PAPER
1-(Trifluoromethyl)vinylation via Oxirane or Oxetane Ring-Opening
131
Anal. Calcd for C14H17F3O3: C, 57.93; H, 5.90. Found: C, 57.91; H,
5.95.
13C NMR: d = 39.6, 71.9, 121.3 (q, JCF = 6 Hz), 123.6 (q, JCF = 274
Hz), 125.8, 127.9, 128.5, 134.6 (q, JCF = 30 Hz), 143.2.
19F NMR: d = 93.6 (br s).
HRMS (FAB): m/z calcd for C11H11F3ONa [M + Na]+: 239.0660;
found: 239.0654.
trans-2-[1-(Trifluoromethyl)vinyl]cyclohexanol (6f)
Colorless liquid; yield: 40%.
IR (neat): 3404, 2933, 2860, 1450, 1346, 1296, 1163, 1113, 1063,
937 cm–1.
3-(Trifluoromethyl)but-3-enyl 4-Methylbenzenesulfonate (6g)
After the ring-opening reaction of ethylene oxide (5 mmol) with 1-
(trifluoromethyl)vinyllithium, solvents were partially evaporated to
ca. 25% of the original volume. Pyridine (5 mL) and TsCl (0.95 g,
5.0 mmol) were added to the residue. After the mixture was stirred
at r.t. overnight, the reaction was quenched with aq HCl (1 M; 30
mL). Organic materials were extracted with EtOAc (3 × 20 mL).
The combined extracts were washed with H2O (10 mL), brine (10
mL), and dried over MgSO4. After removal of the solvent under re-
duced pressure, the residue was purified by column chromatogra-
phy (hexane–EtOAc, 5:1) to give 6g (498 mg, 34%) as a colorless
liquid.
1H NMR: d = 1.22–1.34 (4 H, m), 1.69–1.72 (1 H, m), 1.78–1.82 (1
H, m), 1.92–1.94 (1 H, m), 2.02 (1 H, br s), 2.07–2.10 (1 H, m),
2.11–2.16 (1 H, m), 3.58 (1 H, ddd, J = 10.2, 10.2, 4.3 Hz), 5.49 (1
H, s), 5.85 (1 H, q, JHF = 1.3 Hz).
13C NMR: d = 24.7, 25.7, 33.0, 34.9, 47.1, 72.6, 118.5 (q, JCF = 6
Hz), 123.8 (q, JCF = 274 Hz), 140.8 (q, JCF = 29 Hz).
19F NMR: d = 94.0 (br s).
HRMS (FAB): m/z calcd for C9H14F3O [M + H]+: 195.0997; found:
195.0977.
IR (neat): 2970, 2929, 1599, 1358, 1171, 1117, 978, 908 cm–1.
2-Phenyl-3-(trifluoromethyl)but-3-en-1-ol (6d)
To a soln of 2-bromo-3,3,3-trifluoropropene (1.24 mL, 12 mmol)
and styrene oxide (0.91 mL, 8.0 mmol) in Et2O (40 mL) were added
dropwise BF3·OEt2 (1.52 mL, 12 mmol) and then a soln of n-BuLi
(2.71 M in hexane; 4.43 mL, 12 mmol) in Et2O (4 mL) at –100 °C.
The reaction mixture was stirred for 15 min and then allowed to
warm to r.t. The reaction was quenched with phosphate buffer (pH
7, 40 mL) and organic materials were extracted with EtOAc (3 × 30
mL). The combined extracts were washed with H2O (30 mL), brine
(30 mL), and dried over MgSO4. After removal of the solvent under
reduced pressure, the residue was purified by column chromatogra-
phy (hexane–EtOAc, 5:1) to give 6d (564 mg, 33%) as a colorless
liquid.
1H NMR: d = 2.45 (3 H, s), 2.57 (2 H, t, J = 6.6 Hz), 4.17 (2 H, t,
J = 6.6 Hz), 5.42 (1 H, q, JHF = 1.3 Hz), 5.76 (1 H, br s), 7.36 (2 H,
d, J = 8.4 Hz), 7.78 (2 H, d, J = 8.4 Hz).
13C NMR: d = 21.5, 29.1, 67.1, 121.1 (q, JCF = 6 Hz), 123.1 (q,
JCF = 274 Hz), 127.8, 129.9, 132.6, 133.0 (q, JCF = 30 Hz), 145.1.
19F NMR: d = 93.1 (br s).
Anal. Calcd for C12H13F3O3S: C, 48.97; H, 4.45. Found: C, 49.17;
H, 4.68.
1-Phenyl-6-(trifluoromethyl)hept-6-en-3-ol (7)
To a soln of 2-bromo-3,3,3-trifluoropropene (0.31 mL, 3.0 mmol)
and BF3·OEt2 (0.15 mL, 1.2 mmol) in Et2O (5 mL) was added drop-
wise a soln of n-BuLi (2.67 M in hexane; 1.1 mL, 3.0 mmol) in Et2O
(2 mL) at –100 °C. After the mixture was stirred for 15 min, a soln
of 2-phenethyloxetane (158 mg, 0.97 mmol) in Et2O (2 mL) was
added dropwise. The mixture was stirred for 15 min and warmed to
–78 °C over 2 h. After the mixture was allowed to warm to r.t., the
reaction was quenched with phosphate buffer (pH 7, 15 mL). Or-
ganic materials were extracted with EtOAc (3 × 15 mL). The com-
bined extracts were washed with H2O (15 mL), brine (15 mL), and
dried over MgSO4. After removal of the solvent under reduced pres-
sure, the residue was purified by column chromatography (hexane–
EtOAc, 5:1) to give 7 (206 mg, 82%) as a colorless liquid.
IR (neat): 3377, 3031, 2933, 2887, 1495, 1454, 1414, 1309, 1167,
1117, 1059, 949 cm–1.
1H NMR: d = 1.57 (1 H, br s), 3.78 (1 H, dd, J = 6.8, 6.8 Hz), 3.93–
4.01 (2 H, m), 5.85 (1 H, q, JHF = 1.1 Hz), 5.96 (1 H, q, JHF = 1.4
Hz), 7.26–7.30 (3 H, m), 7.34–7.37 (2 H, m).
13C NMR: d = 47.4, 65.0, 119.7 (q, JCF = 6 Hz), 123.5 (q, JCF = 275
Hz), 127.5, 128.1, 128.8, 138.2, 138.6 (q, JCF = 28 Hz).
19F NMR: d = 94.2 (br s).
HRMS (FAB): m/z calcd for C11H12F3O [M + H]+: 217.0840; found:
217.0857.
1-Phenyl-3-(trifluoromethyl)but-3-en-1-ol (6e)
IR (neat): 3354, 3028, 2927, 2862, 1496, 1454, 1323, 1165, 1113,
939 cm–1.
To a soln of 2-bromo-3,3,3-trifluoropropene (0.51 mL, 4.9 mmol)
in Et2O (15 mL) was added dropwise t-BuLi (1.47 M in pentane; 3.1
mL, 4.5 mmol) at –100 °C. After the reaction mixture was stirred
for 30 min, a soln of BF3·OEt2 (0.57 mL, 4.5 mmol) in Et2O (3 mL)
was added. After stirring for 5 min, a soln of styrene oxide (360 mg,
3.0 mmol) in Et2O (3 mL) was added. The reaction mixture was
stirred for 15 min and then allowed to warm to r.t. The reaction was
quenched with phosphate buffer (pH 7, 20 mL), and organic mate-
rials were extracted with EtOAc (3 × 20 mL). The combined ex-
tracts were washed with H2O (20 mL), brine (20 mL), and dried
over MgSO4. After removal of the solvent under reduced pressure,
the residue was purified by column chromatography (hexane–
EtOAc, 10:1) to give 6e (166 mg, 26%) as a colorless liquid.
1H NMR: d = 1.48 (1 H, br s), 1.61–1.83 (4 H, m), 2.25 (1 H, ddd,
J = 15.7, 10.5, 5.9 Hz), 2.41 (1 H, ddd, J = 15.7, 10.7, 5.0 Hz), 2.69
(1 H, ddd, J = 13.7, 9.3, 6.9 Hz), 2.80 (1 H, ddd, J = 13.7, 9.4, 6.1
Hz), 3.66 (1 H, dddd, J = 8.2, 8.2, 4.1, 4.1 Hz), 5.31 (1 H, q,
JHF = 1.4 Hz), 5.66 (1 H, q, JHF = 1.3 Hz), 7.18–7.21 (3 H, m), 7.26–
7.31 (2 H, m).
13C NMR: d = 25.7, 32.0, 35.2, 39.1, 70.5, 117.7 (q, JCF = 6 Hz),
123.8 (q, JCF = 274 Hz), 125.9, 128.4, 128.5, 138.2 (q, JCF = 29 Hz),
141.7.
19F NMR: d = 93.3 (br s).
Anal. Calcd for C14H17F3O: C, 65.10; H, 6.63. Found: C, 65.08; H,
6.86.
IR (neat): 3388, 3064, 3033, 2927, 1346, 1165, 1111, 1045, 947,
756, 698 cm–1.
1H NMR: d = 2.26 (1 H, br s), 2.55 (1 H, dd, J = 15.1, 4.9 Hz), 2.62
(1 H, ddd, J = 15.1, 8.7, 1.0 Hz), 4.84 (1 H, m), 5.38 (1 H, q,
JHF = 1.2 Hz), 5.74 (1 H, q, JHF = 1.4 Hz), 7.27–7.34 (5 H, m).
Acknowledgment
We are grateful to TOSOH F-TECH, INC. for a generous gift of 2-
bromo-3,3,3-trifluoropropene.
Synthesis 2006, No. 1, 128–132 © Thieme Stuttgart · New York