3,5-Bis(pentafluorosulfanyl)phenylboronic acid: A new organocatalyst for Conia-ene carbocyclization of 1,3-dicarbonyl compounds having terminal alkynes

Article abstract of DOI:10.1016/j.jfluchem.2012.06.007

3,5-Bis(pentafluorosulfanyl)phenylboronic acid 1 was introduced as an efficient organocatalyst for Conia-ene carbocyclization of 1,3-dicarbonyl compounds having terminal alkynes. A variety of 2-alkynic 1,3-dicarbonyl compounds were smoothly converted to ene-carbocyclization products in moderate to excellent yields. Compared with the reported catalyst, 3-nitro phenylboronic acid, catalyst 1 is slightly better in a non-polar solvent such as toluene and Solkane365mfc (1,1,1,3,3-pentafluorobutane). These results indicate that the SF₅ function can be a lipophilic and sterically demanding alternative to the NO₂ group in catalyst design.

Full text of DOI:10.1016/j.jfluchem.2012.06.007

Journal of Fluorine Chemistry 143 (2012) 204–209
Contents lists available at SciVerse ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
3,5-Bis(pentafluorosulfanyl)phenylboronic acid: A new organocatalyst for
Conia-ene carbocyclization of 1,3-dicarbonyl compounds having terminal alkynes
*
Yu-Dong Yang, Xu Lu, Etsuko Tokunaga, Norio Shibata
Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa-ku, Nagoya 466-8555, Japan
A R T I C L E I N F O
A B S T R A C T
Article history:
3,5-Bis(pentafluorosulfanyl)phenylboronic acid 1 was introduced as an efficient organocatalyst for
Conia-ene carbocyclization of 1,3-dicarbonyl compounds having terminal alkynes. A variety of 2-alkynic
1,3-dicarbonyl compounds were smoothly converted to ene-carbocyclization products in moderate to
excellent yields. Compared with the reported catalyst, 3-nitro phenylboronic acid, catalyst 1 is slightly
better in a non-polar solvent such as toluene and Solkane1365mfc (1,1,1,3,3-pentafluorobutane). These
results indicate that the SF5 function can be a lipophilic and sterically demanding alternative to the NO2
group in catalyst design.
Received 12 April 2012
Received in revised form 1 June 2012
Accepted 5 June 2012
Available online 18 June 2012
Keywords:
Boronic acid
ß 2012 Elsevier B.V. All rights reserved.
Carbocyclization
Conia-ene reaction
Organocatalyst
Pentafluorosulfanyl
1. Introduction
been actively studied next to the simple fluorine-substitution. On
the other hand, the utility of the pentafluorosulfanyl (SF5) group is
Much attention has been focused on the design of high-quality
catalysts, including organocatalysts and organometallic catalysts,
for chemical reactions to synthesize complex molecules [1,2].
Electronic tuning is recognized as one of the most important tools
in catalyst design; in particular, electronegativity and steric effects
are important aspects of the intuitive approach that helps chemists
to understand the nature of catalysts. Among various approaches
available, fluorine substitution on molecules is highly attractive for
this purpose. It is a gross understatement to say that introduction
of fluorine into organic molecules often leads to significant changes
in their physical, chemical and even biological properties, in spite
of its less steric effect. The specific physical and chemical
properties of fluorine within fluorine-containing compounds,
especially its strong electronegativity, lipophilicity and reaction
ability, dramatically differ from those of other halogens and lead to
changes in the interaction between the molecule and components
of the surrounding environment [3]. Fluorine-substitution is a
fundamental strategy for developing novel advanced materials,
pharmaceuticals and agrochemicals. Functional groups such as
trifluoromethyl (CF3) [4], triflyl (SO2CF3) [5], trifluoromethylsulfe-
nyl (SCF3) [6], and trifluoromethoxy (OCF3) [7] groups have also
rather undeveloped. The function of SF5 as an electron-withdraw-
ing group is one of the strongest, as strong as the nitro (NO2) group.
The SF5 function is sterically demanding, chemically and thermally
stable [8]. Outstanding lipophilic properties are often observed
when the SF5 function is incorporated into molecules, which is a
fundamental difference from the NO2 group. These unique
properties of SF5 compounds will show remarkable influences
on physical properties other than those observed with fluorine or
trifluoromethyl groups. Although the introduction of the SF5 group
into organic molecules is a challenge [8b,9], a series of aromatic
compounds with an SF5 function are going to be readily available
thanks to the efforts by Umemoto and UBE America Inc. [8d,10].
Their significant developments in the preparation of SF5-contain-
ing aromatic compounds led to the proposal of many potential
applications in pharmaceuticals [11], agrochemicals [12] and
advanced materials [13]. These facts directed us to use SF5 in
catalyst design. However, to the best of our knowledge, no reports
on the application of these SF5-containing organic compounds in
catalysis had been reported. As a part of our ongoing research
program toward the development of novel synthetic methodolo-
gies in fluorine-related chemistry, we disclose herein the first
performance of an SF5 compound, 3,5-bis(pentafluorosulfanyl)-
phenyl boronic acid (1), in catalysis for Conia-ene carbocyclization
of 1,3-dicarbonyl compounds to provide the desired cyclopentene
derivatives in high yields (Scheme 1).
* Corresponding author. Tel.: +81 52 735 7543; fax: +81 52 735 7543.
E-mail address: nozshiba@nitech.ac.jp (N. Shibata).
0022-1139/$ – see front matter ß 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jfluchem.2012.06.007

Y.-D. Yang et al. / Journal of Fluorine Chemistry 143 (2012) 204–209
205
Scheme 1. 3,5-Bis(pentafluorosulfanyl)phenyl boronic acid 1 effectively catalyzes
Scheme 2. Synthesis of 3,5-bis(pentafluorosulfanyl)phenyl boronic acid 1.
the Conia-ene carbocyclization of 1,3-dicarbonyl compounds having terminal
alkynes.
obtained after 24 h (entry 1). In contrast to this, with 5 mol% of
catalyst 1 in the same condition, substrates 2a–f bearing electron-
donating groups, or not, afforded excellent yields of 3a–f; even the
o-substituted aromatic substrate gave 91% yield of 3c within 48 h
(entries 2–7). On the other hand, for electron-deficient substrates
2g–i, the yields of 3g–i somewhat decreased as the electron-
withdrawing effect was enhanced (entries 8–10). This result
shows that the electron-withdrawing group is not favored under
these conditions. Sterically hindered naphthyl keto-ester 2j also
afforded desired product 3j in 86% yield (entry 11). Furthermore,
aliphatic esters 2k–m also proved to be good substrates and
reacted smoothly. The comparable yields of methyl, ethyl and
isopropyl substrates indicated that the steric effect of the keto
moiety minimally influenced the yield of the reaction (entries 12–
14). In contrast to the keto moiety, the ester moiety had a
significant effect on the reaction. For benzyl ester 2n, 3n was
obtained in 96% after 16 h, but a complex mixture was observed
for tert-butyl ester 2o even after 3 days of stirring (entries 15 and
16). 1,3-Diketones 2p–q could also be efficiently converted to the
desired products 3p–q. In the catalysis of 1, a yield of 75% and 95%
was obtained for methyl and phenyl ketone, respectively (entries
17 and 18).
2. Results and discussion
The carbocyclization of 1,3-dicarbonyl compounds represented
by the Conia-enereaction isoneofthe mostcommonmethodologies
for the formation of five-membered rings which allows cyclopen-
tanes to bear a methylene substituent adjacent to the newly formed
quaternary carbon center [14]. The reaction can be conducted under
thermal conditions, a strong mineral acid, base or metal ion catalysis
[15]. Recently, Dixon et al. reported that arylboronic acids catalyze
the Conia-ene reaction and that acids bearing strong electron-
withdrawing groups on the aromatics afford better reactivity, 3-
nitrobenzeneboronic acid (pKa1 = 6.93) being the most efficient
[15f,16]. However, we experienced poor solubility of 3-nitrobenze-
neboronic acid into some organic solvents such as Solkane1365mfc,
which is an environmentally benign solvent [17]. We then were
interested in using 3,5-bis(pentafluorosulfanyl)phenyl boronic acid
(1)asanalternativecatalyst to3-nitrobenzeneboronicacidduetoits
similar acidity (pKa1 = 5.76) [16] and outstanding solubility in
organic solvents. Based on our calculations, the solubility of 3-nitro
phenylboronic acid (log P: 0.98) in an organic solvent is much lower
than 3,5-bis(pentafluorosulfanyl)phenylboronic acid (log P: 3.6)
[18]. Target compound 1 was easily synthesized from commercially
available 1,3-bis(pentafluorosulfanyl)-5-bromobenzene and tri-
methyl borate (Scheme 2).
The reactivity between catalyst 1 and conventional phenyl-
boronic acid and Dixon’s catalyst, 3-nitro benzeneboronic acid,
was next investigated. While the efficiency of catalysis of 1 was
much higher than that of unactivated benzeneboronic acid (87% vs
25%), similar reactivity was observed for catalyst 1 and 3-nitro
benzeneboronic acid (87% vs 81%) (Scheme 3).
With catalyst 1 in hand, we examined its performance in Conia-
ene carbocyclization using a variety of 1,3-dicarbonyl compounds
2 (Table 1). Without addition of catalyst, only 19% yield of 3a was
We finally examined the Conia-ene carbocyclization in Solk-
ane1365mfc. As shown in Table 2, a yield of 19% was obtained with
catalyst 1 after 24 h, but there was no reaction when 3-nitro
phenylboronic acid was used (Scheme 4). Although the conversion
was low when catalyst 1 was used, its efficiency was higher than 3-
nitro phenylboronic acid in Solkane1365mfc.
Table 1
Compound
compounds
1
catalyzed Conia-ene carbocyclization of acetylenic dicarbonyl
2.a
The possible mechanism is proposed to be similar to Dixon’s
[15f]. First, 1,3-dicarbonyl starting material is promoted to be
enolized by the catalysis of 1. Then a subsequent concerted ene
reaction of this enol form would afford the product (Scheme 5).
.
Entry
2
R1
R2
Time (h)
Yield (%)b
1c
2
2a
2a
2b
2c
2d
2e
2f
–Ph
–OMe
–OMe
–OEt
24
24
40
48
21
58
24
65
72
48
45
3
19
87
70
91
91
71
91
86
75
42
86
86
78
78
96
n.d.
75
95
–Ph
3
–Ph
O
O
O
O
4
-o-Me–Ph
-m-Me–Ph
-p-Me–Ph
-p-OMePh
-p-Br–Ph
-p-Cl–Ph
-p-F–Ph
naphthalene-2-yl
–Me
–OMe
–OMe
–OMe
–OMe
–OMe
–OMe
–OMe
–OMe
–OMe
–OMe
–OMe
–OBn
–OtBu
–Me
5 mol% cat.
5
Ph
OMe
Ph
OMe
6
1 mL toluene, reflux, 24 h
7
8
2g
2h
2i
2a
3a
9
yield: 25% for phenylboronic acid
10
11
12
13
14
15
16
17
18
87% for compound 1
2j
O
O
2k
2l
O
O
5 mol% cat.
–Et
6
Et
OMe
2m
2n
2o
2p
2q
-i-Pr
14
16
72
40
19
Et
OMe
5 mL toluene, reflux, 7h
–Me
–Me
–Ph
2l
3l
–Ph
–Ph
yield: 81% for 3-nitro phenylboronic acid
a
Reaction condition: 0.2 mmol S.M., 1.0 mL dry toluene, reflux.
Isolated yield.
87% for compound 1
b
c
Without addition of catalyst.
Scheme 3. Comparison of efficiency of catalyst 1 and other boronic acids.

206
Y.-D. Yang et al. / Journal of Fluorine Chemistry 143 (2012) 204–209
4.1. Synthesis of 3,5-bis(pentafluorosulfanyl)phenyl boronic acid 1
To a solution of 1,3-bis(pentafluorosulfanyl)-5-bromobenzene
(1.23 g, 3.0 mmol) in THF (4 mL) at À78 8C under nitrogen was
added a solution of i-PrMgBr in Et2O (5.1 mL, 3.6 mmol) dropwise.
The reaction mixture was then allowed to warm to 0 8C and stirred
for 30 min. The subsequent mixture was then added to a solution of
B(OMe)3 (0.5 mL, 4.5 mmol) in THF (6 mL) at À78 8C dropwise.
Warmed it to room temperature and stirred overnight. The
mixture was acidified with aqueous 10% HCl and extracted with
ethyl acetate (3Â 30 mL). The combined organic phase was dried
over anhydrous Na2SO4 and filtered before being concentrated
under reduced pressure. The crude product was purified through
flash chromatography on silica gel (hexane/ethyl acetate = 8/2) to
obtain a white solid (728 mg, yield 65%). 1H NMR (CD3CN,
300 MHz)
Ar–H); 13C NMR (CD3OD, 150.9 MHz)
(overlapping signal, 2C, Ar–C1 and Ar–C4), 153.3 (t, JC–F = 18.1 Hz,
2C, Ar–C); 19F NMR (CD3CN, 282 MHz)
12.4 Hz, 4F), À83.14 (m, 1F); IR (KBr, cmÀ1) 3433, 1604, 1456, 1431,
1360, 1139, 1025, 836, 727; m.p.: >250 8C; GC–MS (EI, m/z) 374
[M]+, 330 [(M+H)-B(OH)2]+, HRMS (EI) calcd. for C6H4F10S2 [(M+H)-
B(OH)2]+: 329.9595, found: 329.9614.
d
6.54 (s, 2H, B(OH)2), 8.31 (m, 1H, Ar–H), 8.38 (s, 2H,
d
125.0 (2C, Ar–C), 134.2
Scheme 4. Comparison of efficiency of
Solkane1365mfc.
1 and 3-nitro phenylboronic acid in
d
À63.57 (dd, J = 148.3,
4.2. General procedure of the Conia-ene carbocyclization of 1,3-
dicarbonyl compounds with alkynes
To a mixture of 1,3-dicarbonyl compounds (2a–q) and 3,5-
bis(pentafluorosulfanyl)phenyl boronic acid (1), dry toluene was
added. The resulting solution was reflux at 120 8C until complete
consumption of the starting materials which was indicated by TLC.
The solvent was then removed under reduced pressure and the
obtained crude product was purified by flash column chromatog-
raphy on silica gel to give the corresponding products (3a–q).
1-Benzoyl-2-methylenecyclopentanecarboxylic acid methyl
ester (3a). Yield = 87%, white solid. 1H NMR was in agreement
Scheme 5. Proposed mechanistic pathway.
3. Conclusion
with the literature [14c]. 1H NMR (CDCl3, 300 MHz)
1H, CCH2CH2( )), 1.84–1.90 (m, 1H, CCH2CH2( )), 2.15–2.24 (m,
1H, CH2CH2( )C55), 2.50–2.54 (m, 2H, COCCH2), 2.80–2.89 (m, 1H,
CH2CH2( )C55), 3.66 (s, 3H, OCH3), 5.19 (s, 1H, 55CH2( )), 5.36 (s,
1H, 55CH2( )), 7.40–7.45 (m, 2H, Ar–H), 7.50–7.56 (m, 1H, Ar–H),
7.82–7.85 (m, 2H, Ar–H); 13C NMR (CDCl3, 150.9 MHz)
24.5
(CCH2CH2), 34.4 (COCCH2), 36.9 (CH2C55), 52.9 (COOCH3), 67.6
(COCCO), 112.1 (C55CH2), 128.6 (2C, Ar–C), 128.9 (2C, Ar–C), 132.9
(Ar–C), 135.4 (Ar–C), 149.1 (C55CH2), 172.5 (COOCH3), 195.3
(C55O); IR (KBr, cmÀ1) 3016, 2975, 2951, 1729, 1681, 1595,
1488, 1453, 1320, 1250, 1159, 1079, 991; m.p.: 82–83 8C; MS (ESI,
m/z) 267 [M+Na]+.
d 1.64–1.81 (m,
In summary, an aromatic pentafluorosulfanyl compound was
applied as an organocatalyst for the first time in the Conia-ene
carbocyclization of 1,3-dicarbonyl compounds. Compared with 3-
nitro phenylboronic acid, catalyst 1 was slightly more efficient in a
non-polar solvent. These results indicate that the SF5 function can
be used as a lipophilic and sterically demanding alternative to the
NO2 group in catalyst design. Further use of 1 for asymmetric
Conia-ene carbocyclization of 1,3-dicarbonyl compounds is under
investigation [19].
a
a
b
b
a
b
d
4. Experimental
1-Benzoyl-2-methylenecyclopentanecarboxylic acid ethyl ester
(3b). Yield = 70%, colorless oil. 1H NMR was in agreement with the
All reactions were performed in oven-dried glassware under a
positive pressure of nitrogen. Solvents were transferred via syringe
and were introduced into the reaction vessels through a rubber
septum. All of the reactions were monitored by thin-layer
chromatography (TLC) carried out on 0.25 mm Merck silica-gel
(60-F254). The TLC plates were visualized with UV light and 7%
phosphomolybdic acid or KMnO4 in water/heat. Column chroma-
tography was carried out on a column packed with silica-gel 60N
literature [14b]. 1H NMR (CDCl3, 300 MHz)
d 1.06 (t, J = 7.2 Hz, 3H,
OCH2CH3), 1.64–1.79 (m, 1H, CCH2CH2(
CCH2CH2( )), 2.14–2.23 (m, 1H, CH2CH2(
COCCH2), 2.81–2.90 (m, 1H, CH2CH2(
COOCH2), 5.22 (s, 1H, 55CH2( )), 5.36 (m, 1H, 55CH2(
J = 7.5 Hz, 2H, Ar–H), 7.50–7.55 (m, 1H, Ar–H), 7.83 (d, J = 7.2 Hz,
2H, Ar–H); 13C NMR (CDCl3, 150.9 MHz)
13.8 (OCH2CH3), 24.4
a
)), 1.81–1.91 (m, 1H,
b
a
)C55), 2.49–2.54 (m, 2H,
b
)C55), 4.07–4.19 (m, 2H,
)), 7.42 (t,
a
b
d
spherical neutral size 63–210
m
m. The 1H NMR (300 MHz), 19F
(CCH2CH2), 34.5 (COCCH2), 36.9 (CH2C55), 61.7 (COOCH2), 67.5
(COCCO), 111.9 (C55CH2), 128.5 (2C, Ar–C), 128.9 (2C, Ar–C), 132.8
(Ar–C), 135.5 (Ar–C), 149.5 (C55CH2), 171.9 (COOCH2), 195.5
(C55O); IR vmax (film)/cmÀ1 2977, 2960, 1733, 1686, 1597, 1580,
1447, 1389,1267, 1021, 887; MS (ESI, m/z) 281 [M+Na]+.
1-(2-methylbenzoyl)-2-methylenecyclopentanecarboxylic acid
methyl ester (3c). Yield = 91%, slightly yellow solid. 1H NMR was in
agreement with the literature [15f]. 1H NMR (CDCl3, 300 MHz)
d
NMR (282 MHz) and 13C NMR (150.9 MHz) spectra for solution in
CDCl3 were recorded on a Buruker-600, a Varian Gemini-300.
Chemical shifts (d) are expressed in ppm downfield from internal
TMS, CHCl3, CD3CN and d4-MeOH. Mass spectra were recorded on a
SHIMADZU GCMS-QP5050A or SHIMAZU LCMS-2010EV (ESI-MS).
The CCl3F was used as internal standard for 19F NMR. Infrared
spectra were recorded on
a
JASCO FT/IR-200 spectrometer.
Anhydrous toluene was distilled over CaH2.
1.64–1.81 (m, 2H, CCH2CH2), 2.20 (dt, J = 13.2, 7.2 Hz, 1H,

Y.-D. Yang et al. / Journal of Fluorine Chemistry 143 (2012) 204–209
207
CH2CH2(
2.66 (dt, J = 12.9, 6.0 Hz, 1H, CH2CH2(
5.24 (t, J = 1.8 Hz, 1H, 55CH2( )), 5.35 (t, J = 1.8 Hz, 1H, 55CH2(
7.16 (t, J = 7.5 Hz, 1H, Ar–H), 7.25–7.34 (m, 3H, Ar–H); 13C NMR
(CDCl3, 150.9 MHz) 20.9 (Ar–CH3), 24.3 (CCH2CH2), 34.4
(COCCH2), 37.0 (CH2C55), 52.8 (COOCH3), 69.9 (COCCO), 112.7
(C55CH2), 125.2 (Ar–C), 126.5 (Ar–C), 130.5 (Ar–C), 131.8 (Ar–C),
137.6 (Ar–C), 137.9 (Ar–C), 149.3 (C55CH2), 172.1 (COOCH3), 201.3
(C55O); IR (KBr, cmÀ1) 2976, 2948, 1731, 1677, 1648, 1599, 1455,
1247, 1074, 908; m.p.: 53–54 8C; MS (ESI, m/z) 281 [M+Na]+.
1-(3-Methylbenzoyl)-2-methylenecyclopentanecarboxylic ac-
id methyl ester (3d). Yield = 91%, white solid. 1H NMR was in
a
)C55), 2.40 (s, 3H, Ar–CH3), 2.43–2.52 (m, 2H, COCCH2),
)C55), 3.64 (s, 3H, OCH3),
)),
1645, 1584, 1452, 1267, 1081, 991; m.p.: 54–56 8C (lit. [15f] 75–
77 8C); MS (ESI, m/z) 345 [M+Na]+.
1-(4-Chlorobenzoyl)-2-methylenecyclopentanecarboxylic acid
methyl ester (3h). Yield = 75%, white semi-solid. 1H NMR (CDCl3,
b
a
b
d
300 MHz)
CCH2CH2(
d
1.65–1.79 (m, 1H, CCH2CH2(
a
)), 1.82–1.91 (m, 1H,
)C55), 2.48–
)C55),
)), 5.36 (s, 1H, 55CH2( )),
7.40 (d, J = 9.0 Hz, 2H, Ar–H), 7.78 (d, J = 8.4 Hz, 2H, Ar–H); 13C NMR
(CDCl3, 150.9 MHz) 24.4 (CCH2CH2), 34.3 (COCCH2), 36.8
b
)), 2.15 (dt, J = 13.2, 6.9 Hz, 1H, CH2CH2(a
2.53 (m, 2H, COCCH2), 2.85 (dt, J = 13.2, 6.6 Hz, 1H, CH2CH2(
3.67 (s, 3H, OCH3), 5.18 (s, 1H, 55CH2(
b
a
b
d
(CH2C55), 52.9 (COOCH3), 67.8 (COCCO), 112.2 (C55CH2), 128.9
(2C, Ar–C), 130.3 (2C, Ar–C), 133.6 (Ar–C), 139.3 (Ar–C), 149.2
(C55CH2), 172.3 (COOCH3), 194.1 (C55O); IR (KBr, cmÀ1) 2953, 1736,
1687, 1572, 1487, 1247, 1158, 884; MS (ESI, m/z) 301 [M+Na]+,
HRMS (ESI) calcd. for C15H15ClNaO3 [M+Na]+: 301.0607, found:
301.0607.
1-(4-Fluorobenzoyl)-2-methylenecyclopentanecarboxylic acid
methyl ester (3i). Yield = 42%, colorless oil. 1H NMR was in
agreement with the literature [14c]. 1H NMR (CDCl3, 300 MHz)
d
agreement with the literature [15f]. 1H NMR (CDCl3, 300 MHz)
1.63–1.74 (m, 1H, CCH2CH2( )), 1.76–1.92 (m, 1H, CCH2CH2( )),
2.18 (dt, J = 13.2, 6.9 Hz, 1H, CH2CH2( )C55), 2.41 (s, 3H, Ar–CH3),
2.48–2.53 (m, 2H, COCCH2), 2.83 (dt, J = 13.2, 6.9 Hz, 1H,
CH2CH2( )C55), 3.66 (s, 3H, OCH3), 5.18 (s, 1H, 55CH2( )), 5.35
(s, 1H, 55CH2( )), 7.29–7.35 (m, 2H, Ar–H), 7.58 (d, J = 7.5 Hz, 1H,
Ar–H), 7.68 (s, 1H, Ar–H);13C NMR (CDCl3, 150.9 MHz)
21.5 (Ar–
d
a
b
a
b
a
b
d
CH3), 24.4 (CCH2CH2), 34.4 (COCCH2), 36.9 (CH2C55), 52.8
(COOCH3), 67.6 (COCCO), 112.0 (C55CH2), 125.9 (Ar–C), 128.3
(Ar–C), 129.5 (Ar–C), 133.6 (Ar–C), 135.3 (Ar–C), 138.5 (Ar–C),
149.5 (C55CH2), 172.5 (COOCH3), 195.4 (C55O); IR (KBr, cmÀ1) 2972,
2951, 1730, 1683, 1648, 1599, 1453, 1274, 1150, 905; m.p.: 41–
43 8C; MS (ESI, m/z) 281 [M+Na]+.
1.67–1.78 (m, 1H, CCH2CH2(
2.12–2.19 (m, 1H, CH2CH2( )C55), 2.51 (t, J = 7.5 Hz, 2H, COCCH2),
2.81 (dt, J = 13.2, 6.9 Hz, 1H, CH2CH2( )C55), 3.67 (s, 3H, OCH3),
5.18 (s, 1H,55CH2( )), 5.36 (s, 1H,55CH2( )), 7.10 (t, J = 8.7 Hz, 2H,
Ar–H), 7.87 (dd, J = 8.9, 5.7 Hz, 2H, Ar–H); 13C NMR (CDCl3,
150.9 MHz) 24.5 (CCH2CH2), 34.4 (COCCH2), 36.9 (CH2C55), 52.9
a)), 1.79–1.93 (m, 1H, CCH2CH2(b)),
a
b
a
b
d
1-(4-Methylbenzoyl)-2-methylenecyclopentanecarboxylic ac-
id methyl ester (3e). Yield = 71%, slightly yellow solid. 1H NMR
was in agreement with the literature [14c]. 1H NMR (CDCl3,
(COOCH3), 67.5 (COCCO), 112.2 (C55CH2), 115.8 (d, JC–F = 21.0 Hz,
2C, Ar–C), 131.5 (Ar–C), 131.6 (d, JC–F = 9.0 Hz, 2C, Ar–C), 149.3
(C55CH2), 165.5 (d, JC–F = 253.5 Hz, Ar–C), 172.4 (COOCH3), 193.8
(C55O); IR vmax (film)/cmÀ1 2954, 2877, 1738, 1682, 1651, 1598,
1506, 1240, 1157, 1083, 850; MS (ESI, m/z) 285 [M+Na]+.
300 MHz)
d
1.63–1.76 (m, 1H, CCH2CH2(
a
)), 1.78–1.92 (m, 1H,
)C55), 2.40 (s,
CCH2CH2(
b
)), 2.18 (dt, J = 13.2, 7.2 Hz, 1H, CH2CH2(a
3H, Ar–CH3), 2.48–2.53 (m, 2H, COCCH2), 2.83 (dt, J = 13.2, 6.6 Hz,
1H, CH2CH2( )C55), 3.66 (s, 3H, OCH3), 5.18 (s, 1H, 55CH2( )), 5.35
(s, 1H, 55CH2( )), 7.22 (d, J = 7.8 Hz, 2H, Ar–H), 7.74 (d, J = 8.1 Hz,
2H, Ar–H); 13C NMR (CDCl3, 150.9 MHz)
21.7 (Ar–CH3), 24.4
(CCH2CH2), 34.4 (COCCH2), 37.0 (CH2C55), 52.8 (COOCH3), 67.5
(COCCO), 111.9 (C55CH2), 129.1 (2C, Ar–C), 129.3 (2C, Ar–C), 132.6
(Ar–C), 143.7 (Ar–C), 149.5 (C55CH2), 172.6 (COOCH3), 194.8
(C55O); IR (KBr, cmÀ1) 2950, 1730, 1680, 1605, 1571, 1430,
1250, 1159, 995; m.p.: 42–44 8C; MS (ESI, m/z) 281 [M+Na]+.
1-(4-Methoxybenzoyl)-2-methylenecyclopentanecarboxylic
acid methyl ester (3f). Yield = 91%, colorless oil. 1H NMR was in
1-(2-Naphthoyl)-2-methylenecyclopentanecarboxylic
methyl ester (3j). Yield = 86%, white solid. 1H NMR was in
agreement with the literature [14c]. 1H NMR (CDCl3, 300 MHz)
1.61–1.79 (m, 1H, CCH2CH2( )), 1.84–1.94 (m, 1H, CCH2CH2( )),
2.29 (m, 1H, CH2CH2( )C55), 2.56 (t, J = 6.6 Hz, 2H, COCCH2), 2.94
(dt, J = 19.8, 6.6 Hz, 1H, CH2CH2( )C55), 3.66 (s, 3H, OCH3), 5.23 (s,
1H, 55CH2( )), 5.39 (s, 1H, 55CH2( )), 7.51–7.62 (m, 2H, Ar–H),
7.84–7.95 (m, 4H, Ar–H), 8.35 (s, 1H, Ar–H); 13C NMR (CDCl3,
150.9 MHz) 24.5 (CCH2CH2), 34.5 (COCCH2), 37.2 (CH2C55), 52.9
(COOCH3), 67.8 (COCCO), 112.2 (C55CH2), 124.8 (Ar–C), 126.9 (Ar–
C), 127.8 (Ar–C), 128.4 (Ar–C), 128.7 (Ar–C), 129.8 (Ar–C), 130.5
(Ar–C), 132.6 (Ar–C), 132.7 (Ar–C), 135.4 (Ar–C), 149.6 (C55CH2),
172.7 (COOCH3), 195.3 (C55O); IR (KBr, cmÀ1) 2980, 2953, 1731,
1676, 1454, 1281, 1125, 997; m.p.: 97–98 8C; MS (ESI, m/z) 317
[M+Na]+.
acid
b
b
a
d
d
a
b
a
b
a
b
d
agreement with the literature [15f]. 1H NMR (CDCl3, 300 MHz)
1.66–1.80 (m, 1H, CCH2CH2( )), 1.82–1.89 (m, 1H, CCH2CH2( )),
2.18 (dt, J = 13.2, 7.5 Hz, 1H, CH2CH2( )C55), 2.47–2.53 (m, 2H,
COCCH2), 2.83 (dt, J = 13.2, 6.6 Hz, 1H, CH2CH2( )C55), 3.67 (s, 3H,
COOCH3), 3.86 (s, 3H, Ar–OCH3), 5.18 (t, J = 2.4 Hz, 1H, 55CH2( )),
5.35 (t, J = 2.1 Hz, 1H,55CH2( )), 6.90 (d, J = 9.0 Hz, 2H, Ar–H), 7.82
(d, J = 9.0 Hz, 2H, Ar–H); 13C NMR (CDCl3, 150.9 MHz)
24.4
d
a
b
a
b
a
1-Acetyl-2-methylenecyclopentanecarboxylic acid methyl es-
ter (3k). Yield = 86%, colorless oil. 1H NMR was in agreement with
b
d
the literature [14b]. 1H NMR (CDCl3, 300 MHz)
d
1.65–1.80 (m, 2H,
CCH2CH2), 2.15–2.24 (m, 4H, partly overlapping signal, CH3CO and
CH2CH2( )C55), 2.36–2.48 (m, 3H, partly overlapping signal,
COCCH2 and CH2CH2( )C55), 3.75 (s, 3H, OCH3), 5.23 (t,
J = 1.8 Hz, 1H, 55CH2), 5.30 (t, J = 1.8 Hz, 1H, 55CH2); 13C NMR
(CDCl3, 150.9 MHz) 24.2 (CCH2CH2), 26.7 (CH3CO), 34.0
(CCH2CH2), 34.4 (COCCH2), 37.0 (CH2C55), 52.8 (COOCH3), 55.5
(Ar–OCH3), 67.4 (COCCO), 111.9 (C55CH2), 113.8 (2C, Ar–C), 127.9
(Ar–C), 131.3 (2C, Ar–C), 149.6 (C55CH2), 163.2 (Ar–C), 172.7
(COOCH3), 193.8 (C55O); IR vmax (film)/cmÀ1 2953, 1733, 1680,
1601, 1575, 1457, 1252, 1158, 1027, 844; MS (ESI, m/z) 297
[M+Na]+.
a
b
d
(COCCH2), 35.1 (CH2C55), 52.8 (COOCH3), 70.5 (COCCO), 112.3
(C55CH2), 148.8 (C55CH2), 171.8 (COOCH3), 203.7 (C55O); IR vmax
(film)/cmÀ1 2955, 1742, 1716, 1648, 1434, 1310, 1263, 1065, 833;
MS (ESI, m/z) 205 [M+Na]+.
1-(4-Bromobenzoyl)-2-methylenecyclopentanecarboxylic acid
methyl ester (3g). Yield = 86%, white solid. 1H NMR was in
agreement with the literature [15f]. 1H NMR (CDCl3, 300 MHz)
d
1.66–1.79 (m, 1H, CCH2CH2(
2.15 (dt, J = 13.2, 6.9 Hz, 1H, CH2CH2(
COCCH2), 2.82 (dt, J = 13.2, 6.6 Hz, 1H, CH2CH2(
OCH3), 5.18 (s, 1H, 55CH2( )), 5.36 (s, 1H, 55CH2(
J = 8.4 Hz, 2H, Ar–H), 7.70 (d, J = 8.7 Hz, 2H, Ar–H); 13C NMR (CDCl3,
150.9 MHz) 24.4 (CCH2CH2), 34.3 (COCCH2), 36.8 (CH2C55), 52.9
(COOCH3), 67.5 (COCCO), 112.3C55CH2), 128.1 (Ar–C), 130.4 (2C,
Ar–C), 131.9 (2C, Ar–C), 134.1 (Ar–C), 149.2 (C55CH2), 172.2
(COOCH3), 194.3 (C55O); IR (KBr, cmÀ1) 2972, 2953, 1730, 1690,
a
)), 1.82–1.91 (m, 1H, CCH2CH2(
)C55), 2.51 (t, J = 7.2 Hz, 2H,
)C55), 3.67 (s, 3H,
)), 7.57 (d,
b
)),
2-Methylene-1-propionylcyclopentanecarboxylic acid methyl
ester (3l). Yield = 78%, colorless oil. 1H NMR was in agreement with
a
b
the literature [15f]. 1H NMR (CDCl3, 300 MHz)
d
1.07 (t, J = 7.5 Hz,
3H, CH2CH3), 1.66–1.79 (m, 2H, CCH2CH2), 2.15–2.24 (m,1H,
CH2CH2( )C55), 2.36–2.56 (m, 4H, partly overlapping signal,
CH2CH3 and COCCH2), 2.58–2.67 (m, 1H, CH2CH2( )C55), 3.74 (s,
3H, OCH3), 5.21 (s, 1H, 55CH2( )), 5.29 (s, 1H, 55CH2(
)); 13C NMR
(CDCl3, 150.9 MHz) 8.6 (CH2CH3), 24.2 (CCH2CH2), 32.3 (CH2CH3),
34.0 (COCCH2), 35.2 (CH2C55), 52.7 (COOCH3), 70.3 (COCCO), 112.2
a
b
a
d
b
a
b
d

208
Y.-D. Yang et al. / Journal of Fluorine Chemistry 143 (2012) 204–209
References
(C55CH2), 148.8 (C55CH2), 171.9 (COOCH3), 206.7 (C55O); IR vmax
(film)/cmÀ1 2954, 2879, 1742, 1715, 1648, 1456, 1376, 1265, 1192,
1075, 1007, 897; MS (ESI, m/z) 219 [M+Na]+.
1-Isobutyryl-2-methylenecyclopentanecarboxylic acid methyl
ester (3m). Yield = 78%, colorless oil. 1H NMR was in agreement
[1] (a) M.T. Reetz, B. List, S. Jaroch, H. Weinmann (Eds.), Organocatalysis, Springer,
Berlin, 2008;
(b) B. List (Ed.), Topics in Current Chemistry. Vol. 291: Asymmetric Organocata-
lysis, Springer, Berlin, 2010;
with the literature [15f]. 1H NMR (CDCl3, 300 MHz)
d
1.07 (d,
)), 1.10 (d, J = 6.9 Hz, 3H, CH(CH3)2( )),
1.65–1.78 (m, 2H, CCH2CH2), 2.22–2.31 (m, 1H, CH2CH2( )C55),
2.35–2.48 (m, 3H, partly overlapping signal, COCCH2 and
CH2CH2( )C55), 2.98 (m, 1H, CH(CH3)2), 3.75 (s, 3H, OCH3), 5.24
(s, 1H, 55CH2( )), 5.30 (s, 1H, 55CH2(
)); 13C NMR (CDCl3,
150.9 MHz) 20.7 (1C, CH(CH3)2( )), 20.8 (1C, CH(CH3)2( )),
(c) D. Enders, O. Niemeier, A. Henseler, Chemical Reviews 107 (2007) 5605–5655.
[2] (a) F. Glorius (Ed.), Topics in Organometallic Chemisty. Vol. 21: N-heterocyclic
Carbenes in Transition Metal Catalysis, Springer, Berlin, 2007;
(b) T. Ikariya, M. Shibasaki (Eds.), Topics in Organometallic Chemisty. Vol. 37:
Bifunctional Molecular Catalysis, Springer, Berlin, 2011;
J = 6.6 Hz, 3H, CH(CH3)2(
a
b
a
(c) M.C. Willis, Chemical Reviews 110 (2010) 725–748;
b
(d) J.H. Xie, S.F. Zhu, Q.L. Zhou, Chemical Reviews 111 (2011) 1713–1760.
[3] (a) R. Filler, Y. Kobayashi, L.M. Yagupolskii (Eds.), Organofluorine Compounds in
Medicinal Chemistry and Biomedical Applications, Elsevier, Amsterdam/New
York, 1993;
(b) P. Krisch, Modern Fluoroorganic Chemistry, Wiley-VCH, Weinheim, 2004;
(c) J.A. Ma, D. Cahard, Chemical Reviews 108 (2008) PR1–PR43.
[4] (a) J. Song, Y. Wang, L. Deng, Journal of the American Chemical Society 128 (2006)
6048–6049;
a
b
d
a
b
24.1 (CCH2CH2), 33.9 (COCCH2), 34.7 (CH2C55), 37.5 (CH(CH3)2),
52.6 (COOCH3), 71.0 (COCCO), 112.5 (C55CH2), 148.4 (C55CH2),
171.8 (COOCH3), 210.3 (C55O); IR vmax (film)/cmÀ1 2970, 2875,
1744, 1715, 1647, 1458, 1380, 1264, 1191, 964, 899; MS (ESI, m/z)
233 [M+Na]+.
(b) B.G. Shearer, R.W. Wiethe, A. Ashe, A.N. Billin, J.M. Way, T.B. Stanley, C.D.
Wagner, R.X. Xu, L.M. Lessnitzer, R.V. Merrihew, T.W. Shearer, M.R. Jeune, J.C.
Ulrich, T.M. Willson, Journal of Medicinal Chemistry 53 (2010) 1857–1861;
(c) H. Xie, Y. Zhang, S. Zhang, X. Chen, W. Wang, Angewandte Chemie Interna-
tional Edition 50 (2011) 11773–11776;
(d) N.A. Tamayo, Y. Bo, V. Gore, V. Ma, B. Nishimura, P. Tang, H. Deng, L. Klionsky,
S.G. Lehto, W. Wang, B. Youngblood, J. Chen, T.L. Correll, M.D. Bartberger, N.R.
Gavva, M.H. Norman, Journal of Medicinal Chemistry 55 (2012) 1593–1611.
1-Acetyl-2-methylenecyclopentanecarboxylic acid benzyl es-
ter (3n). Yield = 96%, colorless oil. 1H NMR was in agreement with
the literature [15f]. 1H NMR (CDCl3, 300 MHz)
d
1.67–1.79 (m, 2H,
CCH2CH2), 2.17 (s, 3H, CH3CO), 2.18–2.24 (m, 1H, CH2CH2( )C55),
2.38–2.47 (m, 3H, partly overlapping signal, COCCH2 and
CH2CH2( )C55), 5.18 (s, 2H, OCH2Ph), 5.21 (t, J = 2.1 Hz, 1H,
55CH2( )), 5.28 (t, J = 1.8 Hz, 1H,55CH2( )), 7.28–7.39 (m, 5H, Ar–
H); 13C NMR (CDCl3, 150.9 MHz)
24.2 (CCH2CH2), 26.7 (CH3CO),
a
`
[5] (a) L. Porres, O. Mongin, C. Katan, M. Charlot, T. Pons, J. Mertz, M. Blanchard-
b
Desce, Organic Letters 6 (2004) 47–50;
(b) D. Nakashima, H. Yamamoto, Journal of the American Chemical Society 128
(2006) 9626–9627;
(c) M. Rueping, W. Ieawsuwan, A.P. Antonchick, B.J. Nachtsheim, Angewandte
Chemie International Edition 46 (2007) 2097–2100;
(d) C.M. Park, M. Bruncko, J. Adickes, J. Bauch, H. Ding, A. Kunzer, K.C. Marsh, P.
Nimmer, A.R. Shoemaker, X. Song, S.K. Tahir, C. Tse, X. Wang, M.D. Wendt, X. Yang,
H. Zhang, S.W. Fesik, S.H. Rosenberg, S.W. Elmore, Journal of Medicinal Chemistry
51 (2008) 6902–6915.
a
b
d
34.1 (COCCH2), 35.1 (CH2C55), 67.3 (COCCO), 70.5 (OCH2Ph), 112.4
(C55CH2), 128.3 (Ar–C), 128.4 (2C, Ar–C), 128.6 (2C, Ar–C), 135.5
(Ar–C), 148.6 (C55CH2), 171.1 (COOCH3), 203.4 (C55O); IR vmax
(film)/cmÀ1 3033, 2958, 2878, 1738, 1648, 1498, 1455, 1434,
1230, 1140, 1083, 992; MS (ESI, m/z) 281 [M+Na]+.
[6] (a) A.B. Beeler, D.K. Schlenk, J.M. Rimoldi, Tetrahedron Letters 42 (2001) 5371–
5372;
1-(1-Benzoyl-2-methylenecyclopentyl)ethanone
Yield = 75%, slightly yellow solid. 1H NMR was in agreement
with the literature [15f]. 1H NMR (CDCl3, 300 MHz)
1.70–1.86
(m, 2H, CCH2CH2), 2.17–2.28 (m, 4H, partly overlapping signal,
COCH3 and CH2CH2( )C55), 2.44–2.58 (m, 2H, COCCH2), 2.74 (dt,
J = 13.5, 6.6 Hz, 1H, CH2CH2( )C55), 5.12 (t, J = 2.1 Hz, 1H,
55CH2( )), 5.41 (t, J = 2.1 Hz, 1H, 55CH2( )), 7.42 (m, 2H, Ar–
H), 7.50–7.55 (m, 1H, Ar–H), 7.76–7.79 (m, 2H, Ar–H); 13C NMR
(CDCl3, 150.9 MHz) 24.3 (CCH2CH2), 27.3 (COCH3), 34.4
(3p).
(b) G. Heywang, B. Baasner, A. Marhold, W. Pauluus, P. Reinecke, H.G. Schmitt, US
Patent 4,778,511 (1988).;
d
(c) S. Okui, N. Kyomura, T. Fukuchi, K. Tanaka, US Patent 6,335,357 (2002).
[7] (a) K.J. Hodgetts, P. Ge, T. Yoon, S.D. Lombaert, R. Brodbeck, M. Gulianello, A.
Kieltyka, R.F. Horvath, J.H. Kehne, J.E. Krause, G.D. Maynard, D. Hoffman, Y. Lee, L.
Fung, D. Doller, Journal of Medicinal Chemistry 54 (2011) 4187–4206;
(b) H.R. Chobanian, Y. Guo, P. Liu, M. Chioda, T.J. Lanza Jr., L. Chang, T.M. Kelly, Y.
Kan, O. Palyha, X.M. Guan, D.J. Marsh, J.M. Metzger, J.N. Gorski, K. Raustad, S.P.
Wang, A.M. Strack, R. Miller, J. Pang, M. Madeira, K. Lyons, J. Dragovic, M.L.
Reitman, R.P. nargund, L.S. Lin, ACS Medicinal Chemistry Letters 3 (2012) 252–
256.
a
b
a
b
d
(COCCH2), 35.9 (CH2C55), 75.5 (COCCO), 113.3 (C55CH2), 128.5
(2C, Ar–C), 129.4 (2C, Ar–C), 132.9 (Ar–C), 135.5 (Ar–C), 149.1
(C55CH2), 198.1 (PhCOC), 204.6 (COCH3); IR (KBr, cmÀ1) 2964,
1693, 1595, 1579, 1447, 1239, 1132, 903; m.p.: 40–41 8C; MS
(ESI, m/z) 251 [M+Na]+.
[8] (a) P. Kirsch, The petafluorosulfuranyl group and related structures, in: Modern
Fluoroorganic Chemistry, Wiley-VCH, Weinheim, 2004, pp. 146–156;
(b) W.A. Sheppard, Journal of the American Chemical Society 84 (1962) 3064–
3072;
(c) T. Umemoto, L.M. Garrick, N. Saito, Beilstein Journal of Organic Chemistry 8
(2012) 461–471;
(d) UBE America Inc. Aromatic SF5 derivatives. http://www.ube.com/ArSF5.html
(accessed April 2012).
(2-Methylenecyclopentane-1,1-diyl)bis(phenylmethanone)
(3q). Yield = 95%, slightly yellow solid. 1H NMR (CDCl3, 300 MHz)
d
[9] (a) A.M. Sipyagin, C.P. Bateman, Y.T. Tan, J.S. Thrasher, Journal of Fluorine
Chemistry 112 (2001) 287–295;
1.80–1.85 (m, 2H, CCH2CH2), 2.61–2.69 (m, 4H, partly overlapping
signal, COCCH2 and CH2CH2C55), 4.96 (d, J = 2.1 Hz, 1H, 55CH2( )),
5.39 (d, J = 2.1 Hz, 1H, 55CH2( )), 7.31–7.36 (m, 4H, Ar–H), 7.41–
7.47 (m, 2H, Ar–H), 7.79–7.82 (m, 4H, Ar–H); 13C NMR (CDCl3,
150.9 MHz) 23.6 (CCH2CH2), 34.9 (COCCH2), 37.7 (CH2C55), 73.6
(b) A.M. Sipyagin, V.S. Enshov, S.A. Kashtanov, C.P. Bateman, B.D. Mullen, Y.T. Tan,
J.S. Thrasher, Journal of Fluorine Chemistry 125 (2004) 1305–1316;
(c) R.W. Winter, G.L. Gard, Journal of Fluorine Chemistry 125 (2004) 549–552.
[10] (a) T. Umemoto, WO Patent WO/2008/118787 (2008);
(b) T. Umemoto, US Patent 7,592,491 (2009);
a
b
d
(c) T. Umemoto, US Patent 7,820,864 (2010);
(COCCO), 113.4 (C55CH2), 128.5 (4C, Ar–C), 129.6 (4C, Ar–C), 132.8
(2C, Ar–C), 136.0 (2C, Ar–C), 150.4 (C55CH2), 198.2 (2C, PhCOC); IR
(KBr, cmÀ1) 2957, 1679, 1646, 1578, 1447, 1235, 1183, 889; m.p.:
86–88 8C; MS (ESI, m/z) 313 [M+Na]+, HRMS (ESI) calcd. for
(d) T. Umemoto, US Patent 7,851,646 (2010);
(e) T. Umemoto, US Patent 0,130,790 (2010);
(f) T. Umemoto, WO Patent WO/2010/033930 (2010).
[11] (a) T. Mo, X. Mi, E.E. Milner, G.S. Dow, P. Wipf, Tetrahedron Letters 51 (2010)
5137–5140;
C
20H18NaO2 [M+Na]+: 313.1204, found: 313.1216.
(b) J.M. Coteron, M. Marco, J. Esquivias, X. Deng, K.L. White, J. White, M. Koltun,
F.E. Mazouni, S. Kokkonda, K. Katneni, R. Bhamidipati, D.M. Shackleford, I. Angulo-
Barturen, S.B. Ferrer, M.B. Jime´nez-Dı´az, F.J. Gamo, J.N. Burrow, P.K. Rathod, S.A.
Charman, M.A. Phillips, Journal of Medicinal Chemistry 54 (2011) 5540–5561;
(c) D. Andeotti, A. Checchia, D. Hamprecht, F. Micheli, WO Patent WO/2006/
108700 (2006).
Acknowledgements
[12] (a) P.J. Crowley, G. Mitchell, R. Salmon, P.A. Worthington, Chimia 58 (2004) 138–
142;
This study was financially supported in part by Grants-in-Aid
for Scientific Research (24105513, 22106515, Project No. 2304).
We thank Dr. Max Braun, Solvay Fluor GmbH for the generous gift
of Solkane1 365mfc. We also thank Ube America for support in
part. E.T. acknowledges Grants-in-Aid for Scientific Research for
financial support (23915014).
(b) D.S. Lim, J.S. Choi, C.S. Pak, J.T. Welch, Journal of Pesticide Science 32 (2007)
255–259;
(c) R.T. Chern, J.R. Zingerman, J.N. Clark, M.D. Drag, WO Patent WO/1999/047139
(1999);
(d) Y. Matsuzaki, M. Morimoto, S. Fujioka, M. Tohnishi, WO Patent WO/2003/
093228 (2003).

Y.-D. Yang et al. / Journal of Fluorine Chemistry 143 (2012) 204–209
209
[13] (a) P. Kirsch, M. Bremer, M. Heckmeier, K. Tarumi, Angewandte Chemie Interna-
tional Edition 38 (1999) 1989–1992;
(e) C.L. Deng, T. Zou, Z.Q. Wang, R.J. Song, J.H. Li, Journal of Organic Chemistry 74
(2009) 412–414;
(b) P.G. Nixon, R. Winter, D.G. Castner, N.R. Holcomb, D.W. Grainger, G.L. Gard,
Chemistry of Materials 12 (2000) 3108–3112;
(f) M. Li, T. Yang, D.J. Dixon, Chemical Communications 46 (2010) 2191–
2193.
(c) C. Ye, G.L. Gard, R.W. Winter, R.G. Syvret, B. Twamley, J.M. Shreeve, Organic
Letters 9 (2007) 3841–3844.
[16] ACD/pKa dB, version 12.01, Advanced Chemistry Development, Inc., Toronto, ON,
Canada, 2009, www.acdlabs.com.
[14] (a) B.K. Corkey, F.D.A. Toste, Journal of the American Chemical Society 125 (2005)
17168–17169;
[17] (a) A. Kusuda, H. Kawai, S. Nakamura, N. Shibata, Greem Chemistry 11 (2009)
1733–1735;
(b) Q. Gao, B.F. Zheng, J.H. Li, D. Yang, Organic Letters 7 (2005) 2185–2188;
(c) T. Yang, A. Ferrali, F. Sladojevich, L. Campbell, D.J. Dixon, Journal of the
American Chemical Society 131 (2009) 9140–9141;
(b) A. Kusuda, X.H. Xu, X. Wang, E. Tokunaga, N. Shibata, Greem Chemistry 13
(2011) 843–846;
(c) X.H. Xu, A. Kusuda, E. Tokunaga, N. Shibata, Greem Chemistry 13 (2011)
46–50.
(d) W. Li, X. Liu, X. Zhou, C.S. Lee, Organic Letters 12 (2010) 548–551.
[15] (a) G. Eglinton, M.C. Whiting, Journal of the Chemical Society (1953) 3052–3059;
(b) J.M. Conia, P. Le Perchec, Synthesis (1975) 1–19;
[18] ACD/LogP dB, version 12.01, Advanced Chemistry Development, Inc., Toronto,
ON, Canada, 2009, www.acdlabs.com.
(c) M.A. Boaventura, J. Drouin, J.M. Conia, Synthesis (1983) 801–804;
(d) J.J. Kenney-Smith, S.T. Staben, F.D. Toste, Journal of the American Chemical
Society 126 (2004) 4526–4527;
[19] S. Suzuki, E. Tokunaga, D.S. Reddy, T. Matsumoto, M. Shiro, N. Shibata, Ange-
wandte Chemie International Edition 51 (2012) 4131–4135.