Iridium-catalyzed synthesis of diaryl ethers by means of chemoselective C-F bond activation and the formation of B-F bonds

Article abstract of DOI:10.1002/asia.201403130

Transition-metal-catalyzed C-F activation, in comparison with C-H activation, is more difficult to achieve and therefore less fully understood, mainly because carbon-fluorine bonds are the strongest known single bonds to carbon and have been very difficult to cleave. Transition-metal complexes are often more effective at cleaving stronger bonds, such as C(sp²)-X versus C(sp²)-X. Here, the iridium-catalyzed C-F activation of fluorarenes was achieved through the use of bis(pinacolato)diboron with the formation of the B-F bond and self-coupling. This strategy provides a convenient method with which to convert fluoride aromatic compounds into symmetrical diaryl ether compounds. Moreover, the chemoselective products of the C-F bond cleavage were obtained at high yields with the C-Br and C-Cl bonds remaining.

Full text of DOI:10.1002/asia.201403130

DOI: 10.1002/asia.201403130
Full Paper
CÀF Activation
Iridium-Catalyzed Synthesis of Diaryl Ethers by Means of
Chemoselective CÀF Bond Activation and the Formation of BÀF
Bonds
Jianping Chen, Keyan Zhao, Bingyang Ge, Chongying Xu, Dawei Wang,* and
Yuqiang Ding*[a]
Abstract: Transition-metal-catalyzed CÀF activation, in com-
parison with CÀH activation, is more difficult to achieve and
therefore less fully understood, mainly because carbon–fluo-
rine bonds are the strongest known single bonds to carbon
and have been very difficult to cleave. Transition-metal com-
plexes are often more effective at cleaving stronger bonds,
such as C(sp2)ÀX versus C(sp3)ÀX. Here, the iridium-catalyzed
CÀF activation of fluorarenes was achieved through the use
of bis(pinacolato)diboron with the formation of the BÀF
bond and self-coupling. This strategy provides a convenient
method with which to convert fluoride aromatic compounds
into symmetrical diaryl ether compounds. Moreover, the che-
moselective products of the CÀF bond cleavage were ob-
tained at high yields with the CÀBr and CÀCl bonds remain-
ing.
Introduction
Symmetrical diaryl ether polymers are very important and in-
creasingly interesting on account of their application in the
aerospace and microelectronics industries, principally in the
form of films or moldings. This is attributable to their excellent
thermal stability, electric properties, and chemical resistance.[9]
Many synthetic methods thus far reported have shown that
symmetrical diaryl ethers are important building blocks for
large varieties of natural and artificial products (Scheme 1).
The past decade has seen the extremely rapid growth of CÀH
activation, which is considered to be an innovative, environ-
mentally benign synthetic tool. The reason for this acceptance
is that such procedures provide economical routes, achievable
in steps, to the desired or natural compounds from simple
starting materials.[1] Compared with CÀH activation, transition-
metal-catalyzed CÀF activation[2] is more difficult to achieve
and less fully understood,[3] mainly because carbon–fluorine
bonds are the strongest known single bonds to carbon and
have been very difficult to cleave.[4] Scientists have devoted
great efforts to this matter.[5] Several kinds of transition-metal
complexes have proved to be effective with respect to CÀF ac-
tivation.[6] Although some articles that describe CÀF activation
that involves stoichiometric iridium complexes have been pub-
lished,[7] to our knowledge there have been few reports on cat-
alytic CÀF activation with iridium as a catalyst. A typical exam-
ple is the Ir-catalyzed reduction of fluorobenzene with a silane
reagent by Brookhart and Yang.[8a] Other transition metals have
been reported for more complex transformations of CÀF
bonds.[8b]
Scheme 1. Some typical natural and artificial diaryl ethers.
[a] J. Chen, K. Zhao, B. Ge, C. Xu, Dr. D. Wang, Prof. Y. Ding
The Key Laboratory of Food Colloids and Biotechnology
Ministry of Education, School of Chemical and
Material Engineering, Jiangnan University
1800 Lihu Road, Wuxi, Jiangsu Province 214122 (China)
Fax: (+86)510-85917763
Transition-metal-catalyzed CÀO bond coupling from CÀX
bonds and phenolic derivatives has always been useful as
a method for the construction of diaryl ether molecules.[10] Re-
cently, scientists have made great efforts in this area. Various
transition metals (e.g., Fe, Cu, and Pd) have been shown to be
effective in regard to CÀO coupling. Monnier, Taillefer, and
Man et al. reported the efficient and versatile sol–gel immobi-
lized copper catalyst for the Ullmann arylation of phenols.[11]
E-mail: wangdw@jiangnan.edu.cn
yding@jiangnan.edu.cn
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/asia.201403130.
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Yang and Xu et al. reported the coupling reaction with mag-
netic copper–ferrite nanoparticles as catalysts.[12] Bolm and co-
workers reported the FeCl3-catalyzed CÀO coupling of phenols
with aryl iodides;[13] and later Buchwald and Bolm et al. studied
the iron-catalyzed CÀO coupling reaction in the presence of
trace amounts of copper.[14] Similar results have been described
by Likhar et al. using Fe3O4 mesoporouspolyaniline as a cata-
lyst.[15] Concurrently, several other groups (Singh, Olofsson, Zol-
figol, Obora, and so forth) have published their results in this
area.[16] Despite the aforementioned excellent examples, these
reactions usually require high temperatures, harsh conditions,
or expensive starting materials (Scheme 2). Herein, we report
Scheme 3. The strategy of CÀF bond activation by formation of the BÀF
bond.
Result and Discussion
On the basis of our analysis, the reaction of para-cyanfluoro-
benzene was used to test this idea by using B2pin2 as an addi-
tive. Interestingly, the self-coupling product was obtained, al-
though at a low yield. Next, the screening of reaction condi-
tions was performed to obtain a high yield. The experiments
showed that the reaction could be conducted smoothly. The
results are summarized in Table 1. In most cases, moderate to
excellent yields were obtained when [{Ir(cod)Cl}2]/dppe (cod=
cyclooctadiene; dppe=1,2-bis(diphenylphosphino)ethane) was
used as a catalyst in dimethylformamide (DMF) to give 95% of
the product (Table 1, entry 9). A control reaction showed that
the reaction could not occur without the iridium catalyst
(Table 1, entry 20).
Thus, having established the optimal conditions of [{Ir-
(cod)Cl}2] (2 mol%), dppe (4.1 mol%), and Cs2CO3 as the base,
and B2pin2, we explored the scope of the Ir-catalyzed etherifi-
cation reaction. The results were summarized in Table 2. The
reactions were carried out in DMF at 1408C in air. Generally,
Scheme 2. Several methods of synthesis of diaryl ethers.
that iridium-catalyzed CÀF activation has been realiz-
Table 1. Screening of reaction conditions.[a]
ed through the use of bis(pinacolato)diboron (B2pin2)
as a reagent with the formation of the BÀF bond and
homocoupling of aryl fluorides with the incorpora-
tion of an oxygen atom.
Entry
Catalyst[b]
Solvent
Yield [%][c]
We have recently shown that the stoichiometric
CÀF bond activation of a chloro-bridged iridium(III)
dimer, 2-(4,6-difluorophenyl)pyridyl (dfppy), leads to
the formation of a heteroleptic cyclometalated iridiu-
m(III) complex.[17] The point of concern, however, is
whether the iridium complex could be applied effec-
tively as a chemoselective catalyst for CÀF bond acti-
vation. Based on careful consideration, we believe CÀ
F bond activation can be achieved with the help of
reagents that involve Si, P, or B elements.[18] This is
because the formation of the FÀSi bond, FÀP bond,
or BÀF bond is much easier than that of MF (M=
metal).[19] Therefore, we have proposed a possible CÀ
F bond activation through the release of the BÀF
bond (Scheme 3). The oxidative addition of fluoro-
benzene to the iridium catalyst formed the complex
B species,[20] subsequently exchanging with B2pin2 to
form C by releasing the BÀF bond[21] to complete the
CÀF activation.
1
2
3
4
5
6
7
8
[(PPh3)3Ir(CO)H]/PPh3
[(PPh3)3Ir(CO)H]/P(C6H5OCH3)3
[(PPh3)3Ir(CO)H]/P(C4H9)3
[(PPh3)3Ir(CO)H]/dppe
[(PPh3)3Ir(CO)H]/X-Phos
[{Ir(cod)Cl}2]/PPh3
[{Ir(cod)Cl}2]/P(C6H5OCH3)3
[{Ir(cod)Cl}2]/P(C4H9)3
[{Ir(cod)Cl}2]/dppe
[{Ir(cod)Cl}2]/X-Phos
[{Ir(coe)Cl}2]/PPh3
[{Ir(coe)Cl}2]/P(C6H5OCH3)3
[{Ir(coe)Cl}2]/P(C4H9)3
[{Ir(coe)Cl}2]/dppe
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
43
32
25
67
<5
48
34
<5
95
<5
25
20
<5
58
<5
47
<5
<5
62
9
10
11
12
13
14
15
16
17
18
19
20[e]
[{Ir(coe)Cl}2]/X-Phos
[{Ir(cod)Cl}2]/dppe
[{Ir(cod)Cl}2]/dppe
[{Ir(cod)Cl}2]/dppe
[{Ir(cod)Cl}2]/dppe
DMSO
dioxane
toluene
DMA[d]
DMF
none
<5
[a] Conditions: 1a (0.5 mmol), [Ir] (0.02 mmol, 4 mol%), ligand (0.0205 mmol,
4.1 mol%), B2pin2 (0.55 mmol), Cs2CO3 (0.55 mmol, 1.1 equiv), solvent (3 mL), 24 h,
1408C, in air. [b] dppe=1, 2-bis(diphenylphosphino)ethane. X-Phos=2-dicyclohexyl-
phosphino-2’,4’,6’-triisopropylbiphenyl. coe=cyclooctene. [c] Isolated yields, separated
by column chromatography. [d] DMA=N,N-dimethylacetamide. [e] Catalyst was not
added.
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obtained. For example, when nitrochlorobenzene
was used in this reaction, the desired product was
separated with a yield of 82% (Scheme 4).
Table 2. Substrate expansion of simple fluorobenzene.[a]
The diaryl ether compounds could easily be con-
verted into the biphenyl derivative in one step on
the basis of the Suzuki coupling. The reaction pro-
ceeded smoothly in toluene and gave the desired
product with a nearly quantitative yield (Scheme 5).
Fluorine-containing polymers are new types of
multifunctional materials. They have attracted consid-
erable attention on account of their unique proper-
ties, such as low surface energy, low refractive index,
oil and water repellence, and high chemical and ther-
mal stabilities.[23] Thus, fluorinated polymers have
been exploited extensively. Their applications include
electronics, biomaterials, optical devices, and coat-
ings (Scheme 6). With the aforementioned methodol-
ogy, the product (4h) was reduced to the corre-
sponding diamine with a 90% yield. Finally, fluorine-
containing polymers were easily obtained under the
known conditions.[24]
Entry
1
Substrate
Product
Yield [%][b]
95 (2a)
2
3
82 (2b)
88 (2c)
4
trace (2d)
5
6
84 (2e)
80 (2 f)
Macgregor and Braun et al., in 2010, synthesized
a useful, highly reactive rhodium(I)–boryl complex
through the reaction of the [Rh(PEt3)3F] compound
with B2pin2, in which fluoroborane FÀBpin was
formed and easily removed [Eq. (1)].[21]
[a] Conditions: 1 (0.5 mmol), [{Ir(cod)Cl}2] (0.01 mmol, 2 mol%), dppe (0.0205 mmol,
4.1 mol%), B2pin2 (0.55 mmol), Cs2CO3 (0.55 mmol, 1.1 equiv), DMF (3 mL), 24 h,
1408C, in air. [b] Isolated yields based on 1.
We believe the reaction of an iridium compound
with B2pin2 was also possible through formation of
the substrates were converted into the desired products, and
in most cases good to excellent yields were obtained (Table 2).
It should be noted that substrates that contain electron-donat-
ing groups produced disappointing results. Importantly, X-ray
FÀBpin. Therefore, we proposed a reaction mechanism for the
iridium-catalyzed CÀF activation reaction (Scheme 7). Initially,
we proposed the oxidative addition of the iridium catalyst
spectrometry confirmed the structure of diaryl ether (2a,
a known compound; see the Supporting Information).[22]
Numerous publications over the past several decades have
shown that the reaction reactivity of carbon–halogen bonds is
CÀI>CÀBr>CÀCl>CÀF and that transition-metal catalysts
have produced all sorts of coupling reactions. Here, however,
we attempted the etherification reaction of multisubstituted,
halogenated benzene. The results are summarized in Table 3.
When bromo-substituted fluorobenzene was tried in this reac-
tion, the chemoselective product of CÀF bond cleavage was
obtained in high yield (Table 3, entry 2). The same phenomen-
on was found with respect to chloro-substituted fluoroben-
zene (Table 3, entry 4). It is significant that the success in terms
of the high selectivity of CÀF>CÀBr and CÀF>CÀCl provides
new evidence for the strategy of CÀF bond activation by for-
mation of the BÀF bond, because the bond energy of BÀF
(613 kJmolÀ1) is much greater and easier to form than that of
the BÀBr (377 kJmolÀ1) and BÀCl (456 kJmolÀ1) bonds. Accord-
ingly, this method provides an alternative method for CÀF
bond activation by using a boron reagent as an activator.
The etherification reaction of chlorobenzene was also ex-
plored. The reaction could still proceed with moderate yields
Scheme 4. The etherification reaction of chlorobenzene.
Scheme 5. The derivatization reaction of diaryl ether derivatives.
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Next, the control experiments for water were set up. Nothing
of the product was detected with dry DMF as a solvent. Subse-
quent experiments focused on the various ratios of DMF with
water. It was found that excessive or insufficient water wors-
ened the reaction. Thus we determined that the optimal ratio
of DMF with water for this reaction is 300:1 (Table 4, entry 4).
An isotopic labeling experiment was also conducted to sup-
port the hypothesis that water is the source of the oxygen
atom. The reaction of para-cyanofluorobenzene with H218O
was conducted under optimal conditions [Eq. (4)]. Upon com-
pletion of the reaction, the separated product was analyzed by
mass spectrometry and the 18O isotopic-labeled product was
found (see the Supporting Information). On the basis of these
experiments, we suggest that the oxygen of diaryl ether
comes from water.
Scheme 7. The proposed possible mechanism of Ir-catalyzed CÀF activation.
Finally, we propose that the reaction can proceed by means of
a phenol intermediate. Fortunately, the intermediate signal
was tracked in this reaction by means of mass spectrometry.
Importantly, the key intermediate (ArOH) could be separated
by column chromatography on silica gel with a very low yield,
Scheme 6. The synthesis of fluorine-containing polymers.
with fluorobenzene, using B2pin2 to generate the cis-fac-IrIII
complex B species through the release of FÀBpin[21,25] and then
by exchanging organic solvent molecules with water to give
the intermediate C. After reductive elimination, intermediate D
(ArOH) was released (this intermediate could be detected and
separated although resulted in a low yield; see the Supporting
Information). Following the transmetalation of complex B’ spe-
cies with intermediate D (complex B species is written as B for
the sake of clarity; Scheme 7B), the complex E species
was formed. After reductive elimination, intermediate E
gave the product diaryl ether to complete the catalytic
cycle.
1
which was characterized by H and 13C NMR spectroscopy and
mass spectrometry (see the Supporting Information). There-
fore, this is very important proof that is sufficient to support
the proposed idea.
A reaction of para-cyanofluorobenzene with phenol was
conducted under optimal conditions [Eq. (5)] to affirm the pro-
B2pin2 was tested in this reaction [Eq. (2)] to verify
the proposed reaction mechanism. It could not occur in
the absence of B2pin2.
posed intermediate. The results showed that the mixture of
two products was obtained and compound 2a was the major
product, which is very important proof of the phenol inter-
mediate (D) proposed.
Another key point here is the origin of the oxygen atom. Possi-
ble sources include dioxygen, water, the boron reagent, and
the solvent itself. First, the control experiments for air were
conducted. The results showed that the desired product still
could be separated with nearly the same yield even under a ni-
trogen atmosphere [Eq. (3)].
Conclusion
In conclusion, the iridium-catalyzed CÀF activation was ach-
ieved with the help of B2pin2. This strategy has provided a con-
venient method for the conversion of fluoride aromatic com-
pounds into symmetrical diaryl ether compounds. Additionally,
some natural diaryl ether compounds and valuable polymers
could be obtained through this methodology. Moreover, the
chemoselective products of CÀF bond cleavage were obtained
with high yields with the CÀBr and CÀCl bonds remaining.
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Experimental Section
Table 3. Substrate expansion of multisubstituted halogenated benzene.[a]
General Procedure for the Reaction of Fluoroben-
zene
[{Ir(cod)Cl}2], dppe, Cs2CO3, and B2pin2 were added into
a 50 mL Schlenk tube in air. Then a solution of fluoro-
benzene in DMF (3 mL) was added in air. The mixture
was stirred for 24 h at 1408C. Upon completion, the re-
action mixture was dissolved in water, then extracted
with ethyl acetate (3ꢁ15 mL), dried with (MgSO4), and
evaporated to give the residue. The residue was then
purified by column chromatography on silica gel (di-
chloromethane/n-hexane 1:1–1:2) to provide the corre-
sponding product.
Entry
1
Substrate
Product
Yield [%][b]
86 (4a)
2
3
4
90 (4b)
76 (4c)
92 (4d)
Acknowledgements
We gratefully acknowledge financial support of this
work from the National Natural Science Foundation
of China (21371080 and 21401080), the Natural Sci-
ence Foundation of Jiangsu Province (BK20130125),
the 333 Talent Project of Jiangsu Province
(BRA2012165), and the Ministry of Education and the
State Administration of Foreign Experts Affairs for the
111 Project (B13025).
5
82 (4e)
Keywords: arenes
chemoselectivity · homogeneous catalysis · iridium
·
CÀF
activation
·
6
7
8
81 (4 f)
75 (4g)
80 (4h)
[1] For selected reviews, see: a) C.-L. Sun, B.-J. Li, Z.-J. Shi,
Chem. Rev. 2011, 111, 1293–1314; b) T. W. Lyons, M. S. San-
ford, Chem. Rev. 2010, 110, 1147–1169; c) P. B. Arockiam, C.
Bruneau, P. H. Dixneuf, Chem. Rev. 2012, 112, 5879–5918;
d) I. A. I. Mkhalid, J. H. Barnard, T. B. Marder, J. M. Murphy,
J. F. Hartwig, Chem. Rev. 2010, 110, 890–931.
[2] For selected reviews, see: a) H. Amii, K. Uneyama, Chem. Rev.
2009, 109, 2119–2183; b) M. F. Kuehnel, D. Lentz, T. Braun,
Angew. Chem. Int. Ed. 2013, 52, 3328–3348; Angew. Chem.
2013, 125, 3412–3433; c) A. D. Sun, J. A. Love, Dalton Trans.
2010, 39, 10362–10374; d) D. O’Hagan, Chem. Soc. Rev.
2008, 37, 308–319.
[a] Conditions: 3 (0.5 mmol), [{Ir(cod)Cl}2] (0.01 mmol, 2 mol%), dppe (0.0205 mmol,
4.1 mol%), B2pin2 (0.55 mmol), Cs2CO3 (0.55 mmol, 1.1 equiv), DMF (3 mL), 24 h,
1408C, in air. [b] Isolated yields based on 3.
[3] For selected examples, see: a) K. Fuchibe, T. Kaneko, K. Mori,
T. Akiyama, Angew. Chem. Int. Ed. 2009, 48, 8070–8073;
Angew. Chem. 2009, 121, 8214–8217; b) X. Pigeon, M. Ber-
geron, F. Barabꢂ, P. Dubꢂ, H. N. Frost, J.-F. Paquin, Angew.
Chem. Int. Ed. 2010, 49, 1123–1127; Angew. Chem. 2010, 122, 1141–
1145; c) M. F. Kꢃhnel, D. Lentz, Angew. Chem. Int. Ed. 2010, 49, 2933–
2936; Angew. Chem. 2010, 122, 2995–2998; d) G. Haufe, S. Suzuki, H.
Yasui, C. Terada, T. Kitayama, M. Shiro, N. Shibata, Angew. Chem. Int. Ed.
2012, 51, 12275–12279; Angew. Chem. 2012, 124, 12441–12445; e) S.
Yow, S. J. Gates, A. J. P. White, M. R. Crimmin, Angew. Chem. Int. Ed.
2012, 51, 12559–12563; Angew. Chem. 2012, 124, 12727–12731; f) G.
Podolan, D. Lentz, H.-U. Reissig, Angew. Chem. Int. Ed. 2013, 52, 9491–
9494; Angew. Chem. 2013, 125, 9669–9672.
Table 4. The control experiments of DMF with water.[a]
Entry
DMF/H2O (v/v)
Yield [%][b]
1
2
3
4
5
6
dry
1000:1
500:1
300:1
100:1
10:1
<5
26
58
92
40
13
[4] O. Allemann, S. Duttwyler, P. Romanato, K. K. Baldridge, J. S. Siegel, Sci-
ence 2011, 332, 574.
[5] a) Y. Xiong, J. Wu, S. Xiao, J. Xiao, S. Cao, J. Org. Chem. 2013, 78, 4599–
4603; b) K. Mikami, Y. Tomita, Y. Itoh, Angew. Chem. Int. Ed. 2010, 49,
3819–3822; Angew. Chem. 2010, 122, 3907–3910; c) M. Takachi, Y. Kita,
M. Tobisu, Y. Fukumoto, N. Chatani, Angew. Chem. Int. Ed. 2010, 49,
8717–8720; Angew. Chem. 2010, 122, 8899–8902; d) M. Bergeron, T.
Johnson, J.-F. Paquin, Angew. Chem. Int. Ed. 2011, 50, 11112 – 11116 ;
Angew. Chem. 2011, 123, 11308–11312; e) T. Iida, R. Hashimoto, K.
Aikawa, S. Ito, K. Mikami, Angew. Chem. Int. Ed. 2012, 51, 9535–9538;
[a] Conditions: 1a (0.5 mmol), [{Ir(cod)Cl}2] (0.01 mmol, 2 mol%), dppe
(0.0205 mmol, 4.1 mol%), B2pin2 (0.55 mmol), Cs2CO3 (0.55 mmol,
1.1 equiv), DMF (3 mL), 24 h, 1408C, in air. [b] Isolated yields, separated
by column chromatography.
Chem. Asian J. 2014, 00, 0 – 0
www.chemasianj.org
5
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&
&
These are not the final page numbers! ÞÞ

Full Paper
Angew. Chem. 2012, 124, 9673–9676; f) K. Fuchibe, M. Takahashi, J. Ichi-
kawa, Angew. Chem. Int. Ed. 2012, 51, 12059–12062; Angew. Chem.
2012, 124, 12225–12228; g) J. Terao, M. Nakamurab, N. Kambe, Chem.
Commun. 2009, 6011–6013; h) M. Janjetovic, A. M. Trꢄff, T. Ankner, J.
Wettergren, G. Hilmersson, Chem. Commun. 2013, 49, 1826–1828.
[6] a) Z. Chen, C.-Y. He, Z. Yin, L. Chen, Y. He, X. Zhang, Angew. Chem. Int.
Ed. 2013, 52, 5813–5817; Angew. Chem. 2013, 125, 5925–5929; b) D.
Yu, L. Lu, Q. Shen, Org. Lett. 2013, 15, 940–943; c) J.-H. Zhan, H. Lv, Y.
Yu, J.-L. Zhang, Adv. Synth. Catal. 2012, 354, 1529–1541.
[7] Y. P. Yan, P. Feng, Q.-Z. Zheng, Y.-F. Liang, J.-F. Lu, Y. X. Cui, N. Jiao,
Angew. Chem. Int. Ed. 2013, 52, 5827–5831; Angew. Chem. 2013, 125,
5939–5943.
[8] a) J. Yang, M. Brookhart, J. Am. Chem. Soc. 2007, 129, 12656–12657;
b) N. Yoshikai, H. Mashima, E. Nakamura, J. Am. Chem. Soc. 2005, 127,
17978–17979.
2013, 52, 12655–12658; Angew. Chem. 2013, 125, 12887–12890; e) A.
´
Correa, O. Garcꢅa Mancheno, C. Bolm, Chem. Soc. Rev. 2008, 37, 1108–
1117; f) Y. Yuan, I. Thomꢂ, S. H. Kim, D. Chen, A. Beyer, J. Bonnamour, E.
Zuidema, S. Chang, C. Bolm, Adv. Synth. Catal. 2010, 352, 2892–2898;
g) S. L. Buchwald, C. Bolm, Angew. Chem. Int. Ed. 2009, 48, 5586–5587;
Angew. Chem. 2009, 121, 5694–5695.
[15] R. Arundhathi, D. Damodara, Pravin. R. Likhar, Adv. Synth. Catal. 2011,
353, 1591–1600.
[16] For selected examples, see: a) Y. Isomura, T. Narushima, H. Kawasaki, T.
Yonezawab, Y. Obora, Chem. Commun. 2012, 48, 3784–3786; b) N. Jalali-
an, T. B. Petersen, B. Olofsson, Chem. Eur. J. 2012, 18, 14140–14149;
c) M. A. Zolfigol, V. Khakyzadeh, A. R. Moosavi-Zare, A. Rostami, A. Zare,
N. Iranpoor, M. H. Beyzavi, R. Luque, Green Chem. 2013, 15, 2132–2140;
d) N. Jalalian, E. E. Ishikawa, L. F. Silva, Jr., B. Olofsson, Org. Lett. 2011,
13, 1552–1555; e) H. Joshi, K. N. Sharma, A. K. Sharma, O. Prakash, A. K.
Singh, Chem. Commun. 2013, 49, 7483–7485.
[17] For selected papers in our group, see: a) L. Liang, F. Wu, S. L. Zhang,
D. W. Wang, Y. Q. Ding, Z. Z. Zhu, Dalton Trans. 2013, 42, 4539–4543;
b) W. Yang, D. Wang, Q. Song, S. Zhang, Q. Wang, Y. Ding, Organometal-
lics 2013, 32, 4130–4135; c) W. Yang, S. Zhang, Y. Ding, L. Shi, Q. Song,
Chem. Commun. 2011, 47, 5310–5312; d) W. Yang, H. Fu, Q. Song, M.
Zhang, Y. Ding, Organometallics 2011, 30, 77–83.
[18] a) G. Meier, T. Braun, Angew. Chem. Int. Ed. 2009, 48, 1546–1548; Angew.
Chem. 2009, 121, 1575–1577; b) M. Teltewskoi, J. A. Panetier, S. A. Mac-
gregor, T. Braun, Angew. Chem. Int. Ed. 2010, 49, 3947–3951; Angew.
Chem. 2010, 122, 4039–4043; c) M. Ahrens, G. Scholz, T. Braun, E. Kem-
nitz, Angew. Chem. Int. Ed. 2013, 52, 5328–5332; Angew. Chem. 2013,
125, 5436–5440; d) G. Ung, G. Bertrand, Chem. Eur. J. 2012, 18, 12955–
12957.
[19] a) H. Lv, Y. B. Cai, J.-L. Zhang, Angew. Chem. Int. Ed. 2013, 52, 3203–
3207; Angew. Chem. 2013, 125, 3285–3289; b) T. Stahl, H. F. T. Klare, M.
Oestreich, ACS Catal. 2013, 3, 1578–1587.
[9] J.-C. Chen, K. Rajendran, Y.-H. Chang, S.-W. Huang, Y.-T. Chern, J. Appl.
Polym. Sci. 2011, 120, 3159–3170.
[10] For selected examples, see: a) J. Zhang, J. Wu, Y. Xiong, S. Cao, Chem.
Commun. 2012, 48, 8553–8555; b) T. Saitoh, J. Ichikawa, J. Am. Chem.
Soc. 2005, 127, 9696–9697; c) E. Buck, Z. J. Song, D. Tschaen, P. G.
Dormer, R. P. Volante, P. J. Reider, Org. Lett. 2002, 4, 1623–1626; d) B. H.
Lipshutz, J. B. Unger, B. R. Taft, Org. Lett. 2007, 9, 1089–1092; e) A. D.
Sagar, R. H. Tale, R. N. Adude, Tetrahedron Lett. 2003, 44, 7061–7063;
f) Z. Liu, R. C. Larock, Org. Lett. 2004, 6, 99–102; g) N. Xia, M. Taillefer,
Chem. Eur. J. 2008, 14, 6037–6039; h) K. Swapna, S. N. Murthy, M. T.
Jyothi, Y. V. D. Nageswar, Org. Biomol. Chem. 2011, 9, 5978–5988; i) I.
Fukawa, T. Tanabe, T. Dozono, J. Chem. Soc. Perkin Trans. 2 1992, 377–
382.
[11] a) H. J. Cristau, P. P. Cellier, S. Hamada, J. F. Spindler, M. Taillefer, Org. Lett.
2004, 6, 913–916; b) A. Ouali, J.-F. Spindler, H. J. Cristau, M. Taillefer,
Adv. Synth. Catal. 2006, 348, 499–505; c) F. Monnier, M. Taillefer, Angew.
Chem. Int. Ed. 2008, 47, 3096–3099; Angew. Chem. 2008, 120, 3140–
3143; d) F. Monnier, M. Taillefer, Angew. Chem. Int. Ed. 2009, 48, 6954–
6971; Angew. Chem. 2009, 121, 7088–7105; e) A. Tlili, N. Xia, F. Monnier,
M. Taillefer, Angew. Chem. Int. Ed. 2009, 48, 8725–8728; Angew. Chem.
2009, 121, 8881–8884; f) A. Tlili, F. Monnier, M. Taillefer, Chem. Eur. J.
2010, 16, 12299–12302; g) S. Benyahya, F. Monnier, M. Taillefer, M. W. C.
Man, C. Bied, F. Ouazzani, Adv. Synth. Catal. 2008, 350, 2205–2208.
[12] a) S. Yang, W. Xie, H. Zhou, C. Wu, Y. Yang, J. Niu, W. Yang, J. Xu, Tetrahe-
dron 2013, 69, 3415–3418; b) S. Yang, C. Wu, M. Ruan, Y. Yang, Y. Zhao,
J. Niu, W. Yang, J. Xu, Tetrahedron Lett. 2012, 53, 4288–4292; c) S. Yang,
C. Wu, H. Zhou, Y. Yang, Y. Zhao, C. Wang, W. Yang, J. Xu, Adv. Synth.
Catal. 2013, 355, 53–58.
[20] a) T. Ishiyama, J. Takagi, K. Ishida, N. Miyaura, N. R. Anastasi, J. F. Hartwig,
J. Am. Chem. Soc. 2002, 124, 390–391; b) T. A. Boebel, J. F. Hartwig, J.
Am. Chem. Soc. 2008, 130, 7534–7535; c) C. W. Liskey, J. F. Hartwig, J.
Am. Chem. Soc. 2012, 134, 12422–12425.
[21] For the RhÀF exchanges with B2pin2 by release of the BÀF bond, see
Ref. 18b.
[22] A. Dey, G. R. Desiraju, Chem. Commun. 2005, 2486–2488.
[23] a) W. Yang, Y. Chen, D. Han, L. Zhu, J. Fluorine Chem. 2013, 149, 8–12;
b) W. Xu, Q. An, L. Hao, Z. Sun, W. Zhao, Fibers Polym. 2013, 14, 895–
903.
[24] R. Simonutti, A. Mariani, P. Sozzani, S. Bracco, M. Piacentini, S. Russo,
Macromolecules 2002, 35, 3563–3568.
[13] O. Bistri, A. Correa, C. Bolm, Angew. Chem. Int. Ed. 2008, 47, 586–588;
Angew. Chem. 2008, 120, 596–598.
[25] For a Pd-catalyzed F/Cl exchange example, see Ref. 6a.
[14] a) J.-F. Marcoux, S. Doye, S. L. Buchwald, J. Am. Chem. Soc. 1997, 119,
10539–10540; b) C. H. Burgos, T. E. Barder, X. Huang, S. L. Buchwald,
Angew. Chem. Int. Ed. 2006, 45, 4321–4326; Angew. Chem. 2006, 118,
4427–4432; c) L. Salvi, N. R. Davis, S. Z. Ali, S. L. Buchwald, Org. Lett.
2012, 14, 170–173; d) R. Zhu, S. L. Buchwald, Angew. Chem. Int. Ed.
Received: October 4, 2014
Published online on && &&, 0000
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Chem. Asian J. 2014, 00, 0 – 0
www.chemasianj.org
6
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

Full Paper
FULL PAPER
Perfect partners: The iridium-catalyzed
CÀF activation of fluorarenes was ach-
ieved through the use of bis(pinacola-
to)diboron with the formation of the BÀ
F bond and self-coupling. This strategy
provides a convenient method with
which to convert fluoride aromatic com-
pounds into symmetrical diaryl ether
compounds (see scheme).
&
CÀF Activation
Jianping Chen, Keyan Zhao, Bingyang Ge,
Chongying Xu, Dawei Wang,*
Yuqiang Ding*
&& – &&
Iridium-Catalyzed Synthesis of Diaryl
Ethers by Means of Chemoselective
CÀF Bond Activation and the
Formation of BÀF Bonds
Chem. Asian J. 2014, 00, 0 – 0
www.chemasianj.org
7
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
&
These are not the final page numbers! ÞÞ