Palladium(II) thiosemicarbazone-catalyzed Suzuki-Miyaura cross-coupling reactions of aryl halides

Article abstract of DOI:10.1016/j.inoche.2013.03.032

A new air-and moisture-stable palladium(II) complex bearing pyridoxal thiosemicarbazone ligand has been synthesized. The synthesized complex was characterized by analytical and spectral methods. The molecular structure of the complex was confirmed by X-ray diffraction method. The palladium(II) complex was used as potential catalyst for Suzuki-Miyaura coupling reaction of several aryl halides under optimized conditions.

Full text of DOI:10.1016/j.inoche.2013.03.032

Inorganic Chemistry Communications 33 (2013) 33–37
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Palladium(II) thiosemicarbazone-catalyzed Suzuki–Miyaura
cross-coupling reactions of aryl halides
a
a,
b
a
Devaraj Pandiarajan , Rengan Ramesh ⁎, Yu Liu , Rajamanickam Suresh
a
School of Chemistry, Bharathidasan University, Tiruchirappalli-620 024, India
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
A new air- and moisture-stable palladium(II) complex bearing pyridoxal thiosemicarbazone ligand has been
synthesized. The synthesized complex was characterized by analytical and spectral methods. The molecular
structure of the complex was confirmed by X-ray diffraction method. The palladium(II) complex was used as
potential catalyst for Suzuki–Miyaura coupling reaction of several aryl halides under optimized conditions.
Received 3 January 2013
Accepted 25 March 2013
Available online 10 April 2013
©
2013 Elsevier B.V. All rights reserved.
Keywords:
Palladium(II) pyridoxal thiosemicarbazone
Crystal structure
Suzuki–Miyaura cross-coupling reaction
Palladium-catalyzed Suzuki–Miyaura coupling reaction is one of
the most efficient methods for the synthesis [1–3] of biaryl and alkene
derivatives that are structural components of numerous natural
products, agrochemicals, pharmaceuticals, and polymers [4–8]. In re-
cent years, this reaction has been successfully applied for the synthesis
of natural products [9–11], drugs [12–14] and conducting polymers
thiosemicarbazone in solution adopts an equilibrium mixture of thione
and thiol tautomers. In this regard, our attention is directed to the
design of pyridoxal thiosemicarbazone, which can adopt the above
mentioned forms.
As per the literature review palladacycles are proved to be a most
developed and extensively studied catalysts [25,26] because of their
structural versatility and easy synthetic accessibility. Among them,
phosphapalladacycles [27–30] and NHC [31,32] are able to catalyze
the Suzuki–Miyaura cross-couplings of aryl bromides and chlorides
with phenylboronic acids in excellent yields. A number of palladium
complexes of pincer-type ligands have been found to be efficient
catalysts for C\C bond formation reactions [33–36]. In general
thiosemicarbazone metal complexes are prolific and there are few re-
ports on their use in catalysis. One of the first reports of their catalytic
application was published in 1998 [37]. Pelagatti and his co-workers
described chemo selective homogeneous hydrogenation reactions
using tridentate [N,N,S]thiosemicarbazone palladium(II) complexes
[37]. The palladium complexes with S- or Se-containing Schiff base
ligands are developed as efficient catalysts for the Suzuki–Miyaura
cross-coupling reaction [38]. J. Mao et al. developed thiosemicarbazone
salicylaldiminatopalladium(II)-catalyzedMizoroki–Heckreactions[39].
It is worth mentioning that there are a limited number of articles that
are published related to the palladium(II) thiosemicarbazone catalyzed
Suzuki–Miyaura reaction [40–42].
[15,16]. Although several other methods (e.g. Kharash coupling, Negishi
coupling, Stille coupling, Himaya coupling, Liebeskind–Srogl coupling
and Kumuda coupling) are available for this purpose, the SM cross-
coupling reaction which produces biaryls has proven to be the most
popular in recent times. Moreover, the palladium assisted method of-
fers many advantages over other transition-metal catalyzed reactions,
such as commercial availability of a large panel of boronic acid deriva-
tives, easy handling, easy removal of boron residues, and high func-
tional group tolerance, explaining the increasing interest not only in
academic research but also in the industrial scientific community
[17–21]. Even though a significant progress has been developed, there
is a continuous demand for alternative protocol to achieve, new, easy
to prepare, stable ligands, and efficient catalytic systems.
Generally thiosemicarbazone is a class of ligands that exhibits a
broad range of stereochemistries in complexation with transition
metal ions. A variety of functional groups have been attached to the
thiosemicarbazone moiety in order to modify the physical, chemical
and/or biological properties of the resulting metal complexes [22]. It
is well known that depending on the appropriate coordination atoms
In view of the growing interest on the catalytic activities of
palladium(II) complexes as efficient catalysts in the cross-coupling
reactions [43–45], we report here the easy synthesis of new palladium(II)
pyridoxal thiosemicarbazone complex containing triphenylphosphine.
The pyridoxal thiosemicarbazone ligand was prepared according to a
procedure described in the literature [46,47]. The new palladium cata-
(
O, N, and X, where X = N, O, S, and Se), the ligand can bind to the
metal ions either in its neutral or anionic form [23,24]. Moreover,
⁎
Corresponding author. Tel.: +91 431 2407053; fax: +91 431 2407045, +91 431
407020.
E-mail address: ramesh_bdu@yahoo.com (R. Ramesh).
2
1
3
lyst precursor [Pd(PPh )(L)] was synthesized by reacting pyridoxal
387-7003/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.inoche.2013.03.032

34
D. Pandiarajan et al. / Inorganic Chemistry Communications 33 (2013) 33–37
HO
N
HO
H
H
H
H
H
N
N
N
N
[
PdCl (PPh ) ]
2 3 2
N
N
S
N
S
MeOH/TEA
O
Pd
PPh3
OH
H2L
CH3
CH3
Scheme 1. Synthesis of palladium(II) pyridoxal thiosemicarbazones.
thiosemicarbazone ligand with one equivalent of PdCl
2
(PPh
3
)
2
and
Single crystal suitable for X-ray diffraction studies were grown by
slow evaporation of dichloromethane/methanol solvent at room tem-
perature. The crystal structure of the complex has been elucidated by
X-ray diffraction with selected bond distances and angles. The molec-
ular structure of the complex is depicted in Fig. 1, and selected crys-
tallographic data are summarized in the Supporting information.
In the crystal structure the ligand is coordinated to the palladium
metal via the phenolic oxygen, imine nitrogen and thiolate sulfur
atom in a square-planar geometry, forming five- and six-membered
chelate rings with the metal center. The fourth coordination site is occu-
pied by a triphenylphosphine ligand and is trans to imine nitrogen. The
bite angles around Pd(II) ion are N3–Pd1–S1 = 83.4(3)°; N3–Pd1–
O2 = 93.4(4)°; O2–Pd1–S1 = 176.0(3)°; S1–Pd1–P1 = 97.92(12)°,
and bond length of 1.740(13) Å for C(7)–S(1), 1.324(14) Å for C(8)–
N(3). The bond lengths and bond angles are very similar to those
observed in other palladium(II) complexes [48].
triethylamine in methanol under reflux for 3 h (Scheme 1). The synthe-
sized palladium(II) complex was highly soluble in common solvents
such as chloroform and dichloromethane. The analytical data (C, H, N
and S; Calcd: C, 58.03; H, 4.28; N, 8.20; S, 4.69; Found: C, 58.12; H,
4
.32; N, 8.16; S, 4.58) are in good agreement with the compositions
proposed for the complex.
The νC=S and νN–H bands of the ligand disappeared upon com-
plexation with palladium and the appearance of a new band in the
−
1
region 815 cm
is assigned to the ν(C–S) mode. In addition, the com-
−
1
−1
plex shows new bands near 1668 cm
and 1316 cm
confirm the
coordination of imine nitrogen (νC=N) and phenolic oxygen (νC–O) to
the palladium respectively. The electronic spectrum of the palladium(II)
pyridoxal thiosemicarbazone shows an intense ligand-centered (LC)
π → π* transition at 248 nm, and moderately intense metal to ligand
charge-transfer (MLCT) transition in the visible region 435 nm.
1
H NMR spectrum of the complex shows a multiplet in the range
Further, palladium-catalyzed protocol for Suzuki–Miyaura cross-
coupling reactions with the synthesized complex has been carried out.
The initial screen on solvents was performed using the palladium(II)
pyridoxal thiosemicarbazone complex as catalyst (Table 1, entries
1–6). In the solvents variation experiment, we have chosen the
1:300 ratio of 4-bromoacetophenone with phenylboronic acid in the
7
.5–8.4 ppm assigned to aromatic protons of the phenyl group of
triphenylphosphine and the ligand aromatic protons. The methylene
and methyl proton of the pyridoxal moiety of the ligand appear at δ
4
.76 and δ 2.60 ppm respectively. The 31P-{H}NMR spectrum of the
complex showed a sharp peak at δ 25.744 ppm which confirms the
presence of one triphenylphosphine group in the complex (Fig. 1, 2
Supporting information). ESI-MS experiment supported the forma-
tion of palladium(II) pyridoxal thiosemicarbazone complex by the
appearance of prominent peak (m/e = 683.27) corresponding to
2 3
presence of various solvents and K CO base. Suzuki–Miyaura reaction
with water as solvent shows no noticeable conversions even after
24 h. Among the seven different solvents that were tested in our solvent
screening experiment, the polar solvents such as methanol and ethanol
were the most effective solvents for the coupling reaction (entries 2, 3;
+
the M mass of the complex.
9
2%, 99%). In the case of DMF solvent the conversion is relatively low.
Other solvents such as dioxane and THF afforded very low coupled
product conversions (entries 5,6; 56%, 42%).
In order to select the suitable base for our investigation, we have
performed the effects of various bases by using the coupling of
O1
4
-bromoacetophenone with phenyl boronic acid as a test case. The
base variation experiments were performed using 1:300 ratio of the
catalyst and the substrate in 10 mL ethanol with different bases.
C8
N2
N3
C7
N1
N4
C10
O2
Table 1
Effect of solvents.
a
Pd1
S1
P1
Entry
Solvents
Time (h)
Conversion (%)b
1
2
3
3
4
5
6
H
2
O
24
3
3
3
3
NRc
92
>99
89
81
56
Methanol
Ethanol
DMF
Toluene
Dioxane
THF
3
3
42
3
Fig. 1. Molecular structure of [Pd(PPh )L] showing the 50% probability level. All hydrogen
a
atoms are omitted for clarity. Selected bond lengths [Å]: Pd(1)–N(3) 2.006(10), Pd(1)–
O(2) 2.014(8), Pd(1)–S(1) 2.242(3), Pd(1)–P(1) 2.282(3), S(1)–C(7) 1.740(13), N(2)–
N(3) 1.403(13); bond angles [°]:N(3)–Pd(1)–O(2) 93.4(4), N(3)–Pd(1)–S(1) 83.4(3),
O(2)–Pd(1)–S(1) 176.0(3), N(3)–Pd(1)–P(1) 174.4(3), O(2)–Pd(1)–P(1) 85.5(3), S(1)–
Pd(1)–P(1) 97.92(12).
Reaction conditions: 4-Bromoacetophenone (0.3 mmol), phenylboronic acid
(0.45 mmol), catalyst (0.001 mmol), base (1.5 mmol) and solvent (5 mL).
b
1
Conversion to the coupled product was determined by H NMR spectroscopy based
on 4-bromoacetophenone; average of two runs.
c
No reaction.

D. Pandiarajan et al. / Inorganic Chemistry Communications 33 (2013) 33–37
35
Table 2
Effect of bases.
Table 4
a
a
Suzuki–Miyaura cross-coupling of aryl halides.
Entry Aryl bromide
1
Boronicacid
Conversion (%)b TONe
92
460
Sl.No
Base
Time (h)
Conversion (%)b
2
3
95
475
495
1
2
3
4
5
NaOH
3
3
3
3
3
73
68
94
>99
38
Cs
Na
CO
2
CO
3
>99
2
CO
3
K
2
3
t
KOBu
4
5
94
470
495
a
Reaction conditions: 4-Bromoacetophenone (0.3 mmol), phenylboronic acid
(
0.45 mmol), catalyst (0.001 mmol) and base (1.5 mmol), solvent (5 mL).
>99
b
Conversion to the coupled product was determined by 1H NMR spectroscopy based
on 4-bromoacetophenone; average of two runs.
6
7
8
>99
97
495
485
401
First the reaction was conducted without any base and no reaction
was observed even after 24 h. The addition of inorganic bases, like
NaOH, Cs
8% and 94% respectively (Table 2; entries 1–3). After screening a va-
riety of bases K CO was found to give the best conversion (Table 2).
According to a report by Bele et al. [49], K CO is an effective base for
2 3 2 3
CO and Na CO shows a moderate conversion of 73%,
80
6
2
3
2
3
86
430
t
9
many palladium-catalyzed coupling reactions. In the case of KOBu
we observed the poor conversion of 38%.
Low catalyst loading tests were performed to determine the cata-
lytic efficiency of the catalyst in the presence of K CO and ethanol as
2 3
solvent (Table 3). In the reaction optimization, we started the C/S
ratios of 1:100, 1:300, and 1:500 and the reaction proceeds with
excellent conversions. When increasing the C/S ratio to 1:1000 and
:3000 the reaction still proceeds with moderate conversions. Thus,
it was concluded that a catalyst:substrate ratio of 1:500 is the best
compromise between optimum reaction rate and C/S ratio.
1
1
1
0
1
2
78
93
92
390
465
460
1
Once we had thoroughly optimized the reaction conditions, the
Suzuki–Miyaura coupling of 1:1000 ratio of complex and the aryl
halides with aryl boronic acids bearing different substituents was car-
ried out and the results are summarized in Table 4. The coupling reac-
tion of 4-bromoacetophenone with phenylboronic acid affords almost
quantitative yield of the final biphenyl product in 3 h (entries 1–4,
13
94
94
470
14
467
495
464
9
2–99%). The effect of the substituents of the aryl boronic acid in
15
>99
93
this reaction is investigated. The p-bromotoluene reacts with set of
aryl boronic acid which produces the corresponding biphenyl with
moderate to excellent conversions (entries 5–8, 80–99%). This pro-
cess was also tolerant of ortho-substituents as evidenced by the suc-
cessful coupling of phenylboronic acid with 2-bromotoluene (entries
16
1
7
8
>99c
58d
495
290
9–12, 78–92%). As for the non-activated substrate p-bromoanisole,
1
Table 3
Effect of low catalyst loading.
a
a
2
General conditions: ArX (5 mmol), PhB(OH) (7.5 mmol), catalyst (0.001 mmol),
K
2
CO
3
(1.5 mmol).
b
All conversions determined by 1H-NMR spectroscopy, average of at least two runs.
Reaction was completed in 1 h.
c
d
e
The reaction was carried out in 12 h.
TON = moles of product per mole of catalyst.
Entry
C:S ratio
Time (h)
Conversion (%)b
TON
1
2
3
4
5
6
1:100 (RT)
1:100
1:300
1:500
1:1000
1:3000
24
3
3
3
8
50
250
99
297
495
810
2900
>99
>99
>99
81
good to excellent conversion was noticed (entries 13–16, 93–99%).
As expected, very satisfactory results were obtained for all the
electron-deficient substrate in the boronic acid entries 2, 6, 10 and
12
58
1
4 with conversions of 95%, 99% and 78% and 94% respectively. Fur-
a
Reaction conditions: 4-Bromoacetophenone (0.5 mmol), phenylboronic acid
0.75 mmol), base (1.5 mmol) and solvent (5 mL).
ther, we have performed the Suzuki–Miyaura reaction of aryl iodide
and aryl chloride with aryl boronic acid to test the reaction feasibility.
Aryl chlorides are especially desirable substrates for metal-catalyzed
(
b
Conversion to the coupled product was determined by 1H NMR spectroscopy based
on 4-bromoacetophenone; average of two runs.

36
D. Pandiarajan et al. / Inorganic Chemistry Communications 33 (2013) 33–37
[
14] P. Kumar, P.K. Pathak, V.K. Gupta, B.K. Srivastava, B.S. Kushwaha, Flurbiprofen
and its derivatives of many therapeutic uses — a recent report, Asian J. Chem.
6 (2004) 558–562.
carbon–carbon bond forming reactions. However, they are much
less reactive than aryl bromides. Suzuki–Miyaura reaction of
p-iodoacetophenone reacts faster with arylboronic acid than that
of p-bromoacetophenone under the same experimental conditions
1
[15] F.C. Krebs, M. Jorgensen, Controlling the energy levels of conducting polymers. Hy-
drogen versus fluorine in poly(dialkylterphenylenevinylene)s, Macromolecules
35 (2002) 7200–7206.
(
entry 17). Further the p-chloroacetophenone can also react with
[
16] G.E. Collis, A.K. Burrell, D.L. Officer, β-Terthiophene aldehyde and phosphonate:
key building blocks for the synthesis of functionalised conducting polymers,
Tetrahedron Lett. 42 (2001) 8733–8735.
17] N. Miyaura, T. Yanagi, A. Suzuki, The palladium-catalyzed cross-coupling reaction
of phenylboronic acid withhaloarenes in the presence of bases, Synth. Commun.
11 (1981) 513.
phenylboronic acid with very low conversion (entry 18).
For practical applications of any catalyst systems, the lifetime of the
catalyst and its level of reusability are very important factors. In the
recycling experiment, the first reaction afforded the corresponding
coupling product in 96% conversion, and the product conversion for
the 2nd cycle was nearly (89%). However in the 3rd cycle it was reduced
to 78%. The conversion was significantly dropped to 32% for the fourth
cycle. Thus, this catalyst system could be used for at least 3 times,
which is fairly good for a homogenous system.
In conclusion, mononuclear palladium(II) pyridoxal thiosemi-
carbazone complex was synthesized and characterized. The single
crystal X-ray crystal structure evidenced a square-planar geometry
around the palladium(II) center. The palladium(II) pyridoxal thio-
semicarbazone complex was found to be a highly active catalyst for
the Suzuki cross-coupling of a range of electronically varied aryl
halides with phenylboronic acid.
[
[18] N. Miyaura, A. Suzuki, Palladium-catalyzed cross-coupling reactions of organoboron
compounds, Chem. Rev. 95 (1995) 2457–2483.
19] A. Suzuki, Recent advances in the cross-coupling reactions of organoboron deriva-
[
tives with organic electrophiles, J. Organomet. Chem. 576 (1999) 147–168.
[20] S. Kotha, K. Lahiri, D. Kashinath, Recent applications of the Suzuki–Miyaura
cross-coupling reaction in organic synthesis, Tetrahedron 58 (2002) 9633–9695.
[
21] S. Darses, J.P. Genet, Potassium organotrifluoroborates: new perspectives in organic
synthesis, Chem. Rev. 108 (2008) 288–325.
[22] P.J. van Koningsbruggen, Y. Maeda, H. Oshio, Iron(III) spin crossover compounds,
Top. Curr. Chem. 233 (2004) 259–324.
[
23] V.M. Leovac, V.S. Jevtovic, L.S. Jovanovic, G.A. Bogdanovic, J. Serb. Chem. Soc. 70
2005) 393–422.
[24] L.S. Jovanovic, V.S. Jevtovic, V.M. Leovac, L.J. Bjelica, J. Serb. Chem. Soc. 70 (2005)
87–200.
(
1
[
25] W.A. Herrmann, V.P.W. Bohm, C.P. Reisinger, Application of palladacycles in Heck
type reactions, J. Organomet. Chem. 576 (1999) 23–41.
[
26] J. Dupont, M. Pfeffer, J. Spencer, Palladacycles — an old organometallic family
revisited: new, simple, and efficient catalyst precursors for homogeneous catalysis,
Eur. J. Inorg. Chem. (2001) 1917–1927.
Acknowledgments
[
27] M. Beller, H. Fischer, W.A. Hermann, K. Ofele, C. Brossmer, Palladacycles as effi-
cient catalysts for aryl coupling reactions, Angew. Chem. Int. Ed. 34 (1995) 1848.
28] D.A. Albisson, R.B. Bedford, S.E. Lawrence, P.N. Scully, Orthopalladated triaryl
phosphite complexes as highly active catalysts in biaryl coupling reactions,
Chem. Commun. (1998) 2095–2096.
Financial support by the Council of Scientific and Industrial
Research (CSIR) New Delhi [Grant 01(2156)/07/EMR-II] is gratefully
acknowledged. One of the authors D.P. thanks CSIR for the award
of Senior Research Fellowship (SRF). We thank DST-FIST, UGC-SAP
India for X-ray and NMR facilities, School of Chemistry, Bharathidasan
University, Tiruchirappalli.
[
[29] S. Gibson, D.F. Foster, G.R. Eastham, R.P. Tooze, D. Cole-Hamilton, Highly efficient
C–C coupling reactions usingmetallated benzylphosphine complexes of palladium,
J. Chem. Commun. (2001) 779–780.
[
30] R.B. Bedford, S.L. Welch, Palladacyclic phosphinite complexes as extremely high
activity catalysts in the Suzuki reaction, Chem. Commun. (2001) 129–130.
Appendix A. Supplementary material
[31] C.M. Zhang, M.L. Trudell, Palladium-bisimidazol-2-ylidene complexes as catalysts
for general and efficient Suzuki cross-coupling reactions of aryl chlorides with
arylboronic acids, Tetrahedron Lett. 41 (2000) 595–598.
Crystallographic data for the structural analysis have been de-
posited with Cambridge crystallographic center, CCDC No. 8152219.
Copies of this information may be obtained free of charge from
The Director, CCDC, 12 Union roads, Cambridge.CB2 1EZ, UK (email:
deposit@ccdc.cam.ac.uk). Complete sets of refined positional coordi-
nates as well as anisotropic thermal parameters and complete tabula-
tions of bond lengths and bond angles. Supplementary data to this
article can be found online at http://dx.doi.org/10.1016/j.inoche.
[
[
[
32] D.S. McGuinness, K.J. Cavell, Donor-functionalized heterocyclic carbene complexes
of palladium(ii): efficient catalysts for C–C coupling reactions, Organometallics 19
(2000) 741–748.
33] G.R. Rosa, G. Ebeling, J. Dupont, A.L. Monteiro, A superior non-symmetrical NCP
pincer type palladacycle catalyst precursor for the coupling of aryl boronic acids
with aryl chlorides, Synthesis 18 (2003) 2894–2897.
34] B. Ines, R. SanMartin, F. Churruca, E. Dominquez, M.K. Urtiga, M.I. Arriortua, A
nonsymmetric pincer-type palladium catalyst in Suzuki, Sonogashira, and Hiyama
couplings in neat water, Organometallics 27 (2008) 2833–2839.
[35] J.L. Bolliger, O. Blacque, C.M. Frech, Short, facile, and high-yielding synthesis of ex-
tremely efficient pincer-type Suzuki catalysts bearing aminophosphine substituents,
Angew. Chem. Int. Ed. 46 (2007) 6514–6517.
2
013.03.032.
[
36] A.M. Sheloumov, P. Tundo, F.M. Dolgushin, A.A. Koridze, Suzuki aryl coupling
catalysed by palladium bis(phosphane) pincer complexes based on ferrocene;
References
2 2 2 5 2 5 5
X-ray structure determination of {PdCl[{2,5-(tBu PCH ) C H }Fe(C H )]}OTf, Eur.
[
[
[
[
[
[
[
[
[
1] R.F. Heck, Palladium Reagents in Organic Synthesis, Academic Press, New York,
J. Inorg. Chem. (2008) 572–576.
1985.
[37] P. Pelagatti, A. Venturini, A. Leporat, M. Carcelli, M. Costa, A. Bacchi, G. Pelizzi, C.
Pelizzi, Chemoselective homogeneous hydrogenation of phenylacetylene using
thiosemicarbazone and thiobenzoylhydrazone palladium(II) complexes as cata-
lysts, J. Chem. Soc. Dalton Trans. (1998) 2715–2721.
[38] I.D. Kostas, B.R. Steele, A. Terzis, S.V. Amosova, A.V. Martynov, N.A. Makhaeva,
New palladium complexes with S- or Se-containing Schiff-base ligands as effi-
cient catalysts for the Suzuki–Miyaura cross-coupling reaction of aryl bromides
with phenylboronic acid under aerobic conditions, Eur. J. Inorg. Chem. (2006)
2642–2646.
[39] D.H. Lee, J.Y. Jung, I.M. Lee, M.J. Jin, (β-Oxoiminato)(phosphanyl)palladium com-
plexes as highly active catalysts in Suzuki Miyaura coupling reactions, Eur. J. Org.
Chem. (2008) 356–360.
[40] I.D. Kostas, F.J. Andreadaki, D.K. Demertzi, C. Prentjas, M.A. Demertzis, Suzuki–
Miyaura cross-coupling reaction of aryl bromides and chlorides with phenylboronic
acid under aerobic conditions catalyzed by palladium complexes with thiosemi-
carbazone ligands, Tetrahedron Lett. 46 (2005) 1967–1970.
2] J.P. Collman, L.S. Hegedus, J.R. Norton, R.G. Finke, Principles and Applications of
Organotransition Metal Chemistry, University Science, Mill Valley, CA, 1987.
3] B.M. Trost, T.R. Verhoven, in: G. Wilkinson, F.G. Stone, E.W. Abel (Eds.), Compre-
hensive Organometallic Chemistry, 8, Pergamon, Oxford, 1982, pp. 799–938.
4] A. Suzuki, Cross-Coupling reactions of organoboranes: an easy way to construct
C–C bonds, Angew. Chem. Int. Ed. 50 (2011) 6722–6737.
5] A. Suzuki, Y. Yamamoto, Cross-coupling reactions of organoboranes: an easy
method for C–C bonding, Chem. Lett. 40 (2011) 894–901.
6] A. Fihri, M. Bouhrara, B. Nekoueishahraki, J.M. Basset, V. Polshettiwar, Nanocatalysts
for Suzuki cross-coupling reactions, Chem. Soc. Rev. 40 (2011) 5181–5203.
7] A. Balanta, C. Godard, C. Claver, Pd nanoparticles for C–C coupling reactions,
Chem. Soc. Rev. 40 (2011) 4973–4985.
8] J.D. Sellars, P.G. Steel, Transition metal-catalysed cross-coupling reactions of
P-activated enols, Chem. Soc. Rev. 40 (2011) 5170–5180.
9] G. Bringmann, C. Gunther, M. Ochse, O. Schupp, S. Tasler, in: W. Herz, H. Falk,
G.W. Kirby, R.E. Moore (Eds.), Progress in the Chemistry of Organic Natural
Products, 82, Springer, New York, 2001, pp. 1–293.
[41] D.M. Demertzi, N. Kourkoumelis, K. Derlat, J. Michalak, F.J. Andreadaki, I.D. Kostac,
Thiosemicarbazone-derivatised palladium nanoparticles as efficient catalyst for
the Suzuki–Miyaura cross-coupling of aryl bromides with phenylboronic acid,
Inorg. Chim. Acta 361 (2008) 1562–1565.
[
[
[
[
10] K. Ding, S. Wang, Efficient synthesis of isoflavone analogues via a Suzuki coupling
reaction, Tetrahedron Lett. 46 (2005) 3707–3709.
11] G.W. Kabalka, B. Venkataiah, The total synthesis of eupomatilones 2 and 5, Tetra-
hedron Lett. 46 (2005) 7325–7328.
12] K.C. Nicolaou, C.N.C. Boddy, S. Brase, N. Winssinger, Chemistry, biology, and medi-
cine of the glycopeptide antibiotics, Angew. Chem. Int. Ed. 38 (1999) 2096–2152.
13] H. Ban, M. Muraoka, N. Ohashi, Synthesis of SMP-797: a new potent ACAT inhibitor,
Tetrahedron 61 (2005) 10081–10092.
[42] P. Paul, S. Datta, S. Halder, R. Acharyya, F. Basuli, R.J. Butcher, S.M. Peng, G.H. Lee,
A. Castineiras, M.G.B. Drew, S. Bhattacharya, Syntheses, structures and efficient
catalysis for C–C coupling of some benzaldehyde thiosemicarbazone complexes
of palladium, J. Mol. Catal. A Chem. 344 (2011) 62–73.
[43] M.U. Raja, R. Ramesh, New binuclear Pd(II) thioamide complexes for the Heck
reaction of aryl bromides, Tetrahedron Lett. 52 (2011) 5427–5430.

D. Pandiarajan et al. / Inorganic Chemistry Communications 33 (2013) 33–37
37
[
[
[
44] D. Pandiarajan, R. Ramesh, Suzuki–Miyaura cross-coupling reaction of aryl bro-
mides catalyzed by palladium(II) pyridoxal hydrazone complexes, J. Organomet.
Chem. 708–709 (2012) 18–24.
45] E. Sindhuja, R. Ramesh, Y. Liu, Palladium(II) thiocarboxamide complexes: synthe-
sis, characterisation and application to catalytic Suzuki coupling reactions, Dalton
Trans. 41 (2012) 5351–5361.
[47] S.C. Chan, L.L. Koh, P.H. Leung, J.D. Ranford, K.Y. Sim, Copper(II) complexes of
the antitumour-related ligand salicylaldehyde acetylhydrazone (H L) and the
single-crystal X-ray structures of [{Cu(HL)H O} ]·2(NO ) and [{Cu(HL) (pyridine)
(NO )} ], Inorg. Chim. Acta 236 (1995) 101–108.
[48] R. Raveendran, S. Pal, Polyhedron 27 (2008) 655.
[49] A. Bele, R. Ballesteros, F. Blanco, A. Bouillon, V. Collot, J. Dominguez, J. Lancelot, S.
Rault, Synthesis of novel triazolopyridylboronic acids and esters. Study of poten-
tial application to Suzuki-type reactions, Tetrahedron 60 (2004) 488.
2
2
2
3
3
2
46] E.W. Ainscough, A.M. Brodie, A. Dobbs, J.D. Ranford, J.M. Waters, Hexafluorosilicate
coordination to the antitumour copper(II) salicylaldehyde benzoylhydrazone (H
system: single-crystal X-ray structure of [{Cu(HL)H O} SiF ]·2H O, Inorg. Chim.
Acta 236 (1995) 83–88.
2
L)
2
2
6
2