Uronium hydrogen sulfate/urea-hydrogen peroxide as a green and metal-free catalytic system for the efficient, chemo-, and homoselective oxidation of sulfides to sulfoxides

Article abstract of DOI:10.1080/10426507.2010.494919

Chemical Equation Presented An efficient, chemoselective, and metal-free oxidation of sulfides is described using urea-hydrogen proxide (UHP) adduct as a stable, inexpensive, and easily handled reagent in the presence of uronium hydrogen sulfate (UHS). Both UHP and UHS release urea as an environmentally benign byproduct. The advantages of the described method are generality, chemoselectivity, short reaction time, low cost, high atom economy, and green chemistry protocols. Copyright Taylor & Francis Group, LLC.

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Phosphorus, Sulfur, and Silicon and the
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Uronium Hydrogen Sulfate/Urea-
Hydrogen Peroxide as a Green and Metal-
Free Catalytic System for the Efficient,
Chemo-, and Homoselective Oxidation of
Sulfides to Sulfoxides
a
b
Alireza Hasaninejad , Gholamabbas Chehardoli , Mohammad Ali
c
c
Zolfigol & Abbas Abdoli
a
Department of Chemistry, Faculty of Sciences , Persian Gulf
University , Bushehr, Iran
b
School of Pharmacy , Hamedan University of Medical Sciences ,
Hamedan, Iran
c
Faculty of Chemistry , Bu-Ali Sina University , Hamedan, Iran
Published online: 19 Feb 2011.
To cite this article: Alireza Hasaninejad , Gholamabbas Chehardoli , Mohammad Ali Zolfigol & Abbas
Abdoli (2011) Uronium Hydrogen Sulfate/Urea-Hydrogen Peroxide as a Green and Metal-Free Catalytic
System for the Efficient, Chemo-, and Homoselective Oxidation of Sulfides to Sulfoxides, Phosphorus,
Sulfur, and Silicon and the Related Elements, 186:2, 271-280, DOI: 10.1080/10426507.2010.494919
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Phosphorus, Sulfur, and Silicon, 186:271–280, 2011
Copyright ꢀ
Taylor & Francis Group, LLC
C
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2010.494919
URONIUM HYDROGEN SULFATE/UREA-HYDROGEN
PEROXIDE AS A GREEN AND METAL-FREE CATALYTIC
SYSTEM FOR THE EFFICIENT, CHEMO-, AND
HOMOSELECTIVE OXIDATION OF SULFIDES
TO SULFOXIDES
1
2
Alireza Hasaninejad, Gholamabbas Chehardoli,
3
3
Mohammad Ali Zolfigol, and Abbas Abdoli
Department of Chemistry, Faculty of Sciences, Persian Gulf University,
Bushehr, Iran
1
2
School of Pharmacy, Hamedan University of Medical Sciences,
Hamedan, Iran
3
Faculty of Chemistry, Bu-Ali Sina University, Hamedan, Iran
GRAPHICAL ABSTRACT
.
.
S
O
R
R'
H O .... H N
H SO
2
2
2
NH2
2
4
UHP
H O
2
O
H N
2
NH2
O
O
S
OH
O
S
O
R
R'
O
H
H
:
O
O
HSO4 H N
NH2
3
R
H
S:
R'
UHS
Abstract An efficient, chemoselective, and metal-free oxidation of sulfides is described using
urea-hydrogen proxide (UHP) adduct as a stable, inexpensive, and easily handled reagent
in the presence of uronium hydrogen sulfate (UHS). Both UHP and UHS release urea as an
environmentally benign byproduct. The advantages of the described method are generality,
chemoselectivity, short reaction time, low cost, high atom economy, and green chemistry
protocols.
Keywords Chemoselective; oxidation; sulfides; sulfoxides; urea hydrogen peroxide (UHP);
uronium hydrogen sulfate (UHS)
Received 13 April 2010; accepted 16 May 2010.
Financial support for this work by Persian Gulf University, Bushehr, Iran, and Hamedan University of
Medical Sciences, and also the Center of Excellence of Development of Chemical Methods, (CEDCM), Bu-Ali
Sina University, Hamedan, Iran, is gratefully acknowledged.
Address correspondence to Gholamabbas Chehardoli, School of Pharmacy, Hamedan University of Medical
Sciences, 65178 Hamedan, Iran. E-mail: chehardoli@umsha.ac.ir, cheh1002@gmail.com
2
71

272
A. HASANINEJAD ET AL.
INTRODUCTION
The art of performing efficient chemical transformations by catalytic processes avoid-
ing toxic byproducts, expensive catalysts, and difficult–to-handle reagents represents a
1
fundamental target of modern organic synthesis. Also, the search for safe and easily acces-
sible sources of primary oxidants is of great interest in chemistry. In particular, reduction
in the amount of hazardous wastes in the reactions would be welcome in term of green
2
chemistry.
Sulfoxides are fascinating organic molecules. These compounds have immense ap-
3
plications in the field of sulfur-substituted natural products and also in pharmaceuticals.
Because of the multifarious conversions of sulfoxides into a myriad of organosulfur com-
pounds, they are extremely important to organic chemists. Much exploration has been
4
carried out to understand their importance as chiral auxiliary in asymmetric synthesis and
5
particularly in carbon–carbon bond forming reactions. Oxidation of sulfides is a general
6
method for synthesis of sulfoxides. Several methods have been introduced for this pur-
7
pose. However, most of the existing methods use sophisticated reagents, complex catalysts,
toxic metallic compounds, or rare oxidizing agents that are difficult to prepare. Also, many
7
of these procedures also suffer from poor selectivity.
Urea hydrogen peroxide (UHP) is a white crystalline solid, formed by strong hydrogen
8
bonding between urea and hydrogen peroxide in a 1:1 proportion ; it is easily handled,
without the need for special precautions. It is commercially available, cheap, and can be
◦
stored for months at +4 C without any change in the oxygen content, and, in contrast to
other oxidizing agents, UHP is the most attractive oxidant from an environmental viewpoint
9
and shows safety in operation. However, UHP alone cannot oxidize sulfides to sulfoxides
at room temperature.10 Therefore, there is a need to improve the ability of UHP for the
selective conversion of sulfides to sulfoxides. Uronium hydrogen sulfate (UHS) is a very
cheap and stable solid acid whose application in synthetic methodology has already been
reported. Another advantage of the using of UHS is reduction of toxic byproducts, because
11
the uranium cation is a green and safe waste.
RESULTS AND DISCUSSION
In continuation of our interest in the development of synthetic methodologies for
1
2
13,14
organic functional grouptransformations, H2O2 adducts, catalyticoxidationreactions,
11
and the application of UHS in organic synthesis, in the present work we have used
a stable solid urea/hydrogen peroxide addition compound (UHP) as the safe and eco-
friendly oxidant for selective oxidation of thioethers into the corresponding sulfoxides in
the presence of a catalytic amount of UHS as a very cheap, stable, and recyclable solid acid
catalyst (Scheme 1).
Initially, in order to optimize reaction conditions, the oxidation of methyl phenyl
sulfide into methyl phenyl sulfoxide using UHP in methanol was selected as a model
reaction (Scheme 2). The results are summarized in Table 1. At first, a model run was
carried out with methyl phenyl sulfide in the absence of catalyst. It was found that even
using a 10-fold excess of H2O2, the reaction was not completed after a long reaction time
(4 h) (Table 1, entries 1 and 2). Then, the effects of various amounts of UHS as a catalyst
on the reactivity of UHP for the oxidation of methyl phenyl sulfide in methanol at room
temperature have been studied. The results show that UHSis an effective catalyst for the
sulfoxidation reaction with high yield and short reaction time. Also in this study, the effects

URONIUM HYDROGEN SULFATE/UREA-HYDROGEN PEROXIDE
273
O
S
O
S
UHP (2 mmol)
S
R
R'
R
R'
R
R' +
UHS (0.1 mmol),
O
CH
3
OH, r.t.
1
00%
0%
R, R': Alkyl, Aryl
O
UHP: H N
NH ...H-O-O-H
2.
2
O
UHS: H N
NH HSO
4
2
3
Scheme 1
O
S
S
UHP(2 mmol)
Cat. CH OH, r.t.
3
Scheme 2
of various amounts of UHP were checked (Table 1, entries 3–7). As is shown in Table 1,
higher yield and acceptable reaction time for sulfoxidation reactions were obtained when
0.1 mmol UHS was used for the reaction of 1 mmol methyl phenyl sulfide and 2 mmol
UHP in 5 mL CH3OH at room temperature (Table 1, entry 4).
Table 1 Oxidation of benzyl phenyl sulfide (1 mmol) to the corresponding sulfoxide using UHP in the presence
of representative catalyst in CH3OH (5 mL) at room temperature
Entry
Catalyst (mmol)
UHP (mmol)
Time (h)
Yield of sulfoxide (%)a
b
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
—
2
10
1
2
2
4
4
2
2
2
2
2
2
2
2
2
2
4
4
Trace
30
97
95
97
b
—
UHS (0.1)
UHS (0.1)
UHS (0.2)
UHS (0.4)
50 (min)
30 (min)
25 (min)
20 (min)
95
UHS (0.1)
25 (min)
86
c
AlCl3 (0.5)
Al(HSO4)3 (0.5)
Na2HPO4 (0.5)
ZnCl2 (0.3)
CaCl2.2H2O (0.5)
Al2O3 (0.5 g)
SiO2 (0.5 g)
ZrCl4 (0.2)
NaHSO4
3
3
3
3
3
3
3
3
3
3
3
3
—
—
c
1
1
1
1
1
1
1
1
1
1
Trace
35
20
Trace
20
Trace
Trace
Trace
Trace
ZnO (0.5)
MgO (0.5)
NH2SO3H
2
2
c
–
a
Isolated yield.
In the absence of catalyst.
Reaction did not complete.
b
c

274
A. HASANINEJAD ET AL.
Table 2 Solvent effect in the oxidation of benzyl phenyl sulfide using UHP in the presence of UHS as catalyst
Entry
Solvent
Time (h)
Yield (%)a
1
2
3
4
5
6
7
8
9
CH2Cl2
CHCl3
EtOAc
Acetone
n-Hexane
THF
CH3CN
DMF
CH3OH
C2H5OH
H2O
5
5
5
24
5
5
24
5
30 (min)
24
0
0
Trace
35
0
0
40
0
100
50
1
1
0
1
24
Trace
aConversion.
In the next step, we investigated the effect of various solvents on the progress of
reactions. As is evident from Table 2, the best choice for the selective sulfoxidation by the
described procedure is methanol.
In order to investigate the scope and limitations of this procedure, the oxidation of
other sulfides was also studied. A good range of substrates such as aryl alkyl, diaryl, and
dialkyl sulfides have been selectively oxidized to their corresponding sulfoxides (Table 3).
CHEMO- AND HOMOSELECTIVITY14g
It is noteworthy that sulfides containing functional groups such as alcohol, acid, and
ester are oxidized selectively without any interference from these groups (Table 3, entries
7, 9, and 10). For example, two sulfides containing a hydroxyl group were subjected to
the sulfoxidation reaction, but alcohol oxidation did not occur under mentioned conditions,
and the primary hydroxyl group remained intact in the course of the reaction (Scheme 3).
Also, it is noteworthy that the mentioned oxidizing system allowed the homose-
lective14g oxidation of bis-(methyl thio)-methane to its monosulfoxide derivative without
further oxidation to di-sulfoxide or sulfone (Scheme 4, entry 12).
O
S
UHP(2 mmol)
S
S
OH
OH
+
O
UHS (0.1mmol),
CH OH, 30 min
3
100%
0%
O
S
UHP(2 mmol)
S
O
S
OH
OH
+
UHS (0.1mmol),
CH OH, 30 min
3
100%
0%
Scheme 3

URONIUM HYDROGEN SULFATE/UREA-HYDROGEN PEROXIDE
275
Table 3 Chemoselective oxidation of sulfides (1 mmol) to their corresponding sulfoxide using UHP (2 mmol)
in the presence of UHS (0.1 mmol) as catalyst in CH3OH (5 mL) at room temperature
Entry
1
Substrate
Product
Time (min)
50
Yield (%)a
92
Ref.b
14d
O
S
S
2
3
30
6h
95
85
7j
O
S
S
S
14e
O
S
4
3h
—c
—
S
O
S
N
H
N
H
5
6
120
30
95
95
7k
S
O
S
14e
S
O
S
CH3
CH3
7
50
88
14e
S
O
S
OH
OH
8
9
40
20
80
82
7m
7j
S
O
S
S
S
O
S
OCH3
O
OCH3
O
1
1
0
1
45
50
91
90
14f
OH
O
S
OH
14d
CO H
O
S
2
CO H
S
2
(
Continued on next page)

276
A. HASANINEJAD ET AL.
Table 3 Chemoselective oxidation of sulfides (1 mmol) to their corresponding sulfoxide using UHP (2 mmol)
in the presence of UHS (0.1 mmol) as catalyst in CH3OH (5 mL) at room temperature (Continued)
Entry
Substrate
Product
Time (min)
20
Yield (%)a
87
Ref.b
14f
1
1
2
3
S
S
O
S
S
25
97
14e
S
O
S
Me
Me
Me
Me
a
Isolated yields.
b
All products are known and were identified using comparison of their physical and spectral data (IR, NMR,
or MS) with those reported in the literature.
c
Undesired products.
O
S
O
S
O
S
S
S
UHP(2 mmol)
S
+
UHS (0.1mmol),
CH OH, 30 min
0%
3
100%
Scheme 4
To further determine the chemoselectivity of the described system, some competitive
reactions were designed. We have monitored competitive oxidation of sulfides in the pres-
ence of sulfoxide, aldehyde, oxime, nitrile, benzylic alcohol, and alkene. The results show
that this method is applicable for the chemoselective oxidation of sulfides to sulfoxides
in the presence of the previously mentioned functional groups and can be considered as
a useful practical achievement in oxidation of sulfides to sulfoxides without the overall
oxidation (Scheme 5).
In Table 4, the results of the oxidation of benzyl phenyl sulfide by our method are
compared with those reported by other methods. As can be seen, this method is superior
to some previously reported methods in terms of chemoselectivity, yields, reaction times,
and amount of the catalyst/reagent for successful oxidation without the need of complex
catalysts, hazardous and unstable oxidants, microwave, or toxic metallic compounds.
The observation of oxidation of benzyl phenyl sulfide and dibenzyl sulfide to the
corresponding sulfoxide (Table 3, entries 1 and 2) indicates that the reaction proceeds
via an oxygen transfer mechanism. If the reaction involved electron transfer instead of
15
oxygen transfer, substantial amounts of benzaldehyde would have been formed. Ac-
cording to a literature survey,7
k,16
the proposed mechanism for the oxidation of sulfide to
the corresponding sulfoxide using UHP in the presence of UHS is outlined as shown in
Scheme 6.
In summary, we found that UHS efficiently catalyzed chemo- and homoselective
oxidation of sulfides to sulfoxides by the UHP adduct at room temperature without overox-
idation to sulfone. Moreover, the simplicity of the operation, low cost of the reagents, and
high yields of sulfoxides are the advantages of this method. Also, its compatibility with sen-
sitive functionalities such as ester, aldehyde, oxime, nitrile, and double bonds with regard
to economic and ecological consideration allows us to believe that this method represents
a valuable alternative to the existing reagents reported in the literature.

URONIUM HYDROGEN SULFATE/UREA-HYDROGEN PEROXIDE
277
O
O
O
O
S
S
S
S
S
UHP(2 mmol)
Me
Me
Me
Me
a:
b:
+
+
+
+
UHS (0.1mmol),
CH OH, 30 min
3
1
00%
00%
0
%
O
S
Me
CHO
Me
COOH
CHO
UHP(2 mmol)
UHS (0.1mmol),
CH OH, 30 min
3
1
0
%
O
S
S
S
H
Me
Me
C NOH UHP(2 mmol)
Me
c:
d:
+
+
+
UHS (0.1mmol),
CH OH, 30 min
3
1
00%
0
%
O
S
O
C N
UHP(2 mmol)
Me
C NH2
UHS (0.1mmol),
+
CH OH, 30 min
3
1
00%
0
%
O
S
S
S
Me
Me
OH
Me
CHO
e:
UHP(2 mmol)
+
+
UHS (0.1mmol),
CH OH, 30 min
100%
3
0
%
O
S
f:
UHP(2 mmol)
Me
O
+
+
UHS (0.1mmol),
CH OH, 30 min
3
1
00%
0
%
Scheme 5
EXPERIMENTAL
Chemicals were purchased from Fluka, Merck, and Aldrich chemical companies.
Yields refer to isolated pure products. The oxidation products were characterized by com-
1
13
parison of their spectral (IR, H NMR, and C NMR) and physical data with those authentic
7
,14
samples, which were produced by other reported procedures.
General Procedure for the Oxidation of Sulfides
A mixture of sulfides (1 mmol), UHP (2 mmol), and UHS (0.1 mmol) in methanol
5 mL) was vigorously stirred for the appropriate time (see Table 3). The progress of the
(
reaction was monitored by TLC. When the reaction was completed, the reaction mixture

278
A. HASANINEJAD ET AL.
.
.
S
O
R
R'
H O .... H N
H SO
2
2
2
NH2
2
4
UHP
H O
2
O
H N
NH2
2
O
S
OH
O S O
R
R'
O
H
O
H
:
O
O
H
HSO4 H N
NH2
3
R
S:
R'
UHS
Scheme 6 Proposed mechanism for the oxidation of sulfide to the corresponding sulfoxide with urea hydrogen
peroxide (UHP) in the presence of uronium hydrogen sulfate (UHS) as catalyst.
was filtered and the residue was washed with CH3OH (2 × 5 mL). Then anhydrous Na2SO4
(4 g) was added to the filtrate and filtered off after 15 min. The solvent was evaporated,
and the crude product was purified by a short column chromatography on silica gel with
EtOAc/n-hexane (1:5 to 1:2).
Table 4 Comparison of oxidation of benzyl phenyl sulfide (1 mmol) by the UHP/UHS system with some of
those reported methods in the literature
Yield (%)
Entry
Reagent (oxidant/substrate)
UHP/UHS/CH3OH/rt (2:0.1)
BTPPDC/AlCl3/CH3CN/reflux (1.5:1)
BTPPDC/AlCl3/MW (1.2:1)
Time (min) Sulfoxide Sulfone
Ref.
a
1
2
3
4
5
6
7
8
9
50
90
2
92
93
94
83
88
88
96
—
93
92
96
96
95
92
93
83
—
—
—
—
—
—
—
This work
a
a
a
a
a
a
7i
7i
NaIO4/wet SiO2/MW (1.7:1)
2.5
7o
7p
7q
7r
7i
7j
7j
7n
7k
7l
PhCH2PPh3HSO5/CH3CN/reflux (1.5:1)
Ba(MnO4)2/CH3CN/reflux (6:1)
CAN/wet SiO2/CH2Cl2/rt (2:1)
BTPPDC/AlCl3/MW (2.5:1)
CPCC/AlCl3/CH3CN/reflux (1:1)
CPCC/AlCl3/MW (0.8:1)
12 (h)
4 (h)
45
a
2.5
97
a
75
1.5
2
40
6.5 (h)
7.5 (h)
170
4 (h)
—
—
—
—
—
—
—
—
a
a
a
a
a
a
a
1
1
1
1
1
1
1
0
1
2
3
4
5
6
H2O2/ZrCl4/CH3OH (7:2)
H2O2/Silica sulfuric acid/CH3CN/rt (1:0.1 g)
H2O2/Amberlyst 15/CH3OH/rt (2:0.5)
H2O2/Amberlyst IR-400/CH3OH/rt (3:0.5)
7l
7m
7s
◦
HIO3/wet SiO2/solvent-free 50 C (1:3)
H2O2/Silica-based tungstate/CH2Cl2, CH3OH (4:0.1)
aNone reported.

URONIUM HYDROGEN SULFATE/UREA-HYDROGEN PEROXIDE
279
REFERENCES
1
2
. Mizzuno, N.; Misono, M. Chem. Rev. 1998, 98, 199.
. (a) Cooper, M. S.; Heaney, H.; Newbold, A. J.; Sanderson, W. R. Synlett 1990, 533; (b) Heany,
H. Aldrichimica Acta 1993, 26, 35.
3. (a) Holland, H. L. Chem. Rev. 1988, 88, 473; (b) Block, E. Angew. Chem. Int. Ed. Engl. 1992,
31, 1135; (c) Fernandez, I.; Khiar, N. Chem. Rev. 2003, 103, 3651.
4. (a) Solladie, G. Synthesis 1981, 185; (b) Arreno, M. C. Chem. Rev. 1995, 95, 1717; (c) Davis,
S. G.; Loveridge, T.; Clough, J. M. Synlett 1997, 66.
5
6
. (a) Magnus, P. D. Tetrahedron 1977, 33, 2019; (b) Madesclaire, M. Tetrahedron 1988, 44, 6537.
. Patai, S.; Rappoport, Z. The Synthesis of Sulfones, Sulfoxides, and Cyclic Sulfides; Wiley; New
York, 1994.
7. (a) Kaczorowska, K.; Kolarska, Z.; Mitka, K.; Kowalski, P. Tetrahedron 2005, 61, 8315, and
references cited therein; (b) Kinen, C. O.; Rossi, L. I.; Rossi, R. H. Appl. Catal. A: General 2006,
312, 120; (c) Hosseinpoor, F.; Golchoubian, H. Tetrahedron Lett. 2006, 47, 5195; (d) Nenajdenko,
V. G.; Gavryushin, A. E.; Balenkova, E. S. Tetrahedron Lett. 2001, 42, 4397; (e) Tajbakhsh, M.;
Hosseinzadeh, R.; Shakoori, A. Tetrahedron Lett. 2004, 45, 1889; (f) Ozanne-Beaudenon, A.;
Quideau, S. Tetrahedron Lett. 2006, 47, 5869; (g) Al-Hashimi, M.; Fisset, E.; Sullivan, A. C.;
Wilson, J. R. H. Tetrahedron Lett. 2006, 47, 8017; (h) Surendra, K.; Krishnaveni, N. S.; Kumar,
V. P.; Sridhar, R.; Rao, K. R. Tetrahedron Lett. 2005, 46, 4581; (i) Ali, M. H.; Stricklin, S. Synth.
Commun. 2006, 36, 1779; (j) Iranpoor, N.; Firouzabadi, H.; Pourali, A. R. Synlett 2004, 347;
(k) Mohammadpoor-Baltork, I.; Memarian, H. R.; Bahrami, K.; Esmyilpour, K. Phosphorus,
Sulfur Silicon Relat. Elem. 2005, 180, 2751; (l) Mohammadpoor-Baltork, I.; Memarian, H. R.;
Bahrami, K. Can. J. Chem. 2005, 83, 115; (m) Shaabani, A.; Rezayan, A. H. Catal. Commun.
2007, 8, 1112; (n) Lakouraj, M. M.; Tajbakhsh, M.; Tashakkorian, H. Monatsh. Chem. 2007,
138, 83; (o) Lakouraj, M. M.; Tajbakhsh, M.; Shirini, F.; Tamami, M. V. A. Synth. Commun.
2005, 35, 775; (p) Bahrami, K. Tetrahedron Lett. 2006, 47, 2009; (q) Varma, R. S.; Saini, R. K.;
Meshram, H. M. Tetrahedron Lett. 1997, 38, 6525; (r) Hajipour, A. R.; Mallakpour, S. E.; Adibi,
H. J. Org. Chem. 2002, 67, 8666; (s) Firouzabadi, H.; Seddighi, M. Synth. Commun. 1991, 21,
211; (t) Ali, M. H.; Leach, D. R.; Schmitz, C. E. Synth. Commun. 1998, 28, 2969; (u) Karimi,
B.; Ghoreishi-Nezhad, M.; Clark, J. H. Org. Lett. 2005, 7, 625;
8
9
. (a) Lu, C. S.; Hughes, E. W.; Giguere, P. A. J. Am. Chem. Soc. 1941, 63, 1507 (b) Adia, K. J.
Inorg. Nucl. Chem. 1963, 25, 165.
. Deligeorgiev, T.; Vasilev, A.; Vaquero, J. J.; Alvarez-Builla, J. Ultrason. Sonochem. 2007, 14,
497.
10. Varma, R. S.; Naicker, K. P. Org. Lett. 1999, 1, 189.
1
1. (a) Zolfigol, M. A.; Choghamarani, A. G.; Taqian-Nasab, A.; Keypour, H.; Salehzadeh, S. Bull.
Kor. Chem. Soc. 2003, 24, 638; (b) Salehi, P.; Dabiri, M.; Zolfigol, M. A.; Baghbanzadeh, M.
Heterocycles 2005, 5, 1177.
1
2. (a) Chehardoli, G.; Zolfigol, M. A.; Faal-Rastegar, T.; Ghorbani-Choghamarani, S. A. J. Chem.
Sci. 2009, 121, 441; (b) Niknam, K.; Zolfigol, M. A.; Chehardoli, G.; Dehghanian, M. Chin. J.
Catal. 2008, 29, 901; (c) Zolfigol, M. A.; Chehardoli, G.; Ghaemi, E.; Madrakian, E.; Zare, R.;
Azadbakht, T.; Niknam, K.; Mallakpour, S. Monatsh. Chem. 2008, 139, 261; (d) Zolfigol, M. A.;
Ghorbani-Vaghei, R.; Mallakpour, S.; Chehardoli, G.; Choghamarani, A. G.; Hosein-Yazdi, A.
Synthesis 2006, 1631; (e) Bamoniri, A.; Mirjalili, B. F.; Zolfigol, M. A.; Mohammadpoor-Baltork,
I. J. Iran. Chem. Soc. 2007, 4, 332; (f) Shirini, F.; Zolfigol, M. A.; Abri, A. R. J. Iran. Chem. Soc.
2008, 5, 96; (g) Mirjalili, B. F.; Zolfigol, M. A.; Bamoniri, A.; Karimi-Zarchi, M. A.; Zaghaghi,
Z.; Parvaideh, M. J. Iran. Chem. Soc. 2007, 4, 340; (h) Bamoniri, A.; Mirjalili, B. F.; Zolfigol, M.
A.; Mohammadpoor-Baltork, I. J. Iran. Chem. Soc. 2007, 4, 332; (i) Mohammadpoor-Baltork, I.;
Moghadam, M.; Tangestaninejad, S.; Mirkhani, V.; Zolfigol, M. A.; Hojati, S. F. J. Iran. Chem.
Soc. 2008, 5, S65; (j) Zolfigol, M. A.; Mokhlesi, M. J. Iran. Chem. Soc. 2008, 5, S91; (k) Shirini,
F.; Zolfigol, M. A.; Shahriari, A. J. Iran. Chem. Soc. 2008, 5, 3; (l) Zolfigol, M. A.; Salehi, P.;

280
A. HASANINEJAD ET AL.
Shiri, M.; Rastegar, T. F.; Ghaderi, A. J. Iran. Chem. Soc. 2008, 5, 490; (m) Zolfigol, M. A.;
Mohammadpoor-Baltork, I.; Shiri, M. J. Iran. Chem. Soc. 2008, 5, 90.
1
3. (a) Chehardoli, G.; Zolfigol, M. A. Phosphorus, Sulfur Silicon Relat. Elem. 2010, 185, 193;
b) Zolfigol, M. A.; Salehi, P.; Shiri, M. Phosphorus, Sulfur Silicon Relat. Elem. 2004, 179,
273; (c) Zolfigol, M. A.; Mohammadpoor-Baltork, I.; Shiri, M. J. Chin. Chem. Soc. 2006, 53,
45; (d) Niknam, K.; Zolfigol, M. A.; Razavian, S. M.; Mohammadpoor-Baltork, I. Heterocycles
005, 65, 657; (e) Damavandi, J. A.; Karami, B.; Zolfigol, M. A. Synlett 2002, 933; (f) Zolfigol,
(
2
5
2
M. A.; Chehardoli, G.; Shiri, M. React. Funct. Polym. 2007, 67, 723; (g) Zolfigol, M. A.;
Bagherzadeh, M.; Chehardoli, G.; Mallakpour, S. E.; Mamaghani, M. J. Chem. Res. (S) 2001,
390; (h) Zolfigol, M. A.; Salehi, P.; Mallakpour, S. E.; Torabi, M. Bull. Chem. Soc. Jpn. 2003,
76, 1673.
1
4. (a) Zolfigol, M. A.; Shirini, F.; Chehardoli, G.; Kolvari, E. J. Mol. Catal. A: Chem. 2006,
65, 271; (b) Zolfigol, M. A.; Bagherzadeh, M.; Mallakpour, S.; Chehardoli, G.; Ghorbani-
Choghamarani, A.; Koukabi, N.; Dehghanian, M.; Doroudgar, M. J. Mol. Catal. A: Chem. 2007,
70, 219; (c) Zolfigol, M. A.; Bagherzadeh, M.; Mallakpour, S.; Chehardoli, G.; Koukabi, N.
2
2
Catal. Commun. 2007, 8, 256; (d) Habibi, D.; Zolfigol, M. A.; Safaiee, M.; Shamsian, A.;
Ghorbani-Choghamarani, A. Catal. Commun. 2010, 10, 1257; (e) Zolfigol, M. A.; Amani, K.;
Ghorbani-Choghamarani, A.; Hajjami, M.; Ayazi-Nasrabadi, R.; Jafari, S. Catal. Commun. 2008,
9, 1739; (f) Ghorbani-Choghamarani, A.; Zolfigol, M. A.; Ayazi-Nasrabadi, R. J. Braz. Chem.
Soc. 2010, 21, 33.
1
1
5. Baciocchi, E.; Lanzalunga, O.; Malandrucco, S. J. Am. Chem. Soc. 1996, 118, 8973.
6. Firouzabadi, H.; Iranpoor, N.; Jafari, A. A.; Riazymontazer, E. Adv. Synthetic Catal. 2006, 348,
434.