Mesoporous carbon derived from Vitamin B12: A high-performance bifunctional catalyst for imine formation

Article abstract of DOI:10.1039/c5cc06179b

Mesoporous carbon derived from natural vitamin B₁₂ is applied for the first time in organic synthesis and exhibits exceptionally high dual activity for imine formation via the cross-coupling of alcohols with amines and the self-coupling of primary amines using molecular oxygen or air as the terminal oxidant.

Full text of DOI:10.1039/c5cc06179b

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Mesoporous Carbon Derived from Vitamin B : A High-
12
Performance Bifunctional Catalyst for Imine Formation
Received 00th January 20xx,
Accepted 00th January 20xx
a, b
a, b
a
a
*a
Bo Chen, Sensen Shang, Lianyue Wang, Yi Zhang, and Shuang Gao
DOI: 10.1039/x0xx00000x
www.rsc.org/
Mesoporous carbon derived from natural vitamin B12 is first Besides, the introduction of heteroatoms (B, N, P, S, etc.) and
applied in organic synthesis and exhibits exceptionally high dual non-noble transition metals (Fe, Co, etc.) can further improve
activity for imine formation via the cross-coupling of alcohols with the catalytic efficiency of the materials by tuning the electronic
1
0
amines and the self-coupling of primary amines using molecular properties and generating active sites. Generally, functional
oxygen or air as the terminal oxidant.
carbons are prepared by direct pyrolysis of the precursors
containing carbon support, heteroatomic ligand and metal
1
1
Imine derivatives are common functionality in organic
intermediates, fine chemicals, and pharmaceuticals,
particularly for the synthesis of anti-cancer and anti-
salt. However, the strong interaction between these three
components is difficult to construct, which may result in the
1
0c
agglomeration of metal species during the heat treatment,
1
inflammatory drugs. In view of the wide applications,
and affect the final stability and activity of the catalysts. A
good solution is to synthesize metal complex precursors at
considerable efforts have been devoted to the direct
formation of imines since the traditional condensation method
2
involves unstable aldehydes and acid catalysts, and the
1
2
molecular level containing these elements, and more
available strategy is to utilize natural products endowing with
1
3
following two approaches have attracted more attention as
the starting reagents are readily available and dioxygen or air
can serve as the terminal oxidant: (1) the self-coupling of
carbon, heteroatom and metal, which will make the
fabrication of carbon materials greener and more sustainable,
and also promote the catalytic reactions more practical.
Recently, we have found the carbon materials derived from
macrocyclic compounds show high activity toward the self-
3
primary amines; (2) the cross-coupling of alcohols with
4
amines. Nevertheless, the main drawback of the former is
3
n
inefficient to produce hetero-coupled imines due to the
3
coupling of primary amines. However, the precursors are not
readily available, and the catalysts are also failed to produce
hetero-coupled imines. In this work, we select natural vitamin
B12 as the precursor to fabricate mesoporous carbon catalysts,
which not only inherit the high activity of the catalysts derived
from macrocyclic compounds for the self-coupling of primary
amines, but also present exceptional capability for the cross-
coupling of alcohols with amines. To the best of our
knowledge, the mesoporous carbons derived from natural
vitamin B , for the first time, are applied in organic synthesis
k-
intrinsic inevitability of the self-coupling property of amines,
m
and of the latter often requires excess amounts of alcohols
4
d-f
or amines to reach high-productivity levels.
Therefore, in
order to make the imine formation more effective and
optional, designing a catalyst with dual activity is highly
desirable. However, only noble metal catalysts such as
5
6
supported Pt catalyst, and homogeneous TEMPO systems
can simultaneously fulfill the two reactions, and
heterogeneous non-noble metal catalyst has not yet been
reported to date.
1
2
and work as heterogeneous non-noble metal catalysts
presenting dual activity for imine formation.
Mesoporous carbon materials, benefiting from their dual
8
7
roles as supports and as ‘carbocatalysts’ in their own right,
The catalyst preparation is quite simple: VB12 and colloidal
silica are well mixed followed by removing the solvent and
pyrolysis at different temperatures (400-900 °C) for 2 h under
9
have been widely applied in various organic transformations.
N atmosphere. Then, the obtained powders are treated with
2
hydrofluoric acid to remove the silica template, and the final
catalysts are labeled as m-VB -X (m represents the
1
2
mesoporous structure; VB12 is the abbreviation of vitamin B12;
X refers to the carbonization temperature).
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Initially, we focused on the cross-coupling of benzyl alcohol (Figure S5), and the elemental mapping analysis confirmed
o
1a) with equimolar amounts of aniline (2a) at 100 C under O
(
2
that the elements were homogeneously distributed
atmosphere, since no carbon-based catalyst has been throughout the whole mesoporous structure (Figure S6).
disclosed for this coupling reaction. Blank experiment Moreover, the X-ray photoelectron spectroscopy (XPS)
confirmed that the reaction hardly proceeded in the absence revealed that approximately 1.0 at% of cobalt species were
of catalyst, and commercially available VB12 only gave the survived from the acid treatment (Figure S7). Subsequently,
desired imine (3a) in 26% yield (Table 1, entries 1, 2). To our we investigated the electronic states of the catalyst by X-ray
delight, the utilization of mesoporous carbon m-VB12-6 led to absorption fine-structure (XAFS) and high resolution XPS
94% conversion with 91% selectivity (Table 1, entry 3). spectra. The near-edge spectrum of Co in m-VB12-8 was
3 4
Moreover, the selectivity can be further improved with m- different to that of Co foil, CoO, or Co O reference, further
VB12-8 providing 3a in 96% yield, and no loss of activity was revealing the absence of cobalt/cobalt oxide particles in our
observed even using air as the oxidant (Table 1, entries 4, 5). catalyst (Figure S8). The high resolution XPS spectrum of Co
Nevertheless, the temperature greatly affected the catalytic 2p / can be deconvoluted into two peaks centered at 799.9
3
2
efficiency as the conversion of 1a was gradually decreased to eV and 781.5 eV, assigned to Co-O and Co-N, respectively
1
4% performing the reaction at 80 °C (Table 1, entry 6). For (Figure 1c). And the N 1s spectrum can be fitted with three
5
7
comparison, m-CoPc-8 employing cobalt phthalocyanine peaks, including pyridinic N (398.6 eV), pyrrolic N(399.9 eV),
1
6
CoPc) as the precursor also showed moderate activity toward and oxidized N (402.6 eV) (Figure 1d). Notably, the peak at
(
the reaction, but m-Pc-8 prepared from metal-free 398.6 eV should also contain the contribution of Co-N, as its
1
7
phthalocyanine (Pc) was inefficient (Table 1, entries 7, 8). binding energies was close to pyridinic N. Previous studies
Taking the components of these catalysts into account, we can revealed that the cobalt ions stabilized by nitrogen were of
deduce that the cobalt species surviving from the acid vital importance for the generating catalysts with reasonable
1
0c, 18
treatment may play pivotal roles in this transformation. To activity in oxidation reactions,
and the nitrogen-doped
verify this hypothesis, mesoporous carbons derived from carbons can also serve as coordination sites to stabilize the
1
9
copper phthalocyanine and iron phthalocyanine were also active species. Given the cobalt ions were well coordinated
prepared, but only afforded 3a in 48% and 37% yields at the central of VB12 precursor, the agglomeration of cobalt
respectively (Table 1 entries 9, 10), further revealing the species could be greatly hindered during the subsequent heat
indispensability and superiority of cobalt to other non-noble treatment. In addition, the self-supporting feature of the
metals for this coupling reaction.
catalyst preparation enormously increased the density of
active sites. Therefore, the surviving cobalt species may
homogeneously distribute on the carbon matrix at sub-
nanoscale level, and with the advantage of the porous
structure, high activity for this cross-coupling reaction was
easily achieved.
a
Table 1 Cross-coupling of benzyl alcohol (1a) with aniline (2a) over various catalysts
Catalyst, O
2
balloon
Ph NH
2
Ph
Ph
OH
+
Ph
N
K CO
2 3
, Heptane,100 oC, 12 h
1
a
2a
3a
b
b
Entry
Catalyst
Conv. (%)
Yield (%)
1
2
3
4
-
4
4
VB12
30
94
99
99
74
75
16
52
43
26
86
96
97
67
65
12
48
37
m-VB12-6
m-VB12-8
m-VB12-8
m-VB12-8
m-CoPc-8
m-Pc-8
c
5
d
6
7
8
9
m-FePc-8
m-CuPc-8
1
0
a
Reaction conditions: 1a (0.5 mmol), 2a (0.5 mmol), K
2
CO
3
(10 mol%), heptane (1
b
mL), catalyst (10 mg), O
2
balloon, 100 °C, 12 h. Determined by GC using diphenyl
c
d
as the internal standard and confirmed by GC-MS. Air balloon. 80 °C.
The microstructure of m-VB12-8 was first analyzed by the
2
N sorption. And the corresponding Brunauer-Emmett-Teller
2
BET) surface area and the average pore size were 637 m /g
(
and 12.3 nm, respectively (Figure S4). The porous structure
was also observed from the scanning electron microscopy
Figure 1 (a) SEM image, (b) TEM image, and (c) high-resolution Co 2p3/2 and (d) N 1s
(
SEM) and transmission electron microscopy (TEM) images
Figure 1a, b). Whereas, we did not find any cobalt-containing
XPS spectra of m-VB12-8.
(
nanoparticles on the catalyst, since the etching agent may
dissolve the silica template and cobalt/cobalt oxide particles at
With the optimized conditions in hand, we then examined
the scope of present catalytic system for various alcohols and
amines. As depicted in Table 2, benzylic alcohols can smoothly
react with 2a to afford the desired imines in excellent yields
1
4
the same time. Nevertheless, the energy-dispersive X-ray
EDX) spectrum showed the presence of C, N, O, P and Co
(
2
| J. Name., 2012, 00, 1-3
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b
b
regardless of the presence of electron-donating or electron-
withdrawing groups (Table 2, entries 1-3). Besides,
unsaturated alcohol such as cinnamyl alcohol can also be
readily transformed into the corresponding imine without loss
of the C=C bond (Table 2, entry 4). When more challenging
aliphatic alcohol was tested, a relatively low yield was
observed (Table 2, entry 5). As for amine part, substituted
anilines, cyclical and aliphatic amines all reacted efficiently
with 1a to produce the imine products in excellent yields
Entry
Catalyst
Conv. (%)
Yield (%)
1
2
3
4
5
6
VB12
15
7
14
7
VB12-6
m-VB12-6
m-CoPc-6
m-Pc-6
97
69
85
36
92
67
82
23
3 4
mpg-C N
a
b
Reaction conditions: 4a (5 mmol), catalyst (20 mg), O
2
balloon, 8 h, 100 °C.
Determined by GC using diphenyl as the internal standard and confirmed by GC-
MS.
(Table 2, entries 6-9).
a
Table 2 Cross-coupling of alcohols with amines to imines catalyzed by m-VB12-8
Subsequently, we investigated various amines for this
coupling reaction. As summarized in Table 4, excellent yields
were observed for the self-coupling of both electron-rich
3 3 3
(OCH and CH ) and electron-deficient (F, Br, and CF )
benzylamines (Table 4, entries 2-6). Moreover, heteroatom-
containing amines were also well tolerated, providing the
corresponding imines in good yields (Table 4, entries 7-9).
Whereas, the self-coupling of n-hexylamine was difficult to
proceed owing to the inactive α-hydrogen (Table 4, entry 10).
Besides, secondary amine and cyclic amine were suitable for
this reaction leading to the desired imines in moderate to good
yields (Table 4, entries 11-12).
a
Table 4 m-VB12-6-catalyzed the self-coupling of amines to give homo-coupled imines
a
2 3
Reaction conditions: 1 (0.5 mmol), 2 (0.5 mmol), K CO (10 mol%), heptane (1
b
mL), catalyst (10 mg), air balloon, 100 °C, 12 h. Determined by GC and confirmed
by GC-MS. Numbers in parentheses referred to yields of isolated products
To further extend the applications, we examined the
activity of the prepared materials for the self-coupling of
benzylamine (4a) under neat conditions, which was an
effective strategy to homo-coupled imines. The precursor VB12
,
similar to the literature report of cobalt complex, was
3
inefficient under mild reaction conditions, and only gave the
o
corresponding imine (5a) in 14% yield after 8 h (Table 3, entry
1
). Besides, direct pyrolysis of VB12 without any template
under N atmosphere would result in an inactive material
Table 3, entry 2). In contrast, mesoporous carbon m-VB12-X
2
(
(
(
X=4, 5, 6, 7, 8, and 9) were high active toward the reaction
Table S2, entries 1-7), and m-VB12-6 has sufficient catalytic
a
b
Reaction conditions: 4 (5 mmol), catalyst (20 mg), O
2
balloon, 8 h, 100 °C.
activity to give 5a in 92% yield (Table 3, entry 3). Notably,
compared to m-CoPc-6, metal-free m-Pc-6 presented higher
activity for this transformation, which strongly demonstrated
that the surviving cobalt species were not necessary to this
self-coupling reaction(Table 3, entries 4, 5). Besides,
Determined by GC and confirmed by GC-MS. Numbers in parentheses referred to
c
d
yields of isolated products. N-benzylaniline as the substrate 18 hours.
To identify the effectiveness and reusability of m-VB12-6, a
1
00 mmol scale self-coupling of 4a was performed, and the
mesoporous graphitic carbon nitride (mpg-C
in 23% yield (Table 3, entry 6), implying the structure of the
precursor also affected the final activity of the catalyst. Based
3 4
N ) only afforded
reaction proceeded smoothly to provide the desired 5a in 95%
5a
yield (Table 5). Notably, the catalyst/substrate ratio was just
0
.47 wt% and was one magnitude lower than that of reported
3
3n
g, 3l
on the above results and previous reports, we proposed that
the defect sites on the carbon matrix rather than the metal
species catalyzed the self-coupling of primary amines, and the
accessible mesoporous structure can greatly promote the
mass transfer and the active site’s exposure (Scheme S2).
carbon-based catalytic systems,
and the recovered catalyst
can also be used at least five times without any appreciable
loss of activity on this 100 mmol scale. In addition, the hot-
filtration test showed that no further consumption of 1a took
place after the catalyst was filtered at the conversion of 36%,
suggesting the catalysis was truly heterogeneous (Figure S10).
a
Table 3 Self-coupling of benzylamine (4a) over different catalysts
a
Table 5 Recycling of m-VB12-6 for the self-coupling of benzylamine (4a)
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Zhang, D. Milstein, Angew. Chem. Int. Ed. 2010, 49, 1468-
1471; (c) B. Chen, J. Li, W. Dai, L. Wang, S. Gao, Green Chem.
Run
0
1
2
3
4
5
b
Yield (%)
95
92
94
95
95
93
2
014, 16, 3328-3334; (d) L. Zhang, W. Wang, A.-Q. Wang, Y.-
a
Reaction conditions: 4a (100 mmol), m-VB12-6 (50 mg), O
2
balloon, 48 h, 120 °C.
T. Cui, X. Yang, Y. Huang, X. Liu, W. Liu, J.-Y. Son, H. Oji, T.
Zhang, Green Chem. 2013, 15, 2680-2684; (e) E. L. Zhang, H.
W. Tian, S. D. Xu, X. C. Yu, Q. Xu, Org. Lett. 2013, 15, 2704-
b
Determined by GC and confirmed by GC-MS.
2
2
707; (f) M. Tamura, K. Tomishige, Angew. Chem. Int. Ed.
015, 54, 864-867.
In summary, we have developed an efficient, bifunctional
and reusable mesoporous carbon catalyst for imine formation.
The m-VB12-X catalyst is prepared by simple thermolysis of
natural vitamin B12 with silica template. The high catalytic
efficiency of the catalysts is not only manifested at the self-
coupling of primary amines, affording the corresponding
homo-coupled imines, but also reflected at the cross-coupling
of alcohols with amines, providing more diverse types of
5
6
7
W. He, L. Wang, C. Sun, K. Wu, S. He, J. Chen, P. Wu, Z. Yu,
Chem. Eur. J. 2011, 17, 13308-13317.
E. Zhang, H. Tian, S. Xu, X. Yu, Q. Xu, Org. Lett. 2013, 15,
2704-2707.
(a) X. Xu, Y. Li, Y. Gong, P. Zhang, H. Li, Y. Wang, J. Am. Chem.
Soc. 2012, 134, 16987-16990; (b) P. Zhang, Y. Gong, H. Li, Z.
Chen, Y. Wang, Nat. Commun. 2013, 4, 1593; (c) L. Geng, X.
Zhang, W. Zhang, M. Jia, G. Liu, Chem. Commun. 2014, 50,
imines. Control experiments combined
with
the
2
965-2967.
H. Yang, X. Cui, X. Dai, Y. Deng, F. Shi, Nat. Commun. 2015, 6,
478.
(a) D. R. Dreyer, C. W. Bielawski, Chem. Sci. 2011, 2, 1233-
characterizations reveal that the defect sites on the carbon
matrix catalyze the self-coupling of primary amines, while the
surviving cobalt species play important roles in the cross-
coupling of alcohols with amines. This work may provide a new
strategy to design bifunctional catalysts for imine formation
and make the synthesis of imines more effective and flexible
as well.
8
9
6
1
1
240; (b) D. S. Su, S. Perathoner, G. Centi, Chem. Rev. 2013
13, 5782-5816; (c) G.-P. Hao, M. Oschatz, W. Nickel, M.
,
Adam, S. Kaskel, Curr. Org. Chem. 2014, 18, 1262-1279; (d) Y.
Kuang, N. M. Islam, Y. Nabae, T. Hayakawa, M.-a. Kakimoto,
Angew. Chem. Int. Ed. 2010, 49, 436-440; (e) D. R. Dreyer, H.
P. Jia, C. W. Bielawski, Angew. Chem. Int. Ed. 2010, 49, 6813-
We gratefully acknowledge the financial support from the
National Natural Science Foundation of China (21403219), and
the National Engineering Laboratory for Methanol to Olefins.
We appreciate Dr. Rui Si of Shanghai Institute of Applied
Physics for the aid of XAFS measurement.
6
816; (f) J. Long, X. Xie, J. Xu, Q. Gu, L. Chen, X. Wang, ACS
Catal. 2012, 2, 622-631; (g) H. Watanabe, S. Asano, S.-i.
Fujita, H. Yoshida, M. Arai, ACS Catal. 2015, 5, 2886-2894; (h)
X.-H. Li, M. Antonietti, Angew. Chem. Int. Ed. 2013, 52, 4572-
4
576; (i) H. Wang, X. Zheng, H. Chen, K. Yan, Z. Zhu, S. Yang,
Chem. Commun. 2014, 50, 7517-7520; (j) J. Zhang, X. Liu, R.
Blume, A. Zhang, R. Schlögl, D. S. Su, Science 2008, 322, 73-
7
7; (k) Y. Gao, G. Hu, J. Zhong, Z. Shi, Y. Zhu, D. S. Su, J. Wang,
Notes and references
X. Bao, D. Ma, Angew. Chem. Int. Ed. 2013, 52, 2109-2113; (l)
J.-H. Yang, G. Sun, Y. Gao, H. Zhao, P. Tang, J. Tan, A.-H. Lu, D.
Ma, Energy Environ. Sci. 2013, 6, 793-798.
1
(a) S.-I. Murahashi, Angew. Chem. Int. Ed. Engl. 1995, 34,
2
1
443-2465; (b) S. Kobayashi, H. Ishitani, Chem. Rev. 1999, 99,
069-1094; (c) Z.-Y. Liu, Y.-M. Wang, Z.-R. Li, J.-D. Jiang, D. W. 10 (a) J. P. Paraknowitsch, A. Thomas, Energy Environ. Sci. 2013
,
Boykin, Bioorg. Med. Chem. Lett. 2009, 19, 5661-5664.
(a) R. D. Patil, S. Adimurthy, Asian J. Org. Chem. 2013, 2, 726-
6, 2839-2855; (b) R. V. Jagadeesh, A.-E. Surkus, H. Junge, M.-
2
3
M. Pohl, J. Radnik, J. Rabeah, H. Huan, V. Schünemann, A.
Brückner, M. Beller, Science 2013, 342, 1073-1076; (c) R. V.
Jagadeesh, H. Junge, M.-M. Pohl, J. r. Radnik, A. Brückner, M.
Beller, J. Am. Chem. Soc. 2013, 135, 10776-10782; (d) D.
Banerjee, R. V. Jagadeesh, K. Junge, M. M. Pohl, J. Radnik, A.
Brückner, M. Beller, Angew. Chem. Int. Ed. 2014, 53, 4359-
4363.
7
5
44; (b) M. Largeron, Eur. J. Org. Chem. 2013, 2013, 5225-
235.
(a) F. Su, S. C. Mathew, L. Möhlmann, M. Antonietti, X.
Wang, S. Blechert, Angew. Chem. Int. Ed. 2011, 50, 657-660;
(b) X. Lang, H. Ji, C. Chen, W. Ma, J. Zhao, Angew. Chem. Int.
Ed. 2011, 50, 3934-3937; (c) S. Furukawa, Y. Ohno, T.
Shishido, K. Teramura, T. Tanaka, ACS Catal. 2011, 1, 1150-
1
2
11 M. Lefèvre, E. Proietti, F. Jaouen, J.-P. Dodelet, Science 2009
324, 71-74.
12 (a) L. Lin, Q. Zhu, A.-W. Xu, J. Am. Chem. Soc. 2014, 136,
,
153; (d) M. Largeron, M. B. Fleury, Angew. Chem. Int. Ed.
012, 51, 5409-5412; (e) H. Yuan, W.-J. Yoo, H. Miyamura, S.
Kobayashi, J. Am. Chem. Soc. 2012, 134, 13970-13973; (f) S.-i.
Naya, K. Kimura, H. Tada, ACS Catal. 2012, 3, 10-13; (g) C. Su,
M. Acik, K. Takai, J. Lu, S.-j. Hao, Y. Zheng, P. Wu, Q. Bao, T.
Enoki, Y. J. Chabal, K. Ping Loh, Nat. Commun. 2012, 3, 1298;
(h) M. Largeron, M. B. Fleury, Science 2013, 339, 43-44; (i) X.
Qiu, C. Len, R. Luque, Y. Li, ChemSusChem 2014, 7, 1684-
11027-11033; (b) Z. Li, G. Li, L. Jiang, J. Li, G. Sun, C. Xia, F. Li,
Angew. Chem. Int. Ed. 2014, 53, 1-6.
13 M.-M. Titirici, R. J. White, N. Brun, V. L. Budarin, D. S. Su, F.
del Monte, J. H. Clark, M. J. MacLachlan, Chem. Soc. Rev.
2015, 44, 250-290.
14 K. T. Lee, X. Ji, M. Rault, L. F. Nazar, Angew. Chem. Int. Ed.
2009, 48, 5661-5665.
15 G. Wu, Z. Chen, K. Artyushkova, F. H. Garzon, P. Zelenay, ECS
Trans. 2008, 16, 159-170.
1688; (j) M. Largeron, M. B. Fleury, Chem. Eur. J. 2015, 21,
3815–3820; (k) R. D. Patil, S. Adimurthy, Adv. Synth. Catal.
2011, 353, 1695-1700; (l) H. Huang, J. Huang, Y.-M. Liu, H.-Y.
He, Y. Cao, K.-N. Fan, Green Chem. 2012, 14, 930-934; (m) A.
Monopoli, P. Cotugno, F. Iannone, F. Ciminale, M. M.
16 U. Koslowski, I. Herrmann, P. Bogdanoff, C. Barkschat, S.
Fiechter, N. Iwata, H. Takahashi, H. Nishikori, ECS Trans.
2008, 13, 125-141.
17 L. Zhang, A. Wang, W. Wang, Y. Huang, X. Liu, S. Miao, J. Liu,
T. Zhang, ACS Catal. 2015. 5, 6563-6572.
18 (a) J. Deng, H. J. Song, M. S. Cui, Y. P. Du, Y. Fu,
ChemSusChem 2014, 7, 3334-3340; (b) W. Zhong, H. Liu, C.
Bai, S. Liao, Y. Li, ACS Catal. 2015, 5, 1850-1856.
19 R. Nie, J. Shi, W. Du, W. Ning, Z. Hou, F.-S. Xiao, J. Mater.
Chem. A 2013, 1, 9037-9045.
Dell'Anna, P. Mastrorilli, A. Nacci, Eur. J. Org. Chem. 2014,
014, 5925-5931; (n) B. Chen, L. Wang, W. Dai, S. Shang, Y.
2
Lv, S. Gao, ACS Catal. 2015, 2788-2794; (o) S. Zhao, C. Liu, Y.
Guo, J.-C. Xiao, Q.-Y. Chen, J. Org. Chem. 2014, 79, 8926-
8931; (p) S. Biswas, B. Dutta, K. Mullick, C.-H. Kuo, A. S.
Poyraz, S. L. Suib, ACS Catal. 2015, 5, 4394−4403.
(a) H. Sun, F.-Z. Su, J. Ni, Y. Cao, H.-Y. He, K.-N. Fan, Angew.
Chem. Int. Ed. 2009, 48, 4390-4393; (b) B. Gnanaprakasam, J.
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