C. Lim et al. / Journal of Fluorine Chemistry 185 (2016) 206–212
211
5.11. (Z)-1-(4-fluorophenyl)-2-(2-trifluoromethylphenyl)-1,2-
difluoroethene (8)
with water (15 mL). The combined organic layers were dried over
MgSO4, and concentrated by rotary evaporation. Silica gel column
chromatography (Rf = 0.45 in hexane) gave 10 as white crystals
(0.60 g, 2.6 mmol, 68% isoiated yield, mp = 51–53 ꢀC, purity = 99% by
1H-NMR). 1H NMR (CDCl3): 7.34–7.28 (m, 7H), 6.98 (t, 3JHF = 8.5 Hz,
Palladium tetrakis(triphenylphosphine) (0.03 g, 0.026 mmol),
3 mL dry 1,4-dioxane, (Z)-1-chloro-2-(2-trifluoromethylphenyl)-
1,2-difluoroethene (0.1 g, 0.41 mmol), 4-fluorophenylboronic acid
(0.07 g, 0.50 mmol), and K3PO4 (0.26 g, 1.23 mmol) gave 8 as
colorless oil (0.06 g, 0.2 mmol, 48% isolated yield, eluent hexane).
3
2H). 19F-NMR (CDCl3): ꢂ128.0 (d, JFF = 13.8 Hz, 1F), ꢂ128.6 (d,
3JFF = 13.9 Hz, 1F), ꢂ110.8 (m, 1F). 13C NMR (CDCl3): 163.2 (d,
2
1JCF = 250.9 Hz), 145.4 (dd, 1JCF = 247.3 Hz, JCF = 21.1 Hz), 144.7 (dd,
3
3
1H NMR (CDCl3): 7.81 (d, JHH = 7.6 Hz, 1H), 7.59 (td, JHH =3JHH
=
1JCF = 246.2 Hz, 2JCF = 20.8 Hz), 130.2 (dt, 3JCF = 8.2 Hz, 3,4JCF = 3.7 Hz),
130.0 (d, 2JCF = 24.1 Hz), 129.6 (s), 128.6 (s), 128.0 (t, 3,4JCF = 4.2 Hz),
126.2 (dd, 2JCF = 24.6 Hz, 3JCF = 3.3 Hz),115.7 (d, 2JCF = 22.1 Hz). HRMS
(C14H9F3, calculated: 234.0656, observed: 234.0658). GC–MS 234
(M+, 75), 233 (28), 232 (17), 219 (17), 214 (100),183 (66), 81 (28), 75
(20), 74 (25), 63 (22), 62 (25), 57 (43), 51 (79), 50 (73).
7.6 Hz, JHH = 0.6 Hz, 1H), 7.51 (t, JHH =3JHH = 7.5 Hz, 1H), 7.37 (d,
4
3
3
4
3JHH = 7.6 Hz, 1H), 7.10 (dd, JHH = 8.9 Hz, JHF = 5.3 Hz, 2H), 6.90 (t,
3JHH,=3JHF = 8.5 Hz, 2H). 19F-NMR (CDCl3): ꢂ130.7 (d, JFF = 15.5 Hz,
3
1F), ꢂ117.6 (m, 1F), ꢂ111.1 (m, 1F), ꢂ61.3 (d, 4JFF = 10.4 Hz, 3F). 13C-
1
1
NMR (CDCl3): 162.9 (d, JCF = 249.0 Hz), 145.5 (dd, JCF = 246.5 Hz,
1
2
2JCF = 20.6 Hz), 142.6 (dd, JCF = 250.2 Hz, JCF = 22.9 Hz), 133.4 (t,
3JCF = 4JCF = 2.3 Hz), 132.4 (s), 130.9 (d, JCF = 2.6 Hz), 130.8 (qd,
5.14. Protocol 4b: Preparation of (Z)-1-(3-nitrophenyl)-2-(phenyl)-
1,2-difluoroethene (11)
4
2JCF = 25.2 Hz, JCF = 2.5 Hz), 129.1 (ddd, JCF = 8.4 Hz, JCF = 5.0 Hz,
3
3
3
4JCF = 3.4 Hz), 127.9 (dt, JCF = 23.1 Hz, JCF = 4JCF = 2.0 Hz), 127.3 (qd,
2
3
3JCF = 4 .9 Hz, JCF = 2.1 Hz), 125.5 (dd, JCF = 24.6 Hz, JCF = 3.5 Hz),
A 50 mL 3-necked round bottom, as described above, was
charged with palladium tetrakis(triphenylphosphine) (0.03 g,
4
2
3
1
2
123.4 (q, JCF = 272.3 Hz), 115.6 (d, JCF = 21.9 Hz). HRMS (C15H8F6,
calculated: 302.0530, observed: 302.0531).
0.03 mmol),
(Z)-1-chloro-2-iodo-1,2-difluoroethene
(0.22 g,
1 mmol) and 12 mL of dry dioxane. Argon was bubbled through
above Pd(0) solution by a syringe needle for 30 min. Then,
phenylboronic acid (0.13 g, 1.1 mmol) and K3PO4 (0.64 g, 3 mmol)
were added to the above solution. The temperature of the reaction
mixture was increased to the reflux (100 ꢀC) while argon was
bubbled through the reaction mixture. 19F-NMR analysis indicated
100% conversion after reflux for 2 hours. To the above reaction
mixture, (3-nitrophenyl) boronic acid (0.17 g, 1.1 mmol), palladium
tetrakis(triphenylphosphine) (0.01 g, 0.01 mmol), and K3PO4
(0.42 g, 2 mmol) were added. The temperature of the reaction
mixture was increased again to the reflux (100 ꢀC). After 19F NMR
analysis indicated 100% conversion, the reaction was stopped (6 h).
Water (10 mL) was added to the reaction mixture. Organic
materials were extracted by hexane (3 ꢁ 20 mL) and washed with
water (20 mL). The organic layer was dried over anhydrous MgSO4,
and concentrated by rotary evaporation. Silica gel column
chromatography (Rf = 0.05 in hexane) gave 11 as yellow crystals
(0.18 g, 0.69 mmol, 69% isolated yield, mp = 38–39 ꢀC, purity = 98%
by 1H NMR). 1H NMR (CDCl3): 8.19 (bt, 4,5JHF = 1.9 Hz, 1H), 8.16 (bd,
5.12. (Z)-1-(4-methoxyphenyl)-2-(3-trifluoromethylphenyl)-1,2-
difluoroethene (9)
Palladium tetrakis(triphenylphosphine) (0.03 g, 0.026 mmol),
4 mL dry 1,4-dioxane, (Z)-1-chloro-2-(4-methoxyphenyl)-1,2-
difluoroethene (0.14 g, 0.68 mmol), 3-trifluoromethylphenylbor-
onic acid (0.16 g, 0.84 mmol), and K3PO4 (0.43 g, 2.00 mmol) gave 9
as yellow oil (0.14 g, 0.45 mmol, 65% isolated yield, eluent 40:1
hexane/ethyl acetate). 1H NMR (CDCl3): 7.60 (s, 1H), 7.54 (d,
3
3
3JHH = 7.6 Hz, 1H), 7.44 (d, JHH = 7.6 Hz, 1H), 7.37 (t, JHH =3JHH = 7.9
3
4
3
Hz, 1H), 7.29 (dd, JHH = 9.0 Hz, JHH = 1.0 Hz, 2H), 6.86 (d, JHH
=
8.3 Hz, 2H). 19F-NMR (CDCl3): ꢂ121.8 (d, 3JFF = 14.2 Hz, 1F), ꢂ134.2
(d, JFF = 14.2 Hz, 1F), ꢂ63.4 (s, 3F). 13C NMR (CDCl3): 161.6 (d,
3
5JCF = 1.2 Hz), 146.6 (dd, JCF = 249.3 Hz, JCF = 20.1.Hz), 143.4 (dd,
1JCF = 242.8 Hz, 2 JCF = 22.3 Hz), 131.4 (dd, 2JCF = 24.7 Hz, 3JCF = 1.4 Hz),
131.0 (q, 2JCF = 32.5 Hz), 130.6 (m), 130.1 (t, 3JCF = 4JCF = 3.3 Hz), 128.9
1
2
3
3
4
(s), 125.6 (q, JCF = 3.7 Hz), 124.3 (dd, JCF = 8.7 Hz, JCF = 3.9 Hz),
123.7 (q, 1JCF = 270.8 Hz), 121.6 (d, 2JCF = 24.5 Hz), 114.3 (s), 55.4 (s).
HRMS (C16H11OF5, calculated: 314.0730, observed: 314.0728).
3JHH = 8.2 Hz, 1H), 7.58 (bd, 3JHH = 8.2 Hz, 1H), 7.45–7.36 (m, 6H). 19
F
NMR (CDCl3): ꢂ133.0 (d, 3JFF = 12.5 Hz, 1F), ꢂ121.3 (d, 3JFF = 12.4 Hz,
1
2
5.13. Protocol 4a: Preparation of (Z)-1-(4-fluorophenyl)-2-(phenyl)-
1,2-difluoroethene (10)
1F). 13C NMR (CDCl3): 148.3 (s), 147.1 (dd, JCF = 252.5 Hz, JCF
=
1
2
20.2 Hz), 143.3 (dd, JCF = 246.2 Hz, JCF = 22.4 Hz), 133.2 (dd,
3JCF = 4.4 Hz, JCF = 2.9 Hz), 132.0 (dd, JCF = 25.2 Hz, JCF = 1.5 Hz),
4
2
3
A 50 mL 3-necked round bottom, as described above, was
charged with acid washed zinc powder (0.39 g, 6.0 mmol) and 7 mL
of THF. Then, (Z)-1-chloro-2-iodo-1,2-difluoroethene (1.12 g,
5.0 mmol) was transferred to the above solution via syringe. The
130.6 (d, 4JCF = 1.8 Hz), 129.5 (s), 129.2 (bd, 2JCF = 23.4 Hz), 129.0 (s),
3,4
3
4
128.5 (t,
J = 3.0 Hz), 123.9 (s), 122.5 (dd, JCF = 5.1 Hz, JCF = 3.8
CF
Hz). HRMS (C14H9F2O2N, calculated: 261.0601, observed:
261.0597). GC ꢃ MS 261 (M+, 100), 215 (18), 214 (90), 194 (16),
165 (26), 164 (15), 50 (17).
reaction mixture was stirred for 1 hour at reflux temperature. 19
F
NMR confirmed the generation of the corresponding zinc reagent
(99% NMR yield). Another 50 mL 3-necked round bottom, as
described above, was charged with 1-fluoro-4-iodobenzene
(0.85 g, 3.85 mmol), and palladium tetrakis(triphenylphosphine)
(0.22 g, 0.19 mmol). The pregenerated zinc reagent was added
dropwised to the Pd(0) soiution via a syringe. The reaction mixture
was stirred for 2 h at the reflux temperature, and 19F NMR analysis
showed the formation of (Z)-1-chloro-2-(4-fluorophenyl)-1,2-
difluoroethene (98% NMR yield). Without isolation of the product,
the reaction mixture was mixed with phenylboronic acid (0.56 g,
4.6 mmol), KOH (0.85 g, 15.2 mmol), palladium tetrakis(triphenyl-
phosphine) (0.22 g, 0.19 mmol), and 15 mL of water. The reaction
mixture was stirred for 24 hours at reflux temperature, and the
completion of the reaction was confirmed by 19F NMR analysis.
After removal of volatiles by rotary evaporation, the organic
material was extracted by diethyl ether (3 ꢁ10 mL) and washed
5.15. Preparation of (1E,3Z)-1-chloro-1,2,3,4-difluoro-4-
trimethylsilylbutadiene (12)
A 50 mL 3-necked round bottom, as described above, was
charged with acid washed zinc powder (0.39 g, 6.0 mmol) and 7 mL
of THF. Then, (Z)-1-chloro-2-iodo-1,2-difluoroethene (1.12 g,
5.0 mmol) was transferred to the above solution via syringe. The
reaction mixture was stirred for 1 hour at reflux temperature, and
19F NMR analysis confirmed generation of the corresponding zinc
reagent (98% NMR yield). The stirring of the reaction mixture was
stopped to settle down unreacted zinc metal for over 1 h. The
concentration of the THF solution of the zinc reagent was
estimated to be 0.88 M by 19F NMR analysis using an internal
standard (trifluorotoluene). Another 50 mL 3-necked round
bottom, as described above, was charged with (E)-1-iodo-2-