Cu/Picolinamides-Catalyzed Coupling of (Hetero)aryl Halides with Secondary Phosphine Oxides and Phosphite?

Article abstract of DOI:10.1002/cjoc.202100354

Some 4-hydroxy-picolinic acid derived amides were revealed as more efficient ligands for Cu-catalyzed coupling of (hetero)aryl halides with secondary phosphine oxides and phosphites. Only 3—5 mol% CuI and ligands were required to ensure coupling with a number of (hetero)aryl bromides and iodides to complete at 120 ^oC in 10—20 h.

Full text of DOI:10.1002/cjoc.202100354

Chinese Journal
of Chemistry
CJC
中 国 化 学 - An International Journal
Accepted Article
Title: Cu/Picolinamides-Catalyzed Coupling of (Hetero)aryl Halides with Secondary
Phosphine Oxides and Phosphite
Authors: Chao Fang, Bangguo Wei,* and Dawei Ma*
This manuscript has been accepted and appears as an Accepted Article online.
This work may now be cited as: Chin. J. Chem. 2021, 39, 10.1002/cjoc.202100354.
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published online in Early View: http://dx.doi.org/10.1002/cjoc.202100354.
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Cite this paper: Chin. J. Chem. 2021, 39, XXX—XXX. DOI: 10.1002/cjoc.202100XXX
Cu/Picolinamides-Catalyzed Coupling of (Hetero)aryl Halides
with Secondary Phosphine Oxides and Phosphite
Chao Fang,a Bangguo Wei,*,a and Dawei Ma*,b
aDepartment of Natural Medicine, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China
bState Key Laboratory of Bioorganic & Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Or-
ganic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Science, 345 Lingling Lu, Shanghai 200032, China
Dedicated to Professor Christian Bruneau for his out-standing contribution to catalysis
Keywords
Aryl phosphine oxides | Coupling | Aryl halides | Copper | Picolinamide
Main observation and conclusion
Some 4-hydroxy-picolinic acid derived amides were revealed as more efficient ligands for Cu-catalyzed coupling of (hetero)aryl halides
with secondary phosphine oxides and phosphites. Only 3-5 mol% CuI and ligands were required to ensure coupling with a number of
(hetero)aryl bromides and iodides complete at 120 oC in 10-20 h.
Comprehensive Graphic Content
OH
O
P
R
3-5 mol% CuI
or
X
O
H P R
R
L6 L7
3-5 mol%
H
+
R
Y
het
N
Y
het
lowest catalytic loadings
for Cu-catalyzed
N
O
L6
Me
C-P bond formation
a
range of
suitable for wide
=
examples
examples
X
Br, 31
OH
bromides
(hetero)aryl
X= 14
I,
Me
H
N
N
O
L7
Me
OH
5 mol%
CuI
O
mol%
5
O
ligand
+
O
H P Ph
Ph
inexpensive
coupling
Ph P
N
O
Br
N
Ph
t-Bu
t-Bu
reduction
O
PPh2 N
t-BuPHOX
t-Bu
S
( )-
*E-mail: madw@sioc.ac.cn, bgwei1974@fudan.edu.cn
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Supporting Information
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© 2021 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
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through the copyediting, typesetting, pagination and proofreading process which may lead to
differences between this version and the Version of Record. Please cite this article as doi:
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First author et al.
Report
this ligand seemed to have little influence to the reaction, as evi-
dent from that yields were slightly dropped in case of L7 and L8 as
the ligands (compare entries 6-8). However, switching the acid
part in this ligand dramatically decreased the reaction yields of 3a
(entries 9 and 10), indicating that subtle change in the pyridine
ring of the ligands could alter the reaction course greatly.
Background and Originality Content
(Hetero)aryl phosphine oxides are important compounds that
have been frequently used for assembling phosphine ligands. Di-
rect coupling of (hetero)aryl halides with phosphine oxides repre-
sents one of the most convenient approaches for preparing these
molecules.[1-11] Since it was discovered in 1980 by Hirao group,[2]
Pd-catalyzed coupling of C(sp2) electrophiles with secondary
phosphites and phosphine oxides has been intensively investigat-
ed and a great number of electrophiles such as aryl halides,[3] tri-
flates,[4] boronic acids,[5] and aryl sulfonates[6] have been succes-
sively employed as the coupling partners. However, cost issue of
palladium and requiring relatively high catalytic loadings (typically
5-10 mol%) limited its practical usage.[1] Consequently much at-
tention has been directed to development of alternative catalysts
with less expensive transition metals in recent years.[1] While
Ni-catalyzed C-P coupling has made significant progress under the
assistance of either ligands[7] or light irradiation,[8] Cu-catalyzed
C-P bond formation has been less explored. Until now,
Cu/ligand-catalyzed arylation of secondary phosphites or phos-
phine oxides is still limited to using aryl iodides and some special
aryl bromides as substrates, even at higher catalytic loadings (>20
mol%).[9,10] Accordingly, discovery of a more efficient Cu-based
catalytic system for C-P coupling is of great interest.
Table 1 CuI-catalyzed coupling of 2-bromo-6-methoxy-naphthalene with
diphenylphosphine oxide under the assistance of different ligandsa
O
CuI,
K
solvent
MeO
ligand
2CO3
Ph
Br
+
O
P
P
H
Ph
Ph
MeO
Me
Ph
2a
1a
3a
Me
HO
Me
O
O
O
NHBn
N
N
N
H
H
H
Ph
L3
O
Me
Ph
2
2
L1
L2
(BHMPO)
(BPMPO)
X
HO
HO
O
Me
O
Me
Me
O
N
H
HN
N
HN
N
HN
OH
X
:
:
=
:
:
=
=
L7
L8
L4
L5
X
X
X
X
H
OH
L6
Me
=
OMe
(HMNPA)
O
O
Scheme 1 General methods for metal-catalyzed coupling of C(sp2) electro-
philes with secondary phosphites or phosphine oxides
N
HN
N
HN
L10
HO
work
Previous
L9
Me
Me
O
P
R
X
+
O
P
R
metal catalyst
entry
1
conditions
yield (%)b
0
H
R
Y
R
Y
10 mol% CuI, 10 mol% L1, DMSO, 100 oC
10 mol% CuI, 10 mol% L2, DMSO, 100 oC
10 mol% CuI, 10 mol% L3, DMSO, 100 oC
10 mol% CuI, 10 mol% L4, DMSO, 100 oC
10 mol% CuI, 10 mol% L5, DMSO, 100 oC
10 mol% CuI, 10 mol% L6, DMSO, 100 oC
10 mol% CuI, 10 mol% L7, DMSO, 100 oC
10 mol% CuI, 10 mol% L8, DMSO, 100 oC
10 mol% CuI, 10 mol% L9, DMSO, 100 oC
10 mol% CuI, 10 mol% L10, DMSO, 100 oC
10 mol% CuI, 10 mol% L6, DMF, 100 oC
10 mol% CuI, 10 mol% L6, i-PrOH, 100 oC
10 mol% CuI, 10 mol% L6, n-BuOH, 100 oC
10 mol% CuI, 10 mol% L6, t-BuOH, 100 oC
10 mol% CuI, 10 mol% L6, MeCN, 100 oC
10 mol% CuI, 10 mol% L6, dioxane, 100 oC
5 mol% CuI, 5 mol% L6, i-PrOH, 100 oC
5 mol% CuI, 5 mol% L6, i-PrOH, 120 oC
=
=
Metal Pd, with
X
Br, Cl, OTf, SO
2
I,
irradiation, X
R,
phosphine ligands,
ligands light
ligands (high
B(OH)2
2
3
0
=
or
=
Metal Ni, with
Br, Cl
I,
Br
=
=
Metal Cu, with
loadings), X
limited)
O
I,
(very
8
work
This
R
4
21
40
74
65
69
36
11
70
93
96
11
27
0
P
X
O
3-5 mol% CuI &
ligand
+
R
Y
het
Y
het
H
P
R
R
5
=
X
Br, I
6
7
Results and Discussion
8
Results
9
In recent years, we have found that some oxalic diamides[12,13]
and N-heterocycle-embodied amides[14] are more powerful ligands
that can be used to solve many existing problems in Cu-catalyzed
arylation of nucleophiles. As an extension of this work, in this pa-
per, we explored the possibility of using these ligands to promote
Cu-catalyzed coupling reaction of aryl bromides with secondary
phosphine oxides. As indicated in Table 1, we selected the cou-
pling of 2-bromo-6-methoxynaphthalene with diphenylphosphine
oxide as the model reaction to seek suitable reaction conditions.
Initially, three oxalic diamides L1-L3 that displayed excellent activ-
ity to promote Cu-catalyzed C-N or C-O bond formation were ex-
amined.[13] It was found that under the catalysis of 10 mol% CuI
and ligand, only L3 led to the formation of the desired product 3a
10
11
12
13
14
15
16
17
18
75
88
o
in 8% yield after heating the reaction mixture in DMSO at 100 C
aGeneral conditions: 1a (1.0 mmol), 2a (1.1 mmol), CuI (0.05-0.1 mmol), 20
h. The yield was determined by 1H NMR analysis of crude products using
DMAc as the internal standard.
for 20 h (entries 1-3). Then we moved our attention to pro-
line-derived amides that showed superior activity in Cu-catalyzed
coupling of (hetero)aryl halides with sulfinic acid salts,[14] and
were pleased that the yields of 3a jumped to 21% and 40% when
amides L4 and L5 were applied, respectively (entries 4 and 5).
Further exploration revealed that 4-hydroxypicolinic acid derived
amide L6 (4-hydroxy-N-(2-methylnaphthalen-1-yl)picolinamide,
HMNPA) gave a better yield (entry 6). Changing the aniline part in
b
It is notable that 6-hydroxypicolinamide L10 has showed ex-
cellent activity toward Cu-catalyzed coupling of heteroaryl primary
amines with (hetero)aryl bromide.[15] In our case, it was much less
potent than 4-hydroxypicolinamide L6. With the amide L6 as the
ligand, we also checked the solvent effect, and found that while
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Running title
Chin. J. Chem.
DMF gave a similar result (entry 11), using i-PrOH or n-BuOH as
the solvent significantly improved the yields (entries 12 and 13),
and other solvents like t-BuOH, MeCN and dioxane led to low
yields or no conversion (entries 14-16). Reducing the catalytic
loading to 5 mol% caused incomplete conversion (entry 17).
the corresponding heteroaryl phosphine oxides 3o-3u. Notably,
coupling with 2-bromothiophene was rather sluggish, and incom-
plete conversion was seen even increasing the catalytic loading to
10 mol% (3o). When 2,6-dibromopyridine was utilized, double
coupling occurred to furnish diphosphonate 3s. Additionally,
switching diphenylphosphine oxide to two other diarylphosphine
oxides was possible, affording 3v-3y in 62-80% yields. Further-
more, coupling with diisopropyl phosphonate was tested, and the
desired coupling products 3z-3ae were isolated, although the
yields were relatively low because of slower conversion.
o
However, increasing the reaction temperature to 120 C could
solve this problem (entry 18). Based on these studies, we con-
cluded the optimized reaction conditions are using 5 mol% CuI
and L6 as the catalytic system, i-PrOH as the solvent, and con-
ducting the reaction at 120 oC.
Scheme 2 CuI/HMNPA catalyzed coupling reaction of (hetero)aryl bromides
Scheme 3 CuI/L7-catalyzed coupling reaction of (hetero)aryl iodides with
with secondary phosphine oxides and diisopropyl phosphonatea
secondary phosphine oxides.a
OH
5 mol% CuI
L6
OH
O
P
O
P
R
5 mol%
or
X
+
O
P
R
3 mol% CuI
L7
I
+
O
P
K
Na
2CO3
2CO3
Me
O
H
R
3 mol%
H
H
O
R
het
het
N
het
H
R
R
i-PrOH
N
het
N
K
i-PrOH
2CO3
,
R
2
N
120 o 20 h
R
2
120 o 10 h
Y
Y
O
1
C,
3
Y
C,
O
4
L6
Y
Me
3
L7
Me
OH
Ph
O
P
O
O
P
Ph
Ph
Ph
Ph
O
O
O
P
Ph
Ph
Ph
P
Y
P
O
O
P
Y
P
P
Ph
Ph
Ph
Me
Ph
Ph
Ph
Ph
Ph
Y
3b Y
Y
3b Y
Y
:
=
=
3i Y
OMe, 83%
:
=
=
3m
OMe, 78%
Me, 66%
(81%)
O
:
=
=
=
: =
3af Y
:
=
=
OMe, 81% 3i Y
74%
Me, 93%
OMe,
b
:
3j Y
COMe, 87%
:
3c Y
3l
:
=
3ag Y Ph,
59%
(44%)
:
3c Y
Me, 90%
3d Y Ph,
=
3e Y
H,
3f Y NH2
:
3j Y
COMe,
78%b
3ah
CF3 75%b
=
,
(90%)
Me
:
3k Y
:
=
3d Y Ph,
O
85%
:
:
:
91%
84%
79%
54%,
O
P
O
P
R
N
P
:
=
3e Y
70%
H,
Ph
Me
Ph
Ph
Ph
91%b
:
=
3f Y NH2
75%
,
=
,
O
Ph
Ph
:
=
3p R
b
O
P
H,
:
=
=
:
=
COMe, 93%
3g Y
COMe, 83%
3g Y
P
S
b
:
=
Me
Me
3q R
b
Me, 94%
49%c
:
3h Y
CN, 71%
3o
3n
N
(21%,
)
(84%)
O
MeOC
O
P
Ph
MeOC
Me
P
O
P
O
O
O
3w
Ph
(90%)
N
Ph
N
N
P
Ph
(56%)
P
N
P
Me
H
Ph
Ph
Ph
Ph
3ai
3y
(89%)
Ph
b
Ph
b
Ph
Ph
N
b
b
3t
3s
3u
aGeneral conditions: 4 (2.0 mmol), 2 (2.3 mmol), CuI (0.06 mmol), L7 (0.06
mmol), K2CO3 (3.0 mmol), i-PrOH (2.0 mL), 120 oC, 10 h, isolated yield. bCuI
(0.12 mmol) and L7 (0.12 mmol) were used.
3r
(75%)
Me
(85%)
(87%)
(60%)
Me
O
P
i-PrO)
(
2OP
O
P
Me
Me
In view of this encouraging result, we envisioned that further
reducing the catalytic loadings would be possible if more reactive
aryl iodides were employed as the coupling partners. As a result,
we utilized 3 mol% CuI and ligands to examine the coupling reac-
tion of 4-iodoanisole with diphenylphosphine oxide, and quickly
discovered that the ligand L7 was slightly better than L6. In this
case reaction completed after 10 h to provide 3b in 81% yield
(Scheme 2). The other para- and meta-substituted aryl iodides
tested also worked well, giving rise to 3c-3g, 3i and 3j in good to
excellent yields. In case of 1-(3-iodophenyl)ethan-1-one (3j), in-
creasing the catalytic loading to 6 mol% gave a better yield, im-
plying that its reactivity was significantly lower than that of
3-iodoanisole. Pleasingly, coupling with two ortho-substituted aryl
iodides was possible, providing 3af and 3ag in 93% and 59% yields,
respectively. In addition, changing the coupling partners to
1-iodonaphthalene (3ah), 6-iodoquinazolines (3ai) and two other
diarylphosphine oxides (3w and 3y) did not affect the catalytic
efficiency.
The synthetic usage of the present catalytic system was
demonstrated by preparing (S)-t-BuPHOX, a valuable ligand for
several Pd-catalyzed reactions.[10a,b] In an attempt to prepare this
ligand in a more convenient and economical way, Stoltz and
coworkers successively applied the copper-catalyzed C-P bond
formation between bromide 5 (Scheme 3) and diphylphosphine
oxide 2a,[10b] but higher catalytic loadings were required to ensure
the complete conversion (>12.5 mol % CuI and >87.5 mol %
N,N’-dimethylethylenediamine). With more efficient ligands in
hand, we found that a similar result was observed using only 5
mol% CuI and L7 in the coupling step, and the resultant coupling
product 6 was reduced with Ph2SiH3 to afford (S)-t-BuPHOX in 70%
Y
3z
(44%)
Y
-
O
Me
OMe, 66%
Me
OMe, 80%
:
=
3v Y
:
=
3x Y
b
:
=
COMe, 62%
3w Y
77%b
:
=
3y Y
COMe,
-
-
i PrO)
2OP
(
i PrO)
2OP
(
i PrO)
2OP
(
Y
N
:
:
:
=
=
=
3aa Y
3ab Y
3ac Y Ph,
OMe, 59%
COMe, 55%
3ae
3ad
S
(65%)
(59%)
63%
aGeneral conditions: 1 (1.0 mmol), 2 (1.1 mmol for secondary phosphine
oxides, 1.5 mmol for diisopropyl phosphonate), CuI (0.05 mmol), L6 (0.05
mmol), K2CO3 (1.5 mmol), i-PrOH (1.0 mL), 120 oC, 20 h, isolated yield.
bNa2CO3 as the base. cCuI (0.1 mmol) and L6 (0.1 mmol) were used.
The established optimal reaction conditions were then exam-
ined with a series of (hetero)aryl bromides, secondary phosphine
oxides and phosphites. As summarized in Scheme 1, coupling of
diphenylphosphine oxide with aryl bromides with either elec-
tron-donating or electron-withdrawing groups at the para-posi-
tion proceeded smoothly to provide 3b-3h in 66-85% yields. Three
meta-substituted aryl bromides also worked well, leading to the
formation of 3i-3j in 75-87% yields. However, ortho-substituted
substrates are difficult ones under the present conditions, as evi-
dent from that 3l was obtained in a low yield. After checked the
coupling reaction with 5-bromo-benzo[d][1,3]dioxole (3m) and
2-bromonaphthalene (3n), we moved our attention to coupling
with heteroaryl bromides, and were pleased that both elec-
tron-rich and electron-poor substrates were applicable, delivering
Chin. J. Chem. 2021, 39, XXX－XXX
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First author et al.
Report
overall yield. Noteworthy is that the reaction conditions were
essential for the coupling step. In our initial try by using standard
conditions as outlined in Scheme 1, phosphonate 6 was isolated in
a low yield, mainly because debromination of 5 occurred. Fortu-
nately, switching the ligand from L6 to L7, and solvent from i-PrOH
to n-BuOH greatly inhibit this side reaction.
Supporting Information
The supporting information for this article is available on the
WWW under https://doi.org/10.1002/cjoc.2021xxxxx.
Acknowledgement
Scheme 4 Synthesis of (S)-t-BuPHOX through CuI/L7-catalyzed arylation of
diphylphosphine oxide
The authors are grateful to Chinese Academy of Sciences
(supported by the Strategic Priority Research Program, grant
XDB20020200 & QYZDJ-SSW-SLH029) and the National Natural
Science Foundation of China (grant 21621002, 21831009 and
21991110) for their financial support.
5 mol% CuI
O
mol%
L7
5
O
O
+
H
P
Ph
Na
2CO
equiv)
3 (1.5
Ph
P
N
O
Ph
Br
N
o
n
-BuOH, 120
20
h
C,
Ph
t-Bu
2a
5
t-Bu
6
References
Ph
2SiH2
140 o
C
70% for
2 steps
For selected reviews, see: (a) Tappe, F. M. J.; Trepohl, V. T.; Oes-
treich, M. Transition-metal catalyzed C−P cross-coupling reactions.
Synthesis 2010, 3037−3066; (b) Demmer, C. S.; Krogsgaard-Larsen, N.;
Bunch, L. Review on modern advances of chemical methods for the
introduction of a phosphonic acid group. Chem. Rev. 2011, 111,
7981−8006.
O
PPh2
N
t-Bu
t-BuPHOX
S
( )-
(a) Hirao, T.; Masunaga, T.; Ohshiro, Y.; Agawa, T. Stereoselective
synthesis of vinylphosphonate. Tetrahedron Lett. 1980, 21,
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el synthesis of dialkyl arenephosphonates. Synthesis 1981, 56−57.
For selected examples, see: (a) Kalek, M.; Jerowska, M.; Stawinski, J.
Preparation of Arylphosphonates by Palladium(0)-Catalyzed
Cross-Coupling in the Presence of Acetate Additives: Synthetic and
Mechanistic Studies, Adv. Synth. Catal. 2009, 351, 3207−3216; (b)
Deal, E. L.; Petit, C.; Montchamp, J. L. Palladium-Catalyzed
Cross-Coupling of H-Phosphinate Esters with Chloroarenes, Org. Lett.
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perature, Palladium-Mediated P-Arylation of Secondary Phosphine
Oxides, Org. Lett. 2012, 14, 4370−4373.
Conclusions
In conclusion, we have revealed that some 4-hydroxy-picolinic
acid derived amides are more efficient ligands for Cu-catalyzed
coupling of (hetero)aryl halides with secondary phosphine oxides
and phosphites, which allowed the coupling with a number of
(hetero)aryl bromides and iodides complete at relatively low cat-
alytic loadings. This method has been used for conveniently as-
sembling (S)-t-BuPHOX, and may find more applications in pre-
paring other phosphine ligands and synthetically useful aryl
phosphonates.[16]
Kalek, M.; Ziadi, A.; Stawnski, J. Microwave-Assisted Palladi-
um-Catalyzed Cross-Coupling of Aryl and Vinyl Halides with
H-Phosphonate Diesters, Org. Lett. 2008, 10, 4637−4640.
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Microwave-Promoted Palladium(II)-Catalyzed C-P Bond Formation by
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Experimental
General procedure for the Cu-catalyzed phosphorylation of
aryl bromide. The (hetero)aryl bromide (1.0 mmol), phosphine
oxides (1.1 mmol) (or phosphites (1.5 mmol)), CuI (9.5 mg , 0.05
mmol), L6 (13.9 mg , 0.05 mmol) and K2CO3 (207.3 mg, 1.5 mmol)
(or Na2CO3 (159.0 mg, 1.5 mmol)) were placed into a Schlenk tube
(10 mL) with a magnetic stir bar. The reaction vessel was evacu-
ated and backfilled with argon three times, then i-PrOH (1 mL)
was added under a positive argon pressure (Note: for liquid sub-
strates, they were added after the tube was backfilled with argon).
The reaction mixture was heated at 120 oC for 20 h under vigorous
stirring. The cooled solution was diluted with ethyl acetate and
washed with brine. The organic phase was dried over Na2SO4,
concentrated in vacuo, and purified by silica gel flash chromatog-
raphy to afford the corresponding arylphosphine oxides or ar-
ylphosphonates.
General procedure for the Cu-catalyzed phosphorylation of
aryl bromide. The (hetero)aryl iodides (2.0 mmol), phosphine
oxides (2.2 mmol), CuI (11.4 mg, 0.06 mmol), L7 (15.5 mg, 0.06
mmol) and K2CO3 (414.6 mg, 3.0 mmol) were placed into a Schlenk
tube (20 mL) with a magnetic stir bar. The reaction vessel was
evacuated and backfilled with argon three times, then i-PrOH (2
mL) was added under a positive argon pressure (Note: for liquid
substrates, they were added after the tube was backfilled with
argon). The reaction mixture was heated at 120 oC for 10 h under
vigorous stirring. The cooled solution was diluted with ethyl ace-
tate and washed with brine. The organic phase was dried over
Na2SO4, concentrated in vacuo, and purified by silica gel flash
chromatography to afford the corresponding arylphosphine ox-
ides.
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(The following will be filled in by the editorial staff)
Manuscript received: XXXX, 2021
Manuscript revised: XXXX, 2021
Manuscript accepted: XXXX, 2021
Accepted manuscript online: XXXX, 2021
Version of record online: XXXX, 2021
Chin. J. Chem. 2021, 39, XXX－XXX
© 2021 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
www.cjc.wiley-vch.de

First author et al.
Report
Entry for the Table of Contents
Cu/Picolinamides-Catalyzed Coupling of (Hetero)aryl Halides with Secondary Phosphine Oxides and Phosphite
Chao Fang,a Bangguo Wei,*,a and Dawei Ma*,b
Chin. J. Chem. 2021, 39, XXX—XXX. DOI: 10.1002/cjoc.202100XXX
O
P
CuI,
R
ligand
i-PrOH
X
O
P
R
=
=
=
mol
CuI &
L6
20 h
,
L7
10 h
,
X
X
R
Br, 5
mol
K
2CO3,
120 o
+
3
het
% CuI &
and
H
R
I,
aryl
R
het
OH
C
isopropoxyl
Y
Y
OH
Me
H
H
N
N
N
N
O
Me
O
L6
L7
Me
OH
Text for Table of Contents.
www.cjc.wiley-vch.de
© 2021 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
Chin. J. Chem. 2021, 39, XXX－XXX