Di- and Tetranuclear Palladium(II) Complexes Containing C,N-Bidentate Furoylhydrazone for Suzuki–Miyaura Reactions

Article abstract of DOI:10.1002/ejoc.201700027

Furoylhydrazones of general formula 4-R–C₆H₄–CH=NNH–CO–2-C₄H₃O [R = H (HL1) and OCH₃ (HL2)] have been conveniently prepared from furan-2-carbohydrazide. The reaction of HL1 with Li₂[PdCl

Full text of DOI:10.1002/ejoc.201700027

A Journal of
Accepted Article
Title: Di- and Tetranuclear Palladium (II) Complexes Containing CN
Bidentate Furoylhydrazone for Suzuki-Miyaura Reaction
Authors: hengyu qian, tongyan zhang, liping song, shuyan yu, qi yuan,
luyan sun, dengfeng zhang, Zhigang Yin, and yongxia dai
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201700027
Link to VoR: http://dx.doi.org/10.1002/ejoc.201700027
Supported by

10.1002/ejoc.201700027
European Journal of Organic Chemistry
FULL PAPER
Di- and Tetranuclear Palladium (II) Complexes Containing CN
Bidentate Furoylhydrazone for Suzuki-Miyaura Reaction
Hengyu Qian[a][b][c], Tongyan Zhang[b], Liping Song[a][b][c]*, Shuyan Yu[b], Qi Yuan[b], Luyan Sun[b],
Dengfeng Zhang[b], Zhigang Yin[b]*, Yongxia Dai[b]
Dedication ((optional))
Abstract: Furoylhydrazones of general formula [R-4-C6H4-CH=NNH-
CO-2-C4H3O] with R=H (HL1) and R=OCH3 (HL2) were conveniently
prepared from furan-2-carbohydrazide. Reaction of HL1 with
Li2PdCl4 and CH3COONa provided the di-μ-chloro-bridged
cyclopalladated complex [Pd(C6H4-CH=N-NH-CO-2-C4H3O)(μ-Cl)]2
(1) via the aryl C-H bond activation, while for ligand HL2, the unusual
tetranuclear cluster [Pd(CH3O-C6H4-CH=N-NH-CO-2-C4H3O)(μ-Cl)]4
(2) was obtained. The crystal structures of 1, 2 showed a slightly
distorted-square-planar coordination geometry around the palladium
reactions remain woefully underdeveloped compared to the
metal-hydrazone complexes, but the hydrazone is limited to
N,N-dialkylhydrazone [9]
.
Based on state-of-the-art techniques, our groups are interested
in developing new palladated complexes as catalysts for the
construction of C-C bond. Previously, we examined
cyclopalladated ferrocene derivatives for Suzuki-Miyaura cross-
couplings [10] . In continuation of our ongoing research, we report
the synthesis and structural characterization of two new
ion to which the furoylhydrazone was attached in a bidentate fashion. cyclopalladated complexes containing furoylhydrazone ligand
As for the catalysts, these two palladium(II) complexes were able to
catalyze the Suzuki-Miyaura couplings of phenylboronic acid with
aryl halides to afford the desired biaryl derivatives in excellent yields
(up to 99.2%).
and their catalytic activity towards Suzuki-Miyaura cross-
coupling reaction of phenylboronic acid with aryl halides. In
contrast to the cyclopalladated aroylhydrazones complexes
featuring a C, N, O-tridentate ligand, the furoylhydrazone
present in these two palladium (II) complexes acts as bidentate
C, N-donor ligand in cyclometalation.
Introduction
Organopalladium complexes have been extensively surveyed
in the past few decades, and they exhibited numerous
applications in a wide range of areas including the synthesis of
natural products [1], pharmaceutical [2] and molecular materials [3]
.
Palladium complexes containing one metal-carbon bond in a
five- or six-membered ring, termed cyclopalladated complexes,
are one of the most popular class of organopalladium derivatives.
Since the first report of cyclopalladated azobenzene by Cope et
al. in 1965 [4], the knowledge and applicability of cyclopalladated
complexes have increased exponentially[5].
The hydrazones have considerable biological interest such as
antifungal and antitumor activities[6], and they can also act as
tridentate C, N, O-donor ligands for transition metals. For
example, metalation of aroylhydrazones has led to the formation
[7]
of 5,5- or 5,6-membered metallacycles (Scheme 1a)
.
Meanwhile, structurally characterized metallated complexes of
furoylhydrazones are rare (Scheme 1b)[8]. Additionally, these
metallated complexes as catalysts for C-C bond formation
Scheme 1. cyclopalladated hydrazone derivatives.
[a]
[b]
Hengyu Qian, Liping Song*
School of Materials Science and Engineering
Shanghai University
Shang-Da Road, Shanghai, 200444
E-mail: lpsong@shu.edu.cn
Hengyu Qian, Tongyan Zhang, Shuyan, Yu, Qi Yuan, , Luyan Sun,
Dengfeng Zhang, Zhigang Yin,* Yongxia Dai
Key Laboratory of Surface & Interface Science of Henan, School of
Material & Chemical Engineering
Zhengzhou University of Light Industry
Zhengzhou 450002, China
Results and Discussion
Synthesis of Ligands
As shown in Scheme 2, furoylhydrazones HL1, HL2 were
synthesized in 92.1% and 94.3% yields by condensation of
furan-2-carbohydrazide and the corresponding aromatic
aldehyde in methanol. The IR spectra of furoylhydrazones (HL1
and HL2) showed the strong bands at 3125 and 3120 cm-1,
respectively due to the amide N-H stretch. An intense band
observed at 1626 cm-1 (for HL1) and 1622 cm-1 (for HL2) was
E-mail: yinzg2014@126.com
Hengyu Qian, Liping Song*
Department of Chemistry
[c]
Shanghai University
Shang-Da Road, Shanghai, 200444
E-mail: lpsong@shu.edu.cn
Supporting information for this article is given via a link at the end of
the document.((Please delete this text if not appropriate))
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700027
European Journal of Organic Chemistry
FULL PAPER
assigned to the C=O stretch. The C=N stretch appeared as a
sharp band at 1570 and 1573 cm-1 for HL1 and HL2,
respectively. The 1H NMR spectra showed that the resonance of
the azomethine proton appeared as a singlet at 8.46 and 8.39
ppm, and the N-H proton resonated as a singlet at 11.86 and
11.72 ppm for HL1 and HL2, respectively. The signal
corresponding to the methoxyl proton of HL2 was observed at
3.81 ppm.
largest deviation from the mean plane being -0.0315Å at Pd1
(Pd1, C2, N1, Cl1, Cl2) and -0.0168 Å at C14 (Pd2, C14, N3,
Cl1, Cl2), respectively. The plane Pd1Cl1Pd2 formed a dihedral
angle of 7.5° with the plane Pd1Cl2Pd2. A long distance
between two palladium atoms (3.411 Å) demonstrated the lack
of Pd-Pd interactions [12]. The Pd-Cl2bridging bond lengths (Pd1-
Cl2, 2.489 Å; Pd2-Cl2, 2.466 Å), trans to carbon, were longer
than the Pd-Cl1bridging ones (Pd1-Cl1, 2.306 Å; Pd2-Cl1, 2.302 Å),
trans to nitrogen, this reflected the differing trans influence of the
aryl carbon and azomethine nitrogen [13]. The metallacycle was
co-planar with its attached aryl ring, making the dihedral angle of
0.8° and 1.2°, respectively.
Synthesis
and
characterization
of
cyclopalladated
complexes 1 and 2
Furoylhydrazones (HL1 and HL2) were treated with Li2PdCl4
and CH3COONa to provide the corresponding cyclopalladated
complexes in 71.2% and 65% yields as shown in Scheme 2 (1
and 2). These two palladated complexes are highly soluble in
dichloromethane, chloroform and acetone, and sparingly soluble
in alkanes. In the spectra of complexes
1 and 2 the
characteristic N-H and C=O stretching vibrations are also
observed at 3115, 3110 and 1613, 1608 cm-1, respectively. The
C=N absorptions are shifted to lower wave numbers by 17-20
cm-1 (1556 cm-1 for 1 and 1550 cm-1 for 2) compared to those of
the corresponding starting ligands, indicating the azomethine
nitrogen coordination to the metal ion [11]. From the 1H NMR data,
it is evident that the signal corresponding to the N-H proton in 1
and 2 appears at 11.18 and 11.05 ppm, respectively, indicating
[8b]
the carbonyl oxygen is not coordinated to the palladium ion
.
Four or three proton signals featuring in the region of 6.64-7.55
ppm are assigned to the aromatic protons present in the
respective
complexes.
These
results
suggest
that
Figure 1. Molecule drawing for 1. All H atoms have been omitted for clarity.
Selected bond lengths (Å) and angles (deg): Pd1-C2, 1.971(3); Pd1-N1,
2.022(3); Pd1-Cl1, 2.306(10); Pd1-Cl2, 2.489(10); Pd2-C14, 1.966(4); Pd2-N3,
2.033(3); Pd2-Cl1, 2.301(10); Pd2-Cl2, 2.466 (11); C2-Pd1-N1, 80.72(13); C2-
Pd1-Cl1, 94.50(11); Cl1-Pd1-Cl2, 88.16(4); Cl2-Pd1-N1, 96.55(8); Cl1-Pd2-Cl2,
88.82(3); Cl1-Pd2-C14, 94.02(11); C14-Pd2-N3, 80.90(14); N3-Pd2-Cl2,
96.27(9).
furoylhydrazones do not act as tridentate C, N, O-donor ligand,
but C, N-donor type instead.
As depicted in Figure 2, the molecular structure of 2 showed an
unusual [Pd4Cl4(HL2)4] tetrameric structure, in which each
palladium atom appeared to be slightly distorted square-planar
geometry defined by aryl carbon, azomethine nitrogen and two
chloride atoms. Additionally, the core of the molecule consisted
of a Pd4Cl4 fragment of alternating Pd and Cl atoms. These
findings were different from other palladium complexes in which
hydrazones acted as tridentate C, N, O-donor ligands. The Pd-
Cl (Pd1-Cl2=2.461 Å, Pd2-Cl2A=2.458) bond distances were
longer than the other corresponding values (Pd1-Cl1, 2.317 Å,
Pd2-Cl1, 2.325 Å), consistent with those found in related
complexes [10a, 14], indicating the strong trans influence of Pd-
Csp2 bond. The Pd-C bond lengths [Pd1-C1, 2.018 Å; Pd2-C19,
2.002 Å] were within the range reported in the literature [15].The
Pd-N bond lengths (Pd1-N1, 2.034 Å; Pd2-N3, 2.029 Å) were
appreciably longer than the sum of the covalent radii for
palladium and nitrogen (2.01 Å) [16], revealing the trans influence
of the chloride atom.
Scheme 2. Synthesis of cyclopalladated complexes 1 and 2.
Molecular Structure of cyclopalladated complexes 1 and 2
To obtain more perceivable knowledge of the coordination
mode of hydrazone ligands in the synthesized complexes, single
crystals of complexes 1 and 2 suitable for X-ray analysis were
obtained by slow evaporation from dichloromethane/methanol.
As shown in Figure 1, the X-ray crystal structure analysis of 1
revealed that the hydrazone ligand was bonded to the di-μ-
chloro-bridged unit via the aryl carbon and azomethine nitrogen,
forming a five -membered chelate ring. The palladium(II) center
was in a slightly distorted square-planar environment, with the
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700027
European Journal of Organic Chemistry
FULL PAPER
Table 1. Suzuki-Miyaura Reactions: Effect of Reaction Parameters[a]
entry
variation from the standard conditions
Yield(%)
1
none
97.3
91.3
65.6
55.1
41.2
80.2
94.2
96.2
95.6
43.2
75.1
72.8
97.8
2
Cs2CO3 instead of K3PO4∙7H2O
K2CO3 instead of K3PO4∙7H2O
KOH instead of K3PO4∙7H2O
KF∙2H2O instead of K3PO4∙7H2O
Et3N instead of K3PO4∙7H2O
toluene at 50°C
3
4
5
6
Figure 2. Molecule drawing for 2. All H atoms have been omitted for clarity.
Selected bond lengths (Å) and angles (deg): Pd1-C1, 2.018(7); Pd1-N1,
2.034(7); Pd1-Cl1, 2.317(2); Pd1-Cl2, 2.461(2); Pd2-Cl1, 2.325(2); Pd2-Cl2A,
2.458(10); Pd2-N3, 2.029(10); C1-Pd1-N1, 80.7(3); C1-Pd1-Cl1, 93.6(3); Cl1-
Pd1-Cl2, 93.01(8); Cl2-Pd1-N1, 92.3(2); C19-Pd2-N3, 80.6(3); C19-Pd2-Cl1,
95.0(3); Cl1-Pd2-Cl2A, 91.7(3); Cl2A-Pd2-N3, 92.2(8).
7
8
toluene at 80°C
9
toluene at 110°C
10
11
12
13
THF at 60°C, instead of toluene
dioxane at 60°C, instead of toluene
methanol at 60°C, instead of toluene
3h instead of 2h
Application in the Suzuki-Miyaura Reaction
The cross-coupling of organoboron species and organo
halides, known as the Suzuki-Miyaura reaction, is one of the
[a] Isolated yields (average of two runs).
most powerful methods for carbon-carbon formation, especially
[17]
for the synthesis of natural products and auxiliary ligands
.
Under our standard conditions, the coupling of phenylboronic
acid with a range of aryl bromides produced the desired biaryl
derivatives in excellent yield (Table 2). Functional groups such
as hydroxyl (entry 1), ether (entries 2-3), alkyl (entry 4), cyano
(entries 5-8), carbonyl (entries 9-10) and nitro (entries 11-12)
were also tolerated. Moreover, aryl bromides bearing electron-
withdrawing substituents proceeded almost quantitatively yields
when the catalyst loading was lowered (entries 6, 8, 10, 12).
Since its discovery in 1979 [18], thousands of palladium catalysts
have been used to perform this coupling reaction. Despite
considerable effort in this area, the development of highly
efficient catalytic systems with wide substrate tolerance is still a
challenging problem. Thus, we wonder whether the present
tetranuclear palladium cluster 2 can proceed better in the
coupling reaction of bromobenzene with phenylboronic acid.
After extensive studies, we determined that compound 2
(0.02%) and K3PO4∙7H2O (1 equiv) in toluene at 60°C were
optimal for bromobenzene, providing the coupling product in a
97.3% yield. (Table 1, entry 1.) If the cross-coupling was
conducted at 50, 80 or 110°C, a little erosion in yield was
observed (entries 7-9). And replacement of toluene with THF
was deleterious (entry 10). Other solvents, dioxane and
methanol, did not yield better results (entries 11-12).
Table 2. Cross-Couplings of Aryl Bromides with Phenylboronic Acid[a]
.
Yield (%)
entry
Ar
catalyst 1
89.2
catalyst 2
92.4
1
2
88.9
93.1
3
86.2
90.3
4
5
91.3
97.2
93.2
99.2
6
7
96.1
95.3
98.8
96.8
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700027
European Journal of Organic Chemistry
FULL PAPER
C,N-bidentate coordination of hydrazone ligands, as opposed to
the palladium complexes obtained from tridentate [CNO]
aroylhydrazone ligands. In addition, these complexes have been
utilized as the catalysts for the Suzuki-Miyaura reaction of aryl
halides with phenylboronic acid, giving the biaryl segments in
excellent yields under mild reaction conditions. Further studies
are in progress centered on the regioselectivity of metalation in
furoylhydrazone of aromatic aldehydes and their applications in
cross-coupling reactions.
8
93.1
95.6
9
98.4
95.2
97.2
99.2
96.3
98.9
10
11
Experimental Section
12
96.5
97.2
General Procedures. Melting points were measured on an microscopic
apparatus and were uncorrected. Infrared spectra were recorded on a
Bruker Vector 22 spectrophotometer, Elemental analyses were carried
out with a VARIO ELIII microanalyzer. NMR spectra were recorded on a
Bruker DPX 400 spectrometer, using CDCl3 or (CD3)2SO as solvent and
TMS as an internal reference standard. Solvents were dried and distilled
under nitrogen prior to use. PdCl2 was purchased from Acros and used
without purification.
[a] Reaction conditions: see Table 1 entry 1. [b] Catalyst: 0.002%.
The scope of aryl chloride coupling parter was also
investigated (Table 3). Aryl chlorides with ether, nitro and
carbonyl functionalities were able to generate good yields
when coupling with PhB(OH)2 (entries 1-8). In the case of
the acetyl-substituted substrate (entry 8), excellent yield
was obtained by increasing the catalyst loading to 0.1%.
Synthesis of the ligands HL1 and HL2. A mixture of furan-2-
carbohydrazide (0.252 g,
2 mmol), the aryl aldehyde (2 mmol)
[benzaldehyde (0.212 g) or p-methoxybenzaldehyde (0.272 g)] and 10
mL of methanol was boiled under reflux for 2h. The solid was collected
by filtration, washed with cold methanol and dried in air.
Table 3. Cross-Couplings of Aryl Chlorides with Phenylboronic Acid [a]
.
N'-benzylidenefuran-2-carbohydrazide (HL1): white solid (0.401 g,
93.7%). m.p. 223-225°C; 1H NMR (400Hz, d6-DMSO, 25°C, TMS): δ 6.71,
7.30, 7.96 (3H, furyl-H), 7.44-7.49 (3H, m, Ph-H), 7.71-7.73 (2H, m, Ph-
H), 8.46 (1H, s, CHNNH), 11.86 (1H, s, CHNNH); 13C NMR: δ 112.3,
115.2, 127.3, 129.1, 130.3, 134.4, 146.1, 146.8, 148.1, 154.4; IR (KBr
pellet): 3125, 2857, 1626 (νc=o) and 1570 (νc=N) cm-1; elemental analysis:
calcd.(%) for C12H10N2O2 (214): C 67.29, H 4.67, N 13.08; Found: C
67.51, H 4.42, N 13.21.
Yield(%)
entry
1
Ar
catalyst 1
67.5
catalyst 2
71.3
N'-(4-methoxybenzylidene)furan-2-carbohydrazide (HL2): white
1
solid (0.460 g, 94.3%); m.p. 220°C decomp; H NMR (400Hz, d6-DMSO,
25°C, TMS): δ 3.81 (3H, s, CH3), 6.98, 7.28, 7.93 (3H, furyl-H) 7.01-7.03
(2H, d, J = 8.7 Hz, Ar-H), 7.65-7.67 (2H, d, J = 8.7 Hz, Ar-H), 8.39 (1H, s,
CHNNH), 11.72 (1H, s, CHNNH); 13C NMR: δ 55.5, 112.2, 114.5, 114.8,
127, 128.9, 145.9, 146.9, 147.9, 154.2, 161; IR (KBr pellet): 3120, 2851,
1622 (νc=o) and 1573 (νc=N) cm-1; elemental analysis: calcd.(%) for
C13H12N2O3 (244): C 63.93, H 4.92, N 11.47; Found: C 63.71, H 4.74, N
11.75.
2
82.1
88.5
3
4
5
60.2
78.4
78.1
64.1
81.2
80.2
Synthesis of the Palladium (II) complexes 1 and 2. A solution of the
hydrazone ligands HL1 and HL2 (1 mmol), Li2PdCl4 (1 mmol, 10mL), and
CH3COONa (0.082g, 1mmol) in dry methanol was stirred for 20h at room
temperature. The resulting precipitate was filtered and purified by column
chromatography (CH2Cl2/CH3OH = 25:1)
6
7
87.5
74.2
90.2
79.3
[Pd(C6H4-CH=N-NH-CO-C4H3O)(μ-Cl)]2 red solid (0.253 g, 71.2%);
m.p.: 210°C decomp; 1H NMR (400Hz, CDCl3, 25°C, TMS): δ 6.74, 7.34,
7.99 (3H, furyl-H), 7.03-7.20 (2H, m, Ph-H), 7.50-7.55 (2H, m, Ph-H),
8.83-8.84 (1H, CHNNH), 11.18 (1H, s, CHNNH); 13C NMR: δ 112.5,
116.1, 124.3, 125.9, 128.5, 129.1, 131.4, 134.9, 145.1, 146.6, 155.6,
170.6; IR (KBr pellet): 3115, 2840, 1613 (νc=o) and 1556 (νc=N) cm-1.
elemental analysis: calcd.(%) for C24H18Cl2N4O4Pd2 (695.8): C 40.57, H
2.53, N 7.89; Found: C 40.42, H 2.48, N 7.93.
8
86.8
91.2
[Pd(CH3O-C6H3-CH=N-NH-CO-C4H3O)(μ-Cl)]4 red solid (0.250 g,
65%); m.p.: 215°C decomp; 1H NMR (400Hz, CDCl3, 25°C, TMS): δ 6.75,
7.32, 7.98 (3H, furyl-H), 6.64-6.65, 6.76-6.78 (1H, m, Ph-H), 7.38-7.39
(1H, m, Ph-H), 7.55 (1H, s, Ph-H), 8.63-8.88 (1H, m, CHNNH), 11.05 (1H,
s, CHNNH); 13C NMR: δ 109.9, 110.7, 112.6, 115.9, 116.4, 118.6, 120.9,
130.4, 131.6, 136.3, 145.5, 146.6, 155.2, 158.3, 159.2, 160.6, 172.1; IR
(KBr pellet): 3110, 2842, 1608 (νc=o) and 1550 (νc=N) cm-1; elemental
analysis: calcd.(%) for [C13H11ClN2O3Pd]4 (1539.6): C 40.53, H 2.86, N
7.27; Found: C 40.75, H 2.58, N 7.31.
[a] Reaction conditions: see Table 1 entry 1. [b] Catalyst: 0.1%.
Conclusions
In summary, two cyclopalladated complexes [Pd(HL1)Cl]2
1
General procedure for Suzuki-Miyaura cross-coupling reaction:
Aryl bromide (1.0 mmol), phenylboronic acid (1.2 mmol), K3PO4·7H2O
(1.0 mmol), and catalyst (0.02%) were dissolved in 6 mL toluene and
stirred at 60°C for 2h. The reaction mixture was quenched with water and
and [Pd(HL2)Cl]4 2 based on furoylhydrazone ligands have been
synthesized and characterized. X-ray diffraction data of these
two complexes confirm that the palladium (II) ion satisfied by
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700027
European Journal of Organic Chemistry
FULL PAPER
extracted with CH2Cl2. After the removal of the solvent, the residue was
purified by column chromatography.
Chem., 2013, 66, 218-226; c) Qian., H. Y., Cui, X. L., Tang, M. S., Liu,
C. H, Liu, C, Wu, Y. J., New J. Chem., 2009, 33, 668-674.
[11] I. Omae, Coord. Chem. Rev. 2004, 248, 995-1023.
[12] T. Murahashi, H. Kurosawa, Coord. Chem. Rev. 2002, 231, 207-228.
[13] C. Arlen, M. Pfeffer, O. Bars, D. Grandjean, J. Chem. Soc., Dalton
Trans. 1983, 1535-1544.
X-ray Crystallographic Studies of Cyclopalladated Complexes 1
and 2: Single crystal of cyclopalladated complexes 1 and 2 suitable for
X-ray diffraction analysis was obtained from CH2Cl2/CH3OH solution. X-
ray single-crystal diffraction data for complexes 1 and 2 were collected
on a Oxford Xcalibur, Gemini, Eos CCD diffractometer at 291(2) K with
Mo-Kα radiation ( = 0.71073 Å) by  scan mode. The structure was
solved by direct methods using the SHELXS program of the SHELXTL
package and refined by full-matrix least-squares methods with
SHELXL.[19] CCDC Nos. 1495796 and 1495797 contain the
supplementary crystallographic data for complexes 1 and 2. This material
can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK;
fax: (+44) 1223-336-033; or E-mail: deposit@ccdc.cam.ac.uk.
[14] M. López-Torres, P. Juanatey, J. J. Fernández, A. Fernández, A.
Suárez, R. Mosteiro, J. M. Ortigueira, J. M. Vila, Organometallics, 2002,
21, 3628-3636.
[15] Zhao, G., Xue, F., Zhang, Z. Y., T. C. W. Mak, Organometallics, 1997,
16, 4023-4026.
[16] L. Pauling, The Nature of the Chemical Bond, Cornell University Press,
New York, 3rd edn., 1960.
[17] a) Zhang, D., Wang, Q. R., Coord. Chem. Rev. 2015, 286, 1-16; b) Xu,
G. Q., Fu, W. Z., Liu, G. D., C. H. Senanayake, Tang, W. J., J. Am.
Chem. Soc. 2014, 136, 570-573; c) Han, F. S., Chem. Soc. Rev. 2013,
42, 5270-5298; d) N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457-
2483.
Acknowledgements
[18] N. Miyaura, K. Yamada, A. Suzuki, Tetrahedron Lett. 1979, 36, 3437-
3440.
The work is supported by National Natural Science
Foundation of China (No. 21406209 and 21602207) and
National Training Programs of Innovation and Entrepreneurship
for Undergraduates.
[19] G. M. Sheldrick, SHELXL-97, Program for the Refinement of Crystal
Structures 1997 (University of Göttingen: Germany).
Keywords: furoylhydrazone • tetranuclear • palladium complex •
catalyze • Suzuki-Miyaura coupling
[1]
a) M. Bera, S. K. Sahoo, D. Maiti, Acs Catal., 2016, 6, 3575-3579; b) Y.
Minami, T. Hiyama, Acc. Chem. Res., 2016, 49, 67-77; c) C. Deraedt, D.
Astruc, Acc. Chem. Res., 2014, 47, 494-503; d) E. V. Vinogradova, C.
Zhang, A. M. Spokoyny, B. L. Pentelute, S. L. Buchwald, Nature, 2015,
526, 687-691.
[2]
a) M. Nakajima, S. Arai, A. Nishida, Angew. Chem. 2016, 128, 3534-
3537; Angew. Chem., Int. Ed. 2016, 55, 3473-3476; b) L. S. Tsutsumi,
D. Gündisch, D. Q. Sun, Curr. Top. Med. Chem. 2016, 16, 1290-1313;
c) J. J. Topczewski, P. J. Cabrera, N. I. Saper, M. S. Sanford, Nature,
2016, 531, 220-224; d) V. V. Grushin, Acc. Chem. Res., 2010, 43, 160-
171.
[3]
a) Xie, S. F., Xu, Q. C., Huang, X. Q., ChemCatChem, 2016, 8, 480-
485; b) L. G. Mercier, M. Leclerc, Acc. Chem. Res., 2013, 46, 1597-
1605; c) C. L. Allen, J. M. J. Williams, Chem. Soc. Rev., 2011, 40,
3405-3415.
[4]
[5]
A. C. Cope, R. W. Siekman, J. Am. Chem. Soc., 1965, 87, 3272-3273.
a) Xu, J. W., Zhang, Z. Z., Rao, W. H., Shi, B. F., J. Am. Chem. Soc.,
2016, 138, 10750-10753; b) V. V. Dunina, O. N. Gorunova, P. A. Zykov,
K. A. Kochetkov, Russ. Chem. Rev., 2011, 80, 51-74; c) J. Dupont, C.
S. Consorti, J. Spencer, Chem. Rev., 2005, 105, 2527-2572.
a) P. Krishnamoorthy, P. Sathyadevi, A. H. Cowley, R. R. Butorac, N.
Dharmaraj, Eur. J. Med. Chem., 2011, 46, 3376-3387; b) C. Loncle, J.
M. Brunel, N. Vidal, M. Dherbomez, Y. Letourneux, Eur. J. Med. Chem.,
2004, 39, 1067-1071; c) M. Alagesan, N. S. P. Bhuvanesh, N.
Dharmaraj, Dalton Trans., 2013, 42, 7210-7223.
[6]
[7]
a) A. S. EI-TabI, F. A. EI-Saied, A. N. AI-Hakimi, J. Coord. Chem., 2008,
61, 2380-2401; b) G. N. Babu, S. Pal, J. Organomet. Chem. 2016, 805,
19-26; c) A. R. B. Rao, S. Pal, J. Organomet. Chem. 2013, 731, 67-72;
d) S. Das, S. Pal, J. Organomet. Chem. 2004, 689, 352-360.
a) V. Arumugam, W. Kaminsky, N. S. P. Bhuvanesh, D. Nallasamy,
RSC Adv., 2015, 5, 59428-59436; b) V. Arumugam, W. Kaminsky, D.
Nallasamy, Green Chem., 2016, 18, 3295-3301.
[8]
[9]
a) T. Mino, T. Koizumi, S. Suzuki, K. Hirai, K. Kajiwara, M. Sakamoto, T.
Fujita, Eur. J. Org. Chem., 2012, 678-680; b) R. Lazny, A. Nodzewska,
Chem. Rev., 2010, 110, 1386-1434; c) T. Mino, Y. Shirae, Y. Sasai, M.
Sakamoto, T. Fujita, J. Org. Chem. 2006, 71, 6834-6839; d) T. Mino, Y.
Shirae, M. Sakamoto, T. Fujita, J. Org. Chem. 2005, 70, 2191-2194.
[10] a) Qian, H. Y., Yin, Z. G., Zhang, T. Y., Yan, S. H., Wang, Q. L. Zhang,
C. X., Organometallics, 2014, 33, 6241-6246; b) Yin, Z. G., Qian, H. Y.,
Wang, Q. L., Dong, H. C., Yan, S. H., Zhang, C. X., Li, J. H., Aus. J.
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700027
European Journal of Organic Chemistry
FULL PAPER
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700027
European Journal of Organic Chemistry
FULL PAPER
Entry for the Table of Contents (Please choose one layout)
Layout 1:
FULL PAPER
Palladation of N'-benzylidenefuran-2-
carbohydrazide gave the di-μ-chloro-
bridged palladium(II) complex, while
metalation of N'-(4-methylbenzyLide-
ne)furan-2-carbohydrazide afforded
the unusual tetranuclear complex 2. In
addition, these palladium (II)
complexes exhibited high efficiency in
the Suzuki-Miyaura coupling reaction
of phenylboronic acid with aryl halides
using low catalyst loading 0.002
mol%.
Hengyu Qianabc, Tongyan Zhangb, Liping
Songac*, Shuyan, Yub, Qi Yuanb, Luyan
Sunb, Dengfeng Zhangb, Zhigang Yinb*,
Yongxia Daib,
Page No. – Page No.
Di- and Tetranuclear Palladium (II)
Complexes Containing CN Bidentate
Furoylhydrazone for Suzuki-Miyaura
Reaction
This article is protected by copyright. All rights reserved.