Catalyst-free one-pot four component synthesis of polysubstituted imidazoles in neutral ionic liquid 1-butyl-3-methylimidazolium bromide

Article abstract of DOI:10.1021/cc100097m

A catalyst-free one-pot four component methodology for the synthesis of 1,2,4,5-substituted imidazoles under conventional heating and microwave irradiation using 1-butyl-3-methylimidazolium bromide, [Bmim]Br, as a neutral reaction media is described. A broad range of structurally diverse aldehydes (aromatic aldehydes bearing electron withdrawing and/or electron releasing groups as well as heteroaromatic aldehydes) and primary amines (aromatic and aliphatic) were applied successfully, and corresponding products were obtained in good to excellent yields without any byproduct.

Full text of DOI:10.1021/cc100097m

844
J. Comb. Chem. 2010, 12, 844–849
Catalyst-Free One-Pot Four Component Synthesis of Polysubstituted
Imidazoles in Neutral Ionic Liquid 1-Butyl-3-methylimidazolium
Bromide
Alireza Hasaninejad,*,† Abdolkarim Zare,‡ Mohsen Shekouhy,† and Javad Ameri Rad†
Department of Chemistry, Faculty of Sciences, Persian Gulf UniVersity, Bushehr 75169, Iran, and
Department of Chemistry, Payame Noor UniVersity (PNU), Iran
ReceiVed June 3, 2010
A catalyst-free one-pot four component methodology for the synthesis of 1,2,4,5-substituted imidazoles
under conventional heating and microwave irradiation using 1-butyl-3-methylimidazolium bromide, [Bmim]Br,
as a neutral reaction media is described. A broad range of structurally diverse aldehydes (aromatic aldehydes
bearing electron withdrawing and/or electron releasing groups as well as heteroaromatic aldehydes) and
primary amines (aromatic and aliphatic) were applied successfully, and corresponding products were obtained
in good to excellent yields without any byproduct.
1. Introduction
Imidazoles are an important group of five member nitrogen
heterocycles that have attracted much attention because of
the participation in the structure of biological active mol-
ecules such as Histidine, Histamine, and Biotin.15 Therewith,
imidazole moiety is the core structure of many important
drugs such as Losartan, Olmesartan, Eprosartan, and
Trifenagrel.16 Beside these, the application of imidazoles as
greener solvents by means of ILs17 and N-heterocyclic
carbenes in organometallic chemistry has been abundant.18
Industrial and academic studies for the preparation of 1,2,4,5-
substituted imidazoles has led to numerous methodologies
for the synthesis of these compounds.19,20 The most well-
known and classical method for preparation of these com-
pounds involves four-component condensations of a 1,2-
diketone derivative with an aldehyde, primary amine, and
ammonium acetate in refluxing HOAc, which is known to
have poor yields and long reaction times.21 Many new
methodologies were developed to improve the yield of this
reaction using other catalytic conditions, such as FeCl3 ·
6H2O,22 heteropolyacid,23 silica gel,24 zeolite,24 alumina,25
HClO4 · SiO2,26 molecular iodine,27 BF3 · SiO2,28 InCl3 ·
3H2O,29 K5CoW12O40 · 3H2O,30 copper acetate,31 and trif-
luoroacetic acid32 under microwave-irradiated, solvent-free
or classical conditions. However, most of these methodolo-
gies suffer from various drawbacks, such as laborious and
complex workup and purification, significant amounts of
waste materials, strongly acidic conditions and occurrence
of side reactions, poor yields, and the use of expensive
reagents.
Multicomponent reactions (MCRs) play an important role
in combinatorial chemistry because of the ability to synthe-
size target compounds with greater efficiency and atom
economy by generating structural complexity in a single step
from three or more reactants. Moreover, MCRs offer the
advantage of simplicity and synthetic efficiency over con-
ventional chemical reactions.1
The use of ionic liquids (ILs) as greener solvents in organic
reactions is in combination with some advantages such as
control of product distribution,2 enhanced rate3 and/or
reactivity,4 ease of product recovery,5 catalyst immobiliza-
tion,6 and recycling.7 Since ILs are neither completely non-
volatile nor non-flammable, use of ILs omits the risk of
combustion by replacement of volatile organic compounds
widely used as solvents in organic reactions.
In parallel with the use of ILs in organic transformations,
catalyst-free methodologies for the synthesis of organic
compounds have attracted much interest because of their ease
of experimental procedures as well as workup, low cost,
possibility of using acid or base sensitive substrates, and
environmentally benign nature.8 Many organic transforma-
tions were studied under catalyst-free conditions such as
synthesis of 2-amino thiazols,9 N-benzyloxycarbonylation of
amines,10 synthesis of benzoic and benzyl esters,11 gem-
bisillylation of carboxylic acids,12 synthesis of polyorgano-
syloxanes,13 and so forth. As a part of our continuing studies
in developing efficient catalyst-free synthetic methodologies
in organic preparations,14 we found that synthesis of
polysubstituted imidazoles via a one-pot four component
reaction can be efficiently achieved without any catalyst with
the use of neutral ILs under microwave irradiation and/or
conventional heating.
On the basis of the above advantages of ILs, multicom-
ponent and catalyst-free reactions, herein we report a green,
facile and efficient catalyst-free procedure for the synthesis
of a wide range of structurally diverse 1,2,4,5-substituted
imidazoles via a four component one-pot reaction under
microwave radiation and/or conventional heating.
* To whom correspondence should be addressed. E-mail: ahassaninejad@
yahoo.com. Phone: +98(771)4222319. Fax: +98(771)4541494.
† Persian Gulf University.
‡ Payame Noor University.
10.1021/cc100097m  2010 American Chemical Society
Published on Web 09/09/2010

Synthesis of Polysubstituted Imidazoles
Journal of Combinatorial Chemistry, 2010 Vol. 12, No. 6 845
Scheme 1. One-Pot Four Component Reaction between
Benzil (1 mmol), Benzaldehyde (1 mmol), Aniline (1 mmol),
and Ammonium Acetate (1 mmol) in the Presence of
[Bmim]Br (0.5 g) under Conventional Heating Conditions
Scheme 2. Synthesis of 1,2,4,5-Tetrasubstituted Imidazoles
via a One-Pot Four Component Condensation Reaction in
the Presence of [Bmim]Br (0.5 g) As a Neutral Reaction
Media under Catalyst-Free Conditions at 140°C and/or under
Microwave Irradiation at 150 °C
known to reduce side reactions, increase yields, and improve
reproducibility.36 Microwave-enhanced chemistry in this
reaction is based on the efficient heating of materials by
“microwave dielectric heating” effects. This phenomenon
refers to the ability of IL to absorb microwave energy and
convert it into heat.36 Traditionally, organic synthesis is
carried out by conductive heating with an oil bath. This is a
comparatively slow and inefficient method for transferring
energy into the system, since it depends on the thermal
conductivity of the various materials that must be penetrated
and results in the temperature of the reaction vessel being
higher than that of the reaction mixture. In contrast,
microwave irradiation produces efficient internal heating (in-
core volumetric heating) by direct coupling of microwave
energy with the molecules that are present in the reaction
mixture. These effects should be termed “specific microwave
effects”. In this category fall, for example, the formation of
“molecular radiators” by direct coupling of microwave
energy to IL in homogeneous solution (microscopic
hotspots),37 and the elimination of wall effects caused by
inverted temperature gradients.38 Because of the strong
microwave absorptivity of ILs and the delay experienced in
monitoring temperature, the temperature measurement in
MW experiments with ILs might be erroneous.39
2. Results and Discussion
To find the best conditions for the synthesis the titled
compounds, one-pot four component reaction between benzil
(1) (1 mmol), benzaldehyde (2) (1 mmol), aniline (3) (1
mmol), and ammonium acetate (4) (1 mmol) in the presence
of 1-butyl-3-methylimidazolium bromide {[Bmim]Br} (0.5
g) to form the product 5aa (Scheme 1) was selected as a
model reaction, and the yield and reaction time were
monitored at the various temperatures; the obtained results
are summarized in Table 1.
As can be seen from Table 1, the maximum reaction rate
as well as yield was obtained in 140 °C. The model reaction
was also examined without use of the microwave irradiation
at room temperature, and the reaction did not occur at all
even after 2 days. The same results have been obtained when
we used 4-nitrobenzaldehyde as a most reactive aldehyde
instead of benzaldehyde.
During the past two decades many investigations have
established the critical role of microwave irradiation in the
rate acceleration of diverse chemical reactions.14,32-36
Considering this fact, we decided to examine our methodol-
ogy under microwave irradiation. For this purpose the above
model reaction was subjected to microwave irradiation, and
after screening the microwave irradiation power, we found
that the optimum reaction conditions were 150 °C for 5 min
with the maximum power of 200 W. Increasing the temper-
ature did not have an effect on the yield of product or reaction
time.
Use of microwave irradiation instead of conventional
heating provides for a rate enhancement as we expect, but
synthesis of organic compounds under microwave irradiation
has been limited by the need for a specialized apparatus that
may not be accessible in many laboratories. Because of this
limitation, herein we report both conventional and microwave
heating for the synthesis of the titled compounds.
Not only is direct microwave heating able to reduce
chemical reaction times from hours to minutes, but it is also
The scope and efficiency of the process was explored
under the optimized conditions. For this purpose, a broad
range of structurally diverse aromatic aldehydes as well as
amines (aliphatic or aromatic) were condensed with benzil
and ammonium acetate under conventional heating or
microwave irradiation (Scheme 2), and the results are
displayed in Table 2.
Table 1. One-Pot Four Component Reaction between Benzil (1
mmol), Benzaldehyde (1 mmol), Aniline (1 mmol), and
Ammonium Acetate (1 mmol) in the Presence of [Bmim]Br (0.5
g) at Various Temperatures under Conventional Heating or
Microwave Irradiation
conventional heating
MW
entry temperature (°C) time (h) yielda (%) time (min) yielda (%)
The yields obtained were good to excellent without
formation of any side products such as 2,4,5- trisubstituted
imidazoles, which are normally observed under the influence
of strong acids.40 Aromatic aldehydes having electron
withdrawing groups (Table 2, entries 5ak, 5al, 5ay) reacted
at faster rate compared with aromatic aldehydes substituted
with electron releasing groups (Table 2, entries 5ap, 5ar, 5at,
5au). Moreover, neutral conditions of our methodology make
1
2
3
4
5
6
7
8
80
90
5
5
5
5
42
44
58
61
79
89
91
91
15
15
15
15
12
8
25
32
39
45
68
71
85
89
100
110
120
130
140
150
5
3.5
2.5
2.5
5
5
a Isolated yield.

846 Journal of Combinatorial Chemistry, 2010 Vol. 12, No. 6
Hasaninejad et al.
Table 2. Synthesis of 1,2,4,5-Tetrasubstituted Imidazoles via a One-Pot Four Component Condensation Reaction in the Presence of
[Bmim]Br (0.5 g) as a Neutral Reaction Media under Catalyst-Free Conditions at 140°C and/or under Microwave Irradiation at 150 °C
conventional heating
MW
M.P. (°C)
entry
R1
R2
C6H5
CH3
C6H5CH2
CH3
C2H5
iso-C4H9
C6H5
C6H5CH2
CH3
4-Cl-C6H4
4-CH3-C6H4
4-CH3-C6H4
C6H5CH2
4-F-C6H4
4-CH3-C6H4
C6H5CH2
C6H5CH2
cyclohexyl
C6H5CH2
C6H5CH2
C6H5CH2
C6H5
4-CH3-C6H4
4-OH-C6H4
4-CH3-C6H4
4-CH3-C6H4
4-CH3-C6H4
4-CH3-C6H4
time (h)
yielda(%)
time (min)
yielda (%)
found
reportedref.
5aa
5ab
5ac
5ad
5ae
5af
5ag
5ah
5ai
5aj
5ak
5al
5am
5an
5ao
5ap
5aq
5ar
C6H5
C6H5
C6H5
2.5
3
2
3.5
3.5
3.5
2.5
2
4
3
2
1.5
2.5
3
3
4
2.5
4.5
2
4
3
4.5
2
2
1.5
2.5
3.5
5
91
87
90
89
85
88
92
90
82
93
92
93
89
92
90
82
90
82
89
85
89
87
90
91
90
88
90
86
5
6
4
7
7
7
5
5
8
5
4
3
5
5
4
6
5
7
4
6
6
7
4
4
5
5
6
7
89
88
91
87
82
88
90
88
89
90
91
93
91
92
92
90
91
89
91
89
87
89
90
93
90
90
91
89
219-221
144-146
157-159
210-213
127-129
155-156
191-192
166-168
200-203
189-191
145-147
215-217
161-163
198-201
194-196
131-132
149-151
163-165
159-161
136-138
159-161
283-284
199-202
289-290
198-201
235-237
215-217
218-220
21823
144-14523
158-16023
208-21143
124-12643
151-15343
18923
4-CH3-C6H4
4-CH3-C6H4
4-CH3-C6H4
4-CH3-C6H4
4-CH3-C6H4
4-Br-C6H4
165-16623
201-20223
187-18943
149-15143
219-22043
156-15843
196-19743
188-19143
128-13026
146-14826
16426
4-Cl-C6H4
3-NO2-C6H4
4-NO2-C6H4
4-Cl-C6H4
4-Cl-C6H4
4-CH3-C6H4
3-OCH3-C6H4
4-Cl-C6H4
4-CH3-C6H4
2-furyl
4-OH-C6H4
4-OCH3-C6H4
4-OH-C6H4
2-thienyl
5as
5at
156-15726
134-13526
157-16025
280-28128
5au
5av
5aw
5ax
5ay
5az
5ba
5bb
2-thienyl
4-CN-C6H4
3-OH-C6H4
4-CH(CH3)2-C6H4
3-indolyl
230-23230
a Isolated yields.
Scheme 3. Condensation Reaction between Diacetyl (6), Benzaldehyde (2), Aniline (3), and Ammonium Acetate (4) at 140 °C
in [Bmim]Br
it possible to use acid or base sensitive aldehydes without
side reactions and/or byproduct (Table 2, entry 5ay). Beside
this, our methodology has been used successfully for
heteroaromatic aldehydes, and corresponding imidazoles
were obtained in excellent yields and without any byproduct.
(Table 2, entries 5as, 5aw, 5ax, 5bb). All the products
obtained were fully characterized by 1H NMR and 13C NMR
spectroscopy and by comparison with the reported spectral
data.
The condensation reaction between diacetyl (6) (1 mmol)
as an aliphatic/enolizable alpha-diketone, benzaldehyde (2)
(1 mmol), aniline (3) (1 mmol), and ammonium acetate (4)
(1 mmol)in [Bmim]Br (0.5 g) has been examined at 140 °C;
the corresponding product was obtained in 75% yield after
8 h (Scheme 3), but under microwave irradiation a mixture
of unknown products was obtained.
serves two catalytic functions; first, to electrophilically
activate the aldehyde carbonyl through hydrogen-bonding
to the carbonyl oxygen, and second, to enhance the nucleo-
philicity of the amine through deprotonation of the N-H
bond, as shown in the first step of Scheme 4. To demonstrate
the favorable reasons for using [Bmim]Br as a reaction
medium (“greenness”, solvent recoverability, non-inflam-
mability, etc.) the model system was done under parallel
conditions in other organic media such as dimethylsulfoxide
(DMSO), dimethylformamide (DMF), CH3CN, and toluene,
and the results were summarized in Table 3. These results
show that the IL improves the yield and rate of the reaction
process. Moreover, these results confirm that the IL [Bmim-
]Br truly has chemical advantages such as faster speed and
catalytic properties as shown in Scheme 4.
Many recent studies have established that hydrogen
bonding can occur between the solute and the cationic or
anionic component of ILs.41 Moreover Deb and Bhuyan have
suggested for the synthesis of bis(indolyl)methanes via
condensation of indoles with aldehydes that hydrogen bond
formation between a carbonyl group and solvent leads to
activation of aldehydes.42 According to these observations,
we suggest a mechanism for this reaction in which the IL
3. Conclusions
In conclusion, an extremely efficient method has been
developed for the synthesis of tetra-substituted imidazoles
in [Bmim]Br under conventional heating as well as micro-
wave irradiation and catalyst-free conditions. This method
is bestowed with several unique merits, such as high
conversions, simplicity in operation, cost efficiency, and use

Synthesis of Polysubstituted Imidazoles
Journal of Combinatorial Chemistry, 2010 Vol. 12, No. 6 847
Scheme 4. Suggested Mechanism for the Synthesis of Polysubstituted Imdazoles in the Presence of [Bmim]Br
Table 3. One-Pot Four Component Reaction between Benzil (1
mmol), Benzaldehyde (1 mmol), Aniline (1 mmol), and
Ammonium Acetate (1 mmol) in the Presence of Different
Solvents under Thermal Conditions
s-40 s-30 s). After this, the reaction mixture was allowed
to cool to room temperature; water (20 mL) was added and
stirred magnetically for 5 min. Insoluble crude products were
filtered, dried, and recrystallized from ethanol or ethyl
acetate. To recover the [Bmim]Br, after the isolation of
insoluble products, water was evaporated, and the remaining
viscous liquid was washed with ethyl acetate (5 mL) and
dried under reduced pressure ([Bmim]Br was recovered in
97% yield).
4.2. Selected Spectral Data. 1-Methyl-2,4,5-triphenyl-
1H-imidazole (5ab). 1H NMR (500 MHz, DMSO-d6) δ: 3.58
(s, 3H), 7.37-7.41 (m, 3H), 7.43-7.45 (m, 2H), 7.58-7.60
(m, 5H), 7.72-7.73 (m, 3H), 7.94-7.96 (m, 2H). 13C NMR
(125 MHz, DMSO-d6) δ: 34.8, 124.5, 127.6, 128.4, 128.6,
129.4, 129.6, 129.7, 129.8, 130.0, 130.2, 130.8, 131.1,
131.82, 131.85, 132.6, 145.5.
1-Methyl-4,5-diphenyl-2-p-tolyl-1H-imidazole (5ad). 1H
NMR (500 MHz, DMSO-d6) δ: 2.45 (s, 3H), 3.56 (s, 3H),
7.34-7.38 (m, 5H), 7.44-7.47 (m, 3H), 7.50-7.55 (m, 4H),
7.58-7.60 (m, 2H). 13C NMR (125 MHz, DMSO-d6) δ: 21.9,
34.7, 128.5, 129.6, 129.7, 130.2, 130.5, 130.7, 131.0, 131.72,
131.77, 145.6.
1,4,5-Triphenyl-2-p-tolyl-1H-imidazole (5ag). 1H NMR
(500 MHz, DMSO-d6) δ: 2.26 (s, 3H), 7.08 (d, J ) 8.0 Hz,
2H), 7.16-7.18 (m, 1H), 7.22-7.25 (m, 6H), 7.26-7.28 (m,
5H), 7.31-7.32 (m, 3H), 7.50 (d, J ) 8.0 Hz, 2H). 13C NMR
(125 MHz, DMSO-d6) δ: 21.5, 127.2, 128.4, 128.9, 129.0,
129.2, 129.50, 129.58, 129.6, 129.9, 131.3, 131.9, 132.0,
135.3, 137.60, 137.63, 138.6, 147.0.
solvent
(5 g)
reaction
conditions
time
(h)
yielda
(%)
entry
1
2
3
4
5
DMSO
DMF
CH3CN
toluene
[Bmim]Br
140 °C
140 °C
reflux
reflux
140 °C
24
24
12
24
2.5
no reaction
21
27
no reaction
91
a Isolated yields.
of [Bmim]Br as a solvent, and thus significantly contributes
to the practice of green chemistry. The use of [Bmim]Br as
a non-volatile medium, simple workup, neutral reaction
conditions, and high yields of the products make our
methodology a valid contribution to the existing processes
in the field of imidazole synthesis.
4. Experimental Section
All chemicals were purchased from Merck or Fluka
Chemical Companies. The IL was prepared according to the
reported method.44 All reactions were carried out using a
laboratory microwave oven (MicroSYNTH, Milestone Com-
1
pany, Italy).The H NMR (500 MHz) and 13C NMR (125
MHz) were run on a Bruker Avance DPX-250, FT-NMR
spectrometer (δ in ppm). Melting points were recorded on a
Bu¨chi B-545 apparatus in open capillary tubes.
4.1. General Procedure. Benzil (1 mmol), aldehyde (1
mmol), primary amine (1 mmol), and ammonium acetate (1
mmol) were added to [Bmim]Br (0.5 g) in a 25 mL round-
bottom flask equipped with a condenser. The resulting
mixture was heated to 140 °C for the appropriate times
reported in Table 2. In the case of microwave irradiation,
the resulting mixture was transferred to a sealed tube and
exposed to microwave irradiation for appropriate times
reported in Table 2 in a multistep mode with interval (30
1-Benzyl-4,5-diphenyl-2-p-tolyl-1H-imidazole (5ah). 1H
NMR (500 MHz, DMSO-d6) δ: 2.33 (s, 3H), 5.14 (s, 2H),
7.13-7.16 (m, 2H), 7.18-7.21 (m, 2H), 7.24-7.29 (m 4H),
7.32-7.35 (m, 3H), 7.39-7.44 (m, 6H), 7.54 (d, J ) 8.0
Hz, 2H).
2-(4-Bromophenyl)-1-methyl-4,5-diphenyl-1H-imida-
1
zole (5ai). H NMR (500 MHz, DMSO-d6) δ: 3.47 (s, 3H),

848 Journal of Combinatorial Chemistry, 2010 Vol. 12, No. 6
Hasaninejad et al.
7.13 (t, J ) 7.2 Hz, 1H), 7.21 (t, J ) 7.2 Hz, 2H), 7.43-7.45
(m, 4H), 7.48-7.55 (m, 3H), 7.72-7.77 (m, 4H). 13C NMR
(125 MHz, DMSO-d6) δ: 33.9, 122.9, 127.1, 128.9, 129.6,
129.9, 130.7, 131.44, 131.49, 131.5, 131.7, 132.4, 135.5,
137.5, 146.6.
129.6, 129.9, 130.6, 131.4, 131.5, 132.0, 135.5, 137.3, 137.7,
147.3, 158.4.
4,5-Diphenyl-2-(thiophen-2-yl)-1-p-tolyl-1H-imidazole
(5aw). 1H NMR (500 MHz, DMSO-d6) δ: 2.31 (s, 3H), 6.51
(d, J ) 3.5 Hz, 1H), 6.62 (t, J ) 4.5 Hz, 1H), 7.18-7.29
(m, 12H), 7.47-7.50 (m, 3H). 13C NMR (125 MHz, DMSO-
d6) δ: 21.6, 126.1, 127.1, 127.3, 127.9, 128.3, 129.0, 129.3,
129.6, 130.8, 130.9, 131.9, 132.1, 133.8, 134.4, 134.9, 137.6,
139.9, 142.3.
1,2-Bis(4-chlorophenyl)-4,5-diphenyl-1H-imidazole (5aj).
1H NMR (500 MHz, DMSO-d6) δ: 7.17-7.19 (m, 1H),
7.23-7.25 (m, 4H), 7.29-7.32 (m, 5H), 7.38-7.42 (m, 6H),
7.50 (d, J ) 7.0 Hz, 2H). 13C NMR (125 MHz, DMSO-d6)
δ: 127.2, 127.4, 129.0, 129.2, 129.44, 129.49, 129.9, 130.1,
130.8, 130.9, 131.3, 132.0, 132.3, 134.1, 134.3, 135.0, 136.2,
145.8.
4-(4,5-Diphenyl-2-(thiophen-2-yl)-1H-imidazol-1-yl)phe-
1
nol (5ax). H NMR (500 MHz, DMSO-d6) δ: 6.58 (s, 1H),
6.77 (d, J ) 8.0 Hz, 2H), 6.95 (m, 1H), 7.18-7.50 (m, 13H),
9.88 (s, 1H). 13C NMR (125 MHz, DMSO-d6) δ: 116.7,
126.1, 127.1, 127.3, 127.8, 127.9, 128.3, 129.0, 129.23,
129.29, 131.0, 131.1, 131.9, 132.3, 133.9, 135.0, 137.4,
142.6, 158.9.
4-(4,5-Diphenyl-1-p-tolyl-1H-imidazol-2-yl)benzoni-
trile (5ay). 1H NMR (500 MHz, DMSO-d6) δ: 2.24 (s, 3H),
7.08-7.49 (m, 14H), 6.68 (d, J ) 7.5 Hz, 2H), 7.95 (d, J )
7.5 Hz, 2H). 13C NMR (125 MHz, DMSO-d6) δ: 21.4, 111.3,
115.2, 121.0, 127.12, 127.18, 128.7, 129.1, 129.36, 129.39,
130.1, 130.3, 131.1, 131.4, 132.0, 137.2, 138.7, 143.9, 147.5,
153.33, 153.66.
2-(3-Nitrophenyl)-4,5-diphenyl-1-p-tolyl-1H-imida-
1
zole (5ak). H NMR (500 MHz, DMSO-d6) δ: 7.32-7.39
(m, 6H), 7.54-7.56 (m, 8H), 7.77 (t, J ) 7.7 Hz, 1H), 8.20
(d, J ) 8.0 Hz, 1H), 8.52 (d, J ) 7.5 Hz, 1H), 8.95 (s, 1H).
2-(4-Nitrophenyl)-4,5-diphenyl-1-p-tolyl-1H-imida-
1
zole (5al). H NMR (500 MHz, DMSO-d6) δ: 2.28 (s, 3H),
7.15-7.20 (m, 5H), 7.24-7.27 (m, 4H), 7.31-7.32 (m, 3H),
7.50 (d, J ) 7.5 Hz, 2H), 7.63 (d, J ) 8.5 Hz, 2H), 8.14 (d,
J ) 9.0 Hz, 2H). 13C NMR (125 MHz, DMSO-d6) δ: 21.5,
124.3, 127.2, 127.6, 129.0, 129.1, 129.3, 129.5, 129.6, 130.7,
130.8, 131.9, 133.7, 134.5, 134.8, 137.3, 138.7, 139.5, 144.7,
147.5.
3-(4,5-Diphenyl-1-p-tolyl-1H-imidazol-2-yl)phenol (5az).
1H NMR (500 MHz, DMSO-d6) δ: 2.26 (s, 3H), 6.68-6.70
(m, 2H), 6.97-7.31 (m, 14H), 7.47 (d, J ) 7.5 Hz, 2H),
9.48 (s, 1H).
1-Benzyl-2-(4-chlorophenyl)-4,5-diphenyl-1H-imida-
zole (5am). 1H NMR (500 MHz, DMSO-d6) δ: 5.16 (s, 2H),
6.75 (d, J ) 7.0 Hz, 2H), 7.12-7.22 (m, 6H), 7.29-7.30
(m, 2H), 7.40-7.41 (m, 3H), 7.45-7.50 (m, 4H), 7.68 (d, J
) 8.0 Hz, 2H). 13C NMR (125 MHz, DMSO-d6) δ: 48.6,
126.5, 127.0, 127.2, 128.1, 128.9, 129.4, 129.5, 129.8, 130.5,
131.0, 131.3, 131.4, 131.6, 134.4, 135.2, 137.9, 146.7.
4,5-Diphenyl-1,2-dip-tolyl-1H-imidazole (5ao). 1H NMR
(500 MHz, DMSO-d6) δ: 2.25 (s, 3H), 2.26 (s, 3H),
7.08-7.10 (m, 6H), 7.15-7.17 (m, 1H), 7.21-7.24 (m, 5H),
7.47-7.49 (m, 2H). 13C NMR (125 MHz, DMSO-d6) δ: 21.4,
21.5, 127.2, 128.6, 128.9, 129.0, 129.1, 129.2, 129.3, 129.5,
130.4, 131.4, 132.0, 135.0, 135.4, 137.5, 138.5, 138.8, 147.0.
2-(4-Isopropylphenyl)-4,5-diphenyl-1-p-tolyl-1H-imida-
zole (5ba). 1H NMR (500 MHz, DMSO-d6) δ: 1.16 (s, 3H),
1.18 (s, 3H), 2.26 (s, 3H), 2.84-2.86 (m, 1H), 7.13-7.33
(m, 16H), 7.48 (d, J ) 7.5 Hz, 2H). 13C NMR (125 MHz,
DMSO-d6) δ: 21.5, 24.5, 33.9, 126.9, 127.1, 127.2, 128.93,
128.98, 129.0, 129.2, 129.30, 129.35, 130.5, 131.4, 132.00,
132.06, 135.0, 135.3, 137.5, 138.9, 146.9, 149.3.
3-(4,5-Diphenyl-1-p-tolyl-1H-imidazol-2-yl)-1H-indole
(5bb). 1H NMR (500 MHz, DMSO-d6) δ: 2.32 (s, 3H), 6.24
(s, 1H), 7.17-7.39 (m, 15H), 7.58 (d, J ) 7.5 Hz, 2H), 8.59
(d, J ) 8.0 Hz, 1H). 13C NMR (125 MHz, DMSO-d6) δ:
21.6, 106.6, 112.3, 120.7, 122.7, 122.9, 124.2, 126.9, 127.0,
129.0, 129.3, 129.7, 130.3, 130.8, 131.7, 132.0, 135.4, 135.8,
136.3, 137.0, 139.3, 144.4.
1-Benzyl-2-(3-methoxyphenyl)-4,5-diphenyl-1H-imida-
zole (5ap). 1H NMR (500 MHz, DMSO-d6) δ: 3.68 (s, 3H),
5.16 (s, 2H), 6.79 (d, J ) 7.5 Hz, 2H), 6.98-7.00 (m, 1H),
7.13-7.16 (m, 3H), 7.17-7.25 (m, 5H), 7.29-7.35 (m, 3H),
7.40-7.41 (m, 3H), 7.46-7.47 (m, 2H). 13C NMR (125
MHz, DMSO-d6) δ: 48.6, 55.9, 114.6, 115.6, 121.7, 126.4,
127.0, 127.1, 128.0, 128.9, 129.4, 129.74, 129.78, 130.5,
131.1, 131.4, 131.7, 132.8, 135.4, 137.7, 138.2, 147.7, 160.0.
4,5-Dimethyl-1,2-diphenyl-1H-imidazole (5bc). 1H NMR
(500 MHz, DMSO-d6) δ: 2.06 (s, 3H), 2.21 (s, 3H),
7.18-7.20 (m, 3H), 7.25-7.27 (m, 5H), 7.41-7.42 (m, 2H).
Acknowledgment. The authors thank the Research Com-
mittee of Persian Gulf University and Payame Noor Uni-
versity (PNU) of Bushehr for financial support of this work.
1-Benzyl-2-(4-methoxyphenyl)-4,5-diphenyl-1H-imida-
zole (5au). 1H NMR (500 MHz, DMSO-d6) δ: 3.77 (s, 3H),
5.13 (s, 2H), 6.76 (d, J ) 7.0 Hz, 2H), 6.90 (d, J ) 9.0 Hz,
2H), 7.11-7.21 (m, 6H), 7.26-7.28 (m, 2H), 7.38-7.39 (m,
Supporting Information Available. Representative ex-
perimental procedures and spectral data of compounds 5ab,
5ad, 5ag, 5ah-5am, 5ao, 5ap, 5au-5az and 5ba-5bc. This
material is available free of charge via the Internet at http://
pubs.acs.org.
3H), 7.46 (d, J ) 7.0 Hz, 2H), 7.58 (d, J ) 9.0 Hz, 2H). 13
C
NMR (125 MHz, DMSO-d6) δ: 48.5, 56.0, 114.9, 124.0,
126.4, 126.9, 127.0, 128.0, 128.9, 129.3, 129.6, 129.7, 130.6,
130.8, 131.6, 131.7, 135.5, 137.5, 138.3, 147.9, 160.5.
1
4-(1,4,5-Triphenyl-1H-imidazol-2-yl)phenol (5av). H
References and Notes
NMR (500 MHz, DMSO-d6) δ: 6.64 (d, J ) 9.0 Hz, 2H),
7.14-7.24 (m, 9H), 7.27-7.28 (m, 3H), 7.30-7.32 (m, 3H),
7.48 (d, J ) 7.0 Hz, 2H), 9.60 (s, 1H). 13C NMR (125 MHz,
DMSO-d6) δ: 115.8, 122.1, 127.1, 127.2, 128.9, 129.1, 129.3,
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