Nickel-Catalyzed Acyl Group Transfer of o-Alkynylphenol Esters Accompanied by C?O Bond Fission for Synthesis of Benzo[b]furan

Article abstract of DOI:10.1002/cctc.202001949

Herein, we report the nickel-catalyzed cascade C?O bond cleavage/cyclization of ortho-alkynylphenyl ester to construct a 3-acylbenzo[b]furan skeleton. As a result of reaction condition screening, the Ni(0)/IAd (1,3-Di(1-adamantyl)imidazole-2-ylidene) system was found to be optimal for catalytic conversion. Interestingly, the reaction exclusively gives 3-acylbenzo[b]furan instead of a decarbonylated product frequently observed in reactions mediated by acyl-nickel species. The catalyst loadings could be reduced to 5–10 mol %. We demonstrated the synthesis of a variety of functionalized 3-acylbenzofuran derivatives. We conducted stoichiometric study of nickel complexes as well as density functional theory (DFT) calculations to support a possible reaction mechanism.

Full text of DOI:10.1002/cctc.202001949

Full Papers
doi.org/10.1002/cctc.202001949
ChemCatChem
Nickel-Catalyzed Acyl Group Transfer of o-Alkynylphenol
Esters Accompanied by CÀ O Bond Fission for Synthesis of
Benzo[b]furan
Ryohei Doi,*[a] Koji Shimizu,[b] Yuma Ikemoto,[a] Masashi Uchiyama,[a] Mikiko Koshiba,[a]
Atsushi Furukawa,[a] Katsumi Maenaka,[a, c, d] Satoshi Watanabe,[b] and Yoshihiro Sato*[a]
Herein, we report the nickel-catalyzed cascade CÀ O bond
cleavage/cyclization of ortho-alkynylphenyl ester to construct a
3-acylbenzo[b]furan skeleton. As a result of reaction condition
screening, the Ni(0)/IAd (1,3-Di(1-adamantyl)imidazole-2-
ylidene) system was found to be optimal for catalytic
conversion. Interestingly, the reaction exclusively gives 3-
acylbenzo[b]furan instead of a decarbonylated product fre-
quently observed in reactions mediated by acyl-nickel species.
The catalyst loadings could be reduced to 5–10 mol%. We
demonstrated the synthesis of a variety of functionalized 3-
acylbenzofuran derivatives. We conducted stoichiometric study
of nickel complexes as well as density functional theory (DFT)
calculations to support a possible reaction mechanism.
Introduction
chemists by their unique and diverse reactivities.[4] In fact,
various coupling reactions of esters catalyzed by nickel
complexes have been reported to date.[5]
We aimed to develop a distinct type of a catalytic acylation
with an ester to expand the scope of catalytic ester trans-
formation. Most reactions using ester as an acylating reagent
rely on organometallic or heteroatom nucleophiles. We focused
on alkynes as coupling partner of ester under nickel catalysis.[6]
Kurahashi and Matsubara reported coupling reactions of
salicylic acid ketals with internal alkynes to obtain chromones
(Scheme 1a).[6a] Synthetic methods of cyclopentenones by
Ester has been examined as a source of an acyl metal complex,
which is a crucial intermediate for a variety of CÀ C and C-
heteroatom bond-forming processes. In contrast to corrosive
and moisture sensitive acid chlorides and anhydrides, an ester
is a fascinating acyl metal precursor due to availability and easy
handling. Meanwhile, the oxidative addition of a relatively
stable acyl CÀ O bond would be a critical step. Noble transition-
metal catalysts such as palladium, iridium, and ruthenium have
been used for coupling esters with or without a decarbon-
ylation path.[1,2] The high potential of low-valent nickel com-
plexes for activation of phenyl esters under mild conditions was
suggested by Yamamoto in 1980.[3] Ni complexes are not only
alternatives to costly metal ones but also captivating organic
[a] Dr. R. Doi, Y. Ikemoto, M. Uchiyama, M. Koshiba, Dr. A. Furukawa,
Prof. K. Maenaka, Prof. Y. Sato
Faculty of Pharmaceutical Sciences
Hokkaido University
Kita 12-jo Nishi 6-chome
Kita-ku, Sapporo 060–0812 (Japan)
E-mail: doi@pharm.hokudai.ac.jp
biyo@pharm.hokudai.ac.jp
[b] Dr. K. Shimizu, Prof. S. Watanabe
Department of Materials Engineering
The University of Tokyo
7-3-1 Hongo
Bunkyo-ku, Tokyo 113–8656 (Japan)
[c] Prof. K. Maenaka
Global Station for Biosurfaces and Drug Discovery
Hokkaido University
Kita 12-jo Nishi 6-chome
Kita-ku, Sapporo 060–0812 (Japan)
[d] Prof. K. Maenaka
Center for Life Innovation
Hokkaido University
Kita 12-jo Nishi 6-chome
Kita-ku, Sapporo 060–0812 (Japan)
Scheme 1. Nickel-catalyzed ester-alkyne couplings. When an alkyne was
unsymmetrical, regioisomers were obtained in several cases.
Supporting information for this article is available on the WWW under
https://doi.org/10.1002/cctc.202001949.
ChemCatChem 2021, 13, 2086–2092
2086
© 2021 Wiley-VCH GmbH

Full Papers
doi.org/10.1002/cctc.202001949
ChemCatChem
coupling reactions of α,β-unsaturated phenyl esters with Results and Discussion
alkynes were developed by Ohashi/Ogoshi and Montgomery
(Scheme 1b).[6b,c] These reactions are believed to proceed via
oxidative cyclization on Ni(0), supported by a stoichiometric
reaction provided in the Ohashi/Ogoshi’s report. Cramer
succeeded in developing a novel enantioselective variant.[6d]
Montgomery and Zimmerman recently applied this cycloaddi-
tion to a reductive three-component coupling of enoates,
alkynes, and aldehydes (Scheme 1c).[6f] An ester-alkyne reaction
mediated by carbometallation of alkyne with Ni and arylboronic
acid is also reported.[6e] In this context, we focused on 5-endo-
dig cyclization of 2-alkynyl phenols which has been utilized for
the synthesis of benzo[b]furans (Scheme 1d).[7] Herein, we
demonstrate Ni(0)/IAd (IAd=1,3-Di(1-adamantyl)imidazole-2-
ylidene) catalyst system to synthesize 3-acylbenzo[b]furan,
which is a privileged structure represented by marketed drugs
such as Amiodarone and Dronedarone,[8] via intramolecular CÀ C
bond formation of ester and alkyne groups accompanied by
acyl CÀ O bond cleavage.
We commenced our study by treating aryl p-toluate 1a
possessing an o-alkynyl group on phenol ring with various
nickel catalyst systems in THF (Table 1). When we tested
phosphine ligands, we were not able to obtain the desired
product 2a in a catalytic manner (entries 1, 2, and 4–6),
although, interestingly, the desired product was obtained in
good yield by using a stoichiometric amount of Ni(cod)2 and
PCy3 (entry 3). It is noteworthy that the product was a ketone
which was generated by circumventing a decarbonylation path.
One of the significant concerns to categorize catalytic CÀ C
coupling of esters via acyl CÀ O bond disconnection would be
the existence of
a decarbonylation event of an acyl-Ni
intermediate.[9] Yamaguchi and Itami discovered that, in the
presence of a nickel catalyst, decarbonylative coupling reactions
of esters occurred at high temperatures by removing carbon
monoxide from the coordination sphere of a nickel center.[9a–c,e]
In contrast, nickel-catalyzed CÀ C bond forming reactions of
esters to give ketones are limited, probably due to a competing
decarbonylation path that kicks the catalyst out of a productive
cycle via formation of an inert nickel carbonyl complex. Also,
Table 1. Reaction development for benzo[b]furan synthesis: ligand screening.[a]
Entry
Ligand
Yield of 2a[b]
SM rec.
1
PPh3
PCy3
PCy3
N. D.
1%
75%
4%
6%
N. D.
28%
47%
13%
99%
95%[g]
Quant.
81%
N. D.
84%
88%
Quant.
16%
N. D.
33%
N. D.
N. D.
2
3[c]
4
PCy2Ph
Xantphos
DCPE
IMes·HCl
IPr·HCl
ICy·HCl
IAd·HBF4
IAd·HBF4
5[d]
6[d]
7[e]
8[e]
9[e]
10[e]
11[f]
[a] N. D.=not detected. [b] 1H NMR yield determined by using 1,1,2,2-tetrachloroethane as an internal standard. [c] 1 equiv. Ni(cod)2 and 2 equiv. PCy3 were
loaded. [d] 10 mol% of ligand was used. [e] 20 mol% NaOtBu was added to generate a free carbene in situ. [f] 1.0 mmol of 1a, 5 mol% of Ni(cod)2, IAd·HBF4
°
and NaOtBu were used in DMF at 50 C. [g] Isolated yield.
ChemCatChem 2021, 13, 2086–2092
www.chemcatchem.org
2087
© 2021 Wiley-VCH GmbH

Full Papers
doi.org/10.1002/cctc.202001949
ChemCatChem
heating the reaction mixture to expedite the CÀ C coupling of
an acyl nickel intermediate would face a dilemma owing to a
simultaneous promotion of a decarbonylation process. For
cases. The compound having two phenyl rings delivered the
desired product 2b, of which the structure was determined by
X-ray crystallography. Substrates having electron-withdrawing
and -donating group on benzoyl applied to acyl transfer (2c,
2d). In addition to m-tolyl (2e), sterically demanding o-tolyl or
1-naphthyl group posed no problem to give desired benzofur-
ans 2f and 2g in high yields. Aliphatic esters such as 1h–k
having methyl, primary, and secondary alkyl groups gave the
products in excellent yields. It is noteworthy that alkene (2j) or
a cyclobutane ring (2k) was not affected by nickel catalysis.
Next, we surveyed the effect of alkyne terminus. Compounds
having 3-tolyl, 4-methoxyphenyl, and 4-tert-butylphenyl were
transformed into desired products 2l, 2m, and 2o in good to
acceptable yields. Note that alkynes carrying an electron-
instance, Love and co-workers obtained
a mixture of a
decarbonylation product (biaryl) and a benzophenone deriva-
tive by Ni-catalyzed coupling of arylboronic acids with phenyl
esters.[10] Nonetheless, a report by Cavallo, Rueping, and co-
workers demonstrated alkylation of phenyl ester by using Ni/
monodentate phosphine catalyst system to synthesize
ketones.[11]
This interesting phenomenon encouraged us to continue a
ligand screening campaign to achieve a high catalytic turnover.
Reactions using NHC (N-Heterocyclic Carbene) ligand precursors
were found to give the desired ketone 2a in a catalytic manner
(entries 7–10). Among the NHCs tested, IAd was the most
effective ligand to deliver the product (entry 10). After further
optimization study, we found that the reaction using 1.0 mmol
of 1a proceeds quantitatively with 5 mol% Ni(cod)2 and IAd in
DMF (entry 11).[12] We confirmed that IAd or NaOtBu itself did
not promote the reaction, corroborating the nickel catalysis
participation.
withdrawing group gave
a poor result (2n), though a
fluorinated arene had no deteriorating effects to obtain 2p in
91% yield. The reaction of 1q possessing an aliphatic alkyne
terminus was sluggish. We got the product 2q in only 21%
with 20 mol% catalyst loadings. The reaction of the alkyne
having a 2-naphthyl group also resulted in a relatively low yield.
We prepared compound 2s having methyl and methoxy groups
in excellent yield which we used for the mechanistic study (vide
infra). Substituted benzofurans 2t–2v were synthesized in good
yields.
We applied our optimized reaction condition to a variety of
substrates (Table 2). We noticed that the reactions gave better
°
results when reaction mixtures were heated at 100 C in many
Table 2. Substrate scope.
°
°
°
°
°
Isolated yields were given. [a] 50 C, 1 h, [b] 10 mol%, 18 h, [c] 100 C, 18 h, [d] 100 C, 2 h, [e] 16 h, [f] 10 mol%, 100 C, 18 h, [g] 20 mol%, 100 C, 18 h.
ChemCatChem 2021, 13, 2086–2092
www.chemcatchem.org
2088
© 2021 Wiley-VCH GmbH

Full Papers
doi.org/10.1002/cctc.202001949
ChemCatChem
Although Ni(cod)2 has been recognized as one of the most
competent low-valent nickel sources, the instability toward
heat, light, and air is a well-known drawback of the reagent. A
glove box equipped with a freezer, which is essential to store
pure Ni(cod)2, was required to set up our reaction. Recently,
Cornella and co-workers has developed an air-stable Ni(Fstb)3
(Fstb=(E)-1,2-bis(4-(trifluoromethyl)phenyl)ethene) as an alter-
native low-valent nickel source.[13] Thus, we examined the
catalytic activity of Ni(Fstb)3 for our reaction to demonstrate a
glove box-free manipulation (Scheme 2). Catalytic amounts of
Ni(Fstb)3, IAd·HBF4 and NaOtBu were weighed in the air and
were added to a Schlenk flask equipped with a stirring bar and
a nitrogen-filled balloon. The reaction mixture was heated at
°
100 C under nitrogen atmosphere after addition of compound
1 dissolved in dry DMF by cannulation. As a result, we obtained
the desired product 2a in 89% yield. We believe that this result
significantly lowered a barrier to conduct our reaction in many
synthetic scenes.
We switched our attention to mechanistic studies. We
conducted a cross-over experiment using substrate 1a and 1m
to check whether the reaction was intramolecular or intermo-
lecular. As a result, we only observed intramolecular coupling
product 2a and 2m (Scheme 3).
Scheme 2. A reaction using air-stable Ni(Fstb)3 without the aid of a glove
box.
Possible intramolecular reaction mechanisms are described
in Figure 1. In the path A, which is our initial working
hypothesis, the reaction would be initiated by CÀ O bond
cleavage of substrate 1 with Ni(0) complex to give acyl nickel
intermediate I. Benzofuranyl complex II is formed by 5-endo-dig
cyclization. Reductive elimination gives 3-acylbenzofuran 2 and
regenerates Ni(0) species. In this case, we should rationalize the
possible decarbonylation from intermediate II. The other
plausible path based on a proposed mechanism by Cho’s report
would begin with oxidative cyclization on Ni(0) to forge a CÀ C
bond between ester and alkyne.[14] The β-oxygen elimination of
intermediate III gives zwitterionic intermediate IV. In the path B,
which is analogous mechanism of Cho’s report, sequential
rotation around CÀ C bonds occurs to form the intermediate VII
via the intermediates V and VI. Upon reductive elimination of
VII, benzofuran 2 is generated. Oxidative cyclization involving
ester is uncommon although aldehydes, ketones and imines
undergo the process which is supported by isolation of well-
defined nickelacycle complexes.[15] Yet the multiple CÀ C bond
rotation is not supported by experimental facts, the mechanism
is consistent with the complete absence of a decarbonylated
product. We also considered the conjugate addition of zwitter-
ionic intermediate IV to form a benzofuran ring as a nickel
enolate complex (path C) which emerged in the process of the
DFT calculation shown later.
Scheme 3. A cross-over experiment. Condition: 0.1 mmol 1a, 0.1 mmol 1m,
0.02 mmol Ni(cod)2, 0.02 mmol IAd·HBF4, 0.02 mmol NaOtBu, DMF (1 mL),
1
°
100 C, 18 h. Yields were estimated by H NMR analysis of crude mixture.
We studied the acyl CÀ O bond activation step with the Ni-
NHC system. Previously a stoichiometric reaction of aryl ester
with Ni(0)-NHC system was examined by Shi.[16] They revealed
that treatment of phenyl 1-naphthoate with Ni(cod)2, ICy·HCl
and NaOtBu at room temperature gave an acylnickel complex
connected to a chlorine atom probably derived from the
imidazolium salt (Scheme 4a). Besides, they demonstrated the
reversibility of decarbonylation and carbonylation by heating in
toluene or addition of carbon monoxide gas. We were
interested in the oxidative addition reaction of Ni(0) complex
ligated by ItBu instead of IAd, a truncated ligand used in the
computational study (vide infra), with aryl ester as a model of
Figure 1. A possible catalytic cycle. L=Ligand.
ChemCatChem 2021, 13, 2086–2092
www.chemcatchem.org
2089
© 2021 Wiley-VCH GmbH

Full Papers
doi.org/10.1002/cctc.202001949
ChemCatChem
Figure 2. ORTEP diagram of 5 with 30% probability level. Hydrogen atoms
were omitted for clarity.
Scheme 4. Oxidative addition of esters.
the initial step in our postulated catalytic cycle.[17] When Ni(cod)2
and ItBu was mixed in C6D6, we observed no free 1,5-cyclo-
octadiene. The NMR spectrum ruled out pre-coordination of
ItBu ligand to Ni(0). Therefore, to check the reactivity of a Ni(0)-
ItBu complex with an aryl ester, we decided to use Ni-
(ItBu)(styrene)2 3 as a Ni(0) source.[18] When the complex 3 was
treated with phenyl benzoate in THF-d8, the reaction was
sluggish at room temperature: Conversion of ester was less
than 50% even after 1 day at ambient temperature. Note that
Shi’s reaction ended up with a chlorine complex instead of a
phenoxide. In our catalytic reaction, ester 1 is carrying an alkyne
moiety, which would be playing a pivotal role to accelerate the
reaction via coordination. Thus, we next tested the reactivity of
3 with 8-quinolinyl benzoate 4 of which a nitrogen atom would
coordinate to the nickel center. We are aware of Sun’s report
using compound 4 to observe acyl CÀ O bond activation with
Fe(PMe3)4 which generated a phenyl Fe(II) complex via decar-
bonylation (Scheme 4b).[19] Upon mixing in THF, the reaction of
3 with 4 occurred to form an orange precipitate which was
identified as square-planar acyl nickel complex 5 by X-ray
crystallography (Scheme 4c and Figure 2). Quantitative forma-
tion of aryloxy nickel 5 implies the significance of a coordinat-
ing group on an aryloxy ring to drive the forward reaction.
Furthermore, taking Sun’s observation of decarbonylation into
account, the formation of an acyl complex would be a unique
property of a NiÀ ItBu complex. To characterize the solution-
Figure 3. Microcrystal electron microscopic analysis of complex 6 at 0.85 Å
resolution at 90 K. (a) Low magnification TEM image (x6700) of micro-crystal.
Scale bar is corresponding to 1 μm. (b) Electrostatic potential map of
complex 6. 2FoÀ Fc map contoured at 3.0 σ. Green, red, blue and magenta are
atoms of carbon, oxygen, nitrogen and nickel, respectively.
The initial structure A was suggested by CREST at the GFN2-xTB
level as the lowest conformer.[22] We first examined the path A
described in Figure 1. The calculated activation barrier for the
oxidative addition step to give complex B was 28.4 kcal/mol.
We propose rearrangement of the 2-(phenylethynyl)phenol unit
to reach intermediate E via isomerization to complex C, which
is reminiscent of flexible coordination behavior of the 8-
quinolinol ligand attached to complexes 5 and 6, followed by a
phenoxide ring rotation (the intermediate was optimized as
complex D).[23] The transition-state TS2 for the cyclization step
required the lower energy than TS1 did. Reductive elimination
of complex E via TS3 would produce the target compound as
an η2-complex F. We examined possible decarbonylation paths
(Figure S1). If the reaction proceeded via the path A, the
decarbonylation of intermediate E was possible but reductive
elimination to release decarbonylated product was hampered
by a relatively high activation barrier (for detail, see Supporting
Information).
1
phase structure of complex 5, we conducted H and 13C NMR
experiments using CD2Cl2 as a solvent. Interestingly, the signals
of 5 gradually diminished and a set of new signals appeared
which was assigned to isomer 6 with the aid of MicroED
analysis of crystals grown from CHCl3/pentane (Figure 3. See
also Supporting Information for detail of characterization).
We performed DFT calculations for the model reaction
between 2b and Ni(0)/ItBu to shed light on the energy diagram
(Figure 4) using the Gaussian 16 package.[20] A calculation
method utilized in the Houk’s related work covering Ni, NHC
and alkyne was applied with modification of solvent to DMF.[21]
We next studied the path B and C. Oxidative cyclization was
calculated to be slightly favored to give a nickelacycle G. The
energy barrier was estimated to be only 16.7 kcal/mol. We
ChemCatChem 2021, 13, 2086–2092
www.chemcatchem.org
2090
© 2021 Wiley-VCH GmbH

Full Papers
doi.org/10.1002/cctc.202001949
ChemCatChem
Figure 4. Reaction profile with proposed structures of intermediates and transition-states based on DFT calculations. a) Free energy diagram (kcal/mol). b)
Reaction paths with structures of intermediates. L=ItBu. c) Structures of transition-states.
optimized the structures of intermediates H and I but failed to Conclusion
find some transition-states that connect these intermediates.
Reductive elimination of intermediate I through TS5 was
disfavored to reach complex F. At this moment, the path B is
also a possible reaction course, but we need further exploration
to conclude the path is working. In contrast, we succeeded to
find a reasonable transition-state TS6 for intramolecular con-
jugate addition of intermediate H. Therefore, our calculation
indicate that the path C is the most plausible mechanism for
our reaction.
In summary, we have developed a Ni-catalyzed acyl group
transfer reaction to build up a benzo[b]furan ring. NHC ligand
was found to be necessary for catalytic turnover. Reactions
using Ni(cod)2 and IAd was applicable for a variety of substrates.
Besides, we demonstrated that air-stable Ni(Fstb)3 worked as an
efficient Ni(0) source enabling a glove box-free reaction set-up.
The reaction mechanism was examined through a cross-over
experiment, a stoichiometric reaction using Ni(ItBu)(styrene)2
complex, and DFT calculations which rationalized why our
reaction give ketones instead of biaryls. The development of
ChemCatChem 2021, 13, 2086–2092
www.chemcatchem.org
2091
© 2021 Wiley-VCH GmbH

Full Papers
doi.org/10.1002/cctc.202001949
ChemCatChem
Szostak, Organometallics 2017, 36, 3784–3789; j) P. Lei, G. Meng, S. Shi,
Y. Ling, J. An, R. Szostak, M. Szostak, Chem. Sci. 2017, 8, 6525–6530;
k) A. H. Dardir, P. R. Melvin, R. M. Davis, N. Hazari, M. M. Beromi, J. Org.
Chem. 2018, 83, 469–477; l) G. Li, S. Shi, P. Lei, M. Szostak, Adv. Synth.
Catal. 2018, 360, 1538–1543; m) J. Masson-Makdissi, J. K. Vandavasi, S. G.
Newman, Org. Lett. 2018, 20, 4094 (this paper includes decarbonylative
couplings); n) N. A. Serratore, C. B. Anderson, G. B. Frost, T.-G. Hoang,
S. J. Underwood, P. M. Gemmel, M. A. Hardy, C. J. Douglas, J. Am. Chem.
Soc. 2018, 140, 10025–10033; o) M. B. Kurosawa, R. Isshiki, K. Muto, J.
Yamaguchi, J. Am. Chem. Soc. 2020, 142, 7386–7386.
reactions targeting other heterocycles by acyl transfer reaction
under nickel catalysis is currently underway in our laboratory.
Acknowledgements
We appreciate Dr. Keitaro Yamashita (MRC-LMB) and Dr. Haruaki
Yanagisawa (The University of Tokyo) for the kind advice with the
data collection and analysis of MicroED. Dr. Shunsuke Kita
(Hokkaido University) and Dr. Masato Sumi (Hokkaido University)
are acknowledged for kind help to set up the environment of
MicroED data analysis. This work was supported in part by
Grants-in-Aid for Scientific Research (B) (No. 20H03360) from the
Japan Society for the Promotion of Science (JSPS) and by Grants-
in-Aid for Regional R&D Proposal-Based Program from Northern
Advancement Center for Science & Technology of Hokkaido Japan.
The Akiyama Life Science Foundation is also acknowledged for the
financial support. This work was partly achieved through the use
of the supercomputer system at the information initiative center,
Hokkaido University, Sapporo, Japan. We gratefully acknowledge
the Center for Computational Materials Science, Institute for
Materials Research, Tohoku University for the use of MASAMUNE-
IMR (MAterials science Supercomputing system for Advanced
MUlti-scale simulations towards NExt-generation - Institute for
Materials Research). This work was also supported by the Platform
Project for Supporting in Drug Discovery and Life Science Research
(Basis for Supporting Innovative Drug Discovery and Life Science
Research (BINDS)) under Grant Number 20am0101093 and the
Middle Molecule Project under Grant Number 20ae0101047h from
Japan Agency for Medical Research and Development (AMED), the
Hokkaido University Biosurface Project and Global Station for
Biosurfaces and Drug Discovery, a project of Global Institution for
Collaborative Research and Education (GI-CoRE) at Hokkaido
University.
[3] a) J. Ishizu, T. Yamamoto, A. Yamamoto, Chem. Lett. 1976, 1091–1094;
b) T. Yamamoto, J. Ishizu, T. Kohara, S. Komiya, A. Yamamoto, J. Am.
Chem. Soc. 1980, 102, 3758–3764.
[4] S. Z. Tasker, E. A. Standley, T. F. Jamison, Nature 2014, 509, 299–309.
[5] a) R. Takise, K. Muto, J. Yamaguchi, Chem. Soc. Rev. 2017, 46, 5864–5888;
b) L. Guo, M. Rueping, Acc. Chem. Res. 2018, 51, 1185–1195; c) T. B. Boit,
A. S. Bulger, J. E. Dander, N. K. Garg, ACS Catal. 2020, 10, 12109–12126.
[6] a) A. Ooguri, K. Nakai, T. Kurahashi, S. Matsubara, J. Am. Chem. Soc.
2009, 131, 13194–13195; b) M. Ohashi, T. Taniguchi, S. Ogoshi, J. Am.
Chem. Soc. 2011, 133, 14900–14903; c) A. D. Jenkins, A. Herath, M. Song,
J. Montgomery, J. Am. Chem. Soc. 2011, 133, 14460–14466; d) J. S. E.
Ahlin, P. A. Donets, N. Cramer, Angew. Chem. Int. Ed. 2014, 53, 13229–
13233; Angew. Chem. 2014, 126, 13445–13449; e) S. N. Karad, H. Panchal,
C. Clarke, W. Lewis, H. W. Lam, Angew. Chem. Int. Ed. 2018, 57, 9122–
9125; Angew. Chem. 2018, 130, 9260–9263; f) A. D. Jenkins, M. T. Robo,
P. M. Zimmerman, J. Montgomery, J. Org. Chem. 2020, 85, 2956–2956.
[7] Arisawa and co-workers have recently reported nickel-catalyzed benzo
[b]furan synthesis via CÀ O bond cleavage of vinyl ether using 2,2’:6’,2’’-
terpyridine as an ancillary ligand: S. Ohno, J. Qiu, R. Miyazaki, H.
Aoyama, K. Murai, J.-y. Hasegawa, M. Arisawa, Org. Lett. 2019, 21, 8400–
8403.
[8] Benzofuran natural product as synthetic target: a) H. Khanam, Shamsuz-
zaman, Eur. J. Med. Chem. 2015, 97, 483–504; b) M. M. Heravi, V.
Zadsirjan, H. Hamidi, P. H. T. Amiri, RSC Adv. 2017, 7, 24470–24521.
[9] Ni-catalyzed decarbonylative CÀ C couplings of esters: a) K. Muto, J.
Yamaguchi, K. Itami, J. Am. Chem. Soc. 2012, 134, 169–172; b) K. Amaike,
K. Muto, J. Yamaguchi, K. Itami, J. Am. Chem. Soc. 2012, 134, 13573–
13573; c) K. Muto, J. Yamaguchi, D. G. Musaev, K. Itami, Nat. Commun.
2015, 6, 7508; d) X. Liu, J. Jia, M. Rueping, ACS Catal. 2017, 7, 4491–
4496; e) T. Okita, K. Muto, J. Yamaguchi, Org. Lett. 2018, 20, 3132–3135.
[10] N. A. LaBerge, J. A. Love, Eur. J. Org. Chem. 2015, 5546–5553.
[11] A. Chatupheeraphat, H.-H. Liao, W. Srimontree, L. Guo, Y. Minenkov, A.
Poater, L. Cavallo, M. Rueping, J. Am. Chem. Soc. 2018, 140, 3724–3735.
[12] For detail of further optimization, see Table S1 in Supporting Informa-
tion.
[13] L. Nattmann, R. Saeb, N. Nöthling, J. Cornella, Nat. Can. 2020, 3, 6–13.
[14] S. D. Tambe, N. Iqbal, E. J. Cho, Org. Lett. 2020, 22, 8550–5884.
[15] a) J. Montgomery, Angew. Chem. Int. Ed. 2004, 43, 3890–3908; Angew.
Chem. 2004, 116, 3980–3998; b) Y. Hoshimoto, M. Ohashi, S. Ogoshi,
Acc. Chem. Res. 2015, 48, 1746–1755; c) S. Ogoshi, Bull. Chem. Soc. Jpn.
2017, 90, 1401–1406.
Conflict of Interest
The authors declare no conflict of interest.
[16] X. Pu, J. Hu, Y. Zhao, Z. Shi, ACS Catal. 2016, 6, 6692–6698.
[17] We confirmed that ItBu also works as
a suitable ligand for full
conversion of 1b into 2b.
Keywords: Nickel · Carbene ligands · Oxygen heterocycles ·
Density functional calculations · Electron diffraction
[18] J. Strautmann, R. Paciello, T. Schaub, F. Eickemeyer, D. Loeffler, H.
Wilmer, U. Radius, J. Berthel, F. Hering, US20170175267 A1, 2017.
[19] Y. Lu, X. Li, L. Wang, H. Sun, Inorg. Chem. Commun. 2014, 41, 51.
[20] Full reference and detailed calculation method is written in the
Supporting Information.
[1] A recent review for decarbonylative couplings with transition-metal
catalysts: H. Lu, T.-Y. Yu, P.-F. Xu, H. Wei, Chem. Rev. 2021, 121, 365–411.
[2] Noble metal catalysts without decarbonylation: a) R. Kakino, I. Shimizu,
A. Yamamoto, Bull. Chem. Soc. Jpn. 2001, 74, 371–376; b) H. Tatamidani,
K. Yokota, F. Kakiuchi, N. Chatani, J. Org. Chem. 2004, 69, 5615–5621;
c) H. Tatamidani, F. Kakiuchi, N. Chatani, Org. Lett. 2004, 6, 3597–3599;
d) M. Murai, K. Miki, K. Ohe, Chem. Commun. 2009, 3466–3468 (In this
report, Ni was also effective to deliver the product though Pd was the
catalyst of choice); e) G. T. Hoang, V. J. Reddy, H. H. K. Nguyen, C. J.
Douglas, Angew. Chem. Int. Ed. 2011, 50, 1882–1884; Angew. Chem.
2011, 123, 1922–1924; f) J. Wang, S. Zuo, W. Chen, X. Zhang, K. Tan, Y.
Tian, J. Wang, J. Org. Chem. 2013, 78, 8217–8231; g) G. T. Hoang, Z. Pan,
J. T. Brethorst, C. J. Douglas, J. Org. Chem. 2014, 79, 11383–11394;
h) T. B. Halima, W. Zhang, I. Yalaoui, X. Hong, Y.-F. Yang, K. N. Houk, S. G.
Newman, J. Am. Chem. Soc. 2017, 139, 1311–1318; i) S. Shi, P. Lei, M.
[21] X. Hong, P. Liu, K. N. Houk, J. Am. Chem. Soc. 2013, 135, 1456–1462.
[22] a) C. Bannwarth, S. Ehlert, S. Grimme, J. Chem. Theory Comput. 2019, 15,
1652–1671; b) P. Pracht, F. Bohle, S. Grimme, Phys. Chem. Chem. Phys.
2020, 22, 7169.
[23] a) J.-B. Liu, X. Zhang, Y.-Y. Tian, X. Wang, X.-K. Zhu, D.-Z. Chen, Dalton
Trans. 2019, 48, 15059–15067; b) Y. Yang, Y. Liu, R. Zhu, D. Zhang, Inorg.
Chem. 2020, 59, 4741–4752.
Manuscript received: December 7, 2020
Revised manuscript received: January 20, 2021
Accepted manuscript online: February 1, 2021
Version of record online: February 23, 2021
ChemCatChem 2021, 13, 2086–2092
www.chemcatchem.org
2092
© 2021 Wiley-VCH GmbH