LETTER
Oxidation of Alcohols with Benzyltriphenylphosponium Periodate
1737
Table 4 Reaction of Benzyl Alcohol under Refluxing Conditions
a
Entry
Reagent
BTPPPI
NaIO4
Solvent
Lewis acid
Time (min)
220
Yield (%)
1
CH CN
–
30
N.R
20
3
2
CH CN
–
220
3
3
NaIO4
CH CN-H O
–
220
3
2
4b
5c
6c
NaIO -BTPPPI
CH CN
–
180
10
4
3
NaIO4
CH CN
AlCl3
AlCl3
120
30
3
BTPPPI
CH CN
90
100
3
a
Monitored by TLC.
BTPPPI was used as catalytic amount (0.2 mmol).
Oxidant/Alcohol/Lewis acid (1:1:0.3).
b
c
2
20 min refluxing. In another reaction, we tried the reac- References and Notes
tion of benzyl alcohol with NaIO in the presence of a cat-
alytic amount of 1 (0.2 mmol) in refluxing acetonitrile and
the reaction proceeded in 10% yield after 3 h. We also in-
4
(
1) (a) Firouzabadi, H.; Sardarian, A. R.; Badparva, H. Bull.
Chem. Soc. Jpn. 1996, 69, 685. (b) Firouzabadi, H.;
Sardarian, A. R.; Nader, M.; Vesal, B. Tetrahedron 1984,
23, 5001. (c) Firouzabadi, H.; Baltork, I. M. Bull. Chem.
Soc. Jpn. 1992, 65, 1185. (d) Firouzabadi, H.; Mostavipoor,
Z. Bull. Chem. Soc. Jpn. 1983, 56, 914.
vestigated the use of NaIO in the presence of aluminum
4
chloride in refluxing acetonitrile and observed that the re-
action does not complete after 2 h and the corresponding
aldehyde was obtained in 30% yield. The results of these
experiments are summarized in Table 4.
(
2) Clerici, A.; Pona, O. J. Chem. Soc., Perkin Trans. 2 1988,
1234.
(
3) Fristad, W. E.; Peterson, J. R. Tetrahedron Lett. 1983, 4547.
This observation is in contrast to what is reported by us for
(4) Perumal, P. T. Synth. Commun. 1990, 20, 1353.
(
5) (a) Itahara, T.; Ebihara, R.; Fujii, Y.; Toda, M. Chem. Lett.
1986, 1319. (b) Itahara, T.; Fujii, Y.; Toda, M. J. Org.
Chem. 1988, 53, 3421.
1
-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane dichromate,
1
0
which decomposes upon standing in solution. The sta-
bility of this reagent in comparison with 1-benzyl-4-aza-
(6) (a) Yamasaki, S.; Yamasaki, Y. Bull. Chem. Soc. Jpn. 1990,
1
-azoniabicyclo[2.2.2]octane dichromate is the reflection
6
3, 301. (b) Yamasaki, S. Chem. Lett. 1992, 823.
c) Yamasaki, S.; Yamasaki, Y. Chem. Lett. 1990, 571.
(7) Juung, J. C.; Choi, H. C.; Kim, Y. H. Tetrahedron Lett. 1993,
4, 3581.
of the presence of the phosphonium cation in the reagent,
which is more stable than ammonium cation.
(
3
In summary, we report here the preparation of benzylt-
riphenylphosphonium periodate 1 as a mild, inexpensive
and stable oxidizing reagent. This oxidizing reagent is
easily prepared from commercially available starting ma-
terials and could be stored for months without losing its
activity. The reagent is soluble in acetonitrile, chloroform,
dichloromethane, dimethylformamide and ethyl acetate,
and insoluble in carbon tetrachloride, ether and hexane.
This compound is an efficient and novel reagent for oxi-
dation of benzylic and aliphatic alcohols to the corre-
sponding carbonyl compounds under non-aqueous
conditions in the presence of catalytic amounts of AlCl3.
The reactivity of benzylic alcohols with this oxidizing
agent is higher than aliphatic alcohols.
(
(
8) Choi, H. C.; Kim, Y. H. Synth. Commun. 1994, 24, 2307.
9) (a) Baltork, I. M.; Hajipour, A. R.; Mohammadi, H. Bull.
Chem. Soc. Jpn. 1998, 71, 1649. (b) Hajipour, A. R.;
Mahboobkhah, N. Synth. Commun. 1998, 28, 3143.
(c) Hajipour, A. R.; Mahboobkhah, N. Indian J. Chem. 1998,
37B, 285. (d) Hajipour, A. R.; Mahboobkhah, N. J. Chem.
Res., Synop 1998, 122. (e) Hajipour, A. R.; Mahboobkhah,
N. Indian J. Chem. 1998, 37B, 1041. (f) Hajipour, A. R.;
Baltork, I. M.; Kianfar, G. Bull. Chem. Soc. Jpn. 1998, 71,
2655. (g) Hajipour, A. R.; Baltork, I. M.; Kianfar, G. Indian
J. Chem. 1998, 37B, 607. (h) Hajipour, A. R.;
Mahboobkhah, N. Org. Prep. Proced. Int. 1999, 31, 112.
(i) Hajipour, A. R.; Baltork, I. M.; Niknam, K. Org. Prep.
Proced. Int. 1999, 31, 335. (j) Baltork, I. M.; Hajipour, A.
R.; Haddadi, R. J. Chem. Res., Synop 1999, 102.
(k) Hajipour, A. R.; Mallakpour, S. E.; Imanzadeh, G. Chem.
Lett. 1999, 99. (l) Hajipour, A. R.; Mallakpour, S. E.; Adibi,
H. Chem. Lett. 2000, 460.
10) (a) Hajipour, A. R.; Mallakpour, S. E.; Baltork, I. M.; Khoee,
S. Chem. Lett. 2000, 120. (b) Hajipour, A. R.; Mallakpour,
S. E.; Khoee, S. Synlett 2000, 740.
Acknowledgement
(
We are thankful to Research Council of the Isfahan University of
Technology (IUT) for the partial support of this work.
(
(
11) Aldrich, Handbook of fine chemicals and fine laboratory
equipment, 2000-2001.
12) Preparation of Benzyltriphenylphosphonium
Periodate(1). A solution of benzyltriphenylphosphonium
chloride (10.3 g, 26 mmol) in 50 mL of water was prepared,
then NaIO (5.56 g, 26 mmol) in water (50 mL) was added
4
Synlett 2001, No. 11, 1735–1738 ISSN 0936-5214 © Thieme Stuttgart · New York