Preparation of Sulfonyl Fluorides and Li Sulfonates
the combined organic layers were washed with water (3 × 50 mL)
and brine (50 mL) and dried over MgSO4. Filtration and solvent
evaporation left a crude product that was purified by chromatog-
raphy on silica gel (pentane). 1b was obtained as a colorless liquid
(2.15 g, 42%). Rf ) 0.7 (pentane). 1H NMR: δ 7.65 (m, 2H), 7.12
(m, 2H); 13C NMR: δ 164.8 (d, 1JF-C ) 253.0 Hz), 138.9 (d, 3JF-C
solution was then cooled to 0 °C and quenched by dropwise addition
of water (20 mL). The aqueous phase was extracted with CH2Cl2
(3 × 20 mL), and the combined organic layers were washed with
water (3 × 10 mL) and dried over MgSO4. Filtration and solvent
evaporation left a crude product that was purified by chromatog-
raphy on silica gel (pentane) to give 5d as a colorless liquid
1
6
(0.2 g, 28%). Rf ) 0.5 (pentane). 1H NMR: δ 7.54-7.48 (m, 4H),
) 8.8 Hz), 122.9 (m), 119.5 (td, JF-C ) 338.4 Hz, JF-C ) 2.8
2
Hz), 116.9 (d, JF-C ) 22.0 Hz); 19F NMR: δ -23.32 (s, 2F),
1
0.27 (s, 9H); 13C NMR: δ 143.3, 136.3, 134.1, 127.6 (tt, JF-C
)
2
1
-108.54 (m, 1F). Anal. Calcd for C7H4BrF3S: C, 32.70; H, 1.57.
Found: C, 32.82; H, 1.68.
281.8 Hz, JF-C ) 32.5 Hz), 125.1, 123.0 (tt, JF-C ) 272.3 Hz,
2JF-C ) 45.2 Hz), -1.1, -4.0 (m); 19F NMR: δ -82.63 (t, 2F,
3JF-F ) 5.2 Hz), -122.51 (t, 2F, 3JF-F ) 5.2 Hz). Anal. Calcd for
C14H22F4SSi2: C, 47.43; H, 6.25. Found: C, 47.62; H, 6.55.
General Procedure for the Synthesis of 2a-c and 3a.
(2-Bromo-1,1,2,2-tetrafluoroethylsulfanyl)-benzene (2a).30 To a
suspension of sodium hydride (6 g, 150 mmol) in anhydrous DMF
(100 mL) was slowly added thiophenol (10.2 mL, 100 mmol) at
0 °C within 30 min. The reaction mixture was cooled to -50 °C
for 15 min before 1,2-dibromotetrafluoroethane (15 mL, 125 mmol)
was added. The resulting mixture was maintained at -50 °C for
3 h then warmed to room temperature within 1 h. The crude mixture
was cooled in an ice-water bath, and excess sodium hydride was
quenched by dropwise addition of water (150 mL). The aqueous
phase was extracted with Et2O (3 × 100 mL), the combined organic
layers were washed with water (3 × 100 mL) and brine (100 mL)
and dried over MgSO4. Filtration and solvent evaporation left a
crude product that was purified by chromatography on silica gel
(pentane). 2a was obtained as a colorless liquid (26.07 g, 90%). Rf
General Procedure for the Synthesis of 7a and 8a. Cesium
Difluorophenylsulfanylmethanesulfinate (7a). A solution of sulfur
dioxide (0.16 g, 2.5 mmol) was prepared by bubbling sulfur dioxide
into anhydrous acetonitrile (2 mL). Into that solution were added,
at -40 °C, 4a (0.12 g, 0.5 mmol) and CsF (0.09 g, 0.6 mmol).
After warming slowly to room temperature, the reaction mixture
was stirred again for 24 h (reaction monitored by TLC or 19F NMR).
After filtration of the reaction mixture and removal of volatile
materials, the resulting solid was washed with pentane to give 7a
1
as a white solid (0.18 g, >99%). Mp 127 °C. H NMR (acetone-
d6): δ 7.60 (m, 2H), 7.38-7.35 (m, 3H); 13C NMR (DMSO-d6):
δ 136.7 (t, 1JF-C ) 334.0 Hz), 135.7, 129.1, 129.0, 127.8 (t, 3JF-C
) 1.9 Hz); 19F NMR (acetone-d6): δ -85.62 (s, 2F).
1
3
) 0.8 (pentane). H NMR: δ 7.65 (d, 2H, JH-H ) 7.1 Hz), 7.50
(m, 1H), 7.41 (m, 2H); 13C NMR: δ 137.4, 131.1, 129.5, 123.6 (t,
Cesium 1,1,2,2-Tetrafluoro-2-phenylsulfanylethanesulfinate
1
(8a): White solid (91% yield); H NMR (DMSO-d6): δ 7.60 (d,
3JF-C ) 2.7 Hz), 122.8 (tt, JF-C ) 290.7 Hz, JF-C ) 33.8 Hz),
1
2
3
2H, JH-H ) 6.8 Hz), 7.51-7.44 (m, 3H); 13C NMR (DMSO-d6):
116.93 (tt, JF-C ) 312.9 Hz, JF-C ) 40.6 Hz); 19F NMR: δ
1
2
1
2
δ 136.6, 130.5, 129.4, 128.8 (tt, JF-C ) 292.8 Hz, JF-C ) 32.1
3
3
-62.61 (t, 2F, JF-F ) 8.0 Hz), -85.57 (t, 2F, JF-F ) 8.0 Hz).
General Procedure for the Synthesis of 4a,b, 5a,b, 6a.
(Difluorophenylsulfanylmethyl)-trimethylsilane (4a).29,30 1a (4.8
g, 20 mmol) was added dropwise, at -78 °C, to a mixture of Mg
turnings (0.96 g, 40 mmol), TMSCl (10.2 mL, 80 mmol), and
anhydrous THF (50 mL). The reaction mixture was stirred for 1 h
at -78 °C, then warmed to room temperature over 3 h. After the
reaction was completed (monitored by TLC or 19F NMR), most of
the THF was evaporated, and pentane was added to the residue.
The resulting salt was filtered and the filtrate concentrated to give
3
1
Hz), 124.2 (t, 2F, JF-F ) 2.2 Hz), 123.0 (tt, JF-C ) 288.7 Hz,
2JF-C ) 32.1 Hz); 19F NMR (DMSO-d6): δ -85.23 (t, 2F, JF-F
3
3
) 6.3 Hz), -127.30 (t, 2F, JF-F ) 6.3 Hz).
HRMS or combustion of new sulfinates 7a and 8a is precluded
by their thermal stability.
Synthesis of 2,2-Difluoro-1-phenyl-2-phenylmethanesulfo-
nylethanone (11). A solution of sulfur dioxide was prepared by
bubbling sulfur dioxide (1.2 g, 18 mmol) into anhydrous THF (4
mL). Into that solution were added, at -40 °C, 9 (0.9 g, 4 mmol)
and n-Bu4NF (4 mL, 1 M in THF). After warming slowly to room
temperature, the reaction mixture was stirred again for 1 h, and
volatile materials were removed. The residue was dissolved in THF
(4 mL), and benzyl bromide (2.3 mL, 19.5 mmol) was added at
-78 °C. The reaction mixture was warmed to room temperature
overnight. After volatile materials were removed, the residue was
purified by chromatography on silica gel (petroleum ether/CH2-
Cl2, 7:3) to give 11 as a white solid (0.15 g, 14%). Mp 72-74 °C.
1
4a as a yellow liquid (4.3 g, 92%). Rf ) 0.5 (pentane). H NMR:
δ 7.60 (m, 2H), 7.40-7.35 (m, 3H), 0.25 (m, 9H); 13C NMR: δ
136.3 (t, 4JF-C ) 1.1 Hz), 134.1 (t, 1JF-C ) 300.2 Hz), 129.4, 128.9,
3
3
126.4 (t, JF-C ) 4.1 Hz), -4.1 (t, JF-C ) 1.3 Hz); 19F NMR: δ
-88.01 (s, 2F).
Synthesis of [2-(4-Bromophenylsulfanyl)-1,1,2,2-tetrafluoro-
ethyl]-trimethylsilane (5c). 2c (0.37 g, 1 mmol) was added
dropwise, at -78 °C, to a mixture of Mg turnings (0.155 g, 6.4
mmol), TMSCl (1.5 mL, 11.8 mmol), and anhydrous THF (5 mL).
The reaction mixture was stirred for 8 h at -78 °C. At this
temperature, the reaction was quenched by dropwise addition of
water (20 mL). The aqueous phase was extracted with CH2Cl2 (3
× 10 mL), and the combined organic layers were washed with water
(3 × 20 mL) and dried over MgSO4. Filtration and solvent
evaporation left a crude product that was purified by chromatog-
raphy on silica gel (pentane) to give 5c as a colorless liquid (0.09
g, 25%). Rf ) 0.5 (pentane). 1H NMR: δ 7.54-7.48 (m, 4H), 0.27
1
Rf ) 0.4 (petroleum ether/CH2Cl2, 7:3). H NMR: δ 8.13 (d, 2H,
3JH-H ) 7.5 Hz), 7.69 (m), 7.53 (m, 2H), 7.52-7.43 (m, 5H), 4.59
2
(s, 2H); 13C NMR: δ 184.7 (t, JC-F ) 22.7 Hz), 135.7, 131.7 (t,
4
3JC-F ) 1.4 Hz), 131.68, 130.8 (t, JC-F ) 3.0 Hz), 129.8, 129.1,
1
129.0, 123.8, 117.0 (t, JF-C ) 302.0 Hz), 56.4; 19F NMR: δ
-103.03 (s); MS (IC): m/z ) 311 [(M + H)+], 247. Anal. Calcd
for C15H12F2O3S: C, 58.06; H, 3.90. Found: C, 58.26; H, 4.22.
General Procedure for the Synthesis of 13a-d, 14a, 15, and
16a,b. 1,1,2,2-Tetrafluoro-2-phenylsulfanylethanesulfonyl Fluo-
ride (13a). Method A. A solution of sulfur dioxide was prepared
by bubbling sulfur dioxide (4.0 g, 63 mmol) into anhydrous
acetonitrile (30 mL). 5a (5.87 g, 20.3 mmol) and CsF (3.2 g, 21
mmol) were added at -40 °C to this solution. After warming slowly
to room temperature, the reaction mixture was stirred for 24 h
(reaction monitored by TLC or 19F NMR). Then sulfuryl chloride
(2.0 mL, 25.2 mmol) was added to the reaction mixture at
-20 °C. The mixture was warmed to room temperature within 4
h, before KF (6.0 g, 105 mmol) was added. The suspension was
further stirred for 3 days more at room temperature. Volatile
materials were removed, and the residue was purified by chroma-
tography on silica gel (pentane) to give 13a as a colorless liquid
(3.76 g, 64%).
1
(s, 9H); 13C NMR: δ 138.7, 132.5, 127.0 (tt, JF-C ) 282.1 Hz,
1
2JF-C ) 32.8 Hz), 125.4, 123.8 (m), 122.7 (tt, JF-C ) 272.6 Hz,
3
2JF-C ) 45.4 Hz), -4.0 (m); 19F NMR: δ -82.81 (t, 2F, JF-F
)
5.2 Hz), -122.40 (t, 2F, 3JF-F ) 5.2 Hz). Anal. Calcd for C11H13-
BrF4SSi: C, 36.57; H, 3.63. Found: C, 36.75; H, 3.82.
Synthesis of 1-(1,1,2,2-Tetrafluoro-2-trimethylsilanylethyl-
sulfanyl]-4-trimethylsilanylbenzene (5d). 2c (0.74 g, 2 mmol) was
added dropwise, at -78 °C, to a mixture of Mg turnings (0.06 g,
2.1 mmol), TMSCl (0.6 mL, 4.8 mmol), and anhydrous THF
(5 mL). The reaction mixture was stirred for 1 day from -78 °C
to room temperature. Solution was cooled to -78 °C, Mg turnings
(0.1 g, 4.1 mmol) and TMSCl (0.6 mL, 4.8 mmol) were added,
and the reaction was stirred from -78 to +50 °C over 1 day. The
J. Org. Chem, Vol. 72, No. 24, 2007 9051