Deoxygenative coupling of 2-aryl-ethanols catalyzed by unsymmetrical pyrazolyl-pyridinyl-triazole ruthenium

Article abstract of DOI:10.1016/j.mcat.2021.111391

A pyrazolyl-pyridinyl-triazole Ru complex was synthesized from unsymmetrical pyrazolyl-pyridinyl-triazole (PPT) skeleton ligand and characterized through X-ray crystallography. The corresponding heterogeneous pyrazolyl-pyridinyl-triazole Ru complexes on γ

Full text of DOI:10.1016/j.mcat.2021.111391

Molecular Catalysis 503 (2021) 111391
Contents lists available at ScienceDirect
Molecular Catalysis
journal homepage: www.journals.elsevier.com/molecular-catalysis
Deoxygenative coupling of 2-aryl-ethanols catalyzed by unsymmetrical
pyrazolyl-pyridinyl-triazole ruthenium
Fei Cao, Zheng-Chao Duan, Haiyan Zhu, Dawei Wang*
Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi, 214122, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
A pyrazolyl-pyridinyl-triazole Ru complex was synthesized from unsymmetrical pyrazolyl-pyridinyl-triazole
(PPT) skeleton ligand and characterized through X-ray crystallography. The corresponding heterogeneous
pyrazolyl-pyridinyl-triazole Ru complexes on γ-Al2O3 were characterized through SEM, TEM, XRD and XPS. Both
homogeneous and heterogeneous Ru catalysts revealed high activity for deoxygenative homocoupling of 2-
arylethanols.
Ruthenium complexes
Dual-deoxygenation
Heterogeneous catalysis
1. Introduction
excellent examples were developed, the efficient catalytic system for
deoxygenative coupling of 2-aryl-ethanols remains as a highly chal-
Alcohol is considered as an easily accessible, highly versatile,
abundant and renewable source to green chemistry, which therefore has
gained wide applications [1]. Deoxygenation of alcohols provides an
efficient and environmentally benign technique for producing biofuels
and platform chemicals by sustainable biomass-derived feedstocks.
Compared with borrowing hydrogen, dehydrogenation reactions [2,3],
deoxygenation, especially dual-deoxygenation process, is an ideal
means for synthesizing high energy-density hydrocarbons with
oxygen-rich biomass feedstocks and the simple alcohols as starting
materials. Among these processes, catalysts usually play a very impor-
tant role [4,5]. Up to now, only three examples on dual-deoxygenation
coupling of two alcohol-containing molecules were reported during the
past time. In 2011, Obora and Ishii reported an efficient, novel and atom
lenging, particularly recyclable catalysts [9].
Our interest in triazole-based ligands and the resulting catalysts was
initiated by studies of the catalytic applications in dehydrogenation and
borrowing hydrogen reactions [10]. However, the development of high
activity catalytic systems [11] has not achieved gratifying results: 1)
catalytic efficiency was not high; 2) most of the metals employed were
noble metals and catalysts usually could not be recovered; 3) these
catalysts couldn’t realize the deoxygenative coupling of 2-aryl-ethanols.
Herein, we reported the synthesis and characterizations of a new
pyrazolyl-pyridinyl-triazole ruthenium complex, which was confirmed
by
X-ray
crystallography.
Meanwhile,
the
heterogeneous
pyrazolyl-pyridinyl-triazole Ru on γ-Al2O3 was also synthesized and
characterized through SEM, TEM, XRD and XPS. Both homogeneous and
heterogeneous Ru catalysts displayed high catalytic activity for deoxy-
genative homocoupling of 2-arylethanols.
economical method about
α,ω-diarylalkanes from ω-arylalkanols
through sequential two-step pathways with [(Cp*IrCl2)2] and
a
[(Cp*IrCl2)2]/[{IrCl(cod)}2] /dppe (dppe: 1,2-bis(diphenylphosphino)
ethane) catalytic systems (Scheme 1) [6]. In 2018, Johnson and
co-workers developed Ru-catalyzed deoxygenative homocoupling of
2-arylethanols to produce 1,3-diarylpropenes through base-induced
decarbonylation in high yields with [RuCl2(PPh3)3]/(dppp) catalyst
(dppp:bis(1,3-diphenylphosphino-propane)) [7]. Liu and co-workers
reported the deoxygenative homo-coupling and cross-coupling reac-
tion of 2-arylethanols by a well-defined Mn/PNP pincer complex with
mechanism studies, the latter of which has not been achieved in previ-
ous works. This is also the first example of this transformation being
achieved via a non-noble metal catalysis (Scheme 1) [8]. Although three
2. Experimental
2.1. The synthesis of pyrazolyl-pyridinyl-triazole Ru
Firstly, ligand pyrazolyl-pyridinyl-triazole (L1) was prepared ac-
cording to synthetic methods of similar ligand compounds [12]. The
designed Ru complex (pyrazolyl-pyridinyl-triazole Ru: PPT-Ru) was
successfully synthesized in 60 % by mixing RuCl2(PPh3)3 and ligand L1
in 1:1 M ratio in toluene at 110 ◦C under N2 atmosphere for 24 h. The
exact structure of ruthenium complex (PPT-Ru) was confirmed by
* Corresponding author.
E-mail address: wangdw@jiangnan.edu.cn (D. Wang).
https://doi.org/10.1016/j.mcat.2021.111391
Received 1 November 2020; Received in revised form 31 December 2020; Accepted 2 January 2021
Available online 29 January 2021
2468-8231/© 2021 Elsevier B.V. All rights reserved.

F. Cao et al.
Molecular Catalysis 503 (2021) 111391
activity in deoxygenative coupling of 2-arylethanols was examined.
Preliminary results showed that the reaction could proceed smoothly
and the desired product was successfully isolated in moderate yield.
After a series of reaction conditions screening (Table 1), toluene and
potassium tert-butoxide were proven to be the most efficient solvent and
base, respectively.
As shown in Table 2, a wide range of substrates with functional
groups or substituents including methyl, methoxy, chloro, bromine, and
heterocycle at different positions of phenyl ring were tolerated, afford-
ing target products from moderate to good yields.
A sulfur-containing substrate was employed to this reaction and
afforded deoxygenative coupling product 3o in 75 % yield, indicating
that thiophene group reacted well under the best reaction conditions.
Dihalogen substituted substance was also compatible in 62 % yield.
Increased steric bulk on the aryl group impeded the reaction. For
instance, 1-naphthylethanol 2p reacted to produce propene derivative
3p in 50 % yield. All chloride, bromide- and fluorine- substituted aryl
ethanols in ortho-, meta- or para-positions could be successfully con-
verted into the corresponding diarylpropene derivatives with high
yields. From the substrate experiments, it is obvious that the electronic
effect affects the yield greatly. In brief, the substrate with an electron-
donating group could enhance the reaction rate compared with an
electron withdrawing group.
Scheme 1. Catalytic deoxygenative coupling of alcohols.
single-crystal X-ray diffraction (Scheme 2) [13].
2.2. General procedure for synthesis of PPT-Ru
Under N2 atmosphere,
a mixture of RuCl2(PPh3)3 (191 mg,
0.2 mmol) and 1 (52 mg, 0.2 mmol) in toluene (15 mL) was refluxed for
24 h. The mixture was cooled to ambient temperature to precipitate a
red-brown microcrystalline solid. The solid was filtered off, washed with
diethyl ether (3 × 15 mL) and dried under vacuum to afford the desired
product PPT-Ru [13].
2.3. General procedure for deoxygenative homocoupling of the 2-aryl-
ethanols
3.2. The synthesis of PPT-Ru@Al2O3
Considering green chemistry and energy economy point, if catalyst
PPT-Ru could be recovered, it would be much betterfor this trans-
formation. Gushikem and co-workers developed metal ion and nitrogen-
containing organosilane bonded on Al2O3/Cellulose acetate hybrid
material surface in 2002 [14]. Since cellulose acetate/Al2O3 hybrid
material can be further chemically modified by reacting with (RO)3Si
(CH2)3L-type alkoxysilane reagents (L = amine groups). The resulting
chemically modified hybrid materials have been used to adsorb metal
ions. The metal ions binding to the nitrogen atoms and the anions can be
in the inner coordination sphere, and be bound to the metal ion, or still
in the outer sphere to balance the charge [15]. In any cases, the equi-
librium of the immobilized complex formation with the electrically
neutral grafted ligands can formally be expressed as:
Under N2 atmosphere, ethanol derivatives (1.0 mmol), PPT-Ru
catalyst (0.1 mol%) and KOtBu (0.5 equiv.) were introduced in a
Schlenk tube (25 mL), successively. The tube was evacuated and refilled
with high purity nitrogen for three times. Then the Schlenk tube was
closed and the resulting mixture was stirred at 120 ◦C for 24 h under
toluene (2.0 mL) conditions. After cooling down to room temperature,
water was added to quench the reaction and extracted with ethyl ace-
tate, the organic phase was concentrated by removing the solvent under
vacuum. Finally, the residue was purified by column chromatography
with petroleum ether as eluent to give the desired product.
2.4. General procedure for heterogeneous catalyst experiment
Therefore, we designed the synthesis of the heterogeneous Ru cata-
lyst according to Gushikem theory (Fig. 1). However, alumina has no
coordination sites. Therefore, we chemically modified alumina to have
coordination sites on its surface, and then coordinated with metal ion.
Alumina has stable mechanical properties, toughness and chemical
Under N2 atmosphere, ethanol derivatives (1.0 mmol), PPT-
Ru@Al2O3 catalyst (0.1 mol%, 2 % loading, w/w) and KOtBu (0.5
equiv.) were introduced in a Schlenk tube (25 mL), successively. The
tube was evacuated and refilled with high purity nitrogen for three
times. Then the Schlenk tube was closed and the resulting mixture was
stirred at 120 ◦C for 24 h under toluene (2.0 mL) conditions. After
cooling down to room temperature, water was added to quench the
reaction, then filter to obtain mother liquor and extracted with ethyl
acetate, the organic phase was concentrated by removing the solvent
under vacuum. Finally, the residue was purified by column chroma-
tography with petroleum ether as eluent to give the desired product.
Table 1
The reaction conditions screeninga,b
.
entry
catalyst
additive
solvent
yield [%]b
1
–
K2CO3
–
toluene
toluene
toluene
toluene
toluene
toluene
toluene
dioxane
H2O
<5
<5
74
3. Results and discussion
2
PPT-Ru
PPT-Ru
PPT-Ru
PPT-Ru
PPT-Ru
PPT-Ru
PPT-Ru
PPT-Ru
PPT-Ru
PPT-Ru
–
3
K2CO3
KOH
3.1. Catalytic activity of catalyst PPT-Ru
4
69
5
NaOH
Cs2CO3
KOtBu
KOtBu
KOtBu
KOtBu
KOtBu
KOtBu
52
6
<5
89
With this ruthenium (II) complex (PPT-Ru) in hand, the catalytic
7
8
76
9
<5
<5
<5
NRc
10
11
12
THF
MeOH
toluene
a
Conditions: 2a (1 mmol), catalyst (0.1 mol%), additive (0.5 mmol), solvent
(2.0 mL), 120 ◦C or reflux, 24 h.
b
c
Isolated yields.
Scheme 2. The synthesis of pyrazolyl-pyridinyl-triazole Ru.
No reaction, see: Ref [7].
2

F. Cao et al.
Molecular Catalysis 503 (2021) 111391
Table 2
Ru-catalyzed deoxygenative homocoupling of the 2-aryl-ethanolsa,b
.
a
Conditions: 2 (1.0 mmol), PPT-Ru (0.1 mol%), KOtBu (0.5 eq.), toluene
(2.0 mL), N2, 120 ◦C, 24 h.
b
Isolated yields.
Fig. 2. EDX images of PPT-Ru@Al2O3.
Fig. 1. Possible loading mechanism of PPT-Ru@Al2O3.
inertness, strong volume effect, quantum size effect and surface effect
[16]. Therefore, it can fully interact with the core components of the
catalyst, improve the catalytic efficiency. Al2O3 has a variety of different
crystals, and its derivatives can be converted at different temperatures.
γ-Al2O3 has a large specific surface area and porosity, high activity, good
adsorption performance and good acid-base thermal stability.
Firstly, γ-Al2O3 was washed with water and ethanol three times,
respectively. Then γ-Al2O3 was added into toluene. The alumina was
modified with modifier (APTES, 3-aminopropyltriethoxysilane) in
toluene for 24 h. The mixture was cooled to ambient temperature by
centrifugation to obtain the solid, followed by washing with ethanol
three times. Next, modified γ-Al2O3, PPT-Ru complex in mixed solvent
ethanol and toluene was stirred for 24 h at 100 ◦C. After filtration, the
target product was obtained as a red solid. Finally, after ultrasonic
washing and drying, the desired solid PPT-Ru@Al2O3 was attained (2 %
loading, w/w) (For detailed preparation process, please see supporting
information).
Fig. 3. (a) SEM image of γ-Al2O3, (b) SEM image of PPT-Ru@Al2O3, (c) TEM
image of γ-Al2O3, (d) TEM image of PPT-Ru@Al2O3.
clearly seen the metal thread, characteristic structure and unit cell size
of PPT-Ru@Al2O3 in the (d).
X-ray power diffraction (XRD) was conducted to verify structure
(Fig. 4). The alumina had a characteristic absorption peak at 2θ = 37.4◦,
39.42◦, 45.92◦ and 66.64◦. Corresponding to the characteristic peak of
aluminum at (311) (222) (400) (440), which was reported in previous
3.3. Characterization of PPT-Ru@Al2O3
After the synthesis, PPT-Ru@Al2O3 was fully characterized by en-
ergy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction
(XRD), scanning electron microscopy (SEM), transmission electron mi-
croscopy (TEM), and X-ray photo-electronic spectroscopy (XPS).
Energy dispersive X-ray spectroscopy (EDX) of PPT-Ru@Al2O3
(Fig. 2) introduced the existence of the expected elements (C, O, N, Al,
Si) in the structure. Other elements appeared after loading such as P, Cl
and Ru atoms. In order to observe the phenomenon more clearly, we
enlarged the region of peaks in the 2–3 (KeV). This explained that these
atoms came from PPT-Ru@Al2O3, which indicated that metal complex
had successfully loaded on the carrier.
The images of (a) and (b) were scanning electron micro-scope of
γ-Al2O3 and PPT-Ru@Al2O3 (Fig. 3). It could be seen that the
morphology of γ-Al2O3 was blocky from the figure a, which was bene-
ficial to load for metal complex. In the Fig. 3(b), the surface of alumina
had changed after the metal complex was loaded. It showed foamy
feature on the surface of γ-Al2O3. The image of (c) and (d) was trans-
mission electron microscopy of γ-Al2O3 and PPT-Ru@Al2O3. It could be
Fig. 4. XRD pattern of γ-Al2O3 and PPT-Ru@Al2O3.
3

F. Cao et al.
Molecular Catalysis 503 (2021) 111391
studies. Meanwhile the peak at 2θ = 17.9◦ of XRD pattern was peak of
ruthenium. The result revealed that PPT-Ru was well loaded on the
γ-Al2O3.
Finally, the surface elemental chemical states and contents of PPT-
Ru@Al2O3 catalyst were revealed by XPS. As shown in Fig. 5, the
characteristic peaks of O 1s, C 1s, N 1s, Al 2p, P 2p and Ru 3p appeared
in the sample at ~531.3 eV, ~284.9 eV, ~400.4 eV, ~74.3 eV, ~138.2
eV, ~462.2 eV, respectively, which was consistent with the chemical
composition of the sample. Therefore, all the characterization results
disclosed that PPT-Ru was successfully supported on supporter γ-Al2O3.
3.4. Catalytic activity of catalyst PPT-Ru@Al2O3
With this heterogeneous ruthenium(II) complex (PPT-Ru@Al2O3) in
hand, the catalytic activities in deoxygenative coupling of 2-aryletha-
nols were subsequently examined.
Fig. 5. XPS spectra of PPT-Ru@Al2O3.
The experiments indicated that heterogeneous catalyst PPT-
Ru@Al2O3 was employed, and it was found that the reaction can achieve
a good conversion rate under the same conditions (Table 3). Although
the yields were different in the same deoxygenative homocoupling of 2-
arylethanols reaction under homogeneous and heterogeneous catalysts,
the difference was not large. It was observed that the inorganic material
carrier did not affect the smooth progress of the reaction. The different
yields of this transformation might be caused by the uneven dispersion
of the metal catalyst on the surface of the carrier.
Table 3
PPT-Ru@Al2O3-catalyzed deoxygenative homocoupling of the 2-aryl-ethanolsa,
b
.
3.5. Mechanism exploration
The success of this homogeneous PPT-Ru catalytic system on this
deoxygenative coupling reaction promoted us to better gain insights into
the possible mechanism. Based on the previous studies [6–8] and this
Ru-catalyzed deoxygenative homocoupling of 2-arylethanols, a possible
mechanism was proposed to better understand this transformation.
Firstly, the substrate was dehydrogenated under ruthenium catalyst to
obtain A (Scheme 3). Subsequently, the reaction occurred by base to
generate the β-hydroxyaldehyde B. Then β-hydroxyaldehyde dehy-
drated to form an 1,3-diphenylpropene derivatives C through aldol
condensation. The intermediate E further underwent deformylation by
nucleophilic attack on the carbonyl group and by hydroxide to afford the
allyl anionic species F, which was protonated to deliver the final product
3.
a
Conditions: 2 (1.0 mmol), PPT-Ru@Al2O3 (0.1 mol%, 2% loading, w/w),
KOtBu (0.5 equiv.), toluene (2.0 mL), 120 ◦C, 24 h.
b
Isolated yields.
3.6. Reusability of the catalyst
Subsequently, we recovered the catalyst and repeated experiments
with phenylethanol as a substrate. The composite PPT-Ru@Al2O3 was
washed and centrifuged several times with water and ethanol, and dried
for reuse in the borrowing hydrogen reaction (Scheme 4). As the recy-
cling time increase, the yield gradually decreased.
Scheme 3. The proposed reaction mechanism.
Finally, a gram scale synthesis of alkenes was attempted to illustrate
the practicality of this PPT-Ru catalytic system. It was disclosed that
more than 6.0 g of (E)-4,4’-(prop-1-ene-1,3-diyl)bis(bromobenzene)
(3d) could be isolated in 75 % yield, which further revealed that PPT-Ru
catalyst has good catalytic performance (Scheme 5).
4. Conclusions
Scheme 4. Recycled experiments.
In summary, we developed a new kind of heterogeneous ruthenium
catalyst which was synthesized from pyrazolyl-pyridinyl-triazole
through coordination bonds. The supported catalyst was fully charac-
terized and used in a variety of tests. This type of ruthenium catalyst was
proven to be effective for heterogeneous Ru-catalyzed deoxygenative
coupling of 2-arylethanols.
Declaration of Competing Interest
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influence
4

F. Cao et al.
Molecular Catalysis 503 (2021) 111391
(2016) 784;
(i) H. Hikawa, R. Ichinose, S. Kikkawa, I. Azumaya, Green Chem. 20 (2018) 1297.
[4] (a) B. Xiong, S.-D. Zhang, L. Chen, B. Li, H.-F. Jiang, M. Zhang, Chem. Commun.
52 (2016) 10636;
(b) Z. Tan, H. Jiang, M. Zhang, Chem. Commun. 52 (2016) 9359;
(c) F. Xie, R. Xie, J.-X. Zhang, H.-F. Jiang, L. Du, M. Zhang, ACS Catal. 7 (2017)
4780;
Scheme 5. The synthesis of (E)-4,4’-(prop-1-ene-1,3-diyl) bis (bromobenzene)
in a large scale.
(d) H.-J. Pan, T.W. Ng, Y. Zhao, Chem. Commun. 51 (2015) 11907;
(e) Z.-Q. Rong, Y. Zhang, R.H.B. Chua, H.-J. Pan, Y. Zhao, J. Am. Chem. Soc. 137
(2015) 4944;
the work reported in this paper.
(f) Y. Zhang, C.-S. Lim, D.S.B. Sim, H.-J. Pan, Y. Zhao, Angew. Chem. Int. Ed. 53
(2014) 1399;
CRediT authorship contribution statement
(g) C.S. Lim, T.T. Quach, Y. Zhao, Angew. Chem. Int. Ed. 56 (2017) 7176;
(h) X. Chen, H. Zhao, C. Chen, H. Jiang, M. Zhang, Angew. Chem. Int. Ed. 56
(2017) 14232;
Fei Cao: Data curation, Formal analysis, Investigation, Methodology,
Writing - original draft. Zheng-Chao Duan: Conceptualization, Data
curation. Haiyan Zhu: Resources, Software, Formal analysis. Dawei
Wang: Writing - review & editing, Project administration, Funding
acquisition.
(i) F. Li, L. Lu, P. Liu, Org. Lett. 18 (2016) 2580;
(j) R. Wang, H. Fan, W. Zhao, F. Li, Org. Lett. 18 (2016) 3558;
(k) S. Li, X. Li, Q. Li, Q. Yuan, X. Shi, Q. Xu, Green Chem. 17 (2015) 3260;
(l) Q. Xu, J. Chen, H. Tian, X. Yuan, S. Li, C. Zhou, J. Liu, Angew. Chem. Int. Ed. 53
(2014) 225;
(m) X. Cui, X. Dai, Y. Deng, F. Shi, Chem. Eur. J. 19 (2013) 3665;
(n) T. Liu, L. Wang, K. Wu, Z. Yu, ACS Catal. 8 (2018) 7201.
[5] (a) B. Gnanaprakasam, J. Zhang, D. Milstein, Angew. Chem. Int. Ed. 49 (2010)
1468;
Acknowledgements
(b) Y. Zhao, S.W. Foo, S. Saito, Angew. Chem. Int. Ed. 50 (2011) 3006;
(c) S. Gowrisankar, H. Neumann, M. Beller, Angew. Chem. Int. Ed. 50 (2011)
5139;
We gratefully acknowledge financial support of this work by the
National Natural Science Foundation of China (21776111, 21861039),
the Fundamental Research Funds for the Central Universities (JUSRP
51627B) and MOE & SAFEA for the 111 Project (B13025).
¨
(d) L. Neubert, D. Michalik, S. Bahn, S. Imm, H. Neumann, J. Atzrodt, V. Derdau,
W. Holla, M. Beller, J. Am. Chem. Soc. 134 (2012) 12239;
(e) T. Yan, B.L.T. Feringa, K. Barta, Nat. Commun. 5 (2014) 5602;
(f) T. Yan, B.L. Feringa, K. Barta, ACS Catal. 6 (2016) 381;
(g) P. Hu, Y. Ben-David, D. Milstein, Angew. Chem. Int. Ed. 55 (2016) 1061;
(h) N. Deibl, R. Kempe, J. Am. Chem. Soc. 138 (2016) 10786.
[6] Y. Obora, Y. Anno, R. Okamoto, T. Matsuura, Y. Ishii, Angew. Chem. Int. Ed. 50
(2011) 8618.
Appendix A. Supplementary data
Supplementary material related to this article can be found, in the
online version, at doi:https://doi.org/10.1016/j.mcat.2021.111391.
[7] S. Manojveer, S.J.K. Forrest, M.T. Johnson, Chem. Eur. J. 24 (2018) 803.
[8] Y. Wang, Z. Shao, K. Zhang, Q. Liu, Angew. Chem. Int. Ed. 57 (2018) 15143.
´
[9] (a) R. Cano, M. Yus, D.J. Ramon, Chem. Commun. 48 (2012) 7628;
(b) M.G. Mura, L.D. Luca, M. Taddei, J.M.J. Williams, A. Porcheddu, Org. Lett. 16
(2014) 2586;
References
(c) S. Manojveer, S. Salahi, O.F. Wendt, M.T. Johnson, J. Org. Chem. 83 (2018)
10864.
[1] (a) Recent reviews: L. Alig, M. Fritz, S. Schneider Chem. Rev. 119 (2019) 2681;
(b) D. Wei, C. Darcel, Chem. Rev. 119 (2019) 2550;
(c) T. Irrgang, R. Kempe, Chem. Rev. 119 (2019) 2524;
(d) A. Corma, J. Navas, M.J. Sabater, Chem. Rev. 118 (2018) 1410;
(e) A. Mukherjee, D. Milstein, ACS Catal. 8 (2018) 11435;
(f) G. Chelucci, Coord. Chem. Rev. 331 (2017) 1;
[10] (a) Q. Yang, Y. Zhang, W. Zeng, Z.-C. Duan, X. Sang, D. Wang, Green Chem. 21
(2019) 5683;
(b) X. Sang, X. Hu, R. Tao, Y. Zhang, H. Zhu, D. Wang, ChemPlusChem 85 (2020)
123.
[11] (a) W. Yao, Z.-C. Duan, Y. Zhang, X. Sang, X.-F. Xia, D. Wang, Adv. Synth. Catal.
361 (2019) 5695;
(g) F. Huang, Z. Liu, Z. Yu, Angew. Chem. Int. Ed. 55 (2016) 862;
(h) Q. Yang, Q. Wang, Z. Yu, Chem. Soc. Rev. 44 (2015) 2305;
(i) A. Nandakumar, S.P. Midya, V.G. Landge, E. Balaraman, Angew. Chem. Int. Ed
54 (2015) 11022;
(b) D. Ye, R. Huang, H. Zhu, L.-H. Zou, D. Wang, Org. Chem. Front. 6 (2019) 62;
(c) Q. Yang, Y. Zhang, W. Zeng, Z.-C. Duan, X. Sang, D. Wang, Green Chem. 21
(2019) 5683;
(d) Z. Xu, D.-S. Wang, X. Yu, Y. Yang, D. Wang, Adv. Synth. Catal. 359 (2017)
3332;
(j) B. Chen, L. Wang, S. Gao, ACS Catal. 5 (2015) 5851;
(k) K.-I. Shimizu, Catal. Sci. Technol. 5 (2015) 1412.
[2] (a) A.J.A. Watson, J.M.J. Williams, Science 329 (2010) 635;
(b) C. Gunanathan, D. Milstein, Science 341 (2013) 249;
(c) P. Hu, Y. Ben-David, D. Milstein, Angew. Chem. Int. Ed. 55 (2016) 1061;
(d) P. Daw, S. Chakraborty, J.A. Garg, Y. Ben-David, D. Milstein, Angew. Chem.
Int. Ed. 55 (2016), 14373;
(e) Y. Qiu, Y. Zhang, L. Jin, L. Pan, G. Du, D. Ye, D. Wang, Org. Chem. Front. 6
(2019) 3420.
[12] L. Wang, N. Liu, B. Dai, H. Hu, Eur. J. Org. Chem. 29 (2014) 6493.
[13] CCDC-1944328 (PPT-Ru) Contains the Supplementary Crystal-lographic Data for
This Paper. These Data Can be Obtained Free of Charge from the Cambridge
Crystallo-graphic Data Centre, 2021. viawww.ccdc.cam.ac.uk/data_re-quest/cif.
[14] A.M. Lazarin, R. Landers, Y.V. Kholin, Y. Gushikem, J. Colloid Interface Sci. 254
(2002) 31.
(e) S. Gowrisankar, H. Neumann, M. Beller, Angew. Chem. Int. Ed. 50 (2011)
5139;
(f) M. Zhang, X. Fang, H. Neumann, M. Beller, J. Am. Chem. Soc. 135 (2013)
11384.
´
[15] (a) C. Pozo, A. Corma, M. Iglesias, F. Sanchez, Organometallics 29 (2010) 4491;
(b) Y. Gushikem, Y. Ohmori, J. Biotechnol. 33 (1994) 205;
(c) Q. Zhang, H. Wang, W. Hu, X. Xu, Z. Xu, C. Chen, D. Wang, J. Chem, Technol.
Biotechnol. 95 (2020) 2027;
[3] (a) F.G. Mutti, T. Knaus, N.S. Scrutton, M. Breuer, N.J. Turner, Science 349 (2015)
1525;
(b) N. Deibl, R. Kempe, J. Am. Chem. Soc. 138 (2016) 10786;
(c) T. Yan, B.L. Feringa, K. Barta, ACS Catal. 6 (2016) 381;
(d) C. Schlepphorst, B. Maji, F. Glorius, ACS Catal. 6 (2016) 4184;
(e) D. Shen, D.L. Poole, C.C. Shotton, A.F. Kornahrens, M.P. Healy, T.J. Donohoe,
Angew. Chem. Int. Ed. 54 (2015) 1642;
(d) W. Yao, Y. Zhang, H. Zhu, C. Ge, D. Wang, Chin. Chem. Lett. 31 (2020) 701;
(e) A.M. Lazarin, Y. Gushikem, J. Braz. Chem. Soc. 13 (2002) 8;
(f) V.N. Zaitsev, Y.V. Kholin, E.Y. Gorlova, I.V. Khristenko, Anal. Chim. Acta 379
(1999) 11;
(g) Y. Kholin, S. Myerniy, G. Varshal, Adsorp. Sci. Technol. 18 (2000) 267.
[16] L. Huang, F. Qin, Z. Huang, Y. Zhuang, J. Ma, H. Xu, W. Shen, ChemCatChem 10
(2018) 381.
(f) T.T. Dang, B. Ramalingam, A.M. Seayad, ACS Catal. 5 (2015) 4082;
(g) X. Xie, H.V. Huynh, ACS Catal. 5 (2015) 4143;
(h) H. Hikawa, T. Koike, K. Izumi, S. Kikkawa, I. Azumaya, Adv. Synth. Catal. 358
5