8336
M. H. Habibi et al. / Tetrahedron 57 $2001) 8333±8337
+as a radical scavenger) in the reaction of alcohols with ethyl
formate in the presence of K CoW O ´3H O.
silica gel using petroleum ether as an eluent. 1-Heptyl
acetate was obtained as a liquid in 98% yield.
5
12 40
2
4.3. Typical procedure for acetylation of alcohols with
K CoW12O40´3H O in ethyl acetate
5 2
3. Conclusion
We have shown that ef®cient acetylation and formylation of
alcohols are promoted by a cheap, recyclable and easily
prepared potassium dodecatungstocobaltate trihydrate
To a solution of 1-butanol +1 mmol, 74 mg) in ethyl acetate
+2 mL) was added K O +0.05 mmol, 160
CoW12O40´3H
5 2
mg). The reaction mixture was stirred for 2 h at re¯ux.
The progress of reaction was monitored by GC. Ethyl
acetate was removed under reduced pressure and ether
+20 mL) was added. Evaporation of the organic solution
was followed by column chromatography on a short column
of silica gel using petroleum ether as an eluent. 1-Butyl
acetate was obtained as a liquid in 92% yield.
+
K CoW O ´3H O). This method could be useful for
5 12 40 2
ef®cient esteri®cation of acetic acid, and for the acetylation
and formylation of alcohols, which are often required in
complex synthetic schemes. The possibility of performing
the reaction in ethyl acetate or ethyl formate, the high
stereospeci®city of the reaction of +2)-menthol in both
the acetylation and formylation reactions, and the simple
procedure and work up makes this method a useful addition
to the present methodologies.
4.4. Typical procedure for formylation of alcohols with
K CoW O ´3H O in ethyl formate
5
12 40
2
1-Octanol +1 mmol, 130 mg) and K CoW O ´3H O
5 12 40 2
+
+
0.01 mmol, 32 mg) were mixed together in ethyl formate
2 mL). The reaction mixture was stirred for 30 min. at
4. Experimental
re¯ux. The progress of the reaction was monitored by GC.
The solution was evaporated under reduced pressure and
ether +30 mL) was added. The mixture was washed with
All of the products were characterized by a comparison of
their spectral and physical data with those of known
4
4±46
samples.
All yields refer to isolated products. NMR
water and dried with Na SO . Evaporation of organic
4
spectra were recorded on a Bruker AW 80 MHz. IR spectra
were run on a Shimadzu IR-435 spectrophotometer. Mass
spectra were recorded on an AMD 604 spectrometer,
EI-mode at 70 eV, FT-mode at 0.005 V. The purity of the
substances and the progress of the reactions were monitored
by TLC on silica gel or by a ShimadzuGas Chromatograph
GC-16A instrument with a ¯ame ionization detector.
2
solution was followed by column chromatography on a
short column of silica gel using petroleum ether as an eluent.
1-Octyl formate was obtained as a colorless liquid in 95%
yield.
Acknowledgements
4
.1. Preparation of the catalyst3
7;47±50
We are grateful to Isfahan University Research Council for
nancial support of this work.
®
The synthesis of potassium dodecatungstocobaltate tri-
hydrate +K CoW O ´3H O) starts with the preparation of
5
12 40
2
sodium tungstodicobalt+II)ate from cobaltous acetate +2.5 g,
.01 mol) and sodium tungstate +19.8 g, 0.06 mol) in acetic
References
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1
. +a) Zhdanov, R. I.; Zhenodarova, S. M. Synthesis 1975, 222.
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+
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. +a) Ho¯e, G.; Steglich, V.; Vorbruggen, H. Angew. Chem., Int.
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1
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4
5
12 40
2
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5
12 40
2
5
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5
12 40
2
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5
12 40
2
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aqueous solution of NaHCO , then washed with water and
3
dried +Na SO ). Evaporation of the organic solution was
4
followed by column chromatography on a short column of
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2