Transfer hydrogenation of alkynes into alkenes by ammonia borane over Pd-MOF catalysts

Article abstract of DOI:10.1039/d0dt00472c

Ammonia borane with both hydridic and protic hydrogens in its structure acted as an efficient transfer hydrogenation agent for selective transformation of alkynes into alkenes in non-protic solvents. Catalytic synergy between the μ₃-OH groups of the UiO-66(Hf) MOF and Pd active sites in Pd/UiO-66(Hf) furnished an elusive >98% styrene selectivity and full phenylacetylene conversion at room temperature. Such performance is not achievable by a Pd + UiO-66(Hf) physical mixture or by a commercial Pd/C catalyst.

Full text of DOI:10.1039/d0dt00472c

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Transfer Hydrogenation of Alkynes into Alkenes by Ammonia
Borane over Pd-MOF Catalyst
Vasudeva Rao Bakuru,a, b Debabrata Samanta,c, d Tapas Kumar Maji,c and Suresh Babu Kalidindi. *a, e
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Ammonia borane with both hydridic and protic hydrogens in its
strcture acted as effcient transfer hydrogenation agent for
selective transformation of alkynes into alkenes in non-protic
solvents. Catalytic synergy between μ3-OH groups of UiO-66(Hf)
MOF and Pd active sites in Pd/UiO-66(Hf) furnished elusive >98%
of styrene selectivity and full phenylacetylene conversion at room
temperature. Such performance is not accessible by Pd+UiO-
66(Hf) physical mixture or by commercial Pd/C catalyst.
Selective conversion of alkynes into alkenes by avoiding
over-hydrogenation has received considerable attention
because of its industrial importance.1 Very few catalytic
studies that deals with high selectivity towards
semihydrogenation products have been reported using
hazardous pressurized H2 as hydrogen source.2 In recent times,
transfer hydrogenation has emerged as a safer and viable
alternative to replace hazardous pressurized H2 gas in
hydrogenation reactions.3 Transfer hydrogenation involves the
addition of hydrogen to a molecule from a source other than
gaseous H2. A range of hydrogen transfer reagents such as
isopropanol,4 formic acid,5 hydrazine,6 benzothiazoles,7 sodium
Scheme 1: Transfer hydrogenation of phenylacetylene under uncatalyzed
and catalyzed conditions using ammonia borane as a hydrogen source.
an interesting Lewis acid-base adduct that contains both
hydridic and protic hydrogens in its structure. It is a quite
stable compound and safer to handle at ambient conditions.
Because of the presence of 19.6 wt % of hydrogen content, the
compound has received substantial attention as a solid state
hydrogen storage medium.12 AB is found to participate in
double H transfer reactions with activated double bonds(C=N,
activated C=C, C=O) through six membered transition state
that enables control over stereo- and chemo- selectivity.10
Transfer hydrogenation of alkynes with AB has been
studied using homogeneous catalysts.13 However, only very
few heterogeneous catalysts namely, Au/TiO2, Pt/TiO2, Cu2O,
and Ni nanoparticles have been reported for this reaction. 14 In
these four studies, transfer hydrogenation has been carried
out in protic solvents (water/alcohols). It is noteworthy that,
unlike in protic solvents, AB dehydrogenation in non-protic
9
borohydride8 and triethylsilane have been employed with a
better chemo- and stereo-selectivities.
Recently, ammonia borane (H3N·BH3, AB) has emerged as
an interesting transfer hydrogenation agent because of its
ability to participate in double H transfer reactions.10, 11 AB is
a. Address here. M. Sc. V. R. Bakuru, Dr. S. B. Kalidindi, Materials Science Division,
Poornaprajna Institute of Scientific
562164, India.
Research, Devanahalli, Bangalore Rural-
b. V. R. Bakuru ,Graduate studies, Manipal Academy of Higher Education,Manipal,
576 104, India
c. Dr. D. Samanta, Prof. Dr. T. K. Maji, Chemistry and Physics of Materials Unit, solvent lends a possibility for regeneration of the starting
School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced
material from the spent BNHX products.15, 16 In view of this, we
Scientific Research (JNCASR), Jakkur, Bangalore-560064, India.
d.Present address: Department of Chemistry, Indian Institute of Technology,
Kanpur-208016
explored transfer hydrogenation in a non- aqueous medium
with AB under both non-catalytic/catalytic
conditions(Scheme1).
e. Present address: Department of inorganic and analytical chemistry, Andhra
university,Visakhapatnam,India-530003, E-mail: ksureshu@gmail.com.
Metal-organic frameworks (MOFs) with well defined
porosity and exceptional surface areas have attrracted much
attention as a new class of tunable hetrogenaous catalysts.17
To facilitate transfer hydrogenation with AB, we supported Pd
† Footnotes relating to the title and/or authors should appear here.
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
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nanoparticles onto UiO-66(Hf) {Hf6O4 (OH)4[(O2C)-C6H4-(CO2)]6}
MOF with a objective of bringing μ3-OH groups and Pd sites in
close proximity. As AB is known for its hydrogen bonding
ability such arrangment of active sites can have pronounced
effect on transfer hydrogenation.
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DOI: 10.1039/D0DT00472C
Table 1. Transfer hydrogenation of phenylacetylene using different hydrogen sources.
S.No
Source
EtOH
Isopropanol
HCOOH
H2
Phenylacetylene conv.(%)
Styrene sel.(%)
1
2
3
4
5
6
7
0.0
0.0
0.0
0.0
4.5
7.5
99.9
-
-
-
-
NaBH4
99.9
99.9
99.9
N2H4 H2O
͘
NH3BH3
[a] Reaction conditions: 0.50 mmol of hydrogen source, 1 mL of 1, 4-
dioxane and 0.25 mmol of PA at 110 ˚C for 1h.
Initially, we have screened various transfer hydrogenation
agents (Table1) for semi hydrogenation of phenylacetylene
(PA) in catalyst free conditions at 110 ˚C in a non-aqueous
solvent (1, 4- dioxane). The reactions were carried out in a
closed system. As evident from Table 1, traditional transfer
agents isopropanol, ethanol, and formic acid did not show any
PA conversions and inferior PA conversions have been
observed with NaBH4 and N2H4·H2O. With AB as a hydrogen
source, full conversion of PA has been realized with a
remarkable >99 % ST selectivity (Figure S3, Figure S4). It could
be noted that achieving higher ST selectivity (>95 %) at full PA
Figure 1. Transfer hydrogenation of phenylacetylene (PA) using ammonia
borane (AB) in the absence of catalyst in non-aqueous medium a) at different
reaction temperatures for 1h, b) different PA/AB molar ratios at 110 ˚C for 1h,
and c) Time resolved study at 110 ˚C. Reaction conditions: 0.50 mmol of AB, 1
mL of 1, 4-dioxane and 0.25 mmol of PA.
conversions is
a challenge in case of metal-catalyzed
hydrogenation reactions (with H2).18 Further, ST was subjected
to transfer hydrogenation directly under same reaction
conditions as PA. We did not observe formation of any ethyl
benzene in this reaction. This suggests that AB selectively
transfers hydrogen to C≡C bond over C═C under our reaction
conditions. Further, when reactions were carried out in protic
solvents (Section S5, Figure S2) such as water and ethanol, the
PA conversion were only 0% and 7.0%, respectively. This
justifies use of non-protic solvents for uncatalyzed transfer
hydrogenation.
As evident from Figure 1a, 110 °C is found to be the
optimized temperature. Temperatures like 100-110 °C are very
close to dehydrogenation temperatures of neat AB. Therefore,
at these temperatures, there will be two competitive
processes, one transfer hydrogenation reaction and other self
dehydrogenation of AB itself. As a result, excess AB (PA: AB =2)
was needed to realize full PA conversions (Figure 1b). The
reaction proceeded to completion in about 15 min (Figure 1c).
The ST selectivity remained high (>99 %) at all conversions.
Prolongation of reaction time did not change the ST selectivity.
Figure 2. M06-2X/cc-pVTZ (PCM, 1, 4-dioxane) calculated structures and free
energies (kcalmol-1) for the reduction of phenylacetylene with NH3BH3.
Distances on transition state structures are shown in picometer (pm) unit.
21
asynchronous double-H-transfer process from AB to PA
Depending upon the relative orientation of AB and PA, two
possible six-membered cyclic transition states, TS1 and TS2
were located with free energy barriers of 32.6 kcal mol-1 and
33.4 kcal mol-1, respectively (Figure 2). The TS1 and TS2
represent B−H•••C/N−H•••C* and B−H•••C*/N−H•••C
hydrogen transfer, respectively (C* = acetylenic CH). The
barriers are indicative for very slow reaction kinetics, thus
required 110 ˚C to accelerate the reaction. The reaction is
thermodynamically favorable by 43.6 kcal mol-1. Several
So, in contrast to metal-catalyzed hydrogenation reactions,18
a
strict control over the reaction time is not necessary to
maintain high ST selectivity. As expected, molecular H2 did not
react with PA (in the absence of a catalyst) under our reaction
19
conditions.
To obtain mechanistic insight of the reaction, density
functional theoretical (DFT) calculations were performed at
20
M06-2X/cc-pVTZ level
(Figure 2) which revealed an
2 | J. Name., 2012, 00, 1-3
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nanoparticles(Section S8). The μ3-OH groups on UiO-66(Zr) are
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DOI: 10.1039/D0DT00472C
relatively less polarized when compared to UiO-66(Hf) due to
lower oxophilicity of Zr(IV) when compared to Hf(IV). Pd/UiO-
66(Zr) catalyst under same reaction conditions as above
afforded only 65.2 % PA conversion (vs >99% for Pd/UiO-
66(Hf)) with ST selectivity of 99.8%. This underlines the role
played by μ3-OH group on the catalytic performance of Pd-
MOF catalysts. We also carried out PA transfer hydrogenation
over commercially available Pd/C catalyst (Figure 3c). It gave
only 5.5 % PA conversion under same reaction conditions.
Thus, Pd/UiO-66(Hf) is an efficient catalyst and superior
compared to various catalysts reported for this reaction (Table
S1). The presence of –OH groups next to Pd in Pd/UiO-66(Hf)
can bring AB and PA in close proximity (Figure 3d). μ3-OH
groups of MOF can favorably adsorb AB through hydrogen
bonding and facile adsorption of PA over Pd surface is well
document.23 This will facilitate the transfer hydrogenation
through six membered transition state and bring about
catalytic synergy at the interface of Pd and MOF.
Figure 3: a) and b) Bright field-TEM image and HR-TEM of Pd/UiO-66(Hf),
c) Transfer hydrogenation of PA over different catalysts, d) Proposed
mechanism for transfer hydrogenation of PA over Pd/UiO-66(Hf) through
transition state and e) Pd/UiO-66(Hf) catalyst activity test for PA
conversion under different hydrogen sources (AB and H2). Reaction
conditions: 1 mol % of catalyst (0.0027 mmol of Pd), 0.50 mmol of AB/ 0.3
bar H2, 1 mL of 1, 4-dioxane and 0.25 mmol of PA at R.T for 30 min.
Table 2. Transfer hydrogenation of phenylacetylene using different hydrogen sources.
S.No Substrate
.
Conv.
(%)[a]
Selectivity (%)
C=C
98.5
86.4
C-C
1.5
13.6
1
2
Phenylacetylene >99.0
Ethynylcyclohex 99.5
ane
attempts to optimize an intermediate for
a stepwise
3
4
5
6
7
1-hexyne
3-hexyne
1-hexene
Styrene
99.6
14.5
1.5
95.1
4.9
nd
mechanism were unsuccessful possibly due to the absence of
such minimum on the potential energy surface. We also
checked the possibility of further reduction of ST to ethyl
benzene. The reduction barrier of ST with AB is 36.4 kcal mol-1
which is 3.8 kcal mol-1 higher than the relative free energy of
TS1 (Scheme S3). At 110 °C, the ST reduction barrier is very
much less accessible than that of PA and this resulted in the
selective formation of ST without further reduction within the
reaction timescale. Further, higlighting the role played by
solvent in the transferhydrogenation, incorporation of water
(inplace of 1,4-dioxane) as a solvent into the computations
enhanced the barrier energies of TS1 (36.0 kcal mol-1) and TS4
(39.7 kcal mol-1).
> 99.8
-
-
-
100
100
nd
5.1
Cyclohexene
nd
[a] Reaction conditions: 1 mol % of catalyst (0.0027 mmol of Pd), 0.50 mmol of
hydrogen source, 1 mL of 1, 4-dioxane and 0.25 mmol of substrate at R.T for 30
min.(nd- not determined).
On other hand, use of H2 (0.3 bar, equivalent of total
hydrogen content in AB) over Pd/UiO-66(Hf) under same
reaction conditions, yielded 47.5 % PA conversion and 55 % of
ST selectivity. This observation clearly justifies the use of AB
over H2.
To bring down the reaction temperature from 110 °C, we
synthesized Pd/UiO-66(Hf) catalyst by depositing preformed
Pd nanoparticles (3.5 ± 0.15 nm) over UiO-66(Hf) MOF surface
(Figure S1). As shown in bright field transmission electron
microscopy (TEM) image, Pd NPs were well dispersed onto the
UiO-66(Hf) MOF surface and high resolution-TEM revealed
crystalline nature of Pd nanoparticles with d-spacing
corresponding to (111) plane (Figure 3(a, b)). UiO-66(Hf) MOF
is quite stable and contains polarized μ3-OH group on its
secondary building unit.22 Over Pd/UiO-66(Hf) catalyst, full PA
conversion with ST selectivity of 98.5 % was noticed at room
temperature in 30 min (Figure 3c, Figure S6). On other hand,
over Pd+UiO-66(Hf) mixture the PA conversion was only 35.2
% (Figure 3c). This observation confirms the presence of
catalytic synergy between μ3-OH and Pd active sites. Further,
UiO-66(Zr) MOF which also has μ3-OH sites on its SBU smilar to
As shown in table 2, other alkynes also showed preference
for semihydrogenation product with AB over Pd/UiO-66(Hf).
Further, consitent with observed selectivty, transfer
hydrogenation of alkenes with AB (1-hexene styrene and
cyclohexene) under same reaction conditions did not show any
appreciable conversions. The Pd/UiO-66(Hf) catalyst found to
be recyclable up to three cycles and stable (Section S9).
Conclusions
In conclusion, the use of AB as hydrogen source instead of
H2 provided excellent selectivity towards semihydrogenation
products. Contrary to protic solvents, transfer hydrogenation
with AB in 1,4-dioxane under uncatalyzed conditions(around
110 °C) afforded >99% selectivity towards styrene. The
cooperativity between μ3-OH sites of MOF and Pd active sites
UiO-66(Hf) has been explored as
a support for Pd
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
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10 (a) A. Staubitz, A. P. Robertson, I. Manners, Chem. Rev.,
in Pd/UiO-66(Hf) catalyst brought down the reaction
temperature to room temperature. Overall, our approach
paves a way for development of sustainable process for
selective conversion of alkynes into alkenes.
2010, 110, 4079–4124; (b) X. Yang, T. FoVxi,ewHAr.ticlBe eOrnklinee,
DOI: 10.1039/D0DT00472C
Chem.Comm. 2011, 47, 2053–2055; (c) C. Chong, H. Hirao, R.
A. Kinjo, Angew. Chem. Int. Ed., 2014, 53, 3342-3346.
11 (a) F. Wang, O. Planas, J. Cornella, 2019. J. Am. Chem.
Soc., 141, 4235-4240; (b) T. M. Maier, S. Sandl, I. G.
Shenderovich, A. Jacobi von Wangelin, J. J. Weigand, R. Wolf,
Chem. Eur. J. 2019, 25, 238-245; (c) Y. Zhou, Z. Li, Y. Liu, J.
Huo, C. Chen, Q. Li, S. Niu, S. Wang, ChemSusChem., 2020
(DOI:10.1002/cssc.201902629); (d) K. Ganjehyan, B. Nişancı,
M. Sevim, A. Daştan, Ö. Metin, App. Org. Chem., 2019, 33,
4863; (e) S. F. Hou, J. Y. Chen, M. Xue, M. Jia, X. Zhai, R. Z.
Liao, C. H. Tung, W. Wang, ACS Cat., 2019, 10, 380-390.
12 (a) E. Fakioğlu, Y. Yürüm, T. N. Veziroğlu, Int. J.
Hydrog. Energ., 2004, 29, 1371; (b) Marder, B. Todd, Angew.
Chem. Int. Ed. 2007, 46, 8116; (c) F. H. Stephens, V. Pons, R.
T. Baker, Dalton Trans. 2007, 2613; (d) V. R. Bakuru, M. E.
DMello, S. B. Kalidindi, Chem. Phys. Chem., 2019, 20, 1177-
1215; e) V. R. Bakuru, B. Velaga, N. R. Peela, S. B. Kalidindi,
Chem. Eur. J., 2018, 24, 15978–15982.
Acknowledgements
The authors thank the Department of Science and Technology
(DST), Govt. of India, for funding project under INSPIRE faculty
award (IFA-14/CH-166). BVR is thankful to Manipal Academy of
Higher Education, India, for accepting this research as a part of
a Ph.D. program. We thank Kamla Netam, and Prof. Balaji R
Jagirdar from indian institute of scince for thier help with NMR
data. DS acknowledges DST for INSPIRE-Faculty fellowship
(IFA18-CH 31).
13 (a) E. Korytiaková, N. O. Thiel, F. Pape, J. E. Teichert,
Chem.Comm., 2017, 53, 732–735; (b) R. Barrios-Francisco, J.
J. García, J. Appl. Catal. A Gen., 2010, 385, 108–113; (c) Y. P.
Zhou, Z. Mo, M. P. Luecke, M. Driess, Chem.Eur. J., 2018, 24,
4780–4784; (d) C. E. Hartmann, V. Jurčík, O. Songis, C. S.
Cazin, Chem. Comm., 2013, 49, 1005-1007.
Conflicts of interest
There are no conflicts to declare.
14 (a) E. Vasilikogiannaki, I. Titilas, G. Vassilikogiannakis, M.
Stratakis, Chem. Comm., 2015, 51, 2384–2387; (b) H. Liang,
B. Zhang, H. Ge, X. Gu, S. Zhang, Y. Qin, ACS Catal., 2017, 7,
6567–6572; (c) S. Rej, M. Madasu, C. S. Tan, C. F. Hsia, M. H.
Huang, Chem. Sci., 2018, 9, 2517–2524; (d) X. Wen, X. Shi, X.
Qiao, Z. Wu, G. Bai, Chem.Comm., 2017, 53, 5372–5375.
15 (a) A. D. Sutton, A. K. Burrell, D. A. Dixon, E. B. Garner, J. C.
Gordon, T. Nakagawa, K. C. Ott, J. P. Robinson, M. Vasiliu,
Science., 2011, 331, 1426-1429; (b) O. T. Summerscales, J. C.
Gordon, Dalton Trans., 2013, 42, 10075-10084; c) (c) V. R.
Bakuru, S. B. Kalidindi, Chem. Eur. J. 2017, 23, 16456-16459
16 (a) S. B. Kalidindi, M. Indirani, B. R. Jagirdar, Inorg. chem.,
2008, 47, 7424-7429; (b) W.W. Zhan, Q. L. Zhu, Q. Xu, ACS
Catal., 2016, 6, 6892–6905; (c) S. B. Kalidindi, B. R.
Jagirdar, Inorg. chem., 2009, 48, 4524-4529.
17 (a) A. H. Chughtai, N. Ahmad, H.A. Younus, A. Laypkov, F.
Verpoort, Chem. Soc. Rev., 2015, 44, 6804-6849; (b) A.
Rossin, G. Tuci, L. Luconi, G. Giambastiani, Acs Cat., 2017, 7,
5035-5045; (c) Y. S. Kang, Y. Lu, K. Chen, Y. Zhao, P. Wang,
W. Y. Sun, Coord. Chem. Rev., 2019, 378, pp.262-280; (d) J.
Gascon, A. Corma, F. Kapteijn, F. X. Llabres i Xamena, Acs
Cat.,2014, 4, 361-378; (e) J. Lee, O. K. Farha, J. Roberts, K. A.
Scheidt, S. T. Nguyen, J. T. Hupp, Chem. Soc. Rev., 2009, 38,
1450-1459; (f) L. Chen, Q. Xu, Mat., 2019, 1, 57-89; (g) Q.
Yang, Q. Xu, H.L. Jiang, Chem. Soc. rev., 2017, 46, 4774-4808;
(h) S. Roy, P. Pachfule, Q. Xu, Eur. J. Inorg. Chem., 2016, 27,
4353-4357; (i) H. L. Jiang, T. Akita, T. Ishida, M. Haruta, Q. Xu,
J. Am. Chem. Soc., 2011, 133, 1304-1306.
18 (a) S. Yang, C. Cao, L. Peng, J. Zhang, B. Han, W. Song, Chem.
Comm., 2016, 52,3627-3630; (b) L. Chen, B. Huang, X. Qiu, X.
Wang, R. Luque, Y. Li, Chem. Sci., 2016, 7, 228-233; (c) F.
Arena, G. Cum, R. Gallo, A. Parmaliana, J. Mol. Catal. A-
Chem., 1996, 110, 235-242.
19 (a) D. J. Miller, D. M. Smith, B. Chan, L. Radom, Mol. Phys.,
2006, 104, 777–794; (b) I. Fernández, M. A. Sierra, F.P.
Cossío, J. Org.Chem., 2007, 72, 1488-1491.
20 Y. Zhao, N. E. Schultz, D. G. Truhlar, J. Chem. Theory
Comput., 2006, 2, 364–382.
21 X. Yang, L. Zhao, T. Fox, Z. X. Wang, H. Berke, Angew. Chem.
Int. Ed., 2010, 49, 2058–2062.
References
1
(a) D. Wang, D. Astruc, D. Wang, D. Astruc, Chem. Rev.,
2015, 115, 6621–6686; (b) Y. Long, S. Song, J. Li, L. Wu, Q.
Wang, Y. Liu, R. Jin, H. Zhang, ACS Cat., 2018, 8, 8506-8512;
(c) S. Song, K. Li, J. Pan, F. Wang, J. Li, J. Feng, S. Yao, X. Ge, X.
Wang, H. Zhang, S. Song, K. Li, J. Pan, F. Wang, J. Li, J. Feng,
S. Yao, X. Ge, X. Wang, H. Zhang, Adv. Mat. 2017, 29,
1605332; (d) G. Vilé, S. Wrabetz, L. Floryan, E. M. Schuster, F.
Girgsdies, D. Teschner, J. Pérez-Ramírez, Chem.Cat.Chem.,
2014, 6, 1928–1934; (e) M. P. R. J. Spee, M. Boersma, D.
Meijer, M. Q. Slagt, G. Van Koten, J. W. Geus, J. Org. Chem.
2001, 66, 1647–1656; (f) C. Moreno-Marrodan, F. Liguori, P.
Barbaro, Beilstein, J. Org. Chem., 2017, 13, 734–754.
(a) M. J. Dong, X. Wang, C. D. Wu, Adv. Func. Mat., 2019,
1908519; (b) L. Peng, J. Zhang, S. Yang, B. Han, X. Sang, C. Liu,
G. Yang, Green Chem., 2015, 17, 4178-4182; (c) H.Q. Wu, L.
Huang, J. Q. Li, A. M. Zheng, Y. Tao, L. X. Yang, W. H. Yin, F.
Luo, Inorg. chem., 2018, 57, 12444-12447; (d) X. Li, Y. Pan, H.
Yi, J. Hu, D. Yang, F. Lv, W. Li, J. Zhou, X. Wu, A. Lei, L. Zhang,
ACS Cat., 2019, 9, 4632-4641; (e) Q. Fan, S. He, L. Hao, X. Liu,
Y. Zhu, S. Xu, F. Zhang, Sci. rep., 2017, 7, 42172; (f) W. Yu, H.
Hou, Z. Xin, S. Niu, Y. Xie, X. Ji, L. Shao, RSC adv., 2017, 7,
15309-15314; (g) E. A. Karakhanov, A. L. Maximov, A.V.
Zolotukhina, Mol. Cat., 2019, 469, 98-110.
2
3
(a) R. A. Johnstone, A. H Wilby, I. D. Entwistle, Chem. Rev.,
1985, 85, 129–170; (b) G. Brieger, T. J. Nestrick, Chem. Rev.,
1974, 74, 567–580.
4
5
6
7
8
9
R. Wang, Y. Tang, M. Xu, C. Meng, F. Li, J. Org. Chem., 2018,
83, 2274–2281.
R. Nie, X. Peng, H. Zhang, X. Yu, X. Lu, D. Zhou, Q. Xia, Catal.
Sci. Technol., 2017, 7, 627–634.
C. Zhang, J. Lu, M. Li, Y. Wang, Z. Zhang, H. Chen, F. Wang,
Green Chem., 2016, 18, 2435–2442.
C. Zhu, K. Saito, M. Yamanaka, T. Akiyama, Acc. Chem. Res.,
2015, 48, 388–398.
G. R. Adair, K. Kapoor, A. L. Scolan, J. M. Williams, Tetra.
Lett., 2006, 47, 8943–8944.
P. K. Mandal, J. S. McMurray, J. Org. Chem., 2007, 72, 6599–
6601.
22 a) V. R. Bakuru, S. R. Churipard, S. P. Maradur, S. B. Kalidindi,
Dalt. Trans., 2019, 48, 843–847.
4 | J. Name., 2012, 00, 1-3
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23 (a) F. Yang, J. Tang, B. Shao, S. Gao, X. Liu, Nano-Struct.
Nano-Obj., 2019, 18, 100287; (b) R.S. hamsiev, E. I.
Finkelshtein, E.I. J Mol Model, 2018, 24, 143; c) b) V.R.
Bakuru, D. Davis, S. B. Kalidindi, Dalt. Trans., 2019, 48, 8573-
8577.
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