Synthesis, characterization and X-ray structures of N-heterocyclic carbene palladium complexes based on calix[4]arenes: Highly efficient catalysts towards Suzuki-Miyaura cross-coupling reactions

Article abstract of DOI:10.1016/j.tet.2014.02.051

A new series of calix[4]arene supported N-heterocyclic carbene palladium complexes were developed and fully characterized. A mono-substituted calix[4]arene was prepared through conventional procedures, following with the attachment of imidazolyl derivative groups to compose the precursors of novel NHCs ligands. Undergoing the alkylation with n-butylbromide and corresponding metallation with palladium and pyridine, original complexes were obtained. After a full characterization in solution and solid state, the evaluation of catalytic activity was taken out in Suzuki-Miyaura cross-coupling reactions, which revealed good performances.

Full text of DOI:10.1016/j.tet.2014.02.051

Tetrahedron 70 (2014) 2829e2837
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis, characterization and X-ray structures of N-heterocyclic
carbene palladium complexes based on calix[4]arenes: highly
efficient catalysts towards SuzukieMiyaura cross-coupling reactions
,
b,
Hui Ren a, Yong Xu b, Erwann Jeanneau a, Isabelle Bonnamour a , Tao Tu
*
*
,
,
Ulrich Darbost a
*
a
ꢀ
ꢀ
ꢀ
ꢀ
ICBMS UMR CNRS 5246, Equipe Chimie Supramoleculaire Appliquee, Universite de Lyon, Universite Lyon 1, 43 Boulevard du 11 Novembre 1918,
F-69622, Villeurbanne, France
b Department of Chemistry, Fudan University, 220 Handan Road, 200433 Shanghai, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A new series of calix[4]arene supported N-heterocyclic carbene palladium complexes were developed
and fully characterized. A mono-substituted calix[4]arene was prepared through conventional pro-
cedures, following with the attachment of imidazolyl derivative groups to compose the precursors of
novel NHCs ligands. Undergoing the alkylation with n-butylbromide and corresponding metallation with
palladium and pyridine, original complexes were obtained. After a full characterization in solution and
solid state, the evaluation of catalytic activity was taken out in SuzukieMiyaura cross-coupling reactions,
which revealed good performances.
Received 19 November 2013
Received in revised form 11 February 2014
Accepted 19 February 2014
Available online 28 February 2014
Keywords:
Calix[4]arene
N-Heterocyclic carbene
Palladium complex
Catalysis
Ó 2014 Elsevier Ltd. All rights reserved.
SuzukieMiyaura cross-coupling
1. Introduction
potential candidates as supramolecular catalysts. Thanks to an
interaction through the space, the presence of a well-defined
N-Heterocyclic carbenes (NHCs) and their transition metal
complexes have attracted increasing attention in recent years,1 due
to their wide applications in catalysis and material sciences. Nu-
merous NHC transition metal complexes were developed until now,
including metals such as Co,2 Pd,3 Cu4 and Ni.5 Among them,
complexes composed with NHCs and Pd constituted one of the
prominent representatives owing to their robustness against air,
moisture and heat, which also exhibited excellent catalytic activi-
ties in cross-coupling reactions.3cel
From the point of view of coordination chemistry, the calix[4]
arene skeleton displays essential advantages. Indeed, attaching
a set of podand arms on calixarene skeleton, leads to an attractive
platform for the design of sophisticated coordination spheres.6
Moreover, the calixarene core displays essential advantages fea-
tures such as preorganization,7 flexibility8 and its bulkiness skel-
eton,9 as well as its widely tolerance of functional groups and
metals. As a consequence, by tethering particular transition metals
on such structure, the new series compounds were predicted to be
cavity near the catalytic centre could induce selectivity in the re-
action. Furthermore, the calixarene scaffold could be used to in-
troduce specific features like chirality, fluorescence or hydro
solubilizating groups, which can be useful for the design of ver-
satile catalysts.
Following our recent research on developing novel metal com-
plexes and their potential application in catalysis and material
sciences,3k,5b,10aef,11 NHCs were prior selected to introduce into the
calix[4]arene skeleton for novel catalysts owe to their impressive
appearance in cross-coupling reactions, such as Suzuki coupling,
Heck and amination reactions, even at low catalyst loadings. To the
best of our knowledge, there is only a few examples of calixarene
supported NHC ligands described in the literature,4c,12 some of
them displaying good catalytic activities towards Suzuki coupling
reactions. Complementary studies were carried out by Dominique
Matt.13 In his research, imidazole was introduced to calix[4]arene
skeleton as a precursor of NHCs. Ultimately, a series of ligands with
direct combination between the upper rim of calix[4]arene and
NHCs through one of the nitrogen atoms was reported.13d,e The
evaluation of catalytic activity indicated that those compounds
display good performances as catalyst in Suzuki cross-coupling
reactions.
* Corresponding authors. E-mail address: Ulrich.darbost@univ-lyon1.fr (U.
Darbost).
0040-4020/$ e see front matter Ó 2014 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2014.02.051

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H. Ren et al. / Tetrahedron 70 (2014) 2829e2837
Despite the calix[4]arene cavity, adopting a well-defined cone
The NMR analysis was implemented after cross-coupling re-
actions with imidazole derivatives. The resonances of significant
protons NCHN from imidazole attest that the new precursors of
NHCs ligands were obtained. After subsequent alkylation, charac-
teristic peaks in range of 11.86e10.47 ppm showed up corre-
sponding to active protons, which is a convincing proof of
formation of bromides. Finally NHC palladium complexes were
obtained using conventional procedures: reaction of calixarenes
2ae4a with PdCl2 in pyridine at 80 ꢀC in presence of K2CO3 and KBr
afforded the NHC complexes 2be4b (in 97%, 56% and 87% yields,
respectively). In addition, the reaction of 2a with quinoline or iso-
quinoline in dioxane in the same conditions gave the NHC com-
plexes 2c (41%) and 2d (74%), respectively. All those new structures
were purified through chromatography and characterized through
1D NMR such as: 1H NMR, 13C NMR and 2D NMR including: COSY,
HSQC, NOESY as well as HRMS.
conformation, it was demonstrated that there was no supramo-
lecular effect involved with the reported complexes. Indeed, due to
bulkiness reasons, NHC complexes are constrained in an ‘out’
conformation, meaning that the PdX2L moiety is oriented towards
the outside of the cavity.
With the aim to evaluate the influence of changing the nature of
the N-heterocyclic carbene on the conformation and also on the
catalytic activity, new calix[4]arene-supported NHCs palladium
complexes were developed and investigated. The new compounds
were synthesized, fully characterized and their potential catalytic
activities towards SuzukieMiyaura cross-coupling reactions were
also evaluated at low catalyst loadings.
2. Results and discussion
2.1. Synthesis and characterization
2.2. Conformational study
As illustrated in Scheme 1, a series of calixeNHC palladium
complexes were prepared in three steps. The starting mono-
bromide calix[4]arene 1, a key intermediate, was obtained in
a 79% overall yield according to literature procedure.13a Then, an
Ullmann type coupling in the presence of CuI/DMEDA and Cs2CO3
in DMF, allows to introduce imidazolyl, triazolyl and benzimida-
zolyl groups on the wide rim of the calix[4]arene. The original
compounds 2, 3 and 4 were, respectively, synthesized in 73%, 57%
and 56% yields and were alkylated with n-BuBr in excess, resulting
in salts 2a (88% yield), 3a (40% yield) and 4a (87% yield),
respectively.
The 13C NMR spectra of all the calixarene derivatives 2e4 and
2ae4a indicated that ArCH2Ar signals appeared at the range
32.3e30.8 ppm and their 1H NMR spectra revealed two AB patterns
for the diastereotopic ArCH2Ar protons, both observations dem-
onstrating that the backbone of these calixarene derivatives are in
cone conformation. Its interesting to note that particular reso-
nances around 10 ppm demonstrate the presence of acidic protons
in 2ae4a, which conduces to the composition of NHCs.
New complexes 2b, 3b and 4b were fully characterized. All
resonances were well attributed with the contribution of 1D and 2D
N
R1
R1
N
N
Br
N
H
Cs2CO3, CuI,
DMEDA, DMF
180oC, 7days
PrO
OPr
OPr
OPr
PrO
OPr
OPr
OPr
1
2: 73%, R1=H
3: 57%, R1=1H,2,4-triazole
4: 56%, R1=1H-benzimidazole
nBuBr reflux, 24h
Bun
Bun
N
N
R1
R1
Br
Pd
Br
N
N
N
PdCl2,
K2CO3, KBr
R2
Br
i
Pyridine
or Quinoline
or Isoquinoline
PrO
PrO
OPr
OPr
OPr
OPr
OPr
OPr
2b: 97%, R1=H, R2=H
2a: 88%, R1=H
2c: 41%, R1=H, R2=benzo[b]
2d: 74%, R1=H, R2=benzo[c]
3a: 40%, R1=1H,2,4-triazole
4a: 87%, R1=1H-benzimidazole
3b: 56%, R1=1H,2,4-triazole, R2=H
4b: 87%, R1=1H-benzimidazole, R2=H
Scheme 1. Synthesis of palladium complexes 2be2d, 3b and 4b.

H. Ren et al. / Tetrahedron 70 (2014) 2829e2837
2831
NMR (see details in Supplementary data). The 13C NMR spectra of
complexes 2ae4a show ArCH2Ar signals presence in the range of
32.0e29.7 ppm. In parallel, two AB patterns for the diastereotopic
ArCH2Ar protons appear in their 1H NMR spectra. Both phenomena
indicated that the scaffold of calixarenes is in cone conformation.
The signals range in 8.9e8.8 ppm corresponding to ortho-protons
from pyridine, the chelation between palladium and pyridine was
attested (Fig. 1). Through a NOESY experiment, it was also implied
that there is no correlation between pyridine and the skeleton of
calixarene, which suppose that no spatial interaction between
those moieties exist among 2b, 3b and 4b, indicating that all three
complexes are constrained in an ‘out’ conformation.
To our knowledge, those X-ray structures are the first examples
of crystallized monomeric calixeNHCePd complexes. In the solid
state, both the calixarene parts of complexes 2b and 4b display
a cone conformation, correlating with the observation made
through NMR analysis in solution media. The metallic centre adopts
a trans stereochemistry, with the following remarkable distances:
(respectively for 2b and 4b) PdeC 1.95(0) and 1.95(5), PdeN 2.09(5)
and 2.08(3), PdeBr 2.44(9)/2.42(0) and 2.44(3)/2.43(4). This co-
ordination fashion is classical and similar to the examples described
previously by D. Matt et al.13 In the case of 4b, its interesting to
notice that the NHC moiety of the edifice has a different orientation
through space compared to the 2b complex. Indeed, the dihedral
Fig. 1. Triple display of partial 1H NMR spectra (400 MHz, CDCl3) of complexes 2b, 3b and 4b.
2.3. X-ray structures
angle CArcalixeNImeCImeCIm of 4b is much more closed (52.3(4)ꢀ)
than the corresponding angle of 2b (82.5(8)ꢀ) (see Fig. 3). This ob-
servation could be rationalized with the establishment of a weak
Among many attempts of crystallisation, single crystals of the
compound 2b and 4b were obtained. An X-ray analysis revealed the
structures of the two monomeric species and confirmed the con-
clusions of solution analysis regarding the expected ‘out’ confor-
mation (Fig. 2).
CeH.p interaction between the benzimidazole and the proximal
aromatic ring of the calixarene H-Centroid 3.54(1). The lack of this
interaction in the case of 2b, leads the PdX2L being oriented as far as
possible from the calixarene, that is to say at almost a right angle.
2.4. SuzukieMiyaura cross-coupling
To study the efficiency of our new developed PdeNHC com-
plexes 2be4b in SuzukieMiyaura reactions, bromobenzene and 4-
methoxyphenyl boronic acid were selected as substrates to opti-
mize the reaction conditions (Table 1). Preliminary experiments
demonstrated that the same results were obtained with NHCePd
complexes and catalyst formed in situ. The activities observed with
our calixarene palladium complexes are similar to those of the Matt
complexes.13a
Fig. 2. X-ray structures of 2b (left) and 4b (right). Solvent of crystallization and counter
anions were omitted for clarity.

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H. Ren et al. / Tetrahedron 70 (2014) 2829e2837
Fig. 3. X-ray structures of 2b and 4b. Solvent of crystallization and counter anions were omitted for clarity. View of the dihedral angle CArcalixeNImeCImeCIm of 4b (a) and 2b (b).
Representation of the CeH.
p interaction between the benzimidazole and the proximal aromatic ring of the calixarene (c).
Table 1
Condition screening and optimizationa
Entry
Cat./mol %
Base
Solvent
Yieldb (%)
1
2
3
4
5
6
7
8
2b/1
3b/1
4b/1
4b/1
4b/1
4b/1
4b/1
4b/1
4b/0.1
4b/0.1
4b/0.1
4b/0.1
4b/0.1
4b/0.1
4b/0.08
4b/0.05
\
t-BuOK
t-BuOK
t-BuOK
KOH
K2CO3
KF
KOAc
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
\
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
DMA
DMF
DME
THF
Toluene
Dioxane
Dioxane
Dioxane
57
43
65
94
95
93
95
99
98
93
94
52
91
61
90
82
NR
9
10
11
12
13
14
15
16
17
a
1 mmol scale at 100 ꢀC for 24 h.
Isolated yield.
b
To our delight, a 65% isolated yield of the resulting product was
observed when t-BuOK was applied as base (Table 1, entry 3);
however, when catalysts 2b and 3b were applied, lower yields were
good to excellent isolated yields (>90%). Moreover, the relative
position of electron-deficient substituents hardly hindered the
coupling efficiency. Similar moderate yields were obtained with o-,
m- and p-bromotoluene, which revealed that steric substituents on
one side of the reacting partners did not influence the coupling
efficiency and electronic properties of the electrophiles hampered
the coupling process.
observed, which may attribute to stronger s-donor and weaker p-
acceptor properties of 4b. Simultaneously, other potassium bases
were selected for further optimization. It is interesting that all se-
lected weak potassium bases like K2CO3, KOAc, K3PO4 and another
strong base KOH accelerated the transformation and resulted in
similar satisfactory yields (90e99%, Table 1, entries 4e8). Further
decreasing the catalyst loading to 0.1 mol %, a similar excellent
isolated yield was afforded when K3PO4 and dioxane were used as
base and solvent (98% vs 99% Table 1, entries 8 and 9). With other
polar solvents, such as DMA, DMF and THF, instead of dioxane, the
coupling processes still work well and similar yields beyond 90%
were obtained (Table 1, entries 10, 11 and 13). However, the pres-
ence of DME and toluene as solvent obviously decreased the re-
action activity (Table 1, entries 12 and 13). Additionally, no
reactions occurred when selected organic bases were tested. In
contrast to the blank test, upon decreasing the catalyst loading to
0.08 mol % or 0.05 mol %, 90% and 82% yields were still obtained
when reactions were carried out in the presence of K3PO4 and di-
oxane (Table 1, entries 15 and 16), which further confirmed the
catalyst efficiency.
For the bulky substrates like 1,10-biphenyl-2-bromide and 1-
bromonaphthalene were applied, good to moderate yields were
still obtained. Further investigation of di-ortho-substituted bro-
mides afforded in a surprising outcome, in which anthracen-9-yl
bromide resulted in a much better yield than 2,6-dimethyl ana-
logue, which indicated that electronic properties influence is
greater than steric effects during the transformation and further
supported by the coupling outcomes of 1,10-biphenyl and naph-
thalenyl bromides.
When other heterocyclic substrates were applied, good to ex-
cellent results were observed, which can be further extended to the
coupling with heterocyclic substrates containing free NH group and
a moderate yield was obtained without any additional protection
procedure. Encouraged by the satisfactory results in the coupling of
aryl bromides and 4-methoxyphenyl boronic acid, we turned our
attention to explore the substrate scope of various arylboronic
acids. As illustrated in Table 3, 4-methylphenyl boronic acid and 4-
tert-butylphenyl boronic acid resulted in similar isolated yields,
96% and 97%, respectively, much higher than a 61% yield obtained
with 4-cyanophenyl boronic acid, which demonstrated that
electron-donating group does promote the coupling process. In
With the optimized reaction conditions in hand, the reaction
scope with various aryl bromides was then explored. As shown in
Table 2, the protocol well tolerates diverse electronic and steric
substituents on one side of the reacting partners, as well as for
heterocyclic substrates. To our delight, aryl bromides all gave out

H. Ren et al. / Tetrahedron 70 (2014) 2829e2837
2833
Table 2
SuzukieMiyaura couplings with various aryl bromidesa
a
1 mmol scale at 100 ꢀC for 24 h. Isolated yield.
addition, with the same catalyst loading as previous aryl bromides,
no reaction is observed. When the catalyst loading was increased
up to 2 mol %, only 30e50% isolated yields were observed.
The relative position of substituents impacted the coupling ef-
ficiency; p-methylphenylboronic acid resulted in a higher yield
than its o-analogue (96% vs 53%). A 22% yield resulted from 2,6-
dimethylphenyl boronic acid suggested that steric substituents on
both sides of the reacting partners could hinder the coupling pro-
cess significantly. Besides, similar moderate yields were obtained
with naphthalenylboronic acid and thiophenylboronic acid (74%,
76% and 87%).
carbenes. The series of NHCs was easily formed with the alkylation
of n-butylbromide, which chelated with palladium to compose new
series of catalyst of SuzukieMiyaura cross-coupling reactions.
Through the evaluation of catalytic activity, the calixarene sup-
ported N-heterocyclic carbenes palladium complexes showed good
performance in SuzukieMiyaura cross-coupling reactions. Un-
fortunately, the conformational study as well as the catalytic results
in catalysis did not allow putting in evidence a supramolecular
effect of the macrocycle cavity towards the coupling process.
Among the screening of substrates, the electron-donating effect
showed accelerating effect on boronic acid, in contrast to the
neglectable influence on bromoarene substrates. The ‘out’ confor-
mation adopted by our new class of N-heterocyclic carbene palla-
dium complexes based on calix[4]arenes, let the metallic centre
and the cavity far from each other. Constraining the active site to
point towards the calixarene core could transfer a supramolecular
effect from the calixarene cavity towards the active catalytic site.
This researched ‘in’ conformation could induce a selectivity to-
wards the all possible products of the reaction. With this goal in
3. Conclusion
In summary, a new series of NHCepalladium catalysts attached
to the calixarene scaffold was developed. After the preparation of
mono-substituted calixarene through conventional procedure,
imidazolyl, 1,2,4-triazolyl and benzimidazolyl groups were directly
attached to calixarene moiety as a precursor of N-heterocyclic

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H. Ren et al. / Tetrahedron 70 (2014) 2829e2837
Table 3
SuzukieMiyaura couplings with various arylboronic acidsa
Me
F3C
F3C
F3C
CN
53% (o)
84% (m)
96% (p)
97%
61%
F3C
R
F3C
CF3
22%
91%
R=CF3 75%
R=F 77%
76% (1-Naphthalenyl-)
74% (2-Naphtealenyl-)
S
F3C
CF3
CF3
S
O
81%
87%
a
1 mmol scale at 100 ꢀC for 24 h. Isolated yield.
mind, new strategies, such as covalent constrain or steric hindrance
are currently tested in our laboratory.
separated and the aqueous phase was extracted with CHCl3
(2ꢂ50 mL). The combined organic layer was washed with NaOH
(2 mol/L, 2ꢂ50 mL), then with water (3ꢂ100 mL) until pH¼5w7.
The organic phase was dried over MgSO4, and evaporated under
reduced pressure. The product was afforded by flash chromatog-
raphy (SiO2, DCM/MeOH, 100:1, v/v) as a light yellow solid. Yield:
0.736 g, 73%. Mp 163.5e166.7 ꢀC. Rf¼0.44 (SiO2, DCM/MeOH, 20:1,
4. Experimental section
4.1. General procedure
All commercial reagents were used as received. Solvents were
dried by conventional methods. All reactions were carried out un-
der nitrogen. Column chromatography was performed using silica
gel (0.040e0.063 nm). Reactions were monitored by TLC on silica
gel plate and visualized by UV light. 1H NMR and 13C NMR spectra
were recorded at 400 and 100 MHz. Mass spectra were acquired on
an LCQ Advantage ion trap instrument, detecting positive ions (þ)
or negative ions (ꢁ) in the ESI mode. Samples (in methanol/
dichloromethane/water, 45:40:15, v/v/v) were infused directly into
the source (5 L/min) using a syringe pump. The bromocalix[4]arene
compound 1 was prepared according to the literature procedure.13a
v/v). 1H NMR (400 MHz, CDCl3):
d 7.32 (br, 1H, NCHC), 7.26 (s, 1H,
NCHN), 7.05e6.99 (m, 4H), 6.87 (t, J¼8.0 Hz, 2H), 6.17 (d, J¼8.0 Hz,
2H), 6.15 (s, 2H), 6.05 (t, J¼8.0 Hz, 1H), 4.50 and 3.17 (AB spin sys-
2
tem, JAB¼16.0 Hz, 4H; ArCH2Ar), 4.44 and 3.16 (AB spin system,
2JAB¼16.0 Hz, 4H; ArCH2Ar), 4.02e3.97 (m, 4H; OCH2), 3.76e3.68
(m, 4H; OCH2), 1.98e1.85 (m, 8H), 18.12e1.06 (m, 6H), 0.91 (t,
J¼8.0 Hz, 6H). 13C NMR (100 MHz, CDCl3):
d 157.58, 155.51, 154.97,
136.87, 135.83, 135.64, 133.61, 129.26 (NCHN), 128.58 (NCH), 127.33
(NCH), 122.15, 121.94, 120.64, 77.08 (OCH2), 76.90 (OCH2), 76.58
(OCH2), 31.06 (ArCH2Ar), 30.92 (ArCH2Ar), 23.44, 23.40, 23.00,
10.70, 10.68, 9.88. HRMS (ESI): calculated for C43H50N2O4 [MþH]þ:
659.3849; found: 659.3820.
4.1.1. 5-(N-Imidazolyl)-25,26,27,28-tetrapropyloxycalix[4]arene
(cone) (2). Into an oven-dried resealable tube were added with 5-
4.1.2. 5-(1-1,2,4-Triazolyl)-25,26,27,28-tetrapropyloxycalix[4]arene
(cone) (3). Into an oven-dried resealable tube were added with 5-
bromo-25,26,27,28-tetrapropyloxycalix[4]arene 1 (0.204 g, 0.30
mmol, 1.0 equiv), 1,2,4-triazole (0.033 g, 0.48 mmol, 1.6 equiv), CuI
(0.030 g, 0.16 mmol, 0.53 equiv), Cs2CO3 (0.205 g, 0.63 mmol,
bromo-25,26,27,28-tetrapropyloxycalix[4]arene
1
(1.027
g,
1.53 mmol, 1.0 equiv), imidazole (0.125 g, 1.84 mmol, 1.2 equiv), CuI
(0.154 g, 0.81 mmol, 0.53 equiv), Cs2CO3 (1.056 g, 3.24 mmol,
2.1 equiv), N,N0-dimethylethylenediamine (42
mL, 0.39 mmol,
0.26 equiv) and 5 mL of dry DMF. The mixture was stirred at 170 ꢀC
for 7 days. After cooling to room temperature, HCl (1 mol/L, 50 mL)
was added followed by CHCl3 (50 mL). The organic layer was
2.1 equiv), N,N0-dimethylethylenediamine (16
mL, 0.15 mmol,
0.50 equiv) and 1.5 mL of dry DMF. The mixture was stirred at
180 ꢀC for 7 days. After cooling to room temperature, HCl (1 mol/L,

H. Ren et al. / Tetrahedron 70 (2014) 2829e2837
2835
20 mL) was added followed by CHCl3 (20 mL). The organic layer was
separated and the aqueous phase was extracted with CHCl3
(2ꢂ20 mL). The combined organic layer was washed with NaOH
(2 mol/L, 2ꢂ20 mL), then with water (3ꢂ50 mL) until pH¼5w7. The
organic phase was dried over MgSO4, and evaporated under re-
duced pressure. The product was afforded by flash chromatography
(SiO2, MeOH/CH2Cl2, 1:100, v/v) as a light yellow solid. Yield:
0.112 g, 57%. Mp 70.9e72.7 ꢀC. Rf¼0.35 (SiO2, DCM/MeOH, 20:1, v/
(OCH2), 76.68 (OCH2), 50.07 (CH2Nþ), 32.30 (ArCH2Ar), 30.97
(ArCH2Ar), 30.91 (ArCH2Ar), 23.40, 23.32, 22.97, 19.47, 10.63, 10.56,
9.89. HRMS (ESI): calculated for C47H59N2O4 [MꢁBr]þ: 715.4469,
found: 715.4448.
4.1.5. 5-(4-Butyl-1-triazolylium)-25,26,27,28-tetrapropyloxycalix[4]
arene bromide (cone) (3a). The stirred mixture of 3 (0.113 g,
0.17 mmol, 1.0 equiv) and bromobutane (1 mL) was heated at reflux
for 24 h. After cooling down to room temperature, the mixture was
evaporated to dryness. The product was afforded through flash
chromatography (SiO2, DCM/MeOH, 20:1, v/v). Yield: 0.054 g, 40%.
Mp 145.2e147.5 ꢀC. Rf¼0.38 (SiO2, DCM/MeOH, 10:1, v/v). 1H NMR
v). 1H NMR (400 MHz, CDCl3):
d 7.96 (br, 2H, triazole), 6.95 (d,
J¼8.0 Hz, 4H), 6.82 (t, J¼8.0 Hz, 2H), 6.50 (s, 2H), 6.25 (d, J¼8.0 Hz,
2H), 5.99 (t, J¼8.0 Hz, 1H), 4.52 and 3.21 (AB spin system,
2JAB¼18.0 Hz, 4H; ArCH2Ar), 4.46 and 3.17 (AB spin system,
2JAB¼16.0 Hz, 4H; ArCH2Ar), 4.03e3.90 (m, 4H, OCH2), 3.82e3.72
(m, 4H, OCH2), 2.00e1.85 (m, 8H), 1.12e1.05 (m, 6H), 0.95 (t,
(400 MHz, CDCl3):
d 11.86 (s, 1H, NCHN), 9.17 (s, 1H, NCHN), 7.14 (s,
2H), 6.73 (d, J¼8.0 Hz, 2H), 6.68e6.60 (m, 4H), 6.45 (d, J¼8.0 Hz,
2H), 6.17 (t, J¼8.0 Hz, 1H), 4.67e4.64 (m, 2H, CH2Nþ), 4.46 and 3.25
(AB spin system, 2JAB¼16.0 Hz, 4H, ArCH2Ar), 4.41 and 3.12 (AB spin
J¼8.0 Hz, 6H). 13C NMR (100 MHz, CDCl3):
d 157.31, 155.77, 136.43,
136.00, 135.43, 133.98, 129.05, 128.49, 127.41, 122.11, 121.55, 119.62,
76.93 (OCH2), 76.77 (OCH2), 76.57 (OCH2), 31.04 (ArCH2Ar), 30.87
(ArCH2Ar), 23.34, 23.29, 23.01, 10.57, 10.55, 9.93. HRMS (ESI): cal-
culated for C42H50N3O4: 660.3796 [MþH]þ, found: 660.3770.
2
system, JAB¼14.0 Hz, 4H, ArCH2Ar), 3.87e3.76 (m, 8H, OCH2),
2.01e1.98 (m, 2H), 1.93e1.84 (m, 8H), 1.01e0.91 (m, 15H). 13C NMR
(100 MHz, CDCl3):
d 158.5, 156.44, 156.36, 143.69 (NCHN), 139.71
(NCHN), 137.52, 135.31, 134.84, 133.84, 128.72, 128.67, 128.28,
127.83, 122.34, 121.30, 119.83, 48.52 (CH2Nþ), 32.14 (ArCH2Ar),
30.90 (ArCH2Ar), 30.83 (ArCH2Ar), 23.15, 23.11, 23.06, 19.32, 13.34,
10.26, 10.20, 10.11. HRMS (ESI): calculated for C46H58N3O4 [MꢁBr]þ:
716.4422, found: 716.4392.
4.1.3. 5-(1-Benzimidazolyl)-25,26,27,28-tetrapropyloxycalix[4]arene
(cone) (4). Into an oven-dried resealable tube were added with 5-
bromo-25,26,27,28-tetrapropyloxycalix[4]arene
1
(0.208 g,
0.31 mmol, 1.0 equiv), benzimidazole (0.056 g, 0.46 mmol,
1.5 equiv), CuI (0.034 g, 0.18 mmol, 0.58 equiv), Cs2CO3 (0.215 g,
0.66 mmol, 2.1 equiv), N,N0-dimethylethylenediamine (17
mL,
4.1.6. 5-(3-Butyl-1-benzimidazolylium)-25,26,27,28-tetrapropyloxy
calix[4]arene bromide (cone) (4a). The stirred mixture of 4 (0.250 g,
0.35 mmol,1.0 equiv) and bromobutane (2 mL) was heated at reflux
for 24 h. After cooling down to room temperature, the mixture was
evaporated to dryness. The product was afforded through flash
chromatography (SiO2, DCM/MeOH, 20:1, v/v). Yield: 0.239 g, 81%.
Mp 145.2e147.5 ꢀC. Rf¼0.50 (SiO2, DCM/MeOH, 10:1, v/v). 1H NMR
0.16 mmol, 0.5 equiv) and 1.5 mL of dry DMF. The mixture was
stirred at 180 ꢀC for 7 days. After cooling to room temperature, HCl
(1 mol/L, 20 mL) was added followed by CHCl3 (20 mL). The organic
layer was separated and the aqueous phase was extracted with
CHCl3 (2ꢂ20 mL). The combined organic layer was washed with
NaOH (2 mol/L, 2ꢂ20 mL), then with water (3ꢂ50 mL) until
pH¼5w7. The organic phase was dried over MgSO4, and evaporated
under reduced pressure. The product was afforded by flash chro-
matography (SiO2, DCM/MeOH, 100:1, v/v) as a light yellow solid.
Yield: 0.123 g, 56%. Mp 83.7e86.1 ꢀC. Rf¼0.41 (SiO2, DCM/MeOH,
(300 MHz, CDCl3):
d 11.16 (s, 1H, NCHN), 7.63e7.55 (m, 2H),
7.45e7.39 (m, 1H), 7.20e7.12 (m, 4H), 6.95e6.90 (m, 2H), 6.62 (s,
2H), 6.36 (d, J¼9.0 Hz,1H), 6.23 (d, J¼9.0 Hz, 2H), 5.69e5.63 (m,1H),
4.86e4.81 (m, 2H, CH2Nþ), 4.53 and 3.31 (AB spin system,
2JAB¼12.5 Hz, 4H, ArCH2Ar), 4.48 and 3.18 (AB spin system,
2JAB¼12.0 Hz, 4H, ArCH2Ar), 4.16e3.98 (m, 4H, OCH2), 3.80e3.75
(m, 2H, OCH2), 3.70e3.65 (m, 2H, OCH2), 2.08e1.86 (m, 10H),
1.49e1.42 (m, 2H), 1.15e1.06 (m, 6H), 0.98e0.90 (m, 9H). 13C NMR
20:1, v/v). 1H NMR (400 MHz, CDCl3):
d 7.69 (br, 1H, benzimidazole),
7.18e7.15 (m, 2H), 7.10 (t, J¼8.0 Hz, 1H, benzimidazole), 7.03 (d,
J¼8.0 Hz, 2H), 6.96 (d, J¼8.0 Hz, 2H), 6.82 (t, J¼8.0 Hz, 2H), 6.29 (s,
2H), 6.14 (d, J¼8.0 Hz, 2H), 5.81e5.78 (m,1H), 4.48 and 3.14 (AB spin
system, 2JAB¼14.0 Hz, 4H, ArCH2Ar), 4.40 and 3.11 (AB spin system,
2JAB¼12.0 Hz, 4H, ArCH2Ar), 4.05e3.91 (m, 4H, OCH2) 3.72e3.60 (m,
4H, OCH2), 1.97e1.79 (m, 8H), 1.08e1.00 (m, 6H), 0.86 (t, J¼8.0 Hz,
(75 MHz, CDCl3):
d 157.39, 156.96, 155.31, 141.24 (NCHN), 136.87,
136.57, 136.07, 133.45, 131.16, 130.64, 129.18, 129.08, 127.47, 127.04,
126.45, 126.33, 123.39, 122.54, 121.84, 114.92, 112.47, 77.68, 77.33
(OCH2), 76.64 (OCH2), 47.38 (CH2Nþ), 31.63 (ArCH2Ar), 30.91
(ArCH2Ar), 30.87 (ArCH2Ar), 23.46, 23.39, 22.94, 19.78, 13.56, 10.71,
10.63, 9.79. HRMS (ESI): calculated for C51H61N2O4 [MꢁBr]þ:
765.4626, found: 765.4591.
6H). 13C NMR (100 MHz, CDCl3):
d 157.5, 155.25, 154.96, 136.98,
136.00,135.56,133.25,129.25,128.62,127.57,122.66, 122.32,122.22,
119.88 (NCHN), 77.08 (OCH2), 76.59 (OCH2), 31.04 (ArCH2Ar), 30.89
(ArCH2Ar), 23.46, 22.97, 10.72, 9.84. HRMS (ESI): calculated for
C
47H53N2O4 [MþH]þ: 709.4000, found: 709.3997.
4.2. Palladium complexes
4.1.4. 5-(3-Butyl-1-imidazolylium)-25,26,27,28-tetrapropyloxycalix
[4] arene bromide (cone) (2a). The stirred mixture of 2 (0.157 g,
0.24 mmol, 1.0 equiv) and bromobutane (2 mL) was heated at reflux
for 24 h. The precipitate formed was collected by filtration and
washed with petroleum ether. The white solid was dried under
vacuum and used without further purification. Yield: 0.136 g, 72%.
Mp 152.7e155.4 ꢀC. Rf¼0.42 (SiO2, DCM/MeOH, 10:1, v/v). 1H NMR
4.2.1. [5-(3-Butylimidazol-2-yliden-1-yl)-25,26,27,28-tetrapropyloxy
calix[4]arene] (pyridine) palladium(II) dibromide (cone) (2b). A
mixture of bromide 2a (0.050 g, 0.063 mmol, 1.0 equiv), PdCl2
(0.013 g, 0.073 mmol, 1.2 equiv), K2CO3 (0.067 g, 0.49 mmol,
7.8 equiv), KBr (0.152 g, 1.27 mmol, 20.0 equiv) in pyridine (5 mL)
was stirred at 80 ꢀC for 22 h under a nitrogen atmosphere. After
cooling to room temperature, the mixture was evaporated to dry-
ness. The crude mixture was purified by flash chromatography
(SiO2, DCM/MeOH, 50:1, v/v) to afford aspect product. Yield:
0.065 g, 97%. Mp 120.1e123.0 ꢀC. Rf¼0.55 (SiO2, DCM/MeOH, 100:1,
(400 MHz, CDCl3): d 10.47 (br, 1H, NCHN), 7.31 (s, 1H, NCH), 7.05 (d,
J¼8.0 Hz, 2H), 6.99 (d, J¼8.0 Hz, 2H), 6.86 (t, J¼8.0 Hz, 2H), 6.73 (s,
1H, NCH), 6.41 (s, 2H), 6.24 (d, J¼8.0 Hz, 2H), 6.06 (t, J¼8.0 Hz, 1H),
4.58e4.55 (m, 2H, CH2Nþ), 4.49 and 3.25 (AB spin system,
2JAB¼14.0 Hz, 4H, ArCH2Ar), 4.44 and 3.16 (AB spin system,
2JAB¼14.0 Hz, 4H, ArCH2Ar), 4.04e3.90 (m, 4H, OCH2), 3.79e3.69
(m, 4H, OCH2), 1.97e1.86 (m, 10H), 1.43e1.37 (m, 2H), 1.10e1.04 (m,
v/v). 1H NMR (400 MHz, CDCl3):
d 8.82e8.80 (m, 2H, o-N in pyri-
dine), 7.60e7.57 (m, 1H, p-N in pyridine), 7.18 (s, 1H, NCH in imid-
azole), 7.15e7.12 (m, 2H, m-N in pyridine), 6.90 (d, 1H, NCH in
imidazole), 6.74e6.68 (m, 5H), 6.55e6.52 (m, 1H), 6.39e6.37 (m,
2H), 6.27e6.24 (m, 2H), 4.51 (t, J¼8.0 Hz, 2H, CH2Nþ), 4.50 and 3.28
(AB spin system, 2JAB¼14.0 Hz, 4H, ArCH2Ar), 4.47 and 3.16 (AB spin
6H), 0.97e0.90 (m, 9H). 13C NMR (100 MHz, CDCl3):
d 157.36,157.28,
155.97, 137.01, 136.45, 135.88, 135.40, 134.21, 129.20, 128.93, 128.37,
127.26, 122.46, 121.49, 121.33, 121.09, 120.52, 77.32 (OCH2), 77.20

2836
H. Ren et al. / Tetrahedron 70 (2014) 2829e2837
2
system, JAB¼16.0 Hz, 4H, ArCH2Ar), 3.93e3.80 (m, 4H, OCH2),
3.76e3.72 (m, 4H, OCH2), 2.06e2.03 (m, 2H), 1.95e1.83 (m, 8H),
1.49e1.43 (m, 6H), 1.00e0.88 (m, 15H). 13C NMR (100 MHz, CDCl3):
(0.015 g, 0.086 mmol, 1.2 equiv), K2CO3 (0.118 g, 0.86 mmol,
12.6 equiv), KBr (0.184 g, 1.54 mmol, 23.0 equiv) in pyridine (1 mL)
was stirred at 80 ꢀC for 22 h under a nitrogen atmosphere. After
cooling to room temperature, the mixture was evaporated to dry-
ness. The crude mixture was purified by flash chromatography
(SiO2, DCM) to afford aspect product as a yellow solid. Yield:
0.040 g, 56%. Mp 115.3e116.9 ꢀC. Rf¼0.50 (SiO2, DCM). 1H NMR
d
157.09, 156.97, 155.93, 152.55 (o-N in pyridine), 147.41 (NCN),
137.48, 136.25, 135.72, 134.29, 133.91, 133.24, 128.72 (p-N in pyri-
dine), 128.19, 127.94, 126.47, 124.28 (m-N in pyridine), 123.40,
122.24, 121.64, 121.23, 77.20 (OCH2), 76.87 (OCH2), 76.65 (OCH2),
51.13 (CH2Nþ), 32.01 (ArCH2Ar), 30.91 (ArCH2Ar), 29.65 (ArCH2Ar),
23.27, 23.23, 23.14, 20.02, 13.79, 10.41, 10.20, 10.16. MS (ESI): cal-
culated for C52H63N3O4Pd2þ [Mꢁ2Br]2þ: 899.4, found: 899.3.
Found: C, 59.62; H, 6.03; N, 4.01%. Calculated for C52H67Br2N3O6Pd
[Mþ2H2O] (Mr¼1096.33): C, 56.97; H, 6.16; N, 3.83%.
(400 MHz, CDCl3): d 8.88e8.86 (m, 2H, o-N in pyridine), 8.03 (s, 1H),
7.80 (s, 2H), 7.65e7.61 (m, 1H, p-N in pyridine), 7.20e7.16 (m, 2H, m-
N in pyridine), 6.91e6.88 (m, 2H), 6.73e6.70 (m, 1H), 6.50e6.48 (m,
2H), 6.12e6.06 (m, 4H), 4.59 (t, J¼8.0 Hz, 2H, CH2Nþ), 4.45 and 3.22
(AB spin system, 2JAB¼12.0 Hz, 4H, ArCH2Ar), 4.38 and 3.07 (AB spin
2
system, JAB¼14.0 Hz, 4H, ArCH2Ar), 4.02e3.89 (m, 4H, OCH2),
4.2.2. [5-(3-Butylimidazol-2-yliden-1-yl)-25,26,27,28-tetrapropyl
oxycalix[4]arene] (N-quinoline) palladium(II) dibromide (cone)
(2c). A mixture of bromide 2a (0.051 g, 0.064 mmol, 1.0 equiv),
PdCl2 (0.014 g, 0.077 mmol, 1.2 equiv), K2CO3 (0.044 g, 0.32 mmol,
5.0 equiv), KBr (0.155 g, 1.28 mmol, 20.0 equiv) and quinoline
3.65e3.62 (m, 4H, OCH2), 2.21e2.13 (m, 2H), 1.95e1.86 (m, 4H),
1.84e1.77 (m, 4H), 1.51e1.46 (m, 2H), 1.03e0.98 (m, 9H), 0.90e0.83
(m, 6H). 13C NMR (100 MHz, CDCl3):
d 158.42, 157.61, 155.53, 155.34,
152.69, 142.40, 137.83, 137.12, 136.61, 133.50, 132.84, 132.79, 128.70,
128.27, 127.58, 125.86, 124.52, 122.22, 121.77, 76.86 (OCH2), 76.75
(OCH2), 76.42 (OCH2), 49.33 (CH2Nþ), 31.64 (ArCH2Ar), 30.95
(ArCH2Ar), 23.42, 23.12, 23.01, 19.90, 13.66, 10.68, 9.98, 9.92. MS
(ESI): calculated for C51H64N4O4Pd [Mꢁ2Br]þ: 902.4, found: 902.3.
Found: C, 57.57; H, 5.97; N, 5.13%. Calculated for C51H62Br2N4O4Pd
(Mr¼1058.22): C, 57.72; H, 5.89; N, 5.28%.
(380 mL, 3.2 mmol, 50.0 equiv) in dioxane (1 mL) was stirred at
80 ꢀC for 24 h under a nitrogen atmosphere. After cooling to room
temperature, the mixture was evaporated to dryness. The crude
mixture was purified by flash chromatography (SiO2, DCM) to af-
ford aspect product. Yield: 0.029 g, 41%. Mp 160.0e162.5 ꢀC.
Rf¼0.64 (SiO2, DCM). 1H NMR (400 MHz, CDCl3):
8.15 (d, J¼8.0 Hz,
d
1H, o-N in quinoline), 7.75 (d, J¼8.0 Hz, 1H), 7.57e7.42 (m, 3H),
7.30e7.28 (m, 1H), 7.18e7.12 (m, 2H), 6.87e6.77 (m, 3H), 6.68e6.36
(m, 5H), 4.66 (t, J¼8.0 Hz, 2H, CH2Nþ), 4.61 and 3.37 (AB spin sys-
4.2.5. [5-(3-Butylbenzimidazol-2-yliden-1-yl)-25,26,27,28-tetrapro-
pyloxy calix[4]arene] (pyridine) palladium(II) dibromide (cone)
(4b). A mixture of bromide 4a (0.233 g, 0.28 mmol,1.0 equiv), PdCl2
(0.059 g, 0.33 mmol, 1.2 equiv), K2CO3 (0.318 g, 2.30 mmol,
8.3 equiv), KBr (0.662 g, 5.56 mmol, 20 equiv) in pyridine (5 mL)
was stirred at 80 ꢀC for 22 h under a nitrogen atmosphere. After
cooling to room temperature, the mixture was evaporated to dry-
ness. The crude mixture was purified by flash chromatography
(SiO2, DCM) to afford product as a yellow solid. Yield: 0.248 g, 81%.
Mp 141.8e142.8 ꢀC. Rf¼0.48 (SiO2, DCM). 1H NMR (400 MHz, tolu-
2
tem, JAB¼12.0 Hz, 4H, ArCH2Ar), 4.51 and 3.19 (AB spin system,
2JAB¼14.0 Hz, 4H, ArCH2Ar), 4.06e3.77 (m, 8H, OCH2), 2.27e2.20
(m, 2H), 2.09e1.89 (m, 8H), 1.63e1.57 (m, 2H), 1.14e0.98 (m, 15H).
13C NMR (100 MHz, CDCl3):
d 152.97, 146.55 (NCN), 137.91, 135.52,
133.57, 130.26, 129.24, 129.11, 128.59, 127.87, 127.72, 127.27, 126.31,
123.39, 122.56, 121.80, 121.20, 121.08, 76.83 (OCH2), 51.24 (CH2Nþ),
32.07 (ArCH2Ar), 31.07 (ArCH2Ar), 30.93 (ArCH2Ar), 23.42, 23.31,
23.17, 20.16, 13.82, 10.18. HRMS (ESI): calculated for C47H59N2O4þ
[Mꢁ2BrePdþH]þ: 715.4469, found: 715.4434.
ene-d8):
d 8.87 (br, 2H, o-N in pyridine), 7.48 (s, 2H), 6.89e6.72 (m,
6H), 6.60 (d, J¼8.0 Hz, 2H), 6.54 (d, J¼8.0 Hz, 1H), 6.39e6.37 (m,
3H), 6.28e6.26 (m, 2H), 6.13 (t, 2H, J¼8.0 Hz), 4.64e4.61 (m, 2H,
CH2Nþ), 4.38 and 3.09 (AB spin system, 2JAB¼12.0 Hz, 4H, ArCH2Ar),
4.2.3. [5-(3-Butylimidazol-2-yliden-1-yl)-25,26,27,28-
tetrapropyloxy calix[4]arene] (N-isoquinoline) palladium (II)di-
bromide (cone) (2d). A mixture of bromide 2a (0.050 g, 0.063 mmol,
1.0 equiv), PdCl2 (0.014 g, 0.076 mmol, 1.2 equiv), K2CO3 (0.044 g,
0.32 mmol, 5.0 equiv), KBr (0.153 g, 1.26 mmol, 20.0 equiv) and
2
4.32 and 2.92 (AB spin system, JAB¼14.0 Hz, 4H, ArCH2Ar),
3.85e3.82 (m, 2H, OCH2), 3.73 (t, J¼8.0 Hz, 2H, OCH2), 3.58 (t,
J¼8.0 Hz, 4H, OCH2), 2.13e2.09 (m, 2H), 1.81e1.65 (m, 8H),
1.32e1.26 (m, 2H), 0.81e0.70 (m, 15H). 13C NMR (100 MHz, toluene-
isoquinoline (380
mL, 3.2 mmol, 50.0 equiv) in dioxane (1 mL) was
d8): d 165.97, 158.22, 157.78, 156.65, 153.46 (o-N in pyridine), 137.80,
stirred at 80 ꢀC for 24 h under a nitrogen atmosphere. After cooling
to room temperature, the mixture was evaporated to dryness. The
crude mixture was purified by flash chromatography (SiO2, DCM) to
afford aspect product. Yield: 0.052 g, 74%. Mp 104.9e106.6 ꢀC.
129.99, 129.59, 129.32, 129.28, 129.08, 128.82, 128.45, 128.21, 127.97,
125.36, 124.17, 123.40, 123.32, 112.23, 110.60, 77.50 (OCH2), 77.37
(OCH2), 77.24 (OCH2), 49.42 (CH2Nþ), 31.92 (ArCH2Ar), 31.63
(ArCH2Ar), 23.99, 23.97, 23.84, 14.07, 10.91, 10.70,10.67. HRMS (ESI):
Rf¼0.72 (SiO2, DCM). 1H NMR (400 MHz, CDCl3):
d
9.33 (s, 1H, o-N in
calculated for
949.2720.
C
56H65N3O4Pd [Mꢁ2Br]2þ
:
949.4010, found:
isoquinoline), 8.71 (d, 1H, J¼8.0 Hz, o-N in isoquinoline), 7.76e7.55
(m, 3H), 7.57e7.56 (m, 2H), 7.39 (s, 1H), 7.26 (s, 1H), 7.00 (s, 1H),
6.93e6.81 (m, 5H), 6.70e6.67 (m,1H), 6.44 (d, J¼4.0 Hz, 2H), 6.26 (t,
J¼8.0 Hz, 2H), 4.64 (t, J¼8.0 Hz, 2H, CH2Nþ), 4.54 and 3.31 (AB spin
system, 2JAB¼14.0 Hz, 4H, ArCH2Ar), 4.48 and 3.17 (AB spin system,
2JAB¼12.0 Hz, 4H, ArCH2Ar), 4.05e3.79 (m, 8H, OCH2), 2.16e2.14 (m,
4.2.6. General procedure for Pd-catalysed SuzukieMiyaura cou-
pling. In air, potassium phosphate (3 mmol, 0.636 g), catalyst 1
(0.08 mol %, 0.0009 g) and arylboronic acid (2 mmol) were weighed
into a 50 mL glass vial that was sealed with a septum and purged
with N2 (3ꢂ). Dioxane (1 mL) was then injected via syringe fol-
lowed by the aryl bromide (1 mmol) (if liquid). If the aryl bromide
was a solid, it was introduced into the vial prior to purging with N2.
At this time, the reaction stirred for 24 h at 100 ꢀC. The reaction
mixture was concentrated in vacuo and directly purified via silica
gel flash chromatography.
2H), 2.07e1.91 (m, 8H), 1.60e1.54 (m, 2H), 1.10e0.97 (m, 15H). 13
C
NMR (100 MHz, CDCl3):
d 157.19, 157.00, 155.99, 155.83, 148.36
(NCN), 144.14, 136.35, 135.86, 134.12, 133.80, 131.92, 128.88, 128.45,
128.30, 128.27, 127.97, 127.83, 126.86, 126.16, 123.47, 122.49, 121.72,
121.34, 121.16, 76.88 (OCH2), 76.62 (OCH2), 51.15 (CH2Nþ), 32.04
(ArCH2Ar), 30.92 (ArCH2Ar), 29.66 (ArCH2Ar), 23.79, 23.30, 23.24,
23.12, 20.07, 13.82, 10.45, 10.19, 10.14. HRMS (ESI): calculated for
C
47H59N2O4 [Mꢁ2BrePdþH]þ: 715.4475, found: 715.4436.
Acknowledgements
4.2.4. [5-(4-Butyltriazol-2-yliden-1-yl)-25,26,27,28-tetrapropyloxy
calix[4]arene] (pyridine) palladium(II) dibromide (cone) (3b). A
mixture of bromide 3a (0.054 g, 0.068 mmol, 1.0 equiv), PdCl2
Financial support from the National Natural Science Foundation
of China (Nos. 21172045 and 20902001), the Changjiang Scholars
ꢀ
and Innovative Research Team in University (IRT1117), Universite

H. Ren et al. / Tetrahedron 70 (2014) 2829e2837
2837
Organomet. Chem. 2009, 694, 389e396; (h) Zhou, Y.; Xi, Z.; Chen, W.; Wang, D.
Organometallics 2008, 27, 5911e5920; (i) Xi, Z.; Zhang, X.; Chen, W.; Fu, S.;
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C.; Hu, C.; Lee, H. Chem.dEur. J. 2007, 13, 582e591.
Claude Bernard Lyon1, and Department of Chemistry of Fudan
University is gratefully acknowledged.
6. (a) Mandolini, L.; Ungaro, R. In Calixarenes in Action; Imperial College Press:
London, UK, 2000; (b) Gutsche, C. D. In Calixarenes Revisited; Stoddart, J. F., Ed.;
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Supplementary data
NMR spectra and mass analyses of all new compounds and
complexes (Figs. S1eS54); X-ray data for compounds 2b and 4b
(Tables 1 and 2 and Figs. S55 and S56) and in CIF format. This
material is available free of charge via the Internet at http://pub-
s.acs.org. Supplementary data associated with this article can be
found in the online version, at http://dx.doi.org/10.1016/
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€
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