Efficient RuIII-catalyzed condensation of indoles and aldehydes or ketones

Article abstract of DOI:10.1139/V06-159

Synthesis of bis(indolyl)methanes through condensation of indoles and various aldehydes or ketones, using Ru^III as catalyst, is reported. It was found that the catalytic system involving Ru^III affords the products smoothly under very

Full text of DOI:10.1139/V06-159

1
541
III
Efficient Ru -catalyzed condensation of indoles
and aldehydes or ketones
Khalil Tabatabaeian, Manouchehr Mamaghani, Nosratollah Mahmoodi, and
Alireza Khorshidi
Abstract: Synthesis of bis(indolyl)methanes through condensation of indoles and various aldehydes or ketones, using
III
III
Ru as catalyst, is reported. It was found that the catalytic system involving Ru affords the products smoothly under
very mild conditions in good to high yields.
Key words: aldehydes, ketones, bis(indolyl)methanes, indoles, ruthenium.
Résumé : Utilisant du Ru(III) comme catalyseur, on a réalisé la synthèse de bis(indolyl)méthanes par le biais de la
condensation d’indoles et de divers aldéhydes ou cétones. On a trouvé que le système catalytique impliquant du
Ru(III) permet d’obtenir facilement les produits dans des conditions douces et avec des rendements allant de bon à éle-
vés.
Mots clés : aldéhydes, cétones, bis(indolyl)méthanes, indoles, ruthénium.
[
Traduit par la Rédaction] Tabatabaeian et al. 1545
Introduction
We found that Ruthenium (III) chloride hydrate is a very ef-
fective catalyst for the double addition of indoles to alde-
hydes or ketones, yielding bis(indolyl) derivatives in high
yields. The ruthenium catalyst was used in low concentra-
tions (as low as 1.2 mol%) and a relatively easy work-up af-
fords catalytic formation of a carbon–carbon bond under
mild reaction conditions. To the best of our knowledge, this
Transition metal-catalyzed C–H bond activation has re-
ceived considerable attention in synthetic organic chemistry
since the cleavage of an unreactive C–H bond and subse-
quent addition of the C–H unit into unsaturated substrates
could lead to the formation of a new C–C bond (1). The for-
mation of a C–C bond is one of the most fundamental pro-
jects in organic chemistry. Much effort has naturally been
devoted to developing more convenient and efficient strate-
gies for the formation of C–C bonds. During the last two de-
cades, many successful applications of catalytic C–H bond
activation directed toward the construction of C–C bonds
have been reported in synthetic communities (2).
III
is the first report on the use of Ru salts as catalyst for the
condensation of indoles with various aldehydes or ketones.
Results and discussion
Typical results of the ruthenium-catalyzed condensation of
indoles and aldehydes or ketones are shown in Tables 1 and
The development of new efficient synthetic methods lead-
ing to indole derivatives continues to receive much attention
in organic synthesis because of their biological activities (3).
Various indole derivatives occur in many pharmacologically
and biologically active compounds (4). Among of them,
bis(indolyl)methanes possess a wide range of biological ac-
tivity and their synthesis has received a considerable amount
of interest (5, 6). Generally, bis(indolyl)methanes are pre-
pared by the condensation of indoles with various aldehydes
or ketones in the presence of either protic (7) or Lewis acids
2
and they indicate the scope of the reaction. Treatment of
benzaldehyde (1.2 mmol) with indole (2 mmol) in the
presence of RuCl ·nH O catalyst (1.2 mol%) in methanol
3
2
(
2 mL) at RT for 27 min gave the corresponding 3,3′-
bis(indolyl)phenylmethane in 92% yield (product 1a). No at-
tempts were made to characterize byproducts since they are
formed in trace amounts (using GLC analysis). The reaction
can be used for substituted aromatic aldehydes with either
electron-donating or electron-withdrawing groups (Table 1,
entries b–e). Furthermore, the reaction of indole with aliphatic
aldehydes furnished high yields of the corresponding prod-
uct class (Table 1, entries f and g).
8–10). On the other hand, RuIII salts are well-known to cat-
(
alyze many organic transformations, including aldol and
Michael reactions (11), oxidation reactions of alkanes (12),
oxidative cyanation of amines (13), and many others (14).
Encouraged by these results, we studied the condensation
reaction between indole and some ketones. The method is
highly chemoselective, as ketones do not participate in the
reaction in ambient conditions. This selectivity might be
useful in the reaction of multifunctional carbonyl com-
pounds with indole since they have both aldehyde and
ketone functionalities. However, the method is still effective
enough to afford the condensation products of indole and ke-
tones through reflux of the reaction mixture (Table 1, entries
h–l) in good yields.
Received 12 July 2006. Accepted 2 October 2006. Published
on the NRC Research Press Web site at http://canjchem.nrc.ca
on 17 November 2006.
1
K. Tabatabaeian, M. Mamaghani, N. Mahmoodi, and
A. Khorshidi. Department of Chemistry, Faculty of Sciences,
The University of Guilan, P. O. Box 41335–1914, Iran.
1Corresponding author (email: Taba@guilan.ac.ir).
Can. J. Chem. 84: 1541–1545 (2006)
doi:10.1139/V06-159
© 2006 NRC Canada

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Can. J. Chem. Vol. 84, 2006
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Table 1. Ru -catalyzed condensation of indole and aldehydes or ketones.
R
R'
O
RuIII (1.2 mol%)
+
CH OH, RT
3
N
H
R
R'
HN
NH
Entry
R
R′
Product
Time (min)
27
Yield (%)a
92c
a
b
c
d
e
f
C H
H
1a
1b
1c
1d
1e
1f
6
5
i
4-pr -C H
H
25
93
6
4
4-OHC H4
H
30
82d
88c
85e
73
6
2-ClC H4
H
30
6
3-NO C H
4
H
30
2
6
CH3
H
30
g
h
i
CH (CH )
H
1g
1h
1i
30
87
3
2 3
C H
CH3
CH3
CH3
CH3
180b
60b
68d
6
5
4-CH OC H
4
72
3
6
j
3,4-(CH O) C H
1j
120b
120b
180b
77
3
2
6
3
k
l
4-NO C H
4
1k
1l
73
2
6
C H
C H
51
6
5
6
5
1
13
Note: All products were characterized by H NMR, C NMR, and IR data.
a
Isolated yields.
Reflux.
b
cde
Identified by comparison with authentic samples (15, 16, 8).
With regard to the indole moiety, the present protocol is
reaction solvent, methanol has lower toxicity in contrast to
noteworthy because substituted indoles underwent smooth
reactions with aromatic aldehydes giving excellent yields of
products (Table 2). For example, treatment of 1-, 2-, and 5-
substituted indoles with various aromatic aldehydes gave
corresponding products 2a–2f, most of them insoluble in the
reaction media (solvent methanol) and this makes the work-
up even easier (see Experimental section). Also, the reaction
times for 1- and 2-substituted indoles are much less than
those of unsubstituted substrates.
CH CN (8–10). In the reaction of substituted indoles with
3
aromatic aldehydes, the products are mainly insoluble in
methanol, therefore simple filtration of the reaction mixture
and rinsing with methanol provides completely pure prod-
ucts. The unique feature of the reaction is selectivity be-
tween ketones and aldehydes at ambient temperature while
the other methods catalyze the reaction of both aldehydes
and ketones at room temperature (8–10) or only catalyze the
reaction of aldehydes (15). Further manipulation of this re-
action is underway.
The reaction of indole and benzaldehyde was taken as a
representative example and the progress of the reaction was
monitored by GLC technique. To examine the influence of
the catalyst concentration, we also carried out the reaction of
benzaldehyde and indole in different catalyst concentrations.
Due to the decomposition of the products under chromato-
graphic conditions, decrease in the corresponding aldehyde
peak areas was selected as a measure of reaction coordinate.
Also, the peak of methanol was used as internal standard.
The results are summarized in Table 3.
Experimental
General
IR spectra were recorded on a Shimadzu FTIR-8400S
1
spectrometer. H NMR spectra were obtained on a Bruker
1
3
DRX-500 Avance and C NMR spectra were obtained on a
1
13
III
Bruker DRX-125 Avance. Chemical shifts of H and
C
These results reveal that the Ru system is at least four
NMR spectra were expressed in parts per million downfield
from tetramethylsilane. Analytical GLC evaluations of prod-
uct mixtures were carried out on a Varian CP-3800 chro-
matograph (using a split/splitless injector, CP Sil 8CB
column, FID assembly). Melting points were measured on a
BÜCHI Melting Point B-540 and are uncorrected. Elemental
analyses were made with a Carlo-Erba EA1110 CNNO-S
analyzer and agreed with the calculated values.
times more effective than the previously reported catalytic
III
system using Fe in ionic liquids (15) in terms of utilized
catalyst concentration (1.2% vs. 5%). Also, the catalytic ac-
tivity is nearly ten times greater in terms of reaction time
3 min vs. 30 min in -5 mol% of catalyst).
(
Conclusion
In brief, we have developed a convenient method for the
synthesis of bis(indolyl)methanes using the condensation re-
action of indoles and aldehydes or ketones in the presence of
RuCl ·nH O as efficient catalyst. With regard to the previous
Materials
HPLC grade methanol was used as solvent and all other
materials were purchased from Merck and used without fur-
ther purification.
3
2
works, the present protocol has several advantages. As the
©
2006 NRC Canada

Tabatabaeian et al.
1543
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Table 2. Ru -catalyzed condensation of substituted indoles and aldehydes.
X
R3
R3
CHO
R3
RuIII (1.2 mol%)
R2
+
3
CH OH, RT
N
H
X
N
N
R1
R2
R2
R1
R1
Entry
R1
R2
R3
X
Product
Time (min)
Yield (%)a
a
b
c
d
e
f
CH3
CH3
CH3
H
H
H
H
H
H
H
Br
H
2a
2b
2c
2d
2e
2f
5
3
98
98
95
98b
96
75
i
H
4-pr -C H
6 4
H
3-(CH O)-4-(HO)C H
3
10
3
3
6
CH3
CH3
H
H
i
H
4-pr -C H
10
30
6
4
H
H
1
13
Note: All products were characterized by H NMR, C NMR, and IR data.
a
Isolated yields.
Identified by comparison with authentic samples (17).
b
Table 3. RuCl ·nH O-catalyzed condensation of benzaldehyde
and indole in different catalyst concentrations.
1H, Ar-CH), 6.7 (s, 2H), 7.06 (t, J = 7.5 Hz, 2H), 7.18 (d,
J = 8.00 Hz, 2H), 7.21 (t, J = 7.5 Hz, 2H), 7.3 (d, J =
3
2
7
2
2
1
1
.3 Hz, 2H), 7.39 (d, J = 8.00 Hz, 2H), 7.46 (d, J = 7.9 Hz,
H), 7.91 (br, s, 2H, NH). C NMR (125 MHz, CDCl3,
Reaction
Aldehyde
Catalyst concentration
(mol% Ru/aldehyde)
13
Entry time (min) consumption (%)
5 °C, ppm) δ: 24.51, 34.11, 40.2, 111.46, 119.6, 120.42,
20.44, 122.3, 124.0, 126.66, 127.6, 128.98, 137.12, 141.7,
46.92. Anal. calcd. for C H N : C 85.68, H 6.64, N 7.69;
1
2
3
4
5
6
7
8
9
1
27
3
15
27
3
15
27
3
15
27
98
1.2
1.9
1.9
1.9
3.8
3.8
3.8
5.6
5.6
5.6
91.6
97.8
97.8
96.7
97.2
97.6
98
2
6
24
2
found: C 85.74, H 6.67, N 7.65.
3
,3′-Bis(indolyl)methylmethane (1f)
Solid, mp 157–159 °C. IR (KBr, cm ) υ: 424, 499, 578,
–
1
740, 756, 815, 1018, 1097, 1220, 1334, 1421, 1456, 2837,
2925, 2956, 3417 (NH). H NMR (500 MHz, CDCl , 25 °C,
ppm) δ: 1.87 (d, J = 7.06 Hz, 3H), 4.74 (q, J = 6.96 Hz, 1H),
6
1
98.3
98.3
3
0
.96 (d, J= 2.06 Hz, 2H), 7.10 (t, J = 7.53 Hz, 2H), 7.23 (t,
J = 7.30 Hz, 2H), 7.39 (d, J = 8.15 Hz, 2H), 7.64 (d, J =
7.92 Hz, 2H), 7.89 (br, s, 2H, NH). C NMR (125 MHz,
1
3
Ruthenium-catalyzed condensation of benzaldehyde and
indole
A 20 mL flask equipped with a magnetic stirring bar was
charged with methanol (2 mL), benzaldehyde (127.4 mg,
CDCl , 25 °C, ppm) δ: 22.17, 28.62, 111.50, 119.46, 120.18,
3
121.64, 122.13, 122.22, 127.36, 137.09. Anal. calcd. for
C H N : C 83.04, H 6.19, N 10.76; found: C 83.11, H
1
8
16
2
1
.2 mmol), and indole (234.4 mg, 2 mmol). RuCl ·nH O
6.24, N 10.78.
3
2
(
3 mg, 0.014 mmol) was added into the flask and the reac-
tion mixture was stirred at RT. After 0.5 h, the reaction
mixture was purified by preparative TLC (petroleum ether –
ethyl acetate, 10:4) providing a pure product (296 mg, 92%).
The same procedure was also used for the other products
listed in Tables 1 and 2. In the case of entries a–e in Table 2,
simple filtration of the reaction mixture and treatment with
methanol provided pure products.
3
,3′-Bis(indolyl)butylmethane (1g)
Viscous liquid. IR (KBr, cm ) υ: 424, 487, 582, 740,
–
1
800, 929, 1010, 1093, 1218, 1244, 1336, 1417, 1456, 2856,
2927, 2954, 3055, 3415 (NH). H NMR (500 MHz, CDCl ,
25 °C, ppm) δ: 0.97 (t, J = 6.95 Hz, 3H), 1.44–1.49 (m, 4H),
2.27–2.33 (m, 2H), 4.55 (t, J = 7.40 Hz, 1H), 6.98 (d, J =
1
3
2
.08 Hz, 2H), 7.14 (t, J = 7.43 Hz, 2H), 7.24 (t, J = 7.35 Hz,
3
,3-Bis(indolyl)-4-isopropylphenylmethane (1b)
2H), 7.36 (d, J = 8.12 Hz, 2H), 7.70 (d, J = 7.90 Hz, 2H),
–
1
13
Solid, mp 153 to 154 °C. IR (KBr, cm ) υ: 422, 468, 497,
7.84 (br, s, 2H, NH). C NMR (125 MHz, CDCl , 25 °C,
3
5
1
86, 599, 744, 752, 792, 1010, 1089, 1215, 1338, 1417,
456, 1510, 2867, 2962, 3051, 3421 (NH). H NMR
ppm) δ: 14.64, 23.33, 31.03, 34.42, 36.09, 111.59, 119.44,
120.14, 120.97, 121.93, 122.16, 127.63, 137.02. Anal. calcd.
for C H N : C 83.40, H 7.33, N 9.26; found: C 83.43, H
1
(
(
500 MHz, CDCl , 25 °C, ppm) δ: 1.29 (d, 6H, J = 7.00 Hz,
3
21 22
2
CH ) CH), 2.93 (sept, J = 7.00 Hz, -CH(CH ) ), 5.91 (s,
7.36, N 9.25.
3
2
3 2
©
2006 NRC Canada

1
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Can. J. Chem. Vol. 84, 2006
3
,3′-Bis(indolyl)methyl-4-methoxyphenylmethane (1i)
(500 MHz, CDCl , 25 °C, ppm) δ: 3.73 (s, 6H), 5.95 (s, 1H),
3
–
1
Solid, mp 225–227 °C. IR (KBr, cm ) υ: 428, 457, 588,
13, 742, 783, 823, 844, 1004, 1026, 1080, 1097, 1178,
244, 1290, 1336, 1369, 1411, 1456, 1508, 1604, 2831,
6.59 (s, 2H), 7.06 (t, J = 7.72 Hz, 2H), 7.21–7.28 (m, 3H),
7.31–7.37 (m, 4H), 7.41 (d, J = 5.32 Hz, 2H), 7.44 (d, J =
6
1
2
1
3
7.90 Hz, 2H). C NMR (125 MHz, CDCl , 25 °C, ppm) δ:
3
1
935, 2977, 3058, 3413 (NH). H NMR (500 MHz,
33.11, 40.52, 109.48, 118.70, 119.07, 120.48, 121.85,
126.45, 127.90, 128.63, 128.70, 129.13, 137.85, 144.89.
Anal. calcd. for C H N : C 85.68, H 6.33, N 7.99; found:
(
(
CD ) SO, 25 °C, ppm) δ: 2.05 (s, 3H), 3.52 (s, 3H), 6.42
3
2
d, J = 2.35 Hz, 2H), 6.50 (d, J = 8.76 Hz, 2H), 6.58 (t, J =
2
5
22
2
7
8
8
.82 Hz, 2H), 6.80 (t, J = 7.75 Hz, 2H), 7.00 (d, J =
.00 Hz, 2H), 7.05 (d, J = 8.76 Hz, 2H), 7.10 (d, J =
.12 Hz, 2H), 9.58 (br, s, 2H, NH). C NMR (125 MHz,
C 85.69, H 6.33, N 8.01.
1
3
3,3′-Bis(1-methyl-indolyl)-4-isopropylphenylmethane (2b)
–
1
(
1
1
CD ) SO, 25 °C, ppm) δ: 29.30, 43.19, 55.32, 111.67,
Solid, mp 147–149 °C. IR (KBr, cm ) υ: 426, 567, 595,
3
2
13.05, 118.36, 120.96, 121.94, 123.89, 124.22, 126.64,
29.28, 137.60, 140.97, 157.52. Anal. calcd. for C H N O:
676, 738, 767, 804, 860, 1010, 1105, 1153, 1222, 1261,
1326, 1369, 1421, 1465, 1510, 1548, 1612, 2871, 2925,
2
5
22
2
1
C 81.94, H 6.05, N 7.64; found: C 81.87, H 6.11, N 7.66.
2958, 3049. H NMR (500 MHz, CDCl , 25 °C, ppm) δ:
3
1
.30 (d, J = 6.90 Hz, 6H), 2.95 (sep, J = 6.90 Hz, 1H), 3.74
3
,3′-Bis(indolyl)methyl-3,4-dimethoxyphenylmethane (1j)
(s, 6H), 5.92 (s, 1H), 6.62 (s, 2H), 7.06 (t, J = 7.20 Hz, 2H),
7.18 (d, J = 7.90 Hz, 2H), 7.26 (t, J = 8.00 Hz, 2H), 7.31–
7.35 (m, 4H), 7.46 (d, J = 7.90 Hz, 2H). C NMR
–
1
Solid, mp 218–220 °C. IR (KBr, cm ) υ: 424, 478, 547,
80, 605, 655, 738, 746, 763, 783, 817, 873, 1004, 1022,
095, 1110, 1139, 1228, 1245, 1253, 1334, 1409, 1444,
1
3
5
1
1
(125 MHz, CDCl , 25 °C, ppm) δ: 24.50, 33.11, 34.09, 40.09,
3
1
460, 1506, 1593, 2839, 2933, 2960, 3355, 3413. H NMR
109.45, 118.97, 118.99, 120.54, 121.78, 126.63, 127.97,
128.61, 128.90, 137.84, 142.12, 146.76. Anal. calcd. for
C H N : C 85.67, H 7.19, N 7.14; found: C 85.70, H 7.20,
(
500 MHz, (CD ) SO, 25 °C, ppm) δ: 1.75 (s, 3H), 3.09 (s,
3
2
3
8
8
8
H), 3.29 (s, 3H), 6.17 (d, J = 2.40 Hz, 2H), 6.22 (d, J =
.48 Hz, 1H), 6.27 (t, J = 7.5 Hz, 2H), 6.35 (dd, J =
.50 Hz, J = 2.11 Hz, 1H), 6.44–6.50 (m, 3H), 6.69 (d, J =
.03 Hz, 2H), 6.81 (d, J = 8.11 Hz, 2H), 9.78 (br, s, 2H,
2
8
28
2
N 7.15.
3,3′-Bis(1-methyl-indolyl)-3-methoxy-4-hydroxyphenyl-
1
3
NH). C NMR (125 MHz, (CD ) SO, 25 °C, ppm) δ: 29.22,
methane (2c)
3
2
–
1
4
1
1
6
3.19, 55.69, 55.72, 110.51, 111.52, 112.39, 118.02, 120.32,
20.63, 121.57, 123.55, 123.59, 126.37, 137.35, 141.36,
46.72, 147.83. Anal. calcd. for C H N O : C 78.76, H
Solid, mp 147–149 °C. IR (KBr, cm ) υ: 426, 505, 690,
738, 779, 804, 869, 1010, 1026, 1116, 1199, 1220, 1251,
1267, 1326, 1369, 1427, 1508, 1612, 2935, 3490. H NMR
1
2
6
24
2
2
.10, N 7.07; found: C 78.81, H 6.11, N 7.10.
(500 MHz, CDCl , 25 °C, ppm) δ: 3.74 (s, 6H), 3.84 (s, 3H),
3
5
.56 (s, 1H), 5.88 (s, 1H), 6.59 (s, 2H), 6.86 (d, J = 8.14 Hz,
3
,3′-Bis(indolyl)methyl-4-nitrophenylmethane (1k)
1H), 6.89 (d, J = 8.14 Hz, 1H), 6.96 (s, 1H), 7.07 (t, J =
7.35 Hz, 2H), 7.27 (t, J = 7.21 Hz, 2H), 7.36 (d, J = 8.12 Hz,
–
1
Solid, mp 250 to 251 °C. IR (KBr, cm ) υ: 422, 457, 551,
1
3
5
1
82, 636, 700, 744, 770, 808, 862, 1008, 1107, 1245, 1338,
409, 1458, 1504, 1591, 2923, 2981, 3045, 3409 (NH). H
2H), 7.46 (d, J = 7.85 Hz, 2H). C NMR (125 MHz, CDCl3,
25 °C, ppm) δ: 33.13, 40.22, 56.35, 109.50, 111.86, 114.41,
118.94, 119.05, 120.51, 121.68, 121.84, 127.88, 128.68, 136.99,
137.85, 144.20, 146.75. Anal. calcd. for C H N O : C
1
NMR (500 MHz, (CD ) SO, 25 °C, ppm) δ: 2.04 (s, 3H),
3
2
6
.42 (d, J = 2.42 Hz, 2H), 6.54 (t, J = 7.60 Hz, 2H), 6.76 (t,
2
6
24
2
2
J = 7.60 Hz, 2H), 6.87 (d, J = 8.07 Hz, 2H), 7.07 (d, J =
78.76, H 6.10, N 7.07; found: C 78.81, H 6.15, N 7.10.
8
8
.17 Hz, 2H), 7.28 (d, J = 8.94 Hz, 2H), 7.75 (d, J =
.87 Hz, 2H), 9.98 (br, s, 2H, NH). C NMR (125 MHz,
1
3
3,3′-Bis(2-methyl-indolyl)-4-isopropylphenylmethane (2e)
–
1
(
CD ) SO, 25 °C, ppm) δ: 29.16, 44.25, 111.91, 118.64,
Solid, mp 224–226 °C. IR (KBr, cm ) υ: 451, 493, 582,
3
2
1
1
7
21.22, 121.37, 122.24, 123.02, 124.01, 126.16, 129.32,
37.59, 145.99, 156.70. Anal. calcd. for C H N O : C
599, 740, 784, 833, 1016, 1220, 1244, 1299, 1342, 1423,
1
1458, 1510, 2920, 2956, 3049, 3396 (NH), 3438. H NMR
2
4
19
3
2
5.57, H 5.02, N 11.02; found: C 75.52, H 5.05, N 11.06.
(500 MHz, (CD ) SO, 25 °C, ppm) δ: 0.94 (d, J = 6.90 Hz,
3
2
6
H), 1.78 (s, 6H), 2.59 (sep, J = 6.90 Hz, 1H), 5.63 (s, 1H),
3
,3′-Bis(indolyl)diphenylmethane (1l)
6.44 (t, J = 8.04 Hz, 2H), 6.62–6.65 (m, 4H), 6.77 (d, J =
8.12 Hz, 2H), 6.86 (d, J = 8.04 Hz, 2H), 6.93 (d, J =
8.05 Hz, 2H), 9.50 (br, s, 2H, NH). C NMR (125 MHz,
–
1
Solid. IR (KBr, cm ) υ: 426, 487, 580, 607, 624, 702,
1
3
7
1
42, 815, 1012, 1033, 1101, 1242, 1336, 1373, 1413, 1456,
485, 1606, 1720, 2850, 2920, 3053, 3407 (NH). H NMR
1
(CD ) SO, 25 °C, ppm) δ: 12.51, 24.36, 33.72, 38.93,
3
2
(
500 MHz, CDCl , 25 °C, ppm) δ: 6.80–6.85 (m, 4H), 6.87
d, J = 2.47 Hz, 2H), 7.10–7.15 (m, 3H), 7.20–7.27 (m, 5H),
110.44, 113.13, 118.36, 119.16, 119.96, 126.04, 128.99, 129.03,
132.41, 135.49, 141.68, 146.35. Anal. calcd. for C H N :
3
(
2
8
28
2
1
3
7
.34–7.37 (m, 6H), 7.95 (br, s, 2H, NH). C NMR
C 85.67, H 7.19, N 7.14; found: C 85.69, H 7.17, N 7.14.
(
1
1
125 MHz, CDCl , 25 °C, ppm) δ: 54.65, 111.61, 112.30,
3
19.48, 120.05, 121.96, 122.96, 126.39, 127.89, 128.16,
30.56, 137.26, 146.39. Anal. calcd. for C H N : C 87.41,
3,3′-Bis(5-bromo-indolyl)phenylmethane (2f)
–
1
Solid, mp 246–248 °C. IR (KBr, cm ) υ: 420, 487, 584,
2
9
22
2
H 5.56, N 7.03; found: C 87.44, H 5.60, N 6.99.
609, 659, 703, 732, 750, 771, 800, 858, 871, 881, 979, 1099,
1
1
217, 1334, 1417, 1442, 1460, 1560, 1596, 3417 (NH). H
3
,3′-Bis(1-methyl-indolyl)phenylmethane (2a)
NMR (500 MHz, (CD ) SO, 25 °C, ppm) δ: 5.14 (s, 1H),
3 2
–
1
Solid, mp 199–201 °C. IR (KBr, cm ) υ: 428, 518, 572,
6.11 (d, J = 1.94 Hz, 2H), 6.52 (dd, J = 8.57, J = 10.73 Hz,
2H), 6.59 (t, J = 7.00 Hz, 1H), 6.65–6.71 (m, 6H), 6.75 (d,
7
1
02, 742, 769, 800, 1010, 1118, 1130, 1150, 1199, 1224,
238, 1328, 1369, 1425, 1475, 2933, 3020, 3053. H NMR
1
13
J = 1.40 Hz, 2H), 10.13 (br, s, 2H, NH). C NMR
©
2006 NRC Canada

Tabatabaeian et al.
1545
(
125 MHz, (CD ) SO, 25 °C, ppm) δ: 39.75, 111.35, 113.31,
6. J.K. Porter, C.W. Bacon, J.D. Robins, D.S. Himmelsbach, and
3
2
1
1
5
17.72, 121.43, 123.68, 125.33, 126.19, 128.22, 128.39,
28.47, 135.56, 143.94. Anal. calcd. for C H Br N : C
H.C. Higman. J. Agric. Food Chem. 25, 88 (1977).
7
8
9
. M. Roomi and S. MacDonald. Can. J. Chem. 48, 139 (1970).
. R. Nagarajan and P.T. Perumal. Tetrahedron, 58, 1229 (2002).
. J.S. Yadav, B.V. Subba Reddy, C.V.S.R. Murthy, G.M. Kumar,
and C. Madan. Synthesis, 5, 783 (2001).
2
3
16
2
2
7.53, H 3.36, N 5.83; found: C 57.46, H 3.31, N 5.85.
Acknowledgement
10. B.P. Bandgar and K.A. Shaikh. Tetrahedron Lett. 44, 1959
2003).
(
The authors are grateful to the Research Council of
Guilan University for the partial support of this study.
1
1. S.-I. Murahashi, T. Naota, H. Taki, M. Mizuno, H. Takaya, S.
Komiya, Y. Mizuho, N. Oyasato, M. Harioka, M. Hirano, and
A. Fukuoka. J. Am. Chem. Soc. 117, 12436 (1995).
1
2. N. Komiya, S. Noji, and S.-I. Murahashi. Chem. Commun.
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©
2006 NRC Canada