Polyvinylpolypyrrolidone-supported hydrogen peroxide (PVP-H 2O2), silica sulfuric acid and catalytic amounts of ammonium bromide as green, mild and metal-free oxidizing media for the efficient oxidation of alcohols and sulfides

Article abstract of DOI:10.1007/BF03246566

Polyvinylpolypyrrolidone-supported hydrogen peroxide (PVP-H ₂O₂), silica sulfuric acid (SiO₂OSO ₃H) and catalytic amounts of ammonium bromide (NH₄Br) are introduced as green media for the in situ generation of bromoniume ion (Br ⁺), which was applied for the selective oxidation of sulfides and alcohols into sulfoxides and carbonyl compounds, respectively. The oxidation reactions were carried out heterogeneously in acetonitrile, as solvent, at room temperature (oxidation of sulfides) and/or 60 °C (oxidation of alcohols).

Full text of DOI:10.1007/BF03246566

J. Iran. Chem. Soc., Vol. 8, No. 4, December 2011, pp. 1082-1090.
JOURNAL OF THE
Iranian
Chemical Society
Polyvinylpolypyrrolidone-Supported Hydrogen Peroxide (PVP-H O ), Silica Sulfuric
2
2
Acid and Catalytic Amounts of Ammonium Bromide as Green, Mild and Metal-Free
Oxidizing Media for the Efficient Oxidation of Alcohols and Sulfides
A. Ghorbani-Choghamarani* and G. Azadi
Department of Chemistry, Faculty of Science, Ilam University, P.O. Box 69315516, Ilam, Iran
(
Received 8 January 2011, Accepted 26 May 2011)
Polyvinylpolypyrrolidone-supported hydrogen peroxide (PVP-H
of ammonium bromide (NH
2
O
2
), silica sulfuric acid (SiO
2
OSO
3
H) and catalytic amounts
+
4
Br) are introduced as green media for the in situ generation of bromoniume ion (Br ), which was
applied for the selective oxidation of sulfides and alcohols into sulfoxides and carbonyl compounds, respectively. The oxidation
reactions were carried out heterogeneously in acetonitrile, as solvent, at room temperature (oxidation of sulfides) and/or 60 ºC
(
oxidation of alcohols).
Keywords: Polyvinylpolypyrrolidone-H O , Ammonium bromide, Silica sulfuric acid, Sulfide, Alcohol, Oxidation
2
2
INTRODUCTION
is via oxidation of the corresponding sulfides. There are
several procedures available for this key transformation, which
is typically achieved using stoichiometric or catalytic amounts
of both organic and inorganic reagents [10-18].
Moreover, the chemoselective oxidation of alcohols to the
corresponding carbonyl compounds is an important
transformation in synthetic organic chemistry, as aldehydes
and ketones are essential for the preparation of many key
synthetic intermediates [19-21]. Traditional methods involve
the use of toxic and expensive metal oxidants [22-24], or
require harsh reaction conditions [25-29].
In the last few years, supported reagents on the organic
polymers have been increasingly used in organic functional
group transformations [1-4], mainly because the reactions are
carried out under mild conditions and the organic products are
easily isolated from the reaction media.
The controlled oxidizing of sulfides into sulfoxides is of
great interest in organic chemistry. Oxidation of organo-sulfur
compounds finds application in the removal of sulfur-
containing pollutants during air and wastewater treatment [5].
The long-standing interest in the sulfoxidation of organic
sulfides is due to their utility in diverse areas of chemistry
originating from the constant use of sulfoxides as chiral
auxiliaries in total synthesis, as well as useful important
synthetic intermediates for the construction of various
chemically and biologically active molecules [6-9]. The
common synthetic procedure for the preparation of sulfoxides
Hydrogen peroxide (H O ) is a powerful oxidizing agent. It
2
2
has been used as an efficient oxidant for the oxidation of
different organic functional groups [30-33]. In order to avoid
the hazards connected with the use of concentrated solution of
H O , this compound has been adducted with some carriers
2
2
such as urea [34], DABCO-di-N-oxide [35], melamine [36]
and polyvinylpolypyrrolidone [37]. From among these,
polyvinylpolypyrrolidone-supported hydrogen peroxide (PVP-
H O ) has many advantages such as insolubility in organic
*Corresponding author. E-mail: arashghch58@yahoo.com
2
2

Ghorbani-Choghamarani & Azadi
solvents, easy work up of products, non-toxic content and mild
mmol) in acetonitrile (10 ml). The resulting mixture was
stirred at 60 ºC for 90 min (the reaction progress was
monitored by TLC). Then the crude product was purified by
short column chromatography using dichloromethane as the
oxidizing properties. Therefore, we decided to investigate the
scope and limitations of this polymeric agent for the oxidation
of sulfides and alcohols.
eluent. Finally, CH Cl2 was evaporated and 4-
2
1
EXPERIMENTAL
bromobenzaldehyde was obtained in 88% yield (0.163 g). H
NMR (400 MHz, CDCl ): δ = 9.98 (s, 1H), 7.76-7.74 (d, J =
8.4 Hz, 2H), 7.70-7.68 (d, J = 8.4 Hz, 2H) ppm; C NMR
3
1
3
Chemicals and Apparatus
Chemicals were purchased from Fluka, Merck and Aldrich
chemical companies. Polyvinylpolypyrrolidone-supported
(100 MHz, CDCl ): δ = 191.0, 135.1, 132.4, 130.9, 129.7
3
ppm.
hydrogen peroxide (PVP-H
2
2
O ) was prepared via the reported
procedure by Pourali and Ghanei [38]. All of the products
RESULTS AND DISCUSSION
1
were characterized by comparison of their spectral (IR, H
1
3
NMR and C NMR) and physical data with authentic
samples.
In order to complete our studies on the application of
polymeric-supported reagents [39-42] in organic functional
group transformations, we attempted to investigate the
chemoselective oxidation of sulfides and alcohols into
sulfoxides and carbonyl compounds by polyvinylpoly-
pyrrolidone-supported hydrogen peroxide (PVP-H O ). PVP-
Oxidation
of
Didodecylsulfane
to
2
1-
(
Dodecylsulfinyl)dodecane Using PVP-H O , Silica
2
Sulfuric Acid and Ammonium Bromide
2
2
PVP-H
2
O
2
(0.290 g), silica sulfuric acid (0.100 g),
H
2
O
2
was prepared via the reported procedure by Pourali and
ammonium bromide (0.050 g, 0.05 mmol) and water (2 drops)
were added to a solution of didodecylsulfane (0.371 g, 1
mmol) in acetonitrile (10 ml). The resulting mixture was
stirred at room temperature for 90 min (the reaction progress
was monitored by TLC) and then filtered. The residue was
washed with CH Cl (20 ml). The reaction mixture was dried,
Ghanei [38].
Our recent studies are aimed at in situ generation of
bromoniume ion (Br ) and its applications in different organic
reactions [43-47]. To this end, we decided to design a new
metal-free catalytic system including polyvinylpoly-
pyrrolidone-supported hydrogen peroxide (PVP-H O ), silica
+
2
2
2
2
washed with water (5
dichloromethane. Anhydrous Na SO (3 g) was added to the
×
10 ml), then resolved in
sulfuric acid and ammonium bromide as the catalyst for the in
situ generation of Br . To examine the oxidizing properties of
+
2
4
filtrate and filtered out after 20 min. Finally organic solvents
were evaporated and 1-(dodecylsulfinyl)dodecane was
this catalytic media, we applied this system to the oxidation of
alcohols and sulfides.
obtained as a white crystalline solid (0.383 g, 99%); m.p.: 89-
Initially, in order to find the appropriate solvent for the
oxidation of alcohols and sulfides, we designed separated
reactions for these transformations in different organic
solvents. Dibenzyl sulfide and 4-bromobenzyl alcohol were
subjected to the oxidation reaction by PVP-H O , silica
sulfuric acid and a catalytic amount of ammonium bromide in
the presence of two drops of water. The results of these
reactions are summarized in Table 1.
From the solvent screening (Table 1) acetonitrile emerged
as the most convenient one due to the fact that the products
were isolated in almost quantitative yields and shortest
reaction times. Therefore, acetonitrile was selected as the
reaction solvent for all of the oxidation reactions. Also, as is
1
9
1
0
5
1
1 ºC; H NMR (500 MHz, CDCl ): 2.70-2.57 (m, 4H), 1.70-
3
.80 (m, 4H), 1.49-1.40 (m, 4H), 1.39-1.21 (m, 32H), 0.89-
1
3
.86 (t, J = 11.5 Hz, 6H) ppm; C NMR (125 MHz, CDCl ):
3
2.5, 31.9, 29.6, 29.5, 29.3, 29.3, 29.2, 28.9, 22.6, 22.6, 22.5,
4.1 ppm.
2
2
Oxidation of 4-Bromobenzyl Alcohol into 4-
Bromobenzaldehyde Using PVP-H
Acid and Ammonium Bromide
2
O
2
, Silica Sulfuric
PVP-H O2 (0.290 g), silica sulfuric acid (0.100 g),
2
ammonium bromide (0.050 g, 0.05 mmol) and water (2 drops)
were added to a solution of 4-bromobenzyl alcohol (0.187 g, 1
1
083

Polyvinylpolypyrrolidone-Supported Hydrogen Peroxide
Table 1. Oxidation of Dibenzyl Sulfide and 4-Bromobenzyl Alcohol by PVP-H O , Silica Sulfuric Acid
2
2
a
and Ammonium Bromide in the Presence of Two Drops of Water in Different Solvents
Entry
Compound
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
Solvent/Temperature
Acetonitrile/r.t.
Acetone/r.t.
Chloroform/r.t.
Dichloromethane/r.t.
n-Hexane/r.t.
Ethyl acetate/r.t.
Ethanol/r.t.
Ethanol/60 ºC
Time (min)
90
Yield (%)b
98
1
2
3
4
5
6
7
8
9
24 h
24 h
24 h
24 h
25 h
6 h
180
195
90
80
240
90
180
200
trace
c
-
-
-
d
e
f
73
67
Sluggish
85
Sluggish
36
Acetone/60 ºC
1
1
1
1
1
0
1
2
3
4
5
Chloroform/60 ºC
n-Hexane/60 ºC
Ethyl acetate/60 ºC
Acetonitrile/60 ºC
Acetonitrile/40 ºC
Acetonitrile/rt
51
88
70
73
1
a
Substrate/PVP-H
2
O
2
/silica sulfuric acid/ammonium bromide: 1 mmol/0.290 g/0.1 g/0.05 mmol).
b
c
d
Isolated yield. Reaction didn’t complete. Reaction didn’t complete and impurity of sulfone was
e
f
observed on TLC. No reaction. GC yield.
evident from Table 1, the highest yield for the oxidation of 4-
bromobenzyl alcohol was obtained at 60 ºC; thus this
temperature was used in all alcohol oxidation reactions.
With the optimal conditions in hand, a wide variety of
sulfides 1 and alcohols 3 were selectively oxidized into
theircorresponding sulfoxides 2 and aldehydes or ketones 4
using polyvinylpolypyrrolidone-supported hydrogen peroxide
H
C
2
H
C
N
OH
CH
O
C
O
.H O
2
2
R1
R2
n
R1
R2
Silica sulfuric acid
NH Br, CH CN, 60 °C
4
3
1
2
H
C
2
H
C
N
O
S
(
PVP-H
2
2
O ), silica sulfuric acid and catalytic amounts of
O
.H O
2
2
S
ammonium bromide at appropriate temperature (Scheme 1 and
Table 2).
R1
R2
R1
R2
n
Silica sulfuric acid
NH Br, CH CN, rt
4
3
3
4
Sulfoxidation and oxidation of alcohols heterogeneously
proceeded under mild conditions. Oxidation of sulfides was
readily carried out via mixing of a sulfide with PVP-H O ,
Scheme 1. Catalytic oxidation of alcohols and sulfides
2
2
silica sulfuric acid, catalytic amounts of ammonium bromide
and two drops of water and stirring of this mixture at room
temperature for the appropriate time. The pure product was
obtained easily by filtration and evaporation of the organic
solvent. On the other hand, the oxidation of alcohols was
performed by the same mixture at 60 ºC. After the completion
of the reaction, the corresponding aldehyde or ketone was
easily obtained by passing the reaction mixture through a
short column.
In order to prove the catalytic role of ammonium bromide
in the described oxidizing systems, dibenzyl sulfide and 4-
bromobenzyl alcohol (as typical examples) were subjected to
1
084

Ghorbani-Choghamarani & Azadi
Table 2. Oxidation of Sulfides and Alcohols into Sulfoxides and Carbonyl Compounds, Respectively, Using PVP-H
2
2
O ,
Silica Sulfuric Acid and Catalytic Amounts of NH Br in the Presence of Two Drops of Water
4
Substrate/Reagents/Catalyst b
Entry
Substrate
Product
Time (min) Yield (%)c
I
II
III
O
S
S
1
2
0.44
0.2
0.15
170
110
98
91
O
S
S
0.29
0.1
0.05
3
4
S
S
O
0.29
0.29
0.1
0.1
0.05
-
90
98
S
S
O
48 h
95d
O
S
S
5
6
0.29
0.29
0.1
0.1
0.05
0.05
90
75
99
97
O
S
S
Cl
Cl
7
8
S
S
O
0.29
0.29
0.1
0.1
0.05
0.05
45
90
96
99
O
S
C H
11 23
S
11 23
C H
C
11
H
23
C11H23
9
O
S
0.29
0.29
0.1
0.1
0.05
0.05
30
83
93
S
O
S
S
1
1
0
1
160
OH
OH
O
S
S
0.29
0.29
0.1
0.1
0.05
0.05
105
20
98
89
1
2
S
S
O
O
S
1
1
3
4
0.29
0.29
0.1
0.1
0.05
0.05
70
45
95
99
S
OH
OH
O
S
S
1
5
Cl
CH OH
2
Cl
CHO
0.29
0.1
0.05
120
81
1
085

Polyvinylpolypyrrolidone-Supported Hydrogen Peroxide
Table 2. Continued
1
1
1
6
7
8
Br
Br
F
CH
CH
2
2
OH
OH
Br
Br
F
CHO
CHO
CHO
0.29
0.29
0.29
0.1
0.1
0.1
0.05
-
90
88
Traced
93
300
180
CH
2
OH
0.05
F
F
1
2
2
9
0
1
0.29
0.29
0.29
0.1
0.1
0.1
0.05
0.05
0.05
180
120
120
90
80
94
CH OH
CHO
2
CH OH
CHO
2
Cl
Cl
Cl
F
CH OH
Cl
F
CHO
2
Cl
Cl
F
F
F
F
2
2
CH
2
OH
CHO
0.29
0.1
0.05
180
Trace
F
F
F
F
OH
O
2
2
3
4
0.29
0.29
0.1
0.1
0.05
0.05
140
70
94
95
OH
O
Cl
Cl
2
2
2
5
6
7
CH
2
OH
CHO
CHO
0.29
0.29
0.29
0.1
0.1
0.1
0.05
0.05
0.05
120
90
88
86
45
CH OH
2
120
CH OH
CHO
2
O
O
2
8
0.29
0.1
0.05
270
N.R.
N
CH OH
2
N
CHO
a
b
Oxidation of alcohols proceeded at 60 ºC and oxidation of sulfides carried out at room temperature. I and II refer to
c
d
grams of PVP-H O and silica sulfuric acid, respectively; III refer to mmol of NH Br. Isolated yield. Reaction
2
2
4
proceeded in the absence of catalyst.
1
086

Ghorbani-Choghamarani & Azadi
H
C
2
H
C
N
the oxidation reaction in the absence of the catalyst. As is
O
.H
2 2
O
evident from Table 2 (Entry 18), trace conversion of 4-
bromobenzaldehyde was observed after 5 h. Also reaction
time for the oxidation of dibenzyl sulfide increased from 1.5
hours to 48 h (Table 2 and entry 4).
To investigate and develop the scope and limitation of the
oxidizing media, we decided to examine different solid acids,
instead of silica sulfuric acid, in the described oxidizing
system (Scheme 2 and Table 3).
S
S
O
n
Solid acid
NH
4
3
Br, CH CN, rt
H
C
2
H
C
N
CH
2
OH
CHO
Br
O
.H O
2 2
n
Solid acid
Br, CH CN, 60 °C
NH
4
3
Br
As is evident from Table 3, a variety of solid acids bring
about this transformation as silica sulfuric acid does in this
oxidizing system. In order to investigate the role of solid acids
in the described systems, dibenzyl sulfide and 4-bromobenzyl
alcohol were subjected to the oxidation in the absence of any
Solid acid: Zn(HSO
4
)
2
, Zr(HSO
4
)
2
, Ca HSO
4
)
2
, K HSO
4
, NaHSO ,
4
Fe(HSO ) , Al(HSO ) , L-Alanine, NH SO H or Citric
4
3
4
3
2
3
acid
Scheme 2. Oxidation of dibenzyl sulphide and 4-bromobenzyl
alcohol in the presence of different solid acids
Table 3. Oxidation of Dibenzyl Sulfide and 4-Bromobenzyl Alcohol with PVP-H O , Solid Acid,
2
2
a
Two Drops of Water and Catalytic Amounts of NH Br
4
Entry
Compound
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
Dibenzyl sulfide
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
4-Bromobenzyl alcohol
Solid acid
Zn(HSO4)2
Zr(HSO4)4
Ca(HSO4)2
KHSO4
Time (min)
22 h
50
Yield (%)b
1
2
3
4
5
6
7
8
9
88
99
98
98
99
65
130
230
200
55
24 h
24 h
48 h
240
140
100
70
200
300
120
140
300
300
300
NaHSO
4
Fe(HSO
Al(HSO
4
)
)
3
98
98
4
3
L-Alanine
NH SO H
N.R.
Trace
98
c
2
3
1
1
1
1
1
1
1
1
1
1
2
2
0
1
2
3
4
5
6
7
8
9
0
1
2
Citric acid
-
Zn(HSO4)2
Zr(HSO4)4
N.R.
61
Sluggish
Ca(HSO
KHSO
4
)
2
83
77
67
82
85
4
NaHSO
4
Fe(HSO4)3
Al(HSO4)3
L-Alanine
NH SO H
c
Trace
76
74
2
3
Citric acid
-
2
240
N.R.
a
b
c
Substrate:PVP-H
absence of acid.
2
O
2
:acid:NH
4
Br = 1 mmol:0.290 g:0.5 mmol:0.05 mmol. Isolated yield. In the
1
087

Polyvinylpolypyrrolidone-Supported Hydrogen Peroxide
acid; surprisingly it was observed that no reactions occurred
mechanism for these transformations has been outlined in
Scheme 4 based on the previously reported works [43-47].
Initially, the combination of polyvinylpolypyrrolidone-
after 4 h (Table 3, entries 11 and 22), which means that the
presence of acid is necessary for these transformations.
One of the outstanding advantages of these oxidizing
systems is the selectivity and chemoselectivity in several
cases, which is outlined in Scheme 3. The suggested
supported hydrogen peroxide (PVP-H
2
2
O ) and silica sulphuric
acid react with ammonium bromide to produce hypobromous
acid (BrOH). Finally, hypobromous acid oxidizes alcohol or
O
S
O
O
S
A
S
+
8
0-99 %
0%
O
S
S
S
A
OH
OH +
O
9
3 %
0%
O
S
A
S
S
OH
OH +
S
O
9
5 %
0%
O
S
O
S
A
+
9
9 %
0%
B
Br
CH
2
OH +
CH
2
CH
2
OH
Br
CHO +
CH
2
CHO
88 %
Trace
B
CHO +
CH OH
+
2
O
N
CHO
O
N
2
CH OH
4
5 %
0%
A= PVP-H O (0.29 g), Silica sulfuric acid (0.1 g), NH Br (0.05 mmol), H O (2 drops), CH CN, r.t.
2
2
2
2
4
4
2
2
3
3
B= PVP-H O (0.29 g), Silica sulfuric acid (0.1 g), NH Br (0.05 mmol), H O (2 drops),CH CN, 60 °C
Scheme 3. Selectivity in the oxidation of alcohols and sulfides
H
C
2
H
C
N
O
O
S
C
O
.H
2
O
2
NH Br
4
or
SiO -OSO H +
2
3
n
H
C
2
H
C
N
OH
CH
O
BrOH
SiO
2
-OSO
3
NH
4
+
+
H
2
O
S
n
or
Scheme 4. Mechanism of the oxidation reaction of alcohols and sulfides
1
088

Ghorbani-Choghamarani & Azadi
sulfide in the presence of water.
In conclusion, the chemistry of polyvinylpolypyrrolidone-
supported hydrogen peroxide (PVP-H ) has opened up a
Lett. 49 (2008) 80.
[15] M. Al-Hashimi, E. Fisset, A.C. Sullivan, J.R.H. Wilson,
Tetrahedron Lett. 47 (2006) 8017.
2
O
2
new methodological option for the catalytic, versatile and
efficient oxidation of various types of sulfides and alcohols.
Characteristics such as short reaction time, metal-free content,
good reaction yields, no environmental pollution, and simple
workup procedure make this method an excellent alternative to
the oxidation of the sulfides into sulfoxides.
[16] R. Das, D. Chakraborty, Synthesis (2011) 277.
[17] Y.C. Jeong, D.J. Ahn, W.S. Lee, S.H. Lee, K.H. Ahn,
Bull. Korean Chem. Soc. 32 (2011) 1063.
[18] G.P. Romanelli, P.I. Villabrille, C.V. Caceres, P.G.
Vazquez, P. Tundo, Catal. Commun. 12 (2011) 726.
[19] T. Tsuchimoto, M. Igarashi, K. Aoki, Chem. Eur. J. 16
(
2010) 8975.
ACKNOWLEDGMENTS
[20] A.R. Karimi, R. Pashazadeh, Synthesis (2010) 437.
[
21] P. Salehi, M. Dabiri, M.A. Zolfigol, M. Baghbanzadeh,
Synlett (2005) 1155.
We gratefully acknowledge the financial support we
received from the Research Council of Ilam University, Ilam,
Iran, to carry out this research project.
[22] X.L. Wang, G.D. Wu, W. Wei, Y.H. Sun, Transition
Met. Chem. 35 (2010) 213.
[
23] A. Shokrolahi, A. Zali, M.H. Keshavarz, Chin. Chem.
Lett. 19 (2008) 1274.
REFERENCES
[
24] Z.T. Du, J.P. Ma, H. Ma, M. Wang, Y.Z. Huang, J. Xu,
Catal. Commun. 11 (2010) 732.
[
[
1]
2]
A. Solinas, M. Taddei, Synthesis (2007) 2409.
A. Ghorbani-Choghamarani, M. Nikoorazm,
[25] H.T. Cao, R. Gree, Tetrahedron Lett. 50 (2009) 1493.
[26] P.K. Tandon, P.B. Dwivedi, S. Singh, Synthetic
Commun. 39 (2009) 1920.
Goudarziafshar, H.L. Shiri, Z. Chenani, Bull. Korean
Chem. Soc. 30 (2009) 972.
[
3]
C. Evangelisti, N. Panziera, P. Pertici, G. Vitulli, P.
Salvadori, C. Battocchio, G. Polzonetti, J. Catal. 262
[27] J.C. van der Toorn, G. Kemperman, R.A. Sheldon,
I.W.C.E. Arends, J. Org. Chem. 74 (2009) 3085.
[28] S.K. Hanson, R.L. Wu, L.A. Silks, Org. Lett. 13 (2011)
1908.
[29] X.Y. Zhang, Y.Y. Qu, Y.Y. Wang, X.S. Fan, Chin.
Chem. Lett. 22 (2011) 268.
(
2009) 287.
[
[
4]
5]
E. Gonthier, R. Breinbauer, Mol. Divers. 9 (2009) 51.
S.K. Karmee, L. Greiner, A. Kraynov, T.E. Muller, B.
Niemeijera, W. Leitner, Chem. Commun. 46 (2010)
6
705.
[30] S.P. Mardur, G.S. Gokavi, J. Iran. Chem. Soc. 7 (2010)
441.
[31] B. Karimi, D. Zareyee, J. Iran. Chem. Soc. 5 (2008)
S103.
[32] Y. Ding, W. Zhao, B.C. Ma, W.Y. Qiu, Can. J. Chem.
89 (2011) 13.
[33] M.M. Lakouraj, V. Hasantabar, Asian J. Chem. 23
(2011) 919.
[34] A. Hasaninejad, M.A. Zolfigol, G. Chehardoli, M.
Mokhlesi, J. Serb. Chem. Soc. 75 (2010) 307.
[35] M.A. Zolfigol, P. Salehi, S.E. Mallakpour, M. Torabi,
Bul. Chem. Soc. Japan 76 (2003) 1673.
[
[
6]
7]
M.C. Carreno, G. Hernandez-Torres, A. Urbano, F.
Colobert, Eur. J. Org. Chem. (2008) 2035.
S. Naito, M. Nishimura, H. Yoshtsugu, H. Nogawa,
Biol. Pharm. Bull. 22 (1999) 1391.
M.C. Carreno, Chem. Rev. 95 (1995) 1717.
E.N. Prilezhaeva, Russ. Chem. Rev. 70 (2001) 897.
[
[
[
[
8]
9]
10] N. Fukuda, T. Ikemoto, J. Org. Chem. 75 (2010) 4629.
11] A. Rostami, J. Akradi, Tetrahedron Lett. 51 (2010)
3
501.
[
[
[
12] C.K. Jin, Y.M.A. Yamada, Y. Uozumi, Bull. Korean
Chem. Soc. 31 (2010) 547.
13] A.R. Hajipour, A.E. Ruoho, J. Iran. Chem. Soc. 1
[36] G. Chehardoli, M.A. Zolfigol, Phosphorus Sulfur
Silicon Relat. Elem. 185 (2010) 193.
[37] A.R. Pourali, M. Ghanel, Chin. J. Chem. 24 (2006)
(
2004) 159.
14] J.N. Moorthy, N. Singhal, K. Senapati, Tetrahedron
1
089

Polyvinylpolypyrrolidone-Supported Hydrogen Peroxide
1
077.
38] A.R. Pourali, M. Ghanei, Bull. Korean Chem. Soc. 27
2006) 1674.
Hajjami, K. Darvishi L. Gholamnia, Collect. Czech.
Chem. Commun. 75 (2010) 607.
[
[
(
[43] A. Ghorbani-Choghamarani, H. Goudarziafshar, M.
Nikoorazm, S. Yousefi, Lett. Org. Chem. 6 (2009) 335.
[44] A. Ghorbani-Choghamarani, M.A. Zolfigol, R. Ayazi-
nasrabadi, J. Braz. Chem. Soc. 21 (2010) 33.
[45] A. Ghorbani-Choghamarani, J. Zeinivand, J. Iran.
Chem. Soc. 7 (2010) 190.
[46] A. Ghorbani-Choghamarani, S. Rezaei, J. Chin. Chem.
Soc. 56 (2009) 251.
[47] A. Ghorbani-Choghamarani, P. Zamani, J. Iran. Chem.
Soc. 8 (2011) 142.
39] A. Ghorbani-Choghamarani, M. Nikoorazm, H.
Goudarziafshar, L. Shiri, Z. Chenani, Bull. Korean
Chem. Soc. 30 (2009) 972.
40] M.A. Zolfigol, K. Amani, A. Ghorbani-Choghamarani,
M. Hajjami, R. Ayazi-Nasrabadi, S. Jafari, Catal.
Commun. 9 (2008) 1739.
41] A.
Mallakpour, Synthetic Commun. 39 (2009) 4264.
42] A. Ghorbani-Choghamarani, M.A. Zolfigol, M.
[
[
Ghorbani-Choghamarani,
Z.
Chenani,
S.
[
1
090