Efficient preparation of sulfonylimines, imidazoles and bis (indolyl)methanes catalyzed by [Et 3NSO 3H]Cl

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Efficient Preparation of Sulfonylimines,
Imidazoles and bis(Indolyl)methanes
Catalyzed by [Et3NSO3H]Cl
Abdolkarim Zare a , Firoozeh Bahrami a , Maria Merajoddin a
,
Marzieh Bandari a , Ahmad Reza Moosavi-Zare b , Mohammad Ali
Zolfigol c , Alireza Hasaninejad d , Mohsen Shekouhy d , Mohammad
Hassan Beyzavi e , Vahid Khakyzadeh c , Mohammad Mokhlesi c
Zhila Asgari c
&
a Department of Chemistry , Payame Noor University , PO BOX
19395-3697, Tehran , Iran
b Department of Chemistry , University of Sayyed Jamaleddin
Asadabadi , Asadabad , 6541835583 , Iran
c Faculty of Chemistry , Bu-Ali Sina University , Hamedan ,
6517838683 , Iran
d Department of Chemistry, Faculty of Sciences , Persian Gulf
University , Bushehr , 75169 , Iran
e Institut für Chemie und Biochemie, Freie Universität Berlin ,
Takustr. 3, 14195 , Berlin , Germany
Published online: 16 May 2013.
To cite this article: Abdolkarim Zare , Firoozeh Bahrami , Maria Merajoddin , Marzieh Bandari ,
Ahmad Reza Moosavi-Zare , Mohammad Ali Zolfigol , Alireza Hasaninejad , Mohsen Shekouhy ,
Mohammad Hassan Beyzavi , Vahid Khakyzadeh , Mohammad Mokhlesi & Zhila Asgari (2013): Efficient
Preparation of Sulfonylimines, Imidazoles and bis(Indolyl)methanes Catalyzed by [Et3NSO3H]Cl,
Organic Preparations and Procedures International: The New Journal for Organic Synthesis, 45:3,
211-219
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Organic Preparations and Procedures International, 45:211–219, 2013
Copyright © Taylor & Francis Group, LLC
ISSN: 0030-4948 print / 1945-5453 online
DOI: 10.1080/00304948.2013.764791
Efficient Preparation of Sulfonylimines, Imidazoles
and bis(Indolyl)methanes Catalyzed
by [Et3NSO3H]Cl
Abdolkarim Zare,1 Firoozeh Bahrami,1 Maria Merajoddin,1
Marzieh Bandari,1 Ahmad Reza Moosavi-Zare,2 Mohammad Ali
Zolfigol,3 Alireza Hasaninejad,4 Mohsen Shekouhy,4 Mohammad
Hassan Beyzavi,5 Vahid Khakyzadeh,3 Mohammad Mokhlesi,3
and Zhila Asgari3
1Department of Chemistry, Payame Noor University, PO BOX 19395-3697
Tehran, Iran
2Department of Chemistry, University of Sayyed Jamaleddin Asadabadi,
Asadabad 6541835583, Iran
3Faculty of Chemistry, Bu-Ali Sina University, Hamedan, 6517838683, Iran
4Department of Chemistry, Faculty of Sciences, Persian Gulf University,
Bushehr, 75169, Iran
5Institut fu¨r Chemie und Biochemie, Freie Universita¨t Berlin, Takustr. 3, 14195,
Berlin, Germany
Ionic liquids are of considerable current interest as benign reaction media because of
their unique properties such as non-volatility, non-flammability, safety and their ability to
dissolve a wide range of materials.1–4 Over the past decade, a variety of ionic liquids have
been shown to be efficient and practical alternatives to volatile organic solvents for many
important organic transformations.1–4 These green solvents have also been used as catalysts
in various organic reactions.5–11 As part of our ongoing program to extend applications of
ionic liquids in organic synthesis,8–10 we synthesized N,N-diethyl-N-sulfoethanammonium
chloride ([Et3NSO3H]Cl) as a new Brønsted acidic ionic liquid from triethylamine and
chlorosulfonic acid (Scheme 1), and applied it as an efficient catalyst for synthesis of β-
acetamido ketones and xanthene derivatives.11 We now report the use of this ionic liquid as
catalyst for the preparation of sulfonylimines, imidazoles and bis(indolyl)methanes.
Imines bearing electron-withdrawing N-substituents are useful intermediates in organic
synthesis;12 in particular, N-sulfonylimines have been subject of the attention for organic
chemists because the sulfonyl moiety is powerfully activates the C=N bond and thus these
Address correspondence to either Abdolkarim Zare, Department of Chemistry, Payame
Noor University, Po Box 19395-3697 Tehran, Iran. E-mail: abdolkarimzare@pnu.ac.ir; abdolka-
rimzare@yahoo.com or Mohammad Ali Zolfigol, Faculty of Chemistry, Bu-Ali Sina University,
Hamedan 6517838683, Iran. E-mail: mzolfigol@yahoo.com
211

212
Zare et al.
CH2Cl2
Et3N
+
ClSO3H
[Et3NSO3H]Cl
Scheme 1
compounds have been widely used as substrates in nucleophilic additions,13 reductions,14
aza Diels-Alder reactions,15 aziridine16 and oxaziridine synthesis.17 Several catalysts have
been used for condensation of sulfonamides with aldehydes to N-sulfonylimines.18–23
Imidazole derivatives display various pharmacological and biological activities,24,25
and also are an essential component of many biologically active compounds and drugs
such as losartan, eprosartan,26 and trifenagrel,27 and of agrochemical28 and plant
growth regulators.29 2,4,5-triaryl-1H-imidazoles have been prepared from the reaction
of 1,2-diketones with aldehydes and ammonium acetate using Brønsted or Lewis acidic
catalysts.30–37
bis(Indolyl)methanes also possess a wide range of biological activities,38–40 and their
chemistry has been reviewed by Shiri et al.41 Several Brønsted or Lewis acidic catalysts
have been used to effect the condensation of indoles with carbonyl compounds.9,41–43
Nevertheless, most of the reported catalysts for these condensations have one or more of
the following disadvantages: (i) lack of generality, (ii) long reaction time, (iii) low yield,
(iv) the use of large amount of catalyst, (v) drastic reaction conditions, (vi) application
of expensive, non-available, corrosive and air-sensitive catalysts. Thus, newer methods
involving experimental simplicity, effectiveness and novelty continue to attract attention.
To extend the applications of our catalyst, N,N-diethyl-N-sulfoethanammonium chlo-
ride ([Et3NSO3H]Cl) in organic synthesis, we tested its efficiency to catalyze the synthesis
of N-sulfonylimines (Scheme 2). Thus, the condensation of p-toluenesulfonamide with ben-
zaldehyde was examined in the presence of different amounts of [Et3NSO3H]Cl at range
of 25 to 90◦C under solvent-free conditions (Table 1). The best results were obtained when
the reaction was carried out using 25 mol% of the catalyst at 80◦C (Table 1, Entry 3).
Moreover, increasing the amount of [Et3NSO3H]Cl or the temperature did not improve
Table 1
Reaction of p-Toluenesulfonamide with Benzaldehyde in the Presence of Different Molar
Ratios of [Et3NSO3H]Cl at Range of 25◦ to 90◦C
Entry
Mol% of [Et3NSO3H]Cl
Temp.(◦C)
Yield (%)
Time (min)
1
2
3
4
5
6
7
8
10
20
25
27.5
25
25
80
80
80
80
25 (r.t.)
50
73
90
92
92
47
65
86
91
100
60
45
45
120
90
25
25
70
90
60
45

Sulfonylimines, Imidazoles and bis(Indolyl)methanes
213
[Et3NSO3H]Cl (25 mol%)
Ar SO2
NH2
+
Ar' CHO
Ar SO2
N
Solvent-free, 80 or 100 °C
Ar'
1a-n
Scheme 2
the results. Then, sulfonamides were treated with different aromatic aldehydes as well as
isatin (Table 2). As Table 2 indicates, p-toluenesulfonamide and benzenesulfonamide were
efficiently condensed with aromatic aldehydes possessing electron-withdrawing, electron-
releasing and halo substituents as well as with isatin, and the desired N-sulfonylimines
were produced in good to excellent yields within 45–120 min; the reaction was performed
at 100◦C with benzenesulfonamide (Table 2, compounds 1j-n).
We investigated the reaction of benzil with benzaldehyde and ammonium acetate using
different molar ratios of [Et3N-SO3H]Cl at range of 50–110◦C in the absence of solvent
(Scheme 3). Higher yield and shorter reaction time were obtained using 25 mol% of the
catalyst at 100◦C; in these conditions, the respective 2,4,5-triaryl-1H-imidazole (2a) was
produced in 93% yield within 120 min.
The results are displayed in Table 3 shows that the reaction of benzil with vari-
ous aromatic aldehydes and ammonium acetate under the optimized reaction conditions
Table 2
Solvent-free Synthesis of N-Sulfonylimines by Condensation of Sulfonamides with
Aldehydes as well as Isatin in the presence of [Et3N-SO3H]Cl
Cmpd
Ar
Arꢀ
Yield (%) Time (min) mp. (ºC) Lit. (ºC)
1a
1b
1c
1d
1e
1f
1g
1h
1i
1j
1k
1l
1m
1n
p-MeC6H4
p-MeC6H4
p-MeC6H4
p-MeC6H4
C6H5
92
94
93
91
88
91
94
96
83
90
87
90
94
90
45
40
50
90
90
120
50
60
80
60
100
60
50
70
107–109 (107–109)18
102–104 (101–102)23
163–165 (164–166)18
112–114 (111–112)23
109–111 (113–115)20
126–128 (128–129)23
125–127 (128–129)22
167–169 (172–173)23
97–99
77–79
164–166 (165–166)18
113–115 (113–115)18
130–132 (131–133)18
142–143 (143–144)18
m-NO2C6H4
p-NO2C6H4
p-MeC6H4
p-MeC6H4 p-[(CH3)2CH]C6H4
p-MeC6H4
p-MeC6H4
p-MeC6H4
p-MeC6H4
C6H5
p-MeOC6H4
p-ClC6H4
p-ClC6H4
p-CHOC6H4
C6H5
p-NO2C6H4
p-MeC6H4
p-ClC6H4
(98–100)18
(76–78)18
C6H5
C6H5
C6H5
Ph SO2
N
O
NH

214
Ph
Zare et al.
O
O
Ph
Ph
N
[Et3NSO3H]Cl (25 mol%)
Solvent-free, 100 °C
Ar' CHO
NH4OAc
Ar'
+
+
N
H
Ph
2a-l
Scheme 3
R'
R
O
[Et3NSO3H]Cl (25 mol%)
Solvent-free, r.t.
X
+
R
R'
N
N
H
N
H
H
Y
Y
3a-n
Scheme 4
proceeded efficiently to give corresponding imidazole derivatives in good to excellent yields
in relatively short reaction times.
We then examined [Et3N-SO3H]Cl for the preparation of bis(indolyl)methanes via the
reaction of indoles with aldehydes as well as ketones (Scheme 4). Thus, the reaction of
indole with benzaldehyde was tested in the presence of different amounts of [Et3N-SO3H]Cl
at room temperature under solvent-free conditions to provide compound 3a. The results
showed that 25 mol% of the catalyst was sufficient to efficiently catalyze this reaction; using
this amount of [Et3N-SO3H]Cl yielded compound 3a in 96% within 3 min. The reaction
of indole and 2-methylindole with a range of aromatic and aliphatic aldehydes as well
Table 3
Condensation of Benzil with Aldehydes and Ammonium Acetate
Cmpd
Arꢀ
Yield (%)
Time (min)
mp. (◦C)
Lit. (◦C)
2a
2b
2c
2d
2e
2f
2g
2h
2i
C6H5
93
92
92
89
88
85
81
84
90
88
84
87
120
100
100
120
120
120
120
120
120
120
120
120
273–275
312–314
203–205
230–232
219–221
256–258
235–237
192–194
286–288
262–264
188–190
256–258
(277–278)37
(>300)36
(200–202)37
(227–229)33
(225)35
(258–260)36
(232–233)36
(195–197)37
(280–283)33
(259–261)33
(189–190)37
(260–262)37
m-NO2C6H4
p-NO2C6H4
p-MeC6H4
p-MeOC6H4
m-HOC6H4
p-HOC6H4
o-ClC6H4
m-ClC6H4
p-ClC6H4
p-FC6H4
2j
2k
2l
p-BrC6H4

Sulfonylimines, Imidazoles and bis(Indolyl)methanes
215
Table 4
Solvent-free Preparation of bis(Indolyl)methanes from Indoles and Carbonyl Compounds
Cmpd
X
R
Rꢀ Yield (%) Time (min) mp. (◦C)
Lit. (◦C)
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
H
H
H
H
H
H
H
H
H
Me
Me
Me
H
C6H5
o-NO2C6H4
m-NO2C6H4
p-NO2C6H4
p-MeC6H4
p-MeOC6H4
o-ClC6H4
p-ClC6H4
CH3(CH2)3CH2
C6H5
H
H
H
H
H
H
H
H
H
H
H
H
Me
96
93
96
95
93
94
94
95
89
93
93
92
79
85
3
3
3
3
3
4
3
3
5
4
4
4
15
12
139–141 (140–142)42
137–139 (139–141)43
220–222 (220–222)42
218–220 (217–219)9
96–98
185–187 (185–187)9
(95–97)9
75–77
78–80
69–71
(74–76)43
(78–80)43
(71–73)43
246–248 (245–247)42
241–243 (241–243)42
173–175 (175–177)43
163–165 (164–166)42
164–166 (163–165)43
p-NO2C6H4
p-MeC6H4
C6H5
H
-CH2(CH2)3CH2-
as ketones furnished the desired bis(indolyl)methanes in 79–96% yields within 3–15 min
(Table 4).
The above observations confirmed the high efficiency and the generality of our catalyst,
[Et3NSO3H]Cl.
In another study, to recognize the essential role of [Et3NSO3H]Cl in the reactions,
the solvent-free condensation of indole with benzaldehyde was examined in the presence
of 25 mol% of the starting materials used for the preparation of the catalyst (NEt3 and
ClSO3H) as well as a possible product formed by the reaction of NEt3 with ClSO3H {this
possible product is [Et3NH][ClSO3]; however, this compound is not listed in the Chemical
Companies catalogs. Moreover, the acidic hydrogen of the cation of [Et3NH][ClSO3] can
catalyze the reaction, not its anion. Thus, we used [Et3NH]Cl instead of it}. The results
are presented in Table 5. As Table 5 indicates, [Et3NSO3H]Cl efficiently catalyzed the
reaction; Et3N could not catalyze the reaction; and ClSO3H as well as [Et3NH]Cl gave
Table 5
Condensation of Indole with Benzaldehyde using [Et3NSO3H]Cl, Et3N, ClSO3H and
[Et3NH]Cl at Room Temperature
Entry
Catalyst
Time (min)
Yield (%)
1
2
3
4
[Et3N-SO3H]Cl
NEt3
ClSO3H
3
60
5
96
—
45
63
[Et3N-H]Cl
30

216
Zare et al.
Table 6
Synthesis of Compounds 1a, 2a and 3a using [Et3NSO3H]Cl (25 mol%)
Cmpd
Amount of starting materials
Yield (%) Time (min)
1a
2a
p-MeC6H4SO2NH2 (10 mmol), PhCHO (10 mmol)
Benzil (10 mmol), PhCHO (10.5 mmol), NH4OAc
(40 mmol)
88
87
55
135
3a
Indole (20.5 mmol), PhCHO (10 mmol)
93
5
low yields of the product. These results confirmed the essential role of [Et3NSO3H]Cl to
catalyze the reactions.
As previously showed, [Et3NSO3H]Cl is highly efficient and general for the synthe-
sis of three important classes of organic compounds including N-sulfonylimines, 2,4,5-
triaryl-1H-imidazoles and bis(indolyl)methanes. To increase the value of the catalyst, its
regenerability and reusability were studied. For this purpose, the reaction of indole with
benzaldehyde using [Et3NSO3H]Cl was carried out several times, and the reaction mixtures
were combined. Afterward, H2O was added to the combined reaction mixtures, stirred for
3 min, and filtered (the catalyst is soluble in H2O; however, the reaction mixture is not solu-
ble in H2O). The filtrate (containing the catalyst) was basified by NaOH; in these conditions,
[Et3NSO3H]Cl was converted to Et3N and Na2SO4. Then, the solution was extracted with
CH2Cl2, washed with H2O and dried over Na2SO4. The recovered Et3N in CH2Cl2 was re-
acted with chlorosulfonic acid according to the described procedure to give [Et3NSO3H]Cl.
The catalytic activity of the regenerated catalyst was as same as the first one.
To recognize the applicability of our catalyst in larger scale synthesis, we examined
the synthesis of compounds 1a, 2a and 3a in scales reported in Table 6. As it is shown in
Table 6, the reactions were successfully performed at the larger scale without significant
loss of the yields or increase in the reaction times.
In summary, we have introduced ionic liquid [Et3NSO3H]Cl as a new Brønsted
acidic catalyst for the synthesis of N-sulfonylimines, 2,4,5-triaryl-1H-imidazoles and
bis(indolyl)methanes. The promising points for the presented protocols are efficiency, gen-
erality, high yields, short reaction times, cleaner reaction profile, simplicity, low cost, ease
of preparation and regeneration of the catalyst, and compliance with the green chemistry
protocols.
Experimental Section
All chemicals were purchased from Merck and Fluka Chemical Companies. All products
are known and were identified by comparison of their melting points and/or NMR data with
1
those reported in the literature. The H NMR (250 or 400 MHz) and 13C NMR (62.5 or
100 mhz) were run on a Bruker Avance DPX, FT-NMR spectrometer (δ in ppm). Melting
points were recorded on a Bu¨chi B-545 apparatus in open capillary tubes.
CAUTION: Chlorosulfonic acid is a toxic, volatile liquid which will cause very severe
burns; thus, the preparation of [Et3NSO3H]Cl from ClSO3H and Et3N must be carried out
very cautiously in an efficient hood cupboard.

Sulfonylimines, Imidazoles and bis(Indolyl)methanes
Preparation of Ionic Liquid [Et3NSO3H]Cl
217
A solution of triethylamine (1.01 g, 10 mmol) in CH2Cl2 (60 mL) was added dropwise to a
stirred solution (magnetic stirrer) of chlorosulfonic acid (1.17 g, 10 mmol) in dry CH2Cl2
(60 mL) over a period of 10 min at 10◦C. Afterward, the reaction mixture was allowed
to warm up to room temperature (accompanied with stirring), and stirred for another 4 h.
The solvent was evaporated, and the liquid residue was triturated with t-butyl methyl ether
(3 × 10 mL) and dried under high vacuum on a rotary evaporator (Heidolph, Laborota 4000)
using a vacuum pump (Platinum.JB.Aurora-IL 60507) at 90◦C to give [Et3NSO3H]Cl as a
pale viscous yellow oil in 93% yield.11
General Procedure for the Synthesis of N-Sulfonylimines 1a-n (Table 2)
To a mixture of sulfonamide (2 mmol) and carbonyl compound (2 mmol) in a 10 mL
round-bottomed flask fitted with a reflux condenser, was added [Et3N-SO3H]Cl (0.11 g,
0.5 mmol), and the resulting mixture was stirred in an oil-bath {80◦C (for compounds 1a-i)
or 100◦C (for compounds 1j-n)}. After completion of the reaction as monitored by TLC
(Merck silica gel 60 F254), the reaction mixture was cooled to room temperature; EtOAc
(30 mL) was added and it was stirred for 1 min. Then, the mixture was concentrated to 4 mL,
n-hexane (12 mL) was added, and the mixture was allowed to stand at room temperature
for 5–6 h. During this time, crystals of the product which had formed were collected on a
sintered glass funnel, washed with n-hexane, and dried.
General Procedure for the Preparation of 2,4,5-Triaryl-1H-imidazoles 2a-l (Table 3)
A mixture of benzil (0.42 g, 2 mmol), aldehyde (2.1 mmol), NH4OAc (0.62 g, 8 mmol)
and [Et3NSO3H]Cl (0.11 g, 0.5 mmol) in a 10 mL round-bottomed flask fitted with a reflux
condenser, was stirred in an oil-bath (100◦C). After completion of the reaction as monitored
with TLC (Merck silica gel 60 F254), the reaction mixture was cooled to room temperature,
H2O (20 mL) was added and it was stirred for 3 min, and filtered. The resulting solid (crude
product) was recrystallized from EtOAc to give the pure product.
General Procedure for the Synthesis of bis(Indolyl)methanes 3a-n (Table 4)
To a mixture of carbonyl compound (2 mmol) and [Et3NSO3H]Cl (0.11 g, 0.5 mmol) in
a mortar was added indole (4.1 mmol), and the resulting mixture was ground at room
temperature. After completion of the reaction as monitored by TLC (Merck silica gel 60
F254), EtOAc (40 mL) was added and the resulting solution was washed with saturated
solution of NaHCO3 (2 × 20 mL) and with saturated solution of NaHSO3 (2 × 30 mL).
The organic layer was separated and dried with CaCl2. The solvent was evaporated and the
crude product was purified by recrystallization from EtOAc/petroleum ether (1/2) or plate
chromatography on silica gel eluted with EtOAc/petroleum ether (1/2).
Acknowledgements
The authors gratefully acknowledge support of this work by the Research Affairs Office
of Payame Noor University and Bu-Ali Sina University (Grant number 32–1716 entitled
development of chemical methods, reagent and molecules).

218
Zare et al.
References
1. K. Mikami, “Green Reaction Media in Organic Synthesis”, Blackwell Publishing: Oxford, UK,
2005.
2. R. D. Rogers, “Ionic Liquids as Green Solvents: Progress and Prospects”, American Chemical
Society Publication: Washington, 2005.
3. P. Wasserscheid and T. Welton, “Ionic Liquids in Synthesis”, Wiley-VCH: Weinheim, 2003.
4. V. V. Namboodiri and R. S. Varma, Chem. Commun., 342 (2002).
5. A. R. Hajipour and M. Seddighi, Org. Prep. Proced. Int., 43, 292 (2011).
6. A. R. Hajipour and F. Rafiee, Org. Prep. Proced. Int., 42, 285 (2010).
7. H. R. Shaterian, M. Ranjbar and K. Azizi, J. Mol. Liq., 162, 95 (2011).
8. A. Hasaninejad, A. Zare, M. Shekouhy and J. Ameri Rad, J. Comb. Chem., 12, 844 (2010).
9. M. A. Zolfigol, A. Khazaei, A. R. Moosavi-Zare and A. Zare, Org. Prep. Proced. Int., 42, 95
(2010).
10. M. A. Zolfigol, A. Khazaei, A. R. Moosavi-Zare, A. Zare and V. Khakyzadeh, Appl. Catal. A:
Gen., 400, 70 (2011).
11. A. Zare, A. R. Moosavi-Zare, M. Merajoddin, M. A. Zolfigol, T. Hekmat-Zadeh, A. Hasaninejad,
A. Khazaei, M. Mokhlesi, V. Khakyzadeh, F. Derakhshan-Panah, M. H. Beyzavi, E. Rostami, A.
Arghoon and R. Roohandeh, J. Mol. Liq., 167, 69 (2012).
12. S. Kobayashi and H. Ishitani, Chem. Rev., 99, 1069 (1999).
13. H.-K. Yim and H. N. C. Wong, J. Org. Chem., 69, 2892 (2004).
14. H. Nisikori, R. Yoshihara and A. Hosomi, Synlett, 561 (2003).
15. D. L. Boger, W. L. Corbett, T. T. Curran and A. M. Kasper, J. Am. Chem. Soc., 113, 1713 (1991).
16. L. G. Arini, A. Sinclair, P. Szeto and R. A. Stockan, Tetrahedron Lett., 45, 1589 (2004).
17. X.-T. Zhou, Y.-R. Lin, L.-X. Dai, J. Sun, L.-J. Xia and M.-H. Tang, J. Org. Chem., 64, 1331
(1999).
18. A. Zare, A. Hasaninejad, M. Shekouhy and A. R. Moosavi Zare, Org. Prep. Proced. Int., 40, 457
(2008).
19. M. Hosseini-Sarvari, H. Sharghi and S. Ebrahimpourmoghaddam, ARKIVOC, xv, 255 (2007).
20. A. Zare, A. Hasaninejad, J. Sulfur Chem., 28, 357 (2007).
21. F. A. Davis, U. Nadir, E. W. Kluger, T. C. Sedergran, T. W. Panunto, R. Billmers, R. Jenkins, I.
J. Turchi, W. H. Watson, J. S. Chen and M. Kimura, J. Am. Chem. Soc., 102, 2000 (1980).
22. B. E. Love, P. S. Raje and T. C. Williams, Synlett, 493 (1994).
23. B. M. Trost and M. Christopher, J. Org. Chem., 56, 6468 (1991).
24. F. Bellina, S. Cauteruccio and R. Rossi, Tetrahedron, 63, 4571 (2007).
25. K. Hofmann, “Imidazole and Its Derivatives, Part I”, Inter Science Publishers, Inc., New York,
London, 1953.
26. S. Kantevari, C. K. S. Nair and M. Pardhasaradhi, J. Heterocycl. Chem., 43, 1353 (2006).
27. S. E. Wolkenberg, D. D. Wisnoski, W. H. Leister, Y. Wang, Z. Zhao and C. W. Lindsley, Org.
Lett., 6, 1453 (2004).

Sulfonylimines, Imidazoles and bis(Indolyl)methanes
219
28. A. M. M. Majalli and S. Sarshar, US Patent 5, 700, 826, 1997, 19 pp.; Chem. Abstr., 128, 88918a
(1998).
29. R. Schmierer, H. Mildenberger and H. Buerstell, German Patent 361464, 1987; Chem. Abstr.,
108, 37838 (1988).
30. A. H. Cook and D. G. Jones, J. Chem. Soc., 278 (1941).
31. S. E. Wolkenberg, D. D. Wisnoski, W. H. Leister, Y. Wang, Z. Zhao and C. W. Lindsley, Org.
Lett., 6, 1453 (2004).
32. A. R. Khosropour, Ultrason. Sonochem., 15, 659 (2008).
33. A. Shaabani and A. Rahmati, J. Mol. Catal. A: Chem., 249, 246 (2006).
34. M. M. Heravi, K. Bakhtiari, H. A. Oskooie and S. Taheri, J. Mol. Catal. A: Chem., 263, 279
(2007).
35. A. Parveen, M. R. S. Ahmed, K. A. Shaikh, S. P. Deshmukh and R. P. Pawar, ARKIVOC, xvi, 12
(2007).
36. S. Samai, G. C. Nandi, P. Singh and M. S. Singh, Tetrahedron, 65, 10155 (2009).
37. R. S. Joshi, P. G. Mandhane, M. U. Shaikh, R. P. Kale and C. H. Gill, Chin. Chem. Lett., 21, 429
(2010); Chem. Abstr. 152, 568068 (2010).
38. J. J. Michnovicz, H. L. Bradlow, M. J. Huang, T. Osawa, C. T. Ho and R. T. Rosen (editors),
“Food Phytochemicals for Cancer Prevention 1: Fruits and Vegetables”, American Chemical
Society: Washington, D. C., 1994.
39. A. Ramirez and S. Garcia-Rubio, Curr. Med. Chem., 10, 1891 (2003).
40. S. Zhao, X. Liao and J. M. Cook, Org. Lett., 4, 687 (2002).
41. M. Shiri, M. A. Zolfigol, H. G. Kruger and Z. Tanbakouchian, Chem. Rev., 110, 2250 (2010).
42. A. Hasaninejad, A. Zare, H. Sharghi, M. Shekouhy, R. Khalifeh, A. Salimi Beni and A. R.
Moosavi Zare, Can. J. Chem., 85, 416 (2007).
43. A. Hasaninejad, A. Zare, H. Sharghi, K. Niknam and M. Shekouhy, ARKIVOC, xiv, 39 (2007).