Glucopyranoside-Functionalized NHCs-Pd(II)-PEPPSI Complexes: Anomeric Isomerism Controlled and Catalytic Activity in Aqueous Suzuki Reaction

Article abstract of DOI:10.1007/s10562-021-03654-0

The first system controlled anomeric isomerism of glucopyranoside-functionalized N-heterocyclic carbenes based pyridine enhanced precatalyst preparation, stabilization and initiation type palladium(II) complexes (Glu-NHCs-Pd(II)-PEPPSI, 2a–d) were prepare

Full text of DOI:10.1007/s10562-021-03654-0

Catalysis Letters
https://doi.org/10.1007/s10562-021-03654-0
Glucopyranoside‑Functionalized NHCs‑Pd(II)‑PEPPSI Complexes:
Anomeric Isomerism Controlled and Catalytic Activity in Aqueous
Suzuki Reaction
Zhonggao Zhou1 · Qian Xie1 · Jing Li1 · Yangyang Yuan1 · Yong Liu1 · Yulong Liu1 · Dongliang Lu1 · Yongrong Xie1
Received: 24 January 2021 / Accepted: 9 May 2021
© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2021
Abstract
The frst system controlled anomeric isomerism of glucopyranoside-functionalized N-heterocyclic carbenes based pyridine
enhanced precatalyst preparation, stabilization and initiation type palladium(II) complexes (Glu-NHCs-Pd(II)-PEPPSI, 2a–d)
were prepared and fully characterized. It is interesting to note that pure β–anomer PEPPSI complex 2d was obtained, in which
the Glu-substituent connects to the imidazole heterocycle ring N through ethoxy bridged anomeric carbon. In addition, the
catalytic activities revealed that Glu-NHCs-Pd(II)-PEPPSI complexes 2a-d are efcient catalysts for the aqueous Suzuki
reaction. Under optimized conditions, a series of fuorene-cored functional materials with diferent aryl-substituents were
synthesized through the Suzuki reaction with excellent yields. The Glu-NHCs-Pd(II)-PEPPSI complex containing bulky
and rigid 2,5-dimethylphenyl group played an important role in maintaining the β conformation and improving the catalytic
activity signifcantly.
Graphic Abstract
Keywords Carbohydrate · N-heterocyclic carbenes · PEPPSI type catalyst · Aqueous suzuki reaction · Green chemistry
* Zhonggao Zhou
1 Introduction
zhgzhou@foxmail.com
* Yongrong Xie
Rational catalyst design incorporating palladium N-heter-
yongrongxie@foxmail.com
ocyclic carbenes (NHCs) complexes has taken center stage
1
[1–4]. Thereby, extensive eforts have been committed to
the synthesis of the biaryl fragments, including the Negishi,
Hiyama, Ullmann, Kumada, Stille, and Suzuki reactions
Key Laboratory of Jiangxi University for Functional
Materials Chemistry, College of Chemistry and Chemical
Engineering, Gannan Normal University, 341000 Ganzhou,
People’s Republic of China
Vol.:(0123456789)
1 3

Z. Zhou et al.
[5–8]. Among the carbon–carbon couplings, the Suzuki
reaction has been recognized as one of the most workable
methods for building the biaryl fragments [9–13]. A number
of novel homogeneous catalysts, heterogeneous catalysts or
supported palladium composites have been developed for
the Suzuki reactions in recent decades [14, 15]. Conjugate
organic functional small molecule and polymer materials
(COFM) containing fuorene, spirofuorene, triphenylamine
and carbazole substituents have attracted extensive atten-
tion in the felds of organic photovoltaic (OPV), organic
light-emitting diodes (OLED), and perovskite solar cells
(PVSCs), etc. [16–21]. Generally, many catalytic systems
for the construction of COFM have been developed, includ-
ing Pd/phosphine catalyst [22]. However, nearly all Pd/phos-
phine catalysts were combined with harsh reaction condi-
tions [23–26]. The electronic donor properties of NHCs are
similar to phosphines, and frequently regarded as phosphines
analogues [27–31]. Generally, complexes of the metal with
NHCs are kinetically robust, making NHCs potentially supe-
rior star ligands in catalysts [8, 32–34]. To accomplish high
reactivity in the Suzuki reaction, numerous homogeneous
Pd/NHCs catalyst has been designed. It was obviously to see
the positive infuence of bulky NHC ligands on the Suzuki
reaction process [35, 36]. Among them, pyridine enhanced
precatalyst preparation, stabilization and initiation (PEPPSI)
Pd complexes were proved to be good catalyst [37–39]. Liu
and Zeng found that the halogen groups on the pyridine of
Pd-PEPPSI complexes were efcient for the Suzuki reac-
tion of aryl chlorides [38, 39]. Aktas and co-workers used
2-hydroxyethyl-substituted Pd-PEPPSI complexes for the
high reactivity Suzuki reaction of aryl chlorides in aqueous
media [40].
ligand for Pd-catalyzed cross coupling over the last few
years, including phosphines and NHCs ligands [58–62].
Therefore, based on our previous research, we want to sys-
tematically study anomeric isomerism of Glu-NHCs-Pd(II)-
PEPPSI complexes, in which the Glu-substituent connects
to the imidazole heterocycle ring nitrogen through ethoxy
bridged anomeric carbon.
With this background, in this paper, four air-stable,
handle-friendly Pd(II)-PEPPSI type precatalysts (2a-d)
constituted by Glu-NHCs have been synthesized and char-
acterized. Specifcally, complexes 2a-d were conveniently
synthesized from their respective Glu-functionalized imida-
zolium bromide salts by directly combined with Pd(OAc)2 in
pyridine. Through control the bulky and rigid of substituent
carefully, it is interesting to note that pure β-anomer PEPPSI
complex 2d was obtained. To the best of our knowledge,
this is the frst example of system controlling absolute con-
fguration of anomeric carbon through bridging group using
the steric efects of substituents. The catalytic properties of
these Glu-NHCs-Pd(II)-PEPPSI complexes (2a-d) in aque-
ous Suzuki reaction are also described, a series of fuorene-
cored functional materials (22 examples) were synthesized
through the Suzuki reaction with excellent yields.
2 Results and Discussion
Herein, D-glucose was used as an initiator for the synthesis
of the desired Glu-functionalized NHCs precursor 1a-d in
three steps [62, 63]. Then, four Glu-NHCs-Pd(II)-PEPPSI
type precatalysts 2a-d have been synthesized by direct reac-
tion of 1a-d with Pd(OAc)2 in pyridine with the isolate
yields above 80% (Scheme 1). The addition of KBr will
favour a complete halogen-coordinated exchange and thus
to the production of a pure product. The complexes 2a-d
has been characterized by electrospray mass spectrometry
(ESI–MS), fourier-transform infrared spectroscopy (FT-IR),
Carbohydrate (Car-) is ubiquitous in nature and this of
low cost and biocompatible [41]. The Car-motifs are bulky,
water solubility and possess multiple chiral carbons [42].
Incorporation of Car-motifs into metal complexes afords
them these superior features, which are utilized for drug
delivery, catalysts, and sensors [41–43]. Only few exam-
ples dealing with Car-functionalized NHCs ligands, and Ag,
Au, Ir, Ru, Rh, Ni, Pd, Pt complexes have been reported
[44–52]. Related researches with Car-functionalized NHCs
and NHCs-metal complexes have been reviewed [53–57].
Anchoring Car-motifs to the NHCs metal complexes via
C1 carbon (anomeric carbon) could provide a bulky steric
hindrance and possibly afect its steric conformation and
its catalytic properties [46, 47]. However, when a C1 is
connected to an imidazole heterocycle N directly, α and
β-glucosides (Glu-) can be obtained, and the absolute con-
formation of metal complexes is difcult control with the
other substituents [45]. In addition, the discipline of absolute
conformation of Glu-NHCs and Glu-bridging NHCs coordi-
nation metal complexes has not been systematically studied.
Our laboratory has developed a series of Car-functionalized
1
and H and 13C NMR spectroscopy. The FT-IR data evi-
dently indicated that complexes 2a-d exhibit a characteristic
v(NCN) band generally between 1360 and 1450 cm−1(Figure
S6). The complexes 2a-d are hygroscopic and air stable, the
disappearance of the imidazole heterocycle 2-position pro-
ton (NCHN) 1H NMR peaks in 1a-d (9.27–10.15 ppm) con-
frms the Glu-NHCs generated [62]. The 1H NMR signals of
the imidazole heterocycle 3,4-position proton (NCHCHN)
of 2a-d shift about 0.6 ppm upfeld compared to the chemi-
cal shifts of their corresponding imidazolium bromide salts
1a-d. The 13C NMR of 2a-d showed the carbene carbon
(NCN) bound to Pd metal (NCN–Pd) resonances appearing
at 152.2–152.5 ppm and are comparable to that described
in other reported NHC-Pd complexes (145–175 ppm) [48].
The NCN signal of 2a (152.2 ppm) appears around 30 ppm
downfeld relative to the corresponding NCHN signal for the
1 3

Glucopyranoside‑Functionalized NHCs‑Pd(II)‑PEPPSI Complexes: Anomeric Isomerism…
AcO
HO
AcO
OAc
OAc
OH
OH
OAc
AcO
AcO
HO
HO
AcO
AcO
Br
O
O
O
N
O
R*
N
R
AcO
KBr
OAc
N
Under N2
100 oC, 12 h
> 80%
AcO
AcO
N
R
Br Pd Br
N
Pd(OAc)2
N
O
O
Br
1a-d
2a-d
Me
Me
O
Me
O
R
OAc
R*
OAc
OAc
Me
AcO
a
b
c
d
Scheme 1 Synthesis of Glu-NHCs-Pd(II)-PEPPSI complexes
we found a less fexible and bulkier substituent around the
Pd metal probably contributed to the formation of mixture
isomers (2a, 2b and 2c). In order to further study, we choose
the bulky and rigid 2,5-dimethylphenyl group next, which
may restrict the rotation of the Glu-NHCs ligand around the
Pd metal center. It is interesting to note that only one set
1
of H NMR signal of complex 2d was obtained, suggest-
ing maintain pure β-anomer in solution (Figure S5). The
crystals of complex 2a suitable for X-ray structural analysis
were obtained by slow difusion of petroleum ethers into a
concentrated methanol solution.
Complex 2a crystallizes in the form of yellow rods in a
monoclinical unit cell. The molecular structure of complex
2a is depicted in Fig. 2. Complex 2a adopts P212121 symme-
try in the solid state. The C(1)-Pd(1)-N(3) and Br(1)-Pd(1)-
Br(2) angles of 178.7(2)° and 177.19(3)° for complex 2a, are
in accordance with the expectation 180° for a square plane
geometry. The Pd(1)-C(1) bond distances of 1.962(4) Å,
and Pd(1)-N(3) bond distances of 2.102(4) Å, respectively,
are consistent with those found in analogous NHCs based
Pd(II)-PEPPSI based PEPPSI complexes [37–40].
Fig. 1 The α and β isomers ratio of Glu-NHCs-Pd(II)-PEPPSI com-
plex 2a-d in CDCl3
imidazolium bromide salt 1a, and those of 2b (152.5 ppm),
2c (152.4 ppm) and 2d (152.2 ppm) shift about 30~31 ppm
downfeld.
Recently, the catalytic activities of NHCs-Pd(II)-PEPPSI
complexes in Suzuki reactions in aqueous media have been
investigated [38, 40]. In the other part of our study, we eval-
uated the catalytic activity of Glu-NHCs-Pd(II)-PEPPSI
precatalysts 2a-d catalyst system in Suzuki reaction. We
initially investigated Glu-NHCs-Pd(II)-PEPPSI complex
2a catalyzed Suzuki reaction between phenylboronic acid
and 4-bromotoluene provide 4-methylbiphenyl in 80%
yield after refux in ethanol for 1 h, without the detection
of dehalogenated and homo-coupling products (Table 1,
Two sets of NMR signals of complex 2a-c attributed to α
and β isomers are observed in CDCl3 (Fig. 1, Figure S1-S4),
the results were in line with the literature [48]. Since the
electronic properties of the complexes 2a and 2b are quite
similar, and the relative ratios of α and β isomers are 0.20:1,
1
and 0.17:1 from the H NMR (Figure S5). Because of the
greater steric efect, smaller ratio of α and β isomers was
observed (0.036:1 in 2c, Figure S5). From the results above,
1 3

Z. Zhou et al.
Fig. 2 The X-ray structure
of Glu-NHCs-Pd(II)-PEPPSI
complex 2a
Table 1 The
Suzuki
acid
reaction
and
between
phe-
was obtained in the presence of commercial PdCl2 without
ancillary ligand (Table 1, entry 6) and trace product was
obtained without any catalyst was added (Table 1, entry 7).
Further decrease in the amount of 2d to 0.005~0.03 mol%
displayed inferior results (Table 1, entries 8–10), through
prolong the reflux time to 3 h, the isolated yield was
improved to 96% with 0.005 mol% catalyst (Table 1, entry
10). These experiments revealed that the bulky and rigid
2,5-dimethylphenyl in Glu-NHCs-Pd(II)-PEPPSI complex
2d play important role in the elevating catalytic activity of
Pd catalytic species.
nylboronic
4-bromotoluenea
Entry
Catalyst
Amount of cat. Time (h)
Yield (%)b
(mol%)
1
2
3
4
5
6
7
2a
2b
2c
2d
0.05
0.05
0.05
0.05
1.5 (0.05)
0.1
1
1
1
1
1
1
1
1
1
3
80
85
88
99
PdCl2/1d
75 (60)
20
Then the Suzuki reaction was carried out in a series of
PdCl2
–
i
n
green solvents, including H2O, MeOH, PrOH, BuOH,
EtOH (95%), and EtOH/H2O mixed solvent, resulting in
good to excellent yields (Table 2, entries 1–9). Among the
solvents investigated, EtOH/H2O (v/v = 3:1) was the best
choice (Table 2, entry 9), in line with the result observed
by Del Zotto and co-workers [64]. Upon further evaluat-
ing the Suzuki reaction conditions via variation of the base
(Table 2, entries 11–17), commonly used organic base
KOBut, NaOBut, NaOMe and Et3N were found not to be the
best suitable for the Suzuki reaction herein (Table 2, entries
12–15). The inorganic weak base K2CO3 was confrmed as
the most efcient choice and 97% yield was obtained even
reduces the reaction time to 0.5 h (Table 2, entries 8 and 9).
We also found that without or with other base K3PO4·7H2O
and Na2CO3 cannot aford ideal yields (Table 2, entries 11,
16 and 17). The catalytic activities of our catalytic system
is only moderate among the reported NHCs-Pd(II)-PEPPSI
catalysts [40].
–
Trace
94
93
8
9
10
2d
0.03
0.01
0.005
2d
2d
96
aReaction conditions: 4-bromotoluene (1.0 mmol), phenylboronic
acid (1.5 mmol), K2CO3 (2.0 mmol), ethanol (3.0 mL), 90 °C oil bath
under N2
bIsolated yield
entry 1). Encouraged by this positive result, various Glu-
NHCs-Pd(II)-PEPPSI complexes 2b-d were investigated
for this cross coupling. As shown in Table 1, catalyst 2d
was observed to provide an excellent result with 99% yield
(Table 1, entry 4), but catalyst 2b and 2c with non/smaller
bulky butyl or phenyl substituents displayed inferior results
(Table 1, entries 2 and 3, 85% and 88%), indicating the
bulky and rigid backbone has signifcant infuence on the
catalytic activity. In the presence of 1.5 mol% of PdCl2/1d
(mol:mol = 1:2), 75% of 4-methylbiphenyl was obtained
after 1 h, and 60% yield was obtained with 0.05 mol% of
PdCl2/1d (mol:mol=1:1), the result was written in brackets
(Table 1, entry 5). By contrast, only 20% yield of product
The optimized reaction parameters were identifed as fol-
lows: aryl halide (1.0 mmol), arylboronic acid (1.5 mmol),
Glu-NHCs-Pd(II)-PEPPSI complex 2d (0.01 mol%) catalyst
were stirred in EtOH/H2O (v/v=3:1) for 0.5 h in the pres-
ence of K2CO3 (2.0 mmol) in 90 °C oil bath under nitrogen.
1 3

Glucopyranoside‑Functionalized NHCs‑Pd(II)‑PEPPSI Complexes: Anomeric Isomerism…
Table 2 The Suzuki reactions with diferent solvents and basesa
wide range of arylboronic acids bearing either an electron-
rich or an electron-poor substituent proceeded smoothly and
delivered the target products in excellent yields (3f-z, 22
examples, Fig. 3). As expected, the product 3f could be iso-
lated in 96% yield with 2-bromo-9H-fuorene, and just 33%
isolated yield obtained using 2-chloro-9H-fuorene. Subse-
quently, using 2-methylphenyl boronic acid, 3,5-dimethyl-
phenyl boronic acid and 2,6-dimethylphenyl boronic acid
take the place of phenyl boronic acid, the couplings were
completed with yield above 91% yield (3f, 3 g, 3r, 3t and
3 s, Fig. 3). When increasing the steric hindrance of phenyl
boronic acid, the yield decreased slightly. Moreover, elec-
tron-poor 3,5-difuorophenyl boronic acid, 3,4,5-trifuoro-
phenyl boronic acid aforded the desired product with yield
above 98% and 97% yield (3i, 3j, 3w and 3x, Fig. 3). Overall,
we note that nearly quantitative isolate yield of products
were aforded when using a series arylboronic acids as the
coupling reactant herein (Fig. 3).
Entry
Base
Solvent
Yieldb
1
2
3
4
5
6
7
8
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K3PO4·7H2O
KOBut
Et3N
H2O
MeOH
iPrOH
nBuOH
40
88
85
87
94
96
98
99
97c
92
90
89
75
88
91
83
Trace
EtOH (95%)
EtOH/H2O=1/1
EtOH/H2O=2/1
EtOH/H2O=3/1
EtOH/H2O=3/1
EtOH/H2O=4/1
EtOH/H2O=3/1
EtOH/H2O=3/1
EtOH/H2O=3/1
EtOH/H2O=3/1
EtOH/H2O=3/1
EtOH/H2O=3/1
EtOH/H2O=3/1
9
10
11
12
13
14
15
16
17
NaOMe
NaOBut
Na2CO3
–
The recyclability of the best catalyst 2d (0.01 mol%)
was further investigated in the coupling of 4-iodotoluene
and phenylboronic acid using K2CO3 as base in EtOH/H2O
(v/v = 3:1). The product 4-methylbiphenyl is very easy to
separate, just using petroleum ether hexane and ethyl ace-
tate with simple extraction. The EtOH/H2O (v/v=3:1) polar
aqueous solution, which contained catalyst 2d, was easily
recycled. The catalyst 2d was retained in the aqueous solu-
tion layer, which could be recycled directly, and the results
were presented in Table 3. It can be seen from the result, the
catalytic activity of catalyst 2d started to slightly reduce after
the third run (Table 4, entry 3). An excellent yield can be
obtained after extension of reaction time (Table 4, entry 5).
aReaction conditions: 4-bromotoluene (1.0 mmol), phenylboronic
acid (1.5 mmol), 2d (0.01 mol%), base (2.0 mmol), solvent (3.0 mL),
90 °C oil bath for 1.0 h under N2
bIsolated yield
cReaction for 0.5 h
Comparing with the best result of other reported used
carbohydrate based NHCs-Pd(II) catalysts in Suzuki reaction
(Table 3), our catalysts are easily synthesized, simultane-
ously, pure β-anomer Glu-NHCs-Pd(II)-PEPPSI complex
2d was obtained for the frst time, additionally, our catalytic
system with complex 2d is less time consuming, more ef-
cient, lower catalyst loading and additive-free for the Suzuki
reaction (Table 3).
3 Conclusion
With the optimal Suzuki reaction condition in hand, we
set out to investigate the substrate scope of the reaction. As
shown in Fig. 3, the model product 3a could be isolated in
99%, 97%, and 38% yields with 4-iodotoluene, 4-bromotolu-
ene and 4-chlorotoluene respectively. Aryl bromides with
electron-donating and electron-withdrawing substituents
could aford the biaryl derivatives in excellent yields (3b-
d, 95–98%, Fig. 3). To our delight, activated aryl chloride
p-(trifuoromethyl)chlorobenzene could gave 3e without
increase the amount of catalyst (3e, 93%, Fig. 3).
In summary, four Glu-NHCs-Pd(II)-PEPPSI complexes
have been synthesized and used as efective catalysts for
Suzuki reaction of aryl bromides and activated aryl chlo-
rides in green solvent. We found a fexible and less bulkier
substituent around the Pd metal contributed to the formation
of α and β isomers, the 2,5-dimethylphenyl group on the
NHCs heterocycle N atom provides ideal electronic proper-
ties paired with rigid and bulky surrounding of the Pd metal
center restrict the rotation of the anomeric carbon, and ren-
ders the pure β-anomer. A wide range of arylboronic acids
underwent the Suzuki reaction with 2-bromo-9H-fuorene
or 2,7-dibromo-9H-fuorene to provide excellent yields of
the corresponding products. Moreover, this EtOH/H2O-
involved protocol is in line with the idea of green chemistry
and industrial application, simultaneously, is of huge interest
for the preparation of conjugated organic small molecules
materials.
Since both of K2CO3 as base and EtOH/H2O as solvent
are highly suitable for industrial applications, the poten-
tial of Glu-NHCs-Pd(II)-PEPPSI complex 2d was further
explored. COFM containing triphenylamine, fuorine and
carbazole functional groups have obviously attracted atten-
tion in the feld of OPV, OLED and PVSCs [20, 21, 69, 70].
The cross-couplings between 2-bromo-9H-fluorene,
2-chloro-9H-fuorene and 2,7-dibromo-9H-fuorene with a
1 3

Z. Zhou et al.
Table 3 The best result of carbohydrate based NHCs-Pd complexes catalyzed Suzuki reactions
Entry
Amount cat. (mol%) X=Br, Cl
Time (h)
Additive
Yield (%)
References
1
2
3
4
5
6
7
8
0.01
0.5
0.0001
0.01
0.01
0.1
0.1
0.05
0.1
Br
Cl
Br
Br
Cl
Br
Cl
Br
Cl
Br
Cl
16
17
16
16
16
0.5
17
15
15
1
/
98
53
80
98
10
96
57
99
86
96
93
[65]
[65]
[66]
[67]
[67]
[68]
[68]
[48]
TBAB
/
/
/
/
TBAB
/
TBAB
/
/
9
10
11
[48]
This work
This work
0.005
0.01
6
CH-Glu), 4.32 (m, 3H, CH-Glu and CH2), 4.51 (d, J=8.0 Hz,
1H, CH-Glu), 4.98 (m, 2H, CH-Glu), 5.05 (t, J=8.0 Hz, 1H,
CH-Glu), 5.15 (t, J=8.0 Hz, 1H, CH-Glu), 6.89 (d, J=2.0 Hz,
1H, CH-Imidazole), 6.97 (d, J=2.0 Hz, 1H, CH-Imidazole),
7.34 (m, 2H, CH-Pyridine), 7.76 (m, 1H, CH-Pyridine), 8.99
(m, 2H, CH-Pyridine). 13C NMR (101 MHz, CDCl3), δ 20.5
(CH3), 20.7 (CH3), 20.8 (CH3), 20.9 (CH3), 38.3 (CH3), 50.8
(CH2-CH2), 60.3 (CH-Glu), 61.7 (CH2-CH2), 68.2 (CH-
Glu), 68.8 (CH-Glu), 71.1 (CH-Glu), 72.6 (CH-Glu), 100.6
(CH-Glu), 122.4 (C-Imidazole), 123.9 (C-Imidazole), 124.5
(C-Pyridine), 124.9 (C-Pyridine), 147.5 (C-Pyridine), 152.4
(NCN-Pd), 169.2 (C=O), 169.3 (C=O), 170.0 (C=O), 170.6
(C=O). FT-IR (cm−1): 3475, 2965, 2872, 1757, 1602, 1471,
1445, 1375, 1235, 1159, 1067, 1055, 904, 772, 739, 685. MS
(ESI): m/z (%)=802.9 (100) [M+1]+.
4 Experimental Section
4.1 Typical Procedure for the Synthesis
of Glu‑NHCs‑Pd(II)‑PEPPSI Themed Complexes
2a‑d
The Glu-NHCs-Pd(II)-PEPPSI complexes 2a-d was synthe-
sized according to a modifed previously reported method
[37]. The solution of a specifc Glu-NHCs precursor 1a-d
(1.0 mmol), KBr (2.0 mmol) and Pd(OAc)2 (1.0 mmol) in
dry pyridine (3.0 mL) was refuxed for 12 h with vigor-
ous stirring. The resulting complexes 2a-d was purifed by
column chromatography (dichloromethane/methanol, 30:1
to 20:1).
4.2 [1‑(2‑β‑D‑glucopyranosyloxyethyl)‑3‑methyl‑im
idazol‑ylidene]Pd(pyridine)Br2
4.3 [1‑(2‑β‑D‑glucopyranosyloxyethyl)‑3‑butyl‑imid
azol‑ylidene]Pd(pyridine)Br2
Yellow crystalline solid, 87%. 1H NMR (400 MHz, CDCl3),
δ 1.95 (s, 3H, CH3), 1.97 (s, 3H, CH3), 1.99 (s, 3H, CH3),
2.08 (s, 3H, CH3), 4.07 (s, 3H, CH3), 4.10 (t, J=8.0 Hz, 1H,
1
Yellow crystalline solid, 90%. H NMR (400 MHz,
CDCl3), δ 1.01 (t, J=7.6 Hz, 3H, CH3), 1.23 (t, J=7.2 Hz,
1 3

Glucopyranoside‑Functionalized NHCs‑Pd(II)‑PEPPSI Complexes: Anomeric Isomerism…
Ar
Br
Me
3a
MeO
Ar-B(OH)2
Me
R
R
2d
(0.01 mol%)
R
R
, 10 min, 99% (X = I)
3a
3c
, 95% (X = Br)
3b
, 97% (X = Br)
, 98% (X = Br)
K2CO3
, 97% (X = Br)
, 12 h, 38% (X = Cl)
MeOC
3d
CF3
F3C
3e
EtOH/H2O=3:1
OFMs 3
90 oC
3a
28 examples
38%, 91-99%
0.5 h
, 6 h, 93% (X = Cl)
F
Ar
Br
Me
Me
CF3
F
Me
Me
3h
, 97%
3i
, 98%
3f
, 33% (X = Cl)
3g
, 92%
F
NO2
3f
, 96%
CF3
F
F
3j
3k
, 96%
3l
3m
, 98%
, 97%
, 95%
O
Ph
O
O
O
N
Ph
Et
O
Ph
3n
3o
3p
3q
, 93%
, 96%
Me
, 97%
, 97%
Me
Me
Me
Me
Me
Me
Me
Me
Me
3r
3s
3v
3t
, 91%
, 94%
, 92%
, 96%
F3C
CF3
F
F
F3C
CF3
F
F
3u
3w,
98%
, 92%
F
F
O
O
Ph
Ph
F
F
C
C
N
N
EtO
OEt
Ph
Ph
F
F
3x
3y
3z
, 96%
, 96%
, 93%
Fig. 3 The substrate scope for the synthesis of biphenyl and fuorine-cored COFMs (28 examples)
4H, CH2), 1.46 (m, 2H, CH2), 1.94 (s, 3H, CH3), 1.97
(s, 3H, CH3), 1.99 (s, 3H, CH3), 2.02 (s, 3H, CH3), 2.07
(s, 3H, CH3), 3.69 (m, 1H, CH-Glu), 4.10 (m, 2H, CH2),
4.23 (m, 1H, CH-Glu), 4.29 (m, 1H, CH-Glu), 4.42 (m,
3H, CH-Glu and CH2), 4.52 (m, 1H, CH-Glu), 4.98 (m,
2H, CH2), 5.05 (t, J = 10.0 Hz, 1H, CH-Glu), 5.15 (t,
J=9.2 Hz, 1H, CH-Glu), 6.87 (d, J=2.0 Hz, 1H, CH-Imi-
dazole), 6.98 (d, J = 2.0 Hz, 1H, CH-Imidazole), 7.32 (m,
2H, CH-Pyridine), 7.75 (m,1H, CH-Pyridine), 8.99 (m,
2H, CH-Pyridine). 13C NMR (101 MHz, CDCl3), δ 13.8
(CH3), 14.2 (CH2), 19.9 (CH2), 20.6 (CH3), 20.7 (CH3),
20.8 (CH3), 21.0 (CH3), 32.1 (CH2), 51.0 (CH2-CH2), 60.4
(CH-Glu), 61.8 (CH2-CH2), 68.9 (CH-Glu), 71.1 (CH-
Glu), 71.7 (CH-Glu), 72.7 (CH-Glu), 100.7 (CH-Glu),
121.0 (C-Imidazole), 124.0 (C-Imidazole), 124.6 (CH-
Pyridine), 137.9 (CH-Pyridine), 146.8 (CH-Pyridine),
152.5 (NCN-Pd), 169.3 (C = O), 169.4 (C = O), 170.1
(C = O), 170.7 (C = O). FT-IR (cm−1): 3478, 2957, 2872,
1757, 1602, 1569, 1445, 1428, 1370, 1221, 1168, 1067,
1039, 907, 758, 688. MS (ESI): m/z (%) = 844.8 (100)
[M + 1]+.
1 3

Z. Zhou et al.
Table 4 Reusability of the catalyst in the Suzuki reactiona
J = 2.0 Hz, 1H, CH-Imidazole), 7.16 (m, 4H, CH-Pyri-
dine and CH-Benzene), 7.19 (d, J = 2.0 Hz, 1H, CH-Imi-
dazole), 7.27 (t, J = 8.0 Hz, 1H, CH-Pyridine), 7.60 (m,
1H, CH-Pyridine), 8.66 (m, 2H, CH-Pyridine). 13C NMR
(101 MHz, CDCl3), δ 19.6 (CH3), 19.7 (CH3), 20.3 (CH3),
20.5 (CH3), 20.6 (CH3) 20.8 (CH3), 51.4 (CH2-CH2), 61.5
(CH2-CH2), 68.0 (CH-Glu), 68.6 (CH-Glu), 71.0 (CH-
Glu), 71.6 (CH-Glu), 72.5 (CH-Glu), 100.3 (CH-Glu),
123.5 (C-Imidazole), 123.7 (C-Benzene), 124.1 (C-Imi-
dazole), 128.3 (C-Pyridine), 128.4 (C-Pyridine), 129.2
(C-Pyridine), 136.3 (C-Benzene), 136.4 (C-Benzene),
137.5 (C-Benzene), 149.4 (C-Benzene), 152.2 (NCN-
Pd), 169.0 (C = O), 169.2 (C = O), 169.8 (C = O), 170.3
(C = O). FT-IR (cm−1): 3495, 2920, 2868, 1754, 1644,
1602, 1446, 1428, 1367, 1224, 1171, 1064, 1036, 907,
778, 755, 694. MS (ESI): m/z (%) = 892.9 (100) [M + 1]+.
Run
Time (min)
Conversionb
Yield (%)c
1
2
3
4
5
10
10
10
10
30
100
99
97
95
100
98
98
95
93
99
aReaction conditions: 4-iodotoluene (2.0 mmol), phenylboronic acid
(3.0 mmol), catalyst 2d (0.01 mol%), K2CO3 (4.0 mmol), EtOH/H2O
(v/v=3:1, 12.0 mL), 90 °C oil bath
bMeasured by GC–MS
cIsolated yield
4.4 [1‑(2‑β‑D‑glucopyranosyloxyethyl)‑3‑phenyl‑im
idazol‑ylidene]Pd(pyridine)Br2
Yellow crystalline solid, 92%. 1H NMR (400 MHz, CDCl3),
δ 2.00 (s, 3H, CH3), 2.01 (s, 3H, CH3), 2.02 (s, 3H, CH3),
2.09 (s, 3H, CH3), 3.72 (m, 1H, CH-Glu), 4.12 (m, 3H, CH-
Glu and CH2), 4.28 (m, 1H, CH-Glu), 4.41 (m, 1H, CH-
Glu), 4.50 (m, 1H, CH-Glu), 4.60 (m, 2H, CH2), 5.12 (m,
4H, CH-Glu and CH2), 7.14 (d, J=2.0 Hz, 4H, CH-Pyridine
and CH-Benzene), 7.18 (d, J=2.0 Hz, 1H, CH-Imidazole),
7.26 (m, 2H, CH-Pyridine and CH-Benzene), 7.48 (d,
J=8.0 Hz, 1H, CH-Imidazole), 7.56 (d, J=8.0 Hz, 2H, CH-
Benzene), 7.70 (m, 1H, CH-Benzene), 8.00 (m, 2H, CH-
Pyridine), 8.82 (m, 2H, CH-Pyridine). 13C NMR (101 MHz,
CDCl3), δ 20.5 (CH3), 20.8 (CH3), 20.9 (CH3), 21.0 (CH3),
51.3 (CH2-CH2), 61.8 (CH2-CH2), 68.3 (CH-Glu), 68.8 (CH-
Glu), 71.2 (CH-Glu), 71.8 (CH-Glu), 72.7 (CH-Glu), 100.8
(CH-Glu), 122.5 (C-Imidazole), 124.5 (C-Benzene), 126.4
(C-Imidazole), 128.8 (C-Pyridine), 129.3 (C-Pyridine),
129.9 (C-Pyridine), 137.8 (C-Benzene), 139.5 (C-Benzene),
148.8 (C-Benzene), 151.9 (C-Benzene), 152.4 (NCN-Pd),
169.4 (C=O), 169.5 (C=O), 170.1 (C=O), 170.7 (C=O).
FT-IR (cm−1): 3394, 2920, 2850, 1754, 1647, 1602, 1560,
1499, 1428, 1367, 1224, 1168, 1065, 1039, 904, 764, 694.
MS (ESI): m/z (%)=864.7 (100) [M+1]+.
4.6 General procedure for the Suzuki reaction
catalyzed by Glu‑NHCs‑Pd(II)‑PEPPSI complexs
2a‑d
Degassed EtOH/H2O (v/v = 3:1, 3.0 mL) was transfer to a
fask with the corresponding amount of K2CO3 (2.0 mmol),
Glu-NHCs-Pd(II)-PEPPSI complex (0.01 mol%), then
stirred for about 5 min under N2 atmosphere, 4-bromo-
toluene (1.0 mmol), phenylboronic acid (1.5 mmol) was
sequentially added, the reaction solution was kept at 90 °C
and stirred for the corresponding time shown in Tables 1, 2
and Fig. 2. The mixture was diluted with 3.0 mL of dichlo-
romethane, and then washed with brine. The organic layer
was collected and dried over MgSO4. The organic solvent
was concentrated in vacuum, and the product was purifed
by fash chromatograph.
Supplementary Information The online version contains supplemen-
tary material available at https://doi.org/10.1007/s10562-021-03654-0.
Acknowledgements This work was financially supported by the
National Natural Science Foundation of China (No. 21562002), the
Funding Project for Academic and Technical Leaders of Jiangxi Prov-
ince (No. 20172BCB22021), Education Department of Jiangxi Prov-
ince (No. GJJ201427, GJJ201424) and Graduate Innovation Fund of
Gannan Normal University (No. YCX20A008).
4.5 [1‑(2‑β‑D‑glucopyranosyloxyethyl)‑3‑(2,5‑dimet
hylphenyl)‑imidazol‑ylidene]Pd(pyridine)Br2
Code Availability CCDC Deposition Number 2069632 contains the
supplementary crystallographic data for this paper. These data can
be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif,
or by emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ, UK.
Yellow crystalline solid, 95%. 1H NMR (400 MHz, CDCl3)
δ 1.95 (s, 3H, CH3), 1.96 (s, 3H, CH3), 1.97 (s, 3H, CH3),
1.98 (s, 3H, CH3), 2.25 (s, 3H, CH3), 2.28 (s, 3H, CH3),
3.72 (m, 1H, CH-Glu), 4.06 (q, J = 18.0 Hz, 2H, CH2),
4.09 (dd, J1 = 8.0 Hz, J2 = 2.4 Hz, 1H, CH-Glu), 4.25
(dd, J1 = 12.0 Hz, J2 = 4.6 Hz, 1H, CH-Glu), 4.37 (m, 1H,
CH-Glu), 4.48 (m, 1H, CH-Glu), 4.57 (dd, J1 = 8.8 Hz,
J2 = 3.6 Hz, 1H, CH-Glu), 4.60 (d, J = 8.0 Hz, 2H, CH2),
5.01–5.06 (m, 2H, CH2), 5.22 (m, 1H, CH-Glu), 6.83 (d,
Declarations
Conflict of interest There are no conficts of interest to declare.
1 3

Glucopyranoside‑Functionalized NHCs‑Pd(II)‑PEPPSI Complexes: Anomeric Isomerism…
hole-transporting material for perovskite solar cells. ACS Appl
References
Mater Interfaces 12(25):28246–28252
22. You G, Zhuang Q, Wang L, Lin X, Zou D, Lin Z, Zhen H,
Zhuang W, Ling Q (2020) Dopant-free, donor–acceptor-type
polymeric hole-transporting materials for the perovskite solar
cells with power conversion efciencies over 20%. Adv Energy
Mater 10(5):1903146
1. Zhao Q, Meng G, Nolan SP, Szostak M (2020) N-heterocyclic
carbene complexes in C–H activation reactions. Chem Rev
120(4):1981–2048
2. Sau SC, Hota PK, Mandal SK, Soleilhavoup M, Bertrand G (2020)
Stable abnormal N-heterocyclic carbenes and their applications.
Chem Soc Rev 49(4):1233–1252
23. Yin X, Guan L, Yu J, Zhao D, Wang C, Shrestha N, Han Y, An
Q, Zhou J, Zhou B, Yu Y, Grice CR, Awni RA, Zhang F, Wang
J, Ellingson RJ, Yan Y, Tang W (2017) One-step facile synthesis
of a simple carbazole-cored hole transport material for high-
performance perovskite solar cells. Nano Energy 40:163–169
24. Rakstys K, Saliba M, Gao P, Gratia P, Kamarauskas E, Paek
S, Jankauskas V, Nazeeruddin MK (2016) Highly efficient
perovskite solar cells employing an easily attainable bifuore-
nylidene-based hole-transporting material. Angew Chem Int Ed
55(26):7464–7468
3. Reshi NUD, Bera JK (2020) Recent advances in annellated NHCs
and their metal complexes. Coord Chem Rev 422:213334
4. Smith CA, Narouz MR, Lummis PA, Singh I, Nazemi A, Li C-H,
Crudden CM (2019) N-heterocyclic carbenes in materials chem-
istry. Chem Rev 119(8):4986–5056
5. Ji W, Wu H-H, Zhang J (2020) Axially chiral biaryl monophos-
phine oxides enabled by palladium/WJ-phos-catalyzed asymmet-
ric Suzuki-Miyaura cross-coupling. ACS Catal 10(2):1548–1554
6. Hong K, Sajjadi M, Suh JM, Zhang K, Nasrollahzadeh M, Jang
HW, Varma RS, Shokouhimehr M (2020) Palladium nanoparti-
cles on assorted nanostructured supports: applications for Suzuki,
heck, and sonogashira cross-coupling reactions. ACS Applied
Nano Materials 3(3):2070–2103
25. Nishimura H, Ishida N, Shimazaki A, Wakamiya A, Saeki
A, Scott LT, Murata Y (2015) Hole-hransporting materials
with a two-dimensionally expanded π-system around an azu-
lene core for efcient perovskite solar cells. J Am Chem Soc
137(50):15656–15659
7. Trzeciak AM, Augustyniak AW (2019) The role of palladium
nanoparticles in catalytic C–C cross-coupling reactions. Coord
Chem Rev 384:1–20
26. Zhong R, Lindhorst AC, Groche FJ, Kühn FE (2017) Immo-
bilization of N-heterocyclic carbene compounds: a synthetic
perspective. Chem Rev 117(3):1970–2058
8. Kantchev EAB, O’Brien CJ, Organ MG (2007) Palladium com-
plexes of N-heterocyclic carbenes as catalysts for cross-coupling
reactions—a synthetic chemist’s perspective. Angew Chem Int Ed
46(16):2768–2813
27. Crudden CM, Allen DP (2004) Stability and reactivity
of N-heterocyclic carbene complexes. Coord Chem Rev
248(21):2247–2273
28. Jacobsen H, Correa A, Poater A, Costabile C, Cavallo L (2009)
Understanding the M(NHC) (NHC=N-heterocyclic carbene)
bond. Coord Chem Rev 253(5):687–703
9. Beletskaya IP, Alonso F, Tyurin V (2019) The Suzuki-Miyaura
reaction after the Nobel prize. Coord Chem Rev 385:137–173
10. Zhang D, Wang Q (2015) Palladium catalyzed asymmetric
Suzuki-Miyaura coupling reactions to axially chiral biaryl com-
pounds: Chiral ligands and recent advances. Coord Chem Rev
286:1–16
29. Hazari N, Hruszkewycz DP (2016) Dinuclear PdI
com-
plexes with bridging allyl and related ligands. Chem Soc Rev
45(10):2871–2899
30. Correa A, Nolan SP, Cavallo L (2011) N-heterocyclic carbene
complexes of Au, Pd, and Pt as efective catalysts in organic syn-
thesis. Top Curr Chem 302:131–155
11. Suzuki A (2011) Cross-coupling reactions of organoboranes:
an easy way to construct C–C bonds. Angew Chem Int Ed
50(30):6722–6737
31. Poater A, Ragone F, Giudice S, Costabile C, Dorta R, Nolan SP,
Cavallo L (2008) Thermodynamics of N-heterocyclic carbene
dimerization: the balance of sterics and electronics. Organome-
tallics 27(12):2679–2681
12. Negishi E-I (2011) magical power of transition metals: past,
present, and future (Nobel Lecture). Angew Chem Int Ed
50(30):6738–6764
13. Heck RF (1968) Acylation, methylation, and carboxyalkylation
of olefns by Group VIII metal derivatives. J Am Chem Soc
90(20):5518–5526
32. Poater A, Cavallo L (2015) A comprehensive study of olefn
metathesis catalyzed by Ru-based catalysts. Beilstein J Org Chem
11:1767–1780
14. Sun B, Ning L, Zeng HC (2020) Confrmation of Suzuki-Miyaura
cross-coupling reaction mechanism through synthetic architecture
of nanocatalysts. J Am Chem Soc 142(32):13823–13832
15. Han B, Wang H, Wang C, Wu H, Zhou W, Chen B, Jiang J
(2019) Postsynthetic metalation of a robust hydrogen-bonded
organic framework for heterogeneous catalysis. J Am Chem Soc
141(22):8737–8740
33. Li G, Lei P, Szostak M, Casals-Cruañas E, Poater A, Cavallo
L, Nolan SP (2018) Mechanistic study of Suzuki-Miyaura cross-
coupling reactions of amides mediated by [Pd(NHC)(allyl)Cl]
precatalysts. ChemCatChem 10(14):3096–3106
34. Zhou T, Ma S, Nahra F, Obled AMC, Poater A, Cavallo L, Cazin
CSJ, Nolan SP, Szostak M (2020) [Pd(NHC)(mu-Cl)Cl]2: versa-
tile and highly reactive complexes for cross-coupling reactions
that avoid formation of inactive Pd(I) Of-cycle products. iScience
23(8):101377
16. R. F. Service (2013) Turning up the light. Science
342(6160):794–797
17. R. F. Service (2014) Perovskite solar cells keep on surging. Sci-
ence 344(6183):458–458
35. Shen D, Xu Y, Shi S-L (2019) A bulky chiral N-heterocyclic car-
bene palladium catalyst enables highly enantioselective Suzuki-
Miyaura cross-coupling reactions for the synthesis of biaryl atro-
pisomers. J Am Chem Soc 141(37):14938–14945
18. Bach U (2015) Perovskite solar cells: brighter pieces of the puzzle.
Nat Chem 7(8):616–617
19. Polman A, Knight M, Garnett EC, Ehrler B, Sinke WC (2016)
Photovoltaic materials: present efciencies and future challenges.
Science 352(6283):aad4424–aad4424
36. Diesel J, Grosheva D, Kodama S, Cramer N (2019) A bulky chiral
N-heterocyclic carbene nickel catalyst enables enantioselective
C–H functionalizations of indoles and pyrroles. Angew Chem Int
Ed 58(32):11044–11048
20. Zhang J, Sun Q, Chen QY, Wang YK, Zhou Y, Song B, Yuan NY,
Ding JN, Li YF (2019) High efciency planar p-i-n perovskite
solar cells using low-cost fuorene-based hole transporting mate-
rial. Adv Funct Mater 29(22):1900484
37. Rendon-Nava D, Alvarez-Hernandez A, Rheingold AL, Suarez-
Castillo OR, Mendoza-Espinosa D (2019) Hydroxyl-function-
alized triazolylidene-based PEPPSI complexes: metallacycle
formation efect on the Suzuki coupling reaction. Dalton Trans
48(10):3214–3222
21. Lee D, Sivakumar G, Manju, Misra R, Seok S II (2020)
Carbazole-based spiro fluorene-xanthene as an efficient
1 3

Z. Zhou et al.
57. Zhao W, Ferro V, Baker MV (2017) Carbohydrate–N-heterocyclic
carbene metal complexes: synthesis, catalysis and biological studies.
Coord Chem Rev 339:1–16
38. Zhang YY, Han FW, Zhang MY, Zhang HX, Li Y, Wang R, Zeng
YF, Liu GY (2020) Highly active Pd-PEPPSI complexes for Suzuki-
Miyaura cross-coupling of aryl chlorides: an investigation on the
efect of electronic properties. Chem Res Chinese U 36(5):859–864
39. Ouyang J-S, Li Y-F, Huang F-D, Lu D-D, Liu F-S (2018) The Highly
efcient Suzuki-Miyaura cross-coupling of (Hetero)aryl chlorides
and (Hetero)arylboronic acids catalyzed by “Bulky-yet-Flexible”
palladium-PEPPSI complexes in air. ChemCatChem 10(2):371–375
40. Aktas A, Celepci DB, Gok Y, Aygun M (2018) 2-Hydroxyethyl-
substituted Pd-PEPPSI complexes: synthesis, characterization and
the catalytic activity in the Suzuki-Miyaura reaction for aryl chlo-
rides in aqueous media. ChemistrySelect 3(35):9974–9980
41. Mika LT, Cséfalvay E, Németh Á (2018) Catalytic conversion of
carbohydrates to initial platform chemicals: chemistry and sustain-
ability. Chem Rev 118(2):505–613
58. Shi J-C, Zhou Z-G, Zheng S, Zhang Q, Jia L, Lin J (2014) Carbo-
hydrate-based phosphines as supporting ligand for palladium-cat-
alyzed Suzuki-Miyaura cross-coupling reaction. Tetrahedron Lett
55(18):2904–2907
59. Zhou Z, Zhao Y, Zhen H, Lin Z, Ling Q (2016) Poly(ethylene gly-
col)- and glucopyranoside-substituted N-heterocyclic carbene pre-
cursors for the synthesis of arylfuorene derivatives using efcient
palladium-catalyzed aqueous Suzuki reaction. Appl Organomet
Chem 30(11):924–931
60. Zhou Z-G, Yuan Y, Xie Y, Li M (2018) Green, efcient and reus-
able bis(imidazolium) ionic liquids promoted Pd-catalyzed aque-
ous Suzuki reaction for organic functional materials. Catal Lett
148(9):2696–2702
42. Kaur N, Singh A, Chopra HK (2018) Exploring low-cost natural pre-
cursors as chiral building blocks in synthesis: chiral carbohydrate-
ionic liquids. Mini-Rev Org Chem 15(3):208–219
61. Zhou Z-G, Li M, Liu GS, Xu GH, Xue J (2019) Ultra-small sugar-
substituted N-heterocyclic carbenes protected Pd nanoparticles and
catalytic activity. Appl Organomet Chem 33(7):e4942
43. Zhang X, Lin L, Huang H, Linhardt RJ (2020) Chemoenzymatic
synthesis of glycosaminoglycans. Acc Chem Res 53(2):335–346
44. Shi JC, Lei N, Tong QS, Peng YR, Wei JF, Jia L (2007) Synthe-
sis of chiral imidazolinium carbene from a carbohydrate and its
Rhodium(I) complex. Eur J Inorg Chem 2007(15):2221–2224
45. Tewes F, Schlecker A, Harms K, Glorius F (2007) Carbohydrate-
containing N-heterocyclic carbene complexes. J Organomet Chem
692(21):4593–4602
62. Zhou Zhonggao, Xie Qian, Zhou Xin, Yuan Yangyang, Pan Yan,
Dongliang Lu, Ziyi Du, Xue J (2020) Synthesis of glucoside-based
imidazolium salts for Pd-catalyzed cross-coupling reaction in water.
Carbohydr Res 496:108079
63. Salman AA, Tabandeh M, Heidelberg T, Hussen RSD, Ali HM
(2015) Alkyl-imidazolium glycosides: non-ionic—cationic hybrid
surfactants from renewable resources. Carbohydr Res 412:28–33
64. Amoroso F, Colussi S, Del Zotto A, Llorca J, Trovarelli A (2010)
An efcient and reusable catalyst based on Pd/CeO2 for the room
temperature aerobic Suzuki-Miyaura reaction in water/ethanol. J
Mol Catal A 315(2):197–204
46. Nishioka T, Shibata T, Kinoshita I (2007) Sugar-incorporated N-het-
erocyclic carbene complexes. Organometallics 26(5):1126–1128
47. Keitz BK, Grubbs RH (2010) Ruthenium olefn metathesis catalysts
bearing carbohydrate-based N-heterocyclic carbenes. Organometal-
lics 29(2):403–408
65. Imanaka Y, Hashimoto H, Kinoshita I, Nishioka T (2014) Incor-
poration of a sugar unit into a C-C–N pincer Pd complex using
click chemistry and Its dynamic behavior in solution and catalytic
ability toward the Suzuki-Miyaura coupling in water. Chem Lett
43(5):687–689
48. Yang CC, Lin PS, Liu FC, Lin IJB, Lee GH, Peng SM (2010) Glu-
copyranoside-incorporated N-heterocyclic carbene complexes of
silver(I) and palladium(II): efcient water-soluble Suzuki−Miyaura
coupling palladium(II) catalysts. Organometallics 29(22):5959–5971
49. Shibata T, Hashimoto H, Kinoshita I, Yano S, Nishioka T (2011)
Unprecedented diastereoselective generation of chiral-at-metal,
half sandwich Ir(III) and Rh(III) complexes via anomeric isomer-
ism on “sugar-coated” N-heterocyclic carbene ligands. Dalton Trans
40(18):4826–4829
66. Imanaka Y, Hashimoto H, Nishioka T (2015) Syntheses and cata-
lytic ability of sugar-incorporated N-heterocyclic carbene pincer Pd
complexes possessing various N-substituents. Bull Chem Soc Jpn
88:1135–1143
67. Imanaka Y, Shiomoto N, Tamaki M, Maeda Y, Nakajima H, Nish-
ioka T (2017) The arrangement of two N-heterocyclic carbene moi-
eties in palladium pincer complexes afects their catalytic activity
towards Suzuki-Miyaura cross-coupling reactions in water. Bull
Chem Soc Jpn 90(1):59–67
50. Shibata T, Ito S, Doe M, Tanaka R, Hashimoto H, Kinoshita I, Yano
S, Nishioka T (2011) Dynamic behaviour attributed to chiral car-
bohydrate substituents of N-heterocyclic carbene ligands in square
planar nickel complexes. Dalton Trans 40(25):6778–6784
51. Annunziata A, Amoresano A, Cucciolito ME, Esposito R, Ferraro
G, Iacobucci I, Imbimbo P, Lucignano R, Melchiorre M, Monti M,
Scognamiglio C, Tuzi A, Monti DM, Merlino A, Rufo F (2020)
Pt(II) versus Pt(IV) in carbene glycoconjugate antitumor agents:
minimal structural variations and great performance changes. Inorg
Chem 59(6):4002–4014
68. Imanaka Y, Nakao K, Maeda Y, Nishioka T (2017) Sugar-incor-
porated chelating bis-N-heterocyclic carbene palladium complexes.
Synthesis, structures, and catalytic ability for Suzuki-Miyaura cross-
coupling reactions in water. Bull Chem Soc Jpn 90(9):1050–1057
69. Xu B, Sheibani E, Liu P, Zhang J, Tian H, Vlachopoulos N,
Boschloo G, Kloo L, Hagfeldt A, Sun L (2014) Carbazole-based
hole-transport materials for efcient solid-state dye-sensitized solar
cells and perovskite solar cells. Adv Mater 26(38):6629–6634
70. Zhou Z-G, Zhao Y, Zhang C, Zhou D, Chen Y, Lin Z, Zhen H, Ling
Q (2017) A facile one-pot synthesis of hyper-branched carbazole
based polymer as hole-transporting material for perovskite solar
cells. J Mater Chem A 5:6613–6621
52. Cucciolito ME, Trinchillo M, Iannitti R, Palumbo R, Tesauro D, Tuzi
A, Rufo F, D’Amora A (2017) Sugar-incorporated N-heterocyclic-
carbene-containing gold(I) complexes: synthesis, characterization,
and cytotoxic evaluation. Eur J Inorg Chem 2017(42):4955–4961
53. Dieguez M, Pamies O, Ruiz A, Diaz Y, Castillon S, Claver C (2004)
Carbohydrate derivative ligands in asymmetric catalysis. Coord
Chem Rev 248(21–24):2165–2192
54. Dieguez M, Pamies O, Claver C (2004) Ligands derived from car-
bohydrates for asymmetric catalysis. Chem Rev 104(6):3189–3216
55. Dieguez M, Claver C, Pamies O (2007) Recent progress in asym-
metric catalysis using chiral carbohydrate-based ligands. Eur J Org
Chem 28:4621–4634
Publisher’s Note Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional afliations.
56. Woodward S, Diéguez M, Pàmies O (2010) Use of sugar-based
ligands in selective catalysis: recent developments. Coord Chem
Rev 254(17–18):2007–2030
1 3