3-Methyl-1-sulfonic acid imidazolium chloride as a new, Efficient and recyclable catalyst and solvent for the preparation of N-sulfonyl imines at room Temperature

Article abstract of DOI:10.1007/BF03246053

New Bronsted acidic ionic liquid, 3-methyl-1-sulfonic acid imidazolium chloride {[Msim]Cl} was used as an efficient, green and reusable catalyst and solvent for the synthesis of N-sulfonyl imines via the condensation of sulfonamides with aldehydes as well

Full text of DOI:10.1007/BF03246053

J. Iran. Chem. Soc., Vol. 7, No. 3, September 2010, pp. 646-651.
JOUIRrNaAnLiaOnF THE
Chemical Society
3-Methyl-1-Sulfonic Acid Imidazolium Chloride as a New, Efficient and Recyclable
Catalyst and Solvent for the Preparation of N-Sulfonyl Imines at Room Temperature
M.A. Zolfigola,*, A. Khazaeia,*, A.R. Moosavi-Zarea and A. Zareb
aFaculty of Chemistry, Bu-Ali Sina University, Hamedan, 6517838683, Iran
bDepartment of Chemistry, Payame Noor University (PNU), Iran
(Received 9 August 2009, Accepted 11 September 2009)
New Brønsted acidic ionic liquid, 3-methyl-1-sulfonic acid imidazolium chloride {[Msim]Cl} was used as an efficient, green
and reusable catalyst and solvent for the synthesis of N-sulfonyl imines via the condensation of sulfonamides with aldehydes as
well as isatin. The reactions proceeded at room temperature and the title compounds were obtained in high to excellent yields and
in relatively short reaction times.
Keywords: Brønsted acidic ionic liquid, 3-Methyl-1-sulfonic acid imidazolium chloride {[Msim]Cl}, N-Sulfonyl imine,
Sulfonamide, Aldehyde
INTRODUCTION
CH2Cl2
r.t.
+
Cl
+
ClSO3H
N
N
N
N
SO3H
Ionic liquids are the subject of considerable current interest
as benign reaction media in organic synthesis because of their
unique properties such as non-volatility, non-flammability,
safety, recyclability and ability to dissolve a wide range of
materials [1]. During the past decade, a variety of ionic liquids
have been demonstrated as efficient and practical alternatives
to organic solvents for many important organic
transformations [1]. These green solvents have also been used
as catalysts in various organic reactions [2]. As part of our
ongoing research to extend the application of acidic catalysts
and reagents in organic synthesis [3], we have synthesized 3-
methyl-1-sulfonic acid imidazolium chloride {[Msim]Cl}as a
new Brønsted acidic ionic liquid, from the reaction of 1-
methylimidazole with chlorosulfonic acid at room temperature
(Scheme 1). We believe that this novel ionic liquid can be
Scheme 1
applied as a catalyst as well as solvent for different organic
transformations. We found out that the synthesis of N-sulfonyl
imines from sulfonamides and carbonyl compounds can be
efficiently achieved in [Msim]Cl. This is the first report of the
application of this novel ionic liquid in organic synthesis.
Imines bearing electron-withdrawing N-substituents are
useful intermediates in organic synthesis [4]. Among them, N-
sulfonyl imines are the center of attention for organic chemists
because the sulfonyl moiety has proven to be a powerful
activating group of the C=N bond in these compounds. As a
consequence, N-sulfonyl imines have been widely used in
organic synthesis [5]. Furthermore, they are excellent
substrates in nucleophilic additions [6], reductions [7], aza
Diels-Alder reactions [8], aziridine [9] and oxaziridine
*Corresponding author. E-mail: mzolfigol@yahoo.com;
khazaei_1326@yahoo.com

Zolfigol et al.
O
S
O
O
S
O
[Msim]Cl
synthesis [10], as well as ene reactions [11]. Several routes
+
X
NH2
Ar CHO
X
N
r.t. 10-60 min
toward the synthesis of N-sulfonyl imines have been
developed via Lewis and Brønsted acid catalyzed reactions of
sulfonamides with aldehyde precursors [12], rearrangement of
oxime o-sulfinates [13], tellurium mediated reaction of
aldehydes with chloramines T by utilization of the in situ
generated N,N'-ditosyltellurodiimide [14], application of N-
sulfinyl sulfonamides instead of sulfonamides to generate
sulfonyl imine in situ via a [2+2] cycloaddition and extrusion
of sulfur dioxide [15], generation of sulfonamidosulfones and
basic elimination [16], and catalyzed isomerization or
rearrangement of N-sulfonyl aziridines [17]. However, most of
the reported methods suffer from drawbacks like long reaction
times, unsatisfactory yields, harsh conditions, the use of
expensive reagents, the use of multi-steps and cumbersome
procedures, and no agreement with the green chemistry
protocols. Moreover, it is worth noting that the preparation of
N-sulfonyl imines under mild reaction conditions has been
scarcely reported in the literature [12f,i]. Therefore,
development of an efficient, one-step, mild and
environmentally friendly procedure for the synthesis of N-
sulfonyl imines is in order.
Ar
78-96%
X = Me, H
Scheme 2
O
O
S
O
O
S
O
[Msim]Cl
NH2
+
O
N
O
r.t., 40 min
N
H
NH
89%
Scheme 3
methylimidazole (0.410 g, 5 mmol) in dry CH2Cl2 (50 ml), and
then chlorosulfonic acid (0.605 g, 5.2 mmol) was added
dropwise over a period of 5 min at room temperature. After
the addition was completed, the reaction mixture was stirred
for 20 min, halted for 5 min, and the CH2Cl2 was decanted.
The residue was washed with dry CH2Cl2 (3 ꢀ 50 ml) and
dried under vacuum to give [Msim]Cl as a viscous colorless
oil in 92% yield, 0.912 g.
Considering the above mentioned routs for the synthesis in
question, herein we report a new procedure in which an
imidazolium salt as an ionic liquid has been used as a
recyclable catalyst and media for the preparation of N-sulfonyl
imines at room temperature (Schemes 2 and 3).
General Procedure for the Preparation of N-Sulfonyl
Imines and Recycling of [Msim]Cl
To a mixture of compounds consisting of sulfonamide (2
mmol) and carbonyl compound (2 mmol) in a round-bottomed
flask (10 ml) was added [Msim]Cl (0.792 g, 4 mmol). The
resulting mixture was stirred at room temperature for the
appropriate time (Table 2). Afterward, the reaction mixture
was extracted with dry ethyl acetate (2 × 20 ml) and the
organic extracts were combined. The mixture was
concentrated to 4 ml, and n-hexane (12 ml) was added to the
mixture and was allowed to stand at room temperature for 5-6
h. The target molecules were collected by filtration, washed
with n-hexane and dried. The remaining ionic liquid was dried
and used for the next run under identical reaction conditions.
EXPERIMENTAL
Chemical and Apparatus
All chemicals were purchased from Merck or Fluka
Chemical Companies. All compounds were identified by
comparison of their melting points and/or NMR data with
1
those reported for the authentic samples. The H NMR (250
MHz) and 13C NMR (62.9 MHz) were run on a Bruker Avance
DPX-250, FT-NMR spectrometer (ꢀ in ppm). Microanalyses
were performed on a Perkin-Elmer 240-B microanalyzer.
Melting points were recorded on a Büchi B-545 apparatus in
open capillary tubes.
Spectral Data of [Msim]Cl
1
Viscous colorless oil; H NMR (DMSO-d6): ꢀ (ppm) 3.77
(s, 3H, CH3), 7.46 (s, 1H), 7.51 (s, 1H), 8.84 (s, 1H), 13.96 (s,
1H); 13C NMR (DMSO-d6): ꢀ 36.5, 120.6, 124.2, 138.6; Anal.
Calcd. for C4H7ClN2O3S: C, 24.19; H, 3.55; N, 14.10. Found:
Preparation of Ionic Liquid [Msim]Cl
A round-bottomed flask (100 ml) was charged with 1-
647

3-Methyl-1-Sulfonic Acid Imidazolium Chloride
C, 24.41; H, 3.69; N, 13.92.
Table 1. The Condensation of 4-Methylbenzenesulfonamide
with Benzaldehyde in Different Brønsted Acidic
Ionic Liquids at Room Temperature
Selected Physical and Spectral Data of the Products
(E)-N-Benzylidenebenzenesulfonamide (Table 2, entry
2). White solid; m.p.: 76-78 °C (Lit. [12j] m.p.: 76-78 °C); 1H
NMR (CDCl3): ꢀ 7.61 (m, 6H), 8.02 (m, 4H), 9.05 (s, 1H); 13C
NMR (CDCl3): ꢀ 127.1, 128.3, 129.5, 130.3, 131.7, 132.8,
134.0, 136.1.0, 171.2.
Entry
1b
Ionic liquid
[Msim]Cl
Time (min) Yield (%)a
30
70
90
90
90
90
92
68
56
61
49
57
2
[Hmim]HSO4
[Hmim]Tfa
[Hmim]OTS
[Hmim]BF4
[Bmim]HSO4
(E)-N-(2-Oxoindolin-3-ylidene)benzenesulfonamide
(Table 2, entry 15). Orange solid; m.p.: 144-145 °C (Lit. [12j]
3c
4
1
m.p.: 143-144 °C); H NMR (DMSO-d6): ꢀ 6.89 (m, 1H), 7.05
(m, 1H), 7.34 (m, 2H), 7.48 (m, 1H), 7.56 (m, 2H), 7.84 (m,
2H), 11.00 (s, 1H); 13C NMR (DMSO-d6): ꢀ 112.2, 117.8,
122.7, 124.6, 125.5, 128.8, 131.7, 138.3, 144.1, 150.7, 159.3,
184.3.
5
6
aIsolated pure product.
RESULTS AND DISCUSSION
withdrawing substituents and halogens increased the reaction
yields (Table 2, entries 3 and 4 as well as 8-11); however,
electron-releasing substituents slightly decreased the yields
(Table 2, entries 5, 6 and 7). Moreover, the condensation of
sulfonamides with dicarbonyl compounds as well as isatin can
be powerfully carried out using [Msim]Cl as the catalyst and
solvent (Scheme 2 and Table 2, entries 12 and 15).
In another study, the efficiency and applicability of this
new catalyst was compared with some reported catalysts for
the preparation of N-sulfonyl imines (Table 3). As is shown in
Table 3, [Msim]Cl afforded the products in higher yields and
in extremely milder reaction conditions.
Ease of recycling is a desirable feature of ionic liquids. It
must be mentioned that [Msim]Cl was partially hydrolyzed
during the reaction without loss of its reusability. For the
reaction 4-methylbenzenesulfonamide with benzaldehyde
(model reaction), no significant loss of the product yield was
observed when the ionic liquid was used after three times
recycling (see Table 4).
In order to optimize the reaction conditions, the
condensation of 4-methylbenzenesulfonamide (2 mmol) with
benzaldehyde (2 mmol) was selected as a model reaction in
the presence of [Msim]Cl (4 mmol) as the catalyst and solvent
at room temperature (Scheme 1). Interestingly, the catalytic
activity of the ionic liquid was excellent and the product was
produced in 92% yield after 30 min. To evaluate the efficiency
and the capacity of [Msim]Cl in comparison with the reported
Brønsted acidic ionic liquids, the model reaction was tested in
some of these ionic liquids, including [Hmim]HSO4,
[Hmim]Tfa, [Hmim]OTs, [Hmim]BF4 and [Bmim]HSO4. The
results are summarized in Table 1. As can be seen from Table
1, [Msim]Cl afforded the product in higher yield and shorter
reaction time.
Afterward, 4-methylbenzenesulfonamide and benzene-
sulfonamide were condensed with various aldehydes as well as
with isatin in order to assess the applicability and scope of the
catalyst; the respective results are displayed in Table 2. As
Table 2 indicates, all reactions proceeded efficiently in the
presence of [Msim]Cl at room temperature and the N-sulfonyl
imines were produced in high to excellent yields in relatively
short reaction times. In this study, the influence of electron-
withdrawing substituents, electron-releasing substituents and
halogens on the aromatic ring of aldehydes upon results of the
reaction was investigated. The results showed that electron-
CONCLUSIONS
In summary, we have introduced ionic liquid, 3-methyl-1-
sulfonic acid imidazolium chloride, as a novel, efficient and
reusable catalyst and solvent in organic synthesis. In this
work, this acidic ionic liquid has been used successfully as the
648

Zolfigol et al.
Table 2. Preparation of N-Sulfonyl Imines from Sulfonamides and Aldehydes as well as Isatin in [Msim]Cl
at Room Temperature
Carbonyl
compound
Entry
Product
Time (min)
Yield (%)a
O
Me
S
O
N
CHO
1
2
3
4
5
6
30
30
10
10
30
30
92
90
96
95
89
87
O
S
O
N
N
CHO
O
S
O
Me
Me
O2N
CHO
CHO
CHO
CHO
NO2
O
S
O
N
O2N
Me
NO2
O
S
O
N
Me
O
S
O
N
Me
Me
OMe
O
S
O
OMe
Me
N
CHO
7
50
86
MeO
MeO
Cl
O
S
O
Me
N
CHO
CHO
8
20
20
20
25
60
95
92
94
95
78
Cl
O
S
O
N
Cl
9
Cl
O
S
O
Cl
Cl
Cl
Me
N
10
11
12b
CHO
O
S
O
Cl
N
CHO
O
S
O
Me
N
OHC
CHO
CHO
O
S
O
N
CHO
13
14
30
15
91
93
O
S
O
Me
N
CHO
O
S
S
O
S
O
N
O
15
40
89
O
NH
N
H
aIsolated pure product. bIn this reaction, bis-N-sulfonyl imine was obtained in very low yield.
649

3-Methyl-1-Sulfonic Acid Imidazolium Chloride
Table 3. The Comparative Condensation of 4-Methylbenzenesulfonamide with Benzaldehyde Using the
Reported Catalysts vs. [Msim]Cl
Entry
Reagent and conditions
Time (min)
Yield (%)
Ref.
-
1
2
3
4
5
6
7
8
9
[Msim]Cl , r.t.
30
6
92
69
75
68
58
85
91
85
80
CaCO3, K10 Clay, CH(OMe)3, Microwave
Silica chloride, solvent-free, 120 °C
Si(OEt)4, 160 °C
[5a]
180
360
25
[12a]
[12b]
[12c]
[12g]
[12h]
[12i]
[12k]
TiCl4, NEt3, 0 °C, CH2Cl2
Silphox (1 g), 110 °C
180
120
45
P2O5/SiO2, solvent-free, 110 °C
Ph(p-MeOC6H4)2Cl, MeCN, 40 °C
MgO, Microwave, 110 °C
12
Table 4. The Reaction of 4-Methylbenzenesulfonamide with
Benzaldehyde in the Presence of Recycled
[Msim]Cl at Room Temperature
Hamedan, I.R. Iran.
REFERENCES
[1]
a) R.D. Rogers, Ionic Liquids as Green Solvents:
Progress and Prospect, American Chemical Society
Publication, 2005; b) K. Mikami, Green Reaction
Media in Organic Synthesis; Blackwell Publishing, UK,
Oxford, 2005; c) P. Wasserscheid, T. Welton, Ionic
Liquids in Synthesis; Wiley-VCH, Weinheim, 2003; d)
A. Zare, A. Hasaninejad, A.R. Moosavi Zare, A.
Parhami, H. Sharghi, A. Khalafi-Nezhad, Can. J. Chem.
85 (2007) 438; e) A. Zare, A. Hasaninejad, A. Khalafi-
Nezhad, A.R. Moosavi Zare, A. Parhami, ARKIVOC
xiii (2007) 105; f) M. Dabiri, P. Salehi, M.
Baghbanzadeh, M. Shakouri, S. Otokesh, T. Ekrami, R.
Doosti, J. Iran. Chem. Soc. 4 (2007) 393; g) M.M.
Mojtahedi, M.S. Abaee, H. Abbasi, J. Iran. Chem. Soc.
3 (2006) 93; h) A. Sharifi, M.S. Abaee, M. Mirzaei, R.
Salimi, J. Iran. Chem. Soc. 5 (2008) 135; i) M.M.
Khodaei, A.R. Khosropour, S. Ghaderi, J. Iran. Chem.
Soc. 3 (2006) 69; j) A. Zare, A. Hasaninejad, A.
Khalafi-Nezhad, A.R. Moosavi-Zare, M.H. Beyzavi, F.
Khedri, F. Asadi, N. Hayati and A. Asifi, J. Iran. Chem.
Entry
Cycle
1st run
2nd run
3rd run
4th run
Time (min)
Yield (%)
1
2
3
4
30
30
33
37
92
91
90
88
aIsolated pure product.
catalyst and solvent for the efficient synthesis of N-sulfonyl
imines via the condensation of sulfonamides with aldehydes as
well as isatin at room temperature.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge the partial support of
this work by the Research Affairs Office of Bu-Ali Sina
University (Grant number 32-1716 entitled development of
chemical methods, reagent and molecules.), and Center of
Excellence in Development of Chemical Methods (CEDCM),
650

Zolfigol et al.
Soc. 7 (2010) 461; k) A.R. Khosropour, M.M. Khodaei,
Tetrahedron Lett. 45 (2004) 1589.
S. Ghaderi, J. Iran. Chem. Soc. 5 (2008) 407.
[10] X.-T. Zhou, Y.-R. Lin, L.-X. Dai, J. Sun, L.-J. Xia, M.-
H. Tang, J. Org. Chem. 64 (1999) 1331.
[11] M.J. Melnick, S.M. Weinreb, A. Freyer, Tetrahedron
Lett. 29 (1988) 3891.
[12] a) A. Hasaninejad, H. Sharghi, Phosphorus, Sulfur and
Silicon 182 (2007) 873; b) B.E. Love, P.S. Raje, T.C.
Williams, Synlett (1994) 493; c) W.B. Jennings, C.J.
Lovely, Tetrahedron 47 (1991) 5561; d) F.A. Davis,
J.M. Kaminski, E.W. Kluger, H.S. Freilich, J. Am.
Chem. Soc. 97 (1975) 7085; e) 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, M. Kimura, J. Am. Chem. Soc. 102 (1980) 2000;
[2]
a) A. Zare, A. Parhami, A.R. Moosavi-Zare, A.
Hasaninejad, A. Khalafi-Nezhad, M.H. Beyzavi, Can. J.
Chem. 87 (2009) 416; b) A. Zare, A.R. Moosavi-Zare,
A. Hasaninejad, A. Parhami, A. Khalafi-Nezhad, M.H.
Beyzavi, Synth. Commun. 39 (2009) 3156; c) J.R.
Harjani, S.J. Nara, M.M. Salunkhe, Tetrahedron Lett.
43 (2002) 1127; d) V.V. Namboodiri, R.S. Varma,
Chem. Commun. (2002) 342; e) V.R. Koch, L.L.
Miller, R.A. Osteryoung, J. Am. Chem. Soc. 98 (1976)
5277; f) M. Dabiri, P. Salehi, M. Baghbanzadeh, M.
Shakouri, S. Otokesh, T. Ekrami, R. Doosti, J. Iran.
Chem. Soc. 4 (2007) 393; g) G. Zhao, T. Jiang, H. Gao,
B. Han, J. Huang, D. Sun, Green Chem. 6 (2004) 75; h)
C.J. Adams, M.J. Earle, G. Roberts, K.R. Seddon,
Chem. Commun. (1998) 2097; i) H.-P. Zhu, F. Yang, J.
Tang, M.-Y. He, Green Chem. 5 (2003) 38; j) H. Tajik,
K. Niknam, F. Parsa, J. Iran. Chem. Soc. 6 (2009) 159;
k) R.S. Bhosale, S.R. Sarda, R.P. Giram, D.S. Raut,
S.P. Parwe, S.S. Ardhapure, R.P. Pawar, J. Iran. Chem.
Soc. 6 (2009) 519; l) A. Shaabani, R. Ghaderi, A.
Rahmati, A.H. Rezayan, J. Iran. Chem. Soc. 6 (2009)
710.
f)
M.
Hosseini-Sarvari,
H.
Sharghi,
S.
Ebrahimpourmoghaddam, ARKIVOC xv (2007) 255;
g) A. Hasaninejad, A. Zare, J. Sulfur Chem. 28 (2007)
357; h) A. Hasaninejad, A. Zare, H. Sharghi, M.
Shekouhy, ARKIVOC xi (2008) 64; i) A. Khalafi-
Nezhad, A. Parhami, A. Zare, A. Nasrolahi Shirazi,
A.R. Moosavi Zare, A. Hasaninejad, Can. J. Chem. 86
(2008) 456; j) A. Zare, A. Hasaninejad, M. Shekouhy,
A.R. Moosavi Zare, Org. Prep. Proced. Int. 40 (2008)
457; k) A. Hasaninejad, A. Zare, A.R. Moosavi Zare, A.
Parhami, H. Sharghi, A. Khalafi-Nezhad, Phosphorus,
Sulfur and Silicon 183 (2008) 2769.
[3]
For reviews see; a) P. Salehi, M.A. Zolfigol, F. Shirini,
M. Baghbanzadeh. Curr. Org. Chem. 10 (2006) 2171),
b) F. Shirini, M.A. Zolfigol, P. Salehi, M. Abedini,
Curr. Org. Chem. 12 (2008) 183.
[13] D.L. Borger, W.L. Corbett, J. Org. Chem. 57 (1992)
4777.
[4]
[5]
a) R. Bloch, Chem. Rev. 98 (1998) 1407; b) H. Miyabe,
M. Ueda, T. Naito, Synlett (2004) 1140; c) S.
Kobayashi, H. Ishitani, Chem. Rev. 99 (1999) 1069.
a) A. Vass, J. Dudas, R.S. Varma, Tetrahedron Lett. 40
(1999) 4951; b) S.M. Weinreb, Top. Curr. Chem. 190
(1997) 131; c) M. Gohain, Synlett (2003) 2097; d) D.
Enders, U. Reinhold, Tetrahedron: Asymmetr. (1997)
1895.
H.-K. Yim, H.N.C. Wong, J. Org. Chem. 69 (2004)
2892.
H. Nisikori, R. Yoshihara, A. Hosomi, Synlett (2003)
561.
[14] B.M. Trost, C. Marrs, J. Org. Chem. 56 (1991) 6468.
[15] a) R. Albrecht, G. Kresze, Chem. Ber. 97 (1964) 483;
b) R. Albrecht, G. Kresze, Chem. Ber. 98 (1965) 1431;
c) M.J. Melnick, A.J. Freyer, S.M. Weinreb,
Tetrahedron Lett. 29 (1988) 3891; d) A.K. McFarlane,
G. Thomas, A. Whiting, Tetrahedron Lett. 34 (1993)
2379.
[16] a) A.M. Kanazawa, J.-N. Denis, A.E. Greene, J. Org.
Chem. 59 (1994) 1238; b) J. Sisko, M. Mellinger, P.W.
Sheldrake, N.H. Baine, Tetrahedron Lett. 37 (1996)
8113; c) F. Chemla, V. Hebbe, J.-F. Normant, Synthesis
(2000) 75; d) Z. Li, X. Ren, P. Wei, H. Wan, Y. Shi, P.
Ouyang, Green Chem. 8 (2006) 433.
[6]
[7]
[8]
[9]
D.L. Boger, W.L. Corbett, T.T. Curran, A.M. Kasper, J.
Am. Chem. Soc. 113 (1991) 1713.
L.G. Arini, A. Sinclair, P. Szeto, R.A. Stockan,
[17] J.P. Wolfe, J.E. Ney, Org. Lett. (2003) 4607.
651