Synthesis of Indenones via Palladium-Catalyzed Ligand-Free Carbonylation

Article abstract of DOI:10.1002/adsc.201901309

A palladium-catalyzed ligand-free carbonylation reaction has been developed for the synthesis of indenones. Under CO atmosphere, this cascade reaction proceeded smoothly to provide the desired indenones in moderate to excellent yields with good functional-group compatibility. The mechanistic investigations suggested the in situ formation of palladium nanoparticles and this transformation was driven by a controlled reaction sequence of alkyne insertion followed by carbonylation and annulation to form the indenone framework. (Figure presented.).

Full text of DOI:10.1002/adsc.201901309

Title: Synthesis of Indenones via Palladium-Catalyzed Ligand-Free
Carbonylation
Authors: Juan Song, Haisen Sun, Wei Sun, Yuxuan Fan, Cui Li,
Haotian Wang, Kang Xiao, and Yan Qian
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10.1002/adsc.201901309
Advanced Synthesis & Catalysis
COMMUNICATION
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Synthesis of Indenones via Palladium-Catalyzed Ligand-Free
Carbonylation
Juan Song*, Haisen Sun, Wei Sun, Yuxuan Fan, Cui Li, Haotian Wang, Kang Xiao and
Yan Qian
Key Laboratory for Organic Electronics and Information Display and Institute of Advanced Materials, Nanjing Univer-sity
of Posts and Telecommunications, Nanjing 210023, Jiangsu, China
E-mail: iamjsong@njupt.edu.cn
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######.((Please
delete if not appropriate))
Ru3(CO)12-catalyzed carbonylation reaction of aromatic
Abstract. A palladium-catalyzed ligand-free carbonylation
reaction has been developed for the synthesis of indenones.
Under CO atmosphere, this cascade reaction proceeded
smoothly to provide the desired indenones in moderate to
excellent yields with good functional-group compatibility.
The mechanistic investigations suggested the in situ
formation of palladium nanoparticles and this transfor-
mation was driven by a controlled reaction sequence of
alkyne insertion followed by carbonylation and annulation
to form the indenone framework.
imines and olefins (5 atm. of CO, Scheme 1, b, eq.1).
Chatani’s group[12c] reported
a Rh-catalyzed three-
component carbonylative cyclization of alkynes with 2-
bromophenylboronic acid leading to indenones by CO
insertion in 2007. And later, Morimoto's group[12b] reported
a similar reaction by decarbonylation of formaldehyde and
sequential carbonylation in 2009 (Scheme 1, b, eq. 2).
Although palladium-catalyzed carbonylation reactions
have been well studied and employed to manufacture a
range of important industrial products, the -acidic CO
binding to palladium resulting in the difficulty of oxidative
addition to aryl halides and also remarkably decrease the
catalytic efficiency because of the formation of palladium
black. To overcome the inherent limitation of these
carbonylation reactions, most of the processes have
utilized the ligands to keep the catalytic activity and
lifetime of catalysts.[17] Thus, development of a ligand-free
Keywords: palladium-catalyzed; ligand-free;
carbonylation; indenones.
Indenones, widely existing in natural products and
synthetically bioactive molecules,[1] have attracted
considerable synthetic interests and a number of methods
have been developed including intramolecular cyclization,
[2]
two-component annulation[3-11] and a few examples of
palladium-catalyzed
carbonylation
reaction
under
three-component annulation.[12] However, most of starting
substrates of intramolecular cyclization were not readily
commercially available and therefore suffered from
multiple-step syntheses or narrow substrate scopes. Up to
now, researches of efficient methods for preparation of
indenones mainly have focused on two-component
atmospheric pressure remains a challenge. Herein, we
disclosed the first report on the construction of in denones
by
a
ligand-free Pd-catalyzed
multi-component
cyclocarbonylation of o-bromoaryl iodides with alkynes
annulation,
including
transition-metal-mediated
[5-9]
cyclization,[3],
radical cyclization,[11] Friedel-Crafts-
type cyclization[4] and so on. Among them, the preferred
strategies are Rh[9] or Pd[7] catalyzed annulation of alkynes
with ortho-functionalized arenes(Scheme 1, a), which are
usually time-requiring multiple functional transformation
and thus less efficiency in a synthetic sequence. Therefore,
it would be appealing if the introduction of carbonyl
functional group of indenones through CO insertion rather
than tedious pre-carbo-functionalized arenes. In the past
decades, transition-metal-catalyzed carbonylation reactions
have become a powerful tool for the direct construction of
a wide variety of carbonyl-containing compounds. CO is
employed as a
less expensive, atom-economical and
readily available C1 feedstock in a broad range of
industrial chemical processes. In 1997, Murai’s group[12d]
reported a method for the preparation of indenones by
Scheme 1. Construction of Indenones
1
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10.1002/adsc.201901309
Advanced Synthesis & Catalysis
under ambient pressure of CO (Scheme 1, c). In this
cascade transformation, three new carbon–carbon single
bonds were formed in one operation and thus a simple and
efficient protocol for the construction of the indenone
framework was established by readily available substrates.
In an initial attempt, commercially available o-
bromophenyl iodide (1a) and diphenylacetylene (2a) were
chosen for the exploration of this palladium-catalyzed
PdCl2 exhibited a marginal higher yield (85%, Table 1,
entry 14). Surprisingly, the yield of 3aa was further
improved to 95% when reducing the solvent from 2 mL to
1 mL (Table 1, entry 14 versus entry 16), and almost all
diphenylacetylene (2a) was quantitatively converted into
indenone 3aa as decreasing the base of Na2CO3 loading
from 3 equiv. to 2 equiv. (Table 1, entry 16 versus entry
17). Thus, a highly efficient Pd-catalyzed three-component
carbonylation reaction was successfully established and the
optimal reaction conditions were summarized as following:
the reaction was carried out with o-bromophenyl iodide
(1a, 2 equiv.), diphenylacetylene (2a, 1 equiv.), PdCl2 (10
mol%), Na2CO3 (2 equiv.) and TBAB (1 equiv.) under a
balloon CO atmosphere in 1,4-dioxane (1 mL) at 100 °C
for 24 h. With this optimal procedure, up to 97% of
indenone 3aa was isolated.
cyclocarbonylation reaction under
a
balloon CO
atmosphere. In the presence of Pd(CH3CN)2Cl2/dppp (1,3-
bis(diphenylphosphaneyl)propane) as the catalyst, KOAc
as the base and PivOH as an additive in 1,4-dioxane at 100
oC for 24 h, to our delightfulness, it was found that 13% of
the desired indenone (3aa) was observed. This preliminary
result inspired us to further optimize this novel
carbonylation reaction. Subsequently, the effects on the
reaction with various factors, such as palladium catalyst
precursors, ligands, bases and so on, were carefully
examined. Unfortunately, no improved result was
obtained.[13] Among the experimental results, it was noted
that 12% of 3aa was achieved in a reaction in the absence
of ligand (Table 1, entry 1), together with the observation
of quite a lot of palladium black. This result strongly
suggested that ligands might be unnecessary in the reaction.
Therefore, our efforts were devoted to seeking an
appropriate condition, which can prevent the formation of
palladium black, in other words, some additives were
needed to stabilize the potential Pd(0). Accordingly, the
yield of 3aa was significantly improved to 80% when 1
equiv. of tetra-n-butyl ammonium bromide (TBAB) was
introduced to the reaction system (Table 1, entry 3). Again,
the bases and the solvents were screened another time but
no improvement anymore (Table 1, entries 4-11). In the
investigation of palladium sources (Table 1, entries 12-15),
The optimized reaction conditions were then applied to
extend the generality of this newly established cascade Pd-
catalyzed three-component transformation. A variety of
alkynes were subjected to the reactions with o-
bromophenyl iodide (1a) under CO atmosphere. The
results were summarized in Table 2. The diarylacetylenes
bearing either electron-donating groups, such as, Me (3ab),
OMe (3ac, 3ah), t-Bu (3ad) or electron-withdrawing
groups, such as, CF3 (3ae), F (3af), Cl (3ag) at para- or
meta- position were well tolerated and proceeded smoothly
to afford the corresponding products in good to excellent
yields (78%-98%) (Scheme 2) and no obvious electron
effect of the substituents were observed from these
experimental results. However, the diarylacetylenes with
groups at ortho-position, such as, OCH3 (3ak), CF3 (3al),
afforded the corresponding indenones in low yields, which
indicating a significant steric effect, and owing to the small
steric profile of Cl and F, the ortho-chloro- and fluoro-
substituted diphenylacetylene could be unexpectedly well
tolerated and the corresponding indenone product 3ai and
3aj were obtained in good yield (95% or 72%). It was
noteworthy that 1,2-di(2-thiophenyl)ethyne was an effecti-
ve substrate for the transformation and produced the
corresponding product 3am in 77% yield. This result was
extremely attractive because the thiophene contained
motifs are widely used as the functionalized organic
materials with their characteristic properties, while the
syntheses of this type compounds have remained challenge
in many transition-metal-catalyzed reactions where the
catalysts can be usually deactivated by sulfur. Furthermore,
a dialkylacetylene, 4-octyne, was also applied to the
procedure, providing the annulation product 3an in good
yield (84%). However, in the case of diethyl but-2-
ynedioate, no product obtained in the reaction. Some
unsymmetrical internal alkynes were also tested in the
reaction, except phenylethyne that no desired product
obtained, all unsymmetrical alkynes gave the mixture of
regio-isomers (3ao, 3ap, 3aq, 3ar). For trimethylsilyl
phenylacetylene, a mixture 3ao was isolated in 71% yield,
and the ratio of two regio-isomers was 6.5:1, indicating the
impact of steric hindrance on regioselectivities. The
unsymmetrical alkyne bearing methyl and phenyl groups
also gave a mixture of regio-isomers (3ap), the ratio of
which was 5:1. Interestingly, if o-bromophenyl iodide (1a)
was replaced by o-chlorophenyl iodide, the corresponding
product of 3aa was obtained in 70% yield. However, no
Table 1. Screen of Reaction Conditions a
a
Reaction conditions: 1a (0.5 mmol), 2a (0.25 mmol), Pd
(10 mol%), base (0.75 mmol), additive (0.25 mmol) under
o
CO (balloon) in solvent (2 mL) at 100 C for 24 h. The
yields were determined by GC with naphthalene as the
b
o
c
internal standard. 80 C. 1 mL of solvent. d 2 equiv. of
Na2CO3. e isolated yield.
2
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10.1002/adsc.201901309
Advanced Synthesis & Catalysis
3aa obtained for 1,2-dibromobenzene, and only 10% yield
of 3aa obtained for 1,2-diiodobenzene.
desired product together with the observation of Pd-black.
Interestingly, introducing TBAB crucially changed the
reaction. This result was reminiscent of literature reports
that quaternary ammonium salts facilitated the formation
Table 2. Scope of alkyne substrates a
Table 3. Scope of o-bromophenyl iodide derivatives a
a Reaction Conditions: 1 (0.5 mmol), 2a (0.25 mmol),
PdCl2 (0.025 mmol), Na2CO3 (0.5 mmol), TBAB (0.25
mmol), 1, 4-dioxane (1 mL) at 100 oC for 24 h under CO
(balloon). Isolated yield.
and stabilization of Pd nanoparticles.[14] [16] We speculated
,
that the PdII precursor was in situ reduced into Pd0 as
nanoparticles. To verify the assumption, both mercury and
ligand poisoning studies[15-16] were conducted. Either
a
Reaction conditions: 1a (0.5 mmol), 2 (0.25 mmol),
PdCl2 (0.025 mmol), Na2CO3 (0.5 mmol), TBAB (0.25
o
mmol), 1, 4-dioxane (1 mL) at 100 C for 24h under CO
(1atm balloon). Isolated yield. b o-bromophenyl iodide (1a)
c
was replaced by 1,2-dibromobenzene. o-bromophenyl
d
iodide (1a) was replaced by o-chlorophenyl iodide. o-
bromophenyl iodide (1a) was replaced by 1,2-
diiodobenzene.
Successively, the scope of various substituted o-
bromophenyl iodides with diphenylacetylene (2a) were
examined under the optimized conditions. As shown in
Table 3, the catalytic system could tolerate a variety of
functional substituents on o-bromophenyl iodide and gave
the corresponding indenones in moderate to excellent
yields (60%-99%). Except for the extremely electron-
withdrawing NO2 group (3fa), the electron nature of the
substituents on the phenyl ring had no evidently effect on
the reaction (3ba, 3ca, 3da, 3ea, 3ga, 3ha, 3ia, 3ja), and
the lower yields of 3ka and 3la could be attributed to their
steric hindrance.
During our initial reaction conditions screening, it was
found that the presence of the ligands did not favor to
fulfill the three-component transformation. While without
the ligands, the reaction could provide a comparable
Scheme 2. Mechanistic Investigations
3
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10.1002/adsc.201901309
Advanced Synthesis & Catalysis
To an oven dried Schlenk tube containing PdCl2 (4.4 mg,
10 mol %), TBAB (80.6 mg, 0.25 mmol), Na2CO3 (53.0
mg, 0.5 mmol) and diphenylacetylene (44.6 mg, 0.25
mmol). A balloon filled with CO was connected to the
Schlenk tube via the side tube and purged 3 times. Then o-
bromoiodobenzene (141.0 mg, 0.5 mmol) was added to the
tube. 1, 4-dioxane was then added to the tube via a syringe.
addition of 10 equiv. of Hg or 40 mol% of PPh3 to the
reaction mixture,[13] no product was found under the
standard condition, which suggested that TBAB stabilized
palladium nanoparticles might the true catalyst.
Furthermore, it was no doubted that oxidative addition of
C-I bond to palladium nanoparticles to form arylpalladium
intermediate was the first step in the catalytic cycle.
However, which step occurred first between carbonylation
or alkynes insertion (Scheme 2, path A and path B)?
According the product structure presented in Table 3, path
B sounded more reasonable. For example, using 1h as the
substrate, path A and path B would give different product
3ca and 3ha respectively, and only 3ha obtained in the
reaction. Both 3ca and 3ha were known compounds and
easily identified with 13C NMR spectrum (Scheme 2).
o
The Schlenk tube was heated at 100 C for 24h and then
cooled to room temperature. After the balloon gas was
released carefully, the reaction was quenched by water and
extracted with ethyl acetate three times. The combined
organic layers were dried over anhydrous Na2SO4 and
evaporated under vacuum. The desired products were
obtained in the corresponding yields after purification by
flash chromatography on silica gel with hexane/ethyl
acetate.
With the above evidence,
a
proposed reaction
mechanism was then figured out in Scheme 3. In the prese-
nce of CO and TBAB, PdII precursor was reduced to Pd0
nanoparticles firstly, followed by the oxidative addition of
C-I bond to form the intermediate A. Subsequently, alkyne
insertion generated the intermediate B, and on the surface
of nano-Pd0 cluster, C-Br converted to C-Pd bond by
oxidative addition to form the intermediate C. Finally, the
catalytic cycle completed by a sequence of CO insertion
and reductive elimination to afford the desired indenone
and regenerate the active catalyst.
Acknowledgements
This work was supported by the National Natural Science Foun-
dation of China (21573111), Key Laboratory of Organic Synthe-
sis of Jiangsu Province (KJS1747), the Funding from Nanjing
University of Posts and Telecommunications (NY219058,
NY217072, NY215016, NY215079).
References
[1] a) R. Nigam, K. R. Babu, T. Ghosh, B. Kumari, D.
Akula, S. N. Rath, P. Das, R. Anindya, F. A. Khan,
Bioorg. Med. Chem. 2018, 26, 4100-4112; b) T. A.
Unzner, A. S. Grossmann, T. Magauer, Angew. Chem.
Int. Ed. 2016, 55, 9763-9767; c) P.-C. Lv, M. S. A.
Elsayed, K. Agama, C. Marchand, Y. Pommier, M.
Cushman, J. Med. Chem. 2016, 59, 4890-4899; d) J. T.
Mohr, M. R. Krout, B. M. Stoltz, Nature 2008, 455,
323-332; e) A. Morrell, M. Placzek, S. Parmley, B.
Grella, S. Antony, Y. Pommier, M. Cushman, J. Med.
Chem. 2007, 50, 4388-4404; f) D. G. Nagle, Y. D.
Zhou, P. U. Park, V. J. Paul, I. Rajbhandari, C. J. G.
Duncan, D. S. Pasco, J. Nat. Prod. 2000, 63, 1431-
1433.
Scheme 3. Proposed reaction mechanism
[2] a) B. Zhou, H. Yang, H. Jin, Y. Liu, J. Org. Chem.
2019; b) J. Guo, X. Peng, X. Wang, F. Xie, X. Zhang,
G. Liang, Z. Sun, Y. Liu, M. Cheng, Y. Liu, Org.
Biomol. Chem. 2018, 16, 9147-9151; c) J. Fang, M.
Brewer, Org. Lett. 2018, 20, 7384-7387; d) S. Zhang,
X.-T. Bai, D.-Y. Chen, P. Chen, Q.-Q. Zhang, Y.-B.
Wang, RSC Adv. 2017, 7, 31142-31147; e) M. E.
Domaradzki, Y. Long, Z. She, X. Liu, G. Zhang, Y.
Chen, J. Org. Chem. 2015, 80, 11360-11368; f) C. Y.
Wang, J. Y. Yang, X. C. Cheng, E. D. Li, Y. Z. Li,
Tetrahedron Lett. 2012, 53, 4402-4404.
[3] a) W. Yu, W. Zhang, Z. Liu, Y. Zhang, Chem.
Commun. 2016, 52, 6837-6840; b) M. Ueda, T. Ueno,
Y. Suyama, I. Ryu, Chem. Commun. 2016, 52, 13237-
13240; c) L. H. Kong, X. F. Yang, X. K. Zhou, S. J.
Yu, X. W. Li, Org. Chem. Front. 2016, 3, 813-816;
[4] a) A. G. K. Reddy, G. Satyanarayana, J. Org. Chem.
2016, 81, 12212-12222; b) P. Zhao, Y. Liu, C. Xi, Org.
Lett. 2015, 17, 4388-4391; c) X. Yan, S. Zou, P. Zhao,
C. Xi, Chem. Commun. 2014, 50, 2775-2777;
In summary, we have successfully developed an
appealing approach for the construction of indenones via a
ligand-free
palladium-catalyzed
three-component
carbonylation reaction by using commercially available o-
bromophenyl iodide derivatives and internal alkynes as
substrates under a balloon CO atmosphere. This newly
developed methodology is able to accommodate a variety
of substrates and affords the anticipated products in
moderate to excellent yields. This reaction may become a
useful alternative approach for the synthesis of acridones
derivatives. The desired indenones can be obtained in short
reaction steps when such substrates are readily available.
This cascade strategy provides the potential application in
the field of medicinal chemistry and material science.
Experimental Section
General Procedure for the Synthesis of Indenones
[5] a) L. Ilies, Y. Arslanoglu, T. Matsubara, E. Nakamura,
Asian J. Org. Chem. 2018, 7, 1327-1329; b) X. Yu, S.
4
This article is protected by copyright. All rights reserved.

10.1002/adsc.201901309
Advanced Synthesis & Catalysis
Geng, G. Liu, W. Guo, J. Wang, J. Organomet. Chem.
2019, 879, 139-143;
Wender, T. J. Paxton, T. J. Williams, J. Am. Chem.
Soc. 2006, 128, 14814-14815;
[6] a) F. Liu, Z. Dong, J. Wang, G. Dong, Angew. Chem.
Int. Ed. 2019; b) B. Suchand, G. Satyanarayana, J. Org.
Chem. 2017, 82, 372-381; c) T. Furusawa, T.
Morimoto, N. Oka, H. Tanimoto, Y. Nishiyama, K.
Kakiuchi, Chem. Lett. 2016, 45, 406-408; d) A. N.
Butkevich, B. Ranieri, L. Meerpoel, I. Stansfield, P.
Angibaud, A. Corbu, J. Cossy, Org. Biomol. Chem.
2014, 12, 728-731;
[7] a) K. Ramesh, G. Satyanarayana, Eur. J. Org. Chem.
2018, 2018, 4135-4146; b) W. Guo, S. Wu, T. Wang,
Q. Xie, Y. Duan, S. Luo, J. Wang, X. Yu, Org. Chem.
Front. 2018, 5, 1613-1621; c) J. Feng, G. P. Lu, M. F.
Lv, C. Cai, J. Org. Chem. 2014, 79, 10561-10567; d) J.
Zhang, F. Yang, Y. Wu, Appl. Organomet. Chem.
2011, 25, 675-679; e) H. Tsukamoto, Y. Kondo, Org.
Lett. 2007, 9, 4227-4230; f) J. Vicente, J. A. Abad, B.
Lopez-Pelaez, E. Martinez-Viviente, Organometallics
2002, 21, 58-67; g) A. A. Pletnev, Q. Tian, R. C.
Larock, J. Org. Chem. 2002, 67, 9276-9287; h) R. C.
Larock, Q. Tian, A. A. Pletnev, J. Am. Chem. Soc.
1999, 121, 3238-3239; i) R. C. Larock, M. J. Doty, S.
Cacchi, J. Org. Chem. 1993, 58, 4579-4583; j) W. Tao,
L. J. Silverberg, A. L. Rheingold, R. F. Heck,
Organometallics 1989, 8, 2550-2559;
[11] a) K. Sun, X.-L. Chen, S.-J. Li, D.-H. Wei, X.-C. Liu,
Y.-L. Zhang, Y. Liu, L.-L. Fan, L.-B. Qu, B. Yu, K. Li,
Y.-Q. Sun, Y.-F. Zhao, J. Org. Chem. 2018, 83, 14419-
14430; b) B. Banerji, L. Majumder, S. Adhikary,
Chemistryselect 2018, 3, 1381-1384; c) Z. Yan, J. Xie,
C. Zhu, Adv. Synth. Catal. 2017, 359, 4153-4157; d) J.
Wen, W. Shi, F. Zhang, D. Liu, S. Tang, H. Wang, X.-
M. Lin, A. Lei, Org. Lett. 2017, 19, 3131-3134; e) S. B.
Nagode, A. K. Chaturvedi, N. Rastogi, Asian J. Org.
Chem. 2017, 6, 453-457; f) C. Pan, B. Huang, W. Hu,
X. Feng, J.-T. Yu, J. Org. Chem. 2016, 81, 2087-2093.
[12] a) Y. Kuninobu, T. Matsuki, K. Takai, Org. Lett.
2010, 12, 2948-2950; b) T. Morimoto, K. Yamasaki, A.
Hirano, K. Tsutsumi, N. Kagawa, K. Kakiuchi, Y.
Harada, Y. Fukumoto, N. Chatani, T. Nishioka, Org.
Lett. 2009, 11, 1777-1780; c) Y. Harada, J. Nakanishi,
H. Fujihara, M. Tobisu, Y. Fukumoto, N. Chatani, J.
Am. Chem. Soc. 2007, 129, 5766-5771; d) T.
Fukuyama, N. Chatani, F. Kakiuchi, S. Murai, J. Org.
Chem. 1997, 62, 5647-5650.
[13] The details were summarized in support information.
[14] H. Bonnemann, W. Brijoux, R. Brinkmann, E.
Dinjus, T. Joussen, B. Korall, Angew. Chem. Int. Ed.
1991, 30, 1312-1314;
[8] a) N. Lv, Z. Chen, Y. Liu, Z. Liu, Y. Zhang, Org. Lett.
2017, 19, 2588-2591; b) M. J. Rosenfeld, B. K. R.
Shankar, H. Shechter, J. Org. Chem. 1988, 53, 2699-
2705;
[15] a) Q. Zhou, S. Wei, W. Han, J. Org. Chem. 2014, 79,
1454-1460. b) Y. Zhu, L. Chuanzhao, A. O. Biying, M.
Sudarmadji, A. Chen, T. Dang Thanh, A. M. Seayad,
Dalton Trans. 2011, 40, 9320-9325;
[9] a) X. Yu, Y. Duan, W. Guo, T. Wang, Q. Xie, S. Wu,
C. Jiang, Z. Fan, J. Wang, G. Liu, Organometallics
2017, 36, 1027-1034; b) Y. Yokoyama, Y. Unoh, R. A.
Bohmann, T. Satoh, K. Hirano, C. Bolm, M. Miura,
Chem. Lett. 2015, 44, 1104-1106; c) Z. Qi, M. Wang,
X. Li, Org. Lett. 2013, 15, 5440-5443; d) Y. Chen, F.
Wang, W. Zhen, X. Li, Adv. Synth. Catal. 2013, 355,
353-359; e) S. Chen, J. Yu, Y. Jiang, F. Chen, J.
Cheng, Org. Lett. 2013, 15, 4754-4757; f) B.-J. Li, H.-
Y. Wang, Q.-L. Zhu, Z.-J. Shi, Angew. Chem. 2012,
124, 4014-4018; g) T. Miura, M. Murakami, Org. Lett.
2005, 7, 3339-3341; k) K. Kokubo, K. Matsumasa, M.
Miura, M. Nomura, J. Org. Chem. 1996, 61, 6941-
6946;
[16] J. A. Widegren, R. G. Finke, J. Mol. Catal. A-Chem.
2003, 198, 317-341.
[17] a) X. F. Wu, H. Neumann, M. Beller, Chem. Rev.
2013, 113, 1-35; b) X. F. Wu, H. Neumann, M. Beller,
Chem. Soc. Rev. 2011, 40, 4986-5009; c) R. Grigg, S. P.
Mutton, Tetrahedron 2010, 66, 5515-5548; d) A.
Brennfuhrer, H. Neumann, M. Beller, Angew. Chem.
Int. Ed. 2009, 48, 4114-4133; e) C. F. J. Barnard, Org.
Process Res. Dev. 2008, 12, 566-574; f) C. F. J.
Barnard, Organometallics 2008, 27, 5402-5422.
[10] a) P. Chuangsoongnern, C. Surinrach, J. Tummatorn,
C. Thongsornkleeb, S. Ruchirawat, Eur. J. Org. Chem.
2017, 5102-5109; b) T. Kawase, J.-i. Nishida, Chem.
Rec. 2015, 15, 1045-1059; c) K. R. Babu, F. A. Khan,
Org. Biomol. Chem. 2015, 13, 299-308; d) P. A.
5
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Advanced Synthesis & Catalysis
COMMUNICATION
Synthesis of Indenones via Palladium-Catalyzed
Ligand-Free Carbonylation
Adv. Synth. Catal. Year, Volume, Page – Page
Juan Song*, Haisen Sun, Wei Sun, Yuxuan Fan,
Cui Li, Haotian Wang, Kang Xiao and Yan Qian
6
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