Base-free Pd-MOF catalyzed the Suzuki-Miyaura cross-coupling reaction of arenediazonium tetrafluoroborate salts with arylboronic acids

Article abstract of DOI:10.1016/j.tet.2019.130540

A convenient and environmental benign synthesis of biaryls has been demonstrated by a straightforward reaction catalyzed by the palladium-containing metal-organic framework (Pd-MOF) [Pd (2-pymo)₂]_n (2-pymo = 2-pyrimidinolate). A series of functionalized biaryl derivatives have been synthesized in good to excellent yields by the Suzuki-miyaura cross-couplings of sustainable arenediazonium salts with a variety of arylboronic acids and the reactions were catalyzed by the Pd-MOF using methanol as a benign solvent. Those base- and additive-free catalytic reactions proceeded smoothly under non-anhydrous and non-degassed condition. Such transformation avoided high reaction temperature, tolerated many functional groups and presented a wide substrate scope. The catalyst could be recovered by filtration and reused for four successive cycles before collapse of the MOF structure.

Full text of DOI:10.1016/j.tet.2019.130540

Journal Pre-proof
Base-free Pd-MOF catalyzed the Suzuki-Miyaura cross-coupling reaction of
arenediazonium tetrafluoroborate salts with arylboronic acids
Yangyang Liu, Jie Wang, Tang Li, Zesheng Zhao, Wan Pang
PII:
S0040-4020(19)30873-7
https://doi.org/10.1016/j.tet.2019.130540
TET 130540
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 13 June 2019
Revised Date: 16 August 2019
Accepted Date: 20 August 2019
Please cite this article as: Liu Y, Wang J, Li T, Zhao Z, Pang W, Base-free Pd-MOF catalyzed the
Suzuki-Miyaura cross-coupling reaction of arenediazonium tetrafluoroborate salts with arylboronic acids,
Tetrahedron (2019), doi: https://doi.org/10.1016/j.tet.2019.130540.
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Graphical Abstract
A convenient and environmental benign synthesis of biaryls has been demonstrated by a straightforward reaction catalyzed
by the palladium-containing metal-organic framework (Pd-MOF) [Pd(2-pymo)2]n (2-pymo=2-pyrimidinolate).
Base-free Pd-MOF catalyzed the Suzuki-
Miyaura cross-coupling reaction of
arenediazonium tetrafluoroborate salts with
arylboronic acids
Leave this area blank for abstract info.
Yangyang Liu, Jie Wang, Tang Li, Zesheng Zhao and Wan Pang*
School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Haiquan Road,
Shanghai 201418, China
Fonts or abstract dimensions should not be changed or altered.

Tetrahedron
journal homepage: www.elsevier.com
Base-free Pd-MOF catalyzed the Suzuki-Miyaura cross-coupling reaction of
arenediazonium tetrafluoroborate salts with arylboronic acids
Yangyang Liu, Jie Wang, Tang Li, Zesheng Zhao and Wan Pang*
School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Haiquan Road, Shanghai 201418, China
ARTICLE INFO
ABSTRACT
Article history:
Received
A convenient and environmental benign synthesis of biaryls has been demonstrated by a
straightforward reaction catalyzed by the palladium-containing metal-organic framework (Pd-
Received in revised form
Accepted
Available online
MOF) [Pd (2-pymo)2] (2-pymo=2-pyrimidinolate). A series of functionalized biaryl derivatives
n
have been synthesized in good to excellent yields by the Suzuki-miyaura cross-couplings of
sustainable arenediazonium salts with a variety of arylboronic acids and the reactions were
catalyzed by the Pd-MOF using methanol as a benign solvent. Those base- and additive-free
catalytic reactions proceeded smoothly under non-anhydrous and non-degassed condition. Such
transformation avoided high reaction temperature, tolerated many functional groups and
presented a wide substrate scope. The catalyst could be recovered by filtration and reused for
four successive cycles before collapse of the MOF structure.
Keywords:
Pd-MOF
Suzuki-Miyaura
2009 Elsevier Ltd. All rights reserved
.
Arenediazonium tetrafluoroborate salts
Suzuki-Miyaura
reaction,
employing
arenediazonium
tetrafluoroborate salts as a coupling component provides a base-
free, energy and cost-saving protocol. Although palladium-
1. Introduction
catalyzed
cross-coupling
reaction
of
arenediazonium
The palladium catalyzed Suzuki-Miyaura cross-coupling
reaction is one of the most reliable and powerful methods to form
C-C bonds for the synthesis of biaryls [1], which constitute a
class of key structural motifs present in numerous biological
important compounds [2], and advanced functional materials [3].
The vast majority of traditional Suzuki-Miyaura reactions have
used costly halogenated or sulfonated electrophilic component
[4]. Moreover, such methodologies that are based on aromatic
halides require a base and an elevated temperature, which limited
the scope of these protocols. Thus, in order to expand the scope
of the Suzuki-type coupling reaction, more and more attentions
have been paid to the generation of suitable electrophilic
coupling partners in recent years. Among the electrophilic
coupling components, aromatic diazonium salts (ADS) are found
to be good choices due to their high reactivity and easy
preparation [5]. In addition, ADS can be considered as super
electrophiles since they are armed with diazonium function (N2)
as nucleophile, which allows the cross-coupling reactions to
proceed efficiently under a simple and mild experimental
procedure. Comparison to the typical
tetrafluoroborate salts (ArN2 BF4-) and arylboronic acids had
been successful by employing diverse homogeneous [6] or
heterogeneous catalyst [7], there is a resurgent interest in the
development of more efficient methods for this transformation.
Among the growing list of organometallic complexes, metal-
organic frameworks (MOFs) have been investigated extensively
because of their high surface areas, well-defined porosities, and
chemical tenability [8]. In recent years, MOFs have been
extensively demonstrated in their potential and promising
applications as heterogeneous catalysts [9], especially those using
MOFs as a supporting matrix for metal nanoparticles (known as
metal@MOFs) [10]. However, few studies have been conducted
on Pd-MOF that can be used as a new heterogeneous catalyst.
Xamena et al. reported [Pd(2-pymo)2]n (2-pymo=2-
pyrimidinolate) as active catalyst for alcohol oxidation, Suzuki
C-C coupling, and olefin hydrogenation[11]. Klemm et al.
reported on the stability and reusability of this Pd-MOF in liquid-
phase hydrogenation reaction [12], and the role of Pd2+/Pd0 in
hydrogenation by X-ray absorption and IR spectroscopic study
[13].
+
For our investigations, the well studied Pd-MOF [Pd(2-
pymo)2]n reported by Navarro et al. [14] was chosen to be the
catalyst, which is an outstanding example of MOF material
design for catalytic application. It was reported that the Pd2+
* Corresponding author.
E-mail address: pangwan@sit.edu.cn (W. Pang).

Tetrahedron
2
Entry
Additive
nothing
Solvent
MeOH
Yield% b
nodes of the MOF [Pd(2-pymo)2]n could be active centers in
hydrogenation of 1-octene [14]. Although its catalytic
performance has been tested by Xamena et al. [11] in Suzuki-
Miyaura coupling between aryl halides and arylboronic acids.
The methodology was base on costly aromatic halides in toxic
organic solvent (o-xylene), required a base (K2CO3) and an
elevated temperature (150 ). In addition, no detailed scopes and
limitations studies have been reported so far.
In the present work, Pd-MOF complex was employed to
catalyze the coupling of functionalized aromatic diazonium
tetrafluoroborate salts with diverse arylboronic acids under
additive- and base-free condition, methanol as the solvent and a
mind temperature about 40 .
1
N.R
N.R
2
3
K2PdCl4
MeOH
MeOH
N.R
Pd(C4H4N2O)2Cl2
4
5
MeOH
MeOH
MeOH
46
99
intermediate 1
2. Result and discussion
catalyst 1
catalyst 1
The Pd-MOF [Pd(2-pymo)2]n.2nH2O catalyst 1 was prepared
and purified according to Jorge A. R. Navarro’s reported
procedure (Scheme 1) [14], and its structure was confirmed by X-
6c
N.R
ray diffraction using
diffractometer and compared with literatures (see ESI†).
a PANalytical X’Pert Pro powder
a Reaction conditions: 2-(carboxyethyl)benzenediazonium tetrafluoroborate
salt (0.2 mmol), phenylboronic acid (0.3 mmol) and 3 mol% additive in
solvent (1.0 ml) at 40ꢀ(oil temperature) for 4 hours.
b The yield was determined by 1H NMR spectroscopy using 1,3,5-
Trimethoxybenzene as an internal standard.
c Reaction was performed without 2-(carboxyethyl) benzenediazonium
tetrafluoroborate salt
Subsequently, the effect of catalyst loading on the cross-
coupling reaction was investigated under air atmosphere at 40℃
and the results are shown in Table 2. The yields were improved
apparently with the increase of the catalyst, 99% of yield was
obtained when as low as 3 mol% Pd-MOF was utilized (Table 2,
entry 3). The investigation of some solvents usually used in
Suzuki-Miyaura cross-coupling, such as MeOH, EtOH H2O,
revealed that MeOH was the best solvent (Table 2, entry 3). In
sharp contrast, the yield of the model reaction was dramatically
decreased when EtOH was used as solvent (Table 2, entry 6). On
the other hand, when water was employed as the reaction solvent,
the yield was relatively lower than MeOH (Table 2, entry 5).
Comparatively, the yield of the model reaction was improved
when a mixture of MeOH: H2O was used (Table 2, entries 8-11).
Temperature obviously influenced the reaction yields too. 40ꢀ
was found to be suitable temperature (Table 2, entry 3). Reducing
the reaction temperature form 40ꢀ to 25ꢀ, the product yield
was dramatically decreased (Table 2, entry 12). A brief survey of
the bases revealed that the addition of base has significantly
reduced the product formation (Table 2, entries 14-21). The loss
of catalytic activity presumably resulted from the instability of
Pd-MOF under alkaline conditions. After all these extensive
experiments, it was discovered that the optimal conditions
employed 3mol% Pd-MOF and no base in MeOH at 40℃, which
provide biphenyl in 98% isolated yield.
Scheme 1 Preparation of catalyst 1
As a starting point in the investigation of the best operating
experimental conditions, the Suzuki-Miyaura cross-coupling
reaction
between
2-(carboxyethyl)benzenediazonium
tetrafluoroborate and phenylboronic acid was selected as the
representative substrate.
Firstly, the catalytic activity of the catalyst 1 was tested, and
the results are summarized in Table 1. Without catalyst, the
treatment of 2-(carboxyethyl)benzendiazonium tetrafluoroborate
(1d) and phenylboronic acid (2) using MeOH as solvent resulted
in no reaction (Table 1, entry 1). Similarly, no biphenyl product
was detected when K2PdCl4 or 2-pyrimidinol hydrochloride was
used as the catalyst under same reaction condition (Table 1,
entries 2 and 3). Excellent yields were observed for the coupling
reaction when using the catalyst 1 without base for 4 hours
(Table 1, entry 5), where in the presence of intermediate 1, 46%
yield was obtained (Table 1, entry 4). The synthetic catalyst 1
(Pd-MOF) proved to be exceptionally active for Suzuki-Miyaura
reaction in base-free condition. Note that biphenyl that may come
from homocoupling of phenylboronic acid has been eliminated as
supported by the fact that no biphenyl product is observed under
the same experimental conditions except for the absence of 2-
(carboxyethyl)benzenediazonium tetrfluoroborate (Table 1, entry
6).
To ascertain the scope and limitations of this reaction, a
variety of arenediazonium tetrafluoroborate salts were
investigated (Table 3). As described in Table 3, the nature of the
substituents on the diazonium salt does not seem to affect greatly
the reaction yields. Arenediazonium fluoroborate bearing either
electron withdrawing functional groups or donating groups react
smoothly giving moderate to excellent yields (46-98%).
Additionally, compared with the corresponding meta- and para-
substituted arenendiazonium tetrafluoroborate salts, the yields of
the orhto-substituted derivatives gave higher yields in shorter
reaction times (Table 3, entries 4, 6 and 9), probably because of
the ortho-effect. Halogen atoms such as F, Cl, Br and I were also
tolerated under the reaction conditions in moderate yields (Table
3, entries 11-14).
Table1
Palladium-Catalyzed Suzuki-Miyaura cross-coupling reactiona

Tetrahedron
3
Table 2
Optimization of the cross-coupling reaction with Pd-MOF catalysta
Entry
1
Pd-MOF(mol%)
Solvent
MeOH
Bases
—
T c/
40
40
40
40
40
40
40
40
40
40
40
25
30
40
40
40
40
40
40
40
40
Yield b(%)
70
2
2.5
3
2
MeOH
—
85
3
MeOH
—
99
4
5
MeOH
—
98
5
3
H2O
—
64
6
3
EtOH
—
42
7
3
EtOH /H2O(1/1)
MeOH /H2O(1/1)
MeOH /H2O(2/1)
MeOH /H2O(5/1)
MeOH /H2O(9/1)
MeOH
—
52
8
3
—
70
9
3
—
76
10
11
12
13
14
15
16
17
18
19
20
21
3
—
80
3
—
80
3
—
15
3
MeOH
—
46
3
MeOH
K2CO3
K3PO4
NaOH
NaHCO3
AcONa
NH3·H2O
Et3N
Py
Trace
Trace
Trace
Trace
Trace
Trace
Trace
Trace
3
MeOH
3
MeOH
3
MeOH
3
MeOH
3
MeOH
3
MeOH
3
MeOH
a Reaction conditions: to the reaction mixture of 2-(carboxyethyl)benzendiazonium tetrafluoroborate salt 1d (0.2 mmol) and Phenylboronic acid 2 (0.3 mmol) in solvent
(1.0 ml).
b The yield was determined by 1H NMR spectroscopy using 1,3,5-Trimethoxybenzene as an internal standard.
c Oil temperature
Table3
Pd-MOF catalyzed Suzuki-Miyaura cross-coupling reaction of arenediazonium tetrafluoroborate salts derivatives with
arylboronic acids a

Tetrahedron
4
a Reaction conditions: arenediazonium tetrafluoroborate salts 1a-n (1.0 mmol) and Phenylboronic acid 2 (1.5 mmol) in methanol solution (5.0 ml), Pd-MOF (3
mol%), 40 oil temperature
In the meantime, arylboronic acids having different
substituents were examined and the results are listed in Table 4.
As shown in Table 4, a series of substituted arylboronic acids
bearing either electron-donating (entries 1-4) or electron-
withdrawing (entries 5-6) functional groups afforded the desired
products (4a-e) in fair to excellent yields. However, boronic acid
substrates bearing electron donating groups, such as p-OMe, p-
Me gave high yields of the corresponding adducts in shorter
reaction times (Table 4, entries 1 and 4). The steric effect on the
reaction was also investigated. When 1-naphthylboronic acid or
4-Triphenylamine was employed in the cross-coupling reaction,
the product yields were dramatically decreased, demonstrating
that steric effect of boronic acid was sensitive to the reaction
(Table 4, entries 7-8). It is possible that 2g and 2h are too large to
fit the pore in the Pd-MOF. Further research about the Pd-MOF
catalytic mechanism is undergoing in our laboratory.
cycles. The significant decrease of the catalytic activity was
probably due to the reduction of Pd2+ nodes of MOF [Pd(2-
pymo)2]n and collapse of the MOF structure [11,12,13], and the
decrease of the recovery percent of this catalyst during the
recovery process.
Table 5
Recycling and reuse of the Pd-MOFa
Entry
Catalyst
Fresh
Yield bꢁ%ꢂ
1
2
3
4
5
99
95
90
82
64
First Reuse
Second Reuse
Third Reuse
Fourth Reuse
Table 4
Pd-MOF catalyzed Suzuki-Miyaura cross-coupling reaction of
2-(carboxyethyl) benzendiazonium tetrafluoroborate salt with
arylboronic acids derivativesa
a Reaction conditions: 2-(carboxyethyl)benzendiazonium tetrafluoroborate
salt 1d (0.2 mmol)ꢃphenylboronic acid 2 (0.3 mmol) and 3 mol% catalyst in
b
Methanol solvent (1.0 ml) at 40℃(oil temperature) for 4 hours.
The yield was determined by 1H NMR spectroscopy using 1,3,5-
Trimethoxybenzene as an internal standard.
3. Conclusions
In summaryꢃwe have demonstrated a green and sustainable
method to prepare a series of functionalized biaryls in good to
excellent yields by the Suzuki-Miyaura cross-coupling reaction
of arenediazonium tetrafluoroborate salts and arylboronic acids in
the presence of highly active and easily synthesized Pd-MOF
complex. Reactions were preformed in an open flask without the
aid of any base or additive and using methanol as a green solvent.
This protocol offers a practical, efficient and sustainable catalyst
for Suzuki-Miyaura cross-coupling reaction with the advantages
of good substrate generality, ease of experimental operation and
mild alcoholic reaction conditions without inert-gas protection
and any additional additives (base and ligand). More importantly,
this palladium catalyst shows good to excellent yields towards a
series of arenediazonium tetrafluoroborated salts and can be
simply recovered and reused up to four cycles. This study
indicates that the strategy can serve as a general approach for the
development of Pd-MOF heterogeneous catalyst for practical
catalytic applications. To our delight, this catalyst may find wide
applications in synthetic and medicinal chemistry in industry and
academia. Further work on exploring Pd-MOFs as heterogeneous
catalysts to catalyze more significant cross-coupling reaction is
currently underway.
4. Experimental section
a Reaction conditions: 2-(carboxyethyl)benzendiazonium tetrafluoroborate
salt 1d (1.0 mmol) and Phenylboronic acid 2a-h (1.5 mmol) in methanol
solution (5.0 ml), Pd-MOF (3 mol%), 40 oil temperature.
4.1. General information
Unless otherwise noted, solvents and reagents were analytical
grade and used without further purification. Flash
chromatography was carried out on silica gel (200–300 mesh).
The reusability of heterogeneous catalysts is very important,
especially for commercial application. Thus, we further explored
the catalyst recycling through the Suzuki-Miyaura cross-coupling
of 2-(carboxyethyl) benzenediazonium tetrafluoroborate and
phenylboronic acid under the optimized conditions (Table 5).
The catalyst could be recovered and reused after separation,
washing with MeOH, and drying under vacuum under the same
reaction conditions. Although it could be recycled and reused
three times without a significant reduction in the yield, the
catalyst activity obviously decreased after the fourth consecutive
1
XRD were obtained on a D/max 2200PC X-ray diffraction. H-
NMR and 13C-NMR spectra were recorded on Bruker AVANCE
1
III (500 MHz for H-NMR and 125 MHz for 13C-NMR ), and
chemical shifts were reported in parts per million (ppm, δ)
downfield from internal standard tetramethylsilane. Multiplicities
of signals are described as follows: s --- singlet, d --- doublet, dd
--- doublet d, t --- triplet, m --- multiplet. HRMS were recorded
on solanX 70 FT-MS spectrometer with Methanol as solvent
.

Tetrahedron
5
4.2. General procedure for the synthesis of Biphenyls
methyl [1, 1'-biphenyl]-3-carboxylate 3g: Purified by column
chromatography (petroleum ether/EtOAc, 150/1) as a white
liquid, 82% yield; 1H NMR (500 MHz, Chloroform-d) δ 8.27 (s,
Compounds: 3a-n, 4a-h
1H), 8.00 (d, J = 7.5 Hz, 1H), 7.75 (d, J = 7.5 Hz, 1H), 7.60 (d, J
= 7.5 Hz, 2H), 7.48 (t, J = 8.0 Hz, 1H), 7.43 (d, J = 8.0 Hz, 2H),
7.35 (t, J = 8.0 Hz, 1H), 3.92 (s, 3H). 13C{1H} NMR (125 MHz,
Chloroform-d) δ 167.34, 141.76, 140.40, 131.82, 130.99, 129.18,
129.15, 128.64, 128.56, 128.04, 127.45, 52.48.
To an Aryl diazonium salt derivative (1 mmol) and
Phenylboronic acid derivative (1.5 mmol) at 25 was added Pd-
MOF (3% mmol) and Methanol (5 ml). The reaction mixture was
stirred at 40 (oil temperature) for 2h-23h. After cooling to room
temperature, the mixture was evaporated under reduced pressure.
The residue was purified by silica gel column chromatography to
3a-n, 4a-h. The analytical data of the products are summarized
below.
methyl [1, 1'-biphenyl]-4-carboxylate 3h: Purified by column
chromatography (petroleum ether/EtOAc, 150/1) as a white solid,
74% yield; 1H NMR (500 MHz, Chloroform-d) δ 8.12 (s, 1H),
8.10 (s, 1H), 7.67 (d, J = 8.5 Hz, 2H), 7.65 – 7.61 (m, 2H), 7.47
(t, J = 7.5 Hz, 2H), 7.40 (t, J = 7.5 Hz, 1H), 3.94 (s, 3H). 13C{1H}
NMR (125 MHz, Chloroform-d) δ 167.34, 145.99, 140.36,
130.44, 129.26, 129.08, 128.47, 127.62, 127.39, 52.46.
2-nitro-1, 1'-biphenyl 3i: Purified by column chromatography
(petroleum ether/EtOAc, 100/1) as a pale yellow solid, 70%
yield; 1H NMR (500 MHz, Chloroform-d) δ 7.86 (d, J = 8.0 Hz,
1H), 7.62 (t, J = 7.5 Hz, 1H), 7.51 – 7.39 (m, 5H), 7.33 (d, J = 6.5
Hz, 2H). 13C{1H} NMR (125 MHz, Chloroform-d) δ 149.58,
137.67, 136.59, 132.56, 132.23, 128.96, 128.50, 128.45, 128.17,
124.33.
1, 1'-biphenyl 3a: Purified by column chromatography
(petroleum ether/EtOAc, 300/1) as a white solid, 98% yield; 1H
NMR (500 MHz, Chloroform-d) δ 7.60 (d, J = 7.0 Hz, 4H), 7.45
(t, J = 7.5Hz, 4H), 7.35 (t, J = 7.5 Hz, 2H). 13C {1H} NMR (125
MHz, Chloroform-d) δ 141.57, 129.08, 127.58, 127.49.
4-methyl-1, 1'-biphenyl 3b: Purified by column
chromatography (petroleum ether/EtOAc, 300/1) as a white solid,
70% yield; 1H NMR (500 MHz, Chloroform-d) δ 7.63 – 7.55 (m,
2H), 7.51 – 7.40 (m, 4H), 7.37 – 7.30 (m, 1H), 7.25 – 7.22 (m,
2H), 2.39 (s, 3H). 13C{1H} NMR (125 MHz, Chloroform-d) δ
141.48, 138.68, 137.32, 129.80, 129.03, 127.31, 21.42.
4-ethyl-1, 1'-biphenyl 3c: Purified by column chromatography
(petroleum ether/EtOAc, 300/1) as a white liquid, 75% yield; 1H
NMR (500 MHz, Chloroform-d) δ 7.61 – 7.39 (m, 5H), 7.33 (q, J
= 10.0, 7.3 Hz, 1H), 7.29 – 7.22 (m, 3H), 2.70 (d, J = 6.5 Hz,
2H), 1.27 (t, J = 7.5 Hz, 3H). 13C{1H} NMR (125 MHz,
Chloroform-d) δ 143.71, 141.52, 138.94, 129.03, 128.62, 127.41,
127.34, 127.29, 28.86, 15.93.
4-nitro-1, 1'-biphenyl 3j: Purified by column chromatography
(petroleum ether/EtOAc, 150/1) as a pale yellow solid, 46%
yield; 1H NMR (500 MHz, Chloroform-d) δ 8.30 (d, J = 8.5 Hz,
2H), 7.74 (d, J = 8.5 Hz, 2H), 7.63 (d, J = 7.5 Hz, 2H), 7.53 –
7.43 (m, 3H). 13C{1H} NMR (125 MHz, Chloroform-d) δ 147.94,
147.40, 139.08, 129.47, 129.23, 128.11, 127.69, 124.41.
4-fluoro-1, 1'-biphenyl 3k: Purified by column
chromatography (petroleum ether/EtOAc, 300/1) as a white solid,
70% yield; 1H NMR (500 MHz, Chloroform-d) δ 7.56 (d, J = 7.0
Hz, 4H), 7.45 (t, J = 7.5 Hz, 2H), 7.37 (t, J = 7.5Hz, 1H), 7.15 (t,
J = 8.5Hz, 2H). 13C{1H} NMR (125 MHz, Chloroform-d)
δ162.82 (d, J =243.75 Hz) 140.61, 137.68, 129.05, 127.48,
115.94.
ethyl [1, 1'-biphenyl]-2-carboxylate 3d: Purified by column
chromatography (petroleum ether/EtOAc, 150/1) as a light
1
yellow liquid, 98% yield; H NMR (500 MHz, Chloroform-d) δ
4-chloro-1, 1'-biphenyl 3l: Purified by column
7.83 (d, J = 7.5Hz, 1H), 7.52 (t, J = 7.0 Hz, 1H), 7.44 – 7.28 (m,
7H), 4.12 – 4.03 (m, 2H), 0.99 (t, J = 7.0 Hz, 3H). 13C{1H} NMR
(125 MHz, Chloroform-d) δ 169.04, 142.64, 141.77, 131.60,
130.82, 129.93, 128.63, 128.21, 127.38, 61.11, 13.88.
chromatography (petroleum ether/EtOAc, 300/1) as a white solid,
69% yield; 1H NMR (500 MHz, Chloroform-d) δ 7.57-7.51 (m,
4H), 7.47 – 7.39 (m, 4H), 7.36 (t, J = 7.5 Hz, 1H). 13C {1H}NMR
(125 MHz, Chloroform-d) δ 140.14, 139.83, 133.61, 129.16,
129.13, 128.60, 127.84, 127.20.
ethyl [1, 1'-biphenyl]-3-carboxylate 3e: Purified by column
chromatography (petroleum ether/EtOAc, 150/1) as a yellow
liquid, 70% yield; 1H NMR (500 MHz, Chloroform-d) δ 8.29 (s,
1H), 8.04 (d, J = 7.5 Hz, 1H), 7.78 (d, J = 7.5 Hz, 1H), 7.63 (d, J
= 7.5 Hz, 2H), 7.49-7.42(m, 3H), 7.39 (t, J = 7.0 Hz, 1H), 4.42
(q, J = 7.0 Hz, 2H), 1.42 (t, J = 7.0 Hz, 3H). 13C{1H} NMR (125
MHz, Chloroform-d) δ 166.93, 141.79, 140.55, 131.77, 131.40,
129.21, 129.13, 128.66, 128.57, 128.05, 127.52, 61.42, 14.71.
methyl [1, 1'-biphenyl]-2-carboxylate 3f: Purified by column
chromatography (petroleum ether/EtOAc, 150/1) as a light
yellow liquid, 96% yield; 1H NMR (500 MHz, Chloroform-d) δ
7.81 (d, J = 7.5 Hz, 1H), 7.50 (t, J = 7.5 Hz, 1H), 7.42 – 7.27 (m,
7H), 3.61 (s, 3H). 13C{1H} NMR (125 MHz, Chloroform-d) δ
169.37, 142.72, 141.57, 131.50, 131.13, 130.95, 130.02, 128.56,
128.29, 127.48, 127.41, 52.15.
4-bromo-1, 1'-biphenyl 3m: Purified by column
chromatography (petroleum ether/EtOAc, 300/1) as a white solid,
58% yield; 1H NMR (500 MHz, Chloroform-d) δ 7.58 – 7.53 (m,
4H), 7.47–7.43 (m, 4H), 7.36 (t, J = 7.0 Hz, 1H). 13C{1H} NMR
(125 MHz, Chloroform-d) δ 140.22, 140.08, 132.08, 129.12,
128.90, 127.87, 127.12, 121.79.
4-iodo-1, 1'-biphenyl 3n: Purified by column chromatography
1
(petroleum ether/EtOAc, 300/1) as a white solid, 60% yield; H
NMR (500 MHz, Chloroform-d) δ 7.77 (d, J = 8.5 Hz, 2H), 7.55
(d, J = 7.5 Hz, 2H), 7.44 (t, J =7.5Hz, 2H), 7.35 (dd, J = 7.5, J
=8.5 Hz, 3H). 13C{1H} NMR (125 MHz, Chloroform-d) δ 140.99,
140.33, 138.14, 129.30, 129.21, 128.00, 127.19, 93.38.

Tetrahedron
4
ethyl 4'-methoxy-[1, 1'-biphenyl]-2-carboxylate 4aꢄPurified
by column chromatography (petroleum ether/EtOAc, 60/1) as a
light yellow liquid, 98% yield; 1H NMR (500 MHz, Chloroform-
d) δ 7.79 (d, J = 7.5 Hz, 1H), 7.49 (t, J = 8.0 Hz, 1H), 7.41 – 7.32
(m, 2H), 7.25 (d, J = 8.5 Hz, 2H), 6.93 (d, J = 8.5 Hz, 2H), 4.12
(q, J = 7.0 Hz, 2H), 3.84 (s, 3H), 1.06 (t, J = 7.5Hz, 3H). 13C
{1H}NMR (125 MHz, Chloroform-d) δ 169.14, 159.19, 142.10,
133.98, 131.54, 131.20, 130.80, 129.79, 129.69, 126.94, 113.67,
61.04, 55.40, 14.01.
ethyl 2-(naphthalen-1-yl)benzoate 4gꢄPurified by column
chromatography (petroleum ether/EtOAc, 120/1-60/1) as a light
yellow liquid, 53% yield; 1H NMR (500 MHz, Chloroform-d) δ
8.04 (d, J = 8.0 Hz, 1H), 7.90 – 7.84 (m, 2H), 7.61 (t, J = 7.0 Hz,
1H), 7.55 – 7.43 (m, 4H), 7.43 – 7.30 (m, 3H), 3.77 (dd, J = 7.0,
7.5 Hz, 2H), 0.53 (t, J = 7.0 Hz, 3H). 13C {1H}NMR (125 MHz,
Chloroform-d) δ 168.09, 141.43, 140.24, 133.55, 132.56, 132.34,
132.03, 131.80, 130.38, 128.39, 127.89, 127.74, 126.28, 126.23,
125.98, 125.92, 125.41, 60.83, 13.41.
ethyl 2'-methyl-[1, 1'-biphenyl]-2-carboxylate 4bꢄPurified
by column chromatography (petroleum ether/EtOAc, 60/1) as a
white liquid, 79% yield; 1H NMR (500 MHz, Chloroform-d) δ
7.98 (d, J = 8.5 Hz, 1H), 7.55 (t, J = 8.0 Hz, 1H), 7.45 (t, J = 6.5
Hz, 1H), 7.30 – 7.21 (m, 4H), 7.10 (d, J = 7.5 Hz, 1H), 4.06 (q, J
= 7.0 Hz, 2H), 2.10 (s, 3H), 0.97 (t, J = 7.0 Hz, 3H). 13C{1H}
NMR (125MHz, Chloroform-d) δ 168.13, 142.94, 142.02,
135.74, 131.70, 131.26, 131.10, 130.27, 129.71, 128.90, 127.51,
127.45, 125.51, 61.01, 20.35, 13.91.
ethyl 4'-(diphenylamino)-[1, 1'-biphenyl]-2-carboxylate 4hꢄ
Purified by column chromatography (petroleum ether/EtOAc,
60/1) as a yellow liquid, 37% yield; 1H NMR (500 MHz,
Chloroform-d) δ 7.79 (d, J = 9.0 Hz, 3H), 7.58 (dd, J = 7.0, J
=7.5 Hz, 2H), 7.45 – 7.41 (m, 1H), 7.35 – 7.29 (m, 4H), 7.18 (d, J
= 7.5 Hz, 4H), 7.15 – 7.08 (m, 4H), 4.36 (dd, J = 6.5, J =7.0Hz,
2H), 1.34 – 1.30 (m, 3H). 13C{1H}NMR (125 MHz, Chloroform-
d) δ 152.56 , 147.19 , 132.02 , 129.93 , 129.89 , 129.31 , 126.05 ,
125.01 , 124.66 , 121.55 , 119.08 , 61.62 , 14.74 . HRMS for C27
H23NO2 [M + Na] + calcd: 416. 162100, found: 416.162309.
ethyl 3'-methyl-[1, 1'-biphenyl]-2-carboxylate 4c: Purified by
column chromatography (petroleum ether/EtOAc, 60/1) as a light
yellow liquid, 82% yield; 1H NMR (500 MHz, Chloroform-d) δ
7.83 (d, J = 7.5 Hz, 1H), 7.53 (t, J = 7.5 Hz, 1H), 7.44 – 7.37 (m,
2H), 7.32 – 7.28 (m, 1H), 7.20–7.14 (m, 3H), 4.12 (q, J = 7.5 Hz,
2H), 2.41 (s, 3H), 1.03 (t, J = 7.0 Hz, 3H). 13C{1H} NMR
(125MHz, Chloroform-d) δ 169.17, 142.69, 141.65, 137.73,
131.68, 131.24, 130.77, 129.83, 129.37, 128.15, 128.11, 127.27,
125.75, 61.09, 21.65, 13.92.
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
Thanks for financial support given by National Natural
Science Foundation of China (No. 21602135).
References
ethyl 4'-methyl-[1, 1'-biphenyl]-2-carboxylate 4dꢄPurified
by column chromatography (petroleum ether/EtOAc, 60/1) as a
white liquid, 86% yield; 1H NMR (500 MHz, Chloroform-d) δ
7.80 (d, J = 7.5 Hz, 1H), 7.51 (t, J = 7.5 Hz, 1H), 7.41 – 7.35 (m,
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Highlights
ꢀ A convenient and environmental benign synthesis of a series of functionalized
biaryl derivatives has been demonstrated by a straightforward reaction catalyzed
by the palladium-containing metal-organic framework (Pd-MOF) [Pd
(2-pymo)2]n (2-pymo=2-pyrimidinolate) using methanol as a benign solvent.
ꢀ The present base- and additive-free catalytic reactions proceeded smoothly under
non-anhydrous and non-degassed condition. Such transformation avoided high
reaction temperature, tolerated many functional groups and presented a wide
substrate scope.
ꢀ The palladium catalyst (Pd-MOF) shows good to excellent yields towards a series
of arenediazonium tetrafluoroborated salts and can be simply recovered and
reused up to four cycles.
ꢀ This study indicates that the strategy can serve as a general approach for the
development of Pd-MOF heterogeneous catalyst for practical catalytic
applications. This catalyst may find wide applications in synthetic and medicinal
chemistry in industry and academia.
1