Rhodium(II)-Catalyzed Aryl C?H Carboxylation of 2-Pyridylphenols with CO2

Article abstract of DOI:10.1002/adsc.201800611

A protocol for C?H carboxylation of electron-deficient 2-pyridylphenols with CO₂ through a Rh(II)-catalyzed C?H bond activation under redox-neutral conditions has been developed. A suitable phosphine ligand was crucial for this reaction. This m

Full text of DOI:10.1002/adsc.201800611

Title: Rhodium(II)-Catalyzed Aryl C–H Carboxylation of 2-
Pyridylphenols with CO2
Authors: Zhihua Cai, Shangda Li, Yuzhen Gao, and Gang Li
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Adv. Synth. Catal. 10.1002/adsc.201800611
Link to VoR: http://dx.doi.org/10.1002/adsc.201800611

10.1002/adsc.201800611
Advanced Synthesis & Catalysis
UPDATE
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Rhodium(II)-Catalyzed Aryl C–H Carboxylation of 2-
Pyridylphenols with CO2
Zhihua Cai,a,b Shangda Li,a Yuzhen Gao,a and Gang Lia,b*
aState Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research
on the Structure of Matter, Fuzhou, Fujian 350002, China.
Phone and fax: (+86)-591-63173547; e-mail: gangli@fjirsm.ac.cn
bUniversity of Chinese Academy of Science, Beijing, 100049, China.
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.
Abstract. A protocol for C–H carboxylation of electron- -ns that are key structural motifs in biologically important
deficient 2-pyridylphenols with CO2 through a Rh(II)- molecules. Facile product derivatizations were also
catalyzed C–H bond activation under redox-neutral exemplified.
conditions has been developed. A suitable phosphine ligand
was crucial for this reaction. This method provided, in
generally high yields, an access to a class of pyrido-coumari
Keywords: carbon dioxide fixation; carboxylation; C-H
activation; rhodium; ligand promotion
Fine chemicals synthesis via fixation of carbon
dioxide (CO2), an abundant, renewable, low-cost,
non-toxic and green C1 feedstock, is highly
attractive.[1] This type of transformation is, however,
often challenging as CO2 is thermodynamically and
kinetically stable. Therefore, direct carboxylation of
aromatic compounds with CO2 for the synthesis of
(hetero)aromatic carboxylic acids or their derivatives
through transition-metal-catalyzed C–H activation is
very limited.[2] In 2010, the group of Nolan reported a
breakthrough of carboxylation of moderately acidic
sp2 C–H bonds of arenes enabled by a gold complex
[(NHC)AuOH] under basic conditions.[3] Shortly after,
Hou and co-workers, as well as the Nolan and Cazin
with CO2 through a Rh(II)-catalyzed C–H bond
activation under redox-neutral conditions, which
group
transformation but with Cu(I)-NHC complexes as the
catalysts simultaneously (Scheme
1a).[4-5]
independently
reported
a
similar
Remarkably, the carboxylation of much less-acidic
aryl C–H bond with CO2 was achieved by Iwasawa
and co-workers (Scheme 1b). The reaction proceeded
via
a
Rh(I)/Rh(III) catalytic cycle, and
a
stoichiometric pyrophoric methylating reagent
AlMe2OMe was the key for an efficient
carboxylation.[6-7] Importantly, the same group
demonstrated later that simple arenes could also be
carboxylated with this method.[6b,c] Moreover,
carboxylation of alkenyl C–H bonds, whose reactivity
are different from aryl C–H bonds, was also realized
by the Iwasawa group using a phenolic hydroxyl
group as the chelating group with Pd(II) (Scheme
1c).[8a] This transformation was also achieved by Yu
and Zhi under transition-metal-free conditions in
lower yields, whose reaction conditions were better
compatible with compounds containing an
imidazo[1,2-a]pyridine scaffold (Scheme 1c).[8b]
Most recently, our group developed a site-selective
and efficient carboxylation of 2-(hetero)arylphenols
Scheme 1. Transition-metal-catalyzed carboxylation of
aryl and alkenyl C–H bonds with CO2.
1
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800611
Advanced Synthesis & Catalysis
Table 1. Optimization of reaction conditions[a]
Herein, we report a ligand promoted, Rh(II)-
catalyzed C–H carboxylation of 2-pyridylphenols
through CO2 fixation for the synthesis of a class of
pyrido-coumarin derivatives, a motif found in
biologically active compounds.[10-14]
To start our investigation, 2-(pyridin-4-yl)phenol
1a was selected as the model substrate. Although 1a
has been proved to be able to afford the desired
product 2a as a single example in our previous report
with ligand L2 (Table 1 entry 1),[9] we attempted to
find the optimal reaction conditions for this class of
substrate by evaluating the ligands first. Gratifyingly,
MePhos (L1) was proved to be the best new
phosphine ligand after examining a series of mono-
and di-phosphine ligands (see also Supporting
Information (SI) for more reaction conditions
Entry Ligand
Base
Temp (°C)
2a (%)
1
2
3
4
5
6[c]
7
8
9
10
11[d]
12[e]
13[f]
14
15[f]
16
17
18[h]
19[i]
20[j]
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuONa
Cs2CO3
t-BuOK
t-BuOK
t-BuOK
100
100
100
100
100
150
120
110
90
72
75 (74)[b]
40
41
60
75 (73)[b]
70
69
L2
L1
L3
L4
L5
L6
L1
L1
L1
L1
L1
L1
L1
-
Table 2. Substrate scope[a]
69
43
23
3
1
3
80
100
100
100
100
100
100
100
100
100
100
(2a1, 52)[g]
-
L1
L1
L1
L1
73
4
15
66
0
L1
[a]Reaction conditions: 1a (0.1 mmol), CO2 (1 atm, closed),
[Rh(OAc)2]2 (5 mol%), ligand (10 mol%), base (4.5 equiv),
1
DMF (1 mL), 24 h. Yield was determined by H NMR
with CH2Br2 as internal standard; 1a and other side
products including 2a1 might exist for some reactions but
they would be dissolved in the water phase during work-up
and were not detected. [b]Isolated yield in parenthesis. [c]10
h. [d]DMA. [e]diglyme. [f]No [Rh(OAc)2]2. [g]Isolated yield
1
of 2a1 and 48% of 1a was also found in the crude H
NMR; 2a1 was obtained by treating the reaction with
SOCl2 in MeOH during reaction work-up, see SI for
detailed procedure. [h][Rh(Cp*)Cl2]2 was used instead of
[Rh(OAc)2]2. [i][Rh(OAc)2]2 (2.5 mol%), L1 (5 mol%), 48
h. [j]CO (1 atm, closed) was used instead of CO2. DPPP:
1,3-bis(diphenylphosphino)propane;
pentamethylcyclopentadienyl.
Cp*:
mainly focused on electron-neutral 2-phenylphenols
and electron-rich substrates with a five-membered
heterocycle (Scheme 1d).[9] And only an isolated
example of 2-pyridylphenol was exemplified in this
report. To further explore this strategy, we tried to
developed better reaction conditions for more 2-
pyridylphenols that possess an electron-deficient
pyridyl group, which might be challenging due to the
competing Kolbe-Schmitt type of reaction that could
occur to the electron-rich phenolic ring (Scheme 1).
[a]Reaction conditions: 1 (0.1 mmol), CO2 (1 atm, closed),
[Rh(OAc)2]2 (5 mol%), MePhos (10 mol%), t-BuOK (4.5
equiv), DMF (1 mL), 100 °C, 24 h; isolated yield. Minor
Kolbe-Schmitt type side product might be formed for some
substrates. [b][Rh(OAc)2]2 (2.5 mol%), MePhos (5 mol%),
100 °C. [c]48 h. [d]IMes·HCl (10 mol%), 150 °C, 24 h.
[e]About 5% of isomer of carboxylation at the ortho-
position of nitrogen atom was also detected but not isolated.
[f]10 h. [g]100 °C, 72 h.
2
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800611
Advanced Synthesis & Catalysis
screening), leading to 74% of isolated yield of 2a
with 5 mol% [Rh(OAc)2]2 and 4.5 equiv of t-BuOK
in DMF at 100 °C for 24 h under atmospheric
pressure of CO2 (Table 1, entries 2-5). N-heterocyclic
carbene (NHC) ligands were also tested, and the
IMes·HCl (L6) delivered a comparable yield of 2a as
MePhos in 10 h, but at a high temperature of 150 °C
and lower yield would be obtained in a longer time
(entry 6). After screening the reaction temperature
solvents like N,N-dimethylacetamide could also lead
to the desired prouct (see SI), it was concluded that
DMF, which might decompose to generate CO and is
the most likely carboxylic source except CO2, was
not likely the carboxylic source for this reaction.
With the optimized conditions in hand, we
explored the scope of this reaction with substituted 2-
(pyridin-4-yl)phenols and 2-(pyridin-3-yl)phenols,
leading to a class of pyrido-coumarin derivatives in
generally good to excellent yields (Scheme 2).
Substrates with one or two methyl substituents on the
phenolic ring reacted efficiently to give the desired
products (2b-2f) in good yields, which also indicated
that the number and the position of the methyl
substituent on the aromatic ring exerted a small
influence on the reaction. Since the substrates with
substituents at the para-position of the hydroxyl of
the phenolic ring was readily available, several para-
substituted substrates with other alkyl substituents
were also investigated and they were well tolerated
(2g-2j). It is worth mentioning that products 2g-2i
could still be obtained in high yields with a lower
loading of [Rh(OAc)2]2 (2.5 mol%), albeit in a longer
reaction time. Subsequently, substrates bearing
electron-donating methoxyl and electron-withdrawing
groups such as fluoro and phenyl groups were also
smoothly converted to the desired products (2k-2n).
Notably, acetal 1o was compatible with this reaction,
albeit in a modest yield, enabling further elaborations
at this position (2o). Interestingly, a carbon-carbon
double bond transfer occurred when 4-allyl-2-
(pyridin-4-yl)phenol 1p was employed as the
substrate, affording a propenyl product 2p. However,
a hindered methyl substitution on the phenol ring was
not well tolerated (2q). Moreover, a hindered methyl
substitution on the pyridin-4-yl ring could not be
tolerated (2r). And a fluorine at the ortho-position of
nitrogen atom led to no product with partial
o
carefully, it was revealed that 100 C was still the
best choice with MePhos as the ligand (entries 7-10).
Notably, the choice of solvent was important in this
reaction as other solvents such as DMA and diglyme
led to much lower yield than DMF (entries 11 and
12). The reaction was almost shut down in the
absence of a rhodium catalyst or the ligand (entries
13-15), and side product 2a1 would be produced from
the well-known Kolbe-Schmitt type of reaction under
basic conditions (entry 15) by treating the reaction
with SOCl2 in MeOH during reaction work-up.
Interestingly, the carboxylation at the ortho-position
of phenolic hydroxyl group carboxylation was not
observed, which might result from the use of
potassium base, since the potassium cation could
promote the formation of para-carboxylated products
under basic conditions.[2a] However, by using the
above work-up method only trace of (about 2%) 2a1
was detected under the best reaction conditions in
entry 2. The effect of base was also examined and t-
BuOK was found to be the most suitable one
(entries16 and 17). Moreover, other Rh-catalysts such
as [Rh(Cp*)Cl2]2 were also employed, but the
reaction was almost inhibited (entry 18). In addition,
good yield of 2a could also be generated in 48 h
when the loading of [Rh(OAc)2]2 was decreased to
2.5 mol% (entry 19). Finally, to test the carboxylic
source,[11i] CO2 was replaced with CO and not any
desired product was obtained (entry 20). Since other
Scheme 2. Synthetic elaborations of carboxylated product 2a.
3
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800611
Advanced Synthesis & Catalysis
decomposition of the substrate (2s). Pleasingly,
reactions of substrates with a methyl or methoxyl
group at the ortho-position of nitrogen atom on the
pyridin-4-yl ring could afford good yields of desired
products (2t and 2u). Subsequently, 2-(pyridin-3-
yl)phenols were examined and the desired products
could be obtained with high regio-selectivity using
IMes·HCl as the ligand (2v-2x), although a higher
temperature (2v and 2w) or a longer reaction time
(2x) was necessary. Unfortunately, quinoline and
isoquinoline derivatives only led to very low yields of
desired products (2y and 2z).
The utility of this methodology was demonstrated
by further elaboration of the pyrido-coumarin
product 2a (Scheme 3). Firstly, the C–H
carboxylation reaction of 1a could be easily scaled
up to a 7.5 mmol scale with the model substrate 1a,
affording 2a (1.09 g) in 74% yield. Treatment of 2a
with BF3·Et2O/NaBH4 or DIBAL-H gave the
corresponding reduced product 2aa and 2ab in 74%
and 80% yields, respectively. Furthermore, triflate
2ad was produced in 90% yield from 2ac, which was
prepared from 2a with LiHMDS and Bn2NH, by
triflation of the hydroxyl group. Triflate 2ad was
then transformed to a range of synthetically useful
substances with well-established coupling reactions
such as cyanation (2ae), arylation (2af) and
alkenylation (2ag) in good yields, demonstrating the
versatility of the synthetic elaborations of this
method.
situ, leading to complex B. C–H bond activation of B
via a proton abstraction process with the assistance of
an external base ROK (such as t-BuOK and t-
BuOCO2K) affords the metallacycle C. C can be
transformed back to B by protonolysis reversibly.
Nucleophilic carboxylation of C with CO2 affords the
rhodium carboxylate complex D. Nucleophilic
carboxylation might be reversible and reproduce C.
The eight-membered complex D, which might be
unstable, can be converted to complex E by ligand
exchange with KOAc. Another ligand exchange of
rhodium carboxylate E with KOAc and subsequent
protonolysis of the resulting carboxylate, followed by
a lactonization, would generate the desired product
2a and complex A as well. The lactonization should
be fast and the stability of the lactonization product
2a might be the key for the shift of the
carboxylation−decarboxylation equilibrium to the
product side. It should also be noted other catalytic
cycles such as that involves other valent Rh species
cannot be ruled out completely at present.
Figure 1. Ortep drawing of the asymmetric unit the crystal
structure of complex 3 at 30% probability level.[15]
To gain more insights into the reaction mechanism,
we obtained the potential active catalyst Rh(II)
complex
3
(Fig. 1), whose structure was
characterized by X-ray crystallography. Similar yield
of desired product 2a could be produced with 5
mol% of complex 3 with another 5 mol% of the
ligand MePhos (L1), which implied that a total of 10
mol% of the ligand was required in this reaction (see
SI). 13CO2 was also utilized to confirm the carboxylic
source [Eq. (1)], and the 13C NMR as well as the
high-resolution mass spectrometry clearly indicated
that CO2 was the carboxylic source (see SI).[11i]
Based on the above investigations as well as our
previous study,[8] the proposed tentative catalytic
cycle is depicted in Fig. 2. First, deprotonation of 1a
with t-BuOK would generate the salt 1a', which
would coordinate with complex A that is formed in
Figure 2. Tentative catalytic cycle.
In conclusion, we have developed an efficient
Rh(II)-catalyzed C–H carboxylation of 2-
pyridylphenols with CO2 under redox-neutral
4
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800611
Advanced Synthesis & Catalysis
conditions. This novel method was compatible with
challenging electron-deficient pyrido-heterocycles,
leading to generally high yields of a series of pyrido-
coumarins that are key structural motifs in
X. Lü, Chin. J. Org. Chem. 2017, 37, 1309; o) Z.
Zhang, T. Ju, J.-H. Ye, D.-G. Yu, Synlett 2017, 28,
741; p) G. Yuan, C. Qi, W. Wu, H. Jiang, Curr. Opin.
Green Sustainable Chem. 2017, 3, 22; q) A. Tortajada,
F. Juliá-Hernández, M. Börjesson, T. Moragas, R.
biologically
important
molecules.
Product
derivatizations may also provide a short-cut to access
to a new class of pyrido-heterocycles.
Martin,
Angew.
Chem.
2018,
DOI:
10.1002/ange.201803186; Angew. Chem. Int. Ed.
10.1002/anie.201803186.
[2] a) A. S. Lindsey, H. Jeskey, Chem. Rev. 1957, 57, 583;
b) D. M. Dalton, T. Rovis, Nat. chem. 2010, 2, 710; c) I.
I. F. Boogaerts, S. P. Nolan, Chem. Commun. 2011, 47,
3021; d) L. Ackermann, Angew. Chem. 2011, 123,
3926; Angew. Chem. Int. Ed. 2011, 50, 3842; e) Y.
Tsuji, T. Fujihara, Chem. Commun. 2012, 48, 9956; f)
L. Zhang, Z. Hou, Chem. Sci. 2013, 4, 3395; g) M. Brill,
F. Lazreg, C. S. J. Cazin, S. P. Nolan, Top. Organomet.
Chem. 2015, 53, 225; h) J. Luo, I. Larrosa,
ChemSusChem 2017, 10, 3317; i) Y.-Y. Gui, W.-J.
Zhou, J.-H. Ye, D.-G. Yu, ChemSusChem 2017, 10,
1337.
Experimental Section
General Procedure for Carboxylation of 2-
Pyridylphenols 1 with CO2: In a glove box, to an oven-
dried 50 mL Schlenk sealed tube (with a Teflon cap)
equipped with a magnetic stir bar was added 1 (0.1 mmol),
Rh2(OAc)4 (2.5-5 mol %), ligand (5-10 mol %, MePhos or
IMes·HCl) and t-BuOK (50 mg, 0.45 mmol) (Note: t-
BuOK should be dry). After taken out of the glove box, the
tube was evacuated under vacuum and charged with CO2
(1 atm, × 3). Then anhydrous solvent (1.0 mL) was added
along the inside wall of the tube loaded with CO2.
Afterwards, the reaction tube was evacuated briefly under
vacuum and charged with CO2 (1 atm, × 3). The tube was
capped and then placed into a preheated hotplate (100 or
[3] I. I. F. Boogaerts, S. P. Nolan, J. Am. Chem. Soc. 2010,
132, 8858.
o
150 C). The reaction was stirred vigorously (Note: good
stirring is important!) for 12-48 h and cooled to room
temperature. The reaction was diluted with EtOAc (20 mL)
and filtered through a short pad of Celite. The tube and
Celite pad were washed with an additional 10 mL of
EtOAc. The filtrate was concentrated in vacuo, and
purified by flash silica gel chromatography or preparative
thin layer chromatography using petroleum ether/EtOAc
(3/1) as the eluent to afford the desired product.
[4] a) L. Zhang, J. Cheng, T. Ohishi, Z. Hou, Angew. Chem.
2010, 122, 8852; Angew. Chem. Int. Ed. 2010, 49, 8670;
b) H. Inomata, K. Ogata, S. I. Fukuzawa, Z. Hou, Org.
Lett. 2012, 14, 3986.
[5] I. I. F. Boogaerts, G. C. Fortman, M. R. L. Furst, C. S. J.
Cazin, S. P. Nolan, Angew. Chem. 2010, 122, 8856;
Angew. Chem. Int. Ed. 2010, 49, 8674.
[6] a) H. Mizuno, J. Takaya, N. Iwasawa, J. Am. Chem.
Soc. 2011, 133, 1251; b) T. Suga, H. Mizuno, J. Takaya,
N. Iwasawa, Chem. Commun. 2014, 50, 14360; c) T.
Suga, T. Saitou, J. Takaya, N. Iwasawa, Chem. Sci.
2017, 8, 1454.
Acknowledgements
We gratefully thank the financial supports from NSFC (Grant No.
21702206, 21402198), the Natural Science Foundation of Fujian
Province (2017J06007, 2017J05038), the Strategic Priority
Research Program of the Chinese Academy of Sciences (Grant
No. XDB20000000). Y. Gao also thanks the National
Postdoctoral Program for Innovative Talents (BX201700244)
and China Postdoctoral Science Foundation (2017M622087).
[7] During the revision of our manuscript, the following
reports of Pd-catalyzed C–H carboxylation of arenes
with CO2 were published: a) L. Song, L. Zhu, Z. Zhang,
J.-H. Ye, S.-S. Yan, J.-L. Han, Z.-B. Yin, Y. Lan, D.-G.
Yu, Org. Lett. 2018, 20, 3776; b) L. Song, G.-M. Cao,
W.-J. Zhou, J.-H. Ye, Z. Zhang, X.-Y. Tian, J. Li, D.-G.
Yu, Org. Chem. Front. 2018, 5, 2086.
References
[1] a) P. Braunstein, D. Matt, D. Nobel, Chem. Rev. 1988,
88, 747. b) T. Sakakura, J.-C. Choi, H. Yasuda, Chem.
Rev. 2007, 107, 2365. c) A. Correa, R. Martín, Angew.
Chem. 2009, 121, 6317; Angew. Chem., Int. Ed. 2009,
48, 6201; d) K. Huang, C.-L. Sun, Z.-J. Shi, Chem. Soc.
Rev. 2011, 40, 2435; e) F. Manjolinho, M. Arndt, K.
Gooßen, L. J. Gooßen, ACS Catal. 2012, 2, 2014; f) M.
He, Y. Sun, B. Han, Angew. Chem. 2013, 125, 9798;
Angew. Chem. Int. Ed. 2013, 52, 9620; g) M. Aresta, A.
Dibenedetto, A. Angelini, Chem. Rev. 2014, 114, 1709;
h) B. Yu, L.-N. He, ChemSusChem 2015, 8, 52; i) Q.
Liu, L. Wu, R. Jackstell, M. Beller, Nat. Commun.
2015, 6, 5933; j) C. Martín, G. Fiorani, A. W. Kleij,
ACS Catal. 2015, 5, 1353; k) M. Börjesson, T. Moragas,
D. Gallego, R. Martin, ACS Catal. 2016, 6, 6739; l) S.
Wang, G. Du, C. Xi, Org. Biomol. Chem. 2016, 14,
3666; m) Q.-W. Song, Z.-H. Zhou, L.-N. He, Green
Chem. 2017, 19, 3707; n) W. Zhang, N. Zhang, C. Guo,
[8] a) K. Sasano, J. Takaya, N. Iwasawa, J. Am. Chem. Soc.
2013, 135, 10954; b) Z. Zhang, T. Ju, M. Miao, J.-L.
Han, Y.-H. Zhang, X.-Y. Zhu, J.-H. Ye, D.-G. Yu, Y.-
G. Zhi, Org. Lett. 2017, 19, 396.
[9] L. Fu, S. Li, Z. Cai, Y. Ding, X.-Q. Guo, L.-P. Zhou, D.
Yuan, Q.-F. Sun, G. Li, Nat. Catal. 2018, 1, 469.
[10] a) D. Wilson, A. P. Termin, L. T. D. Fanning, P.
Krenitsky, P. Joshi, WO 2006/119390 A1, 2006; b) T.
Koike, M. Yoshikawa, H. Ando, W. J. Farnaby, S.
Ikeda, Y. Kajita, T. Nishi, US 2016/0024049 A1, 2016;
c) M. L. Quan, Z. Hu, C. Wang, S. Patil, WO
2015/002915 A1, 2015.
[11] Selected examples of C–H carboxylation with CO2: a)
H. Sugimoto, I. Kawata, H. Taniguchi, Y. Fujiwara, J.
Organomet. Chem. 1984, 266, c44; b) G. A. Olah, B.
Török, J. P. Joschek, I. Bucsi, P. M. Esteves, G. Rasul,
5
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800611
Advanced Synthesis & Catalysis
G. Surya Prakash, J. Am. Chem. Soc. 2002, 124, 11379;
Angew. Chem. Int. Ed. 2015, 54, 3084; o) L. Zhang, Z.
Han, X. Zhao, Z. Wang, K. Ding, Angew. Chem. Int.
Ed. 2015, 127, 6284; Angew. Chem. Int. Ed. 2015, 54,
6186; p) B. Yu, J.-N. Xie, C.-L. Zhong, W. Li, L.-N.
He, ACS Catal. 2015, 5, 3940; q) Q. Qian, M. Cui, Z.
He, C. Wu, Q. Zhu, Z. Zhang, J. Ma, G. Yang, J. Zhang,
B. Han, Chem. Sci. 2015, 6, 5685; r) W.-Z. Zhang, M.-
W. Yang, X.-T. Yang, L.-L. Shi, H.-B. Wang, X.-B. Lu,
Org. Chem. Front. 2016, 3, 217; s) S. Sun, W. M. Hu,
N. Gu, J. Cheng, Chem. Eur. J. 2016, 22, 18729; t) K.
Shimomaki, K. Murata, R. Martin, N. Iwasawa, J. Am.
Chem. Soc. 2017, 139, 9467; u) Q.-Y. Meng, S. Wang,
B. Konig, Angew. Chem. 2017, 129, 13611; Angew.
Chem. Int. Ed. 2017, 56, 13426; v) Y.-Y. Gui, N. Hu,
X.-W. Chen, L.-L. Liao, T. Ju, J.-H. Ye, Z. Zhang, J. Li,
D.-G. Yu, J. Am. Chem. Soc. 2017, 139, 17011; w) W.-
Z. Zhang, N. Zhang, Y.-Q. Sun, Y.-W. Ding, X.-B. Lu,
ACS Catal. 2017, 7, 8072; x) W. Xiong, C. Qi, T. Guo,
M. Zhang, K. Chen, H. Jiang, Green Chem. 2017, 19,
1642.
c) K. Nemoto, H. Yoshida, N. Egusa, N. Morohashi, T.
Hattori, J. Org. Chem. 2010, 75, 7855; d) D. Yu, Y.
Zhang, Proc. Natl. Acad. Sci. 2010, 107, 20184; e) L. J.
Gooßen, N. Rodríguez, F. Manjolinho, P. P. Lange,
Adv. Synth. Catal. 2010, 352, 2913; f) W.-Z. Zhang,
W.-J. Li, X. Zhang, H. Zhou, X.-B. Lu, Org. Lett. 2010,
12, 4748; g) O. Vechorkin, N. Hirt, X. Hu, Org. Lett.
2010, 12, 3567; h) W.-J. Yoo, M. G. Capdevila, X. Du,
S. Kobayashi, Org. Lett. 2012, 14, 5326; i) C.-X. Guo,
B. Yu, J.-N. Xie, L.-N. He, Green Chem. 2015, 17, 474.
j) Y. Masuda, N. Ishida, M. Murakami, J. Am. Chem.
Soc. 2015, 137, 14063; k) W.-Z. Zhang, M.-W. Yang,
X.-B. Lu, Green Chem. 2016, 18, 4181; l) Z. Zhang,
L.-L. Liao, S.-S. Yan, L. Wang, Y.-Q. He, J.-H. Ye, J.
Li, Y.-G. Zhi, D.-G. Yu, Angew. Chem. 2016, 128,
7184; Angew. Chem. Int. Ed. 2016, 55, 7068; m) J. Luo,
S. Preciado, P. Xie, I. Larrosa, Chem. Eur. J. 2016, 22,
6798; n) S. Wang, P. Shao, G. Du, C. Xi, J. Org. Chem.
2016, 81, 6672; o) A. Banerjee, G. R. Dick, T. Yoshino,
M. W. Kanan, Nature 2016, 531, 215; p) S. Fenner, L.
Ackermann, Green Chem. 2016, 18, 3804; q) N. Ishida,
Y. Masuda, S. Uemoto, M. Murakami, Chem. Eur. J.
2016, 22, 6524; r) F. Julia-Hernandez, T. Moragas, J.
Cornella, R. Martin, Nature 2017, 545, 84; s) H. Seo,
M. H. Katcher, T. F. Jamison, Nat. chem. 2017, 9, 453;
t) K. Michigami, T. Mita, Y. Sato, J. Am. Chem. Soc.
2017, 139, 6094.
[13] For Rh-catalyzed C–H activation: a) P. Albano, M.
Aresta, M. Manassero, Inorg. Chem. 1980, 19, 1069;
b) M. Kim, J. Kwak, S. Chang, Angew. Chem. 2009,
121, 9097; Angew. Chem. Int. Ed. 2009, 48, 8935; c)
F. W. W.-D. Patureau, J.; Glorius, F., Aldrichimica
Acta 2012, 45, 31; d) G. Song, F. Wang, X. Li, Chem.
Soc. Rev. 2012, 41, 3651; e) N. Kuhl, N. Schröder, F.
Glorius, Adv. Synth. Catal. 2014, 356, 1443; f) G.
Song, X. Li, Acc. Chem. Res. 2015, 48, 1007; g) B.
Ye, N. Cramer, Acc. Chem. Res. 2015, 48, 1308; h) Y.
Yang, K. Li, Y. Cheng, D. Wan, M. Li, J. You, Chem.
Commun. 2016, 52, 2872; i) S.-S. Li, L. Qin, L. Dong,
Org. Biomol. Chem. 2016, 14, 4554; j) X. Qi, Y. Li, R.
Bai, Y. Lan, Acc. Chem. Res. 2017, 50, 2799.
[12] Selected examples of CO2 fixation for small molecule
synthesis: a) K. Ukai, M. Aoki, J. Takaya, N. Iwasawa,
J. Am. Chem. Soc. 2006, 128, 8706; b) T. Ohishi, M.
Nishiura, Z. Hou, Angew. Chem. Int. Ed. 2008, 120,
5876; Angew. Chem. Int. Ed. 2008, 47, 5792; c) C. S.
Yeung, V. M. Dong, J. Am. Chem. Soc. 2008, 130,
7826; d) C. M. Williams, J. B. Johnson, T. Rovis, J. Am.
Chem. Soc. 2008, 130, 14936; e) A. Correa, R. Martin,
J. Am. Chem. Soc. 2009, 131, 15974; f) S. Li, W. Yuan,
S. Ma, Angew. Chem. 2011, 123, 2626; Angew. Chem.
Int. Ed. 2011, 50, 2578; g) T. Fujihara, K. Nogi, T. Xu,
J. Terao, Y. Tsuji, J. Am. Chem. Soc. 2012, 134, 9106;
h) X. Zhang, W.-Z. Zhang, L.-L. Shi, C.-X. Guo, L.-L.
Zhang, X.-B. Lu, Chem. Commun. 2012, 48, 6292; i) B.
Yu, Z.-F. Diao, C.-X. Guo, C.-L. Zhong, L.-N. He, Y.-
N. Zhao, Q.-W. Song, A.-H. Liu, J.-Q. Wang, Green
Chem. 2013, 15, 2401; j) H. Tran-Vu, O. Daugulis,
ACS Catal 2013, 3, 2417; k) Y. Li, T. Yan, K. Junge,
M. Beller, Angew. Chem. 2014, 126, 10644; Angew.
Chem. Int. Ed. 2014, 53, 10476; l) A. Ueno, M.
Takimoto, W. W. O, M. Nishiura, T. Ikariya, Z. Hou,
Chem. Asian J. 2015, 10, 1010; m) W. Xiong, C. Qi, Y.
Peng, T. Guo, M. Zhang, H. Jiang, Chem. Eur. J. 2015,
21, 14314; n) Xiong, W.; Qi, C.; He, H.; Ouyang, L.;
Zhang, M.; Jiang, H. Angew. Chem. 2015, 127, 3127;
[14] For lactonization via C–H activation: a) X.-F. Wu, H.
Neumann, M. Beller, Chem. Rev. 2013, 113, 1; b) B.
Liu, F. Hu, B.-F. Shi, ACS Catal. 2015, 5, 1863; c) Y.
Lu, D. Leow, X. Wang, K. M. Engle, J.-Q. Yu,
Chem.Sci. 2011, 2, 967; d) S. Luo, F. X. Luo, X.-S.
Zhang, Z.-J. Shi, Angew. Chem. 2013, 125, 10792;
Angew. Chem. Int. Ed. 2013, 52, 10598; e) T.-H. Lee,
J. Jayakumar, C.-H. Cheng, S.-C. Chuang, Chem.
Commun. 2013, 49, 11797; f) K. Inamoto, J.
Kadokawa, Y. Kondo, Org. Lett. 2013, 15, 3962.
[15] CCDC-1819284 contains the supplementary
crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge
Crystallographic
Data
Centre
via
www.ccdc.cam.ac.uk/data_request/cif.
6
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800611
Advanced Synthesis & Catalysis
UPDATE
Rhodium(II)-Catalyzed Aryl C–H Carboxylation of
2-Pyridylphenols with CO2
Adv. Synth. Catal. Year, Volume, Page – Page
Zhihua Cai,a,b Shangda Li,a Yuzhen Gao,a and Gang
Lia,b*
7
This article is protected by copyright. All rights reserved.