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DOI: 10.1002/cctc.201300200
Simple and Efficient 1,3-Isomerization of Allylic Alcohols
using a Supported Monomeric Vanadium-Oxide Catalyst
[
a]
[a]
[a]
[a]
Takato Mitsudome, Shoichiro Sueoka, Satoshi Ikeda, Tomoo Mizugaki,
[
a]
[a, b]
Koichiro Jitsukawa, and Kiyotomi Kaneda*
The catalytic isomerization of allylic alcohols by the 1,3-trans-
position of a hydroxy group is an important reaction in organic
The V/SiO catalyst was prepared according to an impregna-
2
[17]
tion method. SiO (3.0 g) was added to an aqueous solution
2
[
1,2]
synthesis.
This isomerization has been applied to the indus-
of NH VO (8.4 mm). The mixture was stirred at 808C for 2 h,
4
3
trial production of terpene alcohols, such as geraniol and nerol
from linalool. In early studies, the isomerization of allylic alco-
hols was accomplished by using metal-oxo catalysts, such as
followed by evaporation of the water. The obtained slurry was
dried overnight at 1108C and subsequently calcined under
a flow of dry air at 5008C for 5 h to afford V/SiO (V: 1.4 wt.%).
2
[
3]
[4]
trialkyl vanadates and tungsten-oxo complexes, operating
V/SiO2 was characterized by X-ray absorption fine structure
(XAFS) spectroscopy. The V K-edge X-ray absorption near-edge
at high temperatures (>1308C). Since then, some improve-
[
5–14]
ments in the catalytic efficiency have been reported.
How-
structure (XANES) spectrum of V/SiO exhibited an absorption
2
5
+
ever, these catalytic systems have a variety of associated prob-
edge at 5480 eV, which was assigned to V species (see the
[
10]
[18]
lems, including the decomposition of the catalyst, the forma-
Supporting Information, Figure S1).
The spectrum also
[
11,12]
tion of byproducts,
the requirement for the addition of ac-
showed a strong pre-edge peak, which was more intense than
that of V O yet weaker than that of Na VO , thus suggesting
[
5,6,10]
[6–9,11,12]
tivators,
or use of precious metals
and their difficul-
2
5
3
4
ty in recycling the catalysts.
that the V species in V/SiO adopted a distorted tetrahedral
2
[19,20]
Heterogeneous catalysts have numerous advantages over
homogeneous catalysts in terms of their durability and their
facile separation from the reaction mixture and subsequent re-
usability, as well as their applicability in packed column reac-
tors and multi-step flow reactors. However, despite these ad-
vantages, few efficient heterogeneous catalysts have been de-
veloped for the 1,3-isomerization of allylic alcohols. The at-
tempted heterogenization of a formerly homogeneous active
tungsten species by using polyvinyl pyridine as a support has
been reported, but was unsuccessful owing to decomposition
structure.
The diffuse-reflectance UV/Vis spectrum of V/
SiO2 showed a charge-transfer band at about 250–300 nm,
which was assigned to monomeric tetrahedral VO species (see
4
[21]
the Supporting Information, Figure S2). The Raman spectrum
À1
showed a peak at 1040 cm , which was attributed to the V=O
stretching vibration (see the Supporting Information, Fig-
[22]
ure S3). These results indicate that vanadium is present on
the SiO surface as a monomeric vanadium-oxo species with
2
a distorted tetrahedral structure, which is in good agreement
[21]
with previous results reported by Tanaka and co-workers.
[
4]
of the polymer and leaching of the active metal. Thus far,
there has only been one report of an effective heterogeneous
catalytic system, which was based on the use of polymer-
Initially, we examined the catalytic activity of V/SiO for the
2
1,3-isomerization of a-vinylbenzyl alcohol (1) in MeCN at room
[23]
temperature. Interestingly, V/SiO exhibited pronounced cat-
2
[
15]
bound vanadyl phosphate (PhosphonicS POVO).
alytic activity, thereby affording cinnamyl alcohol (2) in 73%
yield with no byproducts (Table 1, entry 1). A longer reaction
time further increased the yield of 2 to 95% (Table 1, entry 2).
In sharp contrast to these results, the use of supported vanadi-
Herein, we report the use of silica-supported monomeric va-
nadium-oxo species (V/SiO ) to effectively promote the isomer-
2
ization of various allylic alcohols under mild reaction condi-
[
16]
[24]
tions, without the addition of any activators. The V/SiO cata-
um species V/Al O , V/TiO , and V/hydrotalcite hardly pro-
2
2
3
2
lyst can be easily prepared and is highly durable, thus exhibit-
ing excellent reusability without any loss of efficiency.
moted the isomerization (Table 1, entries 8–10). Substituting V/
SiO with the previously reported and commercially available
2
heterogeneous V catalyst PhosphonicS POVO resulted in a very
low yield of 2 (Table 1, entry 11). In addition, the use of V com-
pounds V O and VO(acac) , as well as the NH VO precursor
[a] Dr. T. Mitsudome, S. Sueoka, S. Ikeda, Dr. T. Mizugaki, Prof. Dr. K. Jitsukawa,
2
5
2
4
3
Prof. Dr. K. Kaneda
compound and the SiO catalyst support, all led to poor yields
2
Department of Materials Engineering Science
Graduate School of Engineering Science
Osaka University
of 2 (Table 1, entries 12–15). These results clearly demonstrate
that V/SiO has outstanding catalytic activity for the isomeriza-
2
tion reaction. Hence, the immobilization of V on the SiO sup-
1
-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)
2
Fax: (+81) 6-6850-6260
E-mail: kaneda@cheng.es.osaka-u.ac.jp
port clearly resulted in the creation of highly active vanadium
species for promoting the isomerization reaction.
[
b] Prof. Dr. K. Kaneda
Subsequently, the V/SiO catalyst was removed from the re-
2
Research Center for Solar Energy Chemistry
Osaka University
action solution by filtration once 40% conversion of 1 had
been achieved and the stirring of the filtrate was resumed
with periodic analysis of the conversion. No further conversion
was found after the removal of the catalyst, thus demonstrat-
1
-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201300200.
ꢀ
2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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