Dendron-functionalized core - shell superparamagnetic nanoparticles: magnetically recoverable and reusable catalysts for suzuki C - C Cross-Coupling reactions

Article abstract of DOI:10.1002/chem.200901866

A metallodendron functionalized with dicyclohexyldiphosphino palladium complex was synthesized. The metallodendron was grafted onto core-shell superparamagnetic nanoparticles (γ-Fe₂)O₃/polymer, 200-500 nm) to give optimal catalytic reactivity in cross-coupling reactions. The grafted nanoparticles were used as recoverable and reusable catalysts for Suzuki C-C cross-coupling reactions. They showed remarkable reactivity towards iodoand bromoarenes under mild condi-tions, and unprecedented reactivity towards chloroarenes. On completion of the catalytic reaction, the catalysts were readily recovered by using a simple magnet to attract the superparamagnetic grafted nanoparticles. Catalysts were recovered more than 25 times with almost no discernable loss of reactivity.

Full text of DOI:10.1002/chem.200901866

DOI: 10.1002/chem.200901866
Dendron-Functionalized Core–Shell Superparamagnetic Nanoparticles:
Magnetically Recoverable and Reusable Catalysts for Suzuki
À
C C Cross-Coupling Reactions
Daniel Rosario-Amorin,[a, b] Xin Wang,[a, b] Manuel Gaboyard,[c] Rodolphe Clꢀrac,[d, e]
Sylvain Nlate,*[a, b] and Karine Heuzꢀ*[a, b]
À
Abstract: A metallodendron function-
alized with dicyclohexyldiphosphino
palladium complex was synthesized.
The metallodendron was grafted onto
core–shell superparamagnetic nanopar-
ticles (g-Fe2O3/polymer, 200–500 nm)
to give optimal catalytic reactivity in
cross-coupling reactions. The grafted
nanoparticles were used as recoverable
and reusable catalysts for Suzuki C C
cross-coupling reactions. They showed
remarkable reactivity towards iodo-
and bromoarenes under mild condi-
tions, and unprecedented reactivity to-
wards chloroarenes. On completion of
the catalytic reaction, the catalysts
were readily recovered by using
a
simple magnet to attract the superpara-
magnetic grafted nanoparticles. Cata-
lysts were recovered more than 25
times with almost no discernable loss
of reactivity.
Keywords: cross-coupling
·
den-
drons · heterogeneous catalysis ·
nanoparticles · supported catalysts
Introduction
polymers.[2] The grafting of such supports with homogeneous
catalysts often provides good catalytic activity together with
possible recovery of the catalyst system by filtration or
liquid/liquid extraction.[3] More recently, new smart supports,
such as superparamagnetic nanoparticles (MNPs), usually
known as ferrofluids, have emerged and have great potential
for catalyst recovery, as the recovery step requires a simple
external magnet. The first example, reported by Lee et al.,[4]
involved magnetic ferrite nanoparticles (CoFe2O4) coated
with a rhodium-based complex catalyst that showed catalytic
activity in hydroformylation of olefins. MNPs[5] have been
widely used in the last few decades in various magnetic devi-
ces[6] and in biomedical applications[7] such as magnetic car-
riers for bioseparation, enzyme and protein immobilization,
and contrast-enhancing media. They can be used neat or
coated with a silica or polymer shell to avoid toxic effects
on biological media.
Over the past few decades, supported catalysts have become
powerful tools for transition metal catalysis, since environ-
mental concerns are favorable to green methodologies com-
patible with the recovery and reuse of the catalyst and the
removal of toxic metals from the reaction medium.[1] In this
context, many efforts have been made to design and synthe-
size recoverable catalysts. Various inorganic and organic
supports have been explored, such as mesoporous silica and
[a] D. Rosario-Amorin, Dr. X. Wang, Dr. S. Nlate, Dr. K. Heuzꢀ
Universitꢀ de Bordeaux, UMR 5255, ISM
351 cours de la libꢀration, Talence, 33405 (France)
Fax : (+33)556-4000-6994
E-mail: k.heuze@ism.u-bordeaux1.fr
[b] D. Rosario-Amorin, Dr. X. Wang, Dr. S. Nlate, Dr. K. Heuzꢀ
CNRS, UMR 5255, ISM, Talence, 33405 (France)
Catalytic functionalization of the MNPs was mainly ach-
ieved by a direct alloying approach (impregnation of transi-
tion metal nanoparticles and superparamagnetic Fe3O4)[8] or
by functionalization of neat MNPs with silane,[9] phosphonic
acid,[10] or carboxylic acid ligands.[11] Another functionaliza-
tion strategy is immobilization of homogeneous catalysts on
core–shell g-Fe2O3 MNPs based on an oxide/polymer[12] or
oxide/silica[13] structure. These nanoparticles are made up of
a magnetic iron oxide core coated by a layer of cross-linked
polymer or silica shell. The organic or inorganic layer stabil-
[c] Dr. M. Gaboyard
Ademtech SA., Parc Scientifique Unitec
4 Allꢀe du Doyen Georges Brus Pessac, 33600 (France)
[d] Dr. R. Clꢀrac
CNRS, UPR 8641, Centre de Recherche Paul Pascal (CRPP)
Equipe “Matꢀriaux Molꢀculaires Magnꢀtiques”
115 avenue du Dr. Albert Schweitzer, Pessac, 33600 (France)
[e] Dr. R. Clꢀrac
Universitꢀ de Bordeaux, UPR 8641, Pessac, 33600 (France)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.200901866.
12636
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 12636 – 12643

FULL PAPER
izes nanoparticles by preventing aggregation of oxide cores
and offers a surface for immobilization of catalysts.
coupling of halogenoarenes and boronic acid compounds.
We demonstrated that it is possible to recover and reuse
these grafted catalysts at least 25 times without significant
loss of reactivity.
Dendrimers[14] are macromolecules developed since the
1990s with a highly branched three-dimensional architecture.
Recently, dendrons or dendrimers have been used as coat-
ings to stabilize MNPs,[15] to investigate protein interac-
tions,[16] and for catalytic applications.[17,18] Previously, we ex-
plored the ability of dendronized molecules to increase the
surface functionalization of MNPs through fluorescent den-
drons grafted onto core–shell g-Fe2O3/polymer 300 nm
MNPs.[19] The dendron-functionalized core–shell MNPs were
generally synthesized by a divergent route wherein the den-
dron was built step by step on the MNP surface. Surprising-
ly, only few examples of convergent routes using well-de-
fined dendrons synthesized and characterized before their
grafting onto the MNP surface have been reported in the lit-
erature.[16,20] Here we report the synthesis of a dendron bear-
ing catalytic groups (diphosphino palladium(II)-based com-
plexes) on one side and a primary amino group at the focal
point for grafting onto core–shell g-Fe2O3/polymer MNPs.
Grafting of the metallodendrons onto core–shell g-Fe2O3/po-
lymer 300 nm MNPs was performed and optimized by a con-
vergent approach. These functionalized MNPs were used as
magnetically recoverable and reusable catalysts in Suzuki
Results and Discussion
Synthesis of Pd-complex-functionalized dendron 9: We pre-
pared tris[NACTHNUTRGNEUNG
(PCy2)2PdII] dendron 9 with a primary amino
group at the focal point necessary for grafting onto core–
shell MNPs as described in Scheme 1. The first step was to
prepare methoxyphenyl triol 2 by oxidative hydroboration
of the terminal olefin groups of triallyl compound 1.[21] Hy-
droboration/oxidation of the allyl groups of 1 gave triol 2,
treatment of which with NaI in the presence of Me3SiCl
gave tris(iodoalkyl) phenol dendron 3. Treatment of 3 with
NaN3 yielded triazido phenol dendron 4, which was coupled
with iodo compound 12 to generate 5. Spacer group 12 was
obtained from Teoc-protected amino alcohol 11, prepared
from commercially available 6-aminohexanol (10). Catalytic
reduction of 5 gave triamine 6. Aminophosphine dendron 7
was then obtained by phosphinomethylation of 6, as report-
ed for dendrimer analogues.[22] Deprotection of the terminal
Scheme 1. Synthesis of dendron 9. Reagents and conditions: i) HB
MeCN, 72 h, 808C; iv) NaN3, DMF, 15 h, 408C; v) KOH, DMF, 4 h, RT; vi) H2, Pd/C, MeOH, 5 h, RT; vii) HCHO, HPCy2, MeOH, toluene, 12 h, 708C to
RT; viii) Bu4NF, THF, 5 h, 608C; ix) Pd(OAc)2, CH2Cl2, 2 h, RT; x) Teoc-OC6H4-NO2, Et3N, CH2Cl2, 2 h, RT; xi) MeSO2Cl, Et3N, CH2Cl2, 2 h, RT;
xii) NaI, MeCN, 24 h, RT. sia=3-methyl-2-butyl, Teoc=2-(trimethylsilyl)ethoxycarbonyl.
(sia)2, THF, 24 h, À158C to RT; ii) H2O2, NaOH, H2O, 24 h, 508C; iii) Me3SiCl, NaI,
AHCTUNGTRENNUNG
Chem. Eur. J. 2009, 15, 12636 – 12643
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
12637

K. Heuzꢀ, S. Nlate et al.
amino group with Bu4NF gave dendron 8. Complexation of
the phosphine groups of 8 with PdII led to metallodendron 9
in all cases preliminary dissolution of the dendrons in DMF
(30 mm) was necessary in order to improve their solubility
in the grafting medium. If the colloidal state of particles was
better in a diluted medium,[29] the grafting reaction was im-
proved in that medium.
bearing three NACHTUNGTRENNUNG
(PCy2)2PdII catalytic groups. Completion of
the reaction was followed by 31P NMR spectroscopy by
monitoring disappearance of the free phosphine signal at
d=À18.3 ppm and appearance of that of the coordinated
phosphine at d=26.7 ppm. Dendron 9 is stable towards
moisture, but was stored under nitrogen to avoid degrada-
tion of the Pd complex.
We have also studied the effect of the coupling agent in
the grafting efficiency. Carboxyl groups at the MNP surface
are usually activated by an excess of carbodiimide along
with N-hydroxysuccinimide (NHS) to avoid hydrolysis of O-
acyl isourea intermediates. We tested two carbodiimides:[30]
N-cyclohexyl-N’-(2-morpholinoethyl) carbodiimide methyl-
p-toluenesulfonate (CHMC) and N-(3-dimethylaminoprop-
yl)-N-ethylcarbodiimide hydrochloride (EDC), with or with-
out NHS, in MeOH/Tx under the grafting conditions de-
scribed in Table 1. Interestingly, CHMC and EDC gave basi-
cally the same result,[31] but the use of NHS[32] led to difficul-
ties such as low magnetic susceptibility of the MNPs to an
external magnet field during the washing step at the end of
the grafting reaction, with a notable loss of particles. There-
fore, we selected CHMC as coupling agent for the grafting
reactions.
Grafting of dendrons onto MNPs: Dendron 9 was covalently
grafted onto MNPs. Core–shell g-Fe2O3/polymer 300 nm su-
perparamagnetic
nanoparticles
(Carboxyl-Adembeads
300 nm, Ademtech, France, 300 mmol COOH/g of particles)
were used as MNPs.[23] The grafting method was reported
previously.[19] However, in the present work we optimized
the grafting conditions (solvent, dilution, etc.) by taking into
account the solubility of metallodendron 9 bearing pallado
phosphine groups.
Grafting of 9 onto core–shell g-Fe2O3/polymer was based
on the peptide reaction between the terminal primary
amino group of 9 and the carboxyl groups of the MNP poly-
mer shell. Coupling was carried out in the presence of cou-
pling agents at room temperature overnight and usually in
aqueous media. We have tested the grafting reaction in vari-
ous solvents (Table 1). The grafting efficiency was estimated
by means of a Suzuki catalytic reaction.[24] In DMF, we ob-
served aggregation of MNPs and low catalytic activity
(Table 1, entry 1). Similarly, in an aqueous medium with a
nonionic surfactant such as Pluronic F127 (PF127)[25] or
PF127/Mes[26] we observed macroscopic aggregation and no-
table precipitation of the dendron to give a heterogeneous
medium and low catalytic activity (Table 1, entries 4 and 5).
Nevertheless, optimal grafting steps were achieved in an
aqueous medium in the presence of nonionic surfactant with
a lower hydrophilic–lipophilic balance,[27] such as triton
X405 (Tx;[28] Table 1, entry 3) or in an organic/aqueous
medium with MeOH/Tx (1/2; Table 1, entry 2). In these
cases, an optimal colloidal state and optimal catalytic activi-
ty of the resulting grafted MNPs were observed. However,
Afterwards, the surface functionalization of the MNPs
was optimized with respect to increasing the dendron load-
ing from 2 to 25 equiv, based on the accessible free carboxyl
groups at the polymer shell.[33] The grafting efficiency was
then estimated by means of a catalytic Suzuki reaction
(Figure 1). Substrates and conditions were chosen to give
Table 1. Grafting conditions:[a] influence of the solvent.
Entry
Grafting solvent
Catalytic reaction[b]
reaction conversion
time [h]
[%]
Figure 1. Catalytic activity of MNPs grafted with dendron
9 versus
number of equivalents of dendron 9 used in the grafting reaction. Cata-
lytic reactions were performed with 0.125 mg of MNP according to the
general procedure (see Experimental Section).
1
2
3
4
5
DMF
2
16
94
93
72
59
MeOH/Tx[c] (1/2)
Tx[c]
0.5
0.5
1
PF127[d]
PF127/Mes[e]
2.5
[a] Grafting was carried out with Carboxyl-Adembeads 300 nm and den-
dron 9 (4 equiv) in DMF with CHMC as coupling agent at RT for 16 h.
Then particles were washed with NaOH (10 mm), Tx, and THF/H2O (2/
1). [b] See ref. [24]. [c] Tx: triton X405 aqueous solution (0.21 wt%) ob-
tained from triton X405 (70 wt%, Aldrich). [d] PF127: Pluronic F127
aqueous solution (0.3 wt%) obtained from Pluronic F127 (Aldrich).
[e] 2-(N-Morpholino)ethanesulfonic acid (50 mm) in an aqueous solution
of PF127.
appropriate reaction times to detect notable variations in
catalytic activity. Inductively coupled plasma (ICP) analysis
showed an effective degrees of grafting of 24 and 60% for 2
and 10 equivalents of dendron 9, respectively.[34] Therefore,
10 equivalents of dendron 9 were used to investigate the cat-
alytic performance of this MNP grafted catalyst.
12638
www.chemeurj.org
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 12636 – 12643

Core–Shell Superparamagnetic Nanoparticles
FULL PAPER
À
Table 3. Catalytic activity of MNPs grafted with dendron 9 in Suzuki re-
actions.
Catalytic performances of dendron-grafted MNPs in C C
cross-coupling reactions: The catalytic activity of grafted
Entry Aryl
halide
Aryl boronic Cat.
Reaction Conversion
time [h] [%]
À
MNPs was investigated in Suzuki C C cross-coupling reac-
acid
G
tion between halo arenes and phenyl boronic acid com-
pounds. Classic reaction conditions[35] were used, except for
the solvent, since THF/H2O was retained during the grafting
procedures. A THF/Tx (1/9) mixture was used instead of
THF/H2O (2/1) to keep nanoparticles perfectly dispersed in
the reaction medium. The MNP catalyst in THF/H2O (2/1)
gave good results up to the first four cycles using recovered
catalyst. Then the reactivity decreased rapidly in terms of
the reaction time needed to obtain total conversion
(Table 2). Also, in THF/H2O we observed progressive aggre-
gation of the particles with increasing number of recovery
Pd][d]
1
2
2.4
1
5
100[a]
95[a]
0.12
3
4
2.4
2.4
4
4
>99[b]
92[b]
5
2.4
4
94[b]
Table 2. Catalytic activity of grafted MNPs in the Suzuki reaction of io-
dobenzene and phenylboronic acid at 308C and 3 mol% Pd.
6
7
8
2.4
2.4
2.4
4
1
1
>99[b]
100[b]
100[b]
Cycle[a]
Solvent THF/H2O (2/1)
Solvent THF/Tx (1/9)
reaction
time [h]
conversion
[%]
reaction
time [h]
conversion
[%]
1
2
3
4
5
6
1.5
4.5
14
8.5
38.5
90
100
80
100
86
85
77
1
2.5
2
1.5
1.5
2
100
100
96
94
96
9
2.4
2.4
1
4
93[b]
92[b]
10
90
[a] Grafting was carried out with Carboxyl-Adembeads 300 nm and den-
dron 9 (see Experimental Section, and Table 4, entry 2). Then particles
were washed with NaOH (10 mm), Tx, and THF/H2O (2/1).
11
12
2.4
2.4
12
12
79[b]
88[b]
steps. In the THF/Tx mixture, Tx preserves the colloidal
state of the particles, and THF is necessary for solubility of
the grafted dendron. Thus, in choosing the reaction solvent,
we need to strike a fine balance between the solubility of
the organic wedge of the particle and aggregation of the par-
ticles.
13
14
4.8
4.8
24
6
50[c]
79[c]
15
4.8
24
29[c]
This result highlights the importance of the colloidal state
of the MNPs during the catalytic processes. The catalytic ac-
tivity of grafted MNPs was tested in the Suzuki coupling re-
action between iodo-, bromo-, and chlorobenzene deriva-
tives and phenyl boronic acids (Table 3). The catalytic activi-
ty of MNPs with iodobenzene (Table 3, entries 1 and 2) was
quantitative, even with ortho-substituted phenylboronic acid
and low catalyst loading (0.12 mol% Pd). In the case of
bromo derivatives (Table 3, entries 3–12), high reactivity
(quantitative yields) was also found, even with ortho-substi-
tuted substrates (Table 3, entries 11 and 12). In contrast to
bromo- and iodobenzene derivatives, the reactivity of chlori-
nated substrates (Table 3, entries 13–15) was lower but still
significant, since we obtained 79% yield with p-chloroaceto-
phenone (Table 3, entry 14). In fact, chlorinated derivatives
seem to be adsorbed onto the MNP surfaces, so THF/Tx (2/
1) was used instead of THF/Tx (1/9) to minimize the extent
of this side phenomenon but with slight negative effect on
the reactivity.
[a] Reaction conditions: see Experimental Section, T=308C. [b] Re-
action conditions: see Experimental Section, T=658C. [c] Reaction con-
ditions: see Experimental Section, T=658C, solvent THF/Tx (2/1).
[d] Grafted MNPs with 10 equiv of dendron 9 were used (see Experimen-
tal Section and Table 4, entry 4).
MNPs (see above). Grafting conditions were optimized by
means of experimental curves of catalytic activity of MNPs
grafted with dendron 9 versus number of equivalent of den-
dron 9 used in the grafting reaction (see Supporting Infor-
mation, Figure S1). Similar to 300 nm MNPs, the best graft-
ing of 200 nm MNPs was obtained with 10 equiv of den-
drons,[37] in contrast to 500 nm MNPs, which aggregate
above 8 equiv of dendron 9. Catalytic activities of 200 and
300 nm MNPs were nearly the same (Figure 2).[38] Thus, no
discernable effect of particle size was detected in the frame-
work of the catalytic activity study.
Furthermore, 200 and 500 nm MNPs[36] were grafted with
dendron 9 by using the procedure described for 300 nm
Chem. Eur. J. 2009, 15, 12636 – 12643
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
12639

K. Heuzꢀ, S. Nlate et al.
Figure 4. Recovery experiments on grafted MNPs. Grafting conditions:
see Experimental Section and Table 4, entry 1. Reaction conditions: see
Experimental Section for grafted MNP materials (5 mg, 1.96 mol% Pd),
phenylboronic acid, and iodobenzene. The mixture was stirred for 1 h at
658C.
Figure 2. Catalytic reactions were performed with 0.125 mg of 200 or
300 nm grafted MNPs.
Recovery of dendron-grafted MNPs: Using surface-modified
magnetic nanoparticles as catalyst support ensures minimal
loss, easy and soft separation, and reusability of the catalyst
at the end of each reaction cycle. Indeed, after each cycle,
the metallodendritic catalyst was separated from the reac-
tant by magnetic separation. Then the catalyst was washed
several times with THF/Tx and reused in the next catalytic
cycle (Figure 3). Recovery experiments were performed for
the coupling reaction between iodobenzene and phenyl bor-
onic acid in the presence of 300 nm MNPs grafted with den-
dron 9 (Figure 4).[39] They revealed almost no significant loss
of activity even after 25 cycles of recovery. These results in-
dicate good stability of the catalyst, in contrast to the pre-
cipitation technique used in previous work.[22b–e] The slight
decrease (<5%) of reactivity observed after 25 cycles was
probably due to the recovery technique (slight loss of parti-
cles during the magnetic separation process) and the leach-
ing of Pd often observed in such catalytic species, and this
was confirmed by ICP analysis of the supernatent after the
catalytic reaction (0.36% loss of Pd/cycle, i.e., 14 ppm of Pd
in the crude product).
Conclusions
We have synthesized an AB3 metallodendron funtionalized
by catalytic groups (diphosphino palladium(II) complexes)
on one side and a primary amino group at the focal point.
Grafting of this dendron onto core–shell g-Fe2O3/polymer
300, 200, and 500 nm MNPs was studied and optimized by a
convergent approach. The catalytic activity of this supported
À
catalyst towards Suzuki C C cross-coupling reactions be-
tween halogenoarenes and boronic acid compounds was in-
vestigated. The presence of the chelating diphosphines on
the dendron is necessary for the stability and a key feature
for their efficiency. Indeed, we obtained highly active cata-
lysts for a range of iodo- and bromobenzene derivatives and
an unprecedented reactivity towards chloroarenes by using
core–shell g-Fe2O3 grafted MNP catalysts. Finally, we
showed that it is easy to recover and reuse this grafted cata-
lyst at least 25 times without any significant loss of reactivi-
ty. In addition, the grafted catalyst is environmentally
friendly because of its low extent of Pd leaching 0.36%
(14 ppm of Pd in crude product) after each catalytic reac-
tion.
Experimental Section
All reactions were performed under a nitrogen atmosphere in standard
glassware (Schlenk use for 7, 8, and 9). The starting materials were ob-
tained commercially and used without further purification. The solvents
were dried according to standard procedures and saturated with nitrogen.
The 1H, 13C, and 31P NMR spectra were recorded on the following spec-
trometers: Bruker DPX 200 FT NMR spectrometer (1H: 200.16, 13C:
Figure 3. Magnetic separation of a grafted MNP catalyst in solution
(THF/Tx 1/9) by an external magnet. Particles come close to the vial wall
and supernatant can be removed.
12640
www.chemeurj.org
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 12636 – 12643

Core–Shell Superparamagnetic Nanoparticles
FULL PAPER
50.33, 31P: 81.02 MHz), Bruker AC 250 FT NMR spectrometer (1H:
250.13, 13C: 62.90 MHz), and Bruker Avance 300 FT NMR spectrometer
(1H: 300.13, 13C: 75.46, 31P: 121.49 MHz). Chemicals shifts are reported in
parts per million (d) against referenced solvent signals. Mass spectra
were performed by CESAMO (Bordeaux, France) on a QStar Elite mass
spectrometer (Applied Biosystems). The instrument is equipped with an
ESI source and spectra were recorded in negative or positive mode.
MALDI-TOF spectra were performed by CESAMO (Bordeaux, France)
on a Voyager mass spectrometer (Applied Biosystems). The instrument
is equipped with a pulsed N2 laser (337 nm) and a time-delayed extract-
ed-ion source. Spectra were recorded in positive-ion mode by using a re-
flectron and with an accelerating voltage of 20 kV. Elemental analyses
were carried out in elemental analysis department at CNRS-Vernaison,
France. GC spectra were recorded with a Varian star 3900 gas chromato-
graph equipped with a fused-silica capillary column heated gradually to
2508C (from 408C, rate 108CminÀ1) with He as vector gas at a column
head pressure of 10 psi, or with a Varian star 3400 gas chromatograph
equipped with a fused-silica column heated gradually to 2208C (from
408C, rate 108CminÀ1) with N2 as vector gas and a column head pressure
of 5 or 10 psi An FID detector was used. Yields were calculated by an in-
tegration of product peaks (Star chromatography workstation 5.50) after
determination of the response coefficient of each product versus each
chloroarene reagent. For column chromatography, Merck silica gel 60
(230–400 mesh) was used. Compound 9 was synthesized in ten steps from
known methoxyphenyl triallyl compound 1 and spacer compound 12.
Synthesis of 2 and 3 has been previously described.[21]
CH3Si); 13C NMR (CDCl3): d=156.8 (d, 2C, COAr +C=O), 138.9 (s,1C,
C
q(Ar)), 127.3 (s, 2C, CH(Ar)), 113.9 (s, 2C, CH(Ar)), 67.6 (s, 1C, CH2O),
62.8 (s, 1C, CH2OCO), 42.8 (s, 3C, CH2NH2), 42.0 (s, 1C, CqCAr), 40.8 (s,
1C, CH2NH), 34.8 (s, 3C, CH2Cq), 30.0 (s, 1C, CH2CH2NH), 29.3 (s, 1C,
CH2CH2O), 27.7 (s, 3C, CH2), 26.5 (s, 1C, CH2), 25.8 (s, 1C, CH2), 17.8
(s, 1C, CH2Si), À1.4 ppm (s, 3C, CH3Si); MS (ESI): m/z: [M+H] calcd
523.40, found 523.40.
p-TeocNHCATHNUGTERN(NNUG CH2)6OACHUTNRTGEG(NNUN C6H4)CH{CH2CH2CH2NACTHNGUTREN(NUGN CH2PCy2)2}3 (7): A solution
of 10% dicyclohexylphosphine (22.7 mL, 11.2 mmol) in hexane was intro-
duced into a Schlenk tube and evaporated under reduced pressure. A so-
lution of paraformaldehyde (1.8 g, 60.0 mmol) in MeOH/toluene (2/1,
10 mL) was added under inert atmosphere, and the reaction mixture
heated at 708C for 10 min. A solution of 6 (0.8 g, 1.54 mmol) in MeOH/
toluene (2/1, 10 mL) was added, and the mixture stirred at 708C for
10 min and then at room temperature for 12 h. The volume of the reac-
tion mixture was reduced and MeOH (20 mL) added. The residue was
isolated from the medium, washed several times with MeOH, and dried
1
under vacuum to yield 7 as a glassy colorless solid (2.1 g, 78%). H NMR
(CDCl3): d=7.13 (d, 2H, CH(Ar)), 6.75 (d, 2H, CH(Ar)), 4.58 (br, 1H,
NH), 4.13 (t, 2H, CH2OCO), 3.86 (t, 2H, CH2O), 3.15 (q, 2H, CH2NH),
2.67 (s, 12H, NCH2P) 2.59 (t, 6H, CH2NCH2P), 1.7–1.1 (m, 152H), 0.95
(t, 2H, CH2Si), 0.02 ppm (s, 9H, CH3Si); 13C NMR (CDCl3): d=156.9 (d,
2C, CO(Ar) +C=O), 139.3 (s, 1C, Cq(Ar)), 127.6 (s, 2C, CH(Ar)), 113.7 (s,
2C, CH(Ar)), 67.6 (s, 1C, CH2O), 62.9 (s, 1C, CH2OCO), 56.7 (s, 3C,
CH2NCH2P), 52.4 (s, 6C, CH2P) 42.6 (s, 1C,
CArCq), 41.0 (s, 1C,
CH2NH), 35.6 (s, 3C,CH2Cq), 32.9 (d, 12C, PCH(Cy)), 29.8 (dd, 24C,
CH2(Cy)), 27.5 (s, 24C, CH2(Cy)), 26.7 (s, 12H,CH2(Cy)), 26.0 (s, 1C, CH2),
17.9 (s, 1C, CH2Si), À1.3 ppm (s, 3C, CH3Si); 31P NMR (CDCl3): d=
À18.2 ppm; MS (MALDI-TOF): m/z (%): product also appeared in oxi-
dized forms (
1–6O) due to the matrix and experimental conditions: [M+Na] (17)
calcd: 1807.31, found: 1807.29; [M+O+Na] (45) calcd: 1822.30, found:
1822.28; [M+2O+Na] (100) calcd: 1838.30, found: 1838.28;
[M+3O+Na] (61) calcd: 1854.29, found: 1854.27; [M+4O+Na] (35)
calcd: 1870.29, found: 1870.27; [M+5O+Na] (14) calcd: 1886.28, found:
1886.28; [M+6O+Na] (10) calcd: 1902.28, found: 1902.27.
p-OHACHTUNGTRENNUNG(C6H4)CH(CH2CH2CH2N3)3 (4): A mixture of 3 (4.95 g, 8.1 mmol)
and NaN3 (7.89 g, 121 mmol) was stirred in DMF (11 mL) at 408C for
24 h under nitrogen atmosphere. Water (15 mL) was then added and the
mixture extracted with Et2O (3ꢂ20 mL). Organic layers were gathered,
washed with water (10ꢂ20 mL), and dried over anhydrous Na2SO4. Sol-
vent was removed under reduced pressure to afford 4 as a brown oil
(2.67 g, 92% yield). 1H NMR (CDCl3): d=7.14 (d, 2H, CH(Ar)), 6.80 (d,
2H, CH(Ar)), 4.93 (br, 1H, OH), 3.23 (t, 6H, CH2N3), 1.66 (m, 6H, CH2),
1.35 ppm (m, 6H, CH2); 13C NMR (CDCl3): d=153.9 (s, 1C, C(Ar)O),
138.0 (s, 1C, Cq(Ar)), 127.4 (s, 2C, CH(Ar)), 115.3 (s, 2C, CH(Ar)), 52.0 (s,
3C, CH2N3), 42.5 (s, 1C, CqC(Ar)), 34.4 (s, 3C, CH2Cq), 23.3 ppm (s, 3C,
CH2CH2N3); elemental analysis calcd (%) for C16H23N9O (357.41): C
53.8, H 6.5; found: C 54.5, H 6.6.
p-NH2CATHNUGNERTN(NGU CH2)6OACHTNUEGTRUNN(GN C6H4)CH{CH2CH2CH2NACHTUNGRTEN(NUGN CH2PCy2)2}3 (8): A mixture of 7
(1.79 g, 1.0 mmol), tetrabutylammonium fluoride 1m in THF (10 mL,
10.0 mmol), and THF (3 mL) was stirred under inert atmosphere at 608C
for 5 h. Then the solvent was removed under reduced pressure and the
residue washed several time with iced methanol. The product was dried
under vacuum to give 8 as a white powder (1.3 g, 82%). 1H NMR
(CDCl3): d=7.13 (d, 2H, CH(Ar)), 6.76 (d, 2H, CH(Ar)), 3.87 (t, 2H,
CH2O), 2.68 (s, 12H, NCH2P) 2.59 (t, 8H, CH2NCH2P+CH2NH2), 1.7–
1.1 ppm (m, 152H); 13C NMR (CDCl3): d=156.65 (s, 1C, COAr), 139.3 (s,
1C, Cq(Ar)), 127.5 (s, 2C, CH(Ar)), 113,6 (s, 2C, CH(Ar)), 67.7 (s, 1C,
CH2O), 56.8 (s, 3C, CH2NCH2P), 52.3 (s, 6C, CH2P) 42.5 (s, 2C, CArCq +
CH2NH2), 35.5 (s, 3C, CH2Cq), 33.0 (d, 12C, PCH(Cy)), 29.8(dd, 24C,
CH2(Cy)), 27.5 (s, 24C, CH2(Cy)), 26.7 (s, 12H, CH2(Cy)), 20.3 ppm (s, 6C,
CH2); 31P NMR (CDCl3): d=À18.3 ppm (PCy2); MS (MALDI-TOF): m/
z: product appeared in oxidized form due to the matrix and experimental
conditions: [M+6O+Na] calcd: 1758.22, found: 1758.15.
p-teocNHACHTUNGTRENNUNG(CH2)6OACHTUNGTRENNUNG(C6H4)CH(CH2CH2CH2N3)3 (5): Triazo dendron 4
(590 mg, 1.65 mmol) and KOH (280 mg, 4.96 mmol) were dissolved in
dry DMF (2 mL) in a Schlenk tube and stirred for 20 min. A solution of
Teoc-protected 6-iodo-1-aminohexane 12 (613 mg, 1.65 mmol) in DMF
(1 mL) was added to the reaction mixture, which was stirred at room
temperature for 4 h. Water was added and the product extracted with
Et2O. The organic layer was washed several times with water, dried over
MgSO4, and evaporated under reduced pressure to give 5 as a brown oil
(0.91 g, 92%). 1H NMR (CDCl3): d=7.17 (d, 2H, CH(Ar)), 6.84 (d, 2H,
CH(Ar)), 4.61 (br, 1H, NH), 4.14 (t, 2H, CH2OCO) 3.93 (t, 2H, CH2O),
3.22 (t+q, 8H, CH2NH+CH2NH2), 1.74–1.26 (m, 20H, CH2), 0.97 (t,
2H, CH2Si), 0.03 ppm (s, 9H, CH3Si); 13C NMR (CDCl3): d=157.2 (s,
1C, C=O), 156.9 (s, 1C, COAr), 137.4 (s, 1C, Cq(Ar)), 127.2 (s, 2C, CH(Ar)),
114,3 (s, 2C, CH(Ar)), 67.7 (s, 1C, CH2O), 62.9 (s, 1C, CH2OCO), 52.0 (s,
3C, CH2N3), 42.0 (s, 1C, CqCAr), 40.9 (s, 1C, CH2NH), 34.5 (s, 3C,
CH2Cq), 30.1 (s, 1C, CH2CH2NH), 29.3 (s, 1C, CH2CH2O), 26.6 (s, 1C,
CH2), 25.9 (s, 1C, CH2), 23.3 (s, 3C, CH2), 17.8 (s, 1C, CH2Si), À1.4 ppm
(s, 3C, CH3Si); MS (ESI): m/z (%): [M+Na] (100) calcd 623.36; found:
623.36.
p-NH
G
N
ACTHGNUETRN(NNUG CH2 PCy2)2PdACHTUNGTRNEN(UNG OAc)2}3 (9): A
mixture of
8
1.83 mmol) was stirred in CH2Cl2 (15 mL) at room temperature under
inert atmosphere for 2 h. Then the mixture reaction was evaporated and
the product dried under vacuum to give 9 as a dark brown powder (1.4 g,
quant.). 1H NMR (CDCl3, 258C): d=7.13 (d, 2H, CH(Ar)), 6.80 (d, 2H,
CH(Ar)), 3.84 (t, 2H, CH2O), 2.48–2.2 (m, 20H, NCH2P+CH2NCH2P+
CH2NH2), 1.94 (s, 12H, CH3COO), 1.7–1.1 (m, 152H, CH2); 13C NMR
(CD2Cl2): d=177.6 (m, 6C, CO(Ac)), 157.2 (s, 1C, COAr),139.0 (s, 1C,
p-TeocNHACHTUNGTRENNUNG(CH2)6OACHTUNGTRENNUNG(C6H4)CH(CH2CH2CH2NH2)3 (6): A mixture of 5
(900 mg, 1.49 mmol) and Pd/C (330 mg, 0.31 mmol) in dry MeOH
(10 mL) under H2 atmosphere (1.5–2 bars) was stirred at room tempera-
ture for 5 h. The mixture was filtered through Celite and the solvent was
removed under reduced pressure. The product was dried under vacuum
C
q(Ar)), 127.1 ppm (s, 2C, CH(Ar)), 114.0 (s, 2C, CH(Ar)), 67.6 (s, 1C,
1
CH2O), 63.3 (s, 3C, CH2NCH2P), 48.7 (s, 6C, CH2P) 42.7 (s, 2C, CArCq +
CH2NH2), 36.0 (m, 9C, CH2Cq +CH3(Ac)), 29.7(m, 12C, PCH(Cy)), 29.8 (s,
24C, CH2(Cy)), 26.9 (s, 24C, CH2(Cy)), 25.9 (s, 12H,CH2(Cy)), 19.7 ppm (s,
6C, CH2); 31P NMR (CDCl3): d=26.7 ppm; MS (MALDI-TOF): m/z
(%): product appeared in oxidized form due to the matrix and experi-
to afford 6 as alight yellow oil (678 mg, 87%). H NMR (CDCl3): d=7.13
(d, 2H, CH(Ar)), 6.75 (d, 2H, CH(Ar)), 4.84 (br, 1H, NH), 4.11 (t, 2H,
CH2OCO), 3.86 (t, 2H, CH2O), 3.10 (q, 2H, CH2NH), 2.56 (t, 6H,
CH2NH2), 1.71 (q, 2H, CH2CH2O), 1.56 (m, 6H, CH2), 1.5–1.20 (m, 6H,
CH2CH2CH2), 1.14 (m, 6H,CH2), 0.91 (t, 2H, CH2Si), À0.02 ppm (s, 9H,
Chem. Eur. J. 2009, 15, 12636 – 12643
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
12641

K. Heuzꢀ, S. Nlate et al.
mental conditions [M+4O+H] (95%): calcd: 2376.04, found: 2377.04;
[M+5O+H] (100%): calcd: 2392.03, found: 2392.97.
THF/Tx (1/9, 2ꢂ500 mL). Then they were introduced into a freshly made
reaction mixture.
Teoc-NHACHTUNGTRENNUNG(CH2)6OH (11): Triethylamine (2.9 mL, 21.1 mmol) was added
to a solution of 6-aminohexan-1-ol (10, 1.25 g, 10.66 mmol) in CH2Cl2
(5 mL) under inert and dry atmosphere. The mixture was stirred at room
temperature for 10 min and a solution of 4-nitrophenyl 2-(trimethylsilyl)-
ethyl carbonate (3 g, 10.59 mmol) in CH2Cl2 (5 mL) was then added. The
reaction mixture was stirred at room temperature for 2 h and dried to
remove triethylamine. The crude product was extracted with CH2Cl2
(40 mL) and the organic layer washed several times with brine and
NaHCO3, and with an aqueous solution of NaOH (2n) until the organic
layer became colorless. The organic layer was dried over anhydrous
Na2SO4, and the solvent removed under reduced pressure to give a light
Acknowledgements
Financial support from the Universitꢀ de Bordeaux 1, Centre National de
la Recherche Scientifique, the Region Aquitaine, the Ministꢃre de l’En-
seignement Supꢀrieur et de la Recherche (DRA), and the Agence Natio-
nale de la Recherche (ANR-05-JCJC-0245) is gratefully acknowledged.
1
yellow oil (2.40 g, 86.7%). H NMR (CDCl3): d=4.67 (br, 1H, NH), 4.12
[1] J. H. Clark, D. J. Macquarrie, Handbook of Green Chemistry and
Technology; Blackwell, Oxford, 2002.
(t, 2H, 8.4 Hz, CH2OCO), 3.61 (t, 2H, 6.4 Hz, CH2OH), 3,14 (q, 2H,
CH2NH), 1.78 (br, 1H, OH/NH), À1.33 (m, 8H, CH2 ꢂ4), 0.95 (t, 8.5 Hz,
2H, CH2Si), 0.01 ppm (s, 9H, CH3Si); 13C NMR (CDCl3): d=157.01 (s,
1C, C=O), 62.57 (s, 2C, CH2OCO+CH2OH), 40.75 (s, 1C, CH2NH),
32.58 (s, 1C, CH2), 30.03 (s, 1C, CH2), 26.42 (s, 1C, CH2), 25.38 (s, 1C,
CH2), 17.8 (s, 1C, CH2Si), 6.9 (s, 1C, CH2I), À1.43 ppm (s, 3C, CH3Si);
MS (ESI): m/z (%): calcd 284.166, found 284.166 (93) [M+Na], 545.342
(100) [2m+Na].
[2] a) A. Corma, H. Garcia, Adv. Synth. Catal. 2006, 348, 1391; b) F.
Cozzi, Adv. Synth. Catal. 2006, 348, 1367; c) B. M. L. Dioos, I. F. J.
Vankelecom, P. A. Jacobs, Adv. Synth. Catal. 2006, 348, 1413; d) N.
Madhavan, C. W. Jones, M. Weck, Acc. Chem. Res. 2008, 41, 1153;
e) V. Polshettiwar, A. Molnꢄr, Tetrahedron 2007, 63, 6949.
[3] D. E. Bergbreiter, S. D. Shung, Adv. Synth. Catal. 2006, 348, 1352.
[4] a) T. J. Yoon, W. Lee, Y. S. Oh, J. K. Lee, New J. Chem. 2003, 27,
227; b) T. J. Yoon, J. I. Kim, J. K. Lee, Inorg. Chim. Acta 2003, 345,
228.
[5] a) I. Y. Goon, L. M. H. Lai, M. Lim, P. Munroe, J. J. Gooding, R.
Amal, Chem. Mater. 2009, 21, 673; b) A. H. Latham, M. E. Williams,
Acc. Chem. Res. 2008, 41, 411; c) L. Wang, H.-Y. Park, S. I.-I. Lim, J.
Schadt, D. Mott, J. Luo, X. Wang, C.-J. Zhong, J. Mater. Chem. 2008,
18, 2629; d) A.-H Lu, E. L. Salabas, F. Schꢅth, Angew. Chem. 2007,
119, 1242; Angew. Chem. Int. Ed. 2007, 46, 1222; e) U. Jeong , X.
Teng, Y. Wang, H. Yang, Y. Xia, Adv. Mater. 2007, 19, 33; f) H.-B.
Xia, J. Yi, P.-S. Foo, B. Liu, Chem. Mater. 2007, 19, 4087; g) Y.-W.
Jun, J. S. Choi, J. Cheon, Chem. Commun. 2007, 1203.
[6] a) K. Furumura, H. Sugi, Y. Murakami, H. Asai, US Patent 4598914,
1986; b) J. A. King, US 4017694, 1977; c) D. H. Han, H. L. Luo, Z.
Yang, J. Magn. Magn. Mater. 1996, 161, 376; H. Fujiwara, J. Appl.
Phys. 1993, 73, 5757; d) Q. Song, Z. J. Zhang, J. Am. Chem. Soc.
2004, 126, 6164; e) H. Zeng, J. Li, J. P. Liu, Z. L. Wang, S. Sun,
Nature 2002, 420, 395; f) C. Liu, B. Zou, A. J. Rondinone, Z. J.
Zhang, J. Am. Chem. Soc. 2000, 122, 6263.
[7] a) S. Laurent, D. Forge, M. Port, A. Roch, C. Robic, L. Vander Elst,
R. N. Muller, Chem. Rev. 2008, 108, 2064; b) Y.-W. Jun, J. W. Seo, J.
Cheon, Acc. Chem. Res. 2008, 41, 179; c) H.-Y. Park, M. J. Schadt,
L. Wang, I.-I. S. Lim, P. N. Njoki, S. H. Kim, M.-Y. Jang, J. Luo, C.-J.
Zhong, Langmuir 2007, 23, 9050; d) M. I. Shukoor, F. Natalio, M. N.
Tahir, V. Ksenofontov, H. A. Therese, P. Theato, H. C. Schrçder,
W. E. G. Mꢅller, W. Tremel, Chem. Commun. 2007, 4677; e) P.
Drake, H.-J. Cho, P.-S. Shih, C.-H. Kao, K.-F. Lee, C.-H. Kuo, X.-Z.
Lin, Y.-J. Lin, J. Mater. Chem. 2007, 17, 4914; f) S. S. Banerjee, D.-H.
Chen, Chem. Mater. 2007, 19, 3667; V. S. Kalambur, E. K. Longmire,
J. C. Bischof, Langmuir 2007, 23, 12329; g) A. K. Gupta, M. Gupta,
Biomaterials 2005, 26, 3995; h) J. Gao, L. Li, P.-L. Ho, G. C. Mak, H.
Gu, B. Xu, Adv. Mater. 2006, 18, 3145; i) F. Hu, L. Wie, Z. Zhou, Y.
Ran, Z. Li, M. Gao, Adv. Mater. 2006, 18, 2553; j) L. M. Rossi, A. D.
Quach, Z. Rosenzweig, Anal. Bioanal. Chem. 2004, 380, 606;
k) Q. A. Pankhurst, J. Connolly, S. K. Jones, J. Phys. D 2003, 36,
R167; l) P. Tartaj, M. del Puerto Morales, S. Ventemillias-Verdaguer,
Teoc-NHACHTUNGTRENNUNG(CH2)6I (12): A mixture of 11 (0.5 g, 1.9 mmol) in CH2Cl2
(5 mL) and NEt3 (400 mL, 2.86 mmol) was cooled with an ice bath, and
methanesulfonyl chloride (200 mL, 2.57 mmol) was added slowly to the
mixture. The solution was stirred for one hour at room temperature. The
reaction medium was washed with brine and with water. The organic
layer was then dried over anhydrous Na2SO4 and solvent was removed to
afford a brown oil, which was dissolved in CH3CN (10 mL). Then NaI
(1.42 g, 9.5 mmol) was added and the reaction medium was stirred at
room temperature for 48 h. The solvent was removed and the crude
product dissolved in water (10 mL) and extracted with CH2Cl2 (4ꢂ
10 mL). Organic layers were gathered, washed with a saturated aqueous
solution of Na2S2O3, and dried over Na2SO4. Solvent was removed under
reduced pressure to give a brown oil, which was purified on a silica gel
chromatography column (petroleum ether/Et2O 70/30) to yield a color-
1
less oil (0.58 g, 82.2%). H NMR (CDCl3): d=4.61 (br, 1H, NH), 4.12 (t,
2H, CH2OCO), 3.15 (m, 4H, CH2I+CH2NH), 1.81 (q, 2H, CH2CH2I),
1.52–1.32 (m, 6H, CH2 ꢂ3), 0.95 (t, 2H, CH2Si), 0.02 ppm (s, 9H, CH3Si);
13C NMR (CDCl3): d=156.8 (s, 1C, C=O), 62.8 (s, 2C, CH2OCO), 40.8
(s, 1C, CH2NH), 33.3 (s, 1C, CH2), 30.1 (d, 2C, CH2), 25.6 (s, 1C, CH2),
17.78 (s, 1C, CH2Si), À1.43 ppm (s, 3C, CH3Si); MS (ESI): m/z (%):
calcd 394.068, found 394.068 (93) [M+Na], 765.145 (100) [2m+Na].
General procedure for the grafting of dendron 9 onto core–shell MNPs:
Carboxyl-Adembeads 300 nm nanoparticles[40] (250 mL, 2.5 mg, 0.75 mmol
CO2H), dendron 9 in DMF solution (see table below), and CHMC[41]
(12 mgmLÀ1, 200 mL, 5.66 mmol) were mixed and MeOH/Tx (1/2) was
added to adjust the reaction mixture to 1 mL (see Table 4). The reaction
flask was shaken on a rotator for 16 h at room temperature. Then parti-
cles were gathered close to the flask wall with an external magnet and
washed several times with NaOH (10 mm), Tx, and THF/Tx (2/1) solu-
tion (1 mL).
General procedure for catalytic reactions and recovery of catalysts:
Grafted MNPs (0.05–5 mg), NaOH (168 mmol), aryl boronic acid (84.37
mmol), and halo arene (56.25 mmol) were mixed in THF/Tx (1 mL, 1/9).
The mixture was stirred at 30–658C. Then grafted MNPs were separated
from the mixture by attraction with an external magnet and washed with
T. Gonzꢄlez-CarreÇo, C. J. Serna, J. Phys.
D 2003, 36, R182;
m) C. C. Berry, A. S. G. Curtis, Phys. D 2003, 36, R198.
[8] a) J. Liu, X. Peng, W. Sun, Y. Zhao, C. Xia, Org. Lett. 2008, 10,
3933; b) B. Baruwati, D. Guin, S. V. Manorama, Org. Lett. 2007, 9,
5377; c) M. S. Kwon, I. S. Park, J. S. Jang, J. S. Lee, J. Park, Org.
Lett. 2007, 9, 3417; d) D. Guin, B. Baruwati, S. V. Manorama, Org.
Lett. 2007, 9, 1419; e) H. Yoon, S. Ko, J. Jang, Chem. Commun.
2007, 1468; f) K. Mori, S. Kanai, T. Hara, T. Mizugaki, K. Ebitani,
K. Jitsukawa, K. Kaneda, Chem. Mater. 2007, 19, 1249; g) Y. Wang,
J.-K. Lee, J. Mol. Catal. A 2007, 263, 163; h) C.-H. Jun, Y. J. Park,
Y.-R. Yeon, J.-R. Choi, W.-R. Lee, S.-J. Ko, J. Cheon, Chem.
Commun. 2006, 1619; i) Y. Zheng, P. D. Stevens, Y. Gao, J. Org.
Table 4. Grafting of dendron 9 onto MNPs.
Entry
Dendron 9 (equiv)
DMF [mL]
MeOH/Tx (1/2) [mL]
1
2
3
4
5
6
1.5 mmol, 3.5 mg (2)
3 mmol, 7 mg (4)
6 mmol, 14 mg (8)
7.5 mmol, 17.5 mg (10)
15 mmol, 35 mg (20)
18.75 mmol, 43.7 mg (25)
100
200
200
200
250
312.5
450
350
350
350
300
237.5
12642
www.chemeurj.org
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 12636 – 12643

Core–Shell Superparamagnetic Nanoparticles
FULL PAPER
Chem. 2006, 71, 537; j) Z. Wang, B. Shen, Z. Aihua, N. He, Chem.
Eng. J. 2005, 113, 27; k) J. Park, E. Kang, S. U. Son, H. M. Park,
M. K. Lee, J. Kim, K. W. Kim, H.-J. Noh, J. Hoon Park, C. J. Bae, J.-
G. Park, T. Hyeon, Adv. Mater. 2005, 17, 429; l) A.-H. Lu, W.
Schmidt, N. Matoussevitch, H. Bçnnemann, B. Spliethoff, B. Tesche,
E. Bill, W. Kiefer, F. Schꢅth, Angew. Chem. 2004, 116, 4403; Angew.
Chem. Int. Ed. 2004, 43, 4303; m) X. Teng, D. Black, N. J. Watkins,
Y. Gao, H. Yang, Nano Lett. 2003, 3, 261.
[22] a) M. T. Reetz, G. Lohmer, R. Schwickardi, Angew. Chem. 1997,
109, 1559; Angew. Chem. Int. Ed. Engl. 1997, 36, 1526; b) K. Heuzꢀ,
D. Mꢀry, D. Gauss, D. Astruc, Chem. Commun. 2003, 2274; c) K.
Heuzꢀ, D. Mꢀry, D. Gauss, J.-C. Blais, D. Astruc, Chem. Eur. J. 2004,
10, 3936; d) J. Lemo, K. Heuzꢀ, D. Astruc, Org. Lett. 2005, 7, 2253;
e) J. Lemo, K. Heuzꢀ, D. Astruc, Inorg. Chim. Acta 2006, 359, 4909.
[23] a) P. S. Doyle, J. Bibette, A. Bancaud, J. L. Viovy, Sciences 2002, 295,
2237; b) Z. Bꢇlkovꢄ, A. Castagna, G. Zanusso, A. Farinazzo, S.
Monaco, E. Damoc, M. Przybylski, M. Benes, J. Lenfeld, J.-L. Viovy,
P. G. Richetti, Proteomics 2005, 5, 639; c) N. Minc, C. Fꢅtterer, K. D.
Dorfman, A. Bancaud, C. Gosse, C. Goubault, J.-L. Viovy, Anal.
Chem. 2004, 76, 3770.
[24] See general procedure for catalytic reactions and recovery of cata-
lysts with 5 mg of grafted MNPs, iodobenzene, and phenylboronic
acid in THF/Tx (2/1) at RT. Conversions were determined by GC
analysis.
[25] PF127: Pluronic F127 aqueous solution (0.3 wt%) obtained from
Pluronic F127 (Aldrich).
[9] a) M. Shokouhimehr, Y. Piao, J. Kim, Y. Jang, T. Hyeon, Angew.
Chem. 2007, 119, 7169; Angew. Chem. Int. Ed. 2007, 46, 7039; b) S.
Luo, X. Zheng, H. Xu, X. Mi, L. Zhang, J.-P. Cheng, Adv. Synth.
Catal. 2007, 349, 2431; c) R. Abu-Reziq, D. Wang, M. Post, H.
Alper, Adv. Synth. Catal. 2007, 349, 2145; d) M. Kawamura, K. Sato,
Chem. Commun. 2006, 4718; e) S. Ding, Y. Xing, M. Radosz, Y.
Shen, Macromolecules 2006, 39, 6399; f) N. T. S. Phan, C. W. Jones,
J. Mol. Catal. A 2006, 253, 123; g) P. D. Stevens, G. Li, J. Fan, M.
Yen, Y. Gao, Chem. Commun. 2005, 4435; h) R. De Palma, S. Pee-
ters, M. J. Van Bael, H. Van den Rul, K. Bonroy, W. Laureyn, J.
Mullens, G. Borghs, G. Maes, Chem. Mater. 2007, 19, 1821.
[10] a) A. Hu, G. T. Yee, W. Lin, J. Am. Chem. Soc. 2005, 127, 12486;
b) G. Chouhan, D. Wang, H. Alper, Chem. Commun. 2007, 4809;
c) Y. Zheng, C. Duanmu, Y. Gao, Org. Lett. 2006, 8, 3215; d) Z.
Yinghuai, S. C. Peng, A. Emi, S. Zhenshun, Monalisa, R. A. Kemp,
Adv. Synth. Catal. 2007, 349, 1917.
[11] a) L. M. Rossi, L. L. R. Vono, F. P. Silva, P. K. Kiyohara, E. L.
Duarte, J. R. Matos, Appl. Catal. A 2007, 330, 139; b) T. J. Yoon, W.
Lee, Y.-S. Oh, J.-K. Lee, New J. Chem. 2003, 27, 227; c) T. J. Yoon,
J. I. Kim, J.-K. Lee, Inorg. Chim. Acta 2003, 345, 228.
[12] a) K. M. Ho, P. Li, Langmuir 2008, 24, 1801; b) P. D. Stevens, J. Fan,
H. M. R. Gardimalla, M. Yen, Y. Gao, Org. Lett. 2005, 7, 2085.
[13] a) J. Ge, T. Huynh, Y. Hu, Y. Yin, Nano Lett. 2008, 8, 931; b) K.
Mori, Y. Kondo, S. Morimoto, H. Yamashita, Chem. Lett. 2007, 36,
1068; c) C. S. Gill, B. A. Price, C. W. Jones, J. Catal. 2007, 251, 145;
d) D. K. Yi, S. S. Lee, J. Y. Ying, Chem. Mater. 2006, 18, 2459;
e) C. ꢆ. Dꢄlaigh, S. A. Corr, Y. Gun’ko, S. J. Connon, Angew. Chem.
2007, 119, 4407; Angew. Chem. Int. Ed. 2007, 46, 4329; f) Z. Wang,
P. Xiao, B. Shen, N. He, Colloids Surf. 2006, 276, 116.
[14] a) R. A. Kleij, P. W. N. M. van Leeuwen, Eur. Patent, 0456317, 1991;
[Chem. Abstr. 1992, 116, 129870]; b) H. Brunner, J. Fꢅrst, J. Ziegler,
J. Organomet. Chem. 1993, 454, 87; c) For review, see H. Brunner, J.
Organomet. Chem. 1995, 500, 39; d) A. W. Knappen, J. C. deWilde,
P. W. N. M. van Leeuwen, P. Wijkens, D. Grove, G. van Koten,
Nature 1994, 372, 659; e) A. W. Bosman, H. M. Janssen, E. W.
Meijer, Chem. Rev. 1999, 99, 1665; f) R. Kreiter, A. W. Kleij, R. J.
Klein Gebbink, G. van Koten, Top. Curr. Chem. 2001, 217, 163;
g) J. J. Lee, W. T. Ford, J. Am. Chem. Soc. 1994, 116, 3753; h) G. R.
Newkome, C. N. Moorefield, F. Vçgtle, Dendrimers and Dendrons,
Concepts, Syntheses and Applications, Wiley-VCH, Weinheim, 2002.
[15] a) M. Kim, Y. Chen, Y. Liu, X. Peng, Adv. Mater. 2005, 17, 1429;
b) B. L. Frankamp, A. K. Boal, M. T. Tuominen, V. M. Rotello, J.
Am. Chem. Soc. 2005, 127, 9731; c) E. Strable, J. W. M. Bulte, B.
Moskowitz, K. Vivekanandan, M. Allen, T. Douglas, Chem. Mater.
2001, 13, 2201.
[26] 2-(N-Morpholino)ethanesulfonic acid (50 mm) in an aqueous solu-
tion of PF127 (see ref. [25]).
[27] HLB: hydrophilic/lipophilic balance. HLB(Pluronic F127)=22,
HLB(triton X405)=17.9.
[28] Tx: triton X405 aqueous solution (0.21%) obtained from triton
X405 (70%) purchased from Aldrich.
[29] Ten times more dilute medium. Total reaction volume was 10 mL.
[30] We used 200 mL of EDC in aqueous solution (12 mgmLÀ1
) or
200 mL of CHMC in aqueous solution (6 mgmLÀ1). Total reaction
volume was 1 mL.
[31] See general procedure for catalytic reactions and recovery of cata-
lysts with 2.5 mg of grafted MNPs, iodobenzene, and phenylboronic
acid at RT in THF/Tx (2/1). After 1.5 h, we obtained 100% conver-
sion with CHMC or EDC in the first cycle and 100% conversion
(with CHMC, in 14 h) and 98% conversion (with EDC, in 16 h) in
the second cycle.
[32] 200 mL of NHS water solution (12 mgmLÀ1).
[33] Accessible free carboxyl groups amount to 300–355 mmol per gram
of particles, determined by conductimetric measurements.
[34] Pd ICP analyses of grafted MNPs were 1.83 and 3.8%, respectively,
for 2 and 10 equivalents of 9 in the grafting reaction.
[35] N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457; A. Suzuki, J. Or-
ganomet. Chem. 2002, 653, 83; J. Hassan, M. Sevignon, C. Gozzi, E.
Schulz, M. Lemaire, Chem. Rev. 2002, 102, 1359; A. F. Littke, G. C.
Fu, Angew. Chem. 2002, 114, 4350; Angew. Chem. Int. Ed. 2002, 41,
4176.
[36] Core–shell g-Fe2O3/polymer 200 nm superparamagnetic nanoparti-
cles (Carboxyl-Adembeads 200 nm, Ademtech, France, 300 mmol
COOH per gram of particles) and core–shell g-Fe2O3/polymer
500 nm superparamagnetic nanoparticles (Carboxyl-Adembeads
500 nm, Ademtech, France, 250 mmol COOH per gram of particles).
[37] Catalytic tests were performed with 0.125 mg of grafted MNP mate-
rials according to the general procedure (see Experimental Section).
[38] For coupling of bromobenzene and phenylboronic acid with NaOH
in Tx/THF (9/1), at 658C for 4 h, with 2.5 mg of catalyst (2.4 mol%
Pd) we obtained 99 and 97% yield for 300 and 200 nm MNPs, re-
spectively.
[39] See general procedure: Grafted MNPs with 2 equiv of dendron 9
(5 mg, 1.96 mol% Pd), NaOH (168 mmol), phenylboronic acid
(84.37 mmol), and iodobenzene (56.25 mmol) were mixed in 1 mL of
Tx/THF (9/1). The mixture was stirred at 658C for 1 h. Then grafted
MNPs were separated from the mixture by an external magnet and
were washed with Tx/THF (9/1, (2ꢂ500 mL). Particles were washed
twice with Tx/THF (9/1) between each run.
[16] a) B.-F. Pan, F. Gao, L.-M. Ao, J. Magn. Magn. Mater. 2005, 293,
252; b) F. Gao, B.-F. Pan, W.-M. Zheng, L.-M. Ao, H.-C. Gu, J.
Magn. Magn. Mater. 2005, 293, 48; c) B.-F. Pan, F. Gao, H.-C. Gu, J.
Colloid Interface Sci. 2005, 284, 1.
[17] C. Duanmu, I. Saha, Y. Zhang, B. M. Goodson, Y. Gao, Chem.
Mater. 2006, 18, 5973.
[18] R. Abu-Reziq, H. Alper, D. Wang, M. L. Post, J. Am. Chem. Soc.
2006, 128, 5279.
[19] K. Heuzꢀ, D. Rosario-Amorin, S. Nlate, M. Gaboyard, A. Bouter,
R. Clꢀrac, New J. Chem. 2008, 32, 383.
[20] Y.-S. Shon, D. Choi, J. Dare, T. Dinh, Langmuir 2008, 24, 6924.
[21] Methoxyphenyl triallyl compound 1 was prepared readily on a large
scale by a recently described method: S. Nlate, L. Plault, F.-X.
Felpin, D. Astruc, Adv. Synth. Catal. 2008, 350, 1419.
[40] Suspension of Carboxyl-Adembeads 300 nm nanoparticles 1 wt%
MeOH/Tx (1:2).
[41] Solution of carbodiimide CHMC 12 mgmLÀ1 in MeOH/Tx (1:2).
Received: July 6, 2009
Published online: October 16, 2009
Chem. Eur. J. 2009, 15, 12636 – 12643
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
12643