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benzenesulfinate (1.64 g, 10 mmol), dissolved in CH2Cl2
(5 mL). Then, a 1 M solution of bromine in CH2Cl2 was
dropped under stirring within 45 min. After stirring for 6.5 h at
room temperature, the reaction mixture was filtered, the filtrate
was washed with water (20 mL) and the organic phase was
dried over MgSO4 then evaporated in vacuo. The crude residue
was purified by column chromatography over silica gel (eluent:
petroleum ether/diethyl ether 4:1) and 1.92 g (7 mmol, 70%) of
7 was isolated as a colorless oil. 1H NMR (200 MHz): d 8.0–7.6
(m, 5H), 4.1 (q, J = 7.1, 2H), 3.2 (t, J = 6.9, 2H), 2.7 (t, J = 6.9,
2H), 1.2 (t, J = 7.1, 3H). 13C NMR (50 MHz): d 170.9, 144.5,
133.9, 129.4, 126.9, 61.0, 34.0, 30.7, 14.0. MS: m/z 229 (4%,
Mꢁ+–OEt), 157, 141, 133 (100%, Mꢁ+–PhSO2), 77, 51, 45, 29.
Chromatography of the crude residue over silica gel offered
pure 9a as an oil in a 60% yield.
4.5. Oxidation of ethyl 3-(trifluoromethylthio)propionate
2a into (trifluoromethanesulfonyl)propionate 1a
A 30% (w/w) aqueous solution of H2O2 (0.26 mL,
2.55 mmol) was dropped at room temperature onto a solution
of 2a (0.13 g, 0.64 mmol) in acetic acid (0.5 mL). The mixture
was brought to 80–90 8C for 2 h then poured into water (5 mL)
and extracted with diethyl ether (3 ꢂ 20 mL). The gathered
organic phases were washed with 1N aqueous NaOH until pH 8,
then with water until neutral, dried over MgSO4 and
concentrated under vacuo at room temperature. A colorless
oil was recovered (0.12 g, 80%). 1H NMR (200 MHz): d 4.2 (q,
J = 7.1, 2H), 3.6 (t, J = 7.5, 2H), 2.9 (t, J = 7.5, 2H), 1.3 (t,
J = 7.1, 3H). 13C NMR (50 MHz): d 169.1, 119.5 (q, J = 327),
62.0, 45.4, 26.3, 14.1. 19F NMR (188 MHz): d ꢀ78.5 (s). MS:
m/z 235 (1%, Mꢁ++1), 189, 165, 101, 73, 69, 55 (100%), 45, 29.
4.2. Reaction of ethyl 3-(phenylsulfonylthio)propionate 7
with sodium trifluoroacetate
A solution of 7 (0.27 g, 1 mmol) in DMAc (8 mL) was added
to CuI (0.39 g, 2 mmol) and sodium trifluoroacetate (0.56 g,
4.1 mmol). The resulting mixture was stirred at 160 8C for 4 h,
then filtered. The filtrate was washed with water (10 mL) then
extracted with diethyl ether (3 ꢂ 20 mL). The gathered organic
phases were dried over MgSO4 then evaporated under vacuo at
room temperature. 19F NMR analysis of the crude residue, with
PhOCF3 as internal standard, indicated the formation of 2a in a
4.6. Formation of sodium triflinate 3a from
(trifluoromethanesulfonyl)propionate 1a
A solution of 1a (0.21 g, 0.9 mmol) in methanol (6 mL) was
treated at room temperature with sodium methoxide (0.05 g,
0.9 mmol). GC monitoring of the reaction indicated that it was
complete after 5–10 min. Then, methanol was evaporated under
vacuum at 40 8C and the pasty residue was dried in a dessicator
over P2O5 and under vacuum. Sodium triflinate 3a was obtained
as a white solid (0.14 g) in a quantitative yield. 13C NMR
(50 MHz): d 125.5 (q, J = 346). 19F NMR (188 MHz): d ꢀ87.9
(s).
1
32% crude yield. 19F NMR and H NMR data for 2a were
identical with those already reported [2,11].
4.3. Reaction of ethyl 3-(phenylsulfonylthio)propionate 7
with sodium trichloroacetate
A solution of 7 (0.27 g, 1 mmol) in diglyme (2 mL) was
added to sodium trichloroacetate (0.37 g, 2 mmol). The
resulting mixture was stirred at 80–85 8C for 1 h, then filtered.
The precipitate was washed with ether and this extract joined
to the diglyme solution. The resulting mixture was extracted
with water (10 ꢂ 10 mL) then dried over MgSO4 and
evaporated under vacuo at room temperature. GC analysis
of the crude residue, with an internal standard, indicated the
formation of 9a in a 75% crude yield. 1H NMR (200 MHz): d
4.2 (q, J = 7.1, 2H), 3.4 (t, J = 7.0, 2H), 2.8 (t, J = 7.0, 2H), 1.3
(t, J = 7.1, 3H). 13C NMR (50 MHz): d 171.1, 97.9, 61.1, 33.0,
31.8, 14.2. MS: m/z 215 (6%, Mꢁ+–Cl), 133, 117, 87, 73, 45,
29 (100%, Et).
4.7. Oxidation of benzyl trifluoromethyl sulfide 11 into
benzyl trifluoromethyl sulfone 10
A 30% (w/w) aqueous solution of H2O2 (12.7 mL,
124.3 mmol) was dropped at room temperature onto a solution
of 11 (59.6 g, 31.06 mmol) in acetic acid (23 mL). The mixture
was brought to 90 8C for 2 h then poured into water (5 mL) and
extracted with diethyl ether (3 ꢂ 100 mL). The gathered
organic phases were washed with water (3 ꢂ 75 mL), saturated
aqueous NaHCO3 (2 ꢂ 75 mL) and water again (2 ꢂ 75 mL),
then dried over MgSO4 and concentrated under vacuum at room
temperature. The resulting solid was recrystalyzed in CCl4 (25–
1
4.4. Reaction of ethyl 3-(thiocyanato)propionate 5 with
sodium trichloroacetate
30 mL) to offer a white and pure product (4.60 g, 66%). H
NMR (200 MHz): d 7.43 (m, 5H), 4.47 (s, 2H). 19F NMR
(188 MHz): d ꢀ76.91 (s).
A solution of 5 (1 mmol) in diglyme (2 mL) was added to
sodium trichloroacetate (5 mmol). The resulting mixture was
stirred at 80–85 8C for 1 h, then filtered. The precipitate was
washed with ether and this extract joined to the diglyme
solution. Diethyl ether and a solution of K2CO3 were added to
the resulting mixture which was then extracted with water
(10 ꢂ 10 mL) then dried over MgSO4 and evaporated under
vacuo at room temperature. The aqueous solution was treated
with aqueous sodium hypochlorite to oxidize cyanide ions.
4.8. Synthesis of 14 from benzyl trifluoromethyl sulfone 10
K2CO3 (485 mg, 3.5 mmol) then benzyl bromide
(0.365 mL, 3 mmol) were added to a solution of benzyl
triflone 10 (673 mg, 3 mmol) in dry acetonitrile (12 mL). The
mixture was brought to reflux (82 8C) for 20 h, then filtered,
diluted with water and extracted with diethyl ether
(2 ꢂ 25 mL). The gathered organic phases were washed with