Diphenyliodonium-Catalyzed Fluorination of Arynes: Synthesis of ortho-Fluoroiodoarenes

Article abstract of DOI:10.1002/anie.201503308

Described is a one-pot vicinal fluorination-iodination of arynes at room temperature. The diphenyliodonium salt proved to be a privileged catalyst for this nucleophilic fluorination process using CsF as a fluorine source, and a subsequent facile electrophilic iodination with C₄F₉I was also found to be crucial to ensure the efficient fluorination. This new synthetic protocol has a broad substrate scope under mild reaction conditions.

Full text of DOI:10.1002/anie.201503308

Angewandte
Chemie
International Edition: DOI: 10.1002/anie.201503308
German Edition: DOI: 10.1002/ange.201503308
Fluorination
Diphenyliodonium-Catalyzed Fluorination of Arynes: Synthesis of
ortho-Fluoroiodoarenes**
Yuwen Zeng, Guangyu Li, and Jinbo Hu*
Abstract: Described is a one-pot vicinal fluorination-iodina-
tion of arynes at room temperature. The diphenyliodonium salt
proved to be a privileged catalyst for this nucleophilic
fluorination process using CsF as a fluorine source, and
a subsequent facile electrophilic iodination with C4F9I was also
found to be crucial to ensure the efficient fluorination. This
new synthetic protocol has a broad substrate scope under mild
reaction conditions.
arynes, direct nucleophilic fluorination of an aryne with FÀ
still remains a challenging task.[7] Indeed, aryne intermediates
are often generated by their o-(trimethylsilyl)aryl triflate
precursors in the presence of excessive amounts of FÀ, but
only in few cases were aryl fluorides detected as byproducts.[8]
In 2008, Grushin et al. found that ArBr could be transformed
into ArF through aryne intermediates [Eq. (1); DMSO =
dimethylsulfoxide, TMAF = tetramethylammonium fluo-
ride].[9] However, this reaction is impractical owing to the
harsh reaction conditions (90–1108C), poor conversion of
ArX, and inseparability of the product from starting materi-
als.
A
ryl fluorides (ArF) have found an increasing number of
applications in pharmaceuticals, agrochemicals, and materials
science, as well as in positron emission tomography (PET).[1]
À
Currently, the formation of Ar F bonds can be achieved by
either transition-metal-free or transition-metal-assisted fluo-
We have recently reported silver-mediated perfluoro-
alkylations of arynes.[10] As a continuing research effort, we
sought to develop a mild nucleophilic fluorination of arynes.
We reasoned that the previous failures in developing
efficient nucleophilic fluorination of arynes may be attributed
to the following reasons: a) arynes are “soft” species[5a] and
reluctant to react with the “hard” FÀ,[1c] and the kinetically
unfavorable fluorination step possesses a much higher energy
barrier (Scheme 1, path A) compared to other pathways.
Actually, in the absence of productive pathways, the highly
reactive aryne intermediates could even react with inert
solvent molecules rather than FÀ.[11] b) ortho-Fluoroaryl
anion intermediates are thermodynamically unstable above
À508C and have been used as excellent aryne precursors since
1940 (Scheme 1, retro-path A).[12]
rination processes using FÀ/F+ reagents.[2–4] However, Ar F
À
bond-formation reactions by nucleophilic fluorination with FÀ
reagents are usually performed at elevated temperatures,
typically higher than 808C.[3a–c] Therefore, new routes for
À
nucleophilic fluorination to form Ar F bonds under mild
reaction conditions have been highly sought after [Eq. (2);
Tf = trifluoromethanesulfonyl, TMS = trimethylsilyl].
To solve these problems, we envisioned that this both
kinetically and thermodynamically unfavorable fluorination
step might be achieved by combining a facile electrophilic
quenching step (Scheme 1, paths B) to give stable ortho-
functionalized aryl fluorides [Eq. (2)]. Thus, a wide range of
electrophiles were screened to see whether fluorination of
benzyne would take place (Table 1). However, the consistent
failures when using many electrophiles, such as C+ (entries 1–
5), N+ (entries 6 and 7), S+ (entries 8 and 9), and X+
Arynes, with their unique structure and extraordinary
reactivity, are particularly attractive in organic synthesis[5] and
for theoretical studies.[6] From a synthetic point of view, the
nucleophilic addition of fluoride anions (FÀ) to arynes would
be a straightforward strategy to synthesize aryl fluorides, and
this process may proceed at ambient temperature or even
lower temperatures. However, among the rich chemistry of
[*] Dr. Y. Zeng, Dr. G. Li, Prof. Dr. J. Hu
Key Laboratory of Organofluorine Chemistry, Shanghai Institute of
Organic Chemistry, Chinese Academy of Sciences
345 Ling-Ling Road, Shanghai 200032 (China)
E-mail: jinbohu@sioc.ac.cn
[**] This work was supported by the National Basic Research Program of
China (2015CB931900, 2012CB821600), the National Natural
Science Foundation of China (21372246, 21421002), Shanghai
Science and Technology program (13QH1402400 and
15XD1504400), and the Chinese Academy of Sciences.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201503308.
Scheme 1. Reaction coordinate diagram for the fluorination of aryne.
Angew. Chem. Int. Ed. 2015, 54, 10773 –10777
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
10773

.
Angewandte
Communications
Table 1: Fluorination of benzyne in the presence of electrophilies.
reagents, and ortho-fluoroiodobenzene was formed in 32%
and 36% yields, respectively, without ortho-diiodobenzene
being observed (entries 15 and 16). In addition, in all cases, no
PhF was observed, and further supports our hypothesis that
a facile quenching process is the precondition for the
nucleophilic fluorination of arynes.
Entry[a]
Electrophile
R
Yield [%][b]
1
2
epoxypropane
PhCHO
CH2CH(OH)CH3
CH(OH)Ph
0
0
3
4
PhCOF
COPh
Et
0
0
À
Et3O+BF4
5
6
7
8
Togni reaÀgent
NO2+BF4À
NO+BF4
PhSSPh
CF3
NO2
NO
SPh
0
0
0
0
9
FSO2CH2CH2SO2F
Selectfluor
NCS
NBS
NIS
SO2R’
0
0
0
0
0
7
32
36
10
11
12
13
14
15
16
F
Cl
Br
I
I
I
Inspired by these results, we then turned our attention to
enhancing the efficiency of this fluorination-iodination pro-
cess. However, simple alteration of the reaction parameters
such as reactants (FÀ source and RfI), temperature, solvent,
and reactant ratio proved to be unfruitful. Then, we analyzed
the reaction mixture and found that RfH was formed in
a comparable yield with the product 3a, thus indicating
a proton abstraction process between the ate complex [Ar-I-
Rf]À and proton sources. Furthermore, deuterium-labeling
experiments revealed that both MeCN and residual H2O are
responsible for this protonation process.[14] Thus, the poor
reaction yields can be attributed to the interference from
ÀOH and ÀCH2CN as nucleophiles.[15,16] To minimize the
influence of these anions, we reasoned that adding 1 equiv-
alent of a Lewis acid may deactivate these anions by forming
donor–acceptor adducts. A series of Lewis acids were then
screened and some of the results are summarized in Table 2.
Metal fluorides or triflates were preferred here because these
ꢀ À
PhC C I
CF3I
n-C4F9I
I
[a] Reaction conditions: 1a (0.1 mmol), CsF (0.4 mmol), electrophile
(0.2 mmol), MeCN (4 mL). [b] Yields were determined by 19F NMR
spectroscopy using PhOCF3 as an internal standard. NBS=N-bromo-
succinimide, NCS=N-chlorosuccinimide, NIS=N-iodosuccinimide.
(entries 10–12) reagents, reminded us that our simple picture
of electrophilic quenching was incomplete. These E+ reagents
either exhibited insufficient reactivity (Scheme 1, path B1) or
showed incompatibility with the reaction system. Thereafter,
we realized that several requirements should be met to give
the desired quenching product. On one hand, the energy
barrier of the quenching step should be lower than that of
retro-fluorination step to prevent the degradation of the
ortho-fluoroaryl anion intermediate (Scheme 1, path B2 and
retro-path A). On the other hand, the added electrophile E+
should not undergo side reactions in the reaction system.
Furthermore, the newly formed NuÀ (resulting from electro-
philic species E-Nu; see Scheme 1) should be an innocent
nucleophile, since the desired fluorination process would not
proceed in the presence of another nucleophile (NuÀ) which
possesses higher nucleophilicity than FÀ. With these consid-
erations in mind, we chose I+ reagents (Table 1, entries 13–16)
as electrophiles because an iodination process such as metal–
iodine exchange may proceed smoothly, even at À1008C,[13]
thus indicating a low activation energy barrier (Scheme 1,
path B2). However, it was found that the highly active
iodination reagents such as N-iodosuccinimide (NIS) and 1-
iodophenylacetylene (Table 1, entries 13 and 14) were prone
to undergoing single-electron transfer (SET) processes
[Eq. (3)] rather than the desired metal–iodine exchange
[Eq. (4)]. The SET pathway was supported by our exper-
imental observation of ortho-diiodobenzene in a large quan-
tity (compared with desired product; determined by GC-MS),
which was derived from a nucleophilic addition of benzyne by
IÀ followed by an electrophilic iodination step. We reasoned
that using a milder iodination reagent could diminish the
tendency of SET during the iodination step. This turned out to
be the case when CF3I and C4F9I were employed as I+
Table 2: Fluorination-iodination of benzyne in the presence of a Lewis
acid.
Entry[a]
Lewis acid
Yield [%][b]
1
2
3
4
5
6
7
8
BF3·THF
MgF2
Zn(OTf)2
AlF3
Fe(OTf)2
TiF4
SbF3
MnF3
In(OTf)3
SnF2
CuOTf
AgOTf
40
42
0
44
0
12
23
40
0
29
0
9
10
11
12
13
14
15
16
0
Ph2I+OTfÀ (2a)
(p-F-Ph)2I+OTfÀ (2b)
Mes2I+OTfÀ (2c)
2a[c]
81
84
79
83
[a] Reaction conditions: 1a (0.1 mmol), CsF (0.4 mmol), C4F9I
(0.2 mmol), Lewis acid (0.1 mmol), MeCN (4 mL). [b] Yields were
determined by 19F NMR spectroscopy using PhF as an internal standard.
[c] 10 mol% of 2a. THF=tetrahydrofuran.
10774 www.angewandte.org
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2015, 54, 10773 –10777

Angewandte
Chemie
Table 3: Scope of fluorination-iodination of arynes.
salts do not introduce new nucleophiles. After a quick
screening, we found that common metal-based Lewis acids
did not give improved results (entries 1–12). The reasons are
complicated, and probably include: 1) poor solubility of metal
fluorides (MFn); 2) undesired side reactions;[17] 3) formation
of stable ate complexes. Gratifyingly, Ph2I+OTfÀ (2a), a non-
metal-based Lewis acid, was found to be a privileged
promoter which afforded the product in 81% yield
(entry 13). This finding is intriguing because although
Ar2I+OTfÀ is known as an electrophilic arylating agent as
well as an oxidant,[ 18] its role as a Lewis acid promoter has
rarely been recognized and utilized.[19] We then tuned the
structure of Ar2I+OTfÀ but did not achieve improved results
(entries 14 and 15). However, we noticed that when the
fluorine-labeled 2b was used as a promoter (entry 14), its
structure remained intact during the course of reaction
(> 98% by 19F NMR spectroscopy), thus indicating that 2b
might be a catalyst.[20] Intrigued by this observation, we
conducted a reaction using a catalytic amount of 2a
(10 mol%), and were delighted to find that the reaction
efficiency was unaffected (entry 16), and it further demon-
strated that Ph2I+OTfÀ acted as a catalyst (rather than an
scavenger of undesired anions such as ÀOH and ÀCH2CN) for
fluorination process.
Entry[a]
1
Substrate (1)
Product (3)
Yield [%][b]
78[c]
2
3
71
70
4
5
6
67
72
50[e]
7
73
The application of this method to various structurally
diverse arynes illustrates its synthetic scope (Table 3). Both
symmetrical (entries 1–6) and unsymmetrical arynes
(entries 7–11) are amenable to this reaction, thus affording
the corresponding products in moderate to good yields.
Remarkably, in most cases of unsymmetrical arynes, complete
regioselectivities were observed (entries 7 and 9–11). Steri-
cally hindered 3,6-dimethylbenzyne also works well in this
transformation. Functional groups such as acetal, ether, and
ketone are all well-tolerated in this reaction (entries 5, 7, 10,
and 11). Additionally, heteroarynes such as indolynes[21] are
also good substrates for this reaction (entries 8–11). It is
worth noting that although the indole heterocycle motif is
present in numerous natural products and medicinal agents,
methods to access benzenoid-substituted iodoles remain
limited.[22] Moreover, our method could not only introduce
fluorine into the benzenoid ring of indoles, but also offer an
excellent handle (the iodine atom) for further functionaliza-
tion (such as cross-coupling reactions).
3ha: 6
3hb: 57
8
9
68[d]
88[d]
10
11
57[e]
[a] Reaction conditions: 1 (0.5 mmol), CsF (2 mmol), C4F9I (1 mmol), 2a
(10 mol%) in MeCN (20 mL). [b] Yield of isolated product. [c] Yield
determined by 19F NMR spectroscopy. [d] 2a (30 mol%). [e] 2a
(50 mol%).
To gain more insight into the role of Ph2I+OTfÀ, we
carried out preliminary mechanistic studies. Initially, we
envisaged that the Lewis acidity of diphenyliodonium might
be responsible for its unique performance. To verify this
hypothesis, we studied the interaction between Ph2I+ and all
possible anions. First, we investigated whether Ph2IAr or
Ph2ICH2CN was involved as a key intermediate in the
formation of desired product. However, such a possibility
was ruled out by control experiments[14] in which these
intermediates were found to be unstable. These observations
are in line with previous studies which showed that triorga-
noiodines are prone to undergoing reductive elimination to
give PhI and PhAr, or undergoing homolysis to give free
radicals, even at low temperatures.[23]
of Ph2I+OTfÀ. These mixtures were then monitored by
1H NMR spectroscopy (Figure 1). In the absence of CsF, the
1H NMR peaks for all aromatic protons exhibited significant
downfield shifts owing to the influence of the highly electron-
deficient iodonium species (Figure 1a). However, upon the
treatment of 0.5 equivalents of CsF, each signal for the phenyl
groups shifted upfield (Figure 1b), and at the same time, the
insoluble CsF dissolved quickly to afford a homogeneous
solution. Moreover, when the ratio of CsF to Ph2I+OTfÀ was
increased to 1:1, the signals continued moving upfield (Fig-
ure 1c). However, in this case, a small portion of undissolved
CsF was found at the bottom of the solution even after
vigorous stirring for 30 minutes, thus indicating that the
We next explored the interaction between Ph2I+ and FÀ.
Various amounts of CsF were added into the CD3CN solution
Angew. Chem. Int. Ed. 2015, 54, 10773 –10777
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org 10775

.
Angewandte
Communications
Scheme 2. Proposed mechanism for diphenyliodonium-catalyzed fluo-
rination of arynes.
Figure 1. 1H NMR monitoring of the interaction between Ph2I+OTfÀ
and CsF in CD3CN at room temperature.
sponding anions (ÀOH and ÀCH2CN). In a noncatalytic
process, these anions, as well as their derivative D,[15] react
with an aryne to generate byproducts (reaction rate: path c >
path a). However, in the presence of Ph2I+OTfÀ, the fluoride
anion coordinates with the soft iodine atom in Ph2I+ to afford
4. The adduct 4 works as a new nucleophilic fluorinating
agent, which possesses higher reactivity toward arynes than
other nucleophiles (reaction rate: path b > path c). Another
beneficial effect may stem from the increased concentration
of fluoride sources in the solution, which is also brought about
by coordination with Ph2I+OTfÀ.
In conclusion, a novel diphenyliodonium-catalyzed and
iodination-promoted nucleophilic fluorination of arynes
under mild reaction conditions has been accomplished. This
process provides a powerful synthetic tool for the one-pot
synthesis of ortho-iodinated aryl fluorides, which are highly
useful compounds for organic synthesis. Diphenyliodonium
plays a crucial catalytic role in the fluorination process by
forming an adduct with CsF. Moreover, the intriguingly new
reactivity exhibited by this new adduct provides a basis for the
further development of other new fluorination processes,
which is currently underway in our laboratory.
Ph2I+OTfÀ solution was saturated with FÀ and the adduct 4
was formed. This outcome is surprising because it indicates
that the newly formed 4 is not the neutral species Ph2IF[24] but
a positively charged ion[25] [Eq. (5)]. Indeed, adding an excess
of CsF (4 equiv) into this saturated solution did not change its
1H NMR spectrum (Figure 1d). Moreover, the fact that only
one set of signals were observed in the spectrum of an
unsaturated solution (Figure 1b) led us to conclude that free
Ph2I+ species are in a fast equilibrium (on the NMR time
scale) with 4 [Eq. (6)], thus all the Ph groups were equivalent
in the spectrum (Figure 1b).[26] Additionally, DOSY (diffu-
sion ordered spectroscopy) experiments have demonstrated
that the phenyl groups in the Ph2I+OTfÀ/CsF (excess) system
possesses a higher degree of aggregation than those in the
fluoride-free Ph2I+OTfÀ system.[14]
Keywords: arynes · fluorine · hypervalent compounds ·
Lewis acids · synthetic methods
How to cite: Angew. Chem. Int. Ed. 2015, 54, 10773–10777
Angew. Chem. 2015, 127, 10923–10927
Although the exact structure of 4 is not clear at present,
we assume that this complex may play a crucial role in the
fluorination of arynes. It was found that when the benzyne
precursor and C4F9I (2 equiv) were added into an unsaturated
solution (4 equiv of CsF in 6 equiv of Ph2I+OTfÀ, thus
indicating there was no free CsF) and stirred at room
temperature, 3a was formed in 81% yield [Eq. (7)]. There-
fore, this novel adduct shows promising fluorinating ability in
[1] a) S. Purser, P. R. Moore, S. Swallow, V. Gouverneur, Chem. Soc.
Rev. 2008, 37, 320; b) S. M. Ametamey, M. Honer, P. A.
Schubiger, Chem. Rev. 2008, 108, 1501; c) K. Uneyama, Organo-
fluorine Chemistry, Blackwell, Oxford, 2006.
À
[2] For an excellent recent review on the Ar F bond formation:
M. G. Campbell, T. Ritter, Chem. Rev. 2015, 115, 612.
À
[3] For selected examples of Ar F bond formation by transition-
metal-free nucleophilic fluorination, see: a) G. Balz, G. Schie-
mann, Ber. Dtsch. Chem. Ges. 1927, 60, 1186; b) H. B. Gottlieb, J.
Am. Chem. Soc. 1936, 58, 532; c) P. Tang, W. K. Wang, T. Ritter,
J. Am. Chem. Soc. 2011, 133, 11482; For selected examples of
À
both aryne generation and Ar F bond formation.
With these results in hand, we propose a plausible
reaction mechanism for this unprecedented and very intrigu-
ing diphenyliodonium-catalyzed fluorination reaction
(Scheme 2). The in situ generated aryne intermediate A
reacts with either CsF (path a) or 4 (path b) to afford an
ortho-fluoroaryl anion B, which is quickly captured by RfI to
give the iodine ate complex C.[13,27] Meanwhile, 4 is readily
regenerated from the adduct 5 and CsF. Subsequent proton
abstraction of C from adventitious water or solvent (MeCN)
produces the desired product, byproduct RfH, and corre-
À
Ar F bond formation by transition-metal-free electrophilic
fluorination: d) J. Deyoung, H. Kawa, R. J. Lagow, J. Chem.
Soc. Chem. Commun. 1992, 811; e) S. Yamada, A. Gavryushin, P.
Knochel, Angew. Chem. Int. Ed. 2010, 49, 2215; Angew. Chem.
2010, 122, 2261.
À
[4] For selected examples of Ar F bond formation by transition-
metal-mediated fluorination, see: a) K. L. Hull, W. Q. Anani,
M. S. Sanford, J. Am. Chem. Soc. 2006, 128, 7134; b) D. A.
Watson, M. Su, G. Teverovskiy, Y. Zhang, J. Garcia-Fortanet, T.
Kinzel, S. L. Buchwald, Science 2009, 325, 1661; c) P. Tang, T.
10776 www.angewandte.org
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2015, 54, 10773 –10777

Angewandte
Chemie
Furuya, T. Ritter, J. Am. Chem. Soc. 2010, 132, 12150; d) A.
Casitas, M. Canta, M. Sola, M. Costas, X. Ribas, J. Am. Chem.
Soc. 2011, 133, 19386; e) P. S. Fier, J. F. Hartwig, J. Am. Chem.
Soc. 2012, 134, 10795; f) W. Liu, X. Y. Huang, M. J. Cheng, R. J.
Nielsen, W. A. Goddard, J. T. Groves, Science 2012, 337, 1322;
g) E. Lee, J. M. Hooker, T. Ritter, J. Am. Chem. Soc. 2012, 134,
17456; h) P. S. Fier, J. W. Luo, J. F. Hartwig, J. Am. Chem. Soc.
2013, 135, 2552; i) P. S. Fier, J. F. Hartwig, Science 2013, 342, 956;
j) Y. Ye, S. D. Schimler, P. S. Hanley, M. S. Sanford, J. Am. Chem.
Soc. 2013, 135, 16292.
Suzuki, Angew. Chem. Int. Ed. 2012, 51, 3368; Angew. Chem.
2012, 124, 3424.
[14] For more details, see the Supporting Information.
[15] CH2CNÀ is known to react with MeCN to form a dimer (trans-3-
amino-2-butenenitrile). See: K. O. Christe, W. W. Wilson, R. D.
Wilson, R. Bau, J.-A. Feng, J. Am. Chem. Soc. 1990, 112, 7619.
[16] Nucleophilic attack of aryne by these anions was confirmed by
observing corresponding byproducts in the reaction mixture. See
the Supporting Information.
[17] a) L. Friedman, J. Am. Chem. Soc. 1967, 89, 3071; b) C. Xie, L.
Liu, Y. Zhang, P. Xu, Org. Lett. 2008, 10, 2393.
[18] a) N. R. Deprez, M. S. Sanford, Inorg. Chem. 2007, 46, 1924;
b) R. J. Phipps, M. J. Gaunt, Science 2009, 323, 1593; c) V. V.
Zhdankin, P. J. Stang, Chem. Rev. 2008, 108, 5299.
[5] a) S. V. Kessar, Comprehensive Organic Synthesis Pergamon,
Oxford, 1991; b) D. PeÇa, D. PØrez, E. Guitiµn, Angew. Chem.
Int. Ed. 2006, 45, 3579; Angew. Chem. 2006, 118, 3659; c) R.
Sanz, Org. Prep. Proced. Int. 2008, 40, 215; d) P. M. Tadross,
B. M. Stoltz, Chem. Rev. 2012, 112, 3550; e) C. M. Gampe, E. M.
Carreira, Angew. Chem. Int. Ed. 2012, 51, 3766; Angew. Chem.
2012, 124, 3829.
[19] Recently, another work using diaryliodoniums as Lewis acids has
been reported, see: Y. Zhang, J. Han, Z.-J. Liu, RSC Adv. 2015, 5,
25485.
[6] a) T. R. Hoye, B. Baire, D. W. Niu, P. H. Willoughby, B. P.
Woods, Nature 2012, 490, 208; b) J. M. Medina, J. L. Mackey,
N. K. Garg, K. N. Houk, J. Am. Chem. Soc. 2014, 136, 15798.
[7] For fluorination by metal–aryne complexes, see: a) K. Wang,
S. Y. Yun, P. Mamidipalli, D. Lee, Chem. Sci. 2013, 4, 3205;
b) P. J. Milner, T. Kinzel, Y. Zhang, S. L. Buchwald, J. Am. Chem.
Soc. 2014, 136, 15757; For fluorination of arynes by insertion into
[20] Ar2I+OTfÀ is known to react with FÀ at elevated temperatures to
give ArF. See: a) A. Shah, V. W. Pike, D. A. Widdowson, J.
Chem. Soc. Perkin Trans. 1 1998, 2043; b) T. L. Ross, J. Ermert,
C. Hocke, H. H. Coenen, J. Am. Chem. Soc. 2007, 129, 8018.
[21] a) S. M. Bronner, K. B. Bahnck, N. K. Garg, Org. Lett. 2009, 11,
1007; b) P. H. Y. Cheong, R. S. Paton, S. M. Bronner, G. Y. J. Im,
N. K. Garg, K. N. Houk, J. Am. Chem. Soc. 2010, 132, 1267.
[22] F. R. de Sa Alves, E. J. Barreiro, C. A. M. Fraga, Mini-Rev. Med.
Chem. 2009, 9, 782.
À
F Sn bonds, see: c) H. Yoshida, R. Yoshida, K. Takaki, Angew.
Chem. Int. Ed. 2013, 52, 8629; Angew. Chem. 2013, 125, 8791; for
fluorination of arynes using Bu4NF(tBuOH)4, see: d) T. Ikawa,
S. Masuda, T. Nishiyama, A. Takagi, S. Akai, Aust. J. Chem. 2014,
67, 475.
[23] a) G. Wittig, K. Clauss, Justus Liebigs Ann. Chem. 1952, 578, 136;
b) F. M. Beringer, L. L. Chang, J. Org. Chem. 1972, 37, 1516.
[24] For the synthesis and application of Ph2IF, see: a) H. J. EmelØus,
H. G. Heal, J. Chem. Soc. 1946, 1126; b) K. Chen, G. F. Koser, J.
Org. Chem. 1991, 56, 5764.
[8] a) A. A. Kolomeitsev, M. Vorobyev, H. Gillandt, Tetrahedron
Lett. 2008, 49, 449; b) V. Diemer, J. S. Garcia, F. R. Leroux, F.
Colobert, J. Fluorine Chem. 2012, 134, 146.
[9] V. V. Grushin, W. J. Marshall, Organometallics 2008, 27, 4825.
[10] a) Y. Zeng, L. Zhang, Y. Zhao, C. Ni, J. Zhao, J. Hu, J. Am.
Chem. Soc. 2013, 135, 2955; b) Y. Zeng, J. Hu, Chem. Eur. J.
2014, 20, 6866.
[11] a) H. Yoshida, Y. Asatsu, Y. Mimura, Y. Ito, J. Ohshita, K.
Takaki, Angew. Chem. Int. Ed. 2011, 50, 9676; Angew. Chem.
2011, 123, 9850; b) M. Jeganmohan, C.-H. Cheng, Chem.
Commun. 2006, 2454; c) D. Niu, T. R. Hoye, Nat. Chem. 2014,
6, 34.
[25] Further quantitative 19F NMR analysis of this saturated solution
showed that the ratio of FÀ and Ph2I+ is about 0.75:1.
[26] B. J. Wang, R. L. Cerny, S. Uppaluri, J. J. Kempinger, S. G.
DiMagno, J. Fluorine Chem. 2010, 131, 1113.
[27] The formation of the ate complex is very facile and even faster
than intramolecular proton abstraction. See: S. Tripathy, R.
LeBlanc, T. Durst, Org. Lett. 1999, 1, 1973.
[12] a) G. Wittig, G. Pieper, G. Fuhrmann, Ber. Dtsch. Chem. Ges.
1940, 73, 1193; b) J. Pawlas, M. Begtrup, Org. Lett. 2002, 4, 2687.
[13] a) H. J. Reich, D. P. Green, N. H. Phillips, J. Am. Chem. Soc.
1989, 111, 3444; b) T. Hamura, Y. Chuda, Y. Nakatsuji, K.
Received: April 12, 2015
Revised: May 13, 2015
Published online: July 23, 2015
Angew. Chem. Int. Ed. 2015, 54, 10773 –10777
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org 10777