Palladium nanoparticles in glycerol: A versatile catalytic system for C-X bond formation and hydrogenation processes

Article abstract of DOI:10.1002/adsc.201300753

Palladium nanoparticles stabilised by tris(3-sulfophenyl)phosphine trisodium salt in neat glycerol have been synthesised and fully characterised, starting from both Pd(II) and Pd(0) species. The versatility of this innovative catalytic colloidal solution has been proved by its efficient application in C-X bond formation processes (X=C, N, P, S) and C-C multiple bond hydrogenation reactions. The catalytic glycerol phase could be recycled more than ten times, preserving its activity and selectivity. The scope of each of these processes has demonstrated the power of the as-prepared catalyst, isolating the corresponding expected products in yields higher than 90%. The dual catalytic behaviour of this glycerol phase, associated to the metallic nanocatalysts used in wet medium (molecular- and surface-like behaviour), has allowed attractive applications in one-pot multi-step transformations catalysed by palladium, such as C-C coupling followed by hydrogenation, without isolation of intermediates using only one catalytic precursor. Copyright

Full text of DOI:10.1002/adsc.201300753

FULL PAPERS
DOI: 10.1002/adsc.201300753
Palladium Nanoparticles in Glycerol: AVersatile Catalytic System
À
for C X Bond Formation and Hydrogenation Processes
Faouzi Chahdoura,a Christian Pradel,a and Montserrat Gꢀmeza,*
a
Universitꢁ de Toulouse, UPS, LHFA, 118 route de Narbonne, F-31062 Toulouse Cedex 9, France and CNRS, LHFA UMR
5069, F-31062 Toulouse Cedex 9, France
Fax : (+33)-5-6155-8204; phone: (+33)-5-6155-7738; e-mail: gomez@chimie.ups-tlse.fr
Received: August 20, 2013; Revised: October 14, 2013; Published online: December 11, 2013
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201300753.
Abstract: Palladium nanoparticles stabilised by than 90%. The dual catalytic behaviour of this glyc-
tris(3-sulfophenyl)phosphine trisodium salt in neat erol phase, associated to the metallic nanocatalysts
glycerol have been synthesised and fully character- used in wet medium (molecular- and surface-like be-
ised, starting from both Pd(II) and Pd(0) species. haviour), has allowed attractive applications in one-
The versatility of this innovative catalytic colloidal pot multi-step transformations catalysed by palladi-
À
solution has been proved by its efficient application um, such as C C coupling followed by hydrogena-
À
in C X bond formation processes (X=C, N, P, S) tion, without isolation of intermediates using only
À
and C C multiple bond hydrogenation reactions. one catalytic precursor.
The catalytic glycerol phase could be recycled more
than ten times, preserving its activity and selectivity.
À
The scope of each of these processes has demonstrat- Keywords: C X bond formation; glycerol; hydroge-
ed the power of the as-prepared catalyst, isolating nation; nanoparticles; palladium; sequential pro-
the corresponding expected products in yields higher
ACHTUNGTRNEcNUNG esses
Introduction
agglomeration and leaching of molecular species.
Concerning solvents, ionic liquids have proven their
In the last three decades, metallic nanoparticles, in- ability to stabilise colloidal systems, in particular
cluding metallic oxides, have generated a huge inter- those based on imidazolium derivatives, which are the
est in the scientific community due to their size and most common molten salts used in this field.[5] Due to
electronic configuration leading to attractive proper- their controversial environmental impact, the search
ties for a large variety of fields and purposes, such as for friendly solvents is a current interest for academic
in microelectronics, materials, catalysis, etc.[1] In par- researchers and industrial partners. In this context,
ticular, metallic nanoparticles have been used for glycerol represents an innovative solvent coming from
a long time in heterogeneous catalysis, giving rise to the biomass and produced in high amounts as a waste
important industrial applications, the most relevant in the biodiesel production. Its low-cost, non-toxicity,
concerning oil refining.[2] More recently, a new facet high boiling point, negligible vapour pressure, high
has appeared, named “nanocatalysis”, combining the solubilising ability for organic and inorganic com-
colloidal catalysis (metallic nanocatalysts dispersed in pounds and low miscibility with other organic sol-
solution which are responsible of the reactivity in- vents, constitute striking properties to be applied in
duced) and catalysis on engineered nano-objects, catalysis.[6] Its hydroxy groups can trigger supramolec-
where nanoparticles accommodate ligands which can ular arrangements by hydrogen bond formation, al-
modify the pathway and selectivity of catalysed or- lowing the stabilisation of nanoparticles in this net-
ganic transformations.[3] With the aim to stabilise met- work.[7] In fact some works have been reported in the
allic nanoparticles in solution, the nature of both li- last years concerning the synthesis of MNP in glycerol
gands (specific scaffolds adapted to the coordination in basic medium, following the methodology named
at the metallic surface[4]) and solvents involved in the polyol process,[8] where the solvent acts also as reduc-
catalytic process play an important role to preserve ing agent.[9] However, according to the best of our
the nanometric species in the medium, avoiding both
3648
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3648 – 3660

Palladium Nanoparticles in Glycerol: A Versatile Catalytic System
knowledge, no synthetic protocols have been de- gands such as 1,3,5-triaza-7-phosphaadamantane. The
scribed in neat glycerol under base-free conditions.[10] formation of well-dispersed nanoparticles in glycerol
Being attracted by these features, we decided to was dependent on different parameters, such as the
synthesise palladium nanoparticles in neat glycerol nature of the metallic precursor, palladium concentra-
under low hydrogen pressure, studying the effect of tion and Pd/phosphine ratio (Supporting Information,
the presence of stabilisers. The as-prepared materials Figures S2 and S3). For both Pd(0) and Pd(II) starting
have been further applied in different Pd-catalysed materials, the dispersion of nanoparticles increased
À
À
processes, such as C C and C heteroatom bond for- with the metal concentration and for a given concen-
mation reactions and hydrogenations. Taking into ac- tration, with the increase of the ligand amount in rela-
count the dual behaviour of metallic nanoparticles, tion to Pd. Small and homogeneous (in size and
i.e., molecular and surface-like reactivity, we envis- shape) nanoparticles could be obtained starting from
aged sequential processes under “one-pot” conditions Pd
N
2ACHTUNGRTEN(NUNG cod)] (Pd-IIA), using
using a single catalyst without isolation of intermedi- a Pd/TPPTS ratio of 1/1 and a metal concentration of
ates.
M
(Supporting Information, Figure S2). As
shown in Figure 1, the TEM micrographs for Pd-IA
and Pd-IIA revealed a good dispersion of nanoparti-
cles, giving a broad size distribution, probably due to
the trend that nanoparticles show to be organised in
glycerol medium (4.1Æ1.4 nm and 3.5Æ1.3 nm for
Pd-IA and Pd-IIA, respectively). These colloidal solu-
Results and Discussion
Synthesis of Palladium Nanoparticles
We synthesised palladium nanoparticles (PdNP) using tions remained stable for more than one year
glycerol as a solvent, starting from Pd(II) and Pd(0) (checked by TEM and by their catalytic reactivity).
1
precursors {Pd
and [Pd2A
(OAc)2, [PdCl
E
(nbd)] We checked the stability of glycerol by H NMR mon-
(dba)3], where ma=maleic anhydride, nbd= itoring, in the presence of palladium acetate and
norbornadiene, dba=dibenzylidenacetone} and work- TPPTS under 3 bar of dihydrogen up to 1008C for
ing at 608C under a dihydrogen atmosphere (3 bar), 24 h; no degradation of glycerol was observed (Sup-
in the presence of TPPTS as stabiliser (Scheme 1).[11] porting Information, Figure S4).
We first tested the synthesis of PdNP in the absence
Actually, when Pd-IA nanoparticles were isolated
of any stabiliser other than the solvent. Under dihy- in the solid state by centrifugation from the glycerol
drogen pressure, only agglomerates could be observed solution and re-analysed by TEM, the particles exhib-
by TEM analysis of the glycerol solutions,[12] for both ited smaller size showing a narrower distribution
Pd(II) and Pd(0) precursors (Supporting Information, (Figure 2), than the material dispersed in glycerol.
Figure S1a). We also envisaged the role of glycerol as This fact could be due to an inter-particle organisa-
reducing agent, carrying out the reaction in the ab- tion by effects of the solvent favouring the formation
sence of dihydrogen; even though Pd(II) was reduced of small aggregates.
to Pd(0), mainly agglomerates were formed (Support-
We chose isolated Pd-IA for the full characterisa-
ing Information, Figure S1b); the addition of TPPTS tion of these as-prepared materials because Pd-IA
(see below) favoured the dispersion but mainly ag- was catalytically more active than Pd-IIA (see
glomerates were also obtained.
below). The IR spectrum of Pd-IA showed the pres-
We then decided to work under dihydrogen pres- ence of TTPTS in the isolated nanoparticles (Support-
sure and in the presence of phosphine-based ligands ing Information, Figure S5) and the powder XRD
with the aim to favour the formation of dispersed analysis evidenced the fcc structure for the Pd(0)
metallic nanoparticles.[4] Tris(3-sulfophenyl)phosphine nanoparticles synthesised, without any sign of Pd(II)
trisodium salt (TPPTS), a very well-known water- phases (Supporting Information, Figure S6). HR-
soluble phosphine, also exhibits a high solubility in TEM together with the electronic diffraction analyses
glycerol at room temperature, in contrast to other li- obtained by fast Fourier transform on isolated parti-
cles, confirmed the fcc structure for Pd-IA, in agree-
ment with the XRD results. The qualitative elemental
composition could be determined by EDX evidencing
the presence of palladium and TPPTS (signals ob-
served for palladium and lighter elements such as
phosphorus, sulfur, sodium, oxygen) (Figure 3)
With the aim to check the coordination of TPPTS
at the metallic surface, the formation of Pd-IA was
carried out on an NMR tube scale and monitored by
means of 31P NMR (Supporting Information, Fig-
Scheme 1. Synthesis of palladium nanoparticles Pd-XN in
glycerol using TPPTS as stabiliser.
ure S7). In the absence of dihydrogen, the reaction
Adv. Synth. Catal. 2013, 355, 3648 – 3660
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3649

Faouzi Chahdoura et al.
FULL PAPERS
Figure 1. TEM micrographs in glycerol and the corresponding size histograms for Pd-IA (top) and Pd-IIA (bottom) in glyc-
erol solution.
Figure 2. TEM micrograph and the corresponding size histogram for isolated Pd-IA.
between PdACHTUNGTRENNUNG(OAc)2 and TPPTS at 608C in glycerol of H2, all phosphorus signals practically disappeared
led to the formation of molecular palladium species due to the formation of PdNP.[13,14] In order to release
(signals in the range 22–35 ppm), without observing TPPTS from the surface, dodecanethiol was added to
the ligand-free resonance. After pressurising at 3 bar the mixture taking advantage of the known affinity of
3650
asc.wiley-vch.de
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3648 – 3660

Palladium Nanoparticles in Glycerol: A Versatile Catalytic System
Figure 3. HR-TEM micrograph for Pd-IA (left); the crystallographic planes spots observed by fast Fourier transform on
a single particle are inserted and EDX analysis for Pd-IA (right).
sulfur derivatives in particular for late transition Supporting Information). This catalytic evaluation led
metal surfaces.[13] Actually, TPPTS was quantitatively to identify the catalysts based on Pd-I and Pd-II, as
de-coordinated from the surface without any sign of those giving the highest activity (entries 11 and 19, re-
degradation.
spectively; Table S2, Supporting Information). We ob-
tained quantitative yield of the corresponding cross-
coupling product using Pd-IA nanoparticles with
1 mol% of total palladium load, as mentioned above
(entry 10, Table S1, Supporting Information); the cat-
alytic system was also active using 0.1 mol% Pd,
giving 80% of product after 24 h of reaction (entry 12,
Table S2, Supporting Information). It is important to
note that for Pd-I catalytic systems, the activity in-
À
C C Cross-Coupling Reactions Catalysed by PdNP
in Glycerol
Recognition of the Most Appropriate Catalytic
System
We considered the Suzuki–Miyaura cross-coupling of creases when the content of TPPTS increases from
4-bromoanisole with phenylboronic acid, using Pd-IA Pd/TPPTS ratio 1/0.2 to 1/1 (entries 9-11 for Pd-IC,
as catalyst, in order to optimise, in a first time, the re- Pd-IB and Pd-IA respectively, Table S2, Supporting
action conditions.[15,16] We evaluated the load of palla- Information). A similar trend was observed using Pd-
dium, nature of the base and temperature (Supporting II as catalytic precursors, although in this case the
Information, Table S1). In all the cases only the ex- highest efficiency was obtained for Pd-IIB (96% and
pected cross-coupling was obtained, without forma- 80% yield for Pd-IIB and Pd-IIA, respectively, en-
tion of homo-coupling, dehalogenation or deborona- tries 19 and 20, Table S2, Supporting information).
tion products. The best results were obtained using t-
From these results, we decided to apply the catalyt-
BuOK as a base at 1008C for 2 h of reaction, achiev- ic system coming from palladium acetate containing
ing quantitative yield of the expected cross-coupling TPPTS as stabiliser in a Pd/TPPTS ratio of 1/1, this
product (Supporting Information, Table S1, entry 10). means Pd-IA, in the catalytic study described
Under these optimised conditions, we analysed the below.[17]
effect of the catalytic material state on this reaction
(Supporting Information, Table S2). Catalytic materi-
als constituted by agglomerates were less active (en- Suzuki–Miyaura Cross-Couplings
tries 1–9, 21 and 22, Table S2, Supporting Informa-
tion) than those formed by dispersed and defined We studied the efficiency of Pd-IA in the formation
nanoparticles (entries 11, 12, 16-18 and 20, Table S2, of biaryls (Table 1). The presence of both electron-
Adv. Synth. Catal. 2013, 355, 3648 – 3660
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3651

Faouzi Chahdoura et al.
FULL PAPERS
À
Table 1. Csp2 Csp2 bond formation by Suzuki–Miyaura cross-
strate (entry 14, 40% conversion). However the tri-
methyl-substituted product 8b could not be obtained
even after 24 h of reaction (entry 15). 1-Naphthylbor-
onic acid gave the expected products with different
bromo substrates (1, 5 and 7; entries 16–18 respective-
ly), also favouring the formation of 1,1’-binaphthyl, 9d
(entry 20). 1-Phenylnaphthalene was obtained in
quantitative yield from 1-bromonaphthalene and phe-
nylboronic acid (entry 19, Table 1). Unfortunately no
coupling reaction using Pd-IA as catalyst.[a,b]
Entry R/x
Ar/y
Xy Yield [%][c]
1a >99
1
4-OMe/1
Ph/a
À
activation of Csp2 Cl bonds could be achieved, only
2
3
4
5
4-NH2/2
4-OH/3
4-Me/4
Ph/a
Ph/a
Ph/a
Ph/a
2a 98
3a 98
4a 95
5a 91
6a 97
the corresponding dehalogenation and deboronation
products were identified (Scheme S1 in the Support-
ing Information).
2-Me/5
6
4-NO2/6
4-CF3/7
4-OMe/1
4-NH2/2
4-OH/3
2-Me/5
4-CF3/7
4-NO2/6
4-OMe/1
2,6-Me2-C6H3/8 2-Me-C6H4/b
4-OMe/1
2-Me/5
4-CF3/7
1-Br-C10H7/9
1-Br-C10H7/9
Ph/a
We observed that the glycerol phase remains as
a black dispersion after extracting the organic prod-
ucts at the end of the reaction. In order to check the
stability of glycerol under the basic catalytic condi-
tions employed, we analysed the effect of the base on
glycerol in the presence of palladium acetate and
TPPTS (1H NMR monitoring, Supporting Informa-
tion, Figure S8). Even using a large excess of base in
relation to glycerol (t-BuOK/glycerol/Pd/TPPTS=2/1/
0.01/0.01), glycerol was unchanged after 24 h at
1008C.
We were then interested in the recycling of the cat-
alytic phase. Actually the catalytic phase giving 1-phe-
nylnaphthalene (entry 19, Table 1) was reused up to
ten times with no significant activity loss (isolated
yields in the range 97–80%; see Supporting Informa-
tion, Figure S9). Palladium ICP-MS analyses of the
isolated coupling product showed a very low metal
load, only 0.3 ppm after the first run; for the subse-
quent runs, palladium was not detected. It is impor-
tant to note that the catalytic phase could be recycled
although there was accumulation of salt after each
use; we tried different ways to eliminate the remain-
ing potassium bromide without success (using neat or-
ganic solvents or mixtures of them in order to precipi-
tate or extract the salt).
7
Ph/a
7a
>99
8
9
2-Me-C6H4/b
2-Me-C6H4/b
2-Me-C6H4/b
2-Me-C6H4/b
2-Me-C6H4/b
1b 93
2b 98
3b 96
5b 93
7b 95
10
11
12
13
14
15
16
17
18
19
20[f]
2,6-Me2-C6H3/c 6c 92
2,6-Me2-C6H3/c 1c 40[d]
8b
0
1-C10H7/d[e]
1-C10H7/d[e]
1-C10H7/d[e]
Ph/a
1d 98
5d 97
7d 91
9a >99
9d 96
1-C10H7/d[e]
[a]
Results from duplicate experiments. Reaction conditions:
1 mmol of substrate, t-BuOK/ArB(OH)2/substrate=2/
1.5/1; in glycerol (1 mL, 13.6 mmol); using Pd-IA as cata-
lytic precursor.
See the Supporting Information, Table S3 for the molec-
ular structures of the compounds involved.
Isolated yields after column chromatography.
Conversion determined by H NMR using mesitylene as
internal standard.
[b]
[c]
[d]
1
[e]
[f]
d corresponds to 1-naphthylboronic acid.
1-Bromonaphthalene (9) and d used as reagents to give
1,1’-binaphthyl (9d).
We also evaluated the catalytic behaviour of Pd-IA
donor (1–5) or electron-withdrawing (6 and 7) sub- in more challenging processes leading to the forma-
stituents on the substrate led to high isolated yields tion of Csp3 Csp2 bonds (Table 2).[20] Activated sub-
À
(>91%) of the corresponding cross-coupling product strates, such as bromomethylbenzene 10 (entries 1–5,
using phenylboronic acid (entries 1–7, Table 1). Sub- Table 2) and 3-bromo-1-propene 11 (entries 6–10,
strate 2, p-bromoaniline, featuring a free NH2 group, Table 2) easily reacted with arylboronic acids, giving
could be directly used without previous protection;[18] the corresponding cross-couplings in high yields (>
no Buchwald–Hartwig amination was observed.[19] It 91%; entries 1–10, Table 2), including sterically de-
is important to note that products containing hydroxy manding reagents such as 2,6-dimethylphenylboronic
and amino groups (2a and 3a, entries 2 and 3) could acid c (entries 3 and 8, Table 2) and electron-rich bor-
be also efficiently extracted from the catalytic phase onic acids such as 4-methoxyphenylboronic acid e (en-
(using pentane or dichloromethane as solvents, which tries 5 and 10, Table 2). Chloro-based substrates 12
are immiscible with glycerol). Using 2-methylphenyl- and 13 were also activated by Pd-IA, giving 91% of
boronic acid (entries 8–12) and 2,6-dimethylphenyl- yield of the corresponding cross-coupling products,
boronic acid (entry 13), cross-coupling products were 12a and 13b, respectively, but at longer reaction times
isolated in high yields, even for the formation of (2,2’- (12 h) (entries 11 and 12, Table 2). Unfortunately no
dimethyl)-1,1’-biphenyl 5b (entry 11); a lower activity coupling product was obtained using bromocyclohex-
was observed using 4-methoxybromobenzene as sub- ane and phenylboronic acid as reagents, even after
3652
asc.wiley-vch.de
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3648 – 3660

Palladium Nanoparticles in Glycerol: A Versatile Catalytic System
À
Table 2. Csp3 Csp2 bond formation by Suzuki–Miyaura cross-
Table 3. Pd-catalysed Heck–Mizoroki coupling reactions
using Pd-IA as catalyst.[a,b]
coupling reaction using Pd-IA as catalyst.[a,b]
Entry R,X/x
Ar-CH=CH2
Product Yield
[%][c]
Entry
R
ArB(OH)2
Product Yield [%][c]
1
2
3
4
5
6
7
8
9
4-OMe, I/14 f (Ar=Ph)
14f
15f
16f
17f
14g
98
92
96
91
95
90
85
80
81
2-OH, I/15
2-NH2, I/16
2-CH3, I/17
4-OMe, I/14
4-OMe, I/14
f (Ar=Ph)
f (Ar=Ph)
f (Ar=Ph)
1
2
3
4
5
6
7
8
10 a (Ar=Ph)
10 b (Ar=2-Me-C6H4)
10 c (Ar=2,6-Me2-C6H3) 10c
10 d (Ar=1-C10H7) 10d
10 e (Ar=4-MeO-C6H4) 10e
11 a (Ar=Ph)
11 b (Ar=2-Me-C6H4)
11 c (Ar=2,6-Me2-C6H3) 11c
11 d (Ar=1-C10H7) 11d
11 e (Ar=4-MeO-C6H4) 11e
12 a (Ar=Ph)
13 a (Ar=Ph)
10a
10b
>99
92
93
g
[d] (Ar=4-py)
97
91
h
[e] (Ar=2-C10H7) 14h
4-OMe, Br/1 f (Ar=Ph)
1f
3f
5 f
11a
11b
98
95
4-OH, Br/3
2-Me, Br/5
f (Ar=Ph)
f (Ar=Ph)
99
92
[a]
9
Results from duplicate experiments. Reaction conditions:
1 mmol of substrate, t-BuOK/Ar-CH=CH2/substrate=2/
1.5/1; in glycerol (1 mL); using Pd-IA as catalytic precur-
sor.
See the Supporting Information, Table S5 for the molec-
ular structures of the compounds involved.
Isolated yields after column chromatography.
4-Vinylpyridine.
10
11[d]
12[d]
>99
93
95
12a
13a
[b]
[a]
Results from duplicate experiments. Reaction conditions:
1 mmol of substrate, t-BuOK/ArB(OH)2/substrate=2/
1.5/1; in glycerol (1 mL, 13.6 mmol); using Pd-IA as cata-
lytic precursor.
See the Supporting Information, Table S4 for the molec-
ular structures of the compounds involved.
Isolated yields after column chromatography.
Reaction time: 12 h.
[c]
[d]
[e]
2-Vinylnaphthalene.
[b]
[c]
[d]
Sonogashira Cross-Couplings
Pd-IA was tested as catalytic precursor in Cu-free So-
24 h of reaction; only benzene was detected coming nogashira cross-coupling reactions (Table 4; see the
from the deboronation process.
Supporting Information, Table S6 for conditions opti-
misation).[22] The catalyst was active and chemoselec-
tive for the reaction between iodoaryl substrates (14,
Heck–Mizoroki Cross-Couplings
Pd-IA was also an active catalyst for Heck–Mizoroki Table 4. Pd-catalysed Sonogashira coupling reactions using
Pd-IA as catalyst.[a,b]
coupling reactions (Table 3).[15,21] Under the same re-
action conditions as used for the Suzuki–Miyaura
cross-couplings, styrene (f), 4-vinylpyridine (g) and 2-
vinylnaphthalene (h) coupled with several iodo-based
substrates, giving the expected coupling products in
high yields (in the range of 90–98%). In particular,
the most hindered 1,2-disubstituted products 15f–17f
could be efficiently formed, including those contain-
ing protic substituents such as NH2 and OH groups
(entries 2-4, Table 3). Bromo substrates, i.e., 4-meth-
Entry
R,R’/x
Product
Yield [%][c]
1
2
3
4
5
H, OMe/14
H, NO2/20
H, Br/21
CN, H/22
Me, NO2/23
14i
20i
21i
22i
23i
98
91
91
98
91
ACHTUNGTRENNUNGoxy- (1), 4-hydroxy- (3) and 2-methylbromobenzene
(5), reacted with styrene to afford the corresponding
coupling products in good yields (entries 7–9,
Table 3). However, the reaction between 4-chloroace-
tophenone and styrene was unsuccessful after 24 h of
reaction, giving less than 5% of the desired product.
[a]
Results from duplicate experiments. Reaction conditions:
ꢀ
1 mmol of substrate, t-BuOK/Ph-C CH/substrate=2/1.5/
1; in glycerol (1 mL); using Pd-IA as catalytic precursor.
See the Supporting Information, Table S7 for the molec-
ular structures of the compounds involved.
[b]
[c]
Isolated yields after column chromatography.
Adv. Synth. Catal. 2013, 355, 3648 – 3660
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3653

Faouzi Chahdoura et al.
FULL PAPERS
À
Figure 5. Pd-catalysed C N bond formation by direct reac-
tion of acrylonitrile and morpholine. Diagram showing the
recycling of the catalytic phase. Figures indicate the isolated
yield of 28o after each recycling.
Figure 4. Scope of the Sonogashira reaction catalysed by Pd-
IA (figures correspond to isolated yields).
(Figure 5). The catalytic phase could be recycled up
to ten times without significant activity loss. TEM
20–23) and phenylacetylene, giving high yields (in the analysis after five runs showed well-dispersed nano-
range 91–98%) for substrates containing both elec- particles with a mean diameter 3.0Æ1.3 nm (Support-
tron-donor and electron-withdrawing groups, includ- ing Information, Figure S10), rather smaller than the
ing sterically demanding 2-substituted-iodoaryl com- starting material (Figure 1). This trend could be relat-
pounds (22 and 23). However, the reaction between ed to a better dispersion of the nanoparticles upon
4-nitrobromobenzene and phenylacetylene gave less several catalytic runs, partially disrupting inter-parti-
than 10% of the expected cross-coupling product.
cle rearrangements which are favoured by the hydro-
This catalytic system was compatible with alcohol gen bonds of the solvent, analogously to that ob-
and amino functions, leading selectively to a variety served after isolation of palladium nanoparticles from
of compounds containing polar substituents, using as the glycerol phase (see above, Figure 2).
reagents functionalised iodoaryl substrates and termi-
In contrast to the cross-coupling reactions described
nal alkynes (Figure 4 and Supporting Information, above, no base is required and in consequence the ex-
Table S7), giving yields higher than 88% including for traction of the organic products is easier to handle.
those coming from 2-substituted-iodobenzene sub-
strates 25–27.
We also used technical grade glycerol (85%), in-
stead of pure glycerol (99.5%), for the preparation of
the colloidal palladium system; actually we could ob-
serve the same catalytic behaviour in terms of yield of
the expected product and recyclability of the catalytic
phase (Supporting Information, Scheme S2).
À
À
À
PdNP in Glycerol Catalysed C N, C S and C P
Bond Formation by C H Bond Activation
À
The reaction scope involving primary and secon-
Encouraged by the versatility, chemoselectivity and dary amines, thiols and secondary phosphines such as
À
activity of the Pd-IA catalytic phase in glycerol in C
C bond formation processes by cross-coupling reac- itacon
diphenylphosphine, including the use of diethyl
A
À
tions, we decided to investigate the formation of C
heteroatom bond formation, such as C N and C S tion, Table S9). Secondary (28p–28r) and tertiary
strates, is shown in Figure 6 (see Supporting Informa-
À
À
[23]
À
bonds, by C H bond activation. We chose the base- (28o, 28s, 28t, 29o, 29u) amines could be obtained in
free intermolecular reaction between acrylonitrile and yields higher than 90%. Mono- and bis-thioethers
morpholine to optimise the conditions (Supporting In- were also efficiently isolated (28u–28x). It is impor-
formation, Table S8). The catalytic system was active tant to note that this methodology represents a con-
even at low palladium load (0.1 mol% Pd, 50% con- venient way to prepare tertiary phosphines in relation
À
version at 808C after 12 h of reaction); a quantitative to the commonly used additions of P H moieties into
yield of the expected product was obtained at 1008C alkenes.[24] Unfortunately, tests aimed at C O bond
À
[25]
À
after 2 h of reaction using 1 mol% of palladium formation by C H activation were unsuccessful.
3654
asc.wiley-vch.de
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3648 – 3660

Palladium Nanoparticles in Glycerol: A Versatile Catalytic System
Applications in One-Pot Sequential Processes
À
After proving the efficiency of the GlyPC in C X
bond formation and C C multiple bond hydrogena-
À
tion reactions, we decided to use Pd-IA in one-pot se-
quential processes, such as C C cross-coupling reac-
À
tions followed by hydrogenation, taking advantage of
the dual catalytic reactivity exhibited by metallic
nanoparticles dispersed in a liquid phase, i.e., their
molecular (homogeneous) and surface (heterogene-
ous) like behaviour,[26] according to what we had pre-
viously observed in ionic liquid media.[11a,b]
Actually Pd-IA gave the expected products in high
global yields (>92%) by a two-step process without
isolation of the intermediate products (Scheme 2a–c).
It is important to note that the presence of nitro
groups leads to the corresponding saturated amine
product (6cH, 20iH).
With the aim to obtain a target product of industri-
al interest, we envisaged preparing the molecule 47H
showing aromatic properties (raspberry scent),[11b] by
a one-pot Heck–Mizoroki/hydrogenation sequential
process (Scheme 2d); it was isolated in 95% global
yield. This methodology permits us to isolate the de-
sired product using one palladium catalyst in contrast
to the industrial procedure employing both a homoge-
À
À
À
Figure 6. Scope of the C N, C S and C P couplings cata-
lysed by Pd-IA (figures correspond to isolated yields).
PdNP in Glycerol Catalysed C=C Hydrogenation
Reactions
As expected by the surface-like catalytic behaviour of neous ([PdACHTNURTGNEUNG(PPh3)4]) for the Heck coupling and a heter-
the palladium nanoparticles,[4c,11a,b,15] we tested Pd-IA ogeneous (Pd/C) one for the hydrogenation step,
À
as catalyst for the hydrogenation of unsaturated C C avoiding the separation of the intermediate corre-
bonds (Table 5). The catalyst was efficient for the re- sponding to the cross-coupling product.[27]
duction of mono-substituted HC=CH2 (30 and 31), di-
gem-substituted C=CH2 (32–34), and (E)- (35–38) and
(Z)-1,2-disubstituted HC=CH (39–41) substrates, in-
cluding the quantitative hydrogenation of the endocy-
clic C=C bond of the coumarin lactone (41). 1,2-Di-
ACHTUNGTRENNUNGsubstituted alkynes and nitro functions could also be
À
hydrogenated, giving the corresponding saturated C
C (44H and 45H) and amino NH2 (46H) derivatives,
respectively. However the indole 42 and furan 43
could not be hydrogenated, even under harsher condi-
tions (5 mol% of catalyst, 20 bar H2, 1008C, 24 h).
The hydrogenation process of (E)-4-phenylbut-3-en-2-
one (37), giving the saturated compound 37H, skele-
ton present in several fragrances, could be recycled
more than ten times without activity loss (Supporting
Information, Figure S11). TEM analysis after five
runs showed relative small and spherical nanoparti-
cles with a mean diameter 3.8Æ1.3 nm, closer to that
observed for the starting catalytic material, exhibiting
good dispersion together with inter-particle associa-
tions (Figure 7), most likely due to the nature of the
solvent.
À
Scheme 2. One-pot C C cross-coupling/hydrogenation se-
quential processes catalysed by Pd-IA.
Adv. Synth. Catal. 2013, 355, 3648 – 3660
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3655

Faouzi Chahdoura et al.
FULL PAPERS
ꢀ
Table 5. Pd-catalysed hydrogenation reactions of C=C and C C bonds using Pd-IA as cat-
alyst.[a,b]
[a]
Results from duplicate experiments. Reaction conditions: 1 mmol of substrate, 1 mL
glycerol, using Pd-IA as catalytic precursor.
Isolated yields.
Substrate 37 was used to optimise the reaction conditions; see the Supporting Informa-
[b]
[c]
tion, Table S10.
Conclusions
nanoparticles dispersed in glycerol were efficiently
used in C C and C X bond formation processes and
À
À
In conclusion, for the first time we could synthesise hydrogenations. This catalytic system could be recy-
PdNP in glycerol in the presence of TPPTS acting as cled more than ten times without loss of activity or
stabiliser; both the phosphane and the dihydrogen loss of selectivity; the palladium present in the isolat-
used as reducing agent were proven necessary to ed organic products was often undetectable by ICP-
attain small and well-dispersed nanoparticles. Optimi- MS analysis. In addition, the dual homogeneous and
sation of several parameters (such as temperature, heterogeneous catalytic behaviour of palladium nano-
concentration, both nature of stabiliser and metallic particles dispersed in glycerol could be demonstrated
precursor) led us to identify an appropriate colloidal by the Heck–Mizoroki coupling/hydrogenation se-
system to be used in “wet” catalysis, Pd-IA which re- quential process to obtain target molecules, such as
mained unchanged for more than one year. These that responsible for the raspberry fragrance.
3656
asc.wiley-vch.de
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3648 – 3660

Palladium Nanoparticles in Glycerol: A Versatile Catalytic System
Figure 7. TEM micrographs of Pd-IA in glycerol with their corresponding size distributions: before catalytic use (top) and
after five runs (bottom) for the hydrogenation of (E)-4-phenylbut-3-en-2-one.
a Perkin–Elmer Spectrum One FT-IR. Mass chromatograms
were carried out by the “Service commun de spectromꢁtrie
de masse” of the “Institute de Chimie de Toulouse de l’Uni-
versitꢁ Paul Sabatier”. Electronic impact (EI) and chemical
ionisation (CI using methane or ammonia as reactant gas),
on a TSQ 7000 Thermo Electron apparatus and electrospray
(ES) on an API-365 MS/MS spectrometer (Perkin–Elmer
Sciex). Gas chromatography analyses were performed with
a Perkin–Elmer Clarus 500 chromatograph fitted with an
FID and MS detector, using dodecane as internal standard.
The column employed was SGE BPX5 (30 mꢃ0.32 mmꢃ
0.25 mm) phase composed by 5% of phenyl methylsiloxane.
The injector temperature was 2508C and the flow
2 mLminÀ1. Temperature programme: 408C for 2 min;
108CminÀ1 to 3008C hold for 5 min. TEM images of parti-
cles dispersed in glycerol and in the solid state were ob-
tained from transmission electron microscopes JEOL JEM
1400 running at 120 kV and JEOL JEM 2100F running at
200 kV equipped with X PGT analyser (detection of light el-
ements, resolution 135 eV), at the “Service Commun de Mi-
croscopie Electronique de l’Universitꢁ Paul Sabatier,
TEMSCAN’’. A drop of solution was deposited on a holey
carbon grid and the excess of glycerol was removed in order
to obtain a film as thin as possible. The nanoparticles size
Studies concerning the applications of these types
of colloidal catalytic systems in the synthesis of com-
pounds exhibiting interest in fine chemistry, such as
those containing heterocycles are currently underway.
Experimental Section
General
All preparations and manipulations were performed using
standard Schlenk techniques under an argon atmosphere.
Unless stated otherwise, commercially available compounds
were used without further purification. Glycerol was
treated under vacuum at 808C overnight prior to use.
[Pd(ma)ACHTUNGTRENNUNG
(nbd)][28] was prepared according to previously de-
scribed procedures. NMR spectra were recorded on
a Bruker Avance 300 spectrometer at 293 K (299.7 MHz for
1H NMR, 75.5 MHz for 13C NMR and 121 MHz for
31P NMR). GC analyses were carried out on an Agilent
GC6890 with a flame ionisation detector, using a SGE
BPX5 column composed by 5% of phenylmethylsiloxane.
IR spectra were recorded in the range of 4000–400 cmÀ1 on
Adv. Synth. Catal. 2013, 355, 3648 – 3660
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3657

Faouzi Chahdoura et al.
FULL PAPERS
distribution and average diameter were directly determined
from TEM images by Image-J software associated to a Mi-
crosoft Excel macro developed by Christian Pradel. The
powder X-ray diffraction patterns were collected on a XPert
Pro (Theta-Theta mode) Panalytical diffractometer with
a(Cu Ka1, Ka2)=1.54059, 1.54439 ꢄ.
products were previously reported, and identified by com-
1
parison of their H and 13C NMR spectra and GC-MS data
with those of authentic samples.
À
General Procedure for Pd-Catalysed Sonogashira C
C Cross-Couplings in Glycerol
Aryl halide (1 mmol), the corresponding terminal alkyne
(1.2 mmol), t-BuOK (2.1 mmol) were consecutively added
to 1 mL of a solution of preformed nanoparticles in glycerol.
The resulting mixture was heated at 1008C during 2 h and
then cooled to room temperature. The organic products
were extracted from the catalytic mixture with dichlorome-
thane (3ꢃ10 mL) and the combined organic phases were
dried over anhydrous Na2SO4, filtered and the solvent
evaporated under reduced pressure. The product was puri-
fied by short-column chromatography on silica gel. All the
products were previously reported, and identified by com-
Synthesis of Palladium Nanoparticles in Solution
0.05 mmol of palladium precursor {14.1 mg for [PdCl
11.2 mg for Pd(OAc)2; 14.8 mg [Pd(ma)(nbd)]; 22.8 mg for
[Pd2A(dba)3]} and 0.01 to 0.05 mmol of ligand TPPTS
2ACHTUNGTRNE(NUNG cod)];
A
ACHTUNGTRENNUNG
CHTUNGTRENNUNG
(5.68 mg to 28.4 mg) were dissolved in 5 mL of glycerol and
stirred at room temperature under argon in a Fischer–Porter
bottle until complete dissolution. The system was then pres-
surised with 3 bar of dihydrogen and stirred at 808C over-
night, leading to a black solution. After releasing the residu-
al gas, the solution was washed with pentane (2ꢃ5 mL) and
dried under reduced pressure for 1 h.
1
parison of their H and 13C NMR spectra and GC-MS data
with those of authentic samples.
Isolation of Palladium Nanoparticles Pd-IA from the
Glycerol Solution
À
General Procedure for Pd-Catalysed C X (X=N, S)
Bond Formation in Glycerol
0.05 mmol (11.2 mg) of PdACTHNUTRGNE(UNG OAc)2 and 0.05 mmol (28.4 mg)
of ligand TPPTS were dissolved in 5 mL of glycerol and
stirred at room temperature under argon in a Fischer–Porter
bottle until complete dissolution. The system was pressur-
ised under 3 bar of dihydrogen and stirred at 808C over-
night. The mixture was then cooled at room temperature,
transferred to an appropriate container for centrifugation at
1000 rpm for 24 h. Palladium nanoparticles in the solid state
were then separated by decantation. Yield: 35%.
Alkene substrate (1 mmol) and the corresponding amine or
thiol (1.2 mmol) were consecutively added to 1 mL of a solu-
tion of preformed nanoparticles in glycerol. The resulting
mixture was heated at 1008C during 2 h and then cooled to
room temperature. The organic products were extracted
from the catalytic mixture with dichloromethane (3ꢃ10 mL)
and the combined organic phases were dried over anhydrous
Na2SO4, filtered and the solvent evaporated under reduced
pressure. The product was purified by short-column chroma-
tography on silica gel. All the products were previously re-
ported, and identified by comparison of their 1H and
13C NMR spectra and GC-MS data with those of authentic
samples.
General Procedure for Pd-Catalysed Suzuki–Miyaura
À
C C Cross-Couplings in Glycerol
Aryl or benzyl or allyl halide (1 mmol), the corresponding
arylboronic acid (1.2 mmol) and t-BuOK (2.1 mmol) were
consecutively added to 1 mL of a solution of preformed
nanoparticles in glycerol. The resulting mixture was heated
at 1008C during 2 h and then cooled to room temperature.
The organic products were extracted from the catalytic mix-
ture with dichloromethane (3ꢃ10 mL) and the combined or-
ganic phases were dried over anhydrous Na2SO4, filtered
and the solvent evaporated under reduced pressure. The
product was purified by short-column chromatography on
silica gel. All the products were previously reported, and
General Procedure for Pd-Catalysed Hydrogenation
in Glycerol
Alkene (1 mmol) was added added to 0.1 mL of a solution
of preformed nanoparticles in glycerol. The resulting mix-
ture was stirred at room temperature under argon in
a Fisher-Porter bottle. The system was then pressurised with
dihydrogen (up to 3 bar) and stirred at 1008C for 2 h. The
mixture was then the cooled to room temperature. The cata-
lytic mixture was extracted with dichloromethane (3ꢃ
10 mL) and the combined organic phases were dried over
anhydrous Na2SO4, filtered and the solvent evaporated
under reduced pressure. The product was purified by short-
column chromatography on silica gel. All the products were
previously reported, and identified by comparison of their
1H and 13C NMR spectra and GC-MS data with those of au-
thentic samples.
1
identified by comparison of their H and 13C NMR spectra
and GC-MS data with those of authentic samples.
General Procedure for Pd-Catalysed Heck–Mizoroki
À
C C Cross-Couplings in Glycerol
Aryl halide (1 mmol), the corresponding vinyl substrate
(1.2 mmol) and t-BuOK (2.1 mmol) were consecutively
added to 1 mL of a solution of preformed nanoparticles in
glycerol. The resulting mixture was heated at 1008C during
2 h and then cooled to room temperature. The organic prod-
ucts were extracted from the catalytic mixture with dichloro-
methane (3ꢃ10 mL) and the combined organic phases were
dried over anhydrous Na2SO4, filtered and the solvent
evaporated under reduced pressure. The product was puri-
fied by short-column chromatography on silica gel. All the
General Procedure for Recycling the Catalytic Phase
A typical experimental procedure to recycle the catalytic
phase is described. The glycerol phase from the previous
run was maintained for 30 min under dynamic vacuum while
stirring at 1008C. Then, the corresponding reagents were
added to the glycerol phase. The catalytic mixture was then
3658
asc.wiley-vch.de
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3648 – 3660

Palladium Nanoparticles in Glycerol: A Versatile Catalytic System
treated under the corresponding conditions applied for the
first run, the final product was extracted with dichlorome-
thane and analysed by GC and NMR.
B. Lastra-Barreira, P. Crochet, V. Cadierno, Chem.
Commun. 2011, 47, 6208–6227.
[7] In this context, it is important to underline the effect of
alcohols and amines in the stabilization of metallic
nanoparticles in non-protic solvents. For selected con-
tributions, see: a) I. Favier, E. Teuma, M. Gꢀmez, C. R.
Chim. 2009, 12, 533–545, and references cited therein;
b) E. Ramꢆrez, L. Eradꢇs, K. Philippot, P. Lecante, B.
Chaudret, Adv. Funct. Mater. 2007, 17, 2219–2228; c) C.
Pan, K. Pelzer, K. Philippot, B. Chaudret, F. Dassenoy,
P. Lecante, M.-J. Casanove, J. Am. Chem. Soc. 2001,
123, 7584–7593.
Acknowledgements
Financial support from the Centre National de la Recherche
Scientifique (CNRS) and the Universitꢀ Paul Sabatier are
gratefully acknowledged. F. C. thanks the CNRS and Rꢀgion
Midi-Pyrꢀnꢀes for a PhD grant.
[8] a) K. J. Carroll, J. U. Reveles, M. D. Shultz, S. N.
Khanna, E. E. Carpenter, J. Phys. Chem. C 2011, 115,
2656–2664; b) M. Delample, N. Villandier, J.-P. Douliez,
S. Camy, J.-S. Condoret, Y. Pouilloux, J. Barrault, F.
Jꢁrꢅme, Green Chem. 2010, 12, 804–808.
[9] For a selected review, see: A. E. Dꢆaz-Alvarez, V. Ca-
dierno, Appl. Sci. 2013, 3, 55–69, and references cited
therein.
[10] F. Jꢁrꢅme and co-workers have applied preformed
PdNP stabilised by an aminopolysaccharide and pre-
pared in an organic solvent as catalytic precursor for
b,b-diarylation reactions: a) A. Karam, N. Villandier,
M. Delample, C. Klein Koerkamp, J.-P. Douliez, R.
Granet, P. Krausz, J. Barrault, F. Jꢁrꢅme, Chem. Eur. J.
2008, 14, 10196–10200; b) M. Delample, N. Villandier,
J.-P. Douliez, S. Camy, J.-S. Condoret, Y. Pouilloux, J.
Barrault, F. Jꢁrꢅme, Green Chem. 2010, 12, 804–808.
[11] For some representative contributions on the synthesis
of metallic nanoparticles starting from organometallic
precursors, see: a) L. Rodriguez-Pꢁrez, C. Pradel, P.
Serp, M. Gꢀmez, E. Teuma, ChemCatChem 2011, 3,
749–754; b) S. Jansat, J. Durand, I. Favier, F. Malbosc,
C. Pradel, E. Teuma, M. Gꢀmez, ChemCatChem 2009,
1, 244–246; c) K. Philippot, B. Chaudret, C. R. Chim.
2003, 6, 565–572.
References
[1] For selected contributions, see: a) C. J. Murphy, A. M.
Gole, S. E. Hunyadi, J. W. Stone, P. N. Sisco, A. Alkila-
ny, B. E. Kinard, P. Hankins, Chem. Commun. 2008,
544–557; b) Nanoparticles. From theory to application,
(Ed.: G. Schmid), Wiley-VCH, Weinheim, 2004;
c) Metal nanoparticles: synthesis, characterization and
applications, (Eds.: D. L. Feldheim, C. A. Foss Jr),
Marcel Dekker, New York, 2002.
[2] a) A. T. Bell, Science 2003, 299, 1688–1691; b) Nano-
structured catalysts, (Eds.: S. L. Scott, C. M. Crudden,
C. W. Jones), Kluwer Academics/Plenum Publishers,
New York, 2003; c) Nanotechnology in catalysis, (Eds.:
B. Zhou, S. Hermans, G. Somorjai), Kluwer Academics/
Plenum Publishers, New York, 2004.
[3] a) Nanocatalysis, (Eds.: U. Heiz, U. Landman), Spring-
er-Verlag, Berlin, 2007; b) Nanoparticles in catalysis,
(Ed.: D. Astruc), Wiley-VCH, Weinheim, 2008;
c) Nanomaterials in catalysis, (Eds.: K. Philippot, P.
Serp), Wiley-VCH, Weinheim, 2013; d) K. An, S.
Alayoglu, T. Ewers, G. A. Somorjai, J. Colloid Interface
Sci. 2012, 373, 1–13.
[12] The negligible vapour pressure of glycerol (<1 mmHg
at 508C) permits the TEM analyses (technique working
under vacuum conditions) of the glycerol solutions
without isolating the nanoparticles in the solid state.
For physico-chemical properties of glycerol, see: M.
Plagiaro, M. Rossi, in: The future of glycerol: new
usages for a versatile raw material, RSC Publsihing,
Cambridge, 2008.
[13] I. Favier, S. Massou, E. Teuma, K. Philippot, B. Chau-
dret, M. Gꢀmez, Chem. Commun. 2008, 3296–3298.
[14] O. Kohlmann, W. E. Steinmetz, X.-A. Mao, W. P.
Wuelfing, A. C. Templeton, R. W. Murray, C. S. John-
son Jr, J. Phys. Chem. B 2001, 105, 8801–8809.
[15] For a recent review concerning the applications of pal-
ladium nanoparticles in organic synthesis, see: I. Favier,
D. Madec, E. Teuma, M. Gꢀmez, Curr. Org. Chem.
2011, 15, 3127–3174, and references cited therein.
[16] For the use of preformed PdNP in Suzuki–Miyaura and
Heck–Mizoroki reactions, see the following reviews:
a) A. Balanta, C. Godard, C. Claver, Chem. Soc. Rev.
2011, 40, 4973–4985; b) C. Burda, X. Chen, R. Nar-
ayanan, M. A. El-Sayed, Chem. Rev. 2005, 105, 1025–
1102.
[4] a) S. Jansat, M. Gꢀmez, K. Philippot, G. Muller, E.
Guiu, C. Claver, S. Castillꢀn, B. Chaudret, J. Am.
Chem. Soc. 2004, 126, 1592–1593; b) I. Favier, M.
Gꢀmez, G. Muller, R. Axet, S. Castillꢀn, C. Claver, S.
Jansat, K. Philippot, B. Chaudret, Adv. Synth. Catal.
2007, 349, 2459–2469; c) J. Durand, E. Teuma, M.
Gꢀmez, Eur. J. Inorg. Chem. 2008, 3577–3586; d) I.
Favier, P. Lavedan, S. Massou, E. Teuma, K. Philippot,
B. Chaudret, M. Gꢀmez, Top. Catal. 2013, 56, 1253–
1261.
[5] a) I. Favier, D. Madec, M. Gꢀmez, in: Metallic nanopar-
ticles in ionic liquids. Applications in catalysis, chapter 5
in: Nanomaterials in catalysis, (Eds.: K. Philippot, P.
Serp), Wiley-VCH, Weinheim, 2013, pp 203–249; b) J.
Dupont, J. D. Scholten, Chem. Soc. Rev. 2010, 39, 1780–
1804; c) H. Olivier-Bourbigou, L. Magna, D. Morvan,
Appl. Catal. A 2010, 373, 1–56; d) M. Antonietti, D.
Kuang, B. Smarsly, Y. Zhou, Angew. Chem. 2004, 116,
5096–5100; Angew. Chem. Int. Ed. 2004, 43, 4988–4992.
[6] For selected reviews, see: a) A. Corma, S. Iborra, A.
Velty, Chem. Rev. 2007, 107, 2411–2502; b) A. Wolfson,
C. Dlugy, Y. Shotland, Environ. Chem. Lett. 2007, 5,
67–71; c) Y. Zheng, X. Chen, Y. Shen, Chem. Rev. 2008,
108, 5253–5277; d) Y. Gu, F. Jꢁrꢅme, Green Chem.
2010, 12, 1127–1138; e) A. E. Dꢆaz-Alvarez, J. Francos,
[17] For a recent contribution of Pd-catalysed Sukuki-
Miyaura complexes in glycerol, see: A. Azua, J. A.
Adv. Synth. Catal. 2013, 355, 3648 – 3660
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3659

Faouzi Chahdoura et al.
FULL PAPERS
Mata, P. Heymes, E. Peris, F. Lamaty, J. Martinez, E.
Colacino, Adv. Synth. Catal. 2013, 355, 1107–1116.
[18] For selected contributions, see: a) S. Caron, S. S. Mas-
sett, D. E. Bogle, M. J. Castaldi, T. F. Braish, Org. Pro-
cess Res. Dev. 2001, 5, 254–256; b) C. A. Fleckenstein,
H. Plenio, Chem. Eur. J. 2008, 14, 4267–4279.
[19] For selected reviews, see: a) J. F. Hartwig, Acc. Chem.
Res. 2008, 41, 1534–1544; b) D. S. Surry, S. Buchwald,
Angew. Chem. 2008, 120, 6438–6461; Angew. Chem. Int.
Ed. 2008, 47, 6338–6361; c) C. A. Busacca, D. R. Fan-
drick, J. J. Song, C. H. Senanayake, Adv. Synth. Catal.
2011, 353, 1825–1864.
[20] a) For a pioneering work, see: J. H. Kirchhoff, C. Dai,
G. C. Fu, Angew. Chem. 2002, 114, 2025–2027; Angew.
Chem. Int. Ed. 2002, 41, 1945–1947; b) C. Valente, S.
Baglione, D. Candito, C. J. OꢈBrien, M. G. Organ,
Chem. Commun. 2008, 735–737; c) C. Mollar, M.
Besora, F. Maseras, G. Asensio, M. Medio-Simon,
Chem. Eur. J. 2010, 16, 13390–13397.
[21] For a recent contribution, see: A. L. Isfahani, I. Mo-
hammadpoor-Baltork, V. Mirkhani, A. R. Khosropour,
M. Moghadam, S. Tangestaninejad, R. Kia, Adv. Synth.
Catal. 2013, 355, 957–972.
[22] For relevant contributions of PdNP as catalytic precur-
sors for Sonogashira couplings, see: a) N. Kim, M. S.
Kwon, C. M. Park, J. Park, Tetrahedron Lett. 2004, 45,
7057–7059; b) P. Li, L. Wang, H. Li, Tetrahedron 2005,
61, 8633–8640. For a selected review concerning the
synthesis of acetylenes, see: c) R. Chinchilla, C. Nꢉjera,
Chem. Rev. 2007, 107, 874–922.
[23] For recent reviews, see: a) T. W. Lyons, M. S. Sanford,
Chem. Rev. 2010, 110, 1147–1169; b) J. Wencel-Delord,
T. Drçge, F. Liu, F. Glorius, Chem. Soc. Rev. 2011, 40,
4740–4761.
[24] For a representative contribution, see: M. V. Jimꢁnez,
J. J. Pꢁrez-Torrente, M. I. Bartolomꢁ, L. A. Oro, Syn-
thesis 2009, 1916–1922.
[25] The reaction of phenol or tert-butyl alcohol with acrylo-
nitrile did not proceed during 24 h of reaction under
À
the conditions described for the C N direct coupling.
[26] D. Astruc, Inorg. Chem. 2007, 46, 1884–1894.
[27] M. J. Climent, A. Corma, S. Iborra, M. Mifsud, Adv.
Synth. Catal. 2007, 349, 1949–1954.
[28] K. Itoh, F. Ueda, K. Hirai, Y. Ishii, Chem. Lett. 1977, 6,
877–880.
3660
asc.wiley-vch.de
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3648 – 3660