 125.7, 129.0, 129.9, 131.2,
135.7, 145.6. Calculated, %: C 85.68; H 5.99; N 8.33.
C24H20N2. Found, %: C 85.55; H 5.88; N 8.24.
3,3'-[(2,4-Dichlorophenyl)methylene]bis(1H-indole)
(3k). mp 100–102°C. IR spectrum (KBr), ν, cm–1:
3410, 3103, 2965, 1448, 1355, 1189, 1092. H NMR
1
spectrum (400 MHz, CDCl3), δH, ppm: 6.35 s (1H),
6.49 t (2H, J = 7.8 Hz), 7.19 t (2H, J = 7.9 Hz), 7.35–
7.66 m (6H), 7.97 d (2H, J = 7.8 Hz), 8.02 br.s (2H,
NH), 8.13 s (1H). 13C NMR spectrum (100 MHz,
CDCl3), δC, ppm: 38.1, 111.8, 117.6, 119.0, 119.5,
121.1, 123.7, 124.7, 125.2, 128.9, 131.5, 135.2, 138.2,
147.2, 149.9. Calculated, %: C 70.60; H 4.12; N 7.16.
C23H16Cl2N2. Found, %: C 70.65; H 4.16; N 7.24.
3,3'-[(4-Bromophenyl)methylene]bis(1H-indole)
(3g). mp 111–113°C. IR spectrum (KBr), ν, cm–1:
1
3402, 3040, 2960, 1616, 1540, 1480, 1446, 1338. H
NMR spectrum (400 MHz, CDCl3), δH, ppm: 5.54 s
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Fe+3-MONTMORILLONITE K10 AS EFFECTIVE, ECO-FRIENDLY, AND REUSABLE CATALYST
2865
(E)-3,3'-(3-Phenylprop-2-ene-1,1-diyl)bis(1H-
indole) (3l). mp 94–96°C. IR spectrum (KBr), ν, cm–1:
3450, 3100, 2960, 1590, 1470, 1030. 1H NMR
spectrum (400 MHz, CDCl3), δH, ppm: 5.78 s (1H),
6.38 d (1H, J = 16.6 Hz), 6.56 d (1H, J = 16.6 Hz),
7.17 t (4H, J = 7.6 Hz), 7.45–7.68 m (8H), 7.82 t (3H,
J = 7.9 Hz), 8.07 br.s (2H, NH). Calculated, %: C
70.60; H 4.12; N 7.16. C25H20N2. Found, %: C 70.63;
H 4.14; N 7.11.
CONCLUSIONS
In conclusion, Fe+3-montmorillonite K10, as a mild
and efficient catalyst, was studied in the synthesis of
diindolylmethanes under grinding conditions. The
method applies inexpensive, nontoxic, easy-to-handle,
and reusable catalyst, proceeds for a shorter time, gives
products in high yield and with a better purity, uses a
simple work-up procedure, and is ecologically friendly,
which makes it remarkably advantageous over other
methods.
4-[Di(1H-indol-3-yl)methyl]-N,N-dimethylaniline
(3m). mp 211–213°C. IR spectrum (KBr), ν, cm–1:
3348, 3154, 1384, 1255, 1063. 1H NMR spectrum (400
MHz, CDCl3), δH, ppm: 2.53 s (6H), 5.61 s (1H), 7.72
d (2H, J = 7.8 Hz), 8.02 br.s (2H, NH), 8.15–8.25 m
(10H), 8.36 d (2H, J = 7.8 Hz). 13C NMR spectrum
(100 MHz, CDCl3), δC, ppm: 32.8, 43.5, 111.2, 112.4,
115.9, 123.6, 124.2, 127.8, 128.2, 129.5, 133.4, 137.9,
143.1, 145.0. Calculated, %: C 82.16; H 6.34; N 11.50.
C25H23N3. Found, %: C 82.24; H 6.33; N 11.57.
ACKNOWLEDGMENTS
The study was financially supported by the Research
Council of the Payame Noor University, Rudsar branch.
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70°C. IR spectrum (KBr), ν, cm–1: 3465, 3108, 3060,
1
2980, 1600, 1546, 1250, 1060. H NMR spectrum
(400 MHz, CDCl3), δH, ppm: 0.87 t (3H, J = 6.8 Hz),
1.37–1.63 m (4H) , 2.31 m (2H), 4.64 t (1H, J =
6.8 Hz), 6.58 d (2H, J = 4.5 Hz), 7.07–7.81 m (6H),
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22.3, 24.5, 32.8, 111.2, 123.6, 124.2, 127.8, 129.5,
133.4, 137.9, 145.0. Calculated, %: C 83.40; H 7.33; N
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3,3'-(Pyridin-4-yl methylene)bis(1H-indole) (3o).
mp 185–186°C. IR spectrum (KBr), ν, cm–1: 3465,
1
3006, 2987, 1477, 1365, 1112. H NMR spectrum
7. Yadav, J.S., Reddy, B.V.S., Murthy, Ch. V.S.R.,
(400 MHz, CDCl3), δH, ppm: 6.24 s (1H), 7.02–7.27 m
(10H), 7.84–7.90 m (2H), 7.88 br.s (2H, NH), 8.22–
8.30 m (2H). 13C NMR spectrum (100 MHz, CDCl3),
δC, ppm: 38.1, 111.8, 119.0, 123.7, 124.7, 128.9, 131.5,
135.2, 138.2,143.4, 147.2, 149.9. Calculated, %: C
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mp 90–91°C. IR spectrum (KBr), ν, cm–1: 3343, 3175,
1546, 1455, 1256, 1089. 1H NMR spectrum (400 MHz,
CDCl3), δH, ppm: 6.24 s (1H), 7.02–7.27 m (10H),
7.84 s (2H), 7.88 br.s (2H, NH), 8.32 s (1H). 13C NMR
spectrum (100 MHz, CDCl3), δC, ppm: 38.1, 111.8,
117.6, 119.0, 121.1, 124.7, 128.9, 131.5, 135.2, 138.2,
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