Comparative study for the aqeous synthesis of new generation of diindolylmethanes using L-proline, K10 and nano-Fe3O4 under ultrasound irradiation

Article abstract of DOI:10.2174/157017812801264719

An efficient nucleophilic addition reaction of indole derivatives with various synthesized azo-linked aldehydes to afford novel derivatives of diindolylmethane was carried out using a catalytic amount of L-proline, K10 and nano-Fe₃O₄ in aqeous media.

Full text of DOI:10.2174/157017812801264719

Letters in Organic Chemistry, 2012, 9, 375-381
375
Comparative Study for the Aqeous Synthesis of New Generation of
Diindolylmethanes Using L-Proline, K10 and Nano-Fe3O4 under
Ultrasound Irradiation
Mohammad Nikpassand*,a, Leila Zareb and Mohammad R. Mousavia
aDepartment of Chemistry, Rasht Branch, Islamic Azad University, Rasht, Iran
bDepartment of Chemistry, Payame Noor University, PO Box 19395-3697 Tehran, Iran
Received November 25, 2011: Revised March 12, 2012: Accepted March 12, 2012
Abstract: An efficient nucleophilic addition reaction of indole derivatives with various synthesized azo-linked aldehydes
to afford novel derivatives of diindolylmethane was carried out using a catalytic amount of L-proline, K10 and nano-
Fe3O4 in aqeous media.
Keywords: Diindolylmethanes, indole, K10, L-proline, nano-Fe3O4.
INTRODUCTION
solvents, low yield and cumbersome product isolation
procedure. The other limitation of the diindolylmethane
synthesis is represented by the fact that the process leads to
the synthesis of preliminary diindolylmethanes using simple
aldehydes. Due to this problem, synthesis of novel
derivatives of diindolylmethanes in an efficient and versatile
method is an important aspect of organic chemistry.
Azo dyes are compounds that contain azo groups linked
to methane or aromatic sp2-hybridized C-atom. Azo dyes are
wellknown class of organic photoactive materials due to
their excellent optical switching properties, good chemical
stabilities and high solution process abilities [1, 2]. These
materials are widely used in heat transfer printing and textile
industries [3, 4] , optical data storage [5] and photo-refractive
polymer industries [6].
RESULTS AND DISCUSSION
It is well known that diindolylmethanes (DIMs) and
related compounds exhibit a wide range of biological
activities such as antibacterial and antitumor properties [7].
Diindolylmethanes are the most active cruciferous
substances for promoting beneficial estrogen metabolism in
women and men [8]. DIMs increase the body’s natural
metabolism of hormones and promote good estrogen (2-
hydroxyestrogen). This indole antioxidant is patented for
alleviating syptoms of
In continuation of our ongoing studies to synthesize of
heterocyclic and pharmaceutical compounds at mild and
practical protocols [29-31], herein we wish to report our
experimental results on the synthesis of azo-linked diindolyl
methanes using different synthesized substituted azo-linked
aldehydes and indole derivatives in the presence of (i) K10
(ii) L-proline and (iii) nano-Fe3O4 (Scheme 1).
As a preliminary test reaction, we studied the conversion
of a 2:1 ratio of indole and 2-hydroxy-5-(phenyldiazenyl)
benzaldehyde in the presence of (i) K10, (ii) L-proline and
(iii) nano-Fe3O4 as the catalyst at reflux condition. With the
catalyst in hand, we moved to study the effects of catalyst
amount on the model reaction and the results were listed in
(Table 1). No product was obtained in the absence of the
catalyst (Entry 1) indicating that the catalyst is necessary for
the reaction. 0.1g of K10, 15mol% of L-proline or 0.05 g
nano-Fe3O4 is sufficient to push the reaction forward but
lower amount of catalyst was not enough. Higher amount of
catalyst did not lead to significant change in the reaction
yield.
Fibromyalgia [9]. Thus indole and its derivatives have
been a topic for the preparation of research interest. Several
synthetic methods for the preparation of DIMs have been
reported by using catalysts such as lanthanide triflate [10],
FeCl3 [11], HOAc [12], molecular iodine [13], indium
trichloride and triflate [14], trifluoroacetic acid [15],
aluminum chloride [16] , ion exchange resin [17], lithium
perchlorate [18], copper (II) bromide [19], molibdato-
phosphoric acid [20], scandium (III) trifluoromethanesul-
fonate [21], zirconium (IV) chloride [22], bentonite [23],
lewis acids in ionic liquids [24], silica supported sodium
hydrogen sulphate and amberlyst-15 [25], trichloro-1,3,5-
triazine [26], sodium dodecyl sulfate(SDS) [27] and NBS
[28]. Most of these methods suffer various disadvantages
such as long reaction time, use of expensive lewis acids,
harsh reaction condition, and excess of toxic or organic
To optimize the reaction condition, this reaction was
carried out under ultrasound irradiation that lead to shorter
reaction time and higher yield. Furthermore, this protocol
has advantages such as reduced pollution, low cost,
simplicity in process and handling. This process is green,
environmental friendly, clean and fast and could be carried
out easily at mild temperature without undesirable side
reactions.
*Address correspondence to this author at the Department of Chemistry,
Rasht Branch, Islamic Azad University, Rasht, Iran; Tel: +981314222154;
Fax: +981314222152-4; E-mail: nikpassand@iaurasht.ac.ir
1875-6255/12 $58.00+.00
© 2012 Bentham Science Publishers

376 Letters in Organic Chemistry, 2012, Vol. 9, No. 5
Nikpassand et al.
R6
R6
R4
N
R1
R2
CHO
OH
(i) K10
(ii) L-proline
(iii) nano-Fe3O4
R6
+
R5
R1
R2
R5
N
R3
N
N
R4
N
R4
R5
OH
R3
N
N
1
2
3a-k
Scheme 1. Synthesis of azo-linked diindolylmethanes using K10, L-proline and nano-Fe3O4.
Table 1. The Effect of Amount of Catalyst when Synthesizing 3a at Refluxing Temperature
entry
catalyst
Catalyst amount
Time
Yield(%)a
1
2
-
-
18h
9h
No reaction
K10
0.01g
0.05g
0.1g
50
54
60
61
38
41
43
42
76
81
89
83
3
K10
8h
4
K10
7h
5
K10
0.2g
7h
6
L-proline
L-proline
L-proline
L-proline
nano-Fe3O4
nano-Fe3O4
nano-Fe3O4
nano-Fe3O4
5mol%
10mol%
15mol%
20mol%
0.01g
0.03g
0.05g
0.1g
12h
10h
9h
7
8
9
9h
10
11
12
13
30min
20min
15min
14min
aisolated yield.
With the optimal condition in hand, a series of azo-linked
aldehydes with either electron-donating or electron-
withdrawing groups attached to aromatic ring were
investigated. The results are summarized in (Table 2).
Satisfactory results in the synthesis of new generation of
diindolylmethanes were obtained when we used nano-Fe3O4
as the catalyst. It seems that the aldehydes having electron
withdrawing substituent react better than the aldehydes
having electron releasing substituent.
Following these results, we further investigated the
potential of nano-Fe3O4 for the selective synthesis of azo-
linked diindolylethanes of different types of azo-linked
O2N
N
N
OH
CHO
O2N
N
N
N
OH
+
(1mmol)
H
N
nano-Fe3O4
US, 5min
H
98% us
N
H
2mmol
H3C
N
N
OH
CHO
Me
N
N
OH
(1mmol)
N
H
N
H
0%
Scheme 2.

Comparative Study for the Aqeous Synthesis of New Generation
Letters in Organic Chemistry, 2012, Vol. 9, No. 5
377
aldehydes. The results showed that nano-Fe3O4 is able to
discriminate between aromatic compounds containing
electron donating and electron withdrawing groups, a
transformation that is difficult to accomplish via
conventional methods (Scheme 2).
General Procedure for the Synthesis of Compounds 3a-k
in the Presence of K10
A mixture of aldehyde (1 mmol), indole derivatives (2
mmol) and catalytic amount of K10 (0.1g) in H2O (10mL)
were placed into Pyrex glass open vessel and irradiated in a
water bath under silent condition by ultrasound (45 kHz) at
60˚C for the required reaction times (Table 2). After required
reaction time, the mixture was filtered to separate the
mixture of the catalyst and the product and the product was
washed with EtOH to separate of K10. EtOH was evaporated
under vacuum to afford 3a-k as crystalline product.
The structures of the synthesized compounds were
elucidated by IR, NMR and elemental analysis results. In the
1HNMR spectra of azo-linked diindolylmethanes, benzilic C-
H proton resonated at 6.1-6.2 ppm and in the 13CNMR
spectra of azo-linked diindolylmethanes, benzilic C-H
carbon resonated at 32 ppm.
Apart from the mild conditions of the process and its
excellent results, the simplicity of product isolation and the
possibility to recycle the catalyst offer a significant
advantage. Because nano-Fe3O4 is separated in the presence
of an efficient magnetic bar after the reaction is completed.
Our experiments indicated that nano-Fe3O4 was reusable.
Reusability of catalysts is shown in Fig. (1).
General Procedure for the Synthesis of Compounds 3a-k
in the Presence of L-Proline
A mixture of aldehyde (1 mmol), indole derivatives (2
mmol) and catalytic amount of L-proline in H2O (10mL)
were placed into Pyrex glass open vessel and irradiated in a
water bath under silent condition by ultrasound (45 kHz) at
60˚C for the required reaction times (Table 2). After required
reaction time, the mixture was filtered to afford 3a-k as
crystalline product.
General Procedure for the Synthesis of Compounds 3a-k
in the Presence of Nano-Fe3O4
A mixture of aldehyde (1 mmol), indole derivatives (2
mmol) and catalytic amount of nano-Fe3O4 in H2O (10mL)
were placed into Pyrex glass open vessel and irradiated in a
water bath under silent condition by ultrasound (45 kHz) at
60˚C for the required reaction times (Table 2). After required
reaction time, the mixture was filtered in the presence of an
efficient magnetic bar to separate the product 3a-k as
crystalline product.
Fig. (1). Reusability of nano-Fe3O4 under ultrasound irradiation.
2-(Di(1H-indol-3-yl)methyl)-4-(phenyldiazenyl)phenol
CONCLUSION
1
3a: M.p 263 °C, as a light-orange solid. HNMR (500
Finally, we develop an efficient, green, fast and
convenient procedure for the synthesis of azo-linked
diindolylmethanes through electrophilic substitution of azo-
linked aldehydes and indole derivatives over nano-Fe3O4.
This procedures offer advantages such as reduced reaction
time, mild reaction condition, productivity and higher yield,
ease of execution and economic viability of the catalyst. To
the best of our knowledge, the process described herein
represents the first example of synthesis of azo-linked
diindolylmethanes.
MHz, DMSO-d6, ppm): δ 6.26 (s, 1H), 6.80 (d, J = 1.5 Hz,
2H), 6.86 (t, J = 7.4 Hz, 2H), 7.01-7.07 (m, 3H), 7.30 (d, J =
8.0 Hz, 2H), 7.34 ( d, J = 8.1 Hz, 2H), 7.38 (d, J = 7.1 Hz,
1H), 7.44 (t, J = 7.7 Hz, 2H), 7.63 (d, J = 2.3 Hz, 1H), 7.65-
7.70 (m, 3H), 10.4 (s, 1H), 10.78 (s, 2H). 13CNMR (125
MHz, DMSO-d6, ppm): δ 32.58 (benzilic CH), 112.40,
116.61, 118.39, 119.11, 119.76, 121.76, 121.81, 122.92,
124.56, 126.77, 127.66, 130.07, 131.12, 132.88, 137.57,
145.98, 152.96, 159.07. Anal. Calcd. for C29H22N4O: C,
78.71; H, 5.01; N, 12.66. Found: C, 78.13; H, 5.25; N, 12.39.
2-(Bis(2-methyl-1H-indol-3-yl)methyl)-4-(phenyldiazenyl)
phenol
EXPERIMENTAL
1
3b: M.p 265 °C, as a light-orange solid. HNMR (500
Materials and Instruments
MHz, DMSO-d6, ppm): δ 2.4 (s, 3H), 2.5 (s, 3H), 6.2 (s, 1H),
6.87-6.89 (m, 4H), 7.03 (t, J = 7.5 Hz, 2H), 7.10 (d, J = 8.6
Hz, 1H), 7.32 (d, J = 7.8 Hz, 2H), 7.36 (d, J = 8.0 Hz, 2H),
7.54 (d, J = 8.8 Hz, 1H), 7.72 (d, J = 6.8 Hz, 1H), 7.81 (s,
1H), 8.03 (d, J = 7.4 Hz, 1H), 8.2 (s, 1H), 10.7 (s, 1H), 10.8
(s, 2H). 13CNMR (125 MHz, DMSO-d6, ppm): δ 12.79
(CH3), 33.75 (benzilic CH), 111.23, 112.40, 116.44, 118.86,
119.00, 120.38, 120.99, 122.88, 128.42, 129.50, 130.10,
131.11, 132.39, 132.78, 135.89, 145.88, 152.87, 159.82.
Anal. Calcd. for C31H26N4O: C, 79.12; H, 5.57; N, 11.91.
Found: C, 79.43; H, 5.63; N, 11.67.
Melting points were measured on an Electrothermal 9100
apparatus. IR spectra were determined on a Shimadzo IR-
470 spectrometer. 1H NMR spectra were recorded on a
Bruker DRX-500 and those of 13C NMR spectra on a Bruker
DRX 125 Avance spectrometer in DMSO-d6 as solvent and
with TMS as internal standard. Chemicals were purchased
from Merck and Fluka. Elemental analyses were done on a
Carlo-Erba EA1110CNNO-S analyzer and agreed with the
calculated values. All solvents used were dried and distilled
according to standard procedures.

378 Letters in Organic Chemistry, 2012, Vol. 9, No. 5
Nikpassand et al.
Table 2. Synthesis of Azo-Linked Diindolylmethanes Derivatives 3a-k Using K10, L-Proline and Nano-Fe3O4 under Ultrasound
Irradiation
L-proline
K10
nano-Fe3O4
Entry
Product
Yield
(%)
Yield
(%)
Time (min)
Yield (%)
Time(min)
Time(min)
N
N
OH
3a
150
45
80
85
7
94
NH
N
H
N
N
OH
3b
3c
3d
3e
160
55
77
63
52
120
78
7
5
6
5
92
98
96
97
NH
CH3
N
H
CH3
O2N
N
N
OH
120
120
50
40
50
5
95
94
91
N
H
N
H
O2N
N
N
OH
N
H
H3C
N
CH3
H
O2N
N
N
OH
Br
Br
N
H
N
H
H3C
N
N
OH
3f
120
65
110
84.5
8
95
N
H
N
H

Comparative Study for the Aqeous Synthesis of New Generation
Letters in Organic Chemistry, 2012, Vol. 9, No. 5
379
(Table 2). Contd…..
nano-Fe3O4
L-proline
K10
Entry
Product
Yield
(%)
Time (min)
Yield (%)
Time(min)
Time(min) Yield (%)
H3C
N
N
OH
OH
OH
Br
3g
150
180
140
40
120
70
92
92
8
6
7
92
99
96
Br
N
H
N
H
Br
N
N
3h
60
70
N
H
N
H
Br
N
N
Br
3i
42
70
Br
N
H
N
H
CH3
N
O2N
N
OH
3j
160
63
120
87
6
94
N
H
N
H
CH3
N
O2N
N
OH
Br
3k
180
45
5
91
5
95
Br
N
H
N
H
aisolated yield.
2-(Di(1H-indol-3-yl)methyl)-4-((4-nitrophenyl)diazenyl)
phenol
118.15, 119.12, 121.81, 122.84, 123.84, 124.58, 125.75,
127.50, 127.57, 133.26, 137.53, 146.14, 148.44, 156.41,
160.54. Anal. Calcd. for C29H21N5O3: C, 71.45; H, 4.34; N,
14.37. Found: C, 71.41; H, 4.78; N, 14.97.
3c: M.p >320 °C, as an orange solid. 1HNMR (500 MHz,
DMSO-d6, ppm): δ 6.2 (s, 1H), 6.81 (d, J = 1.7 Hz, 2H), 6.88
(t, J = 7.2 Hz, 2H), 7.04 (t, J = 7.3 Hz, 2H), 7.10 (d, J = 8.5
Hz, 1H), 7.29 (d, J = 7.9 Hz, 2H), 7.35 (d, J = 8.1 Hz, 2H),
7.72-7.76 (m, 2H), 7.88 (d, J = 8.9 Hz, 2H), 8.31 (d, J = 8.9
Hz, 2H), 10.7 (s, 1H), 10.8 (s, 2H). 13CNMR (125 MHz,
DMSO-d6, ppm): δ 32.54 (benzilic CH), 112.40, 116.85,
2-(Bis(2-methyl-1H-indol-3-yl)methyl)-4-((4-nitrophenyl)
diazenyl)phenol
3d: M.p >320 °C, as a dark-red solid. 1HNMR (500
MHz, DMSO-d6, ppm): δ 2.05 (s, 6H), 6.08 (s, 1H), 6.65 (t, J

380 Letters in Organic Chemistry, 2012, Vol. 9, No. 5
Nikpassand et al.
= 7.5 Hz, 2H), 6.82-6.87 (m, 4H), 6.9 (d, J = 8.6 Hz, 1H),
7.18 (d, J = 8.0 Hz, 2H), 7.72 (t, J = 6.8 Hz, 2H), 7.80 (d, J =
8.8 Hz, 2H), 8.27 (d, J = 8.8 Hz, 2H), 10.4 (s, 1H), 10.7 (s,
2H). 13CNMR (125 MHz, DMSO-d6, ppm): δ 12.10 (CH3),
33.76 (benzilic CH), 111.25, 112.14, 116.72, 118.90, 120.40,
121.90, 125.78, 129.32, 129.42, 132.78, 132.83, 135.87,
146.06, 156.33, 161.30. Anal. Calcd. for C31H25N5O3: C,
72.22; H, 4.89; N, 13.58. Found: C, 72.81; H, 4.53; N, 13.61.
C29H21BrN4O: C, 66.80; H, 4.06; N, 10.75. Found: C, 66.34;
H, 4.08; N, 10.76.
2-(Bis(5-bromo-1H-indol-3-yl)methyl)-4-((4-bromophenyl)
diazenyl)phenol
1
3i: M.p 263 °C, as a light-orange solid. HNMR (500
MHz, DMSO-d6, ppm): δ 6.2 (s, 1H), 6.93 (d, J = 1.3 Hz,
2H), 7.10 (d, J = 8.5 Hz, 1H), 7.17 (dd, J = 1.5 Hz, J = 8.6
Hz, 2H), 7.36 (d, J = 8.6 Hz, 2H), 7.44 (d, J = 1.1 Hz, 2H),
7.65 (s, 4H), 7.67 (d, J = 2.0 Hz, 1H), 7.70 (dd, J = 2.2 Hz, J
= 8.5 Hz, 1H), 10.6 (s, 1H), 11.0 (s, 2H). 13CNMR (125
MHz, DMSO-d6, ppm): δ 32.30 (benzilic CH), 111.85,
114.58, 116.84, 117.72, 121.82, 122.61, 124.40, 124.85,
126.30, 126.37, 129.34, 132.31, 133.12, 136.25, 145.92,
151.82, 159.30. Anal. Calcd. for C29H19Br3N4O: C, 51.28; H,
2.82; N, 8.25. Found: C, 51.74; H, 2.43; N, 8.13.
2-(Bis(5-bromo-1H-indol-3-yl)methyl)-4-((4-nitrophenyl)
diazenyl)phenol
1
3e: M.p >320 °C, as a, light-red solid. HNMR (500
MHz, DMSO-d6, ppm): δ 6.18 (s, 1H), 6.92 (d, J = 2.0 Hz,
2H), 7.11 (d, J = 8.6 Hz, 1H), 7.16 (dd, J = 1.8 Hz, J = 8.6
Hz, 2H), 7.35 (d, J = 8.5 Hz, 2H), 7.42 (d, J = 1.4 Hz, 2H),
7.70 (d, J = 2.3Hz, 1H), 7.76 (dd, J = 2.4Hz, J = 8.6Hz, 1H),
7.89 (d, J = 8.9 Hz, 2H), 8.31 (d, J = 8.9 Hz, 2H,), 10.82 (s,
1H), 11.08 (s, 2H). 13CNMR (125 MHz, DMSO-d6, ppm): δ
32.27 (benzilic CH), 111.84, 114.59, 117.00, 117.56, 121.76,
123.38, 123.85, 124.39, 125.76, 126.32, 126.96, 129.29,
132.58, 136.24, 146.18, 148.50, 156.37, 160.38. Anal. Calcd.
for C29H19Br2N5O3: C, 53.98; H, 2.97; N, 10.85. Found: C,
53.82; H, 2.81; N, 10.21.
2-(Di(1H-indol-3-yl)methyl)-4-((2-methyl-4-nitrophenyl)
diazenyl)phenol
1
3j: M.p >320 °C, as a red solid. HNMR (500 MHz,
DMSO-d6, ppm): δ 2.5 (s, 3H), 6.25 (s, 1H), 6.87 (s, 2H),
6.88 (d, J = 8.6 Hz, 2H), 7.04 (t, J = 7.5 Hz, 2H), 7.10 (d, J =
8.6 Hz, 1H), 7.32 (d, J = 7.8Hz, 2H), 7.36 (d, J = 8.04 Hz,
2H), 7.54 (d, J = 8.8 Hz, 1H), 7.72 (d, J = 6.8 Hz, 1H),
7.81(s, 1H), 8.03 (d, J = 7.4 Hz, 1H ), 8.2 (s, 1H), 10.7 (s,
1H), 10.8 (s, 2H). 13CNMR (125 MHz, DMSO-d6, ppm): δ
17.70 (CH3), 32.81(benzilic CH), 112.38, 116.80, 117.31,
118.19, 119.61, 119.77, 121.77, 122.65, 122.89, 124.52,
126.95, 127.64, 127.75, 133.20, 137.57, 138.68, 146.68,
148.23, 154.47, 160.35. Anal. Calcd. for C30H23N5O3: C,
71.84; H, 4.62; N, 13.96. Found: C, 71.41; H, 4.55; N, 13.41.
2-(Di(1H-indol-3-yl)methyl)-4-(p-tolyldiazenyl)phenol
3f: M.p >320 °C, as a dark-red solid. 1HNMR (500 MHz,
DMSO-d6, ppm): δ 2.3 (s, 3H), 6.24 (s, 1H), 6.79 (s, br, 2H),
6.8 (s, br, 2H), 7.03 (s, br, 3H), 7.28 (t, J = 8.0 Hz, 4H), 7.35
(d, J = 7.4Hz, 3H), 7.60 (d, J = 6.3Hz, 3H), 10.36 (s, 1H),
10.79 (s, 2H). 13CNMR (125 MHz, DMSO-d6, ppm): δ 21.76
(CH3), 32.51(benzilic CH), 112.37, 116.55, 118.37, 119.06,
119.72, 121.48, 121.76, 122.91, 124.52, 126.02, 127.62,
130.59, 134.91, 137.52, 141.12, 145.90, 152.37, 158.76.
Anal. Calcd. for C30H24N4O: C, 78.92; H, 5.30; N, 12.27.
Found: C: 78.25; H, 5.81; N, 12.61.
2-(Bis(5-bromo-1H-indol-3-yl)methyl)-4-((2-methyl-4-
nitrophenyl)diazenyl)phenol
3k: M.p 259°C, as a dark-red- solid. 1HNMR (500 MHz,
DMSO-d6, ppm): δ 2.5 (s, 3H), 6.1 (s, 1H), 6.99 (s, 2H), 7.11
(d, J = 8.1 Hz, 1H), 7.16 (d, J = 7.6 Hz, 2H), 7.36 (d, J = 8.2
Hz, 2H), 7.44 (s, 2H), 7.53 (d, J = 8.4 Hz, 1H), 7.72-7.76 (m,
2H), 8.02 (d, J = 7.7 Hz, 1H), 8.2 (s, 1H), 10.7 (s, 1H), 11.10
(s, 2H). Anal. Calcd. for C30H21Br2N5O3: C, 54.65; H, 3.21;
N, 10.62. Found: C, 54.63; H, 3.71; N, 10.42. 4; H, 4.46; N,
22.14. Found: C, 68.62; H, 4.55; N, 22.07.
2-(bis(5-bromo-1H-indol-3-yl)methyl)-4-(p-tolyldiazenyl)
phenol
1
3g: M.p 258 °C, as an orange solid. HNMR (500 MHz,
DMSO-d6, ppm): δ 2.3 (s, 3H), 6.2 (s, 1H), 6.9 (s, 2H), 7.08
(d, J = 7.8 Hz, 1H ), 7.17 (d, J = 7.4 Hz, 2H), 7.27 (d, J = 6.5
Hz, 2H), 7.36 (d, J = 8.0 Hz, 2H), 7.43 (s, 2H), 7.61-7.67 (m,
4H), 10.4 (s, 1H), 11.08 (s, 2H). 13CNMR (125 MHz,
DMSO-d6, ppm): δ 21.78 (CH3), 32.29 (benzilic CH),
111.83, 114.57, 116.72, 117.79, 121.82, 122.13, 122.95,
124.37, 126.01, 126.27, 129.36, 130.60, 132.12, 136.25,
141.23, 146.01, 150.95, 158.62. Anal. Calcd. for
C30H22Br2N4O: C, 58.65; H, 3.61; N, 9.12. Found: C, 58.71;
H, 3.32; N, 9.06.
CONFLICT OF INTEREST
Declared none.
ACKNOWLEDGEMENT
We thank the Research Committee of Islamic Azad
University of Rasht Branch for partial support given to this
study.
4-((4-Bromophenyl)diazenyl)-2-(di(1H-indol-3-yl)methyl)
phenol
1
3h: M.p 263 °C, as a light-orange solid. HNMR (500
MHz, DMSO-d6, ppm): δ 6.2 (s, 1H), 6.79 (d, J = 1.8 Hz,
2H), 6.87 (t, J = 7.2 Hz, 2H), 7.05 (dd, J =7.3Hz, J = 14.0
Hz, 4H), 7.28 (d, J = 8.0 Hz, 2H), 7.35 (d, J = 8.1 Hz, 2H),
7.38 (d, J = 8.1 Hz, 2H), 7.62-7.80 (m, 3H), 10.4 (s, 1H),
10.78 (s, 2H). 13CNMR (125 MHz, DMSO-d6, ppm): δ 32.52
(benzilic CH), 112.37, 116.65, 118.27, 119.08, 119.69,
121.77, 122.02, 124.54, 124.84, 126.88, 127.59, 132.97,
133.11, 137.52, 151.84, 154.18, 159.16. Anal. Calcd. for
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