Green, Catalyst-Free Protocol for the Efficient Synthesis of N-Sulfonyl Aldimines and Ketimines in Ionic Liquid [Bmim]Br

Article abstract of DOI:10.1080/00397910902731000

Sulfonamides are efficiently condensed with aldehydes as well as ketones in the absence of catalyst in 1-butyl-3-methylimidazolium bromide ([bmim]Br) under microwave irradiation to afford N-sulfonyl aldimines and ketimines in good to excellent yields in s

Full text of DOI:10.1080/00397910902731000

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Green, Catalyst-Free Protocol
for the Efficient Synthesis
of N-Sulfonyl Aldimines and
Ketimines in Ionic Liquid
[Bmim]Br
Abdolkarim Zare a , Ahmad Reza Moosavi-Zare a
, Alireza Hasaninejad a , Abolfath Parhami a , Ali
Khalafi-Nezhad c & Mohammad Hassan Beyzavi c
a Department of Chemistry, Payame Noor University
(PNU), Iran
b Department of Chemistry, Faculty of Sciences,
Persian Gulf University, Bushehr, Iran
c Department of Chemistry, College of Sciences,
Shiraz University, Shiraz, Iran
Version of record first published: 03 Aug 2009.
To cite this article: Abdolkarim Zare , Ahmad Reza Moosavi-Zare , Alireza
Hasaninejad , Abolfath Parhami , Ali Khalafi-Nezhad & Mohammad Hassan Beyzavi
(2009): Green, Catalyst-Free Protocol for the Efficient Synthesis of N-Sulfonyl
Aldimines and Ketimines in Ionic Liquid [Bmim]Br, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 39:17,
3156-3165
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Synthetic Communications1, 39: 3156–3165, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910902731000
Green, Catalyst-Free Protocol for the Efficient
Synthesis of N-Sulfonyl Aldimines and Ketimines
in Ionic Liquid [Bmim]Br
Abdolkarim Zare,1 Ahmad Reza Moosavi-Zare,1
Alireza Hasaninejad,1 Abolfath Parhami,1 Ali Khalafi-Nezhad,3 and
Mohammad Hassan Beyzavi3
1Department of Chemistry, Payame Noor University (PNU), Iran
2Department of Chemistry, Faculty of Sciences, Persian Gulf University,
Bushehr, Iran
3Department of Chemistry, College of Sciences,
Shiraz University, Shiraz, Iran
Abstract: Sulfonamides are efficiently condensed with aldehydes as well as
ketones in the absence of catalyst in 1-butyl-3-methylimidazolium bromide
([bmim]Br) under microwave irradiation to afford N-sulfonyl aldimines and
ketimines in good to excellent yields in short reaction times.
Keywords: Catalyst-free, ionic liquid, microwave, N-sulfonyl aldimine, N-sulfonyl
ketimine, sulfonamide
In recent years, catalyst-free reactions have attracted increasing interest
because of the ease of experimental procedure as well as workup, low
cost, possibility of using acid- or base-sensitive substrates, and environ-
mentally benign process.[1] This useful technique has been used in several
organic transformations, such as synthesis of benzoic esters and benzyl
esters,[1a] regioselective conversion of epoxides to vicinal halohydrins,[1b]
Received December 7, 2008.
Address correspondence to Abdolkarim Zare, Department of Chemistry,
Payame Noor University (PNU), Bushehr 1698, Iran. E-mail: abdolkarimzare@
yahoo.com or Alireza Hasaninejad, Department of Chemistry, Faculty of Sciences,
Persian Gulf University, Bushehr 75169, Iran. E-mail: ahassaninejad@yahoo.com
3156

Synthesis of N-Sulfonyl Imines
3157
synthesis of dithiocarbamates,[1c] synthesis of 2-aminothiazoles,[1d]
transesterification of triglycerides,[1e] N-benzyloxycarbonylation of
amines,[1f] synthesis of polyorganosiloxanes,[1g] gem-bisallylation of
carboxylic acid derivatives,[1h] and Michael-type addition of amines to
electron-deficient alkenes.[1i] As a continuation of our interest in develop-
ing the efficient synthetic methodologies in organic synthesis,[2] we have
initiated a program to study useful organic transformations in the
absence of catalyst. Herein, we found that the synthesis of N-sulfonyl
imines from sulfonamides and carbonyl compounds can be efficiently
achieved without catalyst in [bmim]Br under microwave irradiation.
Currently, ionic liquids are the subject of considerable interest as
benign reaction media in organic synthesis because of their unique prop-
erties, such as nonvolatility, nonflammability, recyclability, high thermal
stability, and ability to dissolve a wide range of materials. During the past
decade, a variety of ionic liquids have been demonstrated as efficient and
practical alternatives to volatile organic solvents for many important
organic reactions, including carbon–carbon, carbon–oxygen, carbon–
sulfur, carbon–nitrogen, and carbon–phosphorus bond formation.[3]
Together with the substitution of common molecular solvents, non-
conventional activation methods, mainly microwave irradiation, have
appeared as powerful techniques to decrease reaction times and to
enhance reaction rates.[4]
The preparation of N-sulfonyl imines has attracted much attention
in recent years for the versatile usage of the C ¼ N bond in organic
synthesis.[5–13] For example, they are excellent substrates in nucleophilic
additions,[6] reductions,[7] cycloadditions,[8] aza-Henry reactions,[9] aza
Diels–Alder reactions,[10] aziridine,[11] and oxaziridine synthesis,[12] as
well as ene reactions.[13] Several synthetic methods for the preparation
of N-sulfonyl imines have been reported in the literature.[14–16] Most of
them involve the condensation of sulfonamides with aldehydes or ketones
in the presence of a strong Lewis or protic acid.[15] In many cases,
strongly acidic conditions are not compatible with other functionalities
present in a given substrate. Some methods need two-step procedures,
are expensive methods, or generate toxic by-products. Several methods
also require the preparation of starting materials such as oxime, sulfiny-
limine, and=or aziridine. Moreover, most of the reported methods are not
efficient for the synthesis of aliphatic N-sulfonyl aldimines or N-sulfonyl
ketimines. Unsatisfactory yields and long reaction times are also disad-
vantages of some methods. Moreover, recently we have introduced some
new methods for the synthesis of N-sulfonyl imines via the condensation
of sulfonamides with carbonyl compounds.[16] However, these methods
are associated with one or more of the following disadvantages: (i) non-
recyclability of the catalyst, (ii) moderate yield, (iii) no agreement with

3158
A. Zare et al.
Scheme 1. Condensation of benzenesulfonamide with benzaldehyde.
the green chemistry protocols by the use of volatile organic solvents, and
(iv) inefficiency of the procedure when ketones instead of aldehydes are
applied in the reaction. Furthermore, there is no catalyst-free protocol
for the synthesis of N-sulfonyl imines in the literature. Because of the lim-
itations of the reported methods, development of an efficient, general,
rapid, and catalyst-free protocol for the synthesis of N-sulfonyl imines
under neutral conditions in one step would be desirable. To reach this
goal, in this work we report a new method for the synthesis of N-sulfonyl
aldimines and ketimines via the catalyst-free condensation of sulfona-
mide with aldehydes as well as ketones in [bmim]Br as a relatively neutral
ionic liquid under microwave irradiation (Scheme 1). To the best of our
knowledge, this is the first catalyst-free protocol for the synthesis of
N-sulfonyl imines. It is also important to note that this presented work
has none of the previously mentioned drawbacks.
At first, we examined the condensation of benzenesulfonamide
(1 mmol) with benzaldehyde (1 mmol) without catalyst under solvent-free
and microwave conditions at 400 W of microwave power but these
conditions afforded the corresponding N-sulfonyl imine in trace yield
after 20 min (Scheme 1, Table 1). Increasing the reaction time or the
microwave power did not improve the yield. The yield increased to
96% when the reaction was performed in [bmim]Br (0.25 g) at 400 W
(max. 110ꢀC) (Table 1). The reaction was also checked in [bmim]Cl
and [bmim]I (Table 1). As Table 1 indicates, [bmim]Br gave the best
results. In another study, the reaction of benzenesulfonamide with
Table 1. Catalyst-free condensation of benzenesulfonamide with benzaldehyde
under solvent-free conditions as well as in ionic liquids promoted by microwave
irradiation (400 W, max. 110ꢀC)
Entry
Solvent
Time (min)
Yielda (%)
1
2
3
4
Solvent-free
[bmim]Br
[bmim]Cl
[bmim]I
20
12
12
12
Trace
96
78
67
aIsolated yield.

Synthesis of N-Sulfonyl Imines
3159
benzaldehyde in [bmim]Br was tested at different microwave powers
(100–600 W) at range of 100–140ꢀC. The reasonable results were obtained
at 400 W and 110ꢀC.
After optimization of the reaction conditions, sulfonamides were
reacted with structurally diverse aromatic and aliphatic aldehydes as well
as ketones to recognize the efficiency and the scope of the catalyst-free
procedure. The results are displayed in Table 2. As can be seen from
Table 2, all reactions proceeded efficiently, and the desired products were
produced in good to excellent yields and in short reaction times. It must
Table 2. Catalyst-free synthesis of N-sulfonyl imines in [bmim]Br under
microwave irradiation (400 W, max. 110ꢀC)
Time Yielda
(min) (%)
MpꢀC
(lit[Ref].)
Entry
X
R
R’
1
2
3
4
5
6
7
8
H
H
H
H
H
H
H
H
C6H5
H
12
16
16
19
18
17
17
17
96
92
91
85
73
87
85
88
76–78 (76–78[16a]
)
p-CH3C6H4
m-CH3C6H4
p-N(CH3)2C6H4
p-NO2C6H4
p-BrC6H4
H
H
H
H
H
H
H
114–116 (116–118[15a]
)
87–89 (85–88[15b]
)
206–207 (206–207[16b]
)
)
)
163–164 (164–165[16a]
205–207 (205–207[16a]
p-ClC6H4
m-ClC6H4
131–133 (127–130[15a])
97–99 (92–94[15b]
)
9
20
81
(144–145)
10
11
12
13
14
15
16
17
18b
CH3 C6H5
H
H
H
H
H
H
H
H
CH3
12
15
18
18
18
16
15
18
25
97
95
96
69
74
83
91
76
54
109–110 (108[16d]
)
CH3 p-(isopropyl)C6H4
CH3 p-OCH3C6H4
CH3 p-NO2C6H4
CH3 p-CNC6H4
CH3 p-ClC6H4
CH3 2-Furyl
109–111 (110–112[16a]
127–129 (128–129[14a]
163–164 (164–166[16a]
)
)
)
)
)
172–173 (172–173[16d]
168–169 (172–173[14a]
99–100 (101[14a]
136–137 (138[17]
84–86 (88–89[14b]
)
CH3 CH3(CH2)5CH2
CH3 C6H5
)
)
aIsolated yield.
bThis reaction was carried out at 130ꢀC.

3160
A. Zare et al.
be mentioned that the presence of electron-releasing substituents CH3
and OCH3 on the aromatic ring of aldehydes had no significant effect
on the reaction yields (Table 2, entries 2, 3, 11, and 12); however,
N(CH3)2 and halogens slightly decreased the yields (Table 2, entries 4,
6–8, and 15). Electron-withdrawing substituents also decreased the yields
(Table 2, entries 5, 13, and 14). Interestingly, the catalyst-free method was
successfully applied for the reaction of sulfonamides with aliphatic
aldehydes as well as ketones (Table 2, entries 9, 17, and 18). However,
most of the reported methods are not efficient when aliphatic aldehydes
or ketones are used in the reaction.
One of the most interesting properties of ionic liquids is their ease of
recycling. For the reaction of benzenesulfonamide with benzaldehyde, no
significant loss of the product yield was observed when [bmim]Br was
reused even after three times.
In summary, we have reported the first catalyst-free method for the
condensation of sulfonamides with aldehydes as well as ketones. The pro-
mising points for the presented methodology are efficiency, generality,
good yield, short reaction time, low cost, cleaner reaction profile, ease
of product isolation, simplicity, potential for recycling of the solvent,
and finally agreement with the green chemistry protocols, which makes
it a useful and attractive process for the synthesis of N-sulfonyl aldimines
and ketimines.
EXPERIMENTAL
All chemicals were purchased from Merck or Fluka Chemical Compa-
nies. The ionic liquid was prepared according to the reported methods.[18]
All reactions were carried out using a laboratory microwave oven
1
(MicroSYNTH, Milestone Company, Italy). The H NMR (250 MHz)
and 13C NMR (62.5 MHz) spectra were run on a Bruker Avance
DPX-250, FT-NMR spectrometer, d in parts per million (ppm). Mass
spectra (MS) were recorded on a Shimadzu GC MS-QP 1000 EX appa-
ratus. Microanalyses were performed on a Perkin-Elmer 240-B microana-
lyzer. Melting points were recorded on a Buchi B-545 apparatus in open
¨
capillary tubes.
General Procedure for the Catalyst-Free Synthesis of N-Sulfonyl Imines
[bmim]Br (0.25 g) was added to a mixture of sulfonamide (1 mmol) and
carbonyl compound (1 mmol) in a microwave vessel and mixed carefully
with a small rod. The resulting mixture was irradiated in a microwave

Synthesis of N-Sulfonyl Imines
3161
oven at 400 W for the appropriate time (Table 2). The microwave was
programmed to give a maximum internal temperature of 110ꢀC. After-
ward, the reaction mixture was cooled to room temperature and was
extracted with Et2O (3 ꢁ 15 mL). The organic extracts were then
combined and washed with saturated solution of NaHSO3 (2 ꢁ 20 mL).
The organic layer was separated and dried with CaCl2. The solvent
was evaporated, and the crude product was dissolved in warm ethyl
acetate (2 mL), treated with n-hexane (6 mL), and allowed to stand at
room temperature for 5–6 h. During this time, the target molecules were
produced and then collected by filtration, washed with n-hexane, and
dried. After isolation of the product, the remaining Et2O in [bmim]Br
was evaporated, and it was used for the next run under identical
reaction conditions.
Some Selected Spectral Data of the Products
(E)-N-Benzylidenebenzenesulfonamide (Table 2, Entry 1)
White solid; 1H NMR (CDCl3): d 7.61 (m, 6H), 8.02 (m, 4H), 9.05 (s, 1H);
13C NMR (CDCl3): d 127.1, 128.3, 129.5, 130.3, 131.7, 132.8, 134.0,
136.1.0, 171.2; MS (m=z): 245 (Mþ). Anal. calcd. for C13H11NO2S: C,
63.65; H, 4.52; N, 5.71. Found: C, 63.47; H, 4.37; N, 5.90.
(E)-N-(2-Oxoindolin-3-ylidene)benzenesulfonamide (Table 2, Entry 9)
1
Orange solid; H NMR (DMSO-d6): d 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): d 112.2, 117.8, 122.7, 124.6, 125.5, 128.8, 131.7,
138.3, 144.1, 150.7, 159.3, 184.3; MS (m=z): 286 (Mþ). Anal. calcd. for
C14H10N2O3S: C, 58.73; H, 3.52; N, 9.78. Found: C, 58.52; H, 3.68; N,
9.61%.
(E)-N-(4-Isoperopyl-benzylidene)-4-methylbenzenesulfonamide
(Table 2, Entry 11)
1
White solid; H NMR (CDCl3): d 1.20 (d, J ¼ 7 Hz, 6H), 2.33 (s, 3H),
2.93 (m, 1H), 7.18–7.80 (m, 8H), 8.91 (s, 1H); 13C NMR (CDCl3): d
22.4, 22.5, 32.9, 126.1, 126.7, 128.6, 129.3, 130.3, 130.9, 132.9, 156.7,
171.4; MS (m=z): 301 (Mþ). Anal. calcd. for C17H19NO2S: C, 67.74; H,
6.35; N, 4.65. Found: C, 67.91; H, 6.57; N, 4.41%.

3162
A. Zare et al.
ACKNOWLEDGMENTS
The authors appreciate Payame Noor University and Persian Gulf
University Research Councils for the financial support of this work.
REFERENCES
1. (a) Li, X.; Eli, W.; Li, G. Solvent-free synthesis of benzoic esters and benzyl
esters in novel Brønsted acidic ionic liquids under microwave irradiation.
Catal. Commun. 2008, 9, 2264–2268; (b) Ranu, B. C.; Banerjee, S. Ionic liquid
as reagent: A green procedure for the regioselective conversion of epoxides to
vicinal-halohydrins using [AcMIm]X under catalyst- and solvent-free condi-
tions. J. Org. Chem. 2005, 70, 4517–4519; (c) Azizi, N.; Aryanasab, F.; Saidi,
M. R. Straightforward and highly efficient catalyst-free one-pot synthesis
of dithiocarbamates under solvent-free conditions. Org. Lett. 2006, 8,
5275–5277; (d) Potewar, T. M.; Ingale, S. A.; Srinivasan, K. V. Catalyst-free
efficient synthesis of 2-aminothiazoles in water at ambient temperature.
Tetrahedron 2008, 64, 5019–5022; (e) Geuens, J.; Kremsner, J. M.; Nebel,
B. A.; Schober, S.; Dommisse, R. A.; Mittelbach, M.; Tavernier, S.; Kappe,
C. O.; Maes, B. U. W. Microwave-assisted catalyst-free transesterification of
triglycerides with 1-butanol under supercritical conditions geuens. Energy
Fuels 2008, 22, 643–645; (f) Shrikhande, J. J.; Gawande, M. B.; Jayaram,
R. V. A. Catalyst-free N-benzyloxycarbonylation of amines in aqueous
micellar media at room temperature. Tetrahedron Lett. 2008, 49, 4799–
4803; (g) Ogawa, T.; Watanabe, J.; Oshima, Y. Catalyst-free synthesis of
polyorganosiloxanes by high temperature and pressure water. J. Supercrit.
Fluid 2008, 45, 80–87; (h) Wei, Y.; Ren, H.; Wang, J. Solvent- and
catalyst-free gem-bisallylation of carboxylic acid derivatives with allylzinc
bromide. Tetrahedron Lett. 2008, 49, 5697–5699; (i) Ranu, B. C.; Dey, S.
S.; Hajra, A. Solvent-free, catalyst-free Michael-type addition of amines to
electron-deficient alkenes. Arkivoc 2002, 7, 76–81.
2. (a) Zare, A.; Hasaninejad, A.; Beyzavi, M. H.; Moosavi Zare, A. R.;
Khalafi-Nezhad, A.; Asadi, F.; Baramaki, L.; Jomhori-Angali, S.; Ghaleh-
Golabi, R. KF=Al2O3 as a highly efficient, green, heterogeneous, and reusa-
ble catalytic system for the solvent-free synthesis of carboacyclic nucleosides
via Michael addition reaction. Synth. Commun. 2009, 39, 139–157; (b)
Hasaninejad, A.; Zare, A.; Zolfigol, M. A.; Shekouhy, M. Zirconium tetra-
kis(dodecyl sulfate) [Zr(DS)4] as an efficient Lewis acid–surfactant combined
catalyst for the synthesis of quinoxaline derivatives in aqueous media. Synth.
Commun. 2009, 39, 569–579; (c) Soltani Rad, M. N.; Khalafi-Nezhad, A.;
Behrouz, S.; Faghihi, M. A.; Zare, A.; Parhami, A. One-pot synthesis of
N-alkyl purine and pyrimidine derivatives from alcohols using TsIm: A
rapid entry into carboacyclic nucleoside synthesis. Tetrahedron 2008, 64,
1778–1785; (d) Khalafi-Nezhad, A.; Parhami, A.; Zare, A.; Moosavi Zare,
A. R.; Hasaninejad, A.; Panahi, F. Trityl chloride as a novel and efficient

Synthesis of N-Sulfonyl Imines
3163
organic catalyst for room temperature preparation of bis(indolyl)methanes
under solvent-free conditions in neutral media. Synthesis 2008, 617–621; (e)
Hasaninejad, A.; Zare, A.; Mohammadizadeh, M. R.; Shekouhy, M. Oxalic
acid as an efficient, cheap, and reusable catalyst for the preparation of
quinoxalines via condensation of 1,2-diamines with a-diketones at room tem-
perature. Arkivoc, 2008, 13, 28–35; (f) Hasaninejad, A.; Parhami, A.; Zare,
A.; Khalafi-Nezhad, A.; Nasrolahi Shirazi, A.; Moosavi Zare, A. R. Magne-
sium sulfate as an efficient and very cheap reagent for the preparation of
bis(indolyl)methanes. Polish J. Chem. 2008, 82, 565–569; (g) Khalafi-Nezhad,
A.; Parhami, A.; Soltani Rad, M. N.; Zolfigol, M. A.; Zare, A. A catalytic
method for chemoselective detritylation of 50-tritylated nucleosides under
mild and heterogeneous conditions using silica sulfuric acid as a recyclable
catalyst. Tetrahedron Lett. 2007, 48, 5219–5222.
3. Wasserscheid, P.; Welton, T. Ionic Liquids in Synthesis; Wiley-VCH:
Weinheim, 2003; (b) Rogers, R. D. Ionic Liquids as Green Solvents: Progress
and Prospects; American Chemical Society, Washington, DC, 2005.
4. Loupy, A. Microwaves in Organic Synthesis; Wiley-VCH: Weinheim, 2006;
(b) Varma, R. S. Advances in Green Chemistry: Chemical Synthesis Using
Microwave Irradiation; Astra Zeneca Research Foundation: Bangalore,
India, 2002.
5. (a) Nakamura, S.; Sano, H.; Nakashima, H.; Kubo, K.; Shibata, N.; Toru, T.
Enantioselective Mannich-type reaction of sulfonylimines having 2-pyridyl-
sulfonyl group as a novel stereocontroller. Tetrahedron Lett. 2007, 48,
5565–5568; (b) Nakamura, S.; Nakashima, H.; Sugimoto, H.; Shibata, N.;
Toru, T. A new stepwise deprotection method using reductive acidolysis
followed by fluoride ion in solid phase peptide synthesis. Tetrahedron Lett.
2006, 47, 7599–7602; (c) Gohain, M. N-Tosyl imines. Synlett 2003, 2097–2098.
6. (a) Sugimoto, H.; Nakamura, S.; Hattori, M.; Ozeki, S.; Shibata, N.; Toru, T.
Enantioselective nucleophilic addition to N-(2-pyridylsulfonyl)imines by use
of dynamically induced chirality. Tetrahedron Lett. 2005, 46, 8941–8944;
(b) Soeta, T.; Nagai, K.; Fujihara, H.; Kuriyama, M.; Tomioka, K. Asym-
metric alkylation of N-toluenesulfonylimines with dialkylzinc reagents
catalyzed by copper-chiral amidophosphine. J. Org. Chem. 2003, 68, 9723–
9727; (c) Yim, H.-K.; Wong, H. N. C. Diastereoselective addition reactions
of furyl sulfonylimine using chiral boronates as auxiliary: application to the
enantioselective synthesis of 2,3-disubstituted furyl sulfonylamides. J. Org.
Chem. 2004, 69, 2892–2895.
7. (a) Chen, Y.-C.; Wu, T.-F.; Deng, J.-G.; Liu, H.; Cui, X.; Zhu, J.; Jiang, Y.-
Z.; Choi, M. C. K.; Chan, A. S. C. Multiple dendritic catalysts for asym-
metric transfer hydrogenation. J. Org. Chem. 2002, 67, 5301–5306; (b) Hojo,
M.; Murakami, C.; Fujii, A.; Hosomi, A. New reactivity of methoxyhydrido-
silane in the catalytic activation system. Tetrahedron Lett. 1999, 40, 911–914.
8. Akiyama, T.; Sugano, M.; Kagoshima, H. Eine variante zur verbesserten
darstellung von hydroperoxydioxolanen. Tetrahedron Lett. 2001, 42, 3889–3892.
ꢀ
ꢀ
9. Ruano, J. L. G.; Lopez-Cantarero, J.; de Haro, T.; Aleman, J.; Cid, M. B.
Preparation of a-amino ketones, b-amino hydroxylamines using asymmetric

3164
A. Zare et al.
aza-Henry reactions of N-p-tolylsulfinylimines with nitroethane. Tetrahedron
2006, 62, 12197–12203.
10. (a) Boger, D. L.; Corbett, W. L.; Curran, T. T.; Kasper, A. M. Inverse
electron-demand Diels–Alder reactions of N-sulfonyl a,b-unsaturated imines:
A general approach to implementation of the 4pi participation of 1-aza-1,3-
butadienes in Diels–Alder reactions. J. Am. Chem. Soc. 1991, 113, 1713–1729;
(b) Boger, D. L.; Weinreb, S. N. Hetero Diels–Alder Methodology in Organic
Synthesis; Academic Press: San Diego, 1987.
11. (a) Arini, L. G.; Sinclair, A.; Szeto, P.; Stockan, R. A. Direct synthesis of ali-
phatic vinyl aziridines. Tetrahedron Lett. 2004, 45, 1589–1591; (b) Hori, R.;
Aoayama, T.; Shoiri, T. A new preparation of cis-N-sulfonylaziridines from
N-sulfonylaldimines using trimethylsilyldiazomethane. Tetrahedron Lett.
2000, 41, 9455–9458.
12. Zhou, X.-T.; Lin, Y.-R.; Dai, L.-X.; Sun, J.; Xia, L.-J.; Tang, M.-H. A
catalytic enantioselective access to optically active 2-imidazoline from
N-sulfonylimines and isocyanoacetates. J. Org. Chem. 1999, 64, 1331–1334.
13. (a) Melnick, M. J.; Weinreb, S. M.; Freyer, A. Generation and intramolecular
cationic cyclizations of N-tosylimines derived from enolizable aldehydes.
Tetrahedron Lett. 1988, 29, 3891–3894; (b) Tschaen, D. M.; Turos, E.;
Weinreb: S. M. Stereochemical studies of thermal intermolecular and intra-
molecular N-sulfonylimine ene reactions. J. Org. Chem. 1984, 49, 5058–5064.
14. (a) Trost, B. M.; Marrs, C. A convenient synthesis of N-tosylimines. J. Org.
Chem. 1991, 56, 6468–6470; (b) Borger, D. L.; Corbett, W. L. A convenient
and general preparation of N-sulfonylimines. J. Org. Chem. 1992, 57, 4777–
ꢀ
4780; (c) Ruano, J. L. G.; Aleman, J.; Cid, M. B.; Parra, A. A general method
for the preparation of N-sulfonyl aldimines and ketimines. Org. Lett. 2005, 7,
179–182; (d) McFarlane, A. K.; Thomas, G.; Whiting, A. Diastereoselectivity
in the aza-Diels–Alder reaction of a sulfonyl imino acetate with Danishefsky’s
diene. Tetrahedron Lett. 1993, 34, 2379–2382; (e) Li, Z.; Ren, X.; Wei, P.;
Wan, H.; Shi, Y.; Ouyang, P. A convenient preparation of aliphatic and
aromatic N-sulfonylimines mediated by sulfamic acid in aqueous media.
Green Chem. 2006, 433–436; (f) Wolfe, J. P.; Ney, J. E. A new, mild synthesis
of N-sulfonyl ketimines via the palladium-catalyzed isomerization of aziri-
dines. Org. Lett. 2003, 4607–4610.
15. (a) Jin, T.; Feng, G.; Yang, M.; Li, T. A solvent-free procedure for synthesis
2ꢂ
of N-sulfonylimines using microwave irradiation catalyzed by ZrO2=S2O8
solid superacid. Synth. Commun. 2004, 34, 1277–1283; (b) Sharghi, H.;
Hosseini-Sarvari, M.; Ebrahimpourmoghaddam, S. A novel method for the
synthesis of N-sulfonyl aldimines using AlCl3 under solvent-free conditions
(SFC). Arkivoc 2007, 15, 255–264; (c) Love, B. E.; Raje, P. S.; Williams, T.
C. Preparation of N-tosylaldimines. Synlett 1994, 493–494; (d) Vass, A.;
Dudas, J.; Varma, R. S. Solvent-free synthesis of N-sulfonylimines using
microwave irradiation. Tetrahedron Lett. 1999, 40, 4951–4954; (e) Jennings,
W. B.; Lovely, C. J. The titanium tetrachloride induced synthesis of
N-phosphinoylimines and N-sulphonylimines directly from aromatic
aldehydes. Tetrahedron 1991, 47, 5561–5568; (f) Davis, F. A.; Kaminski, J. M.;

Synthesis of N-Sulfonyl Imines
3165
Kluger, E. W.; Freilich, H. S. Chemistry of the sulfur–nitrogen bond, IX:
Transmission of electronic effects in N-alkylidenearenesulfenamides, sulfina-
mides, sulfonamides, and arenesulfenanilides. J. Am. Chem. Soc. 1975, 97,
7085–7091; (g) Davis, F. A.; Nadir, U.; Kluger, E. W.; Sedergran, T. C.; Panunto,
T. W.; Billmers, R.; Jenkins, R.; Turchi, I. J.; Watson, W. H.; Chen, J. S.;
Kimura, M. Chemistry of oxaziridines, 1: Synthesis and structure of
2-arenesulfonyl-3-aryloxaziridines: A new class of oxaziridines. J. Am. Chem.
Soc. 1980, 102, 2000–2005.
16. (a) Hasaninejad, A.; Zare, A.; Sharghi, H.; Shekouhy, M. P2O5=SiO2 an effi-
cient, green and heterogeneous catalytic system for the solvent-free synthesis
of N-sulfonyl imines. Arkivoc 2008, 11, 64–74; (b) Hasaninejad, A.; Zare, A.;
Moosavi Zare, A. R.; Parhami, A.; Sharghi, H.; Khalafi-Nezhad, A. Prepara-
tion of N-sulfonyl imines from sulfonamides and aryl aldehydes using
magnesium oxide as a heterogeneous and reusable catalyst under solvent-free
conditions. Phosphorus, Sulfur Silicon Relat. Elem. 2008, 183, 2769–2776;
(c) Khalafi-Nezhad, A.; Parhami, A.; Zare, A.; Nasrolahi Shirazi, A.;
Moosavi Zare, A. R.; Hasaninejad, A. Triarylmethyl chlorides as novel,
efficient, and mild organic catalysts for the synthesis of N-sulfonyl imines
under neutral conditions. Can. J. Chem. 2008, 86, 456–461; (d) Hasaninejad,
A.; Sharghi, H. A convenient and efficient method for the preparation of
N-sulfonyl aldimines from aromatic aldehydes under solvent-free conditions.
Phosphorus, Sulfur, Silicon Relat. Elem. 2007, 182, 873–880; (e) Hasaninejad,
A.; Zare, A. Silphox [POCl3-n (SiO2)n] as a new, efficient, and heterogeneous
reagent for the preparation of N-sulfonyl imines under solvent-free
conditions. J. Sulfur Chem. 2007, 28, 357–364.
17. Chelma, F.; Hebbe, V.; Normant, J.-F. An easy synthesis of aliphatic and
aromatic N-sulfonyl aldimines. Synthesis 2000, 75–77.
18. Dupont, J.; Consorti, C. S.; Suarez, P. A. Z.; de Souza, R. F. Preparation of
1-butyl-3-methyl imidazolium-based room temperatures ionic liquids. Org.
Synth. 2004, 79, 236–243.