Ionic liquid brush as a highly efficient and reusable catalyst for on-water nucleophilic substitutions

Article abstract of DOI:10.1002/ejoc.201001227

A very efficient and reusable catalyst has been developed for the on-water nucleophilic substitution of alkyl halides and tosylates with azide or thiocyanate in excellent to quantitative yields. The reaction proceeds smoothly and cleanly without any organic cosolvent or other adductive, and the brush can be reused at least 10 times without noticeable loss of the catalytic activity. The high efficiency, simplicity of product and catalyst isolation, outstanding recyclability, and organic-solvent-free conditions show promise for the use of this catalyst in the laboratory and in industry. A highly efficient and reusable ionic liquid brush catalyst has been developed for the on-water nucleophilic substitution of alkyl halides and tosylates with azide or thiocyanate in excellent to quantitative yields without any organic cosolvent or other adductive. The catalyst can be reused at least 10 times without noticeable loss of the catalytic activity. Copyright

Full text of DOI:10.1002/ejoc.201001227

SHORT COMMUNICATION
DOI: 10.1002/ejoc.201001227
Ionic Liquid Brush as a Highly Efficient and Reusable Catalyst for On-Water
Nucleophilic Substitutions
Jing Li,[a] Jing-jing Cao,[a] Jun-fa Wei,*[a,b] Xian-ying Shi,[a] Li-hui Zhang,[a]
Jin-juan Feng,[a] and Zhan-guo Chen[a]
Keywords: Ionic liquids / Nucleophilic substitution / Water chemistry / Sustainable chemistry
A very efficient and reusable catalyst has been developed for
the on-water nucleophilic substitution of alkyl halides and
tosylates with azide or thiocyanate in excellent to quantita-
tive yields. The reaction proceeds smoothly and cleanly with-
out any organic cosolvent or other adductive, and the brush
can be reused at least 10 times without noticeable loss of the
catalytic activity. The high efficiency, simplicity of product
and catalyst isolation, outstanding recyclability, and organic-
solvent-free conditions show promise for the use of this cata-
lyst in the laboratory and in industry.
quids[5] bearing two or more imidazolium ions on each of
the side chains. We call them “ionic liquid brushes” because
of their brush-like feature. The brush has more imidazolium
ions per unit area and thus more counteranions, which are
exchangeable with anionic reactants or catalytic species, of-
fering a deeper 3D environment that closely resembles the
liquid-phase character of ionic liquids for both hydrophilic
and hydrophobic reactants (Figure 1). We have proved their
high efficiency and recyclability for some organic reactions
in neat water or under solvent-free conditions, such as cata-
lytic hydrogenation of nitrobenzene,[6a] dihydroxylation of
olefins with H2O2,[6b] and the Suzuki coupling reaction[6c]
Introduction
Water as a medium for organic reactions has attracted
great and still growing attention, because water is an inex-
pensive, readily available, nonflammable, and renewable
source that is safe to industrial processes and to the envi-
ronment.[1] In sharp contrast, most of the organic solvents
used today are associated with high cost, flammability, tox-
icity, carcinogenesis, and so on. Worse still, the use of or-
ganic solvents brings about 80% of chemical waste.[2] None-
theless, water is still not commonly applied as the sole sol-
vent for organic transformations in the laboratory and in
industry.[3] The nucleophilic substitution reaction, a crucial
and frequently used transformation for the formation of C–
C and C–heteroatom bonds in organic synthesis, is seldom
carried out in neat water owing to the limited water solubil-
ity of organic substrates.[3] Although conventional phase-
transfer catalysts enable these reactions to proceed in
water–organic biphasic systems,[4] they still do not preclude
the use of organic solvents, especially halogenated hydro-
carbons, which are regarded as one of the origins for envi-
ronmental disasters and climate warming.
Our group has been involved in the past years in the
development of green catalysts and environmentally
friendly procedures to organic transformations used in the
laboratory and in industry. Very recently, we designed and
synthesized a series of silica-supported multilayer ionic li-
[a] School of Chemistry and Material Science,
Shaanxi Normal University,
XiЈan 710062, P. R. China
Fax: +86-29-85307774
E-mail: weijf@snnu.edu.cn
[b] State Key Laboratory of Applied Organic Chemistry,
Lanzhou University,
Lanzhou 730000, P. R. China
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201001227.
Figure 1. Chart of the brush catalyst and its role in the reaction.
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 229
Eur. J. Org. Chem. 2011, 229–233

J.-f. Wei et al.
SHORT COMMUNICATION
in near-quantitative yields. The dilayer brush with n-octyl
as the terminal group was found to be a more active catalyst
than its mono- and trilayer analogues.
Results and Discussion
Initially, we employed the nucleophilic substitution of
benzyl chloride with NaN3 as a prototypical reaction to
determine suitable reaction conditions and to examine the
activity of the catalyst in neat water. All of the reactions
were carried out by simply stirring a mixture of the catalyst,
benzyl chloride, and NaN3 in neat water; no any organic
cosolvent or other adductive was needed. The results are
listed in Table 1.
Organic azides and thiocyanides are important chemi-
cals[7,8] as pharmaceuticals,[9] energy-rich materials,[10] pesti-
cides,[11] and flexible intermediates as precursors for organic
synthesis.[12] Usually, they are synthesized by the nucleo-
philic substitution reaction of alkyl halides with inorganic
azides or thiocyanides under phase-transfer catalysis condi-
tions. Apart from the need of an organic solvent, these
methods suffer from difficulties in the recovery and recycl-
ing of the catalyst and sometimes low efficiency. Some
attempts have been made to solve this problem.[13] The
group of Varma studied on-water reactions by using surfac-
tant-pillared clays or ultrasound as a catalyst in water or in
a water–petroleum ether system.[13a–13c] Recently, they dis-
closed a microwave-assisted synthesis of these compounds
in water with 47–95% yield.[13d] In consideration of the
wide usage of organic azides and thiocyanides in nucleo-
philic substitutions, and the drawbacks of the traditional
methods for their syntheses, we chose the nucleophilic sub-
stitutions of benzyl and alkyl halides and tosylates with
NaN3 or NaSCN as the nucleophile, respectively, in neat
water medium by using the dilayer brush bearing n-octyl
group as the catalyst. Herein, we wish to describe our pre-
liminary results of the brush in on-water nucleophilic sub-
stitutions under mild conditions.
Table 1. The brush-catalyzed on-water nucleophilic substitution of
benzylic chloride with NaN3 under various conditions.[a]
Entry Catalyst
NaN3
T
t
[h]
Solvent
Yield
[%][c]
[equiv.][b] [equiv.] [°C]
1
2
3
4
5
6
7
8
9
10
11
12
13
14[d]
15[e]
NO
NO
0.02
0.01
0.005
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.1
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
1.1
1.2
1.5
1.3
2.0
80
80
80
80
80
50
60
70
90
100
80
80
80
100
75
5.0
10.0
5.0
8.5
11.0
11.0
8.0
6.5
5.0
4.5
5.0
5.0
5.0
6.0
1.5
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
O/W
H2O
(54.1)
(89.8)
95.4 (99.3)
94.8 (98.7)
89.6 (92.1)
90.1 (94.5)
90.9 (94.9)
92.3 (95.8)
93.6 (94.7)
90.5 (92.3)
87.9 (89.1)
91.5 (93.4)
92.0 (95.2)
84[13b]
The brush catalyst was prepared through a three-step
route according to the procedure we previously report-
ed[6a,6b] with a slight modification (Scheme 1). BET analysis
showed the brush has a SBET of 387 m2/g. Elemental analy-
sis reveals that there are 1.50 mmol/g of imidazolium ions
0.5
69[14]
loaded on the dilayer ionic liquid brush, nearly two times [a] Conditions: benzyl chloride (0.633 g, 5 mmol), H2O (2 mL).
[b] Based on the imidazolium ions. [c] Isolated yield. GC yield is
the amount of imidazolium ions on its monolayer analogue.
given in parentheses. [d] Me4NBr pillared clay as catalyst in petro-
The brush is stable to air and moisture.
leum ether/water reported in ref.[13b] [e] The ionic liquid
[bmim][PF6] as catalyst reported in ref.[14]
As can be seen, the present brush catalyst is efficient for
the nucleophilic substitution of benzyl chloride with sodium
azide in water alone. A loading of 2.0 mol-% (2 mmol imid-
azolium loaded on the brush catalyst/100 mmol substrate)
of the brush catalyst (Table 1, Entry 1) showed marvelous
efficiency to the reaction, affording the desired product in
quantitative yield (GC), in contrast to the reported yields
of 69 and 84% for the same reaction catalyzed by 0.5 equiv.
(50 mol-%) of ionic liquid [bmim][PF6][14] in CH2Cl2/water
(Table 1, Entry 15) or by 0.1 equiv. (10 mol-%) of Me4NBr
pillared clay in petroleum ether/water biphasic system
(Table 1, Entry 14).[13b] Even a loading of 0.5 mol-% of the
brush is sufficient for a smooth reaction to give the desired
product in a yield (89.6%) higher than those mentioned
above.
Examination of the reaction conditions showed that the
most suitable reaction temperature is 80 °C, which is much
lower than that given in a previous report in which Me4NBr
Scheme 1. Synthetic route to the brush catalyst.
230
pillared clay was used as the catalyst.[13b] Furthermore, the
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 229–233

Ionic Liquid Brush as a Highly Efficient and Reusable Catalyst
best results were achieved when 2.0 equiv. of NaN3 were kanes as the substrates, the reaction also proceeded
used with 0.02 equiv. of the catalyst at 80 °C (Table 1, En- smoothly and afforded the desired azides in excellent yields
try 2).
but required a prolonged time under identical conditions
The scope and generality of the present protocol were (Table 2, Entry 1 vs. 2 and Entry 7 vs. 8). With long-chain
investigated by using a series of benzyl and alkyl halides alkyl halides as the substrates, the reaction carried on com-
and tosylates as substrates, NaN3 or NaSCN as nucleo- paratively slower but gave high yields. Cyclohexyl bromide,
phile, and water as the sole solvent. All reactions were car- a secondary alkyl halide, offered the desired product in
ried out under the optimized reaction conditions, except for good yield (88.3%).
the reactions using NaSCN as nucleophile, which was car-
NaSCN, a more powerful nucleophile, underwent the re-
ried out at Յ60 °C. The results are summarized in Table 2. actions quite readily with a brush catalyst loading of
2.0 mol-% and generated the corresponding organic thiocy-
anides in excellent to quantitative yields (Table 2, En-
tries 16–25). Most remarkably, with tosylates as the sub-
Table 2. The brush-catalyzed on-water nucleophilic substitution of
alkyl halides and sulfonates with NaN3 and NaSCN.[a]
strates, the reaction proceeded much faster with a compara-
tively shorter time of completion and provided the products
in nearly quantitative yield. It is worthy to note that iso-
thiocyanide isomers, which are common byproducts in the
substitution of haloalkanes with amphiphilic SCN–, were
not detected by GC analysis in our ionic liquid brush cata-
lyzed reactions of both alkyl halides and tosylates.
Table 3 presents examples that further demonstrate the
scope of the brush-catalyzed on-water reactions. The results
show that all of the reactions of halogenated ketones and
esters with NaN3 or NaSCN were carried out successfully
and cleanly in neat water. Noticeably, some reactions can
be carried out at room temperature (Table 3, Entries 1 and
4) with high yields. The yields are excellent from the view-
point of the industrial importance of these compounds.[7,12]
Entry
R–L
NaNu
t
[h]
T
[°C]
Yield
[%][b]
1
2
3
C6H5CH2Cl
C6H5CH2Br
4-BrC6H5CH2Br
4-NO2C6H5CH2Br
1,4-C6H4(CH2Cl)2
n-C4H9Br
NaN3
NaN3
NaN3
NaN3
NaN3
NaN3
NaN3
NaN3
NaN3
5.0
4.5
4.0
4.5
5.5
6.5
7.0
8.5
12.0
8.5
13.5
4.0
7.0
7.5
0.83
0.5
0.25
1.0
1.0
1.0
1.5
4.5
9.0
0.33
0.67
1.0
80
80
80
80
80
80
80
80
80
80
80
80
80
80
60
60
60
60
60
60
60
60
60
60
60
60
95.4 (99.3)
96.8 (100)
96.2 (99.6)
97.4
4
5[c]
6
94.8 (98.7)
93.1 (100)
95.2 (99.8)
95.9 (100)
95.3 (99.1)
94.0 (98.0)
88.3 (91.0)
97.6 (100)
95.9 (100)
92.8 (100)
95.5 (100)
96.2 (100)
97.5 (100)
97.3
96.0 (99.2)
93.9 (99.9)
91.5 (100)
93.0 (99.4)
92.4 (100)
97.9 (100)
96.3 (100)
94.7 (100)
7
n-C5H11Br
n-C8H17Br
n-C8H17Cl
8[d]
9
10[c]
11
12
13
14
15
16[e]
17
18
19
20[f]
21
22
23
24
25
26
BrCH2(CH2)2CH2Br NaN3
cyclo-C6H11Br
C6H5CH2OTs
n-C4H9OTs
n-C5H11OTs
C6H5CH2Cl
C6H5CH2Br
4-BrC6H5CH2Br
4-NO2C6H5CH2Br NaSCN
1,4-C6H4(CH2Cl)2
n-C4H9Br
n-C5H11Br
n-C8H17Br
n-C8H17Cl
C6H5CH2OTs
n-C4H9OTs
n-C5H11OTs
NaN3
NaN3
NaN3
NaN3
Table 3. The brush-catalyzed on-water nucleophilic substitution of
bromo ketones or bromo esters with NaN3 or NaSCN.[a]
NaSCN
NaSCN
NaSCN
Entry
R–L
NaNu
t
[h]
T
[°C]
Yield
[%][b]
NaSCN
NaSCN
NaSCN
NaSCN
NaSCN
NaSCN
NaSCN
NaSCN
1
2
3
4
5
6
7
8
C6H5COCH2Br
CH3CHBrCO2Et NaN3
Br(CH2)3CO2Et NaN3
NaN3
3.0
5.0
5.0
5.0
4.0
5.0
4.5
5.0
r.t.
80
80
r.t.
r.t.
60
60
r.t.
92
90
93
95
96
82
98
98
BrCH2CO2Et
NaN3
C6H5COCH2Br NaSCN
CH3CHBrCO2Et NaSCN
Br(CH2)3CO2Et NaSCN
BrCH2CO2Et
NaSCN
[a] Conditions: catalyst (0.02 equiv., based on imidazolium ions),
substrate (1.0 equiv.), NaN3 (2.0 equiv.) or NaSCN (1.5 equiv.).
[b] Isolated yield determined by column chromatography. GC yield
is given in parenthesis. [c] 4.0 equiv. of NaN3 were used. [d] Re-
ported yield of 27% using [bmim][PF6] (0.5 equiv.)[14] as catalyst,
75 °C, 3 h. [e] Reported yield of 95.0% (GC) using [P]-
CH2NHP(O)(NMe2)2 (0.01 mol)[13e] as catalyst, 110 °C, 1 h.
[f] 3.0 equiv. of NaSCN were used.
[a] Condition: 0.02 equiv. of imidazolium ions of the brush, sub-
strate (1.0 equiv.), NaN3 (2.0 equiv.) or NaSCN (1.5 equiv.). [b] Iso-
lated yield determined by column chromatography. GC yield is
given in parenthesis.
It is noteworthy that all of the substrates we used in the
reaction are not soluble in water. The complete reaction
and excellent yields of the desired products reflects that they
As shown in Table 2, the brush catalyzes the reaction could efficiently be transferred into the brush without the
successfully with a large scope of substrates, including aid of an organic cosolvent. Thus, the substrates are able
benzyl and alkyl bromides, chlorides, and tosylates. The iso- to be “dissolved” into the immobilized ionic liquid brush,
lated yields range from 88–98% without any detectable by- wherein the anion reagents waited. Accordingly, we suggest
products. More delightfully, in most cases the GC yields of that the reaction occurs inside the brush.
the reactions are quantitative. As expected, benzyl halides
The present heterogeneous catalysts have an advantage
underwent the reaction more rapidly and gave higher yields that at the end of reaction the catalyst can be removed from
than haloalkanes did; the bromides are more reactive than the reaction stream by simple filtration. To investigate the
their chloride analogues. Benzyl bromides possessing elec- recyclability of the brush, we carried out the reaction of
tron-withdrawing substituents undergo the reaction as well benzyl chloride with NaN3 repeatedly under the optimized
as their parent (Table 2, Entries 4 and 18). With chloroal- conditions (Table 4). Ten consecutive preparations of
Eur. J. Org. Chem. 2011, 229–233
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
231

J.-f. Wei et al.
SHORT COMMUNICATION
dry toluene (15 mL), and the mixture was heated at reflux for 24 h.
The solid was then filtered and washed thoroughly with toluene
followed by methanol in a Soxhlet extractor. After drying in vacuo,
benzyl azide showed no observable decrease in the yields
(93.4–95.5%). In each case, the brush catalyst was recovered
by simple filtration, and the experiment was repeated.
a solid (5.1 g) was obtained. SBET = 231 m2/g. IR (KBr disk): ν =
˜
Table 4. Yields of azidomethyl benzene in recycled brush.[a]
3155, 3120, ν(C–H, aromatic); 2947, 2871, ν(C–H, aliphatic); 1555,
1456 ν(C=N) cm–1. Elemental analysis: found C 14.73, H 2.567, N
4.209; revealing that there are 1.50 mmol of imidazolium/g loaded
on the brush. The resulting silica bonding 1,4-bis(imidazole-1-yl)-
butane (5 g, 7.50 mmol of imidazolium) was suspended in a solu-
tion of 1-chlorooctane (5 g, 34 mmol) in dry toluene (20 mL), and
the mixture was heated at reflux for 24 h under a N2 atmosphere.
After the reaction mixture was cooled to room temperature, the
solid was filtered and washed with toluene followed by ethanol in
a Soxhlet extractor. After drying in vacuo, a solid (5.4 g) was ob-
Cycle
1
2
3
4
5
6
7
8
9
10
Yield [%][b] 99.8 99.1 99.4 99.0 99.2 99.7 98.8 99.1 99.5 98. 9
[a] All cycles were carried out by using BnCl (2.53 g, 20 mmol),
NaN3 (2.60 g, 40 mmol), H2O (8.0 mL), ionic liquid brush (0.32 g,
0.08 mmol), 5 h, 80 °C. [b] GC yield.
Elemental analysis revealed that after the 10th cycle the
brush catalyst had nearly the same content of nitrogen as
that on the brush. Infrared spectral analysis showed that
the main absorption peaks remained unchanged as com-
pared to those of the fresh catalyst. These results indicate
that the brush catalyst is stable in the reaction. The high
recyclability of this catalytic system allows for a more econ-
omic and environmentally friendly process.
We did not purposely study the mechanism of the reac-
tion; however, the observations that the substrates bearing
a better leaving group, more powerful nucleophiles, and, es-
pecially, that the α-haloketones and α-halo esters are more
reactive to the reaction may provide a clear evidence of the
SN2 reaction for the present protocol.
Compared with the standard procedures, our method of-
fers a series of important advantages such as (i) on-neat
water reaction conditions, (ii) excellent yields, (iii) easier
workup, and (iv) recoverable and reusable catalyst. This is
very significant to industrial applications for this brush cat-
alyst.
tained. SBET = 181 m2/g. IR (KBr disk): ν = 3151, 3084 ν(C–H,
˜
aromatic); 2936, 2855 ν(C–H, aliphatic); 1568, 1458 ν(C=N) cm–1.
Elemental analysis: found C 14.11, H 2.341, N 3.540; revealing that
the brush contains 1.27 mmol of imidazolium/g.
Typical Procedure for the Synthesis of Organic Azides as Exem-
plified by Benzyl Azide: Benzyl chloride (0.633 g, 5.0 mmol), so-
dium azide (0.65 g, 10 mmol), the brush catalyst (0.0787 g,
0.1 mmol imidazolium), and distilled water (2.0 mL) were admixed
in a 25-mL round-bottomed flask, and the mixture was stirred at
80 °C in an oil bath until the substrate could not be detected by
TLC. The reaction mixture was then cooled to room temperature
and ethyl acetate (10 mL) was added to extract the alkyl azide. The
catalyst was separated by filtration and washed with ethyl acetate
and water. The organic layer of the filtrate was separated, and the
aqueous layer was extracted with ethyl acetate (3ϫ5 mL). The
combined extracts was washed with saturated brine and dried with
anhydrous sodium sulfate. The solvent was removed under reduced
pressure to give the crude product, which was purified by silica gel
column chromatography (petroleum ether/ethyl acetate, 9:1) to give
benzyl azide (0.635 g, 95.4%) as a colorless oil. 1H NMR
(300 MHz, CDCl3): δ = 7.18–7.26 (m, 5 H), 4.19 (s, 2 H) ppm.
Typical Procedure for the Synthesis of Organic Thiocyanides as Ex-
emplified by Benzyl Thiocyanate: Benzyl bromide (0.855 g,
5.0 mmol), sodium thiocyanate (0.6075 g, 7.5 mmol), the brush
(0.0787 g, 0.1 mmol), and distilled water (2.0 mL) were admixed in
a 25-mL round-bottomed flask, and the mixture was stirred at
60 °C. Similar workup gave benzyl thiocyanate (0.718 g, 96.2%) as
Conclusions
In conclusion, we have demonstrated a “real” on-water
protocol for nucleophilic substitution reactions that com-
pletely avoids the use of any organic cosolvent or other ad-
ductive. The reaction is general and gives the desired prod-
ucts in excellent to quantitative yields. The high efficiency,
simplicity of product isolation, outstanding recyclability,
and organic solvent free and water alone conditions makes
the catalyst and the process available in academic laborato-
ries and could find industrial applications in the future.
Further studies on the application of this unique catalyst to
other reactions are in progress in our laboratory.
1
an oil. H NMR (300 MHz, CDCl3): δ = 7.27 (m, 5 H), 4.03 (s, 2
H) ppm.
Recycling of the Brush Catalyst: The reaction of benzyl chloride
and NaN3 was selected as the model reaction and was performed as
described above, except that the separated catalyst was successively
reused for the next reaction. For the next cycle, benzyl chloride and
a solution of sodium azide in water were added successively, and
the previous procedure was repeated. After 10 cycles, the quality
of the ionic liquid brush was 0.11 g; spectroscopic data (IR) were
identical to that of the initial ionic liquid brush sample.
Supporting Information (see footnote on the first page of this arti-
cle): Spectroscopic data and copies of the H NMR spectra for all
Experimental Section
1
General Procedure for the Synthesis of the Ionic Liquid Brush: 1,4-
Bis(imidazole-1-yl)butane was synthesized according to the litera-
ture.[15] M.p. 61–63 °C. 1H NMR (300 MHz, [D6]DMSO): δ = 1.61
(m, 4 H), 3.96 (m, 4 H), 6.89 (s, 2 H), 7.14 (s, 2 H), 7.62 (s, 2
H) ppm. 13C NMR (300 MHz, [D6]DMSO): δ = 28.1, 39.4, 39.6,
39.9, 40.2, 40.5, 45.7, 119.7, 128.9, 137.7 ppm. Silica modified with
triethyl 3-chloropropanylsilicate was prepared according to the lit-
products.
Acknowledgments
The authors are grateful to the National Foundation of Natural
Science in China (Grant No. 21072123 and 20906059).
erature.[16] SBET = 385 m2/g. IR (KBr disk): ν = 2958, 2930, 2871
˜
ν(C–H, aliphatic) cm–1. 1,4-Bis(imidazole-1-yl)butane (4.3 g,
[1] a) P. T. Anastas, J. C. Warner, Green Chemistry: Theory and
Practice, Oxford University Press, New York, 1998; b) M.
22.5 mmol) was added to a suspension of modified silica (4.5 g) in
232
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 229–233

Ionic Liquid Brush as a Highly Efficient and Reusable Catalyst
Eissen, J. O. Metzger, E. Schmidt, U. Schneidewind, Angew.
Chem. Int. Ed. 2002, 41, 414–436; c) I. T. Horváth, Acc. Chem.
Res. 2002, 35, 685; d) S. Narayan, J. Muldoon, M. G. Finn,
V. V. Fokin, H. C. Kolb, K. B. Sharpless, Angew. Chem. Int. Ed.
2005, 44, 3275–3279.
[9]
a) T. S. Lin, W. H. Prusoff, J. Med. Chem. 1978, 21, 109–112;
b) G. T. Le, G. Abbenante, P. K. Madala, H. N. Hoang, D. P.
Fairlie, J. Am. Chem. Soc. 2006, 128, 12396–12397.
[10]
a) D. E. Chavez, M. A. Hiskey, J. Energ. Mater. 1999, 17, 357–
377; b) E. A. Zhurova, V. G. Tsirelson, A. I. Stash, M. V.
Yakovlev, A. A. Pinkerton, J. Phys. Chem. B 2004, 108, 20173–
20179; c) M. H. V. Huynh, M. A. Hiskey, E. L. Hartline, D. P.
Montoya, R. Gilardi, Angew. Chem. Int. Ed. 2004, 43, 4924–
4928; d) A. N. Ali, S. F. Son, M. Hiskey, J. Propul. Power 2004,
20, 120–135; e) D. M. Badgujar, M. B. Talawar, S. N. Asthana,
P. P. Mahulikar, J. Hazard. Mater. 2008, 151, 289–305.
a) C. Song, M. E. Scharf, Pest. Manag. Sci. 2009, 65, 697–703;
b) S. M. Ali, D. Clarke, G. R. Cliff, G. A. J. Morrison, Chem.
Res. (S) 1981, 234; c) S. A. Shiba, Arch. Pharm. Pharm. Med.
Chem. 1998, 331, 91–96.
a) K. Ogura in Comprehensive Organic Synthesis (Eds.: B. M.
Trost, I. Fleming), Pergamon Press, Oxford, 1991, vol. 1. p.
505; b) H. C. Kolb, K. B. Sharpless, Drug Discovery Today
2003, 8, 1128; c) P. D. Magnus, Tetrahedron 1977, 33, 2019; d)
F. D. Anna, S. Marullo, R. Noto, J. Org. Chem. 2008, 73, 6224–
6228.
[2] a) K. H. Shaughnessy, R. B. DeVasher, Curr. Org. Chem. 2005,
9, 585–604; b) U. M. Lindstrom, Chem. Rev. 2002, 102, 2751–
2772.
[3] a) C. J. Li, Chem. Rev. 1993, 93, 2023–2035; b) C. J. Li, T. H.
Chang, Organic Reactions in Aqueous Media, John Wiley &
Sons, New York, 1997; c) P. A. Grieco, (Eds.) Organic Synthesis
in Water, Blackie Academic and Professional, London, 1998;
d) A. Lubineau, J. Auge, Top. Curr. Chem. 1999, 206, 1; e) C. J.
Li, Chem. Rev. 2005, 105, 3095–3165; f) C. Arani, V. F. Valery,
Chem. Rev. 2009, 109, 725–748.
[11]
[12]
[4] E. V. Dehmlow, S. S. Dehmlow Phase Transfer Catalysis, 3rd
ed., VCH, Weinheim, 1993.
[5] a) C. Betti, D. Landini, A. Maia, Tetrahedron 2008, 64, 1689–
1695; b) D. Landinia, A. Maia, Tetrahedron Lett. 2005, 46,
3961–3963; c) X. J. Cui, S. G. Zhang, F. Shi, Q. H. Zhang, X. Y.
Ma, L. J. Lu, Y. Q. Deng, ChemSusChem 2010, 3, 1043–1047.
[6] a) J. F. Wei, Y. Y. Bi, Y. M. Wang, X. Y. Shi, CN101045213,
2007; b) J. F. Wei, Y. M. Wang, Y. Y. Bi, X. Y. Shi,
CN101049575, 2007; c) J. F. Wei, J. Jiao, J. J. Feng, J. Lv, X. R.
Zhang, X. Y. Shi, Z. G. Chen, J. Org. Chem. 2009, 74, 6283–
6286.
[7] a) E. F. V. Scriven, K. Turnbull, Chem. Rev. 1988, 88, 297–368;
b) S. Bräse, C. Gil, K. Knepper, V. Zimmermann, Angew.
Chem. Int. Ed. 2005, 44, 5188–5240; c) A. W. Erian, S. M. She-
rif, Tetrahedron 1999, 55, 7957–8024.
[8] a) D. E. Shalev, S. M. Chiacchiera, A. E. Radkowsky, E. M.
Kosower, J. Org. Chem. 1996, 61, 1689–1701; b) T. Patonay,
R. V. Hoffman, J. Org. Chem. 1994, 59, 2902–2905; c) H. Take-
uchi, S. Yanagida, T. Ozaki, S. Hagiwara, S. Eguchi, J. Org.
Chem. 1989, 54, 431–434; d) N. Buckley, N. J. Oppenheimer, J.
Org. Chem. 1996, 61, 7360–7372.
[13] a) R. S. Varma, D. Kumar, Catal. Lett. 1998, 53, 225–227; b)
R. S. Varma, K. P. Naicker, Tetrahedron Lett. 1998, 39, 2915–
2918; c) R. S. Varma, K. P. Naicker, D. Kumar, J. Mol. Catal.
A: Chem. 1999, 149, 153–160; d) Y. Ju, D. Kumar, R. S. Varma,
J. Org. Chem. 2006, 71, 6697–6700; e) M. S. Chiles, D. D. Jack-
son, P. C. Reeves, J. Org. Chem. 1980, 45, 2915–2918.
[14] N. M. T. Lourenço, C. A. M. Afonso, Tetrahedron 2003, 59,
789–794.
[15] Y. H. So, Macromolecules 1992, 25, 516–520.
[16] T. Kovalchuk, H. Sfihi, L. Kostenko, V. Zaitsev, J. Fraissard,
J. Colloid Interface Sci. 2006, 302, 214–229.
Received: August 31, 2010
Published Online: November 24, 2010
Eur. J. Org. Chem. 2011, 229–233
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
233