Synthesis of sterically hindered N-benzyladamantyl substituted benzimidazol-2-ylidene palladium complexes and investigation of their catalytic activity in aqueous medium

Article abstract of DOI:10.1016/j.tet.2017.08.037

NHC-Pd-PEPPSI complexes with bulky benzyladamantyl substituted N-heterocyclic carbenes (NHC) were synthesized and characterized by NMR, HRMS, and micro analysis. These complexes were then used for Suzuki-Miyaura coupling reactions between aryl bromides an

Full text of DOI:10.1016/j.tet.2017.08.037

Accepted Manuscript
Synthesis of sterically hindered N-benzyladamantyl substituted benzimidazol-2-
ylidene palladium complexes and investigation of their catalytic activity in aqueous
medium
Zineb Imene Dehimat, Aziz Paşahan, Dahmane Tebbani, Sedat Yaşar, İsmail
Özdemir
PII:
S0040-4020(17)30877-3
10.1016/j.tet.2017.08.037
TET 28931
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 5 July 2017
Revised Date: 8 August 2017
Accepted Date: 18 August 2017
Please cite this article as: Dehimat ZI, Paşahan A, Tebbani D, Yaşar S, Özdemir İ, Synthesis of sterically
hindered N-benzyladamantyl substituted benzimidazol-2-ylidene palladium complexes and investigation
of their catalytic activity in aqueous medium, Tetrahedron (2017), doi: 10.1016/j.tet.2017.08.037.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT
Graphical Abstract
To create your abstract, type over the instructions in the template box below.
Fonts or abstract dimensions should not be changed or altered.
Leave this area blank for abstract info.
Synthesis of Sterically Hindered
N-Benzyladamantyl Substituted
Benzimidazol-2-ylidene
Palladium Complexes and Investigation
of Their Catalytic Activities in Aqueous Medium
Zineb Imene Dehimat a,b, Aziz Paşahan a, Dahmane Tebbani b, Sedat Yaşar a,*, İsmail Özdemir a
a - Inönü University, Catalysis, Research and Applied Center, Department of Chemistry, 44280 Malatya, Turkey
b- Laboratory of Natural Products of Plant Origin and Organic Synthesis, Department of Chemistry, Faculty of
Exact Sciences, University of Constantine 1, 25000 Constantine, Algeria.
Corresponding author: Sedat Yaşar, Tel:+904223773735, Fax:+904223410212, e-mail:syasar44@gmail.com

1
ACCEPTED MANUSCRIPT
Tetrahedron
journal homepage: www.elsevier.com
Synthesis of Sterically Hindered N-Benzyladamantyl Substituted
Benzimidazol-2-ylidene Palladium Complexes and Investigation of Their
Catalytic Activity in Aqueous Medium
Zineb Imene Dehimat a,b, Aziz Paşahan a, Dahmane Tebbani b, Sedat Yaşar a,*, İsmail Özdemir a
a - Inonü University, Catalysis, Research and Applied Center, Department of Chemistry, 44280 Malatya, Turkey
b-
Laboratory of Natural Products of Plant Origin and Organic Synthesis, Department of Chemistry, Faculty of Exact Sciences,
University of Constantine 1, 25000 Constantine, Algeria.
Corresponding author: Sedat Yaşar, Tel:+904223773735, Fax:+904223410212, e-mail:sedat.yasar@inonu.edu.tr
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
NHC-Pd-PEPPSI complexes with bulky benzyladamantyl substituted N-heterocyclic
carbenes (NHC) were synthesised and characterised by NMR, HRMS, and micro
analysis. These complexes were then used for Suzuki-Miyaura coupling reactions
between aryl bromides and phenylboronic acid. With low catalyst loading, all
synthesised complexes rapidly catalysed the Suzuki-Miyaura cross-coupling reaction
in i-PrOH/water (1:3 v/v) at room temperature in air. All palladium compounds were
stable and had high catalytic activity for the Suzuki-Miyaura coupling reaction.
Available online
Keywords:
N-heterocyclic carbene complex
Palladium
Suzuki coupling
Green chemistry
2009 Elsevier Ltd. All rights reserved.
1. Introduction
water. To overcome these problems, several additives have
already been successfully utilised.13-16
N-heterocyclic carbene (NHC) complexes have been
attracting considerable attention for the last 30 years due to their
unique performance in homogeneous catalysis.1-3 NHC
complexes owe this unique performance both to the strong σ-
donor ability of NHC ligands and the stability of the M-C2 bond
in extreme reaction conditions. Also, steric hindrance of NHCs
contributes to metal complex stability. Modification of the NHC
moiety has attracted great interest as a strategy to obtain better
catalytic performance under different catalytic conditions.
Another way to improve the efficiency of Suzuki catalysis in
water is the employment of hydrophilic ligands, such as N-
heterocyclic carbenes (NHCs) or phosphine ligands. Despite the
wide application and success of phosphine ligands, they suffer in
the Suzuki reaction due to toxicity, sensitivity to air and
moisture, and difficult separation from organic products. As a
result, NHCs have emerged as alternatives to phosphine ligands
due to superior features such as non-toxicity and stability in air
and moisture.17-23 The most well-known palladium catalyst series
for coupling reactions is PEPPSI-Pd (pyridine enhanced
precatalyst preparation stabilization and initiation) type
complexes.24,25 Since 2006, when Organ and co-workers reported
PEPPSI-Pd complexes that demonstrated high activity towards
C-C cross-coupling reactions,26 extensive studies on the structure
and activities of PEPPSI-Pd complexes have been published.27-29
Among the various chemical transformations catalyzed by
platinum group metals, palladium catalyzed reactions are widely
used. For example, the palladium catalyzed Suzuki-Miyaura
reaction is one of the most important and prized4 coupling
reaction used to produce various bio-active and fine chemicals.5-7
Green chemical reactions extensively use water.8 The use of
water has changed the opinion that has existed for many years
that many organic reactions occur only in organic solvents. The
Suzuki reaction is a prototypical example of the benefits of
reactions in water.9 Many strategies have been reported for the
Suzuki reaction in aqueous media that addressed water-soluble
catalysts,10 addition of organic solvents11 and ligand-free
methodology.12 However, the Suzuki reaction has some
problems, such as low substrate solubility and catalyst stability in
In this study, a series of sterically hindered PEPPSI-Pd-NHC
complexes and their catalytic applications to Suzuki-Miyaura
cross-coupling reactions in i-PrOH/water were studied.
2. Results and discussion
Our strategy was based on the construction of sterically
hindered benzyladamantyl substituted N-heterocyclic carbene
precursors from 4-adamantylbenzyl bromide (Scheme 1). This

2
Tetrahedron
ACCEPTED MANUSCRIPT
new compound was fully characterized by NMR and micro
coupling reaction of 4-bromoanisole with phenylboronic acid in
analyses. The benzylic CH2 protons had a resonance at 4.50 ppm.
To obtain the desired 1-(4-adamantylbenzyl)-3-aryl-substituted
NHC precursors, the N-benzyl substituted benzimidazols were
prepared according to our previous studies.25 The reaction of N-
benzyl substituted benzimidazol with 4-adamanthylbenzyl
bromide in N,N-dimethylformamide (DMF) resulted in 1-
benzyladmantyl-3-aryl substituted benzimiadole salts (4a–f) in
good yields (70–90%). The formation of benzyladamantyl
substituted N-heterocyclic carbene (4a–f) was clearly explicated
different solvents. The results showed that K2CO3 was the most
efficient base in i-PrOH/H2O when compared to other inorganic
bases. Also, the reaction could tolerate other inorganic bases,
which gave moderate yields of the coupled product (Table 1,
entries 2–5).
Table 1 The optimization of solvent and base for the Suzuki-
Miyaura reaction of 4-bromoanisolea
in the H and 13C spectra, where the characteristic peaks due to
1
aEntry
Solvent
i-PrOH
i-PrOH
i-PrOH
i-PrOH
i-PrOH
H2O
DMF
EtOH
MeOH
Acetone
i-PrOH/H2O
(1:3)
Base
K2CO3
Na2CO3
Cs2CO3
K3PO4
KOH
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Yield(%)b
N-CH-N moieties were observed at 11.75 (4a), 10.82 (4b), 11.56
(4c), 10.68 (4d), 11.44 (4e), and 10.41 (4f) ppm and at 152.7
(4a), 152.4 (4b), 152.5 (4c), 152.4 (4d), 152.5 (4e), and 152.2
1
2
3
4
5
6
7
8
9
65
52
44
51
40
35
45
60
58
39
96
(4f) ppm in the H and 13C NMR spectra, respectively, similar to
1
those previously reported25 in the formation of N-benzyl NHC
salts.
The reaction of N-benzyladamantyl substituted NHC ligand
precursors with PdCl2 in neat pyridine under air conditions
afforded (5a–f) 70 to 90% yields according to a modified
literature procedure (Scheme 1).26 The PEPPSI-Pd(II)-NHC
complexes were obtained as air- and moisture-stable yellow
crystals. The complexes (5a–f) were characterized by NMR,
HRMS spectroscopy and microanalyses. The 13C NMR spectra
displayed resonance due to the C2 carbene carbon atoms at δ =
164.1, 163.7, 161.9, 161.6, 161.8, and 161.4 ppm for the
complexes 5a–f, respectively. From these results, we can say that
the metal center of the 5a complex was electronically richer than
the others. This difference contributed positively to the catalytic
activity of the 5a complex in the Suzuki-Miyaura reaction.
10
11
12
13
14
15
i-PrOH/H2O
K2CO3
K2CO3
K2CO3
-
90
74
81
-
(1:1)
DMF/H2O
(1:3)
EtOH/H2O
(1:3)
i-PrOH/H2O
(1:3)
a Reaction Condition:1 mmol of 4-bromoanisole, 1.2 mmol of phenylboronic
acid, 1 mmol of base, 0,5 mol% 5a, 4 mL solvent, room temperature, 1 hour
The electrochemical properties of 5a–f were investigated on bare
platinum electrodes at a scan rate of 100mV/s in acetonitrile
containing 0.1 mM TBAPC as the supporting electrolyte. The
cyclic voltammograms of 0.5 mM 5a–f complexes are shown in
Figure 11S (see supporting information). The electrochemical
responses of 5a–f were similar: The 5a complex showed a
reversible reduction peak at Epc= -0.846 V with an associated
oxidation peak at Epa= -1.114 V and irreversible oxidation peak
at Epa= +0.712 V. The cathodic peak potential of the 5b complex
occurred at Epc= -0.941 V, while the complex was oxidized at
anodic potentials of Epa= -1.265 V and Epa= +0.649 V. The 5c
complex was only reduced at Epc= -0. 939 V and oxidized at
Epa= -1.277 V and Epa= +0.583 V. The reduction peak of the 5d
complex appeared at one potential, Epc= -0, 950 V, while the
oxidation peak of the complex appeared at two potentials, Epa= -
1.214 V and Epa= +0.625 V. The cyclic voltammogram of the 5e
complex showed a reversible reduction peak at Epc= -0.876 V
with an associated oxidation peak at Epa= -1.214 V and
irreversible oxidation peak at Epa= +0.650 V. The cathodic peak
potentials of the 5f complex occurred at Epc= -1.288 V and Epc=
-1.025 V, while the complex was oxidized at anodic peak
potentials of Epa= -1.304 V and Epa= +0.655 V. According to
these cyclic voltammetry (CV) results, the 5a complex had the
lowest reduction and lowest oxidation potentials.
b Isolated yield.
Secondly, the reaction was tested in different solvents.
According to the literature, water is a very important solvent for
the Suzuki reaction as it increases the reactivity.30 Thus, we tried
combinations of solvents such as i-PrOH/H2O, DMF/H2O, and
EtOH/H2O. We found i-PrOH/H2O to be the most useful
combination of solvents, and it gave excellent results (Table 1,
entries 11–12). This difference in reactivity may be attributed to
the good solubility of the carbonate base in water and palladium-
PEPPSI complexes in i-PrOH. These helped to increase the
amount of the cross-coupled product in our catalytic system. On
the other hand, water, i-PrOH, DMF, and DMF:H2O solutions
were not as effective solvents or solvent combinations as the i-
PrOH/H2O (1:3) solvent combination (Table 1, entries 1–10).
However, the reaction in this solvent combination did not
produce product in the absence of base (Table 1, entry 15).
Then, to evaluate the scope of the limitations of the protocol
we had developed, different aryl bromides were examined in our
catalytic system. As shown in Table 2, either electron-donating
or electron-withdrawing groups bearing aryl bromides and
phenylboronic acid effectively afforded the corresponding
coupled products in good yields (61–99 %) in isopropanol:water
mixture in a very short time at room temperature (Table 2, entries
1–5). For example, 4-bromoacetophenone afforded a quantitative
yield in 10 min, resulting in a TOF of 800 h-1 (Table 2, entry 3).
However, electron-donating aryl bromides showed slightly lower
activity than electron-withdrawing aryl bromides due to the effect
of the electron-donating substituents on the nucleophilicity of the
aryl bromides (Table 2, entries 1,3). A trace amount of homo-
coupling by-product was observed, although cross-coupling
reactions were carried out in air. The complex 5a had higher
catalytic activity when compared to other complexes. We
attribute this higher performance to the electronically richer
In order to reveal the catalytic activity of the
benzyladamantyl substituted PEPPSI-Pd-NHC complexes, 5a
was subjected to a Suzuki-Miyaura coupling reaction. We
optimized the reaction condition by investigating base- and
solvent-dependent conversions of the reaction between 4-
bromoanisol substrate (1 mmol) with 5a (0.5 mol %) at room
temperature. It is well-known that the base has a critical
importance in determining the efficiency of the Suzuki reaction
when water is used as solvent. Therefore, firstly, the effect of
different bases was investigated for the 5a catalyzed Suzuki

3
palladium center of the 5a complex, which in turn is due to the
lower field resonance of C2. Also, this catalytic system is almost
equally effective for electronically rich and poor aryl bromides.
Thus, our system shows a significant improvement in the
production of coupled product when compared to related
literature,32 as it can be done at room temperature, in a very short
time, using green solvents, with low catalyst loading (0.5 mol%),
and without using any additives.
electrochemical analyzer. A three-electrode electrochemical cell
ACCEPTED MANUSCRIPT
system was employed, consisting of an Ag/AgCl (CHI) electrode
as the reference, a platinum disk (CHI, 2 mm diameter) as the
working electrode, and a platinum wire in the form of a spiral as
the counter electrode, with acetonitrile that contained tetrabutyl-
ammoniumperchlorate (TBAP) as the supporting electrolyte.
Electrochemical grade TBAP and acetonitrile were purchased
from Sigma-Aldrich. CV of 5a–f complexes were studied in the
potential range of +1.0 to -2.0 V at a scan rate of 100mV/s. The
HRMS analyses were carried out with a Shimadzu LCMS-IT-
TOFF instrument. All commercial compounds were used as
obtained. All coupling products of the Suzuki-Miyaura reactions
were previously reported compounds.
Table 2 Catalytic activities of 5a-f complexes in the Suzuki
coupling reactions under optimized conditions.a
5a-f (0.5 mol%)
+
Br
R
R
B(OH)2
i-PrOH/H2O, K2CO3
[catalyst]/yield (%)b
Entry
Product
4.2. Synthesis
5a
96,
5b
5c
5d
5e
5f
95,
33c
Synthesis of 4-adamantanetoluene (1)
1
33c,
77d
60c,
97d,
99e
97,
61
66
78
68
Compound 1 was synthesized according to literature.31a Under
argon atmosphere 1-bromoadamantane (0.215g. 1.0mmol),
toluene (3.5ml) and a catalytic amount of InCl3 (5 mol٪) were
added to a round bottom flask. After stirring for 24 h at room
temperature, the mixture was washed by water (3×10 mL) until
the pH will be neutral then the mixture extracted with ether spirit
(3×25ml). The organic layer was dried over anhydrous MgSO4
and concentrated under vacuum. The solid residue was filtered in
a small column with hexane give the title compound 1 (210 mg,
93%) gave as white crystals; [Found: C, 90.32; H, 9.80. C17H22
96e,
63c
2
97e
57
97e 95e 97e
3
4
5
80
87
84
80
75
74
69
81
50d
96d,e 88
96e
95e 96e
93e 93e 95e
a reaction condition: 0.5 mol٪ 5a-f, 1 mmol p-R-C6H4Br, 1.1 mmol
phenylboronic acid, 1.0 mmol K2CO3, rt, 1h.
b Isolated product
1
requires C, 90.20; H, 9.80%]. H NMR (400 MHz, CDCl3):
c use 2 mmol of substrate.
δ=7.23–7.16 (2H, m, CH3C6H4Ad), 7.06 (2H, d, J = 8.0 Hz,
CH3C6H4Ad), 2.25 (3H, s, CH3C6H4Ad), 2.01 (3H, s, HAd), 1.83
(6H, d, J = 2.9 Hz, HAd), 1.76 –1.62 (6H, m, HAd); 13C NMR (100
MHz, CDCl3) δ=148.5, 134.9, 128.8, 124.7, 43.3, 36.8, 35.8,
29.0, 20.9.ꢀ
d use 0.25 mol٪ of Pd-NHC.
e 10 min.
3. Conclusion
We successfully synthesized six novel benzyladamantyl-
subtituted benzimidazol salts and six of their palladium
complexes. The electrochemical properties of the PEPPSI-Pd
complexes were investigated by using CV technique. From the
voltammetry results, it was found that these complexes exhibited
similar electrochemical responses and were electroactive in the
range of -1.214 to +0.583 V. For the PEPPSI-Pd-NHC
complexes, an appropriate catalytic system has been developed
for the palladium catalyzed Suzuki-Miyaura reaction in
isopropanol/water. The complex 5a has shown better catalytic
activity than other complexes on Suzuki coupling reaction of
various aryl bromides in room temperature due to lower
reduction and oxidation potentials value. To compare the
catalytic activity of our system with recently published data,
there are a few reports in the literature on Suzuki-Miyaura cross-
coupling of aryl bromides in aqueous media at room temperature
catalysed by Pd complexes.32-40 Here, the yield is better than the
literature40 when considering the amount of catalyst, time,
temperature and solvent system. This catalytic system offers a
mild and efficient alternative to existing methods, since it
proceeds at room temperature, under air, in green solvents, and
with low catalyst loading.
4.2.1. Synthesis of 4-benzyladamantyl bromide (2)
Compound
2
was synthesized according to literature.31b
Coumpond (1) (1g, 4.42 mmol), N-bromosuccinimide (NBS,
0.866g, 4.86 mmol), 2.2’-azobisisobutyronitrile (AIBN, 0.018 g,
0.11 mmol) and cyclohexane (7 mL) were added to a round
bottom flask at room temperature. The mixture was stirred and
refluxed for 2h. The reaction was monitored by TLC. Then the
mixture was allowed to cool to room temperature and water (30
ml) was added and reside was extracted with ethyl acetate (3×10
ml), dried over anhydrous MgSO4 and concentrated under
vacuum. The residue was filtered in a small silica column and to
give the title compound 2 (85%) as white solid; [Found: C,
84.30; H, 7.85; N, 8.32. C24H26N2 requires C, 84.17; H, 7.65; N,
8.18]. 1H NMR (400 MHz, CDCl3): δ=7.34 (4H, s, CH2C6H4Ad),
4.50 (2H, s, CH2C6H4Ad), 2.09 (3H, s, HAd), 1.90 (6H, t, J = 4.7
Hz, HAd), 1.77 (6H, q, J = 12.2 Hz, HAd); 13C NMR (100 MHz,
CDCl3) δ 151.8, 134.8, 128.8, 125.4, 43.0, 36.7, 36.2, 33.7, 28.8.
4.2.2. Synthesis of N-substituted benzyladamantyl benzimidazole
(3)
Compound 3 was synthesized according to literature.25[Found: C,
66.98; H, 7.02. C17H21Br requires C, 66.89; H, 6.93%].
4. Experimental section
4.1. General remarks
1H NMR (400 MHz, CDCl3): δ= 7.82 (s, 1H, NCHN), 7.57 (s,
1H, C6H2(CH3)2), 7.32 (s, 1H, C6H2(CH3)2), 7.30 (s, 1H,
CH2C6H4Ad), 7.14 – 7.07 (m, 3H, CH2C6H4Ad), 5.27 (s, 2H,
CH2C6H4Ad), 2.35 (d, J = 8.7 Hz, 6H, C6H2(CH3)2), 2.08 (s,
3H, HAd), 1.88 (t, J = 6.6 Hz, 6H, HAd), 1.75 (q, J = 12.2 Hz,
6H, HAd); 13C NMR (101 MHz, CDCl3) δ 151.4, 142.5, 132.8,
132.5, 132.1, 131.1, 126.8, 125.5, 120.3, 110.1, 48.3, 43.1,
36.7, 36.1, 28.8, 20.5, 20.2. [Found: C, 66.98; H, 7.02. C17H21Br
requires C, 66.89; H, 6.93%].
1
The H and 13C NMR spectra were recorded with a Bruker
Avance III 400 MHz NMR spectrometer with sample solutions
prepared in CDCl3. The chemical shifts were reported in δ units
downfield from the internal reference (Me4Si). IR spectra were
recorded with a PerkinElmer Spectrum 100 GladiATR FT/IR
spectrometer. Cyclic voltammetry of 5a–f complexes was
performed with a BAS (Bioanalytical Systems, Inc.) 100 BW

4
Tetrahedron
142.6, 137.4, 134.1, 133.6, 131.7, 131.6, 129.9, 127.9, 127.1,
ACCEPTED MANUSCRIPT
Br
+
Br
127.0, 125.8, 124.7, 113.9, 113.5, 51.3, 48.2, 43.0, 36.6, 36.2,
ii
i
1
2
H
28.8.
93%
85%
N
4.2.5. 1,3-Bis-(4-adamantylbenzyl)-5,6-dimethylbenzimidazolium
bromide (4c),
N
R
iii
The synthesis of 4c was performed following the same procedure
employed for the preparation of 4a, starting from 1 mmol of 1-
benzyladamanthyl-5,6-dimethylbenzimidazole and 1.2 mmol of
4-adamanthylbenzyl bromide to give the title compound 4c (540
mg, 80٪) as white solid; m.p= decompose at 344.3 oC. [Found: C,
76.42; H, 7.61; N, 4.15. C43H51N2Br requires C, 76.42; H, 7.61;
N, 4.15 %]. ꢀ1H NMR (400 MHz, CDCl3): δ=11.56 (1H, s,
NCHN), 7.41 – 7.22 (10H, m, C6H2(CH3)2-5,6 and CH2C6H4Ad),
5.67 (4H, s, CH2C6H4Ad), 2.28 (6H, s, C6H2(CH3)2), 2.00 (6H, s,
HAd), 1.83 – 1.59 (24H, m, HAd) ; 13C NMR (100 MHz, CDCl3):
δ=152.5, 141.7, 137.3, 129.9, 129.8, 128.0, 125.9, 113.3, 51.0,
43.0, 36.6, 36.2, 28.8.
PdCl2
v
R1X
iv
Cl
Pd N
Cl
N
N
N
N
N
N
R
R
R
R1
R1
3
5
4
70-90%
80-90%
80%
R=H
R1=
R=5,6-dimethyl
R=H
R1=
R1=
(a)
(b)
(c)
4.2.6.
1-(4-Adamantylbenzyl)-3-(2,4,6-trimethylbenzyl)-5,6-
R=5,6-dimethyl
R=5,6-dimethyl
R=5,6-dimethyl
dimethylbenzimidazolium chloride (4d),
The synthesis of 4d was performed following the same procedure
employed for the preparation of 4a, starting from 1 ꢀmmol of 1-
benzyladamanthyl-5,6-dimethylbenzimidazole and 1.2 mmol of
2,4,6-trimethylbenzyl chloride to give the title compound 4d (447
mg, 83٪) as white solid; m.p= decompose at 330.2 oC. [Found: C,
80.23; H, 8.06; N, 5.26. C36H43N2Cl requires C, 80.19; H, 8.04;
N, 5.20 %]. 1H NMR (400 MHz, CDCl3): δ=10.68 (1H, s,
NCHN), 7.26 (5H, d, J =5.8 Hz, C6H2(CH3)2-5,6 and
CH2C6H4Ad), 6.97 (1H, d, J = 16.3 Hz, C6H2(CH3)2-5,6), 6.86
R1=
R1=
R1=
(e)
(d)
(f)
Scheme 1. Synthesis of benzyladamanthyl substituted NHC and
their PEPPSI-Pd complexes. i)33a InCl3 (5 mol%). ii)33b (NBS, 1.1
mmol), 2.2’-azobisisobutyronitrile (AIBN, 0.025mmol) and
cyclohexane
(7ml).
iii)25
Benzimidazole
or
5,6-
dimethylbenzimidazole (1 mmol), KOH (1 mmol), ethanol (30
mL), reflux, 24 h. ıv)25 R1X (1.2 mmol), DMF (5 mL), 80 C,
o
(2H, d,
J=8.7 Hz, CH2C6H2(CH3)3-2,4,6), 5.71 (2H, s,
24h. v) 26 PdCl2 (1 mmol), pyridine, 80 oC, 24h.
CH2C6H2(CH3)3-2,4,6), 5.68 (2H, s, CH2C6H4Ad), 2.26 (3H, s,
CH2C6H2(CH3)3-2,4,6), 2.25 (6H, s, CH2C6H2(CH3)3-2,4,6), 2.23
(3H, s, C6H2(CH3)2-5,6), 2.21 (3H, s, C6H2(CH3)2-5,6), 2.00 (3H,
s, HAd), 1.79 – 1.60 (12H, m, HAd) ; 13C NMR (100 MHz,
CDCl3): δ= 152.4, 141.1, 139.8, 138.0, 137.9, 137.3, 137.3,
130.2, 130.0, 127.6, 125.8, 125.0, 113.4, 113.2, 51.1, 46.9, 43.0,
36.6, 36.2, 28.8.
4.2.3.
1-(4-Adamantylbenzyl)-3-(4-ter-
butylbenzyl)benzimidazolium bromide (4a),
A mixture of 1-(4-adamantylbenzyl)benzimidazole (1 mmol) and
4-alkylbenzylbromide (1.1 mmol) in dimethyl formamide (DMF;
3 mL) was stirred and heated for 2 days at 70 °C. Diethyl ether
(15 mL) was added to obtain a white crystalline solid which was
filtered off. The solid was washed with diethyl ether (3×15 mL),
and dried under a vacuum to give the title ꢀcompound 4a (500
4.2.7.
1-(4-Adamantylbenzyl)-3-(3,5-dimethylbenzyl)-5,6-
dimethylbenzimidazolium bromide (4e),
o
mg, 88٪) as white crystals; m.p= 309.5 C. [Found: C, 73.87; H,
The synthesis of 4e was performed following the same procedure
employed for the preparation of 4a, starting from 1 mmol of 1-
benzyladamanthyl-5,6-dimethylbenzimidazole and 1.2 mmol of
3,5-dimethylbenzyl bromide to give the title compound 4e (507
7.35; N, 5.03. C35H41N2Br requires C, 73.80; H, 7.25; N, 4.92 %].
1H NMR (400 MHz, CDCl3): δ= 11.75 (1H, s, NCHN), 7.54 (2H,
dt, J = 7.0, 3.5 Hz, C6H4), 7.47–7.39 (6H, m, C6H4 and
CH2C6H4Ad and CH2C6H4(CH3)3-4), 7.30 (4H, dd, J=11.8, 8.3
Hz, CH2C6H4Ad and CH2C6H4(CH3)3-4), 5.75 (2H, s,
CH2C6H4(CH3)3-4), 5.23 (2H, s, CH2C6H4Ad), 2.00 (3H, s, HAd),
1.84–1.61 (12H, m, HAd), 1.20 (9H, s, CH2C6H4(CH3)3-4) ; 13C
NMR (100 MHz, CDCl3): δ=152.7, 152.5, 143.0, 131.4, 129.5,
128.2, 128.2, 127.1, 126.4, 125.9, 113.8, 113.7, 51.4, 51.3, 43.0,
36.6, 36.2, 34.7, 31.2, 28.8.
o
mg, 89٪) as white solid; m.p= 281.3 C. [Found: C, 80.10; H,
7.94; N, 5.41. C35H41N2Cl requires C, 80.05; H, 7.87; N, 5.33 %].
1H NMR (400 MHz, CDCl3): δ=11.44 (1H, s, NCHN), 7.36 (2H,
d, J = 8.3, CH2C6H4Ad), 7.28 (2H, d, J = 8.3 Hz, CH2C6H4Ad),
7.21 (2H, d,
J = 2.3 Hz, C6H2(CH3)2), 6.95 (2H, s,
CH2C6H3(CH3)2-3,5), 6.89 (1H, d, J = 16.5 Hz, CH2C6H3(CH3)2-
3,5), 5.71 (2H, s, CH2C6H3(CH3)2-3,5), 5.62 (2H, s, CH2C6H4Ad),
2.28 (3H, s, CH2C6H3(CH3)2-3,5), 2.27 (3H, s, CH2C6H3(CH3)2-
3,5), 2.21 (6H, s, C6H2(CH3)2), 2.00 (3H, s, HAd), 1.72 (12H, m, J
= 48.0 Hz, HAd); 13C NMR (100 MHz, CDCl3): δ=152.5, 141.8,
139.1, 137.3, 132.6, 130.8, 130.0, 129.9, 129.9, 128.1, 125.9,
125.7, 113.3, 113.3, 51.3, 51.0, 43.0, 36.6, 36.2, 28.8.
4.2.4.
1-(4-Adamantylbenzyl)-3-(2,3,4,5,6-
pentamethylbenzyl)benzimidazolium chloride (4b),
The synthesis of 4b was performed following the same procedure
employed for the preparation of 4a, starting from 1 ꢀmmol of 1-
benzyladamanthyl benzimidazole and 1.2 mmol of 2,3,4,5,6-
penthamethylbenzyl chloride to give the title compound 4b (485
4.2.8.
1-(4-adamantylbenzyl)-3-(2,3,4,5,6-pentamethylbenzyl)-
o
mg, 90٪) as white solide; m.p= 300.7 C. [Found: C, 80.25; H,
5,6-dimethylbenzimidazolium bromide (4f),
8.09; N, 5.29. C36H43N2Cl requires C, 80.19; H, 8.04; N, 5.20
%].1H NMR (400 MHz, CDCl3): δ=10.82 (1H, s, NCHN), 7.56–
7.23 (8H, m, C6H4 and CH2C6H4Ad), 5.84 (2H, s, CH2C6(CH3)5),
5.76 (2H, s, CH2C6H4Ad), 2.23 (6H, s, CH2C6(CH3)5), 2.21 (3H,
s, CH2C6(CH3)5), 2.18 (6H, s, CH2C6(CH3)5), 2.00 (3H, s, HAd ),
1.79–1.61 (12H, m, HAd). 13C NMR (100 MHz, CDCl3): δ=152.4,
The synthesis of 4f was performed following the same procedure
employed for the preparation of 4a, starting from 1 mmol of 1-
benzyladamanthyl-5,6-dimethylbenzimidazole and 1.2 mmol of
2,3,4,5,6-pentamethylbenzyl chloride to give the title compound
4f (482 mg, 85٪) as white solid; m.p= 207.4 C. [Found: C,
80.51; H, 8.43; N, 5.03. C38H47N2Cl requires C, 80.46; H, 8.35;
o

5
N, 4.94 %]. 1H NMR (400 MHz, CDCl3): δ=10.41 (1H, s,
C6H2(CH3)2 ), 7.35 (6H, dd, J = 25.3, 17.3 Hz, CH2C6H4Ad),
ACCEPTED MANUSCRIPT
NCHN), 7.35 – 7.28 (5H, m, CH2C6H4Ad and C6H2(CH3)2), 7.22
(1H, s, C6H2(CH3)2), 5.87 (2H, s, CH2C6(CH3)5), 5.72 (2H, s,
CH2C6H4Ad), 2.37 (3H, s, C6H2(CH3)2), 2.35 (3H, s,
C6H2(CH3)2), 2.32 – 2.26 (15H, m, CH2C6(CH3)5), 2.08 (3H, s,
HAd), 1.88 – 1.70 (12H, m, HAd ) ; 13C NMR (100 MHz, CDCl3):
δ=152.2, 141.1, 137.4, 137.3, 137.2, 134.1, 133.6, 130.3, 130.1,
127.7, 125.7, 124.7, 113.4, 113.1, 51.0, 47.6, 43.0, 36.6, 36.1,
28.8.
6.87 (2H, t, J=12.1 Hz, CH2C6H4Ad), 6.29–6.07 (4H, m,
CH2C6H4Ad), 2.20 (6H, s, C6H2(CH3)2), 2.10 (6H, s, HAd), 1.92
(12H, s, HAd), 1.79 (12H, s, HAd). 13C NMR (100 MHz, CDCl3):
δ=161.9, 152.6, 151.9, 151.3, 151.1, 137.9, 133.3, 132.4, 127.7,
125.3, 124.4, 111.7, 52.9, 43.1, 36.8, 36.1, 28.9. HRMS(ESI) for
+
C43H50N2 (M++H): calcd. 595.4052, found 595.4048.
4.2.12.
Dichloro[1-(4-adamantylbenzyl)-3-(2,4,6-
trimethylbenzyl)-5,6-dimethylbenzimidazole-2-
ylidene]pyridinepalladium(II), 5d
4.2.9. Dichloro[1-(4-adamantylbenzyl)-3-(4-ter-
butylbenzyl)benzimidazole-2-ylidene]pyridinepalladium(II), 5a
The synthesis of 5d was performed following the same procedure
employed for the preparation of 5a, starting from 4d to give the
title compound 5d (561 mg, 74٪) as yellow crystal; m.p= 185.4
oC. ν(CN)=1445.32 cm-1. [Found: C, 64.89; H, 6.28; N, 5.59.
In air, a pressure tube was charged with PdCl2 (180 mg, 1
mmol), 4a (1.1 mmol), K2CO3 (700 mg, 5 mmol) and 3 mL of
pyridine. The reaction mixture was heated with vigorous stirring
for 7 h at 80 oC then cooled to room temperature and diluted
with dichloromethane (DCM). A short silica column was used for
filtration. All volatiles were evaporated. Residue yellow solid
was washed with hexane (2x10 mL) and diethyl ether (2x10 mL).
Yellow solid was crystallized by DCM/Hexane (1:3) at room
temperature to give the title compound 5a (603 mg, 81٪) as
1
C41H47N3Cl2Pd requires C, 64.87; H, 6.24; N, 5.54 %]. H NMR
(400 MHz, CDCl3): δ=9.01 (2H, d, J = 6.3 Hz, NC5H5), 7.77 (1H,
s, NC5H5), 7.57 (2H, d, J = 7.9 Hz, NC5H5), 7.37 (4H, d, J=7.6
Hz, C6H2(CH3)2 and CH2C6H2(CH3)3-2,4,6 ), 7.02–6.74 (3H, m,
CH2C6H4Ad), 6.16 (5H, dt, J = 36.1, 21.1 Hz, CH2C6H4Ad,
CH2C6H2(CH3)3-2,4,6 and CH2C6H4Ad), 2.38 (9H, d, J = 6.7 Hz,
CH2C6H2(CH3)3-2,4,6), 2.17 (3H, m, C6H2(CH3)2), 2.10 (3H, s,
HAd), 2.03 (3H, m, C6H2(CH3)2), 1.91 (6H, s, HAd), 1.78 (6H, q, J
= 12.3 Hz, HAd). 13C NMR (100 MHz, CDCl3): δ=161.6, 152.6,
152.1, 151.0, 139.0, 138.9, 137.9, 132.4, 131.9, 131.7, 129.5,
127.7, 125.3, 124.4, 111.7, 53.0, 50.2, 43.1, 36.8, 36.1, 28.9.
HRMS (ESI) for C41H47N3Pd+ (M+-2Cl) calcd. 687.2805, found
687.1395; for C36H42N2Pd+ (M++H] calcd. 609.2461 found
609.2292.
o
yellow crystal; m.p= 214.6 C. ν(CN)= 1446.93 cm-1. [Found: C,
64.54; H, 6.17; N, 5.74. C40H45N3Cl2Pd requires C, 64.68; H,
1
6.09; N, 5.64 %]. H NMR (400 MHz, CDCl3): δ= 9.05 (2H, d, J
= 5.1 Hz, NC5H5), 7.78 (1H, d, NC5H5) 7.66 – 7.52 (4H, m,
NC5H5 and C6H4), 7.45 – 7.32 (6H, m, CH2C6H4(CH3)3-4, C6H4
and CH2C6H4Ad), 7.17 – 7.05 (4H, m, CH2C6H4(CH3)3-4 and
CH2C6H4Ad ), 6.31 – 6.17 (4H, m, CH2C6H4(CH3)3-4 and
CH2C6H4Ad), 2.10 (3H, s, HAd), 1.92 (6H, s, HAd), 1.78 (6H, q, J
= 12.3 Hz, HAd), 1.32 (9H, s, CH2C6H4(CH3)3-4 ). 13C NMR (100
MHz, CDCl3): δ=164.1, 164.0, 152.7, 152.1, 151.3, 151.1, 138.0,
134.7, 132.0, 127.8, 125.8, 125.2, 124.5, 123.1, 111.5, 53.5, 53.2,
43.1, 36.8, 36.1, 34.6, 31.3, 28.9. HRMS(ESI) for C35H40N2PdCl2
(M-H): calcd. 663.1525, found 663.2485; C35H40N2Pd+ (M+-H):
calcd. 593.2148, found 593.2130.
4.2.13. Dichloro[1-(4-adamantylbenzyl)-3-(3,5-dimethylbenzyl)-
5,6-dimethylbenzimidazole-2-ylidene]pyridine palladium(II), 5e
The synthesis of 5e was performed following the same procedure
employed for the preparation of 5a, starting from 4e to give the
title compound 5e (603 mg, 81٪) as yellow crystal; m.p=
4.2.10.
Dichloro[1-(4-adamantylbenzyl)-3-(2,3,4,5,6-
o
decompose at 350 C. ν(CN)=1446.30 cm-1. [Found: C, 64.55; H,
pentamethylbenzyl)benzimidazole-2-
ylidene]pyridinepalladium(II), 5b
6.18; N, 5.77. C40H45N3Cl2Pd requires C, 64.48; H, 6.09; N, 5.64
1
%]. H NMR (400 MHz, CDCl3): δ=8.92 (2H, d, J = 4.9 Hz,
The synthesis of 5b was performed following the same procedure
ꢀemployed for the preparation of 5a, starting from 4b to give the
title compound 5b (637 mg, 84٪) as yellow crystal; m.p= 204.7
oC. ν(CN)=1442.18 cm-1. [Found: C, 64.96; H, 6.31; N, 5.67.
NC5H5), 7.66 (1H, s, NC5H5), 7.50 (2H, d, J = 8.0 Hz, NC5H5),
7.32 – 7.10 (6H, m, C6H2(CH3)2 and CH2C6H4Ad ), 6.91 – 6.71
(3H, m, CH2C6H3(CH3)2-3,5 ), 6.18
–
5.91 (4H, m,
1
CH2C6H3(CH3)2-3,5 and CH2C6H4Ad), 2.23 (6H, s,
CH2C6H3(CH3)2-3,5), 2.11 (6H, s, C6H2(CH3)2), 2.00 (3H, s, HAd),
1.82 (6H, s, HAd), 1.74 – 1.62 (6H, m, HAd). 13C NMR (100 MHz,
CDCl3): δ=161.9, 152.7, 152.1, 151.3, 151.1, 138.3, 137.9, 135.2,
133.4, 133.2, 132.2, 129.6, 127.8, 127.7, 125.7, 125.3, 124.4,
111.7, 53.2, 52.9, 43.2, 36.8, 36.1, 28.9. HRMS (ESI) for
C35H40N2Pd+ (M+-H) calcd. 593.2148, found 593.2094; for
C35H39N2Pd+ (M++2H] calcd. 489.3270 found 489.3251.
C41H47N3Cl2Pd requires C, 64.87; H, 6.24; N, 5.54 %]. H NMR
(400 MHz, CDCl3): δ=8.99 – 8.85 (2H, m, NC5H5), 7.69 (1H, m,
NC5H5), 7.48 (2H, t, J = 11.0 Hz, NC5H5), 7.32 – 7.22 (4H, m,
C6H4), 7.07 – 6.71 (3H, m, CH2C6H4Ad), 6.34 – 6.02 (5H, m,
CH2C6H4Ad, CH2C6(CH3)5 and CH2C6H4Ad ), 2.28 – 2.24 (9H, s,
CH2C6(CH3)5), 2.18 (6H, s, CH2C6(CH3)5), 2.00 (3H, s, HAd),
1.81 (6H, s, HAd), 1.67 (6H, q, J = 12.2 Hz, HAd). 13C NMR (100
MHz, CDCl3): δ=163.7, 152.6, 152.0, 151.3, 151.2, 138.0, 136.0,
135.3, 134.7, 133.1, 132.1, 127.8, 125.3, 124.5, 122.9, 122.5,
111.5, 53.4, 51.9, 43.1, 36.8, 36.1, 28.9. HRMS(ESI) for
C36H42N2Pd+ (M+-H): calcd. 607.2305, found 607.2271;
C36H42N2+ (M++H): calcd. 503.3426, found 503.3361. [Found: C,
64.96; H, 6.31; N, 5.67. C41H47N3Cl2Pd requires C, 64.87; H,
6.24; N, 5.54 %].
4.2.14.
Dichloro[1-(4-adamantylbenzyl)-3-(2,3,4,5,6-
pentamethylbenzyl)-5,6-dimethylbenzimidazole-2-
ylidene]pyridinepalladium(II), 5f
The synthesis of 5f was performed following the same procedure
employed for the preparation of 5a, starting from 4f to give the
title compound 5f (710 mg, 90٪) as yellow crystal; m.p= 236.3
oC. ν(CN)=1444.74 cm-1. [Found: C, 65.66; H, 6.61; N, 5.43.
4.2.11.
Dichloro[1,3-bis-(4-adamantylbenzyl)-5,6-
1
dimethylbenzimidazole-2-ylidene]pyridinepalladium(II), 5c
C43H51N3Cl2Pd requires C, 65.61; H, 6.53; N, 5.34 %]. H NMR
(400 MHz, CDCl3): δ=8.92–8.80 (2H, m, NC5H5), 7.66 (1H, s,
NC5H5), 7.47 (2H, d, J = 8.1 Hz, NC5H5), 7.25 (4H, dd, J = 15.3,
7.3 Hz, C6H2(CH3)2 and CH2C6H4Ad ), 6.71 (1H, t, J = 13.3 Hz,
CH2C6H4Ad), 6.17 – 5.91 (5H, m, CH2C6H4Ad, CH2C6(CH3)5 and
CH2C6H4Ad ), 2.25-2.18 (15H, m, CH2C6(CH3)5), 2.05 (3H, m,
C6H2(CH3)2), 2.00 (3H, s, HAd), 1.93 (3H, m, C6H2(CH3)2), 1.81
(6H, s, HAd), 1.68 (6H, q, J = 12.3 Hz, HAd). 13C NMR (100 MHz,
The synthesis of 5c was performed following the same
procedure employed for the preparation of 5a, starting from 4c to
give the title compound 5c (596 mg, 70٪) as yellow crystal; m.p=
decompose at 300.6 oC. ν(CN)=1447.42 cm-1. [Found: C, 67.79; H,
6.61; N, 5.05. C48H55N3ClPd requires C, 67.72; H, 6.51; N,
1
4.94%]. H NMR (400 MHz, CDCl3): δ=9.02 (2H, s, NC5H5),
7.76 (1H, s, NC5H5), 7.59 (4H, d, J = 7.3 Hz, NC5H5 and

6
Tetrahedron
10. (a) Plenio, C. A.; Fleckenstein, H. Green Chem. 2007, 9,
CDCl3): δ=161.4, 152.6, 152.0, 151.2, 151.0, 137.8, 135.2,
ACCEPTED MANUSCRIPT
134.8, 133.9, 133.0, 132.3, 131.7, 128.2, 127.7, 125.2, 124.4,
111.9, 111.4, 53.1, 51.3, 43.1, 36.8, 36.1, 28.9. HRMS (ESI) for
C38H46N2+ (M++H) calcd. 531.3739, found 531.3678.
1287; (b) Shaughnessy, R. Huang, K.; H. Organometallics.
2006, 25, 4105.
11. (a) Hor, F.; Li, T. S. A. Adv. Synth. Catal. 2008, 350, 2391;
(b) Moore, L. R.; Western, E. C.; Craciun, R.; Spruell, J. M.;
Dixon, D. A.; Shaughnessy, K. P.; O’Halloran, K. H.
Organometallics. 2008, 27, 576; (c) Čapek, P.; Hocek, R.;
Pohl, M. Org. Biomol. Chem. 2006, 4, 2278.
4.2.3. General Procedure for the Suzuki Coupling Reaction
Under air, a 10 mL tube containing a stirring bar was charged
with palladium catalyst (0.5 mol %, 0.005 mmol), potassium
carbonate (138 mg,
1 mmol), aryl bromide (1 mmol),
phenylboronic acid (135 mg, 1 mmol), isopropanol (1.0 mL), and
water (3 mL). The mixture was stirred at room temperature for an
appropriate time. The reaction was quenched with water, and the
mixture was extracted with ethyl acetate, dried with MgSO4, and
filtered on short silica. The solvent was removed under reduced
pressure to give the crude product. The residue was subjected to
PTLC (hexane:ethyl acetate) (9:1) to give the pure product.
12. (a) Basu, B.; Biswas, K.; Ghosh, S.; Kundu, S. Green Chem.
2010, 12, 1734; (b) Zhang, S.; Shi, Y. Green Chem. 2008, 10,
868; (c) Maegawa, T.; Kitamura, Y.; Sako, S.; Udzu, T.;
Sakurai, A.; Tanaka, A.; Kobayashi, Y.; Endo, K.; Bora, U.;
Kurita, T.; Kozaki, A.; Sajiki, Y.; Monguchi, H. Chem.–Eur.
J. 2007, 13, 5937.
13. Mu, B.; Li, J.; Han, Z.; Wu, Y. J. Organomet. Chem.2012,
700, 117-124.
Acknowledgements
This study was financially supported by the Inönü University
research found (BAP:2016/195) and University of Constantine
for grand Zineb Imene Dehimat.
14. Leadbeater, N. E.; Marco, M. Org. Lett.2002, 4, 2973-2976.
15. Saha, D.; Chattopadhyay,K.; Ranu, B. C. Tetrahedron
Lett.2009, 50, 1003-1006.
16. Baur, M.; Frank, M.; Schatz, J.; Schildbach, F. Tetrahedron.
2001, 57, 6985-6991.
17. Scott, N. M.; Nolan, S. P. Eur. J. Inorg. Chem. 2005, 1815-
1828.
18. Wanzlick, H. W.; Schikora, E. Angew. Chem.1960, 72, 494.
19. Bourissou, D.; Guerret, O.; Gabbaï, F. P.; Bertrand, G. Chem.
Rev.2000, 100, 39-91.
20. Regitz, M. Angew. Chem. Int. Ed.1996, 35, 725-728.
21. Herrmann, W. A.; Christian, K. Angew. Chem. Int. Ed.1997,
36, 2162-2187.
References and notes
1. (a) Vougioukalakis, G. C.; Grubbs, R. H. Chem. Rev. 2010,
110, 1746-1787; (b) Colacino, E.; Martinez, J.; Lamaty, F.
Coord. Chem. Rev. 2007, 251, 726-764; (c) Samojlowicz, C.;
Bieniek, M.; Grela, K. Chem. Rev. 2009, 109, 3708-3742.
2. (a) Yus, M.; Pastor, I. M. Chem. Lett. 2013, 42, 94-108; (b)
Schaper, L.A.; Hock, S. J.; Herrmann, W. A.; Kuhn, F. E.
Angew. Chem. Int. Ed. 2013, 52, 270-289; (c) Ingleson, M. J.;
Layfield, R. A. Chem. Commun. 2012, 3579-3589.
3. Fortman, G. C.; Nolan, S. P. Chem. Soc. Rev. 2011, 40, 5151-
5169; (e) Marion, N.; Nolan, S. P. Acc. Chem. Res. 2008, 41,
1440-1449.
22. Perry, M. C.; Burgess, K.; Tetrahedron: Asymmetry. 2003,
14, 951-961.
23. Kirmse, W. Angew. Chem. Int. Ed.2010, 49, 8798-8801.
24. (a) Valente, C.; Pompeo, M.; Sayah, M.; Organ, M. G. Org.
Process Res. Dev. 2014, 18, 180-190; (b) Valente, C.;
Çalimsiz, S.; Hoi, K. H.; Mallik, D.; Sayah, M.; Organ, M. G.
Angew. Chem. Int. Ed. 2012, 51, 3314-3332; (c) Kantchev, E.
A. B.; O’Brien, C. J.; Organ, M. G. Angew. Chem. Int. Ed.
2007, 46, 2768-2813; (d) Pompeo, M.; Farmer, J. L.; Froese,
R. D. J.; Organ, M. G. Angew. Chem., Int. Ed. 2014, 53,
3223-3226; (e) Zhang, Y.; Cesar, V.; Storch, G.; Lugan, N.;
Lavigne, G. Angew. Chem. Int. Ed. 2014, 53, 6482-6486.
25. Yaşar, S.; Şahin, C.; Arslan, M.; Özdemir, İ. J. Org.Chem.
2015, 776, 107.
26. (a) O’Brien, C. J.; Kantchev, E. A. B.; Valente, C.; Hadei, N.;
Chass, G. A.; Lough, A.; Hopkinson, A. C.; Organ, M. G.
Chem. Eur. J. 2006, 12, 4743-4748. (b) Organ, M. G.; Avola,
S.; Dubovyk, I.; Hadei, N. E. A. B. O’Brien, C. J.; Valente,
C. Chem. Eur. J. 2006, 12, 4749- 4755.
27. a) Valente, C.; Baglione, S.; Candito, D.; O’Brien, C. J.;
Organ, M. G. Chem. Commun. 2008, 735-737. (b) Organ, M.
G.; Calimsiz, S.; Sayah, M.; Hou Hoi, K.; Lough, A. J.
Angew. Chem. Int. Ed. 2009, 48, 2383-2387. (c) Valente, C.;
Belowich, M. E.; Hadei, N.; Organ, M. G. Eur. J. Org. Chem.
2010, 4343-4354. (d) Pompeo, M.; Froese, R. D. J.; Hadei,
N.; Organ, M. G. Angew. Chem. Int. Ed. 2012, 51, 11354-
11357. (e) Hou Hoi, K.; Organ, M. G. Chem. Eur. J. 2012,
18, 804- 807. (f) Sayah, M.; Organ, M. G. Chem. Eur. J.
4. www.nobelprize.org
5. Littke, F. A.; Fu, G. C. Angew. Chem. Int. Ed. 2002, 41,
4176.
6. (a) Dupont, J.; Consorti, C. S.; Spencer, J. Chem. Rev. 2005,
105, 2527; (b) Gaikwad, V.; Holuigue, A.; Thathagar, M. B.;
Elshof, J. E.; Rothenberg, G. Chem. Eur. J. 2007, 13,6908.
7. (a) Suzuki, A. Angew. Chem. Int. Ed. 2011, 50, 6722; (b)
Suzuki, A.; Yamamoto, Y. Chem. Lett. 2011, 40, 894; (c)
Fihri, A.; Bouhrara, M.; Nekoueishahraki, B.;Basset, J.-M.;
Polshettiwar, V. Chem. Soc. Rev. 2011, 40, 5181; (d) Balanta,
A.; Godard, C.; Claver, C. Chem. Soc. Rev. 2011,40, 4973.
8. (a) Kappe, D.; Dallinger C. O. Chem. Rev. 2007, 107, 2563;
(b) Chen, C.-J.; Li, L. Chem. Soc. Rev. 2006, 35, 68; (c)
Sheldon, R. A. Green Chem. 2005, 7, 267.
9. (a) Modak, A.; Mondal, J. M.; Bhaumik, Sasidharan, A.
Green Chem. 2011, 13, 1317; (b) Marziale, A. N.; Jantke, D.;
Faul, S. H. ; Reiner, T.; Eppinger, E. Herdtweck and J.
Green Chem. 2011, 13, 169; (c) Polshettiwar, V.;
Decottignies, A.; Fihri, C. Len and A. ChemSusChem. 2010,
3, 502; (d) Carril, M.; Domínguez, R.; SanMartin, E. Chem.
Soc. Rev. 2008, 37, 639; (e) Herrerías, C. I.; Yao, X.; Li,
Z.;Li, C.-J. Chem. Rev. 2007, 107, 2546; (f) Li, C.-J. Chem.
Rev. 2005, 105, 3095; (g) Yamada, Y. M. A.; Takeda, K.;
Ikegami, H.; Takahashi, S. J. Org. Chem. 2003, 68, 7733; (h)
Yamada, Y. M. A.; Takeda, K.; Ikegami, H.; Takahashi, S.
Org. Lett. 2002, 4, 3371.

7
2011, 17, 11719- 11722. (g) Sayah, M.; Organ, M. G. Chem.
Eur. J. 2013, 19, 16196- 16199.
ACCEPTED MANUSCRIPT
28. Dunsford, J. J.; Cavell, K. J. Organomettallics.
2014,33,2902-2905.
29. (a) Özdemir, İ.; Gök, Y.; Özeroğlu, Ö.; Kaloğlu, M.; Doucet,
H.; Bruneau, C. Eur. J. Inorg. Chem. 2010, 1798-1805. (b)
Teci, M.; Brenner, E.; Matt, D.; Toupet, L. Eur. J. Inorg.
Chem. 2013, 2841- 2848.
30. (a) Hiroshige, M.; Zhou, J. R.; Hauske P. Tetrahedron Lett.
1995, 36, 4567; (b) Bueno, A. C.; Gusevskaya, A. O.; de
Souza, E. V. Adv. Synth. Catal. 2009, 351, 2491; (c) Conlon,
D. A.; Pipik, B.; Ferdinand, S.; Le Blond, C. R.; Sowa, J. R.;
Izzo, B.; Collins, P.; Ho, G. J.; Williams, J. M.; Sun, Y. J.;
Shi, Y. K. Adv. Synth. Catal. 2003, 345, 931; (d) Vallin, K. S.
A.; Hallberg, M.; Larhed, A. J. Org. Chem. 2001, 66, 4340;
(e) Miao, G.; Ye, P.; Baldino, L.; Yu, C. M. J. Org. Chem.
2005, 70, 2332.
31. (a) Mosset, P.;Gree, R. Synlett. 2013, 24(9): 1142-1146; (b)
Ikunaka, M.; Maruoka, K.; Okuda, Y.; Ooi, T. Organic
process Research&Development, 2003, 7, 644-648.
32. (a) Saikia, B.; Ali, A. A.; Boruah, P. R.; Sarma, D.; Barua, N.
C. New J. Chem. 2015, 39, 2440; (b) Borah, G.; Boruah, D.;
Sarmah, G.; Bharadwaj, S.K.; Bora, U. Appl. Organometal.
Chem. 2013, 27, 688; (c) Mondal, M.; Bora, U. Green Chem.
2012, 14, 1873; (d) Liu, N.; Jin, Z. Green. Chem. 2012, 14,
592; (e) Liu, C.; Zhang, Y.; Liu, N.; Qui, J. Green Chem.,
2012, 14, 2999; (e) Saikia, B.; Boruah, P. R.; Ali, A. A.;
Sarma, D. Tetrahedron Lett. 2015, 56, 33; (f) Kim, Y. -J.;
Lee, J. –H.; Kim, T.; Ham, J.; Zheng, Z. N.; Lee, S. W. Eur.
J. Chem. 2012, 6011; (g) Karimi, B.; Akhavan, P. F. Chem.
Commun. 2011, 47, 7686.
33. Gu, P.; Xu, Q.; Shi, M. Tetrahedron, 2014, 70,7886.
34. Barrios, G.G.; Hiller, J.; Peris, E. Chem. Eur. J. 2013, 19,
10405.
35. Sutar, R.L.; Kumar, V.; Shingare, R.D.; Thorat, S.; Gonnade,
R.; Reddy, S. Eur. J. Org. Chem. 2014, 4482.
36. Ren, H.; Xu, Y.; Jeanneau, E.; Bonnamour, I.; Tu, T.;
Darbost, U. Tetrahedron, 2014, 70, 2829.
37. Valds, H.; Poyatos, M.; Ujaque, G.; Peris, E. Chem. Eur. J.
2015, 21, 1578.
38. Saikia, B.; Boruah, P.R.; Ali, A.A.; Sarma, D. Tetrahedron
Lett. 2015, 56, 633.
39. Kim, Y.–J.; Lee, J.–H.; Kimm,T.; Ham, J.; Zheng, Z.N.; Lee,
S.W. Eur. J. Inorg. Chem. 2012, 6011.
40. (a) Joucla, L.; Cusati, G.; Pinel, C.; Djakovitch, L.;
Tetrahedron. Lett. 2008, 49, 4738. (b) Chatterjee, A.; Ward,
T. R. Catal Lett 2016, 146, 820. (c) Soomro, S.S.; Röhlich,
C.; Köhler, K. Adv. Synth. Catal., 2011, 353, 767. (d) Zhou,
J.; Guo, X.; Tu, C.; Li, X.; Sun, H.; J.Organomet. Chem.
2009, 694, 697. (e) Leadbeater, N.; Marco, E. M. J. Org.
Chem. 2003, 68, 888. (f) Li, Z.; Gelbaum, C.; Heaner, W. L.;
Fisk, J.; Jaganathan, A.; Holden, B.; Pollet, P.; Liotta, C. L.
Org. Process Res. Dev. 2016, 20, 1489. (g) Liang, Q.; Xing,
P.; Huang, Z.; Dong, J.; Sharpless, K. B.; Li, X.; Jiang, B.
Org. Lett. 2015, 17, 1942. (h) Boubakri, L.; Yaşar, S.; Dorcet,
V.; Roisnel, T.; Bruneau,C.; Hamdi, N.; Özdemir, İ. New J.
Chem. 2017, 41, 5105.