Rhodium-Catalyzed meta-Selective C?H Carboxylation Reaction of 1,1-Diarylethylenes via Hydrorhodation-Rhodium Migration

Article abstract of DOI:10.1002/anie.202109470

A meta-selective C?H carboxylation reaction of 1,1-diarylethylene derivatives with CO₂ by using a rhodium catalyst with NaOⁱPr as a stoichiometric reductant has been achieved. Together with hydrogenation of the ethylene moiety, a carboxyl group was introduced to the meta-position of the aryl ring with high selectivity over the ortho-positions. Experimental and computational mechanistic studies indicate that this carboxylation reaction proceeds via hydrorhodation on the ethylene moiety, followed by 1,4-rhodium migration and successive 1,2-rhodium migration on the aryl ring. The use of a bulky phosphine ligand seems to be the key to this unusual aryl-to-aryl 1,2-rhodium shift.

Full text of DOI:10.1002/anie.202109470

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International Edition: doi.org/10.1002/anie.202109470
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Homogeneous Catalysis
À
Rhodium-Catalyzed meta-Selective C H Carboxylation Reaction of
1,1-Diarylethylenes via Hydrorhodation-Rhodium Migration
Takanobu Saito, Joaquim Caner, Naoyuki Toriumi, and Nobuharu Iwasawa*
À
Abstract: A meta-selective C H carboxylation reaction of 1,1-
diarylethylene derivatives with CO2 by using a rhodium
catalyst with NaOiPr as a stoichiometric reductant has been
achieved. Together with hydrogenation of the ethylene moiety,
a carboxyl group was introduced to the meta-position of the
aryl ring with high selectivity over the ortho-positions.
Experimental and computational mechanistic studies indicate
that this carboxylation reaction proceeds via hydrorhodation
on the ethylene moiety, followed by 1,4-rhodium migration and
successive 1,2-rhodium migration on the aryl ring. The use of
a bulky phosphine ligand seems to be the key to this unusual
aryl-to-aryl 1,2-rhodium shift.
Introduction
À
In contrast to the well-established ortho-selective C H
activation of arenes containing a directing group, meta-
À
selective C H activation of arenes remains relatively unex-
plored.[1,2] Several methods for C C bond formation have
À
recently been reported by utilizing characteristic properties of
the transition-metals or by designing suitable ligand systems,
À
such as meta-C H alkenylation assisted by a long and linear
end-on template pioneered by Yu,[3–8] meta-C H alkylation/
À
arylation of arenes by palladium/norbornene cooperative
catalysis by Yu[9,10] and Dong,[11,12] ruthenium-catalyzed meta-
[13,14]
and Ackermann,[15–17]
À
C H functionalization by Frost
which is proposed to proceed via successive single-electron
transfer (SET) from ruthenium and radical addition at the
para-position to the carbon-ruthenium bond,[14,16,17] and so on
(Scheme 1a).
Concerning the direct carboxylation of arenes using CO2,
our group reported ortho-selective carboxylation of 2-phenyl-
pyridine derivatives with a rhodium catalyst and a methyl
aluminum reagent (Scheme 1b).[18] Since then, several groups
À
Scheme 1. meta-Selective C H carboxylation.
À
have been engaged in C H carboxylation of arenes, but
almost all of them deal with ortho-selective carboxylation of
functional groups[19–22] and meta-selective carboxylation re-
actions of arenes have not been reported yet.
tandem 1,4-rhodium shift and unique 1,2-rhodium shift on the
aromatic ring.
Here we report rhodium-catalyzed meta-selective carbox-
ylation of 1,1-diarylethylene derivatives using isopropoxide as Results and Discussion
a reductant (Scheme 1c). This reaction is supposed to proceed
À
via hydrorhodation of the ethylene moiety, followed by
During the investigation of new types of C H carbox-
ylation reactions, we found the reaction of 1,1-diphenyl-
ethylene (1a) with CO2 in nBu2O afforded meta-carboxylated
compound, 3-(1-phenylethyl)benzoic acid (2a), with a turn-
over number (TON) of 13 using catalytic amounts of [RhCl-
(coe)2]2 and 1,1’-bis(diisopropylphosphino)ferrocene (dippf)
in the presence of NaOiPr at 1558C (Table 1, entry 1). As such
[*] T. Saito, Dr. J. Caner, Dr. N. Toriumi, Prof. Dr. N. Iwasawa
Department of Chemistry, Tokyo Institute of Technology
O-okayama, Meguro-ku, Tokyo 152-8551 (Japan)
E-mail: niwasawa@chem.titech.ac.jp
Supporting information and the ORCID identification number(s) for
the author(s) of this article can be found under:
https://doi.org/10.1002/anie.202109470.
À
a meta-selective C H carboxylation reaction was unprece-
dented, we decided to examine this reaction in detail.
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Table 1: Screening of reaction conditions.
Table 2: Substrate scope (TON).
Entry
1
meta/ortho[a]
meta-Carboxylated Product 3
TON of 3[b]
Entry
Conditions
TON (2a/2a’)[a]
92/8
17
1
2
3
4
5
6
7
8
–
13/0.6
0.1/2
0/0
0.6/0
0/0
0/0
8/0
0/0
0/0
4/0
4/0
14/3
18/2
0/0
dcype instead of dippf
Xantphos instead of dippf
NaOMe instead of NaOiPr
NaOEt instead of NaOiPr
LiOiPr instead of NaOiPr
KOiPr instead of NaOiPr
[IrCl(cod)2]2 instead of [RhCl(coe)2]2
DMSO instead of Bu2O
diglyme instead of Bu2O
cyclooctane instead of Bu2O
DEA instead of Bu2O
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
29
2
92/8
5
n
9
n
10
11
12
13
14
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
n
n
closed, 0.5 mL DEA, with 1.1 mmol CsF
without [RhCl(coe)2]2 or CO2
6
3
71/29
[a] Determined by 1H NMR spectroscopy. DEA=N,N-Diethylacetamide.
9
Firstly, optimization of reaction conditions was carried out
(Table 1). Use of 1,2-bis(dicyclohexylphosphino)ethane
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
(dcype), which was the most successful ligand in the
4
97/3
35
[23,24]
À
rhodium-catalyzed direct C H carboxylation of arenes,
gave ortho-benzoic acid 2a’ as the major product (entry 2).
Other bisphosphine ligands such as Xantphos did not afford
2a or 2a’ at all (entry 3 and Table S1), indicating this
carboxylation is very sensitive to ligand structure. While
several bases such as NaOMe, NaOEt, and LiOiPr did not
afford the product, KOiPr gave the meta-carboxylated
product with TON = 8 (entries 4–7). Alkoxides are usually
in equilibrium with corresponding alkoxycarbonates under
a CO2 atmosphere, which decreases their nucleophilicity and
basicity and inhibits the reaction. The superiority of NaOiPr
over NaOMe and NaOEt seems to be due to its larger steric
bulkiness, which relatively disfavors the formation of isopro-
poxycarbonate compared with other alkoxycarbonates.[25] The
reason for the low reactivity with LiOiPr is not clear but could
be related to its lower basicity than that of NaOiPr and KOiPr.
An iridium catalyst was not effective in this reaction (entry 8).
Through the screening of solvents, we found the use of more
polar N,N-diethylacetamide (DEA) gave slightly improved
TON = 14 of 2a while 2a’ was also generated in small TON =
3 (entry 9–12). CsF, which is known to increase the reactivity
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
28
5[c]
94/6
2
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3
6
97/3
5
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
18
À
[26,27]
7[d]
89/11
=
of C O bond by forming FCO2
,
was effective for this
reaction as an additive, and the best TON = 18 of 2a was
obtained using a reduced amount of DEA in a closed reaction
vessel (entry 13). The reaction did not proceed in the absence
of the rhodium catalyst or CO2 (entry 14). Lower temperature
decreased TON of 2a (Table S2).
8
Then the substrate scope was investigated under the
following conditions (Table 2). The reactions were carried out
with 5 mmol of 1,1-diarylethylene, 0.0075 mmol of
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Table 2: (Continued)
suggesting the ortho-fluorine effect was not dominant under
these reaction conditions (entries 3, 5). Less bulky 1-(2-furyl)-
1-phenylethylene (1k) was carboxylated on the ortho-posi-
tion on the furan ring (entry 11). Judging from these results,
both electronic and steric factors are important for the
regioselectivity. Importantly, this meta-carboxylation was also
applicable to 4-fluorostyrene (1l) and 5-ethyl-2-fluoroben-
zoate was afforded with the TON of 23 (entry 12). Polymer-
ization was observed especially for mono-substituted styrene
derivatives under these reaction conditions. Addition of
radical scavengers such as 1,4-dihydroxynaphthalene did not
improve the TONs of the meta-carboxylic acids (Table S5).
Under these reaction conditions, simple hydrogenation of
the ethylene moiety always occurred concurrently. Moreover,
careful analysis of the products revealed that small amounts
of isomeric hydrocarboxylated products on the ethylene
moiety were also obtained (Table 2, entry 1; Scheme 2).
Entry
meta/ortho[a]
meta-Carboxylated Product 3
TON of 3[b]
25
8
93/7
1
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
10
9[c]
>99/1
0
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
16
10[c]
92/8
1
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
11[c]
<1/99
12
À
Scheme 2. Byproducts of meta-selective C H carboxylation. TONs
were determined by 1H NMR spectroscopy.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
12
81/19
23
In the above examination of the generality of the reaction,
substrates were employed in a large excess, actually about
double the amount of the solvent in volume, and the yields of
the products were less than 10% based on the starting
materials (TON = 33 equals to 10% yield). After further
screening of the reaction conditions to reduce the amount of
substrates employed, we have succeeded in obtaining reason-
able yields of the meta-carboxylated products by carrying out
the reaction under the conditions shown in Table 3. Here,
hydrogenated products were obtained as major byproducts,
which led to relatively low yields of the carboxylation
products. For instance, the reaction of 1,1-bis(4-fluorophe-
nyl)ethylene 1d gave the desired product 3d in 52% yield
along with 1,1-bis(4-fluorophenyl)ethane in 23% yield (en-
try 2).
1
[a] Ratio of carboxylic acid 2(meta) to 2’(ortho) determined by H NMR
analysis of the crude mixture before adding TMSCHN2. The ratio was
calculated from the integral of the benzylic proton: except for styrene
derivatives 2l and 2l’, 2 shows a quartet at 4.0–4.7 ppm, while 2’ shows
a quartet at 5.0–5.4 ppm. [b] TON of meta-carboxylated products based
on the weight and their 1H NMR integral of the mixture of several methyl
esters after purification. [c] 0.1 mL of DEA was used. [d] 4.1 mmol of
alkene was used.
[RhCl(coe)2]2, 0.015 mmol of dippf (equimolar to Rh metal),
1.1 mmol of NaOiPr, and 1.1 mmol of CsF in 0.5 mL of DEA
at 1558C for 4 h. To facilitate the purification, the obtained
carboxylic acids were converted to the corresponding methyl
esters by treatment with trimethylsilyldiazomethane
(TMSCHN2).
1,1-Diarylethylenes containing electron-deficient groups
such as fluoro and trifluoromethyl groups were suitable for
this reaction (entries 2–10), and high meta-selectivity and the
TONs of about 10 to more than 30 were achieved in most
cases. In particular, TON of 35 was realized using para-fluoro-
substituted 1,1-diarylethylene 1d. In the case of unsymmet-
rical 1,1-diarylethylenes 1b and 1g–1j, the carboxyl groups
were preferably introduced to the electron-deficient arene
moiety (entries 2, 7–10). Fluoroarenes 1c and 1e were
carboxylated on the meta-positions from the alkyl group,
Considering that ortho-carboxylation, hydrogenation, and
hydrocarboxylation occurred under the carboxylation con-
ditions, hydrorhodation and intramolecular rhodium shift
seemed to be involved in the reaction pathway.[28] To obtain
further insight into the mechanism of this unusual meta-
À
selective C H carboxylation reaction, we performed deute-
rium labeling experiments using ortho- and para-deuterated
1,1-diphenylethylene 1a-d6 and meta-deuterated 1a-d4 as
substrates (Scheme 3). ortho- and para-Deuterated 1a-d6
underwent deuterium transfer from an ortho-position on the
aryl ring to the ethylene moiety in favor of the terminal
carbon (1.08 D) over the internal carbon (0.15 D), forming
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Table 3: Substrate scope (yield).
Table 3: (Continued)
Entry
8[e]
meta/ortho[a]
meta-Carboxylated Product 3
Yield [%][b]
80/20
30
1
[a] Ratio of carboxylic acid 2(meta) to 2’(ortho) determined by H NMR
analysis of the crude mixture before adding TMSCHN2. The ratio was
calculated from the integral of the benzylic proton. [b] Isolated yields of
meta-carboxylated products based on the weight and their 1H NMR
integral of the mixture of several methyl esters after purification.
[c] 1.1 equiv. of NaOiPr was used. [d] nBu2O/DEA (0.4 mL/0.1 mL) was
used. [e] Small amounts (<6% yield) of defluorinated meta-carboxylic
acid methyl esters were obtained in addition to 3d.
Entry
meta/ortho[a]
meta-Carboxylated Product 3
Yield [%][b]
32
1
87/13
13
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2[c,e]
86/14
52
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
34
3
87/13
10
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
25
4[e]
84/16
Scheme 3. Deuterium labeling experiments.
1
meta-carboxylic ester 3a-d6 as the major product (TON = 7.7)
(Scheme 3a). This result indicates that intramolecular alkyl-
to-aryl 1,4- and 1,3-rhodium shifts from the bridging ethyl
moiety to the benzene ring after hydrorhodation would be
operative in this reaction, and the 1,4-shift is the major
migration pathway. meta-Deuterated 1a-d4 afforded meta-
carboxylic ester 3a-d4 (TON = 6.4) with high D-incorporation
(0.85 D) at the ortho-position to both the phenylethyl and
ester groups, although deuteration at the phenylethyl group
was not observed significantly (Scheme 3b). Addition of
iPrOH as a proton source did not inhibit the D-incorporation
at the ortho-position (see the SI). These experiments imply
the possibility of direct intramolecular aryl-to-aryl 1,2-rho-
dium migration with 1,2-hydrogen shift. Collectively, these
labeling studies indicate that successive hydrorhodation,
alkyl-to-aryl 1,4-rhodium shift, aryl-to-aryl 1,2-rhodium shift,
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
33
5[e]
80/20
0
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
29
6[e]
88/12
0
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
7[d,e]
85/15
33
À
Scheme 4. Carboxylate-directed ortho-C H carboxylation.
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and carboxylation occurs in the generation of meta-carboxylic
acids.
SI). Medium primary KIE values ([3a]/[3a-d6] = 2.3; [3a]/
[3a-d4] = 2.7) were observed for the meta-carboxylic esters,
À
À
To gain further information on the ortho- and meta-C H
which suggests these C H bond cleavage steps would be
somewhat related to the rate-determining step of this meta-
carboxylation.
bond cleavage, kinetic isotope effects (KIEs) were evaluated
by two intermolecular competition reactions between 1a and
1a-d4, and 1a and 1a-d6 in the same reaction vessel (see the
Figure 1. Free-energy diagrams of a) hydrorhodation-1,4-migration (black) and hydrorhodation-1,3-migration (blue) and b) 1,2-rhodium migration-
meta-carboxylation (black) and ortho-carboxylation (blue) pathways computed at the M11-L/SDD(Fe, Rh)&6–311+G(d,p)(C, H, O, P), SMD-
(nBu2O)(428 K)//B3LYP/LANL2DZ(Fe, Rh)&6-31G(d,p)(C, H, O, P) level. Potential energy values relative to SM (kcalmolÀ1) are shown in the
diagrams.
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1,4-Rhodium(I) migration involving tandem oxidative
carboxylation observed in the reaction conditions. The high-
À
addition and reductive elimination of C H bonds via a five-
est activation energy for the 1,4-rhodium shift (TS 2:
25.2 kcalmolÀ1) is comparable to that for the successive 1,2-
rhodium shift (TS 8: 28.6 kcalmolÀ1), which agrees with the
results of the KIE studies (see the SI) suggesting the both
steps can be the rate-determining step of this reaction.
Moreover, the calculated relatively high energy barriers for
the tandem rhodium shift are consistent with the high
temperature required for the meta-carboxylation. We have
also computed the 1,2-rhodium shift-meta-carboxylation
pathway and the ortho-carboxylation pathway using less
bulky dcype as a ligand to get insight on the role of the dippf
ligand in this reaction (Figure S9). In contrast to dippf, the
ortho-carboxylation is calculated to be 2.7 kcalmolÀ1 more
favorable than the 1,2-rhodium shift with dcype. This is in
agreement with the experimental ortho-selectivity with dcype
(Table 1, entry 2), and suggests the importance of the bulky
dippf ligand in realizing the 1,2-rhodium migration-meta-
carboxylation over the ortho-carboxylation selectively.
membered rhodacycle intermediate has been investigated
and utilized for various catalytic reactions.[29–35] On the other
hand, direct 1,2-rhodium(I) shift on aromatic rings has not
been reported so far.[36,37] Therefore, we investigated this
uncommon 1,2-rhodium migration in more detail.
A possible pathway for the direct 1,2-rhodium shift would
be tandem carboxylation and decarboxylation sequence.
Satoh, Miura, and Larrosa reported carboxylic group-directed
formal meta-selective olefination and arylation,[38–41] where
the carboxyl group behaves as a temporary directing group in
the reaction.[42] In order to confirm whether the 1,2-rhodium
shift proceeds via ortho-carboxylic acid, ortho-carboxylate
2a’-Na was subjected to the reaction conditions (Scheme 4). It
was found that 2a’ was recovered in 83% NMR yield without
formation of the meta-carboxylic acid 2a or the decarboxy-
lated compound, suggesting the carboxylate-directed carbox-
ylation might not be operative in this reaction.
To support the above observation, time course analysis
was conducted to examine meta-/ortho-carboxylation ratios
using 1a as the substrate (Table S7). Longer reaction times
increased TONs of both meta- and ortho-carboxylic acids 2a
and 2a’, but did not change the meta/ortho ratios. These
constant meta/ortho ratios independent of the reaction time
do not agree with the possible tandem carboxylate-directed
carboxylation and decarboxylation pathway, where 2a’ would
be generated faster than 2a.
We conducted density functional theory (DFT) calcula-
tions of the postulated reaction pathway starting from RhH-
(dippf) complex SM and 1a for evaluating the validity of the
unprecedented tandem rhodium shift (Figure 1). First, the
initial hydrorhodation-1,4- or 1,3-rhodium migration pathway
is calculated (Figure 1a). Hydrorhodation of SM to 1a
proceeds with low activation barriers (TS 1: 9.3 kcal for
terminal C-Rh bond formation; TS 4: 13.5 kcalmolÀ1 for
internal C-Rh bond formation) to give s-alkyl rhodium INT 2
or p-benzyl rhodium INT 9. The following alkyl-to-aryl
rhodium migration involves two steps: oxidative addition of
A plausible mechanism based on the experimental and
computational results is summarized in Scheme 5. First,
rhodium hydride C is generated from rhodium chloride A
and NaOiPr via transmetalation and b-hydride elimination.
À
The alkene inserts into the Rh H bond of C, and the 1,4-
À
rhodium shift (major) or 1,3-rhodium shift (minor) with C H
activation afforded ortho-aryl rhodium species F. F can
undergo carboxylation to give ortho-carboxylate G. At high
temperature 1,2-rhodium shift proceeds to give meta-aryl
rhodium derivative H, which undergoes carboxylation with
CO2 to afford rhodium meta-carboxylate I. Finally, trans-
metalation with NaOiPr gives the product and regenerates
rhodium isopropoxide B. The steric repulsion between the
ligand on the rhodium and the ortho-phenethyl substituent
seems to promote this unprecedent 1,2-rhodium shift.
À
the arene C H bond to alkyl rhodium(I) to give cyclic
rhodium(III) hydride and reductive elimination of the alkyl
[43]
À
C H bond to afford ortho-aryl rhodium(I).
The highest
activation energy for the 1,4-rhodium shift (TS 2: 25.2 kcal
molÀ1 for the oxidative addition) was lower than that for the
1,3-rhodium shift (TS 6: 29.8 kcalmolÀ1 for the reductive
elimination). This result agrees with the result of deuterium
labeling experiments (Scheme 3), which shows the 1,4-rho-
dium shift is dominant. Next we compare the 1,2-rhodium
migration-meta-carboxylation pathway with the ortho-car-
boxylation pathway (Figure 1b). The 1,2-rhodium(I) shift
proceeds via h2-benzyne hydride rhodium(III) intermedi-
ate[44] INT 12 with a relatively high activation barrier of
28.6 kcalmolÀ1 (TS 8), and the following meta-carboxylation
requires less activation energy (TS 9: 26.1 kcalmolÀ1) to give
stable rhodium(I) carboxylate PD 2 (À8.9 kcalmolÀ1). In
contrast, the activation energy for the ortho-carboxylation
pathway is calculated to be 30.9 kcalmolÀ1 (TS 10), which is
2.3 kcalmolÀ1 higher than that for the 1,2-rhodium shift-meta-
carboxylation pathway, explaining the meta-selectivity of the
Scheme 5. Proposed reaction mechanism.
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[18] H. Mizuno, J. Takaya, N. Iwasawa, J. Am. Chem. Soc. 2011, 133,
1251 – 1253.
Conclusion
[19] 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 – 3779.
[20] 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 – 2090.
[21] 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 – 478.
[22] W.-Y. Gao, H. Wu, K. Leng, Y. Sun, S. Ma, Angew. Chem. Int.
Ed. 2016, 55, 5472 – 5476; Angew. Chem. 2016, 128, 5562 – 5566.
[23] T. Suga, H. Mizuno, J. Takaya, N. Iwasawa, Chem. Commun.
2014, 50, 14360 – 14363.
We have found the meta-selective carboxylation of diaryl-
ethylene derivatives with a rhodium catalyst with a bulky
dippf ligand, NaOiPr, and CO2. This carboxylation reaction is
the first example of meta-selective carboxylation. The deute-
rium labeling studies and DFT calculations suggest that the
reaction proceeds mainly via hydrorhodation, followed by
sequential alkyl-to-aryl 1,4-rhodium shift and unusual aryl-to-
aryl 1,2-rhodum shift. This carboxylation reaction would offer
new possibilities in the development of meta-selective func-
tionalization reactions.
[24] T. Suga, T. Saitou, J. Takaya, N. Iwasawa, Chem. Sci. 2017, 8,
1454 – 1462.
[25] S. Manzini, N. Huguet, O. Trapp, R. A. Paciello, T. Schaub, Catal.
Today 2017, 281, 379 – 386.
Acknowledgements
[26] D. W. Arnold, S. E. Bradforth, E. H. Kim, D. M. Neumark, J.
Chem. Phys. 1995, 102, 3493 – 3509.
[27] S. Li, W. Yuan, S. Ma, Angew. Chem. Int. Ed. 2011, 50, 2578 –
2582; Angew. Chem. 2011, 123, 2626 – 2630.
This research was supported by JSPS KAKENHI Grant
Number 15H05800 and 17H06143.
[28] Very recently, Martin reported remote sp2 C H carboxylation
À
with 1,4-nickel migration. See: M. Bçrjesson, D. Janssen-Mꢀller,
B. Sahoo, Y. Duan, X. Wang, R. Martin, J. Am. Chem. Soc. 2020,
142, 16234 – 16239.
Conflict of Interest
[29] K. Oguma, M. Miura, T. Satoh, M. Nomura, J. Am. Chem. Soc.
2000, 122, 10464 – 10465.
The authors declare no conflict of interest.
[30] T. Hayashi, K. Inoue, N. Taniguchi, M. Ogasawara, J. Am. Chem.
Soc. 2001, 123, 9918 – 9919.
[31] J. Zhang, J.-F. Liu, A. Ugrinov, A. F. X. Pillai, Z.-M. Sun, P.
Zhao, J. Am. Chem. Soc. 2013, 135, 17270 – 17273.
[32] E. A. B. Kantchev, F. Zhou, S. R. Pangestu, M. B. Sullivan, H.
Su, Eur. J. Org. Chem. 2015, 7114 – 7121.
À
Keywords: carboxylation · C H activation ·
meta-functionalization · rhodium · rhodium migration
[33] B. M. Partridge, M. Callingham, W. Lewis, H. W. Lam, Angew.
Chem. Int. Ed. 2017, 56, 7227 – 7232; Angew. Chem. 2017, 129,
7333 – 7338.
[34] M. Callingham, B. M. Partridge, W. Lewis, H. W. Lam, Angew.
Chem. Int. Ed. 2017, 56, 16352 – 16356; Angew. Chem. 2017, 129,
16570 – 16574.
[35] N. Liu, J. Yao, L. Yin, T. Lu, Z. Tian, X. Dou, ACS Catal. 2019, 9,
6857 – 6863.
[36] Formal 1,2-rhodium migration via oxidative addition and
reductive elimination on RhIII aryl hydride complex is reported.
See: A. D. Selmeczy, W. D. Jones, M. G. Partridge, R. N. Perutz,
Organometallics 1994, 13, 522 – 532.
[37] 1,2-Palladium shift via aryne-palladium complexes is postulated
in some catalytic reactions. See: a) A. C. Sather, S. L. Buchwald,
Acc. Chem. Res. 2016, 49, 2146 – 2157; b) K. Matsushita, R.
Takise, K. Muto, J. Yamaguchi, Sci. Adv. 2020, 6, eaba7614.
[38] S. Mochida, K. Hirano, T. Satoh, M. Miura, Org. Lett. 2010, 12,
5776 – 5779.
[1] J. Yang, Org. Biomol. Chem. 2015, 13, 1930 – 1941.
[2] F. F. Khan, S. K. Sinha, G. K. Lahiri, D. Maiti, Chem. Asian J.
2018, 13, 2243 – 2256.
[3] D. Leow, G. Li, T.-S. Mei, J.-Q. Yu, Nature 2012, 486, 518 – 522.
[4] Y.-F. Yang, G.-J. Cheng, P. Liu, D. Leow, T.-Y. Sun, P. Chen, X.
Zhang, J.-Q. Yu, Y.-D. Wu, K. N. Houk, J. Am. Chem. Soc. 2014,
136, 344 – 355.
[5] R.-Y. Tang, G. Li, J.-Q. Yu, Nature 2014, 507, 215 – 220.
[6] G. Yang, P. Lindovska, D. Zhu, J. Kim, P. Wang, R.-Y. Tang, M.
Movassaghi, J.-Q. Yu, J. Am. Chem. Soc. 2014, 136, 10807 –
10813.
[7] H.-J. Xu, Y. Lu, M. E. Farmer, H.-W. Wang, D. Zhao, Y.-S. Kang,
W.-Y. Sun, J.-Q. Yu, J. Am. Chem. Soc. 2017, 139, 2200 – 2203.
[8] H.-J. Xu, Y.-S. Kang, H. Shi, P. Zhang, Y.-K. Chen, B. Zhang, Z.-
Q. Liu, J. Zhao, W.-Y. Sun, J.-Q. Yu, Y. Lu, J. Am. Chem. Soc.
2019, 141, 76 – 79.
[9] X.-C. Wang, W. Gong, L.-Z. Fang, R.-Y. Zhu, S. Li, K. M. Engle,
J.-Q. Yu, Nature 2015, 519, 334 – 338.
[39] J. Cornella, M. Righi, I. Larrosa, Angew. Chem. Int. Ed. 2011, 50,
9429 – 9432; Angew. Chem. 2011, 123, 9601 – 9604.
[40] J. Luo, S. Preciado, I. Larrosa, J. Am. Chem. Soc. 2014, 136,
4109 – 4112.
[10] P.-X. Shen, X.-C. Wang, P. Wang, R.-Y. Zhu, J.-Q. Yu, J. Am.
Chem. Soc. 2015, 137, 11574 – 11577.
[11] Z. Dong, J. Wang, G. Dong, J. Am. Chem. Soc. 2015, 137, 5887 –
5890.
[41] M. Font, A. R. A. Spencer, I. Larrosa, Chem. Sci. 2018, 9, 7133 –
7137.
[12] J. Wang, G. Dong, Chem. Rev. 2019, 119, 7478 – 7528.
[13] O. Saidi, J. Marafie, A. E. W. Ledger, P. M. Liu, M. F. Mahon, G.
Kociok-Kçhn, M. K. Whittlesey, C. G. Frost, J. Am. Chem. Soc.
2011, 133, 19298 – 19301.
[14] A. J. Paterson, S. St John-Campbell, M. F. Mahon, N. J. Press,
C. G. Frost, Chem. Commun. 2015, 51, 12807 – 12810.
[15] N. Hofmann, L. Ackermann, J. Am. Chem. Soc. 2013, 135, 5877 –
5884.
[16] K. Korvorapun, R. Kuniyil, L. Ackermann, ACS Catal. 2020, 10,
435 – 440.
[17] K. Korvorapun, M. Moselage, J. Struwe, T. Rogge, A. M.
Messinis, L. Ackermann, Angew. Chem. Int. Ed. 2020, 59,
18795 – 18803; Angew. Chem. 2020, 132, 18956 – 18965.
[42] There are also some reports on rhodium(I)-catalyzed decarbox-
ylation of fluorinated benzoic acids. See: a) Z.-M. Sun, P. Zhao,
Angew. Chem. Int. Ed. 2009, 48, 6726 – 6730; Angew. Chem.
2009, 121, 6854 – 6858; b) Z.-M. Sun, J. Zhang, P. Zhao, Org. Lett.
2010, 12, 992 – 995; c) F.-Q. Shi, Org. Lett. 2011, 13, 736 – 739.
[43] Concerning the 1,3- and 1,4-rhodium migrations, there are two
possible diastereomeric pathways derived from the rhodium
stereocenter and the benzylic carbon stereocenter. Here we
show the less energy-demanding pathway for each rhodium
migration. For comparison of the diastereomeric pathways, see
the SI (Figure S8).
&&&&
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These are not the final page numbers!

Angewandte
Research Articles
Chemie
[44] There is a report of isolation of h2-benzyne rhodium complex,
Williamson, C. D. Incarvito, L. N. Zakharov, A. L. Rheingold,
Organometallics 2002, 21, 4873 – 4885.
RhCp*(PMe3) (C6F4). See: R. P. Hughes, R. B. Laritchev, A.
Manuscript received: July 15, 2021
Accepted manuscript online: August 16, 2021
Version of record online: && &&
,
&&&&
Angew. Chem. Int. Ed. 2021, 60, 2 – 10
ꢀ 2021 Wiley-VCH GmbH
www.angewandte.org
&&&&
These are not the final page numbers!

Angewandte
Research Articles
Chemie
Research Articles
À
Homogeneous Catalysis
meta-Selective C H carboxylation of 1,1-
diarylethylene derivatives has been ach-
ieved by using a bulky rhodium catalyst
under a CO2 atmosphere. Experimental
and computational mechanistic studies
indicate that tandem hydrorhodation and
rhodium migrations, which include
unique aryl-to-aryl 1,2-rhodium migra-
tion, are operative in the reaction con-
ditions.
T. Saito, J. Caner, N. Toriumi,
N. Iwasawa*
&&&& — &&&&
À
Rhodium-Catalyzed meta-Selective C H
Carboxylation Reaction of 1,1-
Diarylethylenes via Hydrorhodation-
Rhodium Migration
&&&&
www.angewandte.org
ꢀ 2021 Wiley-VCH GmbH
Angew. Chem. Int. Ed. 2021, 60, 2 – 10
These are not the final page numbers!