Star-shaped heavily fluorinated aromatic sulfurs: Stabilization of palladium nanoparticles active as catalysts in cross-coupling reactions

Article abstract of DOI:10.1039/b707776a

Two star-shaped heavily fluorinated compounds have been prepared and used as stabilizers of palladium nanoparticles. These materials are useful and reutilizable catalysts in Mizoroki-Heck, Suzuki and Sonogashira cross-couplings. The Royal Society of Chemi

Full text of DOI:10.1039/b707776a

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PAPER
www.rsc.org/njc | New Journal of Chemistry
Star-shaped heavily fluorinated aromatic sulfurs: stabilization of
palladium nanoparticles active as catalysts in cross-coupling reactionsw
Sandra Niembro, Adelina Vallribera* and Marcial Moreno-Man
˜
asz
Received (in Durham, UK) 29th May 2007, Accepted 8th August 2007
First published as an Advance Article on the web 5th September 2007
DOI: 10.1039/b707776a
Two star-shaped heavily fluorinated compounds have been prepared and used as stabilizers of
palladium nanoparticles. These materials are useful and reutilizable catalysts in Mizoroki–Heck,
Suzuki and Sonogashira cross-couplings.
Introduction
(iii) possessing an endowed functional group with high affinity
for metals.
Fluoroorganic compounds have a unique set of physical and
1
chemical properties. The special physical properties are gov-
In recent years, nanoparticles suspensions of transition
5
metals have shown efficient activities in the field of catalysis.
erned by the extremely low polarizability of fluorine, and the
combination of high electronegativity with a moderate size.
Another characteristic of fluoroorganic compounds is the
excellent match between the fluorine and carbon 2s and 2p
orbitals which explains the extreme chemical stability of the
carbon–fluorine bond. The unique properties of highly fluori-
nated and perfluorinated solvents and reagents have opened
up several solutions to the problem of recovering and recycling
catalysts (fluorous biphase catalysis) and to a sustainable
green chemistry (non-toxicity and extreme chemical
One of the key goals in the use of metal nanoparticles in
catalysis is the recyclability of the metal colloids. We present
here the synthesis of new aromatic sulfurs from commercially
accessible compounds such as cyanuric chloride and hexa-
fluoro- or hexachlorobenzene. Two methods are proposed
using stoichiometric amounts of thiols. Two heavily fluori-
nated star-shaped aromatic compounds, possessing functional
groups with an affinity for palladium, have been prepared
(
Fig. 1, 4c (63.9% F) and 7c (65.8% F)) and used in the
preparation of palladium(0) nanoparticles. These materials are
useful and reutilizable catalysts in Mizoroki–Heck, Suzuki and
Sonogashira cross-couplings.
2
inertness).
Metallic nanoparticles, in general defined as having a dia-
meter between 1 and 100 nm, have attracted a great deal of
3
attention in the last ten years. They are formed following a
process of several steps which consist first in the generation of
atoms, then nucleation to form a cluster and finally growing of
the cluster up to a certain volume. Of course the cluster must
be surrounded by a shell of an adequate protecting agent that
prevents their agglomeration. Some of the well known protect-
ing agents provide steric stabilization through a functional
group with high affinity for metals including thiols, amines,
phosphines and sulfides. Heavily fluorinated compounds do
not seem ideal stabilizers for nanoparticles. It is well known
that a consequence of the low polarizability of perfluoro-
carbons is very weak intermolecular dispersion interactions
and an extremely low surface tension as there are very small
attractive interactions among themselves and other materials.
Despite these properties some of us have previously reported
that some heavily fluorinated compounds can indeed stabilize
Results and discussion
We have based the synthesis of 2,4,6-tri-substituted-1,3,5-
triazines, 4, on the functionalization of the less expensive
cyanuric chloride, 1. Several specific protocols have been
developed for the nucleophilic substitution of the C–Cl bond
6
by C–O, C–N and C–S. We report here that chloride can be
exchanged in compound 1 with a variety of sulfur nucleophiles
by treating thiols 2a–c in THF in the presence of Cs
2 3
CO as a
base and substoichiometric amounts of Bu NCl to solubilize
4
the thiolate anion (Scheme 1 and entries 1, 2, 3 of Table 1).
7
This method was previously described by our group to
N
perform S Ar reactions of weakly activated 4-fluorophenyl-
4
transition-metal nanoparticles. As an extension we wanted to
design new constituents of protecting shields for nanoparticles
possessing different features that could enhance the stabilizing
effects: (i) heavily perfluorinated; (ii) sterically demanding; and
Department of Chemistry, Universitat Auto´noma de Barcelona,
Cerdanyola, 08193 Barcelona, Spain. E-mail:
adelina.vallribera@uab.cat; Fax: 34 93 581 1265; Tel: 34 935813045
w Dedicated to Professor Vicente Gotor on the occasion of his 60th
birthday.
z Deceased 20th February 2006.
Fig. 1 Star-shaped heavily fluorinated compounds.
9
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substituted products, only di- (5a, b, Scheme 1 and entries 4
and 5 of Table 1) and tetra-substituted (6a, d, Scheme 1 and
entries 6 and 7 of Table 1) compounds could be prepared
depending on the stoichiometric amount of nucleophile. The
monosubstituted product appeared to react with the nucleo-
phile at least as readily as the hexafluorobenzene. The action
of nucleophilic thiolate agents on monosubstituted derivatives
6 5
(C F SR) led to the formation of para-isomers. The known
ability of sulfur to stabilize a negative charge next to it, due to
favourable overlap interactions with available d orbitals,
rationalises the observed para-directing orientation of the
8
compounds. Further sub-
–
SR group giving para-C
6
F
4
(SR)
2
stitutions are governed by significant activation of –SR at para
and –F at ortho positions and led to C F (SR) with the two
6
2
4
9
remaining fluorines para to each other (Scheme 1).
Then, conditions were changed to force reactivity. Reaction
of hexafluorobenzene, 2, with 2d at 130 1C using NaH in
1
0
refluxing tetraglyme gave the tetrasubstituted compound 6d.
However, the reaction of hexachlorobenzene, 3, with sodium
thiolates of 2a, d, c gave the hexasubstituted products in 93,
7
3, 54% yields, respectively (Scheme 1 and entries 8, 9 and 10
of Table 1). Heavily fluorinated 7c (65.7% of F) was obtained
in 54% yield.
As we have mentioned, we prepared 4c and 7c as candidates
for nanoparticle stabilization. Thus, palladium nanoparticles
were prepared by the reduction of soluble ionic Na (Pd Cl )
2
2
6
Scheme 1 Preparation of aromatic sulfurs 5, 6 and 7.
(
prepared from palladium(II) chloride and sodium chloride,
see experimental part) with methanol at 60 1C in the presence
of compounds 4c and 7c. Addition of sodium acetate induced
precipitation of the material. The results are summarized in
Table 2. As expected when working with an excess of palla-
dium salt (ratio 2), nanoparticles possessing a higher amount
of metal (13.3%) were obtained. In all cases very small
nanoparticles of fcc-Pd(0) were formed (1.7–5 nm, Table 2
and Fig. 2). The nanoparticle size is normally associated with
its reactivity. The decomposition points of the materials were
similar to the melting points of 4c and 7c. With respect to the
phenomenon of stabilization we propose that nanoparticles
are entrapped in the solid network of the heavily fluorinated
compounds. Initial interactions are probably due to the pre-
sence of sulfur and nitrogen, good coordinating atoms for
palladium. Then, the presence of long perfluorinated chains
giving a special shape to the molecules induces the steric
stabilization that prevents agglomeration of the nanoparticles.
These materials were tested as catalysts in cross-coupling
reactions (Scheme 2). We have described fluorous biphasic
sulfonamides and worked with only one mol of nucleophile
per chloride or fluoride atom, an important requirement when
using valuable nucleophiles. Heavily fluorinated 4c (63.9% of
F) was obtained in 68% yield (entry 3 of Table 1).
Moreover, we explored the nucleophilic aromatic substitu-
tion of hexahalobenzenes 2 and 3. First we selected hexafluoro-
benzene having in mind that among halogens fluoro is gen-
erally the best leaving group in S Ar. Furthermore these
N
substitutions are accelerated by electron-withdrawing effects,
especially in positions ortho and para to the leaving group, and
hindered by electron-donating groups. Using the same experi-
mental protocol described for 1 (see experimental part, in this
case refluxing THF was used), substitution of the six fluorine
atoms of hexafluorobenzene by thiolates was not achieved.
Furthermore there was no evidence of mono-, tri- or penta-
Table 1 Reactions of 1, 2 and 3 with thiolates (Schemes 1 and 2)
systems that permitted recovery and reutilization of palladium
4a,g
a
Entry Substrate RSH Method Time Product Yield(%)
nanoparticles as catalyst.
Now we intend to take advantage
of the low solubility of the highly fluorinated palladium
nanoparticles in organic solvents and water to use them as
heterogeneous catalysts.
1
2
3
4
5
6
7
8
9
1
a
1
1
1
2
2
2
2
3
3
3
2a
2b
2c
2a
2b
2a
2d
2a
2d
2c
a
a
a
a
a
a
a
b
b
b
4 d
6 d
7 d
1 d
3 d
3 d
14 d
42 h
42 h
42 h
4a
4b
4c
5a
5b
6a
6d
7a
7d
7c
68
85
68
81
94
88
92
93
73
54
11
For the Mizoroki–Heck reaction we used tributylamine as
base in refluxing acetonitrile and catalytic material corre-
n
sponding to Pd (1). The weight of the catalyst introduced in
the reaction corresponded to 4% molar palladium with respect
to the limiting reagent. The material was reused after centri-
fugation and we carried out the reaction five consecutive times
with the same batch of catalyst without loss of activity
10
0
Method a: RSH, Cs
2 3 4
CO (excess), NBu Cl (12 mol%), THF, r.t.;
Method b: RSH, NaH, tetraglyme, 130 1C.
(
Table 3).
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Table 2 Palladium nanoparticles stabilized by fluorous compounds 4c and 7c
Initial molar
ratio Pd : 4
No. of atoms
per particle
Electron
diffraction
Decomposition
point (1C)
a
b
c
d
Material
Stabilizer
f (nm)
% Pd
2
Pd
Pd
Pd
Pd
n
n
n
n
(1)
(2)
(3)
(4)
4c
4c
4c
7c
2.03
2.04
1.06
0.98
2.7 ꢂ 0.8
2.2 ꢂ 0.8
1.7 ꢂ 0.3
5 ꢂ 2
6.9 ꢃ 10
fcc Pd
fcc Pd
fcc Pd
fcc Pd
11.87
13.30
7.30
113–115
112–114
113–116
142–144
2
3.8 ꢃ 10
2
1.7 ꢃ 10
3
4.4 ꢃ 10
3.68
a
b
c
In the form of PdCl
2
.
Determined by transmission electron microscopy analysis (HRTEM). From 0.74Vnanoparticle/Vatom; 0.74 is the
d
occupation factor for a face-centred cube crystal structure. Pd% determined by inductively coupled plasma (ICP).
For the reaction between 4-bromoacetophenone and phenyl
Conclusions
1
boronic acid (Suzuki cross-coupling) we used potassium
2
A series of new aromatic thioethers have been prepared from
commercial sources. Two methodologies can be used that
work with only one mol of nucleophile per chloride or fluoride
atom, an important requirement when using valuable thiols.
We have prepared two heavily fluorinated star-shaped com-
pounds possessing functional groups with high affinity for
metals that were designed to stabilize palladium nanoparticles.
Small palladium nanoparticles could be prepared and these
materials proved to be efficient as recoverable catalysts in
cross-coupling reactions.
carbonate as base in mixtures of DMF–H O at 110 1C and
2
0
.5% molar of Pd (2). We explored the reutilization of the
n
catalyst after centrifugation. The same batch was used five
times without any appreciable loss of activity (Table 3).
n
Nanoparticles Pd (2) containing 13.3% of metal were tested
1
3
also in the Sonogashira coupling of 4-iodoanisole and
phenylacetylene using copper as cocatalyst. We carried out
some preliminary reactions using diisopropylamine as a base.
We soon noticed that palladium nanoparticles were damaged
through the action of the amine, probably due to the nitrogen
atom donor ability. Best results were obtained using an
inorganic base, potassium carbonate, in refluxing ethanol.
For an optimal reutilization of the catalyst the reaction
Experimental
4g
Compounds 10 , 13
14
15
and 16
have been previously
mixture was centrifuged and the residue consisting of Pd
n
(2)
reported.
and K CO was directly reused in the subsequent reaction.
3
2
Normally recovered nanoparticles were washed with water to
extract the inorganic base. However, in Sonogashira condi-
tions addition of water was unsuccessful. To ensure that a
sufficient quantity of base was present in the next reaction
cycle, one equivalent of potassium carbonate was added. The
reaction was carried out six consecutive times with the same
batch of palladium nanoparticles (Table 3).
Typical experiment using cyanuric chloride
A solution of cyanuric chloride, 1, (1.01 g, 5.48 mmol) and
tetrabutylammonium chloride (0.034 g, 0.12 mmol) in 7 mL of
anhydrous THF was added under argon via cannula to a stirred
suspension of caesium thiolate in 8 mL of anhydrous THF,
2 3
made from Cs CO (11.11 g, 34.10 mmol) and propanethiol (1.5
mL, 16.54 mmol). The mixture was stirred at room temperature
during 4 days. Salts were filtered and the solvent evaporated.
The residue was passed through a column of silica gel with a
mixture of hexanes–AcOEt as eluent to afford 2,4,6-tris(pro-
pylthio)-1,3,5-triazine, 4a, (1.13 g, 68%). IR (ATR): 2964, 2927,
ꢁ
869, 1480, 1262, 1233, 631 cm ; H-NMR (CDCl , 250 MHz):
3
1 1
2
d = 1.02 (t, J = 7.4 Hz, 9H), 1.73 (m, 6H), 3.05 (t, J = 7.2 Hz,
1
3
6
H); C-NMR (CDCl
Anal. calcd for C12
1.69; found: C, 47.40; H, 6.92; N, 13.77; S, 31.45%.
3
, 62.5 MHz): 13.7, 22.9, 32.5, 179.8.
21 3 3
H N S : C, 47.49; H, 6.97; N, 13.84; S,
3
Fig. 2 HRTEM images, particle size distribution and electron
Scheme 2 Tested cross-coupling reactions using palladium nano-
particles as catalyst.
diffraction of Pd
n
(3).
9
6 | New J. Chem., 2008, 32, 94–98
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Table 3 Experimental conditions for reactions shown in Scheme 2
a
Reaction
Base
Solvent
CH CN
DMF–H
EtOH
Catalyst Pd (mol%) T (1C) Time (h)
Yields of product (%) for five consecutive cycles
b
reflux 48/48/72/72/72 10 89 (68% isolated)/95/98/93/100
Mizoroki–Heck Bu
Suzuki
Sonogashira
3
N
3
Pd
O 95/5 Pd
Pd
n
(1)
n
(2)
n
(2)
4.1
0.5
1
c
13 98 (91% isolated)/100/100/96/94
K
K
2
CO
CO
3
2
110
80
4/4/4/4/4
2/2/2/2/2/2
c
16 100 (81% isolated)/100/100/100/100/72
2
3
a
b
Reaction times for consecutive runs. Determined by H-NMR. Determined by GC using undecane as internal standard.
1
c
2
,4,6-Tris(hexadecylthio)-1,3,5-triazine, 4b
1,4-Difluoro-2,3,5,6-tetrakis(dodecylthio)benzene, 6d
ꢁ
1
1
Mp 74–75 1C; IR (ATR): 2958, 2917, 2845, 1491, 1458, 1263,
IR (ATR): 2958, 2914, 2846, 1466, 1377 cm
(CDCl , 250 MHz): d = 0.86 (t, J = 6.5 Hz, 12H), 1.23 (m,
64H), 1.36 (m, 8H), 1.53 (m, 8H), 2.93 (t, J = 7.2 Hz, 8H);
; H-NMR
ꢁ1
1
1
249, 1232 cm
;
H-NMR (CDCl
3
, 250 MHz): d = 0.88
t, J = 6.5 Hz, 9H), 1.25 (s, 72H), 1.41 (m, 6H), 1.69 (m, 6H),
3
(
1
.07 (t, J = 7.4 Hz, 6H); C-NMR (CDCl
3
13
3
3
, 62.5 MHz): 14.5,
3
C-NMR (CDCl , 62.5 MHz): 14.4, 23.0, 29.0, 29.5, 29.7,
2
3.0, 29.2, 29.5, 29.7, 29.9, 30.0, 30.1, 30.6, 32.3, 179.9. Anal.
29.8, 29.9, 30.0, 30.1, 32.4, 35.7 (t, J = 3.1 Hz), 127.7 (m),
159.2 (dd, J = 242.2 and 3.8 Hz); Anal. calcd for C H F S :
calcd for C H N S : C, 72.02; H, 11.73; N, 4.94; S, 11.31;
3
5
1
99
3
54 100 2 4
found: C, 72.03; H, 11.63; N, 5.04; S, 10.97%.
C, 70.83; H, 11.01; found: C, 70.71; H, 11.03%.
Typical experiment using hexachlorobenzene
2
,4,6-Tris(1H,1H,2H,2H-perfluorodecylthio)-1,3,5-triazine, 4c
A mixture of NaH 60% suspension in mineral oil (0.23 g, 5.75
mmol) and 1H,1H,2H,2H-perfluorodecylthiol (1.3 mL, 4.49
mmol) in tetraglyme (24 mL) in a Schlenk tube was stirred at
r.t. for one hour. Then, hexachlorobenzene was added (0.70
mmol) and the mixture was stirred at 130 1C for 42 hours. The
The reaction mixture was stirred at room temperature during 7
days. Then, water and ethyl acetate were added and the solid
was filtered, and washed with water and acetone. The solid
was suspended in FC77 (perfluoro compounds, mainly C8)
under stirring at 50 1C during 2 hours and then filtered and
dried.
2 2
formed solid was filtered and washed with CH Cl . Then, the
solid was suspended in FC77 under stirring at 50 1C during 2
hours and then filtered and dried to afford 1.094 g (54%) yield
ꢁ
1
Mp 113–115 1C; IR (ATR): 1470, 1242, 1196, 1142 cm
;
1
H-NMR (CDCl
3
+ FC113 (1,1,2-trichloro-1,2,2-trifluoro-
of hexakis(1H,1H,2H,2H-perfluorodecylthio)benzene 7c. Mp
ꢁ1
ethane), 250 MHz): d = 2.63 (m, 6H), 3.38 (t, J = 7.4 Hz,
1
41–143 1C; IR (ATR): 1241, 1198, 1143, 1082 cm
H-NMR (CDCl3 + FC113 (1,1,2-trichloro-1,2,2-trifluoro-
;
1
H); C-NMR (CDCl
3
6
3
, 62.5 MHz): 22.1, 32.5 (t, J = 22.4
+
1
Hz), 180.2; MALDI-TOF: m/z 1515.96 (M ).
ethane), 250 MHz): d = 2.39 (m, 12H), 3.30 (t, J = 8.0 Hz,
1
3
1
2H); C-NMR (CDCl , 62.5 MHz): 29.7, 32.5 (t, J = 23.1
3
+
1
,2,4,5-Tetrafluoro-3,6-bis(propylthio)benzene, 5a
Hz), 148.2; MALDI-TOF: m/z 2945.86 (M ).
ꢁ
1
Mp 38–40 1C; IR (ATR): 2948, 2929, 2869, 1458, 945 cm
;
Hexakis(propylthio)benzene, 7a
1
H-NMR (CDCl
m, J = 7.3 Hz, 4H), 2.91 (t, J = 7.2 Hz, 4H); C-NMR
CDCl , 62.5 MHz): 13.3, 23.5, 36.9, 114.7 (m), 147.3 (J =
47.9 Hz). Anal. calcd for C12 : C, 48.31; H, 4.73;
found: C, 48.55; H, 4.64%.
3
, 250 MHz): d = 1 (t, J = 7.3 Hz, 6H), 1.60
ꢁ
1 1
IR (ATR): 2959, 2928, 2870, 1457, 1377, 1271, 632 cm ; H-
13
(
(
NMR (CDCl , 250 MHz): d = 0.90 (t, J = 7.3 Hz, 18H), 1.44
3
3
1
3
(
m, J = 7.3 Hz, 12H), 2.91 (t, J = 7.4 Hz, 12H); C-NMR
CDCl , 62.5 MHz): 13.8, 23.0, 39.9, 145.9 (m), 147.2 (J =
47.9 Hz). Anal. calcd for C24 : C, 55,12; H, 8.09; found:
C, 55.22; H, 8.30%.
2
14 4 2
H F S
(
3
2
42 6
H S
1
,2,4,5-Tetrafluoro-3,6-bis(hexadecylthio)benzene, 5b
Mp 76–79 1C; IR (ATR): 2913, 2847, 1463, 953 cm ; H-
NMR (CDCl , 250 MHz): d = 0.87 (t, J = 6.5 Hz, 6H), 1.38
m, 48H), 1.38 (m, 4H), 1.56 (m, 4H), 2.93 (t, J = 7.3 Hz, 4H);
Typical preparation of nanoparticles
ꢁ1 1
A mixture of palladium chloride (0.035 g, 0.20 mmol), sodium
chloride (0.012 g, 0.21 mmol) and 2 mL of methanol was
stirred at room temperature for 24 h. The mixture was filtered
through a glass wool plug. Additional methanol (28 mL) was
added to the filtrate. The solution was heated at 60 1C under
stirring and 2,4,6-tris(1H,1H,2H,2H-perfluorodecylthio)-
3
(
1
3
C-NMR (CDCl
9.8, 29.9, 30.0, 30.2, 32.3, 35.0, 114.8 (m), 147.2 (J = 247.9
Hz). Anal. calcd for C33 : C, 68.83; H, 10.03; found: C,
3
, 62.5 MHz): 14.5, 23.1, 28.7, 29.4, 29.7,
2
66 4 2
H F S
6
8.89; H, 10.28%.
1
,3,5-triazine, 4c, (0.149 g, 0.10 mmol) was added. Then, the
mixture was heated under stirring during 24 h. Sodium acetate
0.094 g) was added and stirring was maintained at room
1
,4-Difluoro-2,3,5,6-tetrakis(propylthio)benzene, 6a
(
ꢁ
1 1
IR (ATR): 2962, 2925, 2868, 1377 cm ; H-NMR (CDCl
3
,
temperature for 1 h. The formed black solid was filtered,
washed with methanol, water and acetone; it was then dried
2
8
1
50 MHz): d = 0.98 (t, J = 7.3 Hz, 12H), 1.55 (m, J = 7.3 Hz,
H), 2.91 (t, J = 7.3 Hz, 8H); C-NMR (CDCl , 62.5 MHz):
13
3
n
to afford 0.283 g of a black solid Pd (2), which had a
1
3.6, 23.4, 37.7 (t, J = 2.9 Hz), 159.4 (dd, J = 241.3 and 3.8
9
decomposition point of 112–114 1C. The IR, H-NMR and
C-NMR of the solid were identical to those of 4c. The size of
1
13
Hz); F-NMR (235.2 MHz, CDCl ): d = ꢁ98; MS: m/z 410
3
+
M ), 368, 326, 284, 242, 208, 177, 43. Anal. calcd for
(
the nanoparticles was 2.2 ꢂ 0.8 nm, as determined by trans-
C H F S : C, 52.64; H, 6.87; found: C, 52.68; H, 7.01%.
8
mission electron microscopy. Pd analysis (ICP): 13.30%.
1
28 2 4
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Mizoroki–Heck reaction. Typical experimental procedure
´
2 (a) I. T. Horvarth, Acc. Chem. Res., 1998, 31, 641; (b) R. H. Fish,
Chem.–Eur. J., 1999, 5, 1677; (c) E. G. Hope and A. M. Stuarts, J.
Fluorine Chem., 1999, 100, 75; (d) E. de Wolf, G. van Koten and
B.-J. Deelman, Chem. Soc. Rev., 1999, 28, 37; (e) M. Cavazzini, F.
Montanari, G. Pozzi and S. Quici, J. Fluorine Chem., 1999, 94, 183;
Butyl acrylate (0.059 mL, 0.41 mmol), iodobenzene (0.030 mL,
0
n
.27 mmol), Pd (1) (0.010 g, 0.011 mmol), tributylamine (0.130
mL, 0.55 mol) and 4 mL of acetonitrile were stirred at 80 1C
during 48 hours. Then the suspension was centrifuged to
afford a black solid and a solution which was decanted and
the solvent evaporated. Then CH Cl was added and the
(
f) J. Rabai, Z. Szlavik and I. T. Horvarth, in Chemistry in fluorous
biphasic systems, in Handbook of Green Chemistry and Technology,
ed. J. Clark and D. Macquarrie, Blackwell Science Ltd, Oxford,
UK, 2002, p. 520; (g) J. A. Gladysz and D. P. Curran, Tetrahedron,
2
2
2
002, 58, 3823; (h) M. Meseguer, M. Moreno-Man
Vallribera, Tetrahedron Lett., 2000, 41, 4093.
For recent reviews see: (a) A. Rocoux, J. Schulz and H. Patin,
Chem. Rev., 2002, 102, 3757; (b) M. Moreno-Manas and R.
˜
as and A.
organic solution was washed with 1 M hydrochloric acid.
The organic layer was dried and the solvent evaporated. The
residue was purified by chromatography through silica-gel
using hexane–ethyl acetate 95/5 as eluent to give 0.0370 g
3
˜
Pleixats, Acc. Chem. Res., 2003, 36, 638; (c) M.-C. Daniel and D.
Astruc, Chem. Rev., 2004, 104, 293; (d) M. A. El-Sayed, Acc. Chem.
Res., 2004, 37, 326; (e) O. Masala and R. Seshadri, Annu. Rev.
Mater. Res., 2004, 34, 41; (f) B. Chaudret, C. R. Phys., 2005, 6, 117;
4
g
(
n
68% yield) of butyl cinnamate 10. The black solid (Pd (2))
was washed with acetonitrile and reused in the next reaction.
(
g) M. Niederberger and G. Garnweitner, Chem.–Eur. J., 2006, 12,
7282; (h) J. P. Wilcoxon and B. L. Abrams, Chem. Soc. Rev., 2006,
5, 1162.
4 (a) M. Moreno-Man
tallics, 2001, 20, 4524; (b) M. Moreno-Man
Villarroya, Chem. Commun., 2002, 60; (c) M. Moreno-Man
Pleixats and M. Tristany, J. Fluorine Chem., 2005, 126, 1435; (d)
For a review see: M. Moreno-Manas and R. Pleixats, in Fluorous
Nanoparticles, in Handbook of Fluorous Chemistry, ed. J. A.
Gladysz, D. P. Curran and I. T. Horvath, Wiley-VCH, Weinheim,
004, ch. 12.2, p. 491; (e) M. Tristany, J. Courmarcel, P. Dieu-
donne, M. Moreno-Manas, R. Pleixats, A. Rimola, M. Sodupe
and S. Villarroya, Chem. Mater., 2006, 18, 716; (f) M. Tristany, B.
Chaudret, P. Dieudinne, Y. Guari, P. Lecante, V. Matsura, M.
Moreno-Manas, K. Philippot and R. Pleixats, Adv. Funct. Mater.,
006, 16, 2008; (g) A. Serra-Muns, R. Soler, E. Badetti, P. de
Mendoza, M. Moreno-Manas, R. M. Sebastian and A. Vallribera,
New J. Chem., 2006, 30, 1584.
For reviews see: (a) R. Schlogl and S. B. A. Hamid, Angew. Chem.,
Suzuki reaction. Typical experimental procedure
3
Phenyl boronic acid (0.323 g, 2.65 mmol), 4-bromoacetophe-
˜
as, R. Pleixats and S. Villarroya, Organome-
as, R. Pleixats and S.
as, R.
˜
none (0.351 g, 1.76 mmol) and Pd
n
(2) (0.008 g, 0.010 mmol)
O 95/5. Then K CO
0.495 g, 3.58 mmol) was added and the mixture was stirred at
˜
were suspended in 3.5 mL of DMF–H
2
2
3
(
˜
1
10 1C during 4 hours. After addition of AcOEt the mixture
(2) and
which was washed with water and acetone. The black
solid Pd (2) was reused in the next cycles. Addition of water to
the organic layer afforded the precipitation of 13, which was
´
was centrifuged. The solid residue was a mixture of Pd
CO
n
2
K
2
3
´
˜
n
´
1
4
˜
filtrated to give 0.315 g (91%) of 4-acetylbiphenyl 13.
2
˜
´
Sonogashira reaction. Typical experimental procedure
5
¨
4
0
1
-Iodoanisole (0.200 g, 0.85 mmol), phenylacetylene (0.10 mL,
.91 mmol), Pd (2) (0.007 g, 0.009 mmol), K CO (0.240 g,
.74 mmol), CuI (0.003 g, 0.016 mmol), PPh (0.004 g, 0.015
Int. Ed., 2004, 43, 1628; (b) J. Grunes, J. Zhu and G. A. Somorjai,
Chem. Commun., 2003, 2257; (c) P. Migowski and J. Dupont,
Chem.–Eur. J., 2007, 13, 32.
n
2
3
3
6
(a) C. A. M Afonso, N. M. T. Louren c¸ o and A. de A. Rosatella,
mmol) and 4 mL of ethanol were stirred at 80 1C during
hours. The mixture was then centrifuged and the residue, a
mixture of Pd (2) and K CO , was reused in the next cycle
Molecules, 2006, 11, 81; (b) E. Hollink and E. E. Simanek, Org.
Lett., 2006, 11, 2293.
˜
7 E. Badetti, M. Moreno-Manas, R. Pleixats, R. M. Sebastian, A.
´
2
n
2
3
(
although some K CO (0.12 g, 8.7 mmol) was added to the
2
Serra, R. Soler and A. Vallribera, Synlett, 2005, 3, 449.
G. G. Yakobson and V. M. Vlasov, Synthesis, 1976, 652.
3
8
9
consecutive reactions). The solution was decanted and some
diethyl ether was added. Then the organic layer was washed
with water, dried and evaporated. The residue was purified by
chromatography through silica-gel using hexanes–ethyl acet-
ate 98/2 as eluent to give 0.127 g (81% yield) of 1-methoxy-4-
(a) K. R. Langille and M. E. Peach, J. Fluorine Chem., 1971,
07; (b) R. D. Chambers, M. J. Seabury and D. L. H. Williams,
4
J. Chem. Soc., Perkin Trans. 1, 1988, 255; (c) Y. Gimbert,
A. Moradpour and C. Merienne, J. Org. Chem., 1990, 55,
5
347.
1
1
0 S. D. Pastor and E. T. Hessell, J. Org. Chem., 1980, 50, 4815.
1 For some reviews see: (a) R. F. Heck, Acc. Chem. Res., 1979, 146;
1
5
(
phenylethynyl)benzene 16.
(
b) R. F. Heck, Org. React., 1982, 27, 345; (c) V. N. Kalinin,
Synthesis, 1992, 12, 413; (d) A. de Meijere and F. E. Meyer, Angew.
Chem., Int. Ed. Engl., 1994, 33, 2379; (e) W. Cabri and I. Candiani,
Acc. Chem. Res., 1995, 28, 2; (f) I. P. Beletskaya and A. V.
Cheprakov, Chem. Rev., 2000, 100, 3009.
Acknowledgements
Financial support from the Ministry of Education and Science
of Spain (Project CTQ-2005-04968/BQU, Consolider Ingenio
12 For some reviews see: (a) A. Suzuki, Pure Appl. Chem., 1991, 63,
4
2
19; (b) A. R. Martin and Y. Yang, Acta Chem. Scand., 1993, 47,
21; (c) A. Suzuki, Pure Appl. Chem., 1994, 66, 213; (d) N. Miyaura
2
010 (CSD2007-00006)) and Generalitat de Catalunya (Project
2
005SGR00305) is gratefully acknowledged. The Ministry of
and A. Suzuki, Chem. Rev., 1995, 95, 2457; (e) A. Suzuki, J.
Organomet. Chem., 1999, 576, 147; (f) J.-P. Corbet and G. Migna-
ni, Chem. Rev., 2006, 106, 2651.
Education and Science of Spain is gratefully acknowledged for
a predoctoral scholarship to S.N.
1
3 For some reviews see: (a) A. Jutand, Pure Appl. Chem., 2004, 76,
5
65; (b) E. Alacid, D. A. Alonso, L. Botella, C. Najera and M. C.
Pacheco, Chem. Rec., 2006, 6, 117; (c) H. Doucet and J.-C. Hierso,
Angew. Chem., Int. Ed., 2007, 46, 834; (d) R. Chinchilla and C.
Najera, Chem. Rev., 2007, 107, 874.
References
1
(a) Modern Fluoroorganic Chemistry, ed. P. Kirsch, Wiley-VCH,
Weinheim, 2004; (b) Organofluorine Chemistry: Principles and
Commercial Applications, ed. R. E. Banks, B. E. Smart and J. C.
Tatlow, Plenum Press, New York, 1994.
14 G. R. Rosa, C. H. Rosa, F. Rominger, J. Dupont and A. L.
Monteiro, Inorg. Chim. Acta, 2006, 359, 1947.
15 P. Li, L. Wang and H. Li, Tetrahedron, 2005, 61, 8633.
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8 | New J. Chem., 2008, 32, 94–98
This journal is ꢀc the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2008