168
M. Essers et al. / Journal of Fluorine Chemistry 121 (2003) 163–170
pressure and the crude product was purified by column
chromatography (cyclohexane/ethyl acetate 20:1) but suffe-
red from partial decomposition on silica gel. Yield: 140 mg
(m, 2F), À137.4 (d, J ¼ 53:4 Hz, 2F), À162.1 (m, 1F);
þ þ
GC/MS: m/z (%) 286 [M ], 266 [M À HF], 251, 223,
159, 151, 141, 127, 109, 107, 95, 91. Anal. calcd. for
C H F O : C, 50.35; H, 5.28. Found C, 49.93; H, 5.18.
1
(35%). H NMR: d 0.89 (t, J ¼ 7:2 Hz, 3H), 1.22–1.41
(m, 6H), 1.63 (s, 3H), 1.68 (s, 3H), 1.52–2.60 (m, 6H), 2.67
(
m, 2H); 13C NMR: d 13.9, 18.7, 18.7, 22.4, 22.6, 27.1 (dt,
1
2 15 5 2
4.4. Diels–Alder reaction of o-quinodimethane (5)
with 2-fluorooct-1-en-3-one (2a)
J ¼ 5:1 Hz), 28.8 (dt, J ¼ 20:3 Hz), 31.4, 36.8, 38.0
(
2
dt, J ¼ 25:4 Hz), 99.4 (d, J ¼ 180:6 Hz), 120.8, 124.8,
19
12.2 (d, J ¼ 30:5 Hz); F NMR: d À164.7 (m); GC/
4.4.1. 1-(2-Fluoro-1,2,3,4-tetrahydronaphthalen-2-yl)-
hexan-1-one (6)
Zinc dust (500 mg, 7.6 mmol) was stirred with saturated
þ
þ
MS: m/z (%) 226 [M ], 206 [M À HF], 191, 150, 135,
1
27, 107, 99, 43.
aqueous NH Cl. Then the zinc was washed with water,
4
4.3.2. 1-(1-Fluoro-3,4-dimethylcyclohex-3-enyl)-
octan-1-one (3b)
ethanol, diethyl ether, and dimethyl formamide (DMF).
The zinc activated in this way was placed into a 10 ml
round-bottomed flask, which was cooled by water circula-
tion through an external jacket. 2-Fluorooct-1-en-3-one (2a)
(144 mg, 1.0 mmol) was dissolved in this flask in DMF
(2 ml) and 0.3 ml of a solution of 1,2-bisbromomethylben-
zene (4) (530 mg, 2.0 mmol) in DMF (1.5 ml) were added.
Being water-cooled, the solution was sonicated with an
ultrasonic-finger for 15 min. Subsequently, the solution of
4 (0.3 ml) was added and sonicated in the same fashion. This
procedure was repeated until 4 was consumed completely.
Then the solution was sonicated for another 30 min, diethyl
ether (10 ml) was added and the solid was removed using a
centrifuge. The solution was washed with water (3 Â 10 ml),
In accordance with the procedure described above for 3a,
-fluorodec-1-en-3-one (2b) (180 mg, 1.0 mmol) was reac-
2
ted to afford 3b. Owing to the susceptibility for decomposi-
tion, the crude 3b was just separated from polymers by
column filtration (silica gel, cyclohexane/ethyl acetate
2
6
3
1
2
0:1). Yield: 170 mg (66%). 1H NMR: d 0.89 (t, J ¼
:6 Hz, 3H), 1.18–1.40 (m, 10H), 1.62 (s, 3H), 1.66 (s,
H), 1.49–2.60 (m, 6H), 2.68 (m, 2H); 13C NMR: d 14.0,
8.7, 18.7, 22.5, 23.0, 27.1, 28.8 (dt, J ¼ 22:9 Hz), 29.0,
9.1, 31.7, 36.8, 38.0 (dt, J ¼ 22:8 Hz), 99.4 (d,
1
9
J ¼ 180:6 Hz), 120.8, 124.8, 212.2 (d, J ¼ 28:0 Hz);
F
þ
NMR: d À164.7 (m); GC/MS: m/z (%) 254 [M ], 234
þ
[
M À HF], 219, 155, 150, 135, 127, 107, 57.
dried over MgSO and the solvent was evaporated. The
4
crude product was separated from polymers by column
filtration (silica gel, cyclohexane/ethyl acetate 20:1).
Unreacted 2-fluorooct-1-en-3-one (2a) was removed in
oil-pump vacuum at room temperature. Further purification
was not possible as 6 decomposes on silica gel. Yield:
120 mg (48%). 1H NMR: d 0.91 (t, J ¼ 6:9 Hz, 3H),
1.18–1.71 (m, 6H), 1.85–2.10 (m, 2H), 2.74 (dt, J ¼ 7:2,
3.3 Hz, 2H), 2.77–3.09 (m, 3H), 3.27 (dd, J ¼ 39:6, 17.6 Hz,
4.3.3. 1-(1-Fluoro-3,4-dimethylcyclohex-3-enyl)-
decan-1-one (3c)
In accordance with the procedure described above for
b, 2-fluorododec-1-en-3-one (2c) (209 mg, 1.0 mmol) was
3
reacted to afford 3c (190 mg, 65%). 1H NMR: d 0.88
(
1
1
t, J ¼ 6:6 Hz, 3H), 1.13–1.36 (m, 14H), 1.62 (s, 3H),
.66 (s, 3H), 1.48–2.60 (m, 6H), 2.67 (ddt, J ¼ 7:4, 3.3,
13
13
.4 Hz, 2H); C NMR: d 14.1, 18.7, 18.7, 22.6, 23.0, 27.2
1H), 6.95–7.18 (m, 4H); C NMR: d 13.9, 22.4, 22.6, 24.6
(
2
dt, J ¼ 5:1 Hz), 28.6, 28.8 (dt, J ¼ 22:9 Hz), 29.2, 29.4,
(dt, J ¼ 5:1 Hz), 29.2 (dt, J ¼ 22:9 Hz), 31.4, 35.8 (dt,
9.5, 31.8, 36.9, 38.0 (dt, J ¼ 25:4 Hz), 99.4 (d,
J ¼ 22:9 Hz), 36.8, 99.1 (d, J ¼ 185:7 Hz), 126.2, 126.3,
1
9
19
J ¼ 183:1 Hz), 120.8, 124.9, 212.3 (d, J ¼ 27:9 Hz);
F
128.5, 129.1, 134.7, 139.4, 211.7 (d, J ¼ 30:5 Hz);
F
þ
þ
NMR: d À164.8 (m); GC/MS: m/z (%) 282 [M ], 262
NMR: d À164.9 (m); GC/MS: m/z (%) 228 [M À HF],
þ
[
M À HF], 247, 155, 150, 135, 127, 107, 85, 71, 57, 55, 43.
172, 157, 129, 99, 71, 43.
4
4
.3.4. 2,2,3,3-Tetrafluoropropyl 1-fluoro-3,
-dimethylcyclohex-3-ene carboxylate (3d)
4.5. Lewis acid mediated Diels–Alder reactions of
cyclopentadiene (7) with the dienophiles 2 and 10
According to the procedure described above for 3a,
,2,3,3-tetrafluoropropyl 2-fluoroacrylate (2d) (204 mg,
.0 mmol) was reacted to afford 3d. The crude product
2
1
4.5.1. Preparation of titanium BINOLate C
To a suspension of powdered molecular sieves 4 A
˚
was purified by column chromatography (cyclohexane/ethyl
1
(250 mg) in dry toluene (3 ml) under an argon atmosphere,
0.88 ml (0.25 mmol) of a 0.28 molar solution of di(isopro-
poxy)titanium dichloride in dry toluene and (R)-(þ)-
binaphthol (71.5 mg, 0.25 mmol) were added under stirring
at RT. Isopropanol was removed azeotropically from the
brown-red suspension without heating under reduced pres-
sure until the solvent was reduced to ca. half of its volume.
The mediator suspension thus obtained was used directly in
the corresponding Diels–Alder reactions.
acetate 9:1). Yield: 210 mg (68%). H NMR: d 1.64 (s, 3H),
1
.66 (s, 3H), 1.90–2.80 (m, 6H), 4.58 (tt, J ¼ 12:6 Hz,
J ¼ 1:4 Hz, 2H), 5.52 (tt, J ¼ 53:2 Hz, J ¼ 3:8 Hz, 1H);
1
3
C NMR: d 18.3, 18.3, 26.9 (dt, J ¼ 5:4 Hz), 29.1 (dt,
J ¼ 22:2 Hz), 38.1 (dt, J ¼ 23:6 Hz), 60.3 (tt, J ¼ 30:5 Hz),
9
3
1
3.2 (d, J ¼ 184:5 Hz), 111.1 (tt, J ¼ 251:5 Hz, J ¼
7:5 Hz), 114.0 (tt, J ¼ 249:7 Hz, J ¼ 27:8 Hz), 125.1,
19
28.9, 170.5 (d, J ¼ 26:4 Hz); F NMR: d À123.5