Inorganic Chemistry Communications
Short communication
Synthesis of biaryl compounds via Suzuki homocoupling reactions
catalyzed by metal organic frameworks encapsulated with
palladium nanoparticles
Hong Tanga, Ming Yanga, Xin Lia, Mei-Li Zhoua, Yan-Sai Baoa, Xin-Yu Cuia, Kun Zhaob,
,
Yu-Yang Zhanga *, Zheng-Bo Hana
a College of Chemistry, Liaoning University, Shenyang 110036, PR China
b College of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, PR China
A R T I C L E I N F O
A B S T R A C T
Keywords:
Heterogeneous homocoupling reactions of phenylboronic acids were greatly accelerated via Suzuki homocou-
pling reactions. In this work, a tandem route was designed which firstly one part of phenylboronic acids reacted
with iodine to form iodobenzenes, then another part of phenylboronic acids coupled with iodobenzenes to
produce biaryl compounds. The tandem reaction were catalyzed by a bifunctional heterogeneous catalyst of
metal organic frameworks encapsulated with palladium nanoparticles (Pd@MOFs). This strategy for forming
symmetric C-C bond between benzene rings has obvious advantages such as high efficiency, easy separation,
good recyclability and no addition of toxic halogenated benzene.
Heterogeneous catalysis
Homocoupling reaction
Metal organic frameworks
Palladium nanoparticles
Suzuki reaction
1. Introduction
Therefore, as long as there are two catalytic sites of Pd(0) and Cu(II),
phenylboronic acids could synthesize biaryl compounds via
Iodination-Suzuki tandem reaction.
a
Homocoupling reaction of phenylboronic acids is an important
strategy for forming symmetric C-C bond between benzene rings [1–3].
Symmetrical biaryls are of great significance in versatile applications of
drugs, dyes, agrochemicals, semi-conductor and optically active ligands
[4–7]. Homocoupling reaction of phenylboronic acids catalyzed by
different catalysts has been extensively reported such as Pd(OAc)2 [8],
Cu(BDC) [9], the clay encapsulated Cu(OH)x [10], gold nanoparticles
[2,11], Fe3O4 nanoparticle-supported Cu(II)-β-cyclodextrin complex
[12], and so on. They can be divided into two types. One is a homoge-
neous catalyst such as Pd(OAc)2 reported by Dwivedi et al. [8], which is
difficult to separate and recycle and easy to cause metal pollution. The
other is a heterogeneous catalyst such as Cu(BDC) reported by Puthiaraj
et al. [9], which is not very stable and efficient.
Metal organic frameworks (MOFs) composed of metal ions and
organic linkers have received extensive attention in recent years
[23–26]. Owing to their ordered porous structures, large specific surface
areas and certain chemical and thermal stability, MOFs were widely
used in heterogeneous catalysis, gas storage and separation, drug de-
livery and so on [27–32]. Especially, there are several typical MOFs with
excellent performance and wide application, such as MIL-101(Cr) [33],
UiO-66(Zr) [34], HKUST-1(Cu) [35], ZIF-8(Zn) [36]. All of them are
common carriers for Pd nanoparticles. Pd@HKUST-1 is a ideal bifunc-
tional heterogeneous catalyst that both palladium nanoparticles and
copper ions are evenly and stably distributed on it [31,37]. Porous
structure materials often have better catalytic performance, because the
catalysts with porous structure have larger contact areas with the re-
actants, more exposed catalytic sites, and certain adsorption, as the same
conclusion of Chen and Hou et al. [38,39].
Heterogeneous Suzuki cross-coupling catalysts has been extensively
reported [13–18], due to their highly efficiency and stability. A typical
Suzuki reaction is phenylboronic acid coupled with halogenated ben-
zene, catalyzed by zero-valent palladium complex [19]. Among all of the
halogenated benzenes, iodobenzene is the most suitable for Suzuki re-
action [20]. More importantly, iodobenzenes can be synthesized from
phenylboronic acids catalyzed by various forms of Cu(II) [21,22].
Tandem reactions catalyzed by metal organic frameworks have been
reported widely [40–43]. Based on this, we have designed a new
homocoupling route of phenylboronic acid, using Pd@HKUST-1 as a
bifunctional heterogeneous catalyst. This route is divided into two steps.
* Corresponding author.
Received 13 October 2020; Received in revised form 22 November 2020; Accepted 23 November 2020
Available online 1 December 2020
1387-7003/© 2020 Elsevier B.V. All rights reserved.