Hybrid polyoxometalate palladacycles: DFT study and application to the Heck reaction

Article abstract of DOI:10.1016/j.tet.2013.03.045

The phosphovanadotungstate polyanion [P₂W₁₅V ₃O₆₂]^9- is a powerful support to stabilize palladacycles conjugated to the inorganic framework via an organic ligand. The insertion can be directed toward sp² or sp³ C-H insertion upon appropriate choice of the substitution pattern on the organic ligand. DFT modeling indicates that the strong withdrawing effect of the POM transmitted through the conjugated carbonyl was responsible for this easy insertion. The palladacycles led to the formation of stilbene via a Mizoroki-Heck reaction. However it is likely that the POMs act as Pd-reservoirs for the formation of nanoparticles.

Full text of DOI:10.1016/j.tet.2013.03.045

Tetrahedron 69 (2013) 5772e5779
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Hybrid polyoxometalate palladacycles: DFT study and application
to the Heck reactionq
a
a
a
a,
*
ˇ
Benoît Riflade , Julie Oble , Ludwig Chenneberg , Etienne Derat
,
Bernold Hasenknopf a , Emmanuel Lacote
UPMC Sorbonne Universites, Institut Parisien de Chimie Moleculaire, UMR CNRS 7201, 4 place Jussieu, 75005 Paris, France
, Serge Thorimbert
,
a,
b,
a,
*
*
*
a
ꢀ
ꢀ
b
ꢀ
ꢀ
Universite de Lyon, Institut de chimie de Lyon, UMR 5265, CNRS, Universite Lyon I, ESCPE Lyon, 43 Bd du 11 novembre 1918, 69616 Villeurbanne, France
a r t i c l e i n f o
a b s t r a c t
9ꢀ
is a powerful support to stabilize palladacycles
Article history:
The phosphovanadotungstate polyanion [P2W15V3O62
]
conjugated to the inorganic framework via an organic ligand. The insertion can be directed toward sp2 or
sp3 CeH insertion upon appropriate choice of the substitution pattern on the organic ligand. DFT
modeling indicates that the strong withdrawing effect of the POM transmitted through the conjugated
carbonyl was responsible for this easy insertion. The palladacycles led to the formation of stilbene via
a MizorokieHeck reaction. However it is likely that the POMs act as Pd-reservoirs for the formation of
nanoparticles.
Received 27 January 2013
Received in revised form 6 March 2013
Accepted 11 March 2013
Available online 15 March 2013
Keywords:
Hybrid polyoxometalate
Catalysis
Ó 2013 Elsevier Ltd. All rights reserved.
Heck reaction
CeH insertion
Palladacycles
1. Introduction
POM. Reaction of an aqueous solution of sodium tungstate and po-
tassium tetrachloropalladate at pH 5.5 delivered K2Na6[Pd2W10O36]$
Polyoxometalates (POMs) are anionic clusters composed of
transition metals at their highest oxidation state linked by oxido
ligands. Most of these structures contain metal atoms from group 5
or 6 (Molybdenum, Tungsten, Vanadium, Niobium) as is the case in
the most famous Anderson, Lindqvist, Keggin, and Dawson fami-
lies.1 However, inclusion of noble metal ions (Ru, Rh, Pd, Pt, Ir, Os,
Au, Ag) inside or outside these clusters has attracted growing at-
tention because it is a way to increase the structural diversity in
POM chemistry, as well as to add different redox and catalytical
properties, thus potentially enhancing existing reactivities or
accessing new ones.2
22H2O as chocolate-brown crystals. Both square planar Pd ions are
6ꢀ
linking two monolacunary Lindqvist units (W5O18
)
by a pairwise
connection of the terminal oxygens of the lacuna.4
Since these pioneering works, several research groups have fo-
cused on the synthesis and characterization of new palladium-
substituted polyoxometalates (Fig. 1),5 in particular the group of
Kortz.6 The palladium (II) ions in these structures are generally
coordinated in a square planar geometry to oxygens of lacunary
Keggin, or Dawson POMs.
Palladium-substituted POMs have gained a special prominence
since the seminal Knoth et al. 1986 report, which described the first
synthesis of a Pd-containing POM.3 Reaction of the lacunary Keggin
POM Na8H[A,
sired heteropolyanion [Pd3(A,
a
-W9PO34] with divalent Pd cations afforded the de-
a
-W9PO34)2]12ꢀ, as suggested by ele-
mental analysis and analogy to other divalent transition metal
cations. However, no structure could be obtained. The group of
Lawrance reported the first crystal structure of a Pd-substituted
q
We congratulate our wonderful friend and colleague Melanie for her award.
* Corresponding authors. Tel.: þ33 4 72 44 82 46; e-mail addresses: etienne.
Fig. 1. Examples of polyoxometalates containing palladium: [Pd2WO(H2O)
derat@upmc.fr (E. Derat), bernold.hasenknopf@upmc.fr (B. Hasenknopf), emmanuel.
(A-
a a g-H2SiW10O36
-SiW9O34)2]12ꢀ (left); [Pd2{WO(H2O)}{A, -PW9O34}2]10ꢀ (center); [
ˇ
lacote@univ-lyon1.fr (E. Lacote), serge.thorimbert@upmc.fr (S. Thorimbert).
Pd2(OAc)2]4ꢀ (right).
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.03.045

B. Riflade et al. / Tetrahedron 69 (2013) 5772e5779
5773
In 2003, one of us introduced
a new type of PdePOM
mixed system. PdCl2 was covalently linked to a functional organo-
POM containing pyridine appendages.7 The coordination of
the palladium to both pyridines of the Anderson POM
[MnMo6O18{(OCH2)3CNHCO(4-C5H4N)}2]3ꢀ induced the formation
of a coordination polymer that transformed into an anisotropic gel.
That same year, the Neumann group used the same strategy of
POM-grafted ligands to tune the electronic properties of metallo-
salen type derivatives (Fig. 2, left).8 They showed that the ‘poly-
oxometalate exerts a significant intramolecular electronic effect on
the metallosalen moiety leading to formation of an oxidized met-
allosalen moiety’, suggesting that there might be a ‘delocalized
hole’ at the metal center, which is specific to POMesalen hybrids.
Fig. 3. Structures of existing Pd-complexes of diolamide-capped Dawson
9ꢀ
[P2W15V3O62
]
ion 1.
POMepalladacycles. We then examined their behavior as catalysts
for the Heck coupling.
2. Results and discussion
Fig. 2. Examples of covalent POMePd hybrids: [Pd(salene(CH2)3Si)2O(SiW11O39)]4ꢀ (left);
[PdBr2(C10H17N2Si)2O(g
-SiW10O36)]4ꢀ (right).
2.1. Preparation of picolinic diolamide-capped POMs
Several additional examples of POMePd hybrids have been
described with different kind of linkages leading to new com-
plexes.9 An illustrative example was published by the Bonchio
group, who showed that Keggin-based hybrid bis-NHC compounds
were powerful catalysts for carbonecarbon coupling and dehalo-
genation reactions (Fig. 2, right).9a The POM protects the reactive Pd
center from decomposition via formation of nanoparticles, result-
ing in high TONs.
The general scheme for the preparation of the hybrid ligands
and palladacycles is presented in Scheme 1. The new diolamides
9e13 required for the study were prepared following our estab-
lished procedure, by coupling of the corresponding carboxylic es-
ters with the adequate diolamines16 in the presence of K2CO3 under
microwave irradiation. The yields ranged from 39% to 73% and were
mostly in the fifties.
The Neumann group very cleverly used ionic interactions to
devise new cooperative Pd/POM bimetallic hybrid catalytic sys-
tems. PdII(15-crown-5-phen)Cl2eH5PV2Mo10O40 was used to cata-
lyze the Wacker oxidation of 1-alkenes using nitrous oxide as the
terminal oxidant.10 A similar strategy was later employed by the
Wang group for the heterogenous aerobic oxidation of benzene.
The ion pairing is crucial to understand the high activity by the
proposed intramolecular electron transfer mechanism.11
Part of our interest in POMs chemistry consists in finding new
modified POM-catalysts for organic reactions, mainly Lewis acidic
ones.12 The conjugated diolamide-capped Dawson [P2W15V3O62 9ꢀ (1)
]
phosphovanadotungstate family we introduced13 has proved adept at
catalyzing the oxidation of sulfides with high chemoselectivity.14
We extended its potential by grafting picolinic amide derivatives
onto (1). The latter hybrids could complex Pd(OAc)2, generating
stable palladacycles 2e8 (Fig. 3), and were used as electrophilic
catalysts in the allylation of aldehydes and imines.15
From the catalytic point of view, the Pd atom of 2 did not change
oxidation state during the allylation reactions. We felt that new
reactivities might be derived from exploiting the rich redox
chemistry of palladium, especially given that the conjugated POM
framework could accommodate electrons and stabilize higher ox-
idation states of Pd.
Scheme 1. Preparation of the diol-amide ligands 9e13, the functionalized POMs 14e18
and the palladation yielding POMePd hybrids 19e21. The Pd forms an additional bond
with either R1 or R2, see Table 1.
The organohybrid ligands were then prepared following our
previously reported method.13 In a typical example, Dawson POM
(TBA)5H4[P2W15V3O62] (1) was reacted with amido-diol 9 and
30 mol % of para-toluenesulfonic acid (PTSA) in dimethylacetamide
(DMAc) under microwave heating at 80 ꢁC for 35 min (Table 1, entry
1). POM 14 was isolated in 82% yield after precipitation with Et2O
and centrifugation.
In the present article we first examined the competition
between CeH activation of a sp2 center vs a sp3 carbon and used
DFT modeling to understand better the easy formation of the

5774
B. Riflade et al. / Tetrahedron 69 (2013) 5772e5779
Table 1
Preparations of diolamides 9e13, hybrid POMs 14e18 and POM-palladacycles 19e20
Entry
Diolamide (yield%)
POM ligand
(yield%)
Palladation
(yield%)
1
14 (86)
19/190 (>80,a 1:1)
9 (48)
2
15 (83)
20 (89)
10 (54)
3
4
16 (86)
21b
Fig. 4. New structures examined in this article.
11 (39)
12 (48)
17 (86)
18 (93)
dc
5
dc
13 (73)
a
NMR yield.
b
c
Only coordination to Pd(OAc)2was observed.
No reaction took place (S. M. recovered).
The reaction worked well with all the new diolamides (86e93%,
see Table 1), and the ligand grafting to 1, leading to 14e18 was
confirmed by IR, ESI-MS, and multinuclear NMR methods (Fig. 4).
The organo-POMs were obtained as TBA salts with varying
amounts of dimethylammonium cations, as determined by NMR
and elemental analysis.
2.2. Palladation of 14e18
Scheme 2. Competitive formation of palladacycles for the POMs bearing a phenyl-
pyridine-diol-amide.
POMs 14e15 were submitted to the palladation conditions. A
solution of the POM ligand was reacted with one equiv of Pd(OAc)2
at rt in acetonitrile. This gave a clear solution in less than 5 min.15
For substrate 14, there is a competition between the CeH in-
sertion at the sp3 carbon of the ethyl group, and that at the sp2 one
on the attached phenyl ring. In this case, we observed the formation
of both palladacycles 19 and 190 in a 1:1 ratio and >80% yield, as
shown by NMR analysis (Table 1, entry 1 and Scheme 2). When the
ethyl was replaced with a hydrogen atom, the competition dis-
appeared and the CeH insertion only took place at the ortho phenyl
substituent to yield 89% of isolated 20 (Table 1, entry 2 and Scheme
2). On the other hand, replacement of the phenylpyridine with
a bipyridyl blocked the CeH insertion at the methyl site (Table 1,
entry 3). We did not attempt to isolate the palladium complexes in
that case.
Finally, no palladation at all took place on the diol-benzamide
POM 17, and only starting material was recovered (entry 4).
When a quinolylamide was used, as in POM 18, no CeH activation
was observed (entry 5).
In summary, we can prepare pincer-type hybrids with the Pd
atom attached either at the ethyl substituent or at the phenyl in the
6-position of the pyridyl ring, depending on the choice of sub-
stituents on the diolamides. However, there is no real preference
for one or the other, at least in the simplest case. On the other hand,
the palladation requires a pyridyl ring next to the POM-inserted
carbonyl. A phenyl group cannot anchor the Pd for the insertion
to proceed, and a quinolyl adds too much steric strain for the pal-
ladacycle to form.

B. Riflade et al. / Tetrahedron 69 (2013) 5772e5779
5775
2.3. DFT study
We decided to rationalize this very easy and efficient palladation
through CeH activation with the use of DFT. In particular we
wished to confirm the role of the POM.
The first system treated by DFT was the monopyridine POM
vanadate 2 with the palladium complexed by one molecule of
acetonitrile. We chose acetate as the base to match the experi-
mental conditions (Fig. 5).
Fig. 7. Modeling of the palladation from 16. Calculations carried out at the BP86/SV(P)
level, energies are in kcal/mol.
was also higher (29.49 kcal/mol versus 18.54 kcal/mol), making the
insertion less favorable. This matched the experimental observa-
tions (Table 1, entry 3).
Models (A) and (C) were used in order to support the influence
of the polyoxometalate on the CeH activation process (Scheme 3).
In model (A), the inorganic part was removed but the organome-
tallic framework was kept identical (Scheme 3a). In that case, the
barrier for the CeH activation to B was found to be 31.15 kcal/mol.
Thus it is clear that the polyoxometalate moiety has a positive effect
on the CeH activation.
Fig. 5. Modeling of the palladation leading to 2. Calculations carried out at the BP86/
SV(P) level, energies are in kcal/mol.
Two minima were found before the CeH activation. One in-
volves the acetate directly coordinated to the palladium center and
one has an agostic interaction between the palladium and one CeH
ꢁ
bond of the ethyl chain (PdeH distance of 1.912 A). The agostic
interaction is disfavored by only 5.24 kcal/mol. The transition state
yielding 2 was found to be 18.54 kcal/mol. This is compatible with
the experimental outcome (easy insertion into the CeH bond).
When the carbonyl was reduced (use of a theoretical structure
featuring an inserted hemi-aminal, Fig. 6), thus breaking the con-
jugation between the organic part and the inorganic framework,
the barrier was found even higher at 41.69 kcal/mol.
Scheme 3. Modeling of the hypothetical palladation of (a) the ligand alone (A) and (b)
the same ligand without the gem-diol moiety (C). Calculations carried out at the BP86/
SV(P) level, energies are in kcal/mol.
In 2005, Daugulis et al. have published a study in which they
demonstrate that palladium complexes similar to the ones used
here are able to activate sp3 CeH bond.17 Complex (C) without the
gem-diol part is representative of their work (Scheme 3b). We
found an activation barrier at 21.96 kcal/mol, lower than for A. This
value is again compatible with the observed experimental facts of
the Daugulis group.
Fig. 6. Modeling of the palladation of a hypothetical hemi-aminal POM hybrid. Cal-
culations carried out at the BP86/SV(P) level, energies are in kcal/mol.
The main differences between complexes (A) and (C) are (i)
the gem-dihydroxyl group and (ii) the presence of acetonitrile
as a solvent/ligand. It is possible that acetonitrile disfavors the
chelation of the acetate on palladium, which results in an increase
of the barrier for the CeH activation. It may also be that the gem
disubstitution introduces strain. In any case, these negative
effects are largely compensated by the polyoxometalate electronic
effect.
The electrostatic potentials of palladacycles 2 and B were plot-
ted (Fig. 8). In 2, the palladium center is electron-rich while in B it is
electron-poor. This shows that the polyoxometalate has a direct
influence on the electronic structure of the organometallic moiety
because of the conjugation.
We can conclude that the POM was able to activate the palla-
dium CeH insertion step. The strong electron-withdrawing effect of
the POM framework is likely transmitted to the palladium center
via the inserted conjugated carbonyl, thus making it more elec-
trophilic. As a consequence, the agostic interaction and/or the
deprotonation with the acetate are favored, leading to the insertion.
When a bipyridine ligand was installed on the POM (palladation
of 16, Fig. 7), the palladium was coordinated by the amide nitrogen
and the two nitrogens of the bipyridyl moiety. An agostic complex
was also found in that case, but much higher in energy (11.66 kcal/
mol versus 5.24 kcal/mol). And the corresponding transition state

5776
B. Riflade et al. / Tetrahedron 69 (2013) 5772e5779
catalyst. Palladium pincer complexes are considered to be pre-
cursors of palladium nanoparticles.19 In our system, the basic and
thermal conditions required to perform the reaction are likely re-
sponsible for the degradation of the POM, releasing the palladium
for the nanoparticle formation.
2.5. Conclusion
9ꢀ
Fig. 8. Electrostatic potential mapped on electron density for model system 2 and B.
Red area represents an excess of electron while blue area indicates electronic
depletion.
The phosphovanadotungstate polyanion [P2W15V3O62
]
is
a powerful support for organic ligands and the resulting hybrids
stabilize palladacycles conjugated to the inorganic framework. One
can direct the CeH insertion upon appropriate choice of the sub-
stitution pattern. DFT modeling showed that the strong electron
withdrawing effect of the POM transmitted through the conjugated
carbonyl was responsible for this easy insertion. The Mizor-
okieHeck reaction proceeded toward formation of stilbene in the
presence of the palladacycles. However it is likely that the POMs act
as Pd-reservoirs for the formation of nanoparticles. Further work
will focus on extending the CeH insertion to other metals.
2.4. MizorokieHeck reaction
We next examined the potential of the palladacycles as
catalysts for reactions involving redox steps at Pd. We selected the
MizorokieHeck coupling of iodobenzene and styrene as a bench-
mark reaction. Those reactions generally require two open sites on
palladium to proceed. However, it has been suggested that some
single-site Pd(II) systems might proceed via a Pd(IV) species,18
which the POM might stabilize.
In a first experiment, iodobenzene (1 equiv) and styrene
(2 equiv) were mixed in the presence of Na2CO3 (1.2 equiv) and
palladacycle 2 (1 mol %) in acetonitrile at 80 ꢁC. An encouraging 28%
yield of stilbene was obtained after 20 h (Table 2, entry 1). When
the coordinating solvent CH3CN was replaced by DMSO or DMF, the
yields improved to 75 and 87% (entries 2 and 3). The use of an or-
ganic base, such as NEt3 did not affect significantly the yield in
stilbene (entry 4). Finally, microwave heating was extremely det-
rimental (entries 5 and 6).
3. Experimental section
3.1. Computational details
The TURBOMOLE20 software was used to perform QM (DFT)
calculations using the B-P86 functional, within the framework of
the RI-J approximation.21 The SV(P) basis set developed by Ahl-
richs22 was used for geometry optimization. Despite the large size
of the Dawson POM, frequency calculations were performed to
ascertain the nature of the intermediates. We recently used this
level of calculation to study the regioselective activation of
organotin-substituted Dawson POMs [a1-P2W17O61SnR]7ꢀ 23
The
.
Table 2
description of the latter systems correlated well with their ob-
served behaviors and can thus be considered accurate enough for
our purpose. Solvent effects induced by acetonitrile (dielectric
constant was set to 36.64) were taken into account by turning on
the COSMO implementation.
POMePd hybrid-catalyzed MizorokieHeck reaction
Entry
POM
Solvent
Base
Time (h)
Yield (%)
3.2. Materials
1
2
3
4
5
6
7
8
2
2
2
2
2
2
3
5
6
8
20
CH3CN
DMSO
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
Na2CO3
Na2CO3
Na2CO3
NEt3
Na2CO3
NEt3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
20
20
20
20
1a
28
75
87
84
37
42
83
75
87
82
78
Reagents and chemicals were purchased from commercial
sources and used as received. The starting TBA5H4[P2V3W15O62] was
prepared as described in the literature24 (Anal. Calcd for TBA5.3(-
Me2NH2)3.7P2V3W15O62.DMF$H2O (5344.40 g molꢀ1): C 19.73, H
3.84, N 1.65; found: C 19.74, H 3.83, N 1.65). Unless otherwise noted,
reactions were carried out under argon atmosphere with magnetic
stirring in redistilled solvents when necessary. 6-Phenyl-pyridine-
2-carboxylic acid and 2,20-dipyridyl-6-carboximidic acid methyl
ester were prepared as described in the literature.25 Compounds 12
and 17 were prepared as described in a previous publication from
our laboratory.13 Merck 60F254 silica gel was used for thin-layer
1a
20
20
20
20
20
9
10
11
a
Microwave irradiation.
With the optimized conditions of entry 3 in hands, we probed
the catalytic activity of other hybrid POM palladacycles. ortho-
Substituents (electron donating or electron withdrawing) on the
pyridyl moiety did not affect the catalysis. Stilbene was always
isolated in good yields (entries 7e9). The aryl-palladium POM
species 8 and 20 also catalyzed the reaction (respectively, 82 and
78% yield, entries 10 and 11). However, in all cases the reaction
turned black after a few hours, raising questions on the exact nature
of the catalytic species. To answer the question of stability of our
palladacycles in these reaction conditions, we turned our attention
to the possible recycling of the catalysts.
We tried to recover the catalysts by precipitation in Et2O. No
matter which POM we tried to recover, the only recovered solid
material was a dark powder, which was not the POM. The degra-
dation of the POM catalyst into a black material suggests the for-
mation of palladium nanoparticles that might well be the true
ꢁ
chromatography (TLC) and Merck Geduran SI 60 A silica gel 60
(40e63 mM) was used for flash column chromatography. Melting
points were measured on a Stuart Scientific Melting Point SMP3
apparatus in open capillaries. IR spectra were recorded from
a Bruker Tensor 27 ATR diamond PIKE spectrophotometer. NMR 1H,
31P, 13C spectra were recorded at 400, 162, and 100 MHz, re-
spectively, using a Bruker AVANCE 400 spectrometer equipped with
a BBFO probe. Some 13C NMR spectra were recorded at 50 MHz using
a Bruker Avance 200. Chemical shifts are reported in parts per mil-
lion, using, for 1H and 13C, solvent residual peak as internal standard
references, and for 31P external H3PO4. Coupling constants (J) are
given in Hertz (Hz), multiplicity (s¼singlet, d¼doublet, t¼triplet,
q¼quartet, m¼multiplet). Mass spectrometry experiments have
been carried out on an electrospray-ion trap instrument (Bruker,
Esquire 3000). The 50 m
mol Lꢀ1 solutions of POMs were infused

B. Riflade et al. / Tetrahedron 69 (2013) 5772e5779
5777
using a syringe pump (160
m
L hꢀ1). The negative ion mode was used
1H, arom.), 8.07 (dd, J¼7.6, 0.8 Hz, 1H, arom.), 7.89 (t, J¼7.8 Hz, 1H,
arom.), 7.78 (td, J¼7.8, 1.7 Hz, 1H, arom.), 7.29 (ddd, J¼7.6, 4.8,
0.8 Hz, 1H, arom.), 4.53 (s, 2H, OH), 3.96 (A of AB, J¼11.7 Hz, 2H,
CHHOH), 3.73 (B of AB, J¼11.7 Hz, 2H, CHHOH), 1.81 (q, J¼7.5 Hz, 2H,
CH2Me), 0.97 (t, J¼7.5 Hz, 3H, CH2Me). 13C NMR (100 MHz, CDCl3):
with capillary high voltage 3500 V. The orifice/skimmer voltage
difference was set to 45 V to avoid decomposition of the POMs. The
low-mass-cutoff (LMCO) of the ion trap was set to 80 Th. Elemental
analyses were carried out by ICSN (CNRS, Gif, France).
d
¼165.0 (C]O), 154.9 (C arom.), 154.7 (C arom.), 149.5 (C arom.),
3.3. Preparation of the diolamides
149.2 (CH arom.), 138.7 (CH arom.), 137.3 (CH arom.), 124.4 (CH
arom.), 123.9 (CH arom.), 122.1 (CH arom.), 121.1 (CH arom.), 65.8
(CH2OH), 61.3 (CNH), 25.9 (CH2Me), 7.8 (CH2Me). HRMS calcd for
C16H19N3O3Na: 324.1324; found: 324.1329.
3.3.1. Diolamide 9. Methyl chloroformate (116
1 equiv) was slowly added to a solution of 6-phenyl-pyridine-2-
mL, 1.5 mmol,
carboxylic acid (300 mg, 1.5 mmol, 1 equiv) and Et3N (230
mL,
1.7 mmol, 1.13 equiv) in THF (30 mL) at 0 ꢁC and the resulting
mixture was stirred in an ice bath for 30 min. Then, the white
precipitate of triethylammonium chloride was removed by filtra-
tion. A clear solution of the mixed anhydride was thus obtained and
3.3.4. Diolamide 13. Ethyl quinoline-8-carboxylate (200 mg,
1
mmol, 1 equiv), 2-amino-2-ethylpropane-1,3-diol (131 mg,
1.1 mmol, 1.1 equiv), and K2CO3 (151 mg, 1.1 mmol, 1.1 equiv) were
dissolved in DMSO (3 mL) in a sealed microwave vial containing
a stir bar. The mixture was heated under MW to 100 ꢁC for 45 min.
The suspension was filtered and the solvent was evaporated under
reduced pressure (water bath 90 ꢁC). The crude material was pu-
rified by column chromatography (DCM/MeOH: 90/10) to afford the
diol-amide 13 as an orange oil (200 mg, 0.73 mmol, 73% yield). IR:
was added to
(178 mg, 1.5 mmol, 1 equiv) and Et3N (230
a
solution of 2-amino-2-ethylpropane-1,3-diol
L, 1.7 mmol,
m
1.13 equiv) in THF. The reaction mixture was stirred overnight, and
then concentrated. The crude material was purified by column
chromatography (petroleum ether/EtOAc: 50/50) to afford the diol-
amide 9 as a white solid (216 mg, 0.72 mmol, 48% yield). Mp 79.9 ꢁC.
n
¼3378, 2968, 1639, 1572, 1054, 796 cmꢀ1
.
1H NMR (400 MHz,
IR:
n
¼3341, 2930, 1658, 1529, 1447, 1052, 753 cmꢀ1
.
1H NMR
CDCl3):
d
¼11.67 (br s, 1H, NH), 8.92 (dd, J¼4.3, 1.9 Hz, 1H, arom.),
(400 MHz, CDCl3):
d
¼8.75 (br s, 1H, NH), 8.12 (dd, J¼7.4, 1.3 Hz, 1H,
8.80 (dd, J¼7.9, 1.9 Hz, 1H, arom.), 8.31 (dd, J¼8.3, 1.4 Hz, 1H, arom.),
7.99 (dd, J¼8.3, 1.4 Hz, 1H, arom.), 7.69 (t, J¼8.3 Hz, 1H, arom.), 7.52
(dd, J¼7.9, 4.3 Hz, 1H, arom.), 4.48 (br s, A of AB, 2H, CHHOH), 4.09
(d, J¼12.2 Hz, 2H, OH), 3.77 (B of AB, J¼12.2 Hz, 2H, CHHOH),1.86 (q,
J¼7.6 Hz, 2H, CH2Me), 1.13 (t, J¼7.6 Hz, 3H, CH2Me). 13C NMR
arom.), 8.01e7.98 (m, 2H, arom.), 7.95e7.88 (m, 2H, arom.),
7.54e7.45 (m, 3H, arom.), 4.07 (br s, 2H, OH), 4.01 (A of AB, J¼11.7,
2H, CHHOH), 3.74 (B of AB, J¼11.7 Hz, 2H, CHHOH), 1.82 (q, J¼7.6 Hz,
2H, CH2Me), 1.05 (t, J¼7.6 Hz, 3H, CH2Me). 13C NMR (100 MHz,
CDCl3):
d
¼165.4 (C]O), 156.0 (C arom.), 149.6 (C arom.), 138.6 (CH
(100 MHz, CDCl3):
d¼167.1 (C]O), 149.4 (CH arom.), 145.6 (C
arom.), 138.2 (C arom.), 129.7 (CH arom.), 129.1 (CH arom.), 126.9
(CH arom.), 123.3 (CH arom.), 120.6 (CH arom.), 65.9 (CH2OH), 61.3
(CNH), 26.7 (CH2Me), 7.7 (CH2Me). HRMS calcd for C17H20N2O3Na:
323.1366; found: 323.1356.
arom.), 138.1 (CH arom.), 133.9 (CH arom.), 132.4 (CH arom.), 128.9
(C arom.), 128.9 (C arom.), 126.7 (CH arom.), 121.2 (CH arom.), 66.1
(CH2OH), 62.3 (CNH), 27.4 (CH2Me), 7.8 (CH2Me). HRMS calcd for
C15H18N2O3Na: 297.1210; found: 297.1229.
3.3.2. Diolamide 10. Methyl chloroformate (116
1 equiv) was slowly added to a solution of 6-phenyl-pyridine-2-
carboxylic acid (300 mg, 1.5 mmol, 1 equiv) and Et3N (230 L,
m
L, 1.5 mmol,
3.4. GP1: preparation of the hybrid polyoxometalate ligands
m
TBA5.7H3.3[P2V3W15O62] (300 mg, 0.058 mmol, 1 equiv), PTSA
(2.2 mg, 0.012 mmol, 0.2 equiv), and the diol-amide (0.069 mmol,
1.2 equiv) were dissolved in DMA (0.6 mL) in a sealed microwave
vial containing a stir bar. The reaction was heated to 80 ꢁC under
1.7 mmol, 1.13 equiv) in THF (30 mL) at 0 ꢁC and the mixture was
stirred in an ice bath for 30 min. The white precipitate of triethy-
lammonium chloride was removed by filtration. A clear solution of
the mixed anhydride was thus obtained and was added to a solu-
tion of 2-amino-propane-1,3-diol (137 mg, 1.5 mmol, 1 equiv) and
mW for 35 min (with stirring). The reaction mixture was then
quickly transferred to a round-bottom flask with a minimal amount
of acetonitrile. The combined solvents were removed in vacuo. The
crude yellow oil was dissolved with a minimal amount of aceto-
nitrile and then transferred to a round-bottom 50 mL glass cen-
trifuge tube and Et2O (30 mL) was added to precipitate the product
as a yellow powder (sometimes a yellow-brown paste also formed,
which transformed into the same powder upon trituration with
a spatula). After centrifugation, the colorless supernatant was re-
moved from the tube, and the powder was air-dried. It was then
redissolved in a minimal amount of acetonitrile (less than 0.5 mL is
required), precipitated with ethanol (30 mL), triturated if needed,
and centrifugated again. The orange supernatant was discarded and
the remaining solid was triturated in diethyl ether. The ether was
removed by centrifugation. The resulting powder was then finely
dried under vacuum to afford the pure functionalized POMs.
Et3N (230 mL, 1.7 mmol,1.13 equiv) in THF. The reaction mixture was
stirred overnight, and then concentrated. The crude material was
purified by column chromatography (petroleum ether/EtOAc: 50/
50) to afford the diol-amide 10 as a white solid (220 mg, 0.81 mmol,
54% yield). Mp 118.3 ꢁC. IR:
n
¼3367, 2946, 1656, 1526, 1446, 1047,
753 cmꢀ1 1H NMR (400 MHz, CDCl3):
.
d
¼8.79 (br s, 1H, NH), 8.10
(dd, J¼7.3, 1.5 Hz, 1H, arom.), 8.01e7.98 (m, 2H, arom.), 7.90e7.83
(m, 2H, arom.), 7.52e7.42 (m, 3H, arom.), 4.18e4.13 (m, 1H, CHNH),
3.99e3.91 (m, 4H, CHHOH and OH), 3.15 (br s, 2H, CHHOH). 13C
NMR (100 MHz, CDCl3):
d
¼165.4 (C]O), 156.2 (C arom.), 149.4 (C
arom.), 138.4 (CH arom.), 138.2 (C arom.), 129.7 (CH arom.), 129.0
(CH arom.), 127.1 (CH arom.), 123.3 (CH arom.), 120.8 (CH arom.),
63.5 (CH2OH), 53.1 (CHNH). HRMS calcd for C15H16N2O3Na:
295.1058; found: 295.1070.
3.3.3. Diolamide 11. 2,20-Dipyridyl-6-carboximidic acid methyl es-
ter (108 mg, 0.51 mmol, 1 equiv) was added to a solution of 2-
amino-2-ethylpropane-1,3-diol (61 mg, 0.51 mmol, 1 equiv) in
chlorobenzene (5 mL) at rt. The reaction mixture was refluxed for
three days, and then concentrated. The crude material was purified
by column chromatography (petroleum ether/EtOAc: 50/50) to af-
ford the diol-amide 11 as a pale yellow oil (63 mg, 0.19 mmol, 39%
3.4.1. POMligand14. Following GP1 from the diol-amide 9 (20.7 mg,
0.069 mmol). POM 14 was isolated as a yellow powder (264 mg,
0.049 mmol, 86% yield). IR:
n
¼2961, 2874, 1623, 1580, 1483, 1482,
1380, 1085, 951, 900, 805, 731 cmꢀ1
.
1H NMR (400 MHz, CD3CN):
d
¼10.52 (br s, 1H, NH), 8.76 (d, J¼6.4, 2.1 Hz, 1H, arom.), 8.17e8.14
(m, 2H, arom.), 7.58e7.52 (m, 3H, arom.), 6.93 (br s, 0.4H, Me2NH2),
5.68 (A of AB, J¼12.8 Hz, 2H, CHHOV), 5.55 (B of AB, J¼12.8 Hz, 2H,
CHHOV), 3.19e3.15 (m, 38.4H, N(CH2CH2CH2Me)4), 3.02 (br s, 1.2H,
Me2NH2), 1.99 (q, J¼7.7 Hz, 2H, CH2Me), 1.69e1.61 (m, 38.4H,
N(CH2CH2CH2Me)4), 1.47e1.38 (m, 38.4H, N(CH2CH2CH2Me)4), 1.19
yield). IR:
760 cmꢀ1. 1H NMR (400 MHz, CDCl3)
(m, 1H, arom.), 8.47 (dd, J¼7.9, 0.8 Hz, 1H, arom.), 8.24 (d, J¼7.9 Hz,
n
¼3345, 3065, 2955, 1658, 1529, 1437, 1042, 902,
d
¼8.72 (s, 1H, NH), 8.66e8.61

5778
B. Riflade et al. / Tetrahedron 69 (2013) 5772e5779
(t, J¼7.7 Hz CH2Me), 1.01e0.97 (m, 57.6H, N(CH2CH2CH2Me)4). 13C
arom.), 140.4 (CH arom.), 139.6 (CH arom.), 136.5 (CH arom.), 128.1
(C arom.), 126.8 (CH arom.), 122.6 (CH arom.), 121.4 (C arom.), 88.7
(CH2OV), 62.9 (CNH), 59.2 (N(CH2CH2CH2Me)4), 35.7 (Me2NH2),
28.5 (CH2Me), 23.1 (N(CH2CH2CH2Me)4), 19.2 (N(CH2CH2CH2Me)4),
13.5 (N(CH2CH2CH2Me)4), 7.2 (CH2Me). 31P NMR (162 MHz,
NMR (100 MHz, CD3CN):
d
¼179.1 (C]O), 158.1 (C arom.), 145.9 (C
arom.), 140.7 (CH arom.),138.1 (C arom.), 131.2 (CH arom.), 130.0 (CH
arom.), 128.2 (CH arom.), 127.6 (CH arom.), 127.1 (CH arom.), 89.9
(CH2OV), 64.3 (CNH), 59.3 (N(CH2CH2CH2Me)4), 36.5 (Me2NH2), 29.1
(CH2Me), 24.5 (N(CH2CH2CH2Me)4), 20.4 (N(CH2CH2CH2Me)4), 14.1
(N(CH2CH2CH2Me)4), 7.1 (CH2Me). 31P NMR (162 MHz, CD3CN)
CD3CN)
d
¼ꢀ5.69 (s, 1P), ꢀ11.80 (s, 1P). Anal. Calcd for TBA4.7(-
Me2NH2)0.3C15H16N2O62P2V3W15 (5342.21 g molꢀ1): C 20.41, H
3.54, N 1.83; found: C 20.64, H 3.42, N 1.87.
d
¼ꢀ5.71 (s, 1P), ꢀ11.74 (s, 1P). Anal. Calcd for TBA4,8(-
Me2NH2)0.2C17H18N2O62P2V3W15 (5387.88 g molꢀ1): C 20.99, H 3.59,
N 1.81; found: C 21.23, H 3.65, N 1.83.
3.5. Palladacycle 20
3.4.2. POM ligand 15. Following GP1 from the diol-amide 10
(18.7 mg, 0.069 mmol). POM 15 was isolated as a yellow powder
POM 15 (100 mg, 0.019 mmol, 1 equiv) and Pd(OAc)2 (4 mg,
0.019 mmol, 1 equiv) were dissolved in CD3CN and transferred in
a sealed tube. The mixture was stirred for 5 min at rt and treated as
in GP1 to afford the pure functionalized POM 20 (91 mg,
(253 mg, 0.048 mmol, 83% yield). IR:
1484, 1380, 1086, 954, 900, 804, 760, 731 cmꢀ1. 1H NMR (400 MHz,
CD3CN):
n¼2962, 2874, 1623, 1582,
d¼11.39 (d, J¼6.7 Hz, 1H, NH), 8.71 (dd, J¼6.4, 2.2 Hz, 1H,
0.017 mmol, 89% yield). IR:
n
¼2963, 1581, 1484, 1382, 1087, 1052,
1024, 951, 904, 811, 734 cmꢀ1
.
1H NMR (400 MHz, DMSO-d6):
arom.), 8.27e8.25 (m, 4H, arom.), 7.59 (t, J¼7.7 Hz, 2H, arom.), 7.52
(dd, J¼7.7,1.2 Hz,1H, arom.), 6.79 (br s,1.2H, Me2NH2), 5.98 (A of AB,
J¼12.3 Hz, 2H, CHHOV), 5.64 (B of AB, J¼12.3 Hz, 2H, CHHOV), 4.61
(br s, 1H, CHNH), 3.16e3.13 (m, 32.5H, N(CH2CH2CH2Me)4), 2.96 (br
s, 3.6H, Me2NH2), 1.67e1.61 (m, 35.2H, N(CH2CH2CH2Me)4),
1.44e1.38 (m, 35.2H, N(CH2CH2CH2Me)4), 1.00e0.98 (m, 52.8H,
d
¼8.26 (br s, 1H, arom.), 8.10 (br s, 1H, arom.), 8.01 (d, J¼8.1 Hz, 1H,
arom.), 7.76 (br s, 1H, arom.), 7.20 (m, 3H, arom.), 5.71 (A of AB,
J¼11.8 Hz, 2H, CHHOV), 5.44 (B of AB, J¼11.8 Hz, 2H, CHHOV), 4.24
(br s, 1H, CHNH), 3.18e3.16 (m, 38.4H, N(CH2CH2CH2Me)4),
1.58e1.56 (m, 38.4H, N(CH2CH2CH2Me)4), 1.34e1.30 (m, 38.4H,
N(CH2CH2CH2Me)4), 0.94e0.92 (m, 57.6H, N(CH2CH2CH2Me)4).
N(CH2CH2CH2Me)4). 13C NMR (100 MHz, CD3CN):
d
¼179.6 (C]O),
13C NMR (100 MHz, DMSO-d6):
d
¼175.0 (C]O), 164.1 (C arom.),
158.4 (C arom.), 145.8 (C arom.), 140.5 (CH arom.), 138.1 (C arom.),
131.5 (CH arom.), 130.0 (CH arom.), 128.3 (CH arom.), 127.4 (CH
arom.), 127.3 (CH arom.), 85.7 (CH2OV), 59.3 (N(CH2CH2CH2Me)4),
57.2 (CNH), 36.8 (Me2NH2), 24.4 (N(CH2CH2CH2Me)4), 20.4
(N(CH2CH2CH2Me)4), 13.9 (N(CH2CH2CH2Me)4). 31P NMR (162 MHz,
151.2 (C arom.), 146.5 (C arom.), 141.7 (CH arom.), 133.5 (CH arom.),
130.6 (CH arom.), 126.1 (CH arom.), 125.4 (CH arom.), 124.6 (CH
arom.), 121.5 (CH arom.), 118.1 (CH3CN), 83.7 (CH2OV), 59.9
(CH), 57.4 (N(CH2CH2CH2Me)4), 23.1 (N(CH2CH2CH2Me)4), 19.2
(N(CH2CH2CH2Me)4), 13.5 (N(CH2CH2CH2Me)4), 0.7 (CH3CN). 31P
CD3CN)
d
¼ꢀ5.91 (s, 1P), ꢀ11.48 (s, 1P). Anal. Calcd for TBA4,4(-
Me2NH2)0.6C15H14N2O62P2V3W15 (5281.28 g molꢀ1): C 19.69, H
3.38, N 1.85; found: C 19.76, H 3.44, N 1.91.
NMR (162 MHz, CD3CN)
d
¼ꢀ5.99 (s, 1P), ꢀ11.96 (s, 1P). Anal. Calcd
for TBA4.8H0.2C15H12N2O62PdP2V3W15 (5348.80 g molꢀ1): C 20.61, H
3.48, N 1.78; found: C 20.82, H 3.48, N 1.85.
3.4.3. POM ligand 16. Following GP1 from the diol-amide 11
(18.7 mg, 0.069 mmol). POM 16 was isolated as a yellow powder
3.6. Heck reaction
(256 mg, 0.048 mmol, 86% yield). IR:
n
¼2955, 2890,1625,1578,1385,
1091, 951, 894, 755, 732 cmꢀ1. 1H NMR (400 MHz, CD3CN)
d¼8.87 (d,
Iodobenzene (110
styrene (228 L, 2 mmol, 2 equiv), the POM catalyst (0.01 mmol,
0.01 equiv) and Na2CO3 (127 mg, 1.2 mmol, 1.2 equiv) or Et3N
mL,1 mmol,1 equiv) was added to a mixture of
J¼7.7 Hz, 1H, arom.), 8.77 (d, J¼7.8 Hz, 1H, arom.), 8.74 (br s, 1H,
arom.), 8.54 (d, J¼7.7 Hz,1H, arom.), 8.27 (t, J¼7.8 Hz,1H, arom.), 8.03
(br s, 1H, arom.), 7.53 (br s, 1H, arom.), 5.66 (A of AB, J¼12.6 Hz, 2H,
CHHOH), 5.52 (B of AB, J¼12.6 Hz, 2H, CHHOH), 3.19e3.16 (m, 40H,
N(CH2CH2CH2Me)4), 2.02e2.01 (m, 2H, CH2Me), 1.65e161 (m, 40H,
N(CH2CH2CH2Me)4), 1.45e1.39 (m, 40H, N(CH2CH2CH2Me)4), 1.20 (t,
m
(162 mL, 1.2 mmol, 1.2 equiv) in 0.5 mL of DMF, DMSO or CH3CN. The
solution was over after 20 h at 80 ꢁC.
J¼7.8 Hz, 3H, CH2Me), 0.99e0.96 (m, 60H, N(CH2CH2CH2Me)4). 13
C
Acknowledgements
NMR (100 MHz, CD3CN):
d
¼178.9 (C]O), 156.9 (C arom.), 154.4 (C
ꢀ
We thank Universite P. et M. Curie (UPMC), CNRS and ANR (grant
arom.),153.3 (CH arom.),145.9 (CH arom.),140.6 (CH arom.),138.8 (C
arom.), 128.7 (CH arom.), 127.4 (CH arom.), 126.2 (CH arom.), 122.3
(CH arom.), 89.7 (CH2OV), 64.3 (CNH), 59.2 (N(CH2CH2CH2Me)4),
29.1 (CH2Me), 24.4 (N(CH2CH2CH2Me)4), 20.4 (N(CH2CH2CH2Me)4),
14.0 (N(CH2CH2CH2Me)4), 7.7 (CH2Me). 31P NMR (162 MHz, CD3CN)
number 08-PCVI-0005 to E.L., S.T. and B.H.) for funding. FR2769 is
acknowledged for technical assistance.
Supplementary data
d
¼ꢀ5.70 (s, 1P), ꢀ11.86 (s, 1P). Anal. Calcd for TBA5C16H17
-
N3O62P2V3W15 (5428.15 g molꢀ1): C 21.24, H 3.65, N 2.09; found: C
21.06, H 3.62, N 1.98.
NMR spectra of new compounds. Supplementary data
related to this article can be found at http://dx.doi.org/10.1016/
j.tet.2013.03.045.
3.4.4. POM ligand 18. Following GP1 from the diol-amide 13
(18.9 mg, 0.069 mmol). POM 18 was isolated as a yellow powder
References and notes
(288 mg, 0.054 mmol, 93% yield). IR:
1483, 1087, 952, 901, 811, 731 cmꢀ1. 1H NMR (400 MHz, DMSO-d6):
¼14.89 (br s, 1H, NH), 9.34 (dd, J¼7.5, 1.7 Hz, 1H, arom.), 9.18 (dd,
n
¼2964, 2871, 1661, 1599,
1. (a) Hill, C. L. In Comprehensive Coordination Chemistry II; Wedd, A. G., Ed.;
Elsevier: Oxford, UK, 2004; Vol. 4, pp 679e759; (b) Pope, M. T. In Comprehensive
Coordination Chemistry II; Wedd, A. G., Ed.; Elsevier: Oxford, UK, 2004; Vol. 4,
pp 635e678; (c) Proust, A.; Thouvenot, R.; Gouzerh, P. Chem. Commun. 2008,
1837e1852; (e) Dolbecq, A.; Dumas, E.; Mayer, C. R.; Mialane, P. Chem. Rev. 2010,
110, 6009e6048; (f) Long, D.-L.; Tsunashima, R.; Cronin, L. Angew. Chem., Int. Ed.
2010, 49, 1736e1758; (g) Oms, O.; Dolbecq, A.; Mialane, P. Chem. Soc. Rev. 2012,
41, 7497e7536.
2. (a) Putaj, P.; Lefebvre, F. Coord. Chem. Rev. 2011, 255, 1642e1685; (b) Izarova, N.;
Pope, M. T.; Kortz, U. Angew. Chem., Int. Ed. 2012, 51, 9492e9510.
3. Knoth, W. H.; Domaille, P. J.; Harlow, R. L. Inorg. Chem. 1986, 25, 1577e1584.
4. Angus-Dunne, S.; Burns, R. C.; Craig, D. C.; Lawrance, G. A. J. Chem. Soc., Chem.
Commun. 1994, 523e524.
d
J¼4.4, 1.7 Hz, 1H, arom.), 8.82 (dd, J¼8.6, 1.4 Hz, 1H, arom.), 8.55
(dd, J¼8.6, 1.4 Hz, 1H, arom.), 8.15 (br s, 0.6H, Me2NH2), 7.89e7.83
(m, 2H, arom.), 6.83 (br s, 0.6H, Me2NH2), 5.54 (AB, J¼12.3 Hz, 4H,
CH2OV), 3.19e3.15 (m, 38.8H, N(CH2CH2CH2Me)4 and Me2NH2),
2.02 (q, J¼7.5 Hz, 2H, CH2Me), 1.62e1.54 (m, 37.6H,
N(CH2CH2CH2Me)4), 1.37e1.28 (m, 40.6H, N(CH2CH2CH2Me)4 and
CH2Me), 0.95e0.92 (m, 56.4H, N(CH2CH2CH2Me)4). 13C NMR
(100 MHz, DMSO-d6):
d
¼178.2 (C]O), 151.3 (CH arom.), 144.4 (C

B. Riflade et al. / Tetrahedron 69 (2013) 5772e5779
5779
ˇ
5. (a) Kurata, T.; Uehara, A.; Hayashi, Y.; Isobe, K. Inorg. Chem. 2005, 44,
2524e2530; (b) Villanneau, R.; Renaudineau, S.; Herson, P.; Boubekeur, K.;
Thouvenot, R.; Proust, A. Eur. J. Inorg. Chem. 2009, 479e488; (c) Angus-Dunne,
S.; Burns, R. C.; Craig, D. C.; Lawrance, G. A. Z. Anorg. Allg. Chem. 2010, 636,
727e734; (d) Hirano, T.; Uehara, K.; Kamata, K.; Mizuno, N. J. Am. Chem. Soc.
L.; Malacria, M.; Thorimbert, S.; Hasenknopf, B.; Lacote, E. Chem.dEur. J.
2012, 18, 12962e12965.
13. Li, J.; Huth, I.; Chamoreau, L.-M.; Hasenknopf, B.; Lacote, E.; Thorimbert, S.;
ˇ
Malacria, M. Angew. Chem., Int. Ed. 2009, 48, 2035e2038.
€
14. Oble
ˇ
, J.; Riflade, B.; Noel, A.; Malacria, M.; Thorimbert, S.; Hasenknopf, B.;
ꢀ
2012, 134, 6425e6433; (e) Duval, S.; Marrot, J.; Simonnet-Jegat, C.;
Lacote, E. Org. Lett. 2011, 13, 2990e5993.
ˇ
ꢀ
Mbomekalle, I. M.; Sokolov, M.; Cadot, E. Dalton Trans. 2012, 41, 3174e3184.
15. Riflade, B.; Oble, J.; Li, J.; Thorimbert, S.; Hasenknopf, B.; Lacote, E., submitted
for publication.
6. (a) Bi, L.-H.; Reicke, M.; Kortz, U.; Keita, B.; Nadjo, L.; Clark, R. J. Inorg. Chem.
2004, 43, 3915e3920; (b) Bi, L.-H.; Kortz, U.; Keita, B.; Nadjo, L.; Borrmann, H.
Inorg. Chem. 2004, 43, 8367e8372; (c) Bi, L.-H.; Kortz, U.; Keita, B.; Nadjo, L.;
Daniels, L. Eur. J. Inorg. Chem. 2005, 3034e3041; (d) Bi, L.-H.; Dickman, M. H.;
Kortz, U. CrystEngComm 2009, 11, 965e966; (e) Izarova, N. V.; Banerjee, A.;
Kortz, U. Inorg. Chem. 2011, 50, 10379e10386.
16. For the preparation of diol amides see: (a) Wybow, R. A. J.; Edwards, A. S.;
Stevenson, N. G.; Adams, H.; Johnstone, G.; Harrity, P. A. Tetrahedron 2004, 60,
8869e8880; (b) Adachi, K.; Kohara, N.; Nakao, N.; Arita, M.; Chiba, K.; Mishina, T.;
Sasaki, S.; Fujita, T. Bioorg. Med. Chem. Lett. 1995, 5, 853e856.
17. Zaitsev, V. D.; Shabashov, D.; Daugulis, O. J. Am. Chem. Soc. 2005, 127,
13154e13155.
7. Favette, S.; Hasenknopf, B.; Vaissermann, J.; Gouzerh, P.; Roux, C. Chem. Com-
mun. 2003, 2664e2665.
ꢀ
ꢀ
18. For recent references, see: (a) Julia-Hernandez, F.; Arcas, A.; Vicente, J.
Chem.dEur. J. 2012, 18, 7780e7786; (b) Sumimoto, M.; Kuroda, T.; Yokogawa,
D.; Yamamoto, H.; Hori, K. J. Organomet. Chem. 2012, 710, 26e35; (c)
Sundermann, A.; Uzan, O.; Martin, J. M. L. Chem.dEur. J. 2001, 7, 1703e1711
For a review, see; (d) Sehnal, P.; Taylor, R. J. K.; Fairlamb, I. J. S. Chem. Rev.
2010, 110, 824e889.
8. Bar-Nahum, I.; Cohen, H.; Neumann, R. Inorg. Chem. 2003, 42, 3677e3684.
9. (a) Berardi, S.; Carraro, M.; Iglesias, M.; Sartorel, A.; Scorrano, G.; Albrecht, M.;
Bonchio, M. Chem.dEur. J. 2010, 16, 10662e10666; (b) Santoni, M.-P.; Pal, A. K.;
Hanan, G. S.; Proust, A.; Hasenknopf, B. Inorg. Chem. 2011, 50, 6737e6745; (c)
ꢀ
Santoni, M.-P.; Pal, A. K.; Hanan, G. S.; Tang, M.-C.; Venne, K.; Furtos, A.; Menard-
ꢂ
Tremblay, P.; Malveau, C.; Hasenknopf, B. Chem. Commun. 2012, 200e202.
10. Ettedgui, J.; Neumann, R. J. Am. Chem. Soc. 2009, 131, 4e5.
11. Zhao, P.; Leng, Y.; Zhang, M.; Wang, J.; Wu, Y.; Huang, J. Chem. Commun. 2012,
19. (a) Selander, N.; Szabo, K. J. Chem. Rev. 2011, 11, 2048e2076; (b) Sommer, W. J.;
Yu, K.; Sears, J. S.; Ji, Y.; Zheng, X.; Davis, R. J.; Sherrill, C. D.; Jones, C. W.;
Weck, M. Organometallics 2005, 24, 4351e4361; (c) Nilsson, P.; Wendt, O. F. J.
Organomet. Chem. 2005, 690, 4197e4202; (d) Da Costa, R. C.; Jurisch, M.;
Gladysz, J. A. Inorg. Chim. Acta 2008, 361, 3205e3214; (e) Suijkerbuijk, B. M. J. M.;
Martinez, S. D. H.; van Koten, G.; Klein Gebbink, R. J. M. Organometallics 2008, 27,
534e542.
5721e5723.
12. (a) Boglio, C.; Lemiere, G.; Hasenknopf, B.; Thorimbert, S.; Lacote, E.;
Malacria, M. Angew. Chem., Int. Ed. 2006, 45, 3324e3327; (b) Boglio, C.;
ˇ
ꢂ
ˇ
ꢀ
Micoine, K.; Remy, P.; Hasenknopf, B.; Thorimbert, S.; Lacote, E.;
Malacria, M.; Alfonso, C.; Tabet, J.-C. Chem.dEur. J. 2007, 13, 5426e5432; (c)
Kikukawa, Y.; Yamaguchi, S.; Nakagawa, Y.; Uehara, K.; Uchida, S.; Yama-
€
€
€
20. Ahlrichs, R.; Bar, M.; Haser, M.; Horn, H.; Kolmel, C. Chem. Phys. Lett. 1989, 162,
165e169.
guchi, K.; Mizuno, N. J. Am. Chem. Soc. 2008, 130, 15872e1
Dupre, N.; Remy, P.; Micoine, K.; Boglio, C.; Thorimbert, S.; Lacote, E.; Ha-
ˇ
5878; (d)
21. Treutler, O.; Ahlrichs, R. J. Chem. Phys. 1995, 102, 346e354.
22. Weigend, F.; Haser, M.; Patzelt, H.; Ahlrichs, R. Chem. Phys. Lett. 1998, 294,
ꢀ
ꢀ
€
senknopf, B.; Malacria, M. Chem.dEur. J. 2010, 16, 7256e7264; (e)
143e152.
ꢀ
El Moll, H.; Nohra, B.; Mialane, P.; Marrot, J.;
Dˇ
upre, N.; Riflade, B.;
23. Boglˇ io, C.; Micoine, K.; Derat, E.; Thouvenot, R.; Hasenknopf, B.; Thorimbert, S.;
Malacria, M.; Thorimbert, S.; Hasenknopf, B.; Lacote, E.; Aparicio, P. A.;
Lopez, X.; Poblet, J. M.; Dolbecq, A. Chem.dEur. J. 2011, 17, 14129e14138; (f)
Lacote, E.; Malacria, M. J. Am. Chem. Soc. 2008, 130, 4553e4561.
24. Finke, R. G.; Rapko, B.; Saxton, R. J.; Domaille, P. J. J. Am. Chem. Soc. 1986, 108,
2947e2960.
25. (a) Malkov, A. V.; Hand, J. B.; Kocovsky, P. Chem. Commun. 2003, 1948e1949; (b)
Tse, M. K.; Jiao, H.; Anilkumar, G.; Bitterlich, B.; Gelalcha, F. G.; Beller, M. J. Org.
Chem. 2006, 691, 4419e4433.
ꢀ
Suzuki, K.; Sugawa, M.; Kikukawa, Y.; Kamata, K.; Yamaguchi, K.; Mizuno, N.
Inorg. Chem. 2012, 51, 6953e6961; (g) Absillis, G.; Parac-Vogt, T. N. Inorg.
Chem. 2012, 51, 9902e9910; (h) Vanhaecht, S.; Absillis, G.; Parac-Vogt, T. N.
ꢀ
Dalton Trans. 2012, 41, 10028e10034; (i) Dupre, N.; Brazel, C.; Fensterbank,