Rapid Formation of Fluoren-9-ones via Palladium-Catalyzed External Carbon Monoxide-Free Carbonylation

Article abstract of DOI:10.1002/adsc.201800155

A Pd-catalyzed carbonylation reaction for the synthesis of fluoren-9-ones from 2-halogenated biphenyls using phenyl formate as a carbon monoxide surrogate was achieved. The combined use of cesium carbonate and o-anisic acid resulted in a remarkable rate e

Full text of DOI:10.1002/adsc.201800155

Title: Rapid Formation of Fluoren-9-ones via Palladium-Catalyzed
External Carbon Monoxide-Free Carbonylation
Authors: Hideyuki Konishi, Suguru Futamata, Xi Wang, and Kei
Manabe
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.201800155
Link to VoR: http://dx.doi.org/10.1002/adsc.201800155

10.1002/adsc.201800155
Advanced Synthesis & Catalysis
COMMUNICATION
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Rapid Formation of Fluoren-9-ones via Palladium-Catalyzed
External Carbon Monoxide-Free Carbonylation
Hideyuki Konishi,a Suguru Futamata,a Xi Wang,a and Kei Manabea,*
a
School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
E-mail: manabe@u-shizuoka-ken.ac.jp
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######.
ease and can form CO under weakly basic conditions.
synthesis of fluoren-9-ones from 2-halogenated biphenyls We envisaged that if the CO used in the catalytic
Abstract. A Pd-catalyzed carbonylation reaction for the
using phenyl formate as a carbon monoxide surrogate was
achieved. The combined use of cesium carbonate and o-
anisic acid resulted in a remarkable rate enhancement,
where the reaction was complete within 3 min in some
cases. Mechanistic studies indicated that the turnover-
limiting step of the reaction was the C–H bond-cleaving
step or the oxidative addition step, depending on the
substrate used.
synthesis of fluoren-9-ones from 2-halobiphenyls was
replaced with a CO surrogate, this synthetic method
would offer simple and practical access to fluoren-9-
ones. Actually, a similar concept was reported by
Morimoto, Kakiuchi, and co-workers, who utilized
formaldehyde[11] and furfural[12] as CO surrogates.
Although the use of CO gas was replaced with that of
surrogates in these methods, they remain to be
improved in terms of by-product formation, reaction
time, and amount of catalyst required. Herein, we
Keywords: carbon monoxide surrogate; carbonylation;
cyclization; fluoren-9-one; Pd catalysis
describe
carbonylation for the synthesis of fluoren-9-ones
using CO surrogate, phenyl formate. The
a
Pd-catalyzed
external
CO-free
a
appropriate choice of carboxylate base facilitated the
extremely rapid reaction. Furthermore, mechanistic
studies of the reaction are discussed.
Fluoren-9-ones are an important class of compounds
used in material sciences and biological research.[1]
Due to the broad utility of fluoren-9-ones, a variety of
synthetic methods have been developed, including the
classical oxidation of fluorenes and Friedel Crafts-
type acylation of 2-phenylbenzoic acid derivatives.[2]
Recently, cyclization of acyl radicals,[3] metal-
catalyzed C(sp2)–C(sp2) bond-forming reactions of 2-
arylbenzoic acids,[4] and double C–H coupling via 2-
arylbenzaldimines[5] have appeared as elegant
methods, despite several issues such as harsh reaction
conditions or relatively low product yields. On the
other hand, the metal-catalyzed carbonylation of 2-
halogenated biphenyls under carbon monoxide (CO)
is generally a high-yielding method to produce
structurally diverse fluoren-9-ones.[6] While a number
of easily accessible substrates can be applied in the
carbonylation, the reaction relies on the use of CO as
a carbonyl source. Generally, the use of CO, which is
a highly toxic gas, should be avoided due to safety
concerns.
The use of CO surrogates, which can generate CO
by chemical reactions or physical stimuli, instead of
gaseous CO, is attractive for the realization of
practical synthetic methods.[7] Our laboratory has
been interested in the potential utility of CO
surrogates, and has contributed to the development of
novel CO surrogates such as phenyl formate,[8] 2,4,6-
trichlorophenyl formate,[9] and N-formylsaccharin.[10]
These formic acid derivatives can be handled with
The Pd-catalyzed carbonylation to give fluoren-9-
one 3a was optimized using 2-iodobiphenyl (1) as a
model substrate and phenyl formate (2) as a CO
surrogate. Initial experiments showed that the base
was important for selectively obtaining 3a, with
sodium acetate and in situ-formed cesium
adamantane-1-carboxylate resulting in a high yield of
the product (entries 3 and 4). Carboxylate screening
revealed that the in situ-formed aromatic carboxylates
were effective for affording 3a in a high yield (entries
5–10). Surprisingly, the reaction proceeded very
rapidly, completing within 3 min, even when reduced
amounts of cesium carbonate and o-anisic acid were
used (entry 14).[13] This carboxylate base was better
than CsOPiv (entry 15), which was used for the
reaction under CO gas.[6] The carboxylate of o-anisic
acid gave better yield of 3a within a short reaction
time than other aromatic carboxylates. These results
might be ascribed to the subtle balance between steric
and electronic effects (entries 11–14). Therefore, o-
anisic acid was used to examine the substrate scope.
On the other hand, the use of N-formylsaccharin[10] as
a CO surrogate instead of 2 hardly promoted the
reaction (entry 16).
1
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800155
Advanced Synthesis & Catalysis
rapid formation of fluoren-9-ones from several 2-
iodobiphenyls, which required only 3 min for
reaction time under 5 mol% of Pd catalyst, was
achieved (Table 2, yields of the products are shown
in brackets). Moreover, the catalyst loading could be
lowered to 0.5 mol%, albeit resulting in a lower yield
of 3a (62%). Gram-scale (12.0 mmol scale) synthesis
of 3a was also feasible, showing the scalability of the
present synthetic method.
Table 1. Optimization of reaction conditions.
Table 2. Substrate scope of 2-iodobiphenyls[a]
Entry Base (equiv)
Time
Yield
(%)[a]
1
2
3
4
NBu3 (3.0)
14 h
14 h
14 h
14 h
11
0[b]
78
89
Na2CO3 (3.0)
NaOAc (3.0)
Cs2CO3 (1.5) + 1-AdCO2H
(3.0)
5
6
Cs2CO3 (1.5) + PhCO2H (3.0) 14 h
82
84
Cs2CO3 (1.5)
14 h
+ 4-FC6H4CO2H (3.0)
Cs2CO3 (1.5)
+ 4-(MeO)C6H4CO2H (3.0)
Cs2CO3 (1.5)
+ 4-(Me2N)C6H4CO2H (3.0)
Cs2CO3 (1.5)
+ 2-(MeO)C6H4CO2H (3.0)
Cs2CO3 (1.5)
+ 2,4-(MeO)2C6H3CO2H (3.0)
Cs2CO3 (0.75)
+ 4-(MeO)C6H4CO2H (1.5)
Cs2CO3 (0.75)
+ 4-(Me2N)C6H4CO2H (1.5)
Cs2CO3 (0.75)
+ 2-MeC6H4CO2H (1.5)
Cs2CO3 (0.75)
7
14 h
94
95
94
92
70
53
89
92
8
14 h
9
14 h
10
14 h
11[c]
12[c]
13[c]
14[c]
15[c]
3 min
3 min
3 min
3 min
+ 2-(MeO)C6H4CO2H (1.5)
CsOPiv (1.5)
3 min
1 h
58
3
16[c,d] Cs2CO3 (0.75)
+ 2-(MeO)C6H4CO2H (1.5)
[a]
[b]
Isolated yield.
obtained in 99% yield.
Phenoxycarbonylated by-product was
[c]
Pd(OAc)2 (5 mol%) and PCy3
[d]
(15 mol%) were used instead of PdCl2(PCy3)2.
N-
Formylsaccharin was used instead of 2.
[a]
Isolated yield of each product is shown followed by
Various 2-iodobiphenyls were tested to illustrate
the substrate scope in the presence of 1–5 mol% Pd
catalyst (Table 2). In most cases, a reaction time of 1
h was sufficient for the conversion of the 2-
catalyst loading (x) in parenthesis. Isolated yield of the
product obtained from the reaction using 5 mol% Pd
[b]
catalyst for 3 min is shown in square bracket.
The
reaction was performed in 12.0 mmol scale, with 1.86 g of
3a being obtained.
iodobiphenyls.
Although
2′-substituted
2-
iodobiphenyls resulted in low yields of 3m and 3n
probably due to the steric bulk of the 2-iodobiphenyls,
4- or 4′-substituted iodobiphenyls afforded the
desired fluoren-9-ones 3b–l in moderate to high
yields in the presence of 1 or 2 mol% Pd catalyst.
Sterically hindered 2,6-diphenyliodobenzene and a
pyrrole-containing substrate smoothly reacted to
afford 3o and 3p, respectively, although in both cases,
5 mol% of the catalyst was required. 3′-Substituted
and naphthyl-type substrates afforded two
regioisomeric products, with the yields reflecting the
steric effects of the substrates. Notably, extremely
Furthermore, the same reaction was applicable to
2-bromobiphenyls (Table 3). While the reaction
required 5 mol% Pd catalyst and a prolonged reaction
time (14 h), fluoren-9-ones 3a, 3c, 3i, and 3u–w were
successfully obtained from 4′-substituted 2-
bromobiphenyls and 2-thien-3-ylbromobenzene.
Notably, a bromoalkene was found to be a good
substrate for the synthesis of indenone 3x. In these
reactions, a considerable amount (~10% yield) of the
2
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800155
Advanced Synthesis & Catalysis
phenoxycarbonylated by-product was observed,
which caused a slight decrease in the product yield.
5.7 for both 6 and 7, Scheme 2A). This large KIE
value was consistent with a concerted metalation–
deprotonation (CMD) mechanism,[16,17] which has
been proposed in many Pd-catalyzed, carboxylate-
assisted C–H functionalization reactions.[18] On the
other hand, intermolecular competitive experiments
using iodobiphenyls (1 and 1-d5) or bromobiphenyls
(10 and 10-d5) exhibited almost no KIE (1.2 and 1.1,
Scheme 2B). The same situation was also observed
when two parallel reactions using bromobiphenyls
(10 and 10-d5) were performed (1.1, Scheme 2C).
However, two parallel reactions using iodobiphenyls
(1 and 1-d5) afforded relatively large KIE (3.6,
Scheme 2C). These results clearly indicated that the
turnover-limiting step (TLS) of the reaction depended
on the substrate used; the TLS of the reaction of 2-
iodobiphenyl was the C–H bond-cleaving step, while
that of 2-bromobiphenyl was not the C–H bond-
cleaving step.
Table 3. Substrate scope of 2-bromobiphenyls and a
bromoalkene[a]
[a] Isolated yield of each product is shown.
To demonstrate the utility of the reaction, we
applied it to the synthesis of a potentially diagnostic
compound for Alzheimer’s disease, which selectively
binds to β-amyloid plaques in the brain.[14] The
Suzuki-Miyaura
iodobenzene
coupling
and
of
2,4-dibromo-1-
4-(N,N-
dimethylamino)phenylboronic
acid
afforded
bromobiphenyl 4, which was converted into 5 via the
cyclocarbonylation using 2. Although the yield was
low due to the presence of two bromo groups in 4, the
target compound was concisely accessed via a two-
step procedure from commercially available materials.
Scheme 1. Two-step synthesis of bioactive compound 5.
Scheme 2. KIE experiments. Conditions: Pd(OAc)2 (5
mol%), PCy3 (15 mol%), Cs2CO3 (0.75 equiv), o-anisic
acid (1.5 equiv), 2 (2 equiv) in DMSO at 110 °C, unless
otherwise noted below. In the reactions of 1 and 1-d5,
Pd(OAc)2 (0.5 mol%) and PCy3 (1.5 mol%) were used. For
the intermolecular competition (B), 2 (4 equiv) was used.
To obtain insight into the reaction mechanism,
kinetic isotope effects (KIEs) were measured using
the appropriately deuterated 2-iodo- and 2-
bromobiphenyls.[15] A large KIE value was obtained
from the reaction of partially deuterated iodobiphenyl
6 and bromobiphenyl 7, which possessed both C–H
and C–D bonds at the relevant reactive sites (kH/kD =
3
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800155
Advanced Synthesis & Catalysis
The proposed reaction mechanism is shown in
oxidative addition step for bromides. Studies on the
expanded substrate scope, effect of o-anisic acid, and
origin of acceleration of the reaction are currently
underway.
Scheme 3. Pd(II) intermediate A, which is formed via
the oxidative addition of the substrate to Pd(0),
exchanges an anionic ligand from a halide to a
carboxylate to generate intermediate B. It reacts
intramolecularly to dissociate the C–H bond at the 2′-
position, and to generate palladacycle C via CMD.
Then, CO generated from the reaction of phenyl
formate (2) and a carboxylate undergoes coordination
and migratory insertion. Finally, the reductive
elimination of acylpalladium(II) intermediate D
affords the desired fluoren-9-one 3a and regenerates
Pd(0). Another pathway from B to D in which CO
insertion occurs to form intermediate E prior to CMD
is also feasible. The KIE studies indicated that the
TLS was the C–H bond-cleaving step for the iodides
but not for the bromides. Considering the reactivity
difference between the iodides and bromides, the
oxidative addition step was assumed to be the TLS
for bromides.
Experimental Section
All Pd catalysts, PCy3, Cs2CO3, 1, 10, 2-(2-bromoethene-
1,1,2-triyl)tribenzene (substrate used for synthesis of
compound 3x), all carboxylic acids and bases were
purchased from TCI, Wako, Kanto, and Aldrich, and used
as received. Tributylamine was purchased from Wako, and
was purified by distillation prior to use. All solvents except
DMSO were purified by distillation prior to use.
Anhydrous DMSO (“Super Dehydrated” grade) was
purchased from Wako and used as received. 2-Iodo-4'-
vinyl-1,1'-biphenyl (substrate used for the synthesis of 3f)
and 2-iodo-2'-(trifluoromethyl)-1,1'-biphenyl (substrate
used for the synthesis of 3n), and 7 were synthesized by
halogenation of corresponding 2-aminobiphenyls (for
details, see Supporting Information). Other substrates[6b,19]
[19a]
including 2,[8a] 6,[15a] 1-d5,[20] and 10-d5
synthesized according to known methods.
were
Representative experimental procedure of the synthesis
of fluoren-9-one (3a) (Table 2)
Pd(OAc)2 (2.23 mg, 10.0 µmol, 5 mol%), PCy3 (8.40 mg,
30.0 µmol, 15 mol%), 1 (56.0 mg, 0.200 mmol), o-anisic
acid (45.6 mg, 0.300 mmol, 1.50 equiv), Cs2CO3 (48.8 mg,
0.150 mmol, 0.750 equiv) and DMSO (4.0 mL) were
added in a 30-mL two-necked flask containing a magnetic
stirring bar equipped with an Ar balloon. The flask was
evacuated and backfilled with Ar three times. The flask
was warmed to 110 °C in an oil bath and stirred for 10 min.
Then, 2 (43.6 µL, 0.400 mmol, 2.00 equiv) was added to
the flask by using a syringe through a septum cap. The
reaction mixture was stirred at 110 °C for 3 min. The
reaction mixture was immediately cooled to rt and was
diluted with EtOAc and 2 M aq. NaOH, washed with H2O
and brine, dried over Na2SO4, filtered, and concentrated.
The obtained residue was purified by preparative TLC
twice (1st: CH2Cl2/hexane 1/1, 2nd: hexane/EtOAc 5/1) to
afford 3a (33.1 mg, 0.184 mmol, 92%) as a yellow solid.
Gram-scale synthesis of compound 3a (Table 2)
Pd(OAc)2 (26.9 mg, 0.120 mmol, 1 mol%), PCy3 (101 mg,
0.360 mmol, 3 mol%), 1 (3.36 g, 2.08 mL, 12.0 mmol), o-
anisic acid (2.74 g, 18.0 mmol, 1.50 equiv), Cs2CO3 (2.93
g, 9.00 mmol, 0.750 equiv) and DMSO (240 mL) were
added in a 1000-mL three-necked flask with an Ar balloon,
a magnetic stirring bar, and a thermocouple temperature
probe. The flask was evacuated and backfilled with Ar
three times. The flask was warmed to 110 °C (internal
temperature) in an oil bath and stirred for 30 min. Then, 2
(2.61 mL, 24.0 mmol, 2.00 equiv) was added to the flask
by using a syringe through a septum cap. The flask was
warmed to 110 °C in an oil bath and stirred for 1 h. The
reaction mixture was cooled to rt and was diluted with
EtOAc, washed with H2O three times, dried over Na2SO4,
filtered, and concentrated. The obtained residue was
purified by column chromatography (1st: CH2Cl2/hexane
1/1, 2nd: hexane/EtOAc 5/1) to afford 3a (1.86 g, 10.3
mmol, 86%) as a yellow solid.
Scheme 3. Proposed reaction mechanism (Ar = 2-
MeOC6H4).
In conclusion, a Pd-catalyzed simple, practical, and
external CO-free carbonylation reaction for the
synthesis of fluoren-9-ones was achieved using
phenyl formate as a CO surrogate. The reaction time
was effectively shortened by the combined use of Acknowledgements
cesium carbonate and o-anisic acid. Mechanistic
This work was partly supported by JSPS KAKENHI Grant
studies using isotopically labelled compounds
suggested that concerted metalation–deprotonation
was involved and that the turnover-limiting step was
the C–H bond-cleaving step for iodides and the
Numbers 15H04634 and 15K18834, the Uehara Memorial
Foundation, the Takeda Science Foundation, the Tokyo
Biochemical Research Foundation, and the Platform Project for
Supporting Drug Discovery and Life Science Research (Basis for
Supporting Innovative Drug Discovery and Life Science Research
4
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800155
Advanced Synthesis & Catalysis
(BINDS)) from Japan Agency for Medical Research and
Development (AMED).
[11] T. Furusawa, T. Morimoto, N. Oka, H. Tanimoto, Y.
Nishiyama, K. Kakiuchi, Chem. Lett. 2016, 45, 406–
408.
[12] T. Furusawa, T. Morimoto, Y. Nishiyama, H.
Tanimoto, K. Kakiuchi, Chem. Asian. J. 2016, 11,
2312–2315.
References
[1] a) V. Percec, M. Glodde, T. K. Bera, Y. Miura, I.
Shiyanovskaya, K. D. Singer, V. S. K. Balagurusamy,
P. A. Heiney, I. Schnell, A. Rapp, H.-W. Spiess, S. D.
Hudson, H. Duan, Nature, 2002, 419, 384–387; b) G. L.
Eakins, J. S. Alford, B. J. Tiegs, B. E. Breyfogle, C. J.
Stearman, J. Phys. Org. Chem. 2011, 24, 1119–1128;
c) P. J. Perry, M. A. Read, R. T. Davies, S. M. Gowan,
A. P. Reszka, A. A. Wood, L. R. Kelland, S. Neidle, J.
Med. Chem. 1999, 42, 2679–2684; d) M. T. Tierney, M.
W. Grinstaff, J. Org. Chem. 2000, 65, 5355–5359.
[13] CO generation from 2 was completed within 3 min in
the presence of o-anisic acid (0.75 equiv) and Cs2CO3
(0.375 equiv) in DMSO at 110 ºC, which was
confirmed by the loss of signals of 2 in 1H-NMR
analysis.
[14] C.-W. Lee, M.-P. Kung, C. Hou, H. F. Kung, Nucl.
Med. Biol. 2003, 30, 573–580.
[15] a) M. Tobisu, S. Imoto, S. Ito, N. Chatani, J. Org.
Chem. 2010, 75, 4835–4840; b) M. Gómez-Gallego, M.
A. Sierra, Chem. Rev. 2011, 111, 4857–4963; c) E. M.
Simmons, J. F. Hartwig, Angew. Chem. 2012, 124,
3120–3126; Angew. Chem. Int. Ed. 2012, 51, 3066–
3072.
[2]G. Rieveschl, F. E. Ray, Chem. Rev. 1938, 23, 287–389.
[3] a) J. Tang, S. Zhao, Y. Wei, Z. Quan, C. Huo, Org.
Biomol. Chem. 2017, 15, 1589–1592; b) R. Ruzi, M.
Zhang, K. Ablajan, C. Zhu, J. Org. Chem. 2017, 82,
12834–12839.
[16] D. Lapointe, K. Fagnou, Chem. Lett. 2010, 39, 1118–
[4]a) T. Fukuyama, S. Maetani, K. Miyagawa, I. Ryu, Org.
Lett. 2014, 16, 3216–3219; b) Z. Cai, X. Hou, L. Hou,
Z. Hu, B. Zhang, Z. Jin, Synlett, 2016, 27, 395–398.
1126.
[17] While a large KIE value was obtained, an SEAr
mechanism cannot be completely denied. See also: X.
Zhao, C. S. Yeung, V. M. Dong, J. Am. Chem. Soc.
2010, 132, 5837–5844.
[5] a) D. R. Kumar, G. Satyanarayana, Org. Lett. 2015, 17,
5894–5897; b) X.-Y. Chen, S. Ozturk, E. J. Sorensen,
Org. Lett. 2017, 19, 1140–1143.
[18] a) L. Ackermann, Chem. Rev. 2011, 111, 1315–1345;
b) D. L. Davies, S. A. Macgregor, C. L. McMullin,
Chem. Rev. 2017, 117, 8649–8709.
[6] a) M. A. Campo, R. C. Larock, Org. Lett. 2000, 2,
3675–3677; b) M. A. Campo, R. C. Larock, J. Org.
Chem. 2002, 67, 5616–5620. c) J. Song, F. Wei, W.
Sun, K. Li, Y Tian, C. Liu, Y. Li, L. Xie, Org. Lett.
2015, 17, 2106–2109.
[19] a) S. Xu, R. Chen, Z. Fu, Q. Zhou, Y. Zhang, J. Wang,
ACS Catal. 2017, 7, 1993–1997; b) M. Iwasaki, S. Iino,
Y. Nishihara, Org. Lett. 2013, 15, 5326–5329; c) B.
Wu, N. Yoshikai, Angew. Chem. 2015, 127, 8860–
8863; Angew. Chem. Int. Ed. 2015, 54, 8736–8739; d)
H. Jiang, Y. Zhang, D. Chen, B. Zhou, Y. Zhang, Org.
Lett. 2016, 18, 2032–2035; e) D. Uraguchi, N.
Kinoshita, T. Kizu, T. Ooi, J. Am. Chem. Soc. 2015,
137, 13768–13771; f) S. Pan, H. Jiang, Y. Zhang, D.
Chen, Y. Zhang, Org. Lett. 2016, 18, 5192–5195; g) S.
Ozasa, Y. Fujioka, J. Kikutake, E. Ibuki, Chem. Pharm.
Bull. 1983, 31, 1572–1581; h) M. Nayak, I. Kim, Org.
Biomol. Chem. 2015, 13, 9697–9708; i) R. Pratap, D.
Parrish, P. Gunda, D. Venkataraman, M. K. Lakshman,
J. Am. Chem. Soc. 2009, 131, 12240–12249; j) D.
Simoni, G. Giannini, M. Roberti, R. Rondanin, R.
Baruchello, M. Rossi, G. Grisolia, F. P. Invidiata, S.
Aiello, S. Marino, S. Cavallini, A. Siniscalchi, N.
Gebbia, L. Crosta, S. Grimaudo, V. Abbadessa, A. Di
Cristina, M. Tolomeo, J. Med. Chem. 2005, 48, 4293–
4299.
[7] a) T. Morimoto, K. Kakiuchi, Angew. Chem. 2004, 116,
5698–5706; Angew. Chem. Int. Ed. 2004, 43, 5580–
5588; b) L. R. Odell, F. Russo, M. Larhed, Synlett,
2012, 23, 685–698; c) L. Wu., Q. Liu, R. Jackstell, M.
Beller, Angew. Chem. 2014, 126, 6426–6436; Angew.
Chem. Int. Ed. 2014, 53, 6310–6320; d) H. Konishi, K.
Manabe, Synlett, 2014, 25, 1971–1986; e) P. Gautam, B.
M. Bhanage, Catal. Sci. Technol. 2015, 10, 4663–4702;
f) S. D. Friis, A. T. Lindhardt, T. Skrydstrup, Acc.
Chem. Res. 2016, 49, 594–605.
[8]a) T. Ueda, H. Konishi, K. Manabe, Org. Lett. 2012, 14,
3100–3103. Tsuji et al. also reported phenyl formate as
a CO surrogate: b) T. Fujihara, T. Hosoki, Y. Katafuchi,
T. Iwai, J. Terao, Y. Tsuji, Chem. Commun. 2012, 48,
8012–8014.
[9] T. Ueda, H. Konishi, K. Manabe, Org. Lett. 2012, 14,
5370–5373.
[10] T. Ueda, H. Konishi, K. Manabe, Angew. Chem. 2013,
125, 8773–8777; Angew. Chem. Int. Ed. 2013, 52,
8611–8615.
[20] G. Shi, D. Chen, H. Jiang, Y. Zhang, Y. Zhang, Org.
Lett. 2016, 18, 2958–2961.
5
This article is protected by copyright. All rights reserved.

10.1002/adsc.201800155
Advanced Synthesis & Catalysis
COMMUNICATION
Rapid Formation of Fluoren-9-ones via Palladium-
Catalyzed External Carbon Monoxide-Free
Carbonylation
Adv. Synth. Catal. Year, Volume, Page – Page
Hideyuki Konishi, Suguru Futamata, Xi Wang, and
Kei Manabe*
6
This article is protected by copyright. All rights reserved.