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T. Okano et al. / Tetrahedron 60 (2004) 4031–4035
13^2 Hz, 0.5F); EI-MS m/z (rel. %) 212 (7), 141 (10), 133
(36), 78 (70), 71 (100). Anal. Calcd for C12H13F3O3S: C;
48.98, H; 4.45. Found: C; 48.85, H; 4.58.
3.1.9. 1,2,2-Trifluoro-1-phenylsulfanylundecane (6d).
The title compound was obtained as above from 1 (95 mg,
0.50 mmol) and 1-iodononane (640 mg, 2.5 mmol) as
colorless oil: 108 mg (68%); 1H NMR d 0.88 (t,
J¼7.0 Hz, 3H), 1.13–1.42 (m, 12H), 1.54 (quint.,
J¼7.4 Hz, 2H), 1.88–2.13 (m, 2H), 5.74 (ddd, J¼52.7,
10.7, 8.0 Hz, 1H), 7.34–7.39 (m, 3H), 7.53–7.57 (m, 2H);
19F NMR d 2161.6 (dt, J¼54^2, 18^2 Hz, 1F), 2108.5
(dqd, J¼253^2, 18^2, 12^2 Hz, 1F), 2106.5 (dqd,
J¼253^2, 18^2, 9^2 Hz, 1F); EI-MS m/z (rel. %) 319
(8, Mþþ1), 318 (42, Mþ), 141 (100), 110 (17), 109 (19), 77
(11), 65 (11), 55 (16). Anal. Calcd for C17H25F3S: C; 64.12,
H; 7.91. Found: C; 63.90, H; 8.20.
3.1.5. Triethylborane-initiated radical reaction of sulfide
1 with tert-butyl iodide. To a mixture of 1 (95 mg,
0.50 mmol), tert-butyl iodide (460 mg, 2.5 mmol), and
TTMSS (250 mg, 1.00 mmol), B(C2H5)3 hexane solution
(1.0 M, 0.25 mL: 0.25 mmol) was added. Then the mixture
was exposed with air and stirred at room temperature.
B(C2H5)3 hexane solution (1.0 M, 0.25 mL: 0.25 mmol)
was added twice into the reaction mixture at 1 and 2 h later.
After 3 h stirring, the mixture was diluted with hexane and
washed with saturated aq. NaCl solution. The hexane
solution was dried over MgSO4 and the solvent was
removed under reduced pressure. The residue was
chromatographed on a SiO2 column to give 3,3,4-
trifluoro-2,2-dimethyl-4-phenylsulfanylbutane (6a) as
3.1.10. 1,2,2-Trifluoro-3-methyl-1-phenylsulfanylbutane
(6e). The title compound was obtained as above from 1
(95 mg, 0.50 mmol) and 2-iodopropane (430 mg, 2.5 mmol)
as colorless oil: 82 mg (70%); 1H NMR d 1.09 (d, J¼6.6 Hz,
3H), 1.10 (d, J¼6.9 Hz, 3H), 2.31–2.52 (m, 1H), 5.82 (ddd,
J¼52.5, 14.4, 6.9 Hz, 1H), 7.36–7.38 (m, 3H), 7.55–7.59
(m, 2H); 19F NMR d 2162.7 (dt, J¼52^2, 17^2 Hz, 1F),
2117.3 (dtd, J¼253^2, 18^2, 6^2 Hz, 1F), 2115.3 (dtd,
J¼253^2, 15^2, 8^2 Hz, 1F); EI-MS m/z (rel. %) 235 (3,
Mþþ1), 234 (24, Mþ), 141 (100), 110 (21), 109 (20), 77
(16), 65 (29), 51 (24). Anal. Calcd for C11H13F3S: C; 56.39,
H; 5.59. Found: C; 56.32, H; 5.79.
1
colorless oil: 80 mg (65%); H NMR d 1.15 (s, 9H), 5.90
(ddd, J¼52.5, 19.8, 3.0 Hz, 1H), 7.35–7.38 (m, 3H), 7.56–
7.59 (m, 2H); 19F NMR d 2108.8 (dd, J¼259^2, 21^2 Hz,
1F), 2121.1 (dt, J¼259^2, 18^2 Hz, 1F), 2156.9 (dt,
J¼52^2, 18^2 Hz, 1F); EI-MS m/z (rel. %) 248 (31, Mþ),
141 (100), 109 (13), 57 (35). Anal. Calcd for C12H15F3S: C;
58.04, H; 6.09. Found: C; 58.20, H; 6.06.
3.1.6. AIBN initiated radical reaction of sulfide 1 with
tert-butyl iodide. To a refluxing mixture of 1 (95 mg,
0.50 mmol) and tert-butyl iodide (0.32 mL, 2.5 mmol) in
benzene (2 mL) under stirring, TTMSS (50 mL, ca.
0.16 mmol) and solid AIBN (2 mg, ca. 12 mmol) was
continually added in every 3 min. The reaction was
continued for 1 h. The reaction mixture was filtered through
a short alumina column, and then the column was washed
with hexane. After evaporation of the solvent, the residue
was chromatographed on a SiO2 column eluting with
hexane to give pure 6a: 98 mg (36%).
3.1.11. 1-Cyclohexyl-1,1,2-trifluoro-2-phenylsulfany-
lethane (6f). The title compound was obtained as above
from 1 (380 mg, 2.0 mmol) and iodocyclohexane (2.10 g,
10 mmol) as colorless oil: 253 mg (46%); 1H NMR d 1.14–
1.36 (m, 5H), 1.68–1.72 (m, 1H), 1.80–1.95 (m, 4H), 2.12
(m, 1H), 5.82 (ddd, J¼52.8, 12.6, 9.3 Hz, 1H), 7.31–7.38
(m, 3H), 7.55–7.58 (m, 2H); 19F NMR d 2162.9 (dt,
J¼52^2, 18^2 Hz, 1F), 2116.1–114.0 (m, 2F); EI-MS
m/z (rel. %) 274 (39, Mþ), 141 (100), 110 (48), 77 (28), 55
(26). Anal. Calcd for C14H17F3S: C; 61.29, H; 6.25. Found:
C; 61.19, H; 5.94.
3.1.7. 1,2,2-Trifluoro-1-phenylsulfanylpentane (6b). The
title compound was obtained as above from 1 (380 mg,
2.0 mmol) and 1-iodopropane (1.36 g, 4.0 mmol) as color-
less oil: 316 mg (68%); 1H NMR d 1.00 (t, J¼7.4 Hz, 3H),
1.59 (sex, J¼7.4 Hz, 2H), 1.75–2.39 (m, 2H), 5.74 (ddd,
J¼53.0, 10.7, 8.0 Hz, 1H), 7.34–7.38 (m, 3H), 7.53–7.57
(m, 2H); 19F NMR d 2161.6 (dt, J¼52^2, 18^2 Hz, 1F),
2108.5 (dqd, J¼253^2, 18^2, 12^2 Hz, 1F), 2106.5
(dqd, J¼253^2, 15^2, 6^2 Hz, 1F); EI-MS m/z (rel. %)
234 (19, Mþ), 141 (100), 109 (22), 77 (26), 51 (27). Anal.
Calcd for C11H13F3S: C; 56.39, H; 5.59. Found: C; 56.41, H;
5.77.
3.1.12. S-Phenyl 2,2-difluoro-3,3-dimethylbutanethioate
(11a). Radical adduct 6a (90 mg, 0.36 mmol) was dissolved
in CH2Cl2 (2 mL). To the solution, MCPBA (74 mg,
0.43 mmol) was added in several portions. The resulting
mixture was stirred for 12 h at room temperature. Then, the
mixture was successively washed with 5% NaS2O3 solution
and sat. NaHCO3 solution. The CH2Cl2 solution was dried
over MgSO4, and the solvent was removed under reduced
pressure to give crude sulfoxide 10a (76 mg, 80%).
Trifluoroacetic anhydride (0.5 mL) was added to the ice-
cooled 10a under stirring, and resulting mixture was
stirred for 10 h at room temperature. Then, crashed ice
(ca. 1 g) was added to the mixture and the mixture was
stirred for 2 h. After neutralization with NaHCO3, the
mixture was extracted with Et2O. The combined extracts
were dried over Na2SO4, and the solvent was removed
under reduced pressure. The residue was chromatographed
on a silica gel column eluting with 5% EtOAc–hexane to
3.1.8. 1,2,2-Trifluoro-1-phenylsulfanyloctane (6c). The
title compound was obtained as above from 1 (95 mg,
0.50 mmol) and 1-iodohexane (530 mg, 2.5 mmol) as
1
colorless oil: 68 mg (49%); H NMR d 0.90 (t, J¼6.9 Hz,
3H), 1.31–1.44 (m, 6H), 1.496–1.598 (m, 2H), 1.95–2.18
(m, 2H), 5.74 (ddd, J¼52.8, 10.7, 8.0 Hz, 1H), 7.34–7.39
(m, 3H), 7.52–7.59 (m, 2H); 19F NMR d 2161.6 (dt,
J¼54^2, 16^2 Hz, 1F), 2108.5 (dqd, J¼253^2, 21^2,
12^2 Hz, 1F), 2106.5 (dqd, J¼253^2, 18^2, 9^2 Hz,
1F); EI-MS m/z (rel. %) 276 (33, Mþ), 141 (100), 109 (18),
77 (20), 51 (17). Anal. Calcd for C14H19F3S: C; 60.84, H;
6.93. Found: C; 60.66, H; 7.12.
1
give thioate 11a as colorless oil: 59 mg (67%); H NMR d
1.13 (s, 9H), 7.40–7.48 (m, 5H); 19F NMR d 2112.2 (s);
EI-MS m/z (rel. %) 244 (19, Mþ), 216 (11), 110 (100), 109
(50),107 (29), 87 (33), 65 (76), 59 (12), 51 (16). Anal. Calcd
for C12H14F2OS: C; 59.00, H; 5.78. Found: C; 58.89, H;
5.73.