Catalytic cross-coupling reaction of aryl iodides with triarylbismuths by an N-heterocyclic carbene-PdCl2 based on benzo-9-crown-3 catalyst at room temperature

Article abstract of DOI:10.1016/j.mcat.2017.10.004

We have developed the N-heterocyclic carbene ligand/PdCl₂ catalyst for C[sbnd]C coupling reaction of aryl iodides and organobismuths at room temperature. The established catalytic system exhibited high cross-coupling reactivity between a variety of orgnobismuths and aryl iodides in the presence of K₂CO₃ as base in NMP or DMSO at room temperature. The simple and efficient transformation can tolerate either electron-withdrawing or electron-donating functional groups. It was notably found that both aryl bromide and aryl chloride generated moderate to good yields of the corresponding biphenyl products using 5 mol% of PPh₃/ligand 5 (1:1) as catalyst.

Full text of DOI:10.1016/j.mcat.2017.10.004

Molecular Catalysis 443 (2017) 125–130
Contents lists available at ScienceDirect
Molecular Catalysis
journal homepage: www.elsevier.com/locate/mcat
Research paper
Catalytic cross-coupling reaction of aryl iodides with triarylbismuths
by an N-heterocyclic carbene-PdCl based on benzo-9-crown-3
2
catalyst at room temperature
Jia-Qi Liua,b, Jun-Juan Yanga,b, Jun-Fei Lia,b, Kai Li , Xue-Dong Xiaoa,b, Ya-Li Baia,b
Jun-Wen Wang
a
b
,
a,b,∗
Key Laboratory of Magnetic Molecules & Magnetic Information Materials Ministry of Education, Shanxi Normal University, Linfen, 041004, China
The school of Chemical and Material Science, Shanxi Normal University, No. 1, Gongyuan Street, Linfen, 041004, China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 July 2017
Received in revised form
We have developed the N-heterocyclic carbene ligand/PdCl2 catalyst for C C coupling reaction of aryl
iodides and organobismuths at room temperature. The established catalytic system exhibited high cross-
coupling reactivity between a variety of orgnobismuths and aryl iodides in the presence of K2CO3 as
base in NMP or DMSO at room temperature. The simple and efficient transformation can tolerate either
electron-withdrawing or electron-donating functional groups. It was notably found that both aryl bro-
mide and aryl chloride generated moderate to good yields of the corresponding biphenyl products using
3
0 September 2017
Accepted 3 October 2017
Available online 6 November 2017
5
mol% of PPh3/ligand 5 (1:1) as catalyst.
Keywords:
©
2017 Elsevier B.V. All rights reserved.
N-Heterocyclic carbene
Triarylbismuths
Cross-coupling
Catalyst
Palladium
1
. Introduction
The palladium catalyzed cross-coupling reactions is one of
catalyzed cross-coupling reaction between the aryl iodides and
ꢀ
◦
triarylbismuths by the addition of 2,2 -biquinoline in 120 C [11].
In 2010, Maddali L. N. Rao established a catalytic protocol using
Pd(OAc) (Cy NH) system for the coupling reaction with a vari-
the most important reaction for C C bonds forming in syn-
thetic organic chemistry [1]. Aryl-aryl bond formation is one of
the most studied processes in cross-coupling chemistry such as
the Suzuki-Miyaura [2], Stille [3], and Hiyama coupling reac-
tions [4]. Recently, the use of bismuth-derived compounds as
alternative reagents for the cross-coupling has attracted increas-
ing attention [5–8]. Organobismuth compounds are emerging as
prospective organometallic green reagents for coupling reaction in
organi.synthesis due to low-level toxic, stable to air, and environ-
mentally benign nature.
2
2
2
◦
ety of triarylbismuth and aryl iodides under mild condition (35 C)
[12]. Then, he unravelled an unprecedented cross-coupling of tri-
arylbismuth reagents with aryl iodides under task specific Pd-Cu
◦
dual catalytic conditions in 2016 (Pd(OAc) /CuI, dppf, DMF, 90 C,
2
4 h) [13].
Although organobismuth compounds have been successfully
utilized for the cross-coupling reaction, the studies are scarce
in the literature for the palladium catalyzed cross-coupling of
organobismuth compounds with aryl halides. Thus, it is still desir-
able to develop inexpensive and efficient catalytic methods for the
cross-coupling reaction using organobismuth reagents at the room
temperature. As far as we know, N-heterocyclic carbenes (NHCs)
have been extensively studied in the field of organometallics as
ligands comparable to the conventional phosphine ligands capa-
ble of coordination with a wide range of transition metals [14].
N-heterocyclic carbenes (NHCs) are now regarded as an efficient
catalyst as possible alternatives to pd–phosphine systems in the
cross-coupling reaction [15]. Some highly active palladium sys-
tems with N-heterocyclic carbene ligands for the activation of aryl
The known palladium catalyzed cross-coupling reaction of
◦
organobismuth compounds were performed under 80–130 C con-
ditions with aryl halides [9,10]. Several protocols with a variety
of ligands and palladium based on phosphines and amines are
reported with promising reactivity in coupling reactions. For
example, Yasunari Monguchi reported that a ligand-free 10% Pd/C-
∗ Corresponding author at: The School of Chemical and Material Science, Shanxi
Normal University, No. 1, Gongyuan Street, Linfen, 041004, China.
E-mail address: wangjunwen2013@126.com (J.-W. Wang).
http://dx.doi.org/10.1016/j.mcat.2017.10.004
2
468-8231/© 2017 Elsevier B.V. All rights reserved.

1
26
J.-Q. Liu et al. / Molecular Catalysis 443 (2017) 125–130
to give the pure title compound 4. 1H NMR (600 MHz, CDCl3,
25 C): 7.04 (d, 1H, J = 2.16 Hz), 7.00 (dd, 1H, J = 2.16, 8.23 Hz), 6.98
halides have been developed [16]. In 2016, C. Pichon reported
◦
the first cross-coupling reaction of Ar Bi with Ar’X mediated by
3
◦
Pd-NHC-PPh3 (ratio PEPPSI IPr/PPh : 1/1) in 90 C. Efforts were
(d, 1H, J = 8.23 Hz), 4.42 (s, 2H), 4.34–4.37 (m, 4H), 3.90–3.92 (t,
3
4H, J = 4.33 Hz) ppm. 13C NMR (125 MHz, CDCl , 25 C): ı = 150.41,
◦
focussed on the rule of each additive such as PPh3 and the base.
It was notably found that the presence of PPh3 was essential to
keep the process efficient [17]. In this paper, we report the mod-
ular synthesis of an imidazolium salts based on benzo-9-crown-3
and a practical and efficient method for the cross-coupling reaction
of aryl iodides with organobismuth catalyzed by N-heterocyclic
carbene-PdCl2 at the room temperature.
3
150.09, 132.30, 123.68, 122.72, 122.07, 73.12, 72.82, 71.29, 71.23,
32.13 ppm. Anal. Calcd for C11H13O Br: C, 48.37; H, 4.80. Found: C,
3
48.39; H, 4.78%.
2.2.4. Preparation of imidazolium salt ligand (5)
A
solution
of
4
(4.1 g,
15.1 mmol)
and
1-(9-
anthracenylmethyl)imidazole (3.89 g, 15.1 mmol) in THF (60 mL)
was stirred and refluxed for three days, a yellow precipitate was
formed. The raw imidazolium salt was purified by recrystallization
with DMF and water. NH4PF6 (2.46 g, 15.1 mmol) was added to a
DMF (15 mL) solution of the obtained imidazolium salt, then water
(30 mL) was added the DMF solution, and a yellow precipitate
formed immediately. The pure imidazolium salt was obtained by
recrystallization with CH2Cl2 and ethyl ether. Yield: 8.1 g (90%).
2
. Experimental section
2.1. General procedures
The compounds PdCl (CH CN) and Ar Bi were prepared
2
3
2
3
according to literature methods. All manipulations were performed
using Schlenk techniques, and solvents were thoroughly dried and
deoxygenated by standard methods. All reagents were obtained
from commercial sources and used without further purification.
NMR spectra were obtained on a Bruker Avance III HD 600 MHz
spectrometer. The chemical shifts are expressed in ppm and are
internally referenced. Positive-ion mass spectra were recorded by
1
◦
H NMR (600 MHz, DMSO-d6, 25 C): 9.08 (s, 1H), 8.85 (s, 1H), 8.46
(d, 2H, J = 8.85 Hz), 8.24 (d, 2H, J = 8.32 Hz), 7.74 (s, 1H), 7.61–7.69
(m, 5H), 6.94–6.97 (m, 2H), 6.90 (dd, 1H, J = 2.12, 8.22 Hz), 6.49 (s,
2H), 5.18 (s, 2H), 4.26 (t, 2H, J = 4.36 Hz), 4.24 (t, 2H, J = 4.36 Hz),
3.79 (m, 4H) ppm.; 13C NMR (125 MHz, DMSO-d6, 25 C): ı = 44.94,
◦
1
Bruker Impact II. All products were characterized by their H NMR
and C NMR that were identical to those in the literature.
51.07, 71.65, 72.87, 122.34, 122.47, 122.85, 122.86, 123.20, 123.23,
13
125.51, 127.68, 127.73, 129.33, 129.88, 130.06, 130.54, 131.00,
+
1
35.56, 150.98, 151.21 ppm; HRMS (QTOF) m/z: [M] Calcd for
+
2.2. Synthesis of imidazolium salt ligand (5)
C29H27N O 451.2016; found 451.2021.
2
3
2
.2.1. Preparation of 4-aldehyde-benzo-9-crown-3 (2)
Aldehyde 1 (18.0 g, 74 mmol) was added to a suspension of pow-
2.3. Typical procedure for the cross-coupling between
triarylbismuths and aryl iodedes
dered K CO (20 g, 147 mmol) in DMF (500 mL). After stirring under
2
3
◦
Ar at 90 C for 24 h, the mixture was filtered and the solvent was
evaporated in vacuo. The residues were poured into water, the
aqueous phase was extracted with CH Cl , washed with brine and
In a typical run, a mixture of PdCl2(CH3CN)2 (3 mol%), triaryl-
bismuths (0.195 mmol), aryl iodides (0.45 mmol), base (1.8 mmol),
ligand (5 mol%), solvent (2 mL) was stirred at room temperature
for 24 h under nitrogen. After the reaction time, the contents were
quenched with 15 mL water and extracted with dichloromethane.
The combined organic extract was washed with brine (15 mL) and
dried over anhydrous MgSO4, filtered, and concentrated under vac-
uum. The crude product was purified by column chromatography
to afford biaryl compounds.
2
2
dried with MgSO . The combined organic phase was concentrated
4
under vacuum. The crude product was purified by column chro-
matography (SiO ; hexanes: EtOAc 2:1) to afford the pure product
2
1
◦
2
9
8
2
2
7
(7.0 g, 45%) as a white solid. H NMR (600 MHz, CDCl , 25 C):
3
.81 (s, 1H) 7.52 (d, 1H, J = 1.93 Hz), 7.47–7.49 (dd, 1H, J = 1.93,
.28 Hz), 7.04 (d, 1H, J = 8.28 Hz), 4.61 (t, 2H, J = 4.26 Hz), 4.26 (t,
13
H, J = 4.36 Hz), 3.86–3.91 (m, 4H) ppm; C NMR (125 MHz, CDCl3,
◦
5 C): ı = 189.41, 155.86, 150.17, 130.88, 125.75, 123.88, 121.32,
3. Results and discussion
4.19, 71.67, 70.95, 70.65 ppm. Anal. Calcd for C11H12O : C, 63.45;
4
H, 5.81. Found: C, 63.50; H, 5.75%.
The synthetic routes of the NHC-benzo-crown ether ligand
(5) were demonstrated in Scheme 1. Compound 1 was readily
2
.2.2. Preparation of 4-methanol-benzo-9-crown-3 (3)
obtained by the alkylation of 3,4-dihydroxybenzaldehyde and an
excess of bis(2-chloroethyl) ether as described in previous lit-
erature [18]. We investigated synthetic strategy for preparing a
mono-imidazolium salt based on benzo-9-crown-3. Cyclization of
Aldehyde 2 (5.0 g, 24 mmol) was dissolved in MeOH (80 mL), the
◦
resulting solution was cooled to 0 C and NaBH (1.8 g, 48 mmol)
was added in batches. The resulting colourless solution was stirred
at room temperature for 2 h, when it was poured into water
4
1, carried out by base K CO3 in DMF, yielded 4-aldehyde-benzo-9-
2
(
100 mL). The mixture was extracted with CH Cl2 (200 mL). The
2
combined organic layers were dried (MgSO ), filtered, and concen-
4
trated in vacuo to afford the title compound 3 (4.8 g, 95%) as a white
solid. 1H NMR (600 MHz, CDCl , 25 C): 6.97 (s, 1H), 6.90 (d, 2H,
◦
3
J = 1.59 Hz), 4.61 (s, 2H), 4.18–4.20 (m, 4H), 3.90–3.92 (m, 4H) ppm.
13
◦
C NMR (125 MHz, CDCl , 25 C): ı = 151.33, 150.75, 137.04,
3
1
22.93, 122.59, 121.53; 74.13, 74.00, 72.49, 72.46, 64.57 ppm. Anal.
Calcd for C11H14O : C, 62.85; H, 6.71. Found: C, 62.84; H, 6.73%.
4
2.2.3. Preparation of 4-bromomethyl-benzo-9-crown-3 (4)
Crude alcohol 3 (4.8 g, 23 mmol), CBr4 (11.5 g, 35 mmol) were
dissolved in CH Cl (200 mL), PPh3 (9.1 g, 35 mmol) was added
2
2
in one portion. The reaction mixture turned to a dark orange
solution, which was stirred at room temperature for 5 h. The mix-
ture was concentrated under reduced pressure to afford a dark
orange oil, which was purified by FC (SiO : hexane/EtOAc 3:1)
Scheme 1. Synthesis of NHC ligand 5.
2

J.-Q. Liu et al. / Molecular Catalysis 443 (2017) 125–130
127
Table 1
Optimization of reaction conditions for the cross-coupling of 4-iodonirtobenzene with BiPh3.
◦
Yield (%)a
Entry
Solvent
Base
Loading of ligand
Loading of
Temp( C)
Time (h)
5
(mol%)
PdCl2(CH3CN)2 (mol%)
1
2
3
4
5
6
7
8
9
DMF
DMF
DMF
DMF
DMF
DMF
DMF
Acetone
THF
KOH
KOAc
5
5
5
5
5
5
5
5
5
5
5
5
5
1
2
3
4
8
3
3
3
3
3
3
3
3
3
3
3
3
3
1
2
3
3
3
90
90
90
90
90
90
25
25
25
25
25
25
25
25
25
25
25
25
5
5
5
5
5
5
24
24
24
24
24
24
24
24
24
24
24
24
30
40
44
41
50
60
70
21
29
25
95
85
15
65
71
85
90
95
K3PO4
Na3PO4
Na2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
1
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
8
Dioxane
DMSO
NMP
t
NMP
KO Bu
DMSO
DMSO
DMSO
DMSO
DMSO
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
a
Isolated yield based on an aryl iodide.
Table 2
The cross-coupling reaction of triarylbismuths and aryl iodides with electron-
withdrawing group.
Entry
Products
R1
R2
Yield (%)a
b
1
2
3
4
5
6
7
8
9
6a
6b
6c
6d
6e
6f
6g
6h
6i
4-NO2
4-NO2
4-NO2
4-CN
4-CN
4-CN
4-Ac
4-Ac
4-Ac
2-CN
2-CN
4-OCH3
H
95 (75 )
b
4-CH3
4-OCH3
H
4-CH3
4-OCH3
H
4-CH3
4-OCH3
4-OCH3
2-CN
H
94 (72 )
b
90 (69 )
b
89 (73 )
b
85 (73 )
b
80 (70 )
b
93 (70 )
b
90 (69 )
Fig. 1. X-Ray crystal structure of imidazolium salt 5. Atomic displacement parame-
ters obtained at 293 K are drawn at the 30% probability level.
b
86 (65 )
10
11
12
6j
6k
7a
85
86
72
crown-3 (2), TLC monitoring shows that an appropriate reaction
time for 48 h. Purification of the crude product from the reac-
tion mixture using silica-gel chromatography afforded the product
in 45% yield [19–21]. The aldehyde 2 was reduced following
by NaBH4 in methanol to give 4-methanol-benzo-9-crown-3 (3),
which brominated to mono-bromide 4, and subsequently trans-
formed into mono-imidazolium salt 5.
a
Isolated yield base on an aryl iodides, using 5 mol% ligand 5.
Isolated yield base on an aryl iodides, using 5 mol% ligand 6.
b
It is noteworthy that the desired product was obtained in 60% yield
using the base K CO3 in DMF at 90 C (Table 1, entry 6). Encour-
◦
2
agingly, this cross-coupling reaction was founded to be effective
even at room temperature in 70% yield (Table 1, entry 7). Lower
reaction temperature led to higher yield. This might be attributed
to the reduction of by-products of biphenyl from BiPh3 and homo-
coupled product from aryl iodide at room temperature. Therefore,
the base K CO was proven to be effective in DMF at room temper-
ature. Among the solvents tested, the cross-coupling product was
poor in THF, acetone and 1,4-dioxane (Table 1, entries 8–10). How-
ever, excellent yields were obtained when the solvent was changed
to DMSO or NMP (Table 1, entries 11–12). Under the best con-
ditions described in Table 1, the reaction afforded a 95% isolated
yield of 4-nitrobiphenyl by employing 5 mol% of ligand 5, 3 mol% of
PdCl (CH CN) , 4 equiv K CO in DMSO at room temperature for
The structure of ligand 5 was established by 1H NMR, 13C NMR,
1
and X-ray. H NMR spectra of 5 in DMSO-d , the proton peak
6
from the imidazolium (NCHN) was observed at 9.08 ppm, which
is consistent with the chemical shifts of known imidazolium salts
[
3
22]. The signals of salt 5 displays three resonances at 4.26, 4.24,
.79 ppm for the CH O-ether groups, which reveal the molecular
2
3
2
asymmetry. Yellow single crystals of salt 5 were obtained by a solu-
tion of diethyl ether and acetonitrile at room temperature (Fig. 1).
The crystals belong to the monoclinic space group P21/c, and the X-
ray structure was determined at 293 K. The benzene and anthracene
ring are respectively positioned on both sides of the imidazole ring,
◦
the dihedral angel of the two rings with imidazole ring are 87.9 and
2
3
2
2
3
◦
8
3.5 , respectively.
24 h (Table 1, entry 11).
The initial reaction conditions were optimized using 4-
Using optimized conditions, the cross-coupling scope and gen-
erality of a variety of aryl iodides with different triarylbismuths
was investigated in DMSO at room temperature (Table 2). The
presence of an electron-withdrawing group of aryl iodide is tol-
erated. As shown in Table 2 (entries 1–11), electron-withdrawing
substituents on the aryl iodide gave higher yields of isolated pure
compound at room temperature. Besides, electron-donating sub-
stituents on the triarylbismuths result in slightly lower yields.
It has been suggested that the presence of an electron-donating
group of triarylbismuths is favourable to increase side products
of biaryl from triarylbismuths. Unfortunately, a substrate with an
iodonitrobenzene and triphenylbismuth as the model substrates
under different bases, solvent, and temperature conditions (Table 1,
entries 1–18). As shown in Table 1, when 4-iodonitrobenzene
(
1 equiv) was stirred with BiPh3 (0.43 equiv) in presence of
◦
PdCl (CH CN) , ligand 5 and different bases in heated DMF (90 C),
2
3
2
the corresponding 4-nitrobiphenyl was obtained in 30–60% yields
Table 1, entries 1–6). The catalytic activity of 5 is highly dependent
(
on bases. Among the several bases examined, the use of KOH, KOAc,
◦
K PO , Na PO and Na CO3 as the bases in DMF at 90 C gave 4-
3
4
3
4
2
nitrobiphenyl in about 30–50% yields after 5 h (Table 1, entries 1–5).

1
28
J.-Q. Liu et al. / Molecular Catalysis 443 (2017) 125–130
Table 3
The cross-coupling reaction of triarylbismuths and 4-iodoanisole.
Table 4
The cross-coupling reaction of triarylbismuths and aryl iodides with electron-
donating group.
◦
Yield (%)a
Entry
Solvent
Base
Temp ( C)
Time (h)
Entry
Products
R1
R2
Yield (%)a
1
2
3
4
5
7
8
9
DMSO
DMF
NMP
DMA
DMSO
DMF
NMP
NMP
DMSO
THF
K2CO3
K2CO3
K2CO3
K2CO3
K3CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
90
90
90
90
50
50
50
25
25
25
5
5
5
5
56
61
70
51
65
61
76
91
72
29
1
2
3
4
5
6
7
8
9
7a
7b
7c
7d
7e
7f
7g
7f
7h
7i
7j
7k
7l
7l
6j
4-OCH3
4-CH3
3-NH2
4-NH2
4-CH3
4-OCH3
3-NH2
4-CH3
4-OCH3
3-NH2
4-NH2
4-OCH3
2-OCH3
2-CH3
H
H
H
H
CH3
CH3
CH3
OCH3
OCH3
OCH3
OCH3
H
91
93
90
89
90
85
80
86
84
83
83
84
82
80
87
5
12
12
24
24
24
1
1
0
1
1
1
1
1
1
1
0
1
2
3
4
5
a
Isolated yield base on an aryl iodides.
2-CH3
4-OCH3
2-CN
electron-donating group at the para-position of aryl iodide did not
afford the corresponding biaryl in high yield because of the com-
petitive and intercurrent homo-coupling of 4-iodoanisole (Table 2,
entry 12, 72% yield). So, we commenced our studies by examin-
ing the effects of various reactions parameters on the yield of this
cross-coupling using 4-iodoanisole and triphenylbismuth. After the
Pd-NHC was shown to be an effective catalyst for the cross-coupling
of aryl iodides and triarylbismuths, the ligand 6 was also pre-
pared for comparison. This imidazolium salt 6 was then compared
with NHC-benzo-crown ether ligand 5 in standard cross-coupling
forming biaryls (Table 2, entries 1–9). It was worth noting that
both precursors gave comparable reaction yields under optimized
reaction conditions of cross-coupling aryl iodides and triarylbis-
muth. It is surprising that ligand 5 seems to have a large impact
on the coupling (Table 2, entries 1–9). Palladium complexes with
the supermolecular NHC ligands have been studied previously and
shown to be efficient in Suzuki-Mayarua cross coupling reaction
4-OCH3
a
Isolated yield base on an aryl iodides.
Scheme 2. Proposed mechanism cycle for the cross-coupling reaction.
different triarylbismuths and various aryl iodides (Table 4). Using
the NHC-benzo-9-crown-3 ligand 5, PdCl (CH CN) as the catalyst
2
3
2
and K CO3 as the base, the cross-coupling reactions of aryl iodides
2
and triarylbismuths were carried out in NMP at room temperature.
The cross-coupling reactivity with aryl iodides with electron donat-
ing was found to be efficient even with a lower palladium catalyst
[
23–25]. For example, Luo M. group reported palladium (II)-NHC
(3 mol%) loading (Table 4, entries 1–15) at room temperature. The
Metallacrown Ether Complexes in 2009 [24]. We have prepared
the NHC ligand based porphyrins and metallacrown ether scafford,
and discussed the catalytic activity of Suzuki coupling [25]. The
crownether-based imidazolium salt is promising for the construc-
tions of highly active supramolecular catalytic systems.
reactions of electron-rich p-methyl, p-methoxy and p-amino sub-
stituted iodophenyl gave high yields of the cross-coupling products.
In general, strong electron-donating substituents on the aryl iodide
or triarylbismuths result in lower slightly yields.
The Pd–NHC was show to be an effective catalyst for the cross-
coupling of triarylbismuths and aryl iodides. Despite the lower
reactivity of aryl chlorides and bromides compared with the cor-
responding aryl iodides. Aryl chlorides and bromides are the most
desirable substrates because of their lower cost and ready availabil-
ity. Here, we have performed the reaction of triarylbismuths with
aryl bromides and chlorides in order to extend scope and define
limitation of our strategy (Table 5). Unfortunately, in our system,
the ligand 5 only demonstrated a low level of catalytic activity com-
pared with aryl iodides at room temperature (entries 1 and 5), but
The model reaction was also tested under the reaction con-
ditions used in the synthesis of 4-methoxylbiphenyl (5 mol%) of
ligand 5, 3 mol% of PdCl (CH CN) , 4 equiv K CO and the results
2
3
2
2
3
are summarized in Table 3. In the current studies, we usually inves-
tigated the effect of solvent and reaction temperature on the model
reaction. Among the solvents examined, DMSO was afforded mod-
erate yield (72%), regardless of the reaction temperature (Table 3,
entries 1, 5 and 10). NMP was found to be the best solvent, and the
yields increase with the decrease of reaction temperature (Table 3,
entries 3, 8 and 9). The nature of the initial precatlayst, solvent
and base is crucial for the success of the cross-coupling reaction,
especially. Electron-withdrawing substituents on the aryl iodide
gave higher yields of isolated pure compound in DMSO at room
temperature. Besides, electron-donating substituents on the tri-
arylbismuths result in slightly lower yields. It has been suggested
that the presence of an electron-donating group of aryl iodides
is favourable to increase side products of biaryl from aryl iodides
in DMSO. We found that the substrate with an electron-donating
group underwent the reaction smoothly to furnish the correspond-
ing biaryl in higher yield and minimized side products in NMP
at room temperature. Using NMP as solvent led to higher yield.
This might be attributed to the reduction of by-products from
homo-coupling of aryl iodide at room temperature. Therefore, the
optimal catalytic system involved the use of ligand 5 (5 mol%),
PdCl (CH CN) (3 mol%), K CO3 (4 equiv) in NMP at room temper-
◦
showed higher activities in 90 C (entries 4 and 8). When 5 mol%
of PPh /ligand 5 (1:1) were employed in cross-coupling reaction at
3
room temperature, both aryl bromide and aryl chloride generated
moderate to good yields of the corresponding biphenyl products
(Table 5, entries 3 and 7). It was notably found that the presence of
PPh3 was essential to keep the process efficient. The hypothesis of
the reaction mechanism has been described in reference (Scheme 2)
[
17].
4. Conclusions
In summary, we have developed an efficient reaction of aryl
iodides and triarylbismuths catalyzed by N-heterocyclic carbene-
PdCl2 based on benzo-9-crown-3 at room temperature. Aryl
iodides bearing an electron-withdrawing or electron-donating
group underwent the reaction smoothly to furnish the correspond-
ing biaryl in high yields in NMP or DMSO by combined use of
imidazolium salt 5 with K CO as ligand and base, respectively. The
2
3
2
2
ature for 24 h.
The scope of this cross-coupling reaction of triarylbismuths and
aryl iodides with electron-donating group was also established by
2
3

J.-Q. Liu et al. / Molecular Catalysis 443 (2017) 125–130
129
Table 5
The cross-coupling reaction of triarylbismuths and aryl chloride and bromide.
◦
Yield (%)a
Entry
X
R
Solvent
Loading of ligand
X mol%)
Loading of PPh3
(X mol%)
Temp ( C)
(
1
2
3
4
5
6
7
8
Br
Br
Br
Br
Cl
Cl
Cl
Cl
NO2
NO2
NO2
NO2
CH3
CH3
CH3
CH3
DMSO
DMSO
DMSO
DMSO
NMP
NMP
NMP
NMP
5
0
5
5
5
0
5
5
0
5
5
0
0
5
5
0
25
25
25
90
25
25
25
90
15
20
90
76
40
10
85
66
a
Isolated yield base on an aryl iodides.
transformation can tolerate either electron-donating or electron-
(e) N.T.S. Phan, M.V.D. Sluys, C.W. Jones, Adv. Synth. Catal. 348 (2006)
09–679.
2] (a) J.W.B. Fyfe, N.J. Fazakerley, A.J.B. Watson, Angew. Chem. Int. Ed. 56 (2017)
249–1253;
(b) M. Mohadjer, B. Ainara, N. David, B. Ann, M.B. Gary, W.B. Louise, M.G.
Nilay, H. David, J. Vinyard, J. Am. Chem. Soc. 139 (2017) 922–936;
6
withdrawing functional groups. When 5 mol% of PPh /ligand 5 (1:1)
3
[
were employed in cross-coupling reaction at room temperature,
both aryl bromide and aryl chloride generated moderate to good
yields of the corresponding biphenyl products. This exploration is
expected to have great applications in organic synthesis.
1
(
c) C. Valente, S. C¸ alimsiz, K.H. Hoi, D. Mallik, M. Sayah, M.G. Organ, Angew.
Chem. Int. Ed. 51 (2012) 3314–3332;
d) J.W. Wang, Q.S. Li, F.B. Xu, H.B. Song, Z.Z. Zhang, Eur. J. Org. Chem. (2006)
310–1316;
(
1
4.1. X-ray structure crystallography
(
(
f) A.F. Littke, C. Dai, G.C. Fu, J. Am. Chem. Soc. 122 (2000) 4020–4028;
g) N.T.S. Phan, M.V.D. Sluys, C.W. Jones, Adv. Synth Catal. 348 (2006)
6
09–679.
3] (a) S. Lindner, M. Nieger, S. Bräse, Adv. Synth. Catal. 357 (2015) 3303–3308;
b) S.M. Rummelt, J. Preindl, H. Sommer, A. Fürstner, Angew. Chem. Int. Ed. 54
(2015) 6241–6245;
(c) A.G. Choghamarani, A.A. Derakhshan, M. Hajjami, L. Rajabi, RSC Adv. 6
Crystals of 5 suitable for X-ray diffraction analysis were grown
[
[
from layering a saturated CH CN and chlorobenzene solution with
3
(
diethyl ether. Suitable crystals of 5 were mounted on a glass fiber in
a random orientation. The structures were solved by direct methods
and all nonhydrogen atoms were subjected to anisotropic refine-
ment by full-matrix least squares on F2 using the SHELXTL package.
Data collection was performed at room temperature on a Bruker
SMART 1000 CCD diffractometer operating at 50 kV and 20 mA
using Mo-Ka radiation (0.71073 Å). An empirical absorption correc-
tion was applied using the SADABS program. All hydrogen atoms
were generated geometrically (C H bond lengths fixed at 0.96 Å),
assigned appropriated isotropic thermal parameters and included
in structure factor calculations.
(
(
(
2016) 94314–94324;
d) E. Palao, T. Slanina, P. Klán, Chem. Commun. 52 (2016) 11951–11954;
f) E.A. Ziemann, S. Baljak, S. Steffens, T. Stein, N.V. Steerteghem, I.
Asselberghs, K. Clays, J. Heck, Organometallics 34 (2015) 1692–1700.
4] (a) Y. Wu, H.-R. Zhang, Y.-X. Cao, Q. Lan, X.-S. Wang, Org. Lett. 18 (2016)
5
(
564–5567;
b) G.C.E. Raja, F.M. Irudayanathan, H.-S. Kim, J. Kim, S. Lee, J, Org, Chem. 81
(2016) 5244–5249;
c) S. Modak, M.K. Gangwar, M.N. Rao, M. Madasu, A.C. Kalita, V. Dorcet, M.A.
Shejale, R.J. Butcher, P. Ghosh, Dalton Trans. 44 (2015) 17617–17628;
d) S.-H. Huang, C.-H. Liu, C.-M. Yang, Green Chem. 16 (2014) 2706–2712.
(
(
[5] (a) M.L.N. Rao, O. Yamazaki, S. Shimada, T. Tanaka, Y. Suzuki, M. Tanaka, Org.
Lett. 25 (2001) 4103–4105;
(
b) M.L.N. Rao, D.N. Jadhav, D. Banerjee, Tetrahedron 64 (2008) 5762–5772;
Acknowledgements
(c) M.L.N. Rao, R.J. Dhanorkar, RSC Adv. 4 (2014) 13134–13144.
6] (a) M.L.N. Rao, D. Banerjee, D.N. Jadhav, Tetrahedron Lett. 48 (2007)
[
2
(
707–2711;
b) S. Shimada, O. Yamazaki, T. Tanaka, M.L.N. Rao, Y. Suzuki, M. Tanaka,
Angew. Chem. Int. Ed. 42 (2003) 1845–1848;
c) C. Xu, L. Yin, B. Huang, H. Liu, M. Cai, Tetrahedron 72 (2008) 2065–2071.
7] (a) R.J. Dhanorkar, RSC Adv. 3 (2013) 6794–6798;
This work is supported by the Research Fund for the Edu-
cation Department of Shanxi Province (No. 2010111), and the
Shanxi Natural Science Foundation of China for the project (No.
(
[
[
2
011011006-4).
(
(
b) M.L.N. Rao, D.N. Jadhav, P. Dasgupta, Eur. J. Org. Chem. (2013) 781–788;
c) M.L.N. Rao, D.N. Jadhav, P. Dasgupta, Org. Lett. 12 (2010) 2048–2051.
8] (a) M.L.N. Rao, D. Banerjee, S. Giri, J. Organomet. Chem. 695 (2010)
518–1525;
b) W.-J. Zhou, K.-H. Wang, J.-X. Wang, D.-F. Huang, Eur. J. Org. Chem. (2010)
16–419.
9] (a) A. Gagnon, J. Dansereau, A.L. Roch, Synthesis 49 (2017) 1707–1745;
b) M. He ı´ bert, P. Petiot, E. Benoit, J. Dansereau, T. Ahmad, A.L. Roch, X.
Ottenwaelder, A. Gagnon, J. Org. Chem. 81 (2016) 5401–5416;
c) P. Kutudila, R. Linguerri, M. Mogren, A. Mogren, C. Pichon, S. Condon, M.
Hochlaf, Theor. Chem. Acc. 135 (2016) 176;
d) C.F. Xu, L. Yin, B. Huang, H.Y. Liu, M.Z. Cai, Tetrahedron 72 (2016)
2065–2071.
[10] (a) M.L.N. Rao, R.J. Dhanorkar, Eur. J. Org. Chem. (2014) 5214–5228;
Appendix A. Supplementary data
1
(
4
Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.mcat.2017.10.
[
(
004.
(
Crystallographic data for the structure reported in this paper has
been deposited with the Cambridge Crystallographic Data Center:
CCDC-714292 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre, www.ccdc.cam.ac.uk/
datarequest/cif.
(
(b) P. Petiot, A. Gagnon, Eur. J. Org. Chem. (2013) 5282–5289;
(c) S. Shimada, M.L.N. Rao, Top. Curr. Chem. 311 (2012) 199–228;
(d) R. Chaudhari, A.P. Wadawale, V.K. Jain, J. Organomet. Chem. 698 (2012)
1H and 13C NMR Spectra of Products
X-ray crystallographic data for compound 5 (CIF)
15–21;
(
(
e) M.L.N. Rao, D.N. Jadhav, V. Venkatesh, Eur. J. Org. Chem. (2010) 4300–4306;
f) M.L.N. Rao, D. Banerjee, D.N. Jadhav, Tetrahedron Lett. 48 (2007)
6644–6647;
(
g) M.L.N. Rao, O. Yamazaki, S. Shimada, T. Tanaka, Y. Suzuki, M. Tanaka, Org.
References
Lett. 3 (2001) 4103–4105.
[
[
11] Y. Monguchi, T. Hattori, Y. Miyamoto, T. Yanase, Y. Sawama, H. Sajikia, Adv.
Synth. Catal. 354 (2012) 2561–2567.
12] M.L.N. Rao, D. Banerjee, R.J. Dhanorkar, Tetrahedron Lett. 51 (2010)
[
1] (a) S. Mattiello, M. Rooney, A. Sanzone, P. Brazzo, M. Sassi, L. Beverina, Org.
Lett. 19 (2017) 654–657;
(
(
(
b) V. Sable, K. Maindan, A.R. Kapdi, P.S. Shejwalkar, K. Hara, ACS Omega 2
2017) 204–217;
c) C.C.C.J. Seechurn, M.O. Kitching, T.J. Colacot, V. Snieckus, Angew. Chem. Int.
6101–6104.
[
[
13] M.L.N. Rao, R.J. Dhanorkar, RSC Adv. 6 (2016) 1012–1017.
14] (a) D. Pugh, A.A. Danopoulos, Coord. Chem. Rev. 251 (2007) 610–641;
Ed. 51 (2012) 5062–5085;
d) R. Rossi, F. Bellina, M. Lessi, Adv. Synth. Catal. 354 (2012) 1181–1255;
(
b) P.L. Arnold, I.J. Casely, Chem. Rev. 109 (2009) 3599–3611.
(

1
30
J.-Q. Liu et al. / Molecular Catalysis 443 (2017) 125–130
[
15] (a) T.B. Halima, W. Zhang, I. Yalaoui, X. Hong, Y.-F. Yang, K.N. Houk, S.G.
[19] (a) E. Luboch, A. Cygan, J.F. Blernat, Tetrahedron 46 (1990) 2461–2472;
(b) T. Bogaschenko, S. Basok, N.A. Lukyanenko, Synthesis 15 (2002)
2266–2270;
Newman, J. Am. Chem. Soc. 139 (2017) 1311–1318;
(
b) A. Ohtsuki, K. Yanagisawa, T. Furukawa, M. Tobisuand, N. Chatani, J. Org.
Chem. 81 (2016) 9409–9414;
(c) L. Yu, M. Ouchi, Y. Inoue, Bull. Chem. Soc. Jpn. 63 (1990) 1260–1262.
[20] M.F. Rastegar, M. Ghandi, M. Taghizadeh, A. Yari, M. Shamsipur, G.P.A. Yap, H.
Rahbarnoohi, A. Moghimi, J. Org. Chem. 67 (2002) 2065–2074.
[21] G.W. Buchanana, M.F. Rastegara, G.P.A. Yap, J. Mol. Struct. 561 (2001) 43–54.
[22] (a) X.-D. Xiao, Y.-L. Bai, J.-Q. Liu, J.-W. Wang, Tetrahedron Lett. 57 (2016)
3385–3388;
(b) X.-D. Xiao, L. Shi, L.-H. Guo, J.-W. Wang, X. Zhang, Spectrochim. Acta A 173
(2017) 6–12.
[23] (a) I. Dinarès, C.G. Miguel, F.B. Mercè, X. Solans, E. Alcalde, Organometallics 26
(2007) 5125–5128;
(b) J.S. Ürgen, B. Thomas, F. Markus, Eur. J. Org. Chem. (2006) 2378–2383.
[24] X. Zhang, Y. Qiu, B. Rao, M. Luo, Organometallics 28 (2009) 3093–3099.
[25] (a) J.W. Wang, F.H. Meng, L.F. Zhang, Organometallics 28 (2009) 2334–2337;
(b) J.-W. Wang, L.-Y. Gao, F.-H. Meng, J. Jiao, L.-Y. Ding, L.-F. Zhang, J. Incl.
Phenom. Macrocycl. Chem. 73 (2012) 119–128.
(
(
(
(
(
(
c) X. Ma, H. Wang, W. Chen, J. Org. Chem. 79 (2014) 8652–8658;
d) S. Ando, H. Matsunaga, T. Ishizuka, J. Org. Chem. 82 (2017) 1266–1272;
e) D. Wang, D. Astruc, Chem. Soc. Rev. 46 (2017) 816–854;
f) S. Gu, J. Du, J. Huang, Y. Guo, L. Yang, W. Xu, W. Chen, Dalton Trans. 46
2017) 586–594;
g) T. Begum, M. Mondal, M.P. Borpuzari, R. Kar, G. Kalita, P.K. Gogoi, U. Bora,
Dalton Trans. 46 (2017) 539–546;
h) L.-J. Gu, C. Jin, H.-T. Zhang, Chem. Eur. J. 21 (2015) 8741–8744.
16] (a) S. Roy, H. Plenio, Adv. Synth. Catal. 352 (2010) 1014–1022;
b) X.-Y. Xu, B.-C. Xu, Y.-X. Li, S.H. Hong, Organometallics 29 (2010)
343–6349;
c) D.R. Snead, S. Inagaki, K.A. Abboud, S.H. Hong, Organometallics 29 (2010)
729–1739;
d) C.-Y. Liao, K.-T. Chan, C.-Y. Tu, Y.-W. Chang, C.-H. Hu, H.M. Lee, Chem.–Eur.
(
[
(
6
(
1
(
J. 15 (2009) 405–417.
[
[
17] B. Cassirame, S. Condon, C. Pichon, J. Mol. Catal. A: Chem. 425 (2016) 94–102.
18] (a) A. Reitz, M.A. Avery, M.S. Verlander, M. Goodman, J. Org. Chem. 46 (1981)
4
(
859–4863;
b) J.-P. Bourgeois, P. Seiler, M. Fibbioli, E. Pretsch, F. Diederich, Helv. Chim.
Acta. 82 (1999) 1572–1595.