Oxidation of benzyl alcohols by semi-stoichiometric amounts of cobalt-doped birnessite-type layered MnO2 under oxygen atmosphere

Article abstract of DOI:10.1039/c2ra22117a

Semi-stoichiometric oxidation of benzylic alcohols to benzaldehydes was readily achieved in heated toluene in the presence of cobalt-doped birnessite MnO₂ under oxygen atmosphere. The oxidation took place selectively for benzylic alcohols, while allylic alcohols were oxidized slowly. No oxidation occurred for usual primary and secondary alcohols. Oxygen atmosphere was important to perform effective oxidation; i.e. the oxidation progressed much slower in nitrogen atmosphere. Cobalt-doped birnessite was the best catalyst for the oxidation, in which the amount of birnessite was reduced to 0.7 equivalent of alcohol, resulting in yields of aldehydes greater than 80%. The present method provides a useful green oxidation for benzylic alcohols.

Full text of DOI:10.1039/c2ra22117a

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Oxidation of benzyl alcohols by semi-stoichiometric
amounts of cobalt-doped birnessite-type layered MnO2
under oxygen atmosphere3
Cite this: RSC Advances, 2013, 3, 468
a
a
b
b
Akio Kamimura,* Yuichiro Nozaki, Mai Nishiyama and Masaharu Nakayama*
Semi-stoichiometric oxidation of benzylic alcohols to benzaldehydes was readily achieved in heated
toluene in the presence of cobalt-doped birnessite MnO under oxygen atmosphere. The oxidation took
2
place selectively for benzylic alcohols, while allylic alcohols were oxidized slowly. No oxidation occurred for
usual primary and secondary alcohols. Oxygen atmosphere was important to perform effective oxidation;
i.e. the oxidation progressed much slower in nitrogen atmosphere. Cobalt-doped birnessite was the best
catalyst for the oxidation, in which the amount of birnessite was reduced to 0.7 equivalent of alcohol,
resulting in yields of aldehydes greater than 80%. The present method provides a useful green oxidation
for benzylic alcohols.
Received 11th September 2012,
Accepted 5th November 2012
DOI: 10.1039/c2ra22117a
www.rsc.org/advances
1
1
tion of benzylic and allylic alcohols, where birnessite was
prepared by only calcining KMnO and its interlayer was
Introduction
4
Oxidation is one of the most important reactions in organic
+
12
occupied with K ions. However, a large excess amount of
birnessite was necessary to achieve efficient oxidation. In the
course of our research program in developing new reagents,
1
synthesis. The conversion of primary alcohols to aldehydes is
very frequently used in organic transformations. For this
purpose, good oxidation reagents/methods have been devel-
we were interested in aerobic oxidation using undoped MnO
2
2
oped so far. For example, chromium reagents such as PCC
10g
with one-dimensional tunnels.
In this paper, we report a
new aerobic oxidation of benzylic alcohols using cobalt-doped
birnessite (Co-Bir) that was synthesized according to the sol–
3
4
5
and PDC, Swern oxidation, TPAP, Dess–Martin period-
6
7
8
9
inane, TEMPO and AZADO, and MnO
2
are typically
employed for the conversion of alcohols to aldehydes.
Among them, MnO2 is recognized as a unique oxidation
reagent because it achieves selective oxidation for benzylic and
allylic alcohols. It is also recognized as a useful reagent
because of its wide natural abundance, low-cost, and is
environmentally-friendly. However, the oxidation usually
13
gel procedure. It is generally accepted that the Co ions are
located in the MnO
2
frameworks to improve the electrical
14
conductivity of MnO
2
.
Results and discussion
2
requires large excess amounts of MnO . This is a serious
drawback for its use in green organic syntheses. Among
We first examined the oxidation of benzyl alcohol in the
presence of sub-stoichiometric amounts of calcined-birnessite
various MnO polymorphs, birnessite has attracted particular
2
1
0
attention owing to its unique catalytic properties. Birnessite
has a layered structure composed of edge-shared MnO
octahedra containing predominantly Mn cations as the
(
Scheme 1). The results are summarized in Table 1.
Treatment of 1a with calcined-birnessite (0.3 g mmol of
a) under nitrogen atmosphere at room temperature did not
6
21
4
+
1
4
+
3+
center ions. Some of the Mn ions are replaced with Mn
undergo efficient oxidation; i.e. benzaldehyde 2a was obtained
in only 20% yield (entry 1). Use of oxygen atmosphere was also
inefficient (entry 2). The oxidation progressed at elevated
ions, giving a net negative charge to be compensated by the
+
intercalation of guest cations such as K . We recently found a
sufficient activity of readily available birnessite toward oxida-
a
Department of Applied Molecular Bioscience, Graduate School of Medicine,
Yamaguchi University, Ube 75-8611, Japan. E-mail: ak10@yamaguchi-u.ac.jp;
Fax: +81 836 85 9231; Tel: +81 836 85 9231
b
Department of Material Chemistry, Graduate School of Science and Engineering,
Yamaguchi University, Ube 755-8611, Japan. E-mail: nkymm@yamaguchi-u.ac.jp;
Fax: +81 836 85 9201; Tel: +81 836 85 9223
3
Electronic Supplementary Information (ESI) available: See DOI: 10.1039/
c2ra22117a
Scheme 1 Oxidation of benzyl alcohol 1a by calcinated-birnessite
This journal is ß The Royal Society of Chemistry 2013
4
68 | RSC Adv., 2013, 3, 468–472

View Article Online
RSC Advances
Paper
Table 1 Oxidation of benzyl alcohol 1a under various conditions
2
Table 2 Oxidation of 1a with various MnO -based oxidants
a
a
Entry
T/uC
Atmosphere
2a; Yield (%)
Entry
Oxidant
2a; Yield (%)
1
2
3
4
25
25
110
110
N
2
O
2
N
2
O
2
20
14
70
90
1
2
3
4
Fe-Bir
60
89
82
71
Co-Birb
Co-Bir
Undoped-Bir
a
a
b
GC yields.
GC yields. One tenth of Co was doped.
temperature, giving 2a in 70% yield (entry 3). Benzylalcohol 1a
underwent further smooth oxidation when treated with
calcined-birnessite under oxygen atmosphere at 110 uC (entry
Oxidation for secondary benzylic alcohol was examined
(Scheme 4). Phenylethyl alcohol underwent smooth oxidation
to give acetophenone 3a in 87% yield. The reaction rate was
almost the same as those observed for benzyl alcohols. On the
other hand, the reaction rate decreased as the steric size of R
group increased. For example, oxidation of 1-phenyl-2-methyl-
1-propanol progressed sluggishly, and only a trace amount of
3c was observed along with 93% of recovery of the starting
alcohol. Thus, the present oxidation procedure is sensitive
toward the steric effect from the side chain. For example,
treatment of a 1 : 1 mixture of benzyl alcohol 1a and
phenylpropyl alcohol under the standard reaction conditions
under oxygen atmosphere resulted in the selective oxidation of
1a, and benzaldehyde 2a and phenylethyl ketone 3b were
obtained in 85% and 3% yields, respectively.
Allylic alcohols were also converted into unsaturated
aldehydes, but the reaction rate was much slower than
benzylic alcohols (Scheme 5). The reaction was conducted
for at least 30 h for these alcohols. For example, cinnamyl
alcohol was oxidized to cinnamaldehyde 4a in 45% yield. A
similar treatment gave citral 4b in 61% yield. Saturated
alcohols were not converted to aldehyde 5a under these
conditions and the starting alcohol was recovered.
4), where no over oxidation product was detected. Since this
reaction condition seemed promising, we examined various
MnO2 materials under similar conditions (Scheme 2). The
results are summarized in Table 2.
Iron-doped birnessite (Fe-Bir) reacted with 1a to give 2a in
60% yield (entry 1). The use of Co-Bir improved the yield of 2a
to 89% (entry 2). The doping amount of cobalt affected the
efficiency of the oxidation, and the yield of 2a decreased
slightly when Co amount was reduced to 1/10 (entry 3). The
similarly-obtained undoped birnessite afforded 2a in a lower
yield (entry 4).
These results suggested that use of Co-Bir achieved effective
benzylic oxidation with smaller amounts of the oxidant.
2
Although the reduced amount of MnO led to less efficient
oxidation under room temperature conditions, heating to 110
uC under oxygen atmosphere attained sub-stoichiometric
oxidation of benzylic alcohols. This procedure was examined
for various benzylic alcohols 1 (Scheme 3). The results are
summarized in Table 3.
The oxidation progressed smoothly and gave benzaldehyde
in good yields. Surprisingly, the amounts of the oxidant could
be reduced to 30 mg per 1 mmol of benzyl alcohol without
significant loss of the efficiency although a longer reaction
time was needed for completion (entry 1). Most of benzyl
alcohols were oxidized with 67 to 110 mg per 1 mmol of benzyl
alcohol. For example, o-methylbenzylalcohol underwent oxida-
tion reaction to afford o-tolualdehyde 2b in 81% isolated yield
Scheme 3 Oxidation of benzyl alcohols 1 by cobalt-doped birnessite (Co-Bir)
Table 3 Oxidation of benzylic alcohols with Co-Bir
(
entry 4). Isolation of the products was quite easily performed;
i.e. a filtration of the reaction mixture followed by concentra-
tion provided the desired aldehyde. The reaction rates for the
benzyl alcohols substituted with an electron-donating group
were faster than that of the alcohols substituted with an
electron-withdrawing group; the oxidation for the latter
alcohols required more amounts of Co-Bir (entries 7 and 8).
2
1
a
Entry
R
Time (h) Oxidant (mg mmol
)
2;
Yield (%)
b
1
2
3
4
5
6
7
8
9
H
H
H
24
24
4
6
7
30
50
67
67
86
2a; 84
2a; 99
2a; 89
2b;
2c;
2d;
2e;
2f;
b
b
o-Me
p-Me
m-Cl
81
91
85
94
98
85
90
88
7
86
p-Cl 11
110
110
86
86
86
p-NO
o-NO
2
10
8
6
2
2g;
2h;
2i;
1
1
0
1
m-MeO
p-Br
7
a
b
Scheme 2 Oxidation of benzyl alcohol 1a by MnO
2
-based oxidant
Isolated yields. GC yields.
This journal is ß The Royal Society of Chemistry 2013
RSC Adv., 2013, 3, 468–472 | 469

View Article Online
Paper
RSC Advances
Scheme 6 Competitive reaction between benzyl alcohol and allylic alcohol
the reaction progressed in a similar mechanism to the
classical MnO2 oxidation reaction. The reaction conditions
proposed here involve a solid-liquid two-phase heterogeneous
process, where the reaction should progress only on the
surface of Co-Bir; thereby the actually effective amount of Co-
Bir in the reaction should be much smaller than the amount
applied. In other words, only a part of Co-Bir would serve as
the active oxidant. Even so, this amount of oxidant was at the
lower limit for performing effective oxidation, and less amount
of oxidant gave moderate to low yields for the aldehydes. Thus,
Scheme 4 Oxidation of secondary benzylic alcohols 2 and their competitive
reaction
As shown in Scheme 6, the competitive oxidation between
benzylic and allylic alcohols indicated that the oxidation of
benzylic alcohol was much preferred than allylic alcohol. For
example a 1 : 1 mixture of benzyl alcohol and 2-cyclohexen-1-
ol afforded a mixture of benzaldehyde and cyclohexeneone in
54 : 18.
the catalytic performance of MnO
such a high yield of aldehyde.
2
is mandatory to achieve
In order to confirm whether the present oxidation had been
promoted in the presence of Co-Bir, a leaching test was carried
out (Scheme 7). Treatment of benzyl alcohol with a semi-
catalytic amount of Co-Bir under oxygen atmosphere for 30
min resulted in the formation of benzaldehyde 2a in 34%
yield. The reaction mixture was divided into two; i.e. one was
supernatant that did not contain Co-Bir catalyst, and the other
contained the catalyst. The two mixtures were again exposed to
oxygen atmosphere and heated at 110 uC for an additional 5.5
h. The former solution was unchanged and the yield of 2a was
still 34%, while in the latter mixture the reaction progressed
and benzyl alcohol was converted to benzaldehyde completely.
This clearly shows that the oxidation requires Co-Bir. No
oxidation occurred when alcohol was heated under oxygen
atmosphere in the absence of Co-Bir.
The oxidation activity of birnessite is mainly associated
4
+
with the presence of Mn . Therefore, the oxidation of benzyl
4
+
alcohols proceeds accompanied by the reduction of Mn sites
3
+
in the oxide to Mn . The presence of oxygen can reoxidize the
3
+
4+
generated Mn sites back to Mn that is available for a new
oxidation reaction. This view can be thermodynamically
supported by the related redox reactions and their standard
0
electrode potentials (E , V vs. SHE), as shown in Scheme 8.
0
Although E values of benzylalcohols were not available in
0
literature, however, as expected from E (20.197 V) of the
1
5
ethanol/acetaldehyde couple,
they are likely sufficiently
1
6
negative than that (+0.75 V) of MnO /Mn O . This means
that electrons spontaneously move from alcohol to Mn . The
value (+1.23 V) for the O /H O couple is sufficiently positive
2
2 3
4
+
2
2
Considering the amount of Co-Bir, it is reasonable to
assume that the oxidation protocol involves catalytic char-
acteristics of MnO because the amount of Co-Bir employed in
2
compared to that (+0.75 V) of MnO
the generated Mn ions can be reoxidized to Mn by O
2
/Mn
2 3
O , confirming that
3
+
4+
2
. This
is probably the reason why the efficient oxidation occurred
under oxygen atmosphere in the presence of Co-Bir with sub-
stoichiometric amounts. We guess the present catalytic cycle is
not very good because the oxidation using less amounts of Co-
Bir only afforded aldehydes in poor yields. The turnover
number is likely just one or two. Even so the present procedure
the reaction was slightly less than the yields of aldehydes. For
example, 70 mol% of Co-Bir was used for the oxidation of
benzyl alcohol 1a and benzaldehyde 2a was obtained in 89%
yield (Table 2, entry 3). Thus, the sub-stoichiometric amount
2
of MnO achieved high yields of aldehydes. We assume that
2
achieved dramatic reduction of MnO for the oxidation of
Scheme 5 Oxidation of allylic alcohols
Scheme 7 Leaching test
4
70 | RSC Adv., 2013, 3, 468–472
This journal is ß The Royal Society of Chemistry 2013

View Article Online
RSC Advances
Paper
1
p-Chlorobenzaldehyde (2e): H NMR d
H 3
(500 MHz, CDCl ):
9
=
1
.98 (1H, s, –CHO), 7.82 (2H, dd, J = 8.5, 1.9 Hz), 7.51 (2H, dd, J
1
3
8.5, 2.1 Hz); C d
C
(126 MHz, CDCl
3
): 191.0 (–CHO), 141.1,
(500 MHz, CDCl ):
34.8, 131.0, 129.6.
p-Nitrobenzaldehyde (2f): H NMR d
1
H
3
1
0.15 (1H, s, –CHO), 8.39 (2H, d, J = 8.7 Hz), 8.07 (2H, d, J = 8.8
1
3
Hz); C d
C
3
(126 MHz, CDCl ): 190.4 (–CHO), 140.1, 130.6,
1
24.4.
1
o-Nitrobenzaldehyde (2g): H NMR d
H 3
(500 MHz, CDCl ):
1
0.43 (1H, s, –CHO), 8.12 (1H, dd, J = 7.9, 1.2 Hz), 7.96 (1H, dd,
1
3
J = 7.4, 1.8 Hz), 7.85–7.75 (2H, (m); C d
C
(126 MHz, CDCl
3
):
1
88.3 (–CHO), 134.2, 133.8, 131.5, 129.7, 124.6.
1
H 3
m-Anisaldehyde (2h): H NMR d (500 MHz, CDCl
): 9.96
(
7
1
1H, s, –CHO), 7.47–7.40 (2H, (m), 7.40–7.35 (1H, (m), 7.19–
.13 (1H, (m), 3.84 (3 H, s, –OCH3); C d (126 MHz, CDCl ):
C 3
Scheme 8 A possible spontaneous process on the basis of thermodynamic data
1
3
92.3 (–CHO), 160.2, 137.9, 130.1, 123.6, 121.6, 112.1, 55.6
).
p-Bromobenzaldehyde (2i): H NMR d
.98 (1H, s, –CHO), 7.75 (2H, d, J = 8.3 Hz), 7.69 (2H, d, J = 8.5
(OCH
3
1
3
(500 MHz, CDCl ):
benzylic alcohol and it will provide a sustainable method for
organic synthesis.
H
9
1
3
Hz); C d
31.0, 129.8.
C
3
(126 MHz, CDCl ): 191.2 (–CHO), 135.2, 132.5,
1
1
Acetophenone (3a): H NMR d (500 MHz, CDCl ): 7.95 (2H,
H
3
Experimental
dd, J = 8.3, 1.2 Hz), 7.56 (1H, t, J = 7.4 Hz), 7.46 (2H, t, J = 7.7
1
3
Hz), 2.60 (3H, s, PhCOCH
3
); C d
C
(126 MHz, CDCl
).
(500 MHz, CDCl
2H, d, J = 7.2 Hz), 7.55 (1H, t, J = 7.4 Hz), 7.45 (2H, t, J = 7.7
CH ), 1.22 (3H, t, J = 7.2 Hz, –
CH CH ); C d (126 MHz, CDCl ): 201.0 (CLO), 137.0, 133.0,
3
): 198.3
Preparation of Co-doped birnessite (Co-Bir)
(CLO), 137.2, 133.2, 128.7, 128.4, 26.7 (CH
3
Co-doped birnessite (Co-Bir) was prepared by a modified so-gel
1
Propiophenone (3b): H NMR d
H
3
): 7.96
1
3
method according to the literature. A 50 mL of CoSO
4
(
2
1
solution at a concentration of 0.038 or 0.0038 mol L was
mixed to a solution containing 0.028 moles of glucose. The
resulting mixture was added quickly to a solution with 0.019
Hz), 3.01 (2H, q, J = 7.2 Hz, –CH
2
3
13
2
3
C
3
1
28.7, 128.1, 31.9 (CH ), 8.3 (CH ).
2 3
4
moles of KMnO under vigorous stirring. The molar ratios of
1
Cinnamaldehyde (4a): H NMR d (500 MHz, CDCl ): 9.70
H
3
Co to Mn were 0.1 and 0.01. The obtained brown gel was
cooled at room temperature and then dried at 110 uC
overnight. The product was calcined at 400 uC for 2 h, washed
thoroughly with water, and then dried at 110 uC overnight.
(1H, d, J = 7.7 Hz, –CHO), 7.58–7.53 (2H, (m), 7.47 (1H, d, J =
1
7
1
6.0 Hz, –CHLCH–), 7.45–7.39 (3H, (m), 6.71 (1H, dd, J = 16.0,
13
.7 Hz, –CHLCH–); C d
C 3
(126 MHz, CDCl ): 193.8 (CHO),
52.9, 134.1, 131.4, 129.2 (CLC), 128.7, 128.6 (CLC).
1
Oxidation of benzyl alcohols 1 to benzaldehyde 2; General
H 3
Citral (4b): H NMR d (500 MHz, CDCl ): 9.98 (1H, d, J = 8.1
procedure: Preparation of o-tolualdehyde (2b)
Hz, –CHO), 5.87 (1H, dd, J = 8.1, 1.1 Hz, LCHCHO), 5.06 (1H,
ddd, J = 6.6, 4.0, 1.3 Hz, Me CLCH–), 2.25–2.17 (4H, m,
2
A mixture of Co-Bir (67 mg) and o-methylbenzylalcohol (122.6
mg, 1.0 mmol) in toluene (10 mL) was heated at 110 uC under
oxygen atmosphere for 6 h. The reaction mixture was filtered
through celite and concentration of the filtrate gave crude
aldehyde, which was purified by Kugelrohl distillation under
LCHCH
s, (CH
CDCl
27.5
C(CH )LCHCHO), 25.8 (–CH CH –), 25.7 (–CH CH –), 17.8
2
CH
CLCH–), 1.60 (3 H, s, (CH
): 191.4 (CHO), 164.0 (–CLCHCHO), 133.0(–CLCHCHO),
(Me CLCH–), 122.6 (Me CLCH–), 40.7 (–
2
C(Me)L), 2.16 (3H, s, –C(CH
3
)LCHCHO), 1.68 (3H,
13
3
)
2
3
)
2
CLCH–); C d
C
(126 MHz,
3
1
2
2
3
2
2
2
2
reduced pressure (170 uC/0.7 mmHg) to give 2b in 81% yield
1
(CH
3
)
2 3 2
CLCH–), 17.7 (CH ) CLCH–).
(
97.7 mg). Colorlesss oil; H NMR dH (500 MHz, CDCl ): 10.28
3
(
1
1H, s, –CHO), 7.80 (1H, dd, J = 7.8, 1.1 Hz), 7.48 (1H, td, J = 7.5,
1
3
.4 Hz), 7.27 (1H, d, J = 7.6 Hz), 2.68 (3H, s, –CH3); C d (126
C
MHz, CDCl
26.5, 19.6 (–CH3).
Other compounds 2 were prepared in a similar manner.
3
): 193.0 (–CHO), 140.7, 134.3, 133.7, 132.1, 131.9,
Conclusions
1
We have successfully developed a new protocol to oxidize
benzylic alcohols using sub-stoichiometric amounts of man-
ganese oxidant. The oxidation progressed smoothly for
benzylic alcohols and chemoselectivity is very high. The
oxidation is sensitive to steric effects and less hindered
alcohols underwent selective oxidation. Use of oxygen atmo-
sphere is important, and the stoichiometry suggests that a
catalytic cycle of manganese oxide should be included in the
reaction. Indeed, the oxidation potential of manganese oxide
and molecular oxygen allows the process to progress thermo-
1
H 3
p-Tolualdehyde (2c): H NMR d (500 MHz, CDCl ): 9.96 (1H,
s, –CHO), 7.77 (2H, d, J = 8.4 Hz), 7.33 (2,H d, J = 8.6 Hz), 2.43
1
3
(
1
3H, s, –CH
3
); C d
30.0, 129.8, 21.9 (–CH
m-Chlorobenzaldehyde (2d): H NMR d
.90 (1H, s, –CHO), 7.77 (1H, t, J = 2.0 Hz), 7.68 (1H, dt, J = 7.9
C
(126 MHz, CDCl
3
): 192.2, 145.7, 134.3,
3
).
1
H
3
(500 MHz, CDCl ):
9
Hz, 1.3), 7.52 (1H, dd, J = 7.9, 2.8 Hz), 7.41 (1H, t, J = 7.8 Hz);
1
3
C 3
C d (126 MHz, CDCl ): 190.9 (–CHO), 137.9, 135.5, 134.4,
130.4, 129.3, 128.0.
This journal is ß The Royal Society of Chemistry 2013
RSC Adv., 2013, 3, 468–472 | 471

View Article Online
Paper
RSC Advances
dynamically. Conventional oxidation procedures using acti-
vated MnO require a large excess amount of manganese
2
Y. Iwabuchi, Synthesis, 2011, 3418; (e) M. Shibuya,
Y. Osada, Y. Sasano, M. Tomizawa and Y. Iwabuchi, J.
Am. Chem. Soc., 2011, 133, 6497.
(a) A. J. Fatiadi, Synthesis, 1976, 65; (b) A. J. Fatiadi,
Synthesis, 1976, 133; (c) J. Attenburrow, A. F. B. Cameron, J.
H. Chapman, R. M. Evans, B. A. Hems, A. B. A. Jansen and
T. Walker, J. Chem. Soc., 1952, 1094; (d) O. Mancera,
G. Rosenkranz and F. Sondheimer, J. Chem. Soc., 1954,
reagent. On the other hand the present protocol made
oxidation possible in sub-stoichiometric amounts of manga-
nese reagents; thus a dramatic reduction of manganese
oxidant was achieved. This provides a much greener synthetic
process in organic chemistry.
9
3
271; (e) A. R. Mattock, J. Chem. Res (S), 1977, 40; (f)
M. Harfenist, A. Bavley and W. A. Lazier, J. Org. Chem.,
954, 19, 1608; (g) S. Ball, T. W. Goodwin and R. A. Morton,
Biochem. J., 1948, 42, 516; (h) L. A. Carpino, J. Org. Chem.,
1
Acknowledgements
We are grateful for the financial support from Yamaguchi
University based on The YU Strategic Program for Fostering
Research Activities (2010–2011).
1
1
970, 35, 3971; (i) I. M. Goldman, J. Org. Chem., 1969, 34,
979; (j) J. S. Belew and C. Tek-Ling, Chem. Ind., 1967, 1958;
(k) A. J. Fatiadi, J. Chem. Soc (B), 1971, 889.
1
0 (a) J. Luo, A. Huang, S. H. Park, S. L. Suib and C. -L.
O. Young, Chem. Mater., 1998, 10, 1561; (b) O. Pietro,
M. Del Arco and V. Rives, J. Mater. Sci., 2003, 38, 2815; (c)
J. Cai and S. L. Suib, Inorg. Chem. Commun., 2001, 4, 493;
(d) D. Frias, S. Nousir, I. Barrio, M. Montes, M. A. Centeno
and J. A. Odriozola, Mater. Charact., 2007, 58, 776; (e) L.-
X. Yang, Y.-J. Zhu and G.-F. Cheng, Mater. Res. Bull., 2007,
42, 159; (f) J. Morales, L. Sanchez, S. Bach and J. P. Pereira-
Ramos, Mater. Lett., 2002, 56, 653; (g) Y.-C. Son, V.
D. Makwana, A. R. Howell and S. L.Suib, Angew. Chem.,
Int. Ed., 2001, 40, 4280.
References
1
S. D. Burke and R. L. Danheiser, Handbook of Reagents for
Organic Synthesis, Oxidizing and Reducing Agents, 1999,
John Wiley and Sons, Chichester, UK.
2
E. J. Corey and J. W. Suggs, Tetrahedron Lett., 1975, 16,
2647.
3
4
5
E. J. Corey and G. Schmidt, Tetrahedron Lett., 1979, 20, 399.
A. J. Mancuso and D. Swern, Synthesis, 1981, 165.
(a) W. P. Griffith and S. V. Ley, Aldrichimica Acta, 1990, 23,
11 A. Kamimura, Y. Nozaki, S. Ishikawa, R. Inoue and
M. Nakayama, Tetrahedron Lett., 2011, 52, 538.
12 S. Komaba, N. Kumagai and S. Chiba, Electrochim. Acta,
2000, 46, 31.
13 S. Ching, D. J. Petrovay and M. L. Jourgensen, Inorg. Chem.,
1997, 36, 883.
14 P. K. Sharma, G. J. Moore, F. Zhang, P. Zawalij and M.
S. Whittingham, Electrochem. Solid-State Lett., 1999, 2, 494.
15 P. M. Huang, Y. Li and M. E. Summer, Oxidation–Reduction
Potentials, Absorbency Bands, and Molar Absorbency of
Compounds used in Biochemical Studies, in Handbook of
Biochemistry and Molecular Biology, ed. G. Fasman,
Chemical Rubber Co., Cleveland, OH, p. 122–130.
16 B. Messaoudi, S. Joiret, M. Keddam and H. Takenouti,
Electrochim. Acta, 2001, 46, 2487.
1
3; (b) S. V. Ley, J. Norman, W. P. Griffith and S.
P. Marsden, Synthesis, 1994, 639.
(a) D. B. Dess and J. C. Martin, J. Org. Chem., 1983, 48, 4155;
6
7
8
(
2
b) R. K. Boeckman Jr., P. Shao and J. J. Mullins, Org. Synth.,
000, 77, 141.
(a) T. Vogler and A. Studer, Synthesis, 2008, 1979; (b)
G. Piancatelli and F. Leonelli, Org. Synth., 2006, 83, 18, and
references cited therein..
(a) M. Shibuya, M. Tomizawa, I. Suzuki and Y. Iwabuchi, J.
Am. Chem. Soc., 2006, 128, 8412; (b) M. Shibuya, T. Sato,
M. Tomizawa and Y. Iwabuchi, Chem. Commun., 2009,
1739; (c) M. Tomizawa, M. Shibuya and Y. Iwabuchi, Org.
Lett., 2009, 11, 1829; (d) M. Shibuya, Y. Sasano,
M. Tomizawa, T. Hamada, M. Kozawa, N. Nagahama and
4
72 | RSC Adv., 2013, 3, 468–472
This journal is ß The Royal Society of Chemistry 2013