Nucleophilic fluoroalkylation of epoxides with fluorinated sulfones

Article abstract of DOI:10.1021/jo060955l

The unprecedented nucleophilic fluoroalkylation of simple epoxides with fluorinated sulfones was achieved to give the β-fluoroalkyl alcohols in one step. The negative "fluorine effect" in the nucleophilic fluoroalkylation of epoxides with fluorinated carbanions was probed by the reactivity comparison between carbanions PhSO₂CF₂ ^- (3) and PhSO₂CCl₂^- (4) and between carbanions PhSO₂CHF^- (7) and PhSO₂CHCl ^- (13). The mediation of this fluorine effect by introducing another electron-withdrawing benzenesulfonyl group was found to be an effective way to significantly increase the nucleophilicity of the fluorinated carbanions, with the reactivity order [(PhSO₂)₂CF^-] (16) > PhSO₂CFH^- (7) ? PhSO₂CF₂ ^- (3).

Full text of DOI:10.1021/jo060955l

Nucleophilic Fluoroalkylation of Epoxides with Fluorinated Sulfones
Chuanfa Ni, Ya Li, and Jinbo Hu*
Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy
of Sciences, 354 Fenglin Road, Shanghai 200032, China
jinbohu@mail.sioc.ac.cn
ReceiVed May 8, 2006
The unprecedented nucleophilic fluoroalkylation of simple epoxides with fluorinated sulfones was achieved
to give the â-fluoroalkyl alcohols in one step. The negative “fluorine effect” in the nucleophilic
fluoroalkylation of epoxides with fluorinated carbanions was probed by the reactivity comparison between
-
-
-
-
carbanions PhSO
2 2 2 2 2 2
CF (3) and PhSO CCl (4) and between carbanions PhSO CHF (7) and PhSO CHCl
(13). The mediation of this fluorine effect by introducing another electron-withdrawing benzenesulfonyl
group was found to be an effective way to significantly increase the nucleophilicity of the fluorinated
-
-
-
carbanions, with the reactivity order [(PhSO
2 2
)
CF ] (16) > PhSO
2
CFH (7) . PhSO
2
CF
2
(3).
Introduction
SCHEME 1
Nucleophilic fluoroalkylation, such as tri-, di-, monofluoro-
methylation, and perfluoroalkylation, typically involving the
-
transfer of a fluorine-bearing carbanion (Rf ) to an electrophile,
has been widely studied and applied to synthesize fluorine-
containing materials and bioactive molecules.1 However,
despite the availability of a variety of good methods (e.g., using
-7
8
the Ruppert-Prakash reagent ) and numerous examples of
nucleophilic fluoroalkylation of various substrates (such as
aldehydes, ketones, imines, nitrones, enones, indanones, esters,
lactones, cyclic anhydrides, oxazolidinones, amides, imides,
azirines, nitroso compounds, sulfur-based electrophiles, thio-
cyanates, selenocyanates, alkyl triflates, and alkyl halides, among
(
1) (a) Prakash, G. K. S.; Yudin, A. K. Chem. ReV. 1997, 97, 757-786.
1
,2
(
(
b) Prakash, G. K. S.; Mandal, M. J. Fluorine Chem. 2001, 112, 123-131.
c) Prakash, G. K. S.; Hu, J. New Nucleophilic Fluoroalkylation Chemistry.
others), the nucleophilic fluoroalkylation of simple epoxides
9
-11
still remains a challenging task (Scheme 1).
In Fluorine-Containing Synthons; Soloshonok, V. A., Ed.; American
Chemical Society: Washington, DC, 2005. (d) Prakash, G. K. S.; Hu, J.
Trihalomethyl Compounds. In Science of Synthesis; Charette, A. B., Ed.;
Thieme: New York, 2005; Vol. 22.
Nucleophilic fluoroalkylation of epoxides, i.e., an oxacycle
ring-opening reaction of epoxides with the fluorine-bearing
-
carbanion (Rf ), is synthetically attractive for synthesizing
(
(
(
2) Singh, R. P.; Shreeve, J. M. Tetrahedron 2000, 56, 7613-7632.
â-fluoroalkyl alcohols 1 in one step (Scheme 1). Dolbier and
3) Langlois, B. R.; Billard, T. Synthesis 2003, 185-194.
4) Ait-Mohand, S.; Takechi, N.; Medebielle, M.; Dolbier, W. R., Jr.
Org. Lett. 2001, 3, 4271-4273.
5) McClinton, M. A.; McClinton, D. A. Tetrahedron 1992, 48, 6555-
666.
(9) Takechi, N.; Ait-Mohand, S.; Medebielle, M.; Dolbier, W. R., Jr.
Org. Lett. 2002, 4, 4671-4672.
(
6
(10) Ozouf, P.; Binot, G.; Pommelet, J.-C.; Lequeux, T. P. Org. Lett.
2004, 6, 3747-3750.
(
6) Burton, D. J.; Yang, Z. Y. Tetrahedron 1992, 48, 189-275.
(
7) (a) Ni, C.; Hu, J. Tetrahedron Lett. 2005, 46, 8273-8277. (b) Li,
(11) We noticed that in 2005 Roeschenthaler et al. briefly presented in
a symposium poster that a perfluoroethyl anion can react with simple
epoxides in the presence of a TiCl4 catalyst, but unfortunately, no
documented details of the reactions are available. Roeschenthaler, G. V.;
Y.; Hu, J. Angew. Chem., Int. Ed. 2005, 44, 5882-5886. (c) Li, Y.; Ni, C.;
Liu, J.; Zhang, L.; Zheng, J.; Zhu, L.; Hu, J. Org. Lett. 2006, 8, 1693-
1
696.
th
(8) (a) Ruppert, I.; Schlich, K.; Volbach, W. Tetrahedron Lett. 1984,
Kolomeitsev, A.; Barten, J. Poster Presentation. Presented at 17 Interna-
2
5, 2195-2198. (b) Prakash, G. K. S.; Krishnamuti, R.; Olah, G. A. J. Am.
tional Symposium of Fluorine Chemistry, Shanghai, China, July 24-29,
2005; Paper P-I-14.
Chem. Soc. 1989, 111, 393-395.
1
0.1021/jo060955l CCC: $33.50 © 2006 American Chemical Society
Published on Web 08/05/2006
J. Org. Chem. 2006, 71, 6829-6833
6829

Ni et al.
TABLE 1. (Benzenesulfonyl)dichloromethylation of Epoxides
-
co-workers reported that a trifluoromethyl anion (CF3 ) derived
from a CF3I/TDAE reagent could not undergo productive
reaction with styrene oxide, either alone or in the presence of
9
Lewis acids such as TiCl4, BF3, or BPh3. Lequeux et al.
-
generated phosphonodifluoromethyl carbanion 2 ((EtO)2(O)PCF2 )
both from diethyl difluoromethanephosphonate (HCF2P(O)-
(OEt)2) with LDA and from diethyl bromodifluoromethane-
phosphonate with alkyllithium, and they found that in both cases
the carbanion 2 could not effectively react with propylene oxide
1
0
even in the presence of the Lewis acid catalyst BF3-Et2O.
To the best of our knowledge, the only successful example
related to nucleophilic fluoroalkylation of epoxides in the
literature is the reaction between phosphonodifluoromethyl
carbanion 2 (generated from diisopropyl methylsulfanyldifluoro-
methylphosphonate and tert-butyllithium) and epoxides in the
1
0,11
presence of BF3-Et2O, providing moderate product yields.
The unusual difficulty of the ring-opening reaction between
an epoxide and a fluorine-bearing carbanion, although not fully
understood, arguably can be attributed to the intrinsic property
-
of the fluorine-bearing carbanion (Rf ), i.e., its low thermal
stability (caused by its high tendency to undergo R-elimination
of a fluoride ion due to the electron repulsion between the
electron pairs on the small fluorine atom(s) and the electron
lone pair occupying the p-orbital of the carbanion center) as
well as its weak nucleophilicity toward epoxides. We surmised
that the possible solution to this problem is to apply a proper
auxiliary group connecting to the fluorinated carbanion to
increase its thermal stability and nucleophilicity toward ep-
oxides. The benzenesulfonyl group (PhSO2) is one of the
choices, for its good ability to stabilize and soften fluorinated
carbanions and its varying chemical reactivities (e.g., easy to
remove via reductive desulfonylation).7 Herein, as part of our
ongoing effort to prepare â-fluoroalkyl alcohols for further
elaborations, we wish to disclose the studies toward the
nucleophilic fluoroalkylation of epoxides with fluorinated
carbanions bearing the benzenesulfonyl functionality.
a
Isolated yield. b The yields were obtained without further optimization.
,12
good nucleophilicity even toward alkyl halides and imines.7b,12a
To understand the unusual inertness of carbanion 3 toward
epoxides, we studied the reactivity of the chlorinated analogue
benzenesulfonyl)dichloromethyl anion 4 (PhSO2CCl2 ) that was
-
(
generated from dichloromethyl phenyl sulfone and n-butyl-
lithium. The data are summarized in Table 1.
Results and Discussion
To our surprise, under similar reaction conditions, (benzene-
sulfonyl)dichloromethyl anion 5 readily reacted with a variety
of epoxides to provide the products 6 with good regioselectivity
Attempted Reaction with (Benzenesulfonyl)difluoromethyl
and (Benzenesulfonyl)dichloromethyl Anions. First, we ex-
amined the nucleophilic fluoroalkylation of epoxides with
(reacting at the less hindered site of the epoxide) and high yields
(see Table 1). The striking reactivity difference between the
(benzenesulfonyl)difluoromethyl anion 3 and (benzenesulfonyl)-
-
(
benzenesulfonyl)difluoromethyl anion 3 (PhSO2CF2 ). Unfor-
7,12
tunately, carbanion 3 generated in situ from PhSO2CF2H and
a base (LHMDS or t-BuOK) in THF at -78 °C would not react
with propylene oxide, and after the regular workup, the starting
materials were recovered. Addition of a Lewis acid such as
BF3-Et2O did not lead to any improvement of the reaction.
The carbanion 3 was also generated from both PhSO2CF2Br/
dichloromethyl anion 5 indicates a remarkable negatiVe fluorine
effect accounting for the low reactivity of 3 toward epoxides.
Reaction with the (Benzenesulfonyl)monofluoromethyl
Anion. On the basis of the above studies, we turned our interest
to the nucleophilic fluoroalkylation of epoxides with (benzene-
n
t
BuLi and PhSO2CF2SCH3/ BuLi systems, but in both cases,
-
sulfonyl)monofluoromethyl anion 7 (PhSO2CHF ), assuming
the generated anion 3 would not react with propylene oxide
even in the presence of the BF3-Et2O catalyst. These results
were particularly interesting given the facts that the nonfluori-
that the less fluorine-substituted carbanion 7 would have better
nucleophilicity than 3. The carbanion 7 can be generated from
monofluoromethyl phenyl sulfone and a base, and its reactions
-
nated (benzenesulfonyl)methyl anion 5 (PhSO2CH2 ) can readily
with carbonyl compounds, alkyl halides, and imines have been
react with epoxides13 and that anion 3 itself is known to have
7c,14
reported previously.
Thus, we carefully optimized the
experimental conditions of the reaction between PhSO2CFH2/
base and propylene oxide (see Table 2) and found that Et2O is
the best solvent (although THF is also suitable, the yield is
(
12) (a) Prakash, G. K. S.; Hu, J.; Wang, Y.; Olah, G. A. Angew. Chem.,
Int. Ed. 2004, 43, 5203-5206. (b) Prakash, G. K. S.; Hu, J.; Mathew, T.;
Olah, G. A. Angew. Chem., Int. Ed. 2003, 42, 5216-5219. (c) Prakash, G.
K. S.; Hu, J.; Wang, Y.; Olah, G. A. Org. Lett. 2004, 6, 4315-4317. (d)
Prakash, G. K. S.; Hu, J.; Wang, Y.; Olah, G. A. Eur. J. Org. Chem. 2005,
(14) (a) Inbasekaran, M.; Peet, N. P.; McCarthy, J. R.; LeTourneau, M.
E. J. Chem. Soc., Chem. Commun. 1985, 678-679. (b) Nakamura, T.; Guha,
S. K.; Ohta, Y.; Abe, D.; Ukaji, Y.; Inomata, K. Bull. Chem. Soc. Jpn.
2002, 75, 2031-2041.
2
218-2223.
13) Trost, B. M.; Chadiri, M. R. J. Am. Chem. Soc. 1984, 106, 7260-
261.
(
7
6830 J. Org. Chem., Vol. 71, No. 18, 2006

Nucleophilic Fluoroalkylation of Epoxides
TABLE 2. Survey of the Reaction Conditions
TABLE 3. (Benzenesulfonyl)monofluoromethylation of Epoxides
Lewis acid
molar ratio yield
entrya base (11)
solvent
Et2O
Et2O
(12)
(8/9/11/12) (%)b
1
2
3
4
5
6
n-BuLi
n-BuLi
LiHMDS Et2O-HMPA
n-BuLi THF-HMPA
LiHMDS Et2O
n-BuLi Et2O
BF3-Et2O
BF3-Et2O
-
1:2:1.2:2
1:2:2:2
1:2:2:-
1:2:2:-
1:2:2:2
1:2:2:2
67
78
68
59
0
-
c
BF3-Et2O
TiCl4
68
a
Typical reaction conditions: into the mixture of sulfone 7 and solvent
was added base at -78 °C, and the reaction mixture was stirred for 30
min, followed by addition of Lewis acid and propylene oxide subsequently.
b
c
Isolated yield. Sulfone 8, epoxide, and Lewis acid were first mixed, into
which base was added.
somehow low) and that in the presence of BF3-Et2O the
addition of 2 equiv of n-BuLi is necessary to ensure the good
product yield (see Table 2, entry 2). n-Butyllithium worked as
a better base than lithium hexamethyldisilazide (LiHMDS)
(entries 3 and 5), and the addition of HMPA or TiCl4 did not
significantly improve the product yield (entries 3, 4, and 6).
With the optimized reaction conditions (Table 2, entry 2), we
examined the scope of this new nucleophilic ring-opening
reaction of epoxides with carbanion 7. The results are sum-
marized in Table 3. In all cases, the reactions were found to be
highly regioselective with the fluorinated carbanion 7 attacking
the less-hindered sites of epoxides. For alkyl monosubstituted
epoxides, the reaction provided satisfactory to good product
yields (Table 3, entries 1 and 2). However, the reaction yields
dropped in the cases of aryl monosubstituted and other disub-
stituted epoxides (entries 3-7). These results indicate that the
monofluoro-substituted carbanion 7 has better nucleophilicity
than (benzenesulfonyl)difluoromethyl anion 3 for the ring-
opening reaction with epoxides. For comparison, the nucleo-
philic addition reactions of epoxides with monochlorine-
a
Isolated yields. b When the ratio of epoxide/7/ BuLi was 1:1.5:1.6,
n
-1
the isolated yield was 48%. c The yield was determined by F NMR using
PhCF as the internal standard.
19
3
TABLE 4. (Benzenesulfonyl)monochloromethylation of Epoxides
-
substituted carbanion 13 (PhSO2CHCl ) were also studied (see
Table 4). As expected, the reactions between epoxides and
(benzenesulfonyl)monochloromethyl anion 13 (generated from
monochloromethyl phenyl sulfone 14 and a base) gave better
product yields than those with (benzenesulfonyl)monofluoro-
methyl anion 7, confirming that the fluorine substitution of a
carbanion will decrease the latter’s nucleophilicity (negative
fluorine effect).
Reaction with the Bis(benzenesulfonyl)monofluoromethyl
Anion. To further increase the nucleophilicity of a fluorinated
carbanion toward epoxides, we tried to attach two benzene-
sulfonyl groups to the fluorine-bearing carbanion, i.e., to study
the reactivity of bis(benzenesulfonyl)monofluoromethyl anion
-
1
6 ([(PhSO2)2CF ], generated from bis(benzenesulfonyl)mono-
fluoromethane 17 and a base). Because the benzenesulfonyl
functionality is able to delocalize the electron density from the
carbanion center, bis(benzenesulfonyl) substitution on a fluori-
nated carbanion can thus increase its stability and nucleophilicity
by diminishing the electron repulsion between the electron pairs
on the small fluorine atom and the electron lone pair occupying
the p-orbital of the carbanion center.
The initial attempt to prepare bis(benzenesulfonyl)mono-
fluoromethane 17 ((PhSO2)2CHF) through the reaction of
PhSO2CH2F/n-BuLi with PhSSPh (or PhSO2SPh) was not
a
Isolated yield.
successful (Scheme 2). After a quick screening of different
preparation methods, finally we were able to obtain compound
17 in 48% yield via an electrophilic fluorination reaction of
bis(benzenesulfonyl)methane with Selectfluor (see Table 5).
J. Org. Chem, Vol. 71, No. 18, 2006 6831

Ni et al.
SCHEME 2
SCHEME 3
TABLE 5. Preparation of Bis(benzenesulfonyl)fluoromethane
yield (%)a
both PhSO2CF2- (3) and PhSO2CFH- (7), and the benzene-
sulfonyl group(s) played a very important role in mediating the
negative fluorine effect and tuning the reactivity order 16 > 7
entry
base
solvent
temp
-78 °C to rt 32 20
t-BuOH rt 39
DMF rt 48 not determined
17
19
1
2
3
LiHDMS (1equiv) THF
t-BuOK (1equiv)
t-BuOK (1equiv)
0
.
3. It should be mentioned that the reactions between 16 and
epoxides were highly regioselective (see Table 6, entries 1, 2,
and 4-6), except the reaction with styrene oxide that gave two
regioisomers 20c and 20d, which is probably caused by the
electron-withdrawing nature of the benzene ring (entry 3).
Considering that aziridines usually have a reactivity similar
to epoxides, we extended our nucleophilic fluoroalkylation
chemistry with aziridine 21 (Scheme 3). The reaction between
a
Isolated yield.
TABLE 6. Bis(benzenesulfonyl)monofluoromethylation of Epoxides
-
carbanion PhSO2CHF (7, generated from PhSO2CHF and
n-BuLi) and aziridine 21 was not successful, and an unidentified
complex mixture was obtained. However, the similar reaction
-
between 21 and [(PhSO2)2CF ] (16) was found to be rewarding,
and the fluoroalkylated amine 22 was obtained in 69% isolated
yield (Scheme 3).
Conclusions
The unprecedented nucleophilic fluoroalkylation of simple
epoxides with fluorinated sulfones was achieved to give the
â-fluoroalkyl alcohols in one step. The negative “fluorine effect”
in the nucleophilic fluoroalkylation of epoxides with fluorinated
carbanions was probed by a reactivity comparison between
-
-
carbanions PhSO2CF2 (3) and PhSO2CCl2 (4) and between
-
-
carbanions PhSO2CHF (7) and PhSO2CHCl (13). The media-
tion of this fluorine effect with the introduction of another
electron-withdrawing benzenesulfonyl group was found to be
an effective way to significantly increase the nucleophilicity of
-
the fluorinated carbanions, with the reactivity order [(PhSO2)2CF ]
16) > PhSO2CFH (7) . PhSO2CF2 (3). These interesting
-
-
(
results provide an insight into the nucleophilic fluoroalkylation
chemistry, and this new methodology promises to be a useful
tool for synthetic chemists.
Experimental Section
(Benzenesulfonyl)dichloromethylation of Epoxides. n-Butyl-
lithium in hexane (2.4 mmol) was added into the THF (10 mL)
solution of dichloromethyl phenyl sulfone (450 mg, 2.0 mmol) at
-
78 °C, and after 30 min at that temperature, BF
3
2
-Et O (0.30
mL, 2.4 mmol) was added followed by the addition of propylene
oxide (0.28 mL, 4.0 mmol). The reaction mixture was stirred at
temperatures ranging from -78 °C to room temperature for another
2
h then quenched by the addition of 5 mL of saturated sodium
a
bicarbonate solution. The reaction mixture was extracted with
diethyl ether, and the ether phase was washed with brine. After
drying over anhydrous magnesium sulfate and solvent removal, the
crude product was further purified by flash chromatography using
silica gel.
Isolated yield.
With compound 17 in hand, we carried out the fluoroalkyl-
ation reaction of epoxides with bis(benzenesulfonyl)mono-
fluoromethyl anion 16. The results are as shown in Table 6.
The product yields of the reaction range from good to excellent,
indicating that the bis(benzenesulfonyl)-substituted carbanion
(PhSO2)2CF ] (16) possesses much better nucleophilicity than
1
-Benzenesulfonyl-1,1-dichloro-3-butanol (6a). 73% yield,
1
colorless oil. H NMR (CDCl
2.85 (m, 2H), 4.46 (md, J ) 6.6, 2.6 Hz, 1H), 7.63 (m, 2H), 7.80
3
): δ 1.36 (d, J ) 6.5 Hz, 3H), 2.63-
-
13
[
3
(m, 1H), 8.10 (m, 2H). C NMR (CDCl ): δ 24.2, 48.1, 64.8,
6832 J. Org. Chem., Vol. 71, No. 18, 2006

Nucleophilic Fluoroalkylation of Epoxides
9
8.5, 128.8, 131.4, 132.4, 135.3. MS (EI, m/z): 283, 265, 143, 125.
chromatography to afford the desired product 16 as a white solid
35
+
1
HRMS (MALDI): m/z calcd for C10
3
2
H
12 Cl
2
SO
3
Na (M + Na )
3
(304 mg, 48.5% yield). Mp 105-106 °C. H NMR (CDCl ): δ
04.9782, found 304.9776. IR (film): 3539, 3414, 3068, 2975,
5.70 (d, J ) 46 Hz, 1H), 7.60-7.66 (t, J ) 7.6 Hz, 2H), 7.74-
933, 1449, 1334, 1315, 1156, 1122, 1082 cm-1
.
7.82 (t, J ) 7.6 Hz, 1H), 7.95-8.03 (d, J ) 8.2 Hz, 2H). F NMR
19
(Benzenesulfonyl)monofluoromethylation of Epoxides. To the
(CDCl
3
): δ -168.2 (d, J ) 45.8 Hz, 1F). 13C NMR (CDCl
3
): δ
Et
2
O solution (5 mL) of fluoromethylphenyl sulfone (174 mg, 1.0
105.7 (d, J ) 264 Hz), 129.5, 130.2, 135.3, 135.8. MS (EI, m/z):
+
mmol) was added a hexane solution of n-butyllithium (2.0 mmol)
at -78 °C. After 30 min, BF -Et O (2.0 mmol) was added and
the solution was stirred for 5 min at the same temperature. Then,
propylene oxide (2.0 mmol in 2 mL of Et O) was slowly added.
The reaction mixture was stirred at -78 °C for an additional 2 h
and finally quenched with sodium bicarbonate solution. After usual
workup and purification as above, the desired product 10a was
obtained.
315 (M + H ), 173, 141, 125, 109, 77. HRMS (MALDI): m/z
+
3
2
calcd for C13
H11FO S
4 2
Na (M + Na ) 336.9981, found 336.9987.
-
1
IR (KBr): 3067, 3072, 2956, 1429, 1359, 1171, 1077 cm
Bis(benzenesulfonyl)monofluoromethylation of Aziridines.
n-Butyllithium in hexane (0.6 mmol) was added into the Et O (3
.
2
2
mL) solution of 17 (157 mg, 0.5 mmol) at -78 °C, and after 30
min at that temperature, aziridine 21 (0.6 mmol) was added. The
reaction mixture was stirred at temperatures ranging from -78 °C
to room temperature for another 2 h and then quenched with
saturated sodium bicarbonate solution. The desired product 22 was
obtained after the usual workup and purification.
1
-Benzenesulfonyl-1-fluoro-3-butanol (10a). 78% yield, color-
1
less oil. Two stereoisomers were obtained in a 1:1 ratio. H NMR
CDCl ): δ 1.27-1.35 (m, 6H), 1.93-2.45 (m, 6H), 4.06 (m, 0.5H),
.25 (m, 0.5H), 5.28-5.51 (dddd, J ) 48.5, 7.8, 4.5, 1.2 Hz, 0.5H),
.35-5.58 (dddd, J ) 49, 10.5, 2.3, 1.2 Hz, 0.5H), 7.56-8.02 (m,
0H). 19F NMR (CDCl
): δ -176.0 (ddd, J ) 48, 30, 17 Hz, 0.5F);
(
3
4
5
1
N-[3-(1,1-Bis(benzenesulfonyl)-1-fluoro)heptyl] p-toluene-
1
sulfonamide (22). 69% yield, white solid. H NMR (CDCl
3
): δ
3
0.72 (t, J ) 6.8 Hz, 3H), 0.91-1.13 (m, 4H), 1.21-1.53 (m, 2H),
13
3
δ -181.5 (ddd, J ) 49, 37, 13 Hz, 0.5F). C NMR (CDCl ): δ
2.40-2.83 (m, 2H), 2.43 (s, 3H), 3.64 (m, 1H), 4.68 (d, J ) 6.9
19
2
6
1
2.9/23.5 (C-4), 36.2 (d, J ) 18 Hz)/36.4 (d, J ) 23 Hz) (C-2),
Hz, 1H), 7.27-7.91 (m, 14H). F NMR (CDCl
3
): δ -147.4 (t, J
3
): δ 13.8, 21.6, 22.2, 26.9, 34.4
3.9/64.0 (C-3), 100.3 (d, J ) 270 Hz)/100.7 (d, J ) 265 Hz) (C-
) 17.2 Hz, 1F). 13C NMR (CDCl
), 129.0, 129.19, 129.26, 129.30, 134.49, 134.55, 134.94, 135.11
(d, J ) 7.1 Hz), 35.2 (d, J ) 2.1 Hz), 50.0 (d, J ) 3.4 Hz), 114.6
(d, J ) 275 Hz), 127.3, 129.1, 129.2, 129.6, 130.8 (d, J ) 1.4 Hz),
131.0, 134.2, 134.4, 135.5, 137.9, 135.5, 143.3. MS (ESI, m/z):
+
(Ar-C for all isomers). MS (EI, m/z): 233 (M + 1), 215, 143,
+
1
2
1
25. HRMS (MALDI): m/z calcd for C10
3
H13FSO Na (M + Na )
+
+
+
55.04671, found 255.04617. IR (film): 3545, 3410, 2980, 2920,
606.1 (M + K ), 590.2 (M + Na ), 568.2 (M + H ). HRMS
-
1
+
455, 1320, 1160, 1085 cm
Preparation of bis(benzenesulfonyl)monofluoromethane (17).
Under a nitrogen atmosphere, t-BuOK (224 mg, 2.0 mmol) was
added to the DMF (30 mL) solution of (PhSO CH (592 mg, 2.0
.
(MALDI): m/z calcd for C26
6 3
H30NFO S Na (M + Na ) 590.1117,
found 590.1111. IR (film): 3301, 2957, 2929, 2862, 1449, 1336,
-
1
1155, 1079 cm
.
2
)
2
2
Acknowledgment. We thank the Chinese Academy of
Sciences (Hundreds-Talent Program), the National Natural
Science Foundation of China (20502029), and the Shanghai
Rising-Star Program (06QA14063) for funding.
mmol) at 0 °C and the solution was stirred at the same temperature
for 1 h. Then, Selectfluor (2 mmol, 706 mg) dissolved in 20 mL of
DMF was added slowly at the same temperature. After removing
the ice-water bath, the reaction mixture was stirred for an additional
3
h at room temperature and then quenched with 20 mL of 10%
sulfuric acid. The mixture was then extracted with Et
O (3 × 50
mL), and the organic phase was subsequently washed with 10%
NaHCO (20 mL) and brine (25 mL). After drying over MgSO
and removal of the solvents, the residue was purified by flash
Supporting Information Available: Experimental details and
characterization data (PDF). This material is available free of charge
via the Internet at http://pubs.acs.org.
2
3
4
JO060955L
J. Org. Chem, Vol. 71, No. 18, 2006 6833