7762 J . Org. Chem., Vol. 62, No. 22, 1997
Nguyen and Burton
Hz, 1F); 1H NMR δ 8.2 (dm, J ) 8.9 Hz, 2H), 7.5 (dm, J ) 8.9
Hz, 2H), 5.4 (dd, J ) 25.5, 3.3 Hz, 1H); 13C NMR δ 157.3 (dd,
J ) 301.6, 292.9 Hz), 146.6 (s), 137.5 (t, J ) 7.2 Hz), 128.2
(dd, J ) 6.5, 3.4 Hz), 124.1 (s), 81.8 (dd, J ) 30.6, 13.1 Hz);
FT-IR (cm-1) 3078.6 (w), 3040.0 (w), 2945.5 (w), 2856.7 (w),
2654.2 (w), 1734.1 (s), 1602.9 (m), 1514.2 (s), 1350.2 (s), 1305.9
(w), 1255.7 (m), 1172.8 (m), 1107.2 (w), 941.3 (m), 860.3 (m);
GCMS 186 (M+ + 1, 6.1), 185 (80.5), 169 (2.2), 156 (3.3), 155
(47.7), 139 (25.8), 138 (19.5), 128 (3.0), 127 (47.1), 120 (10.8),
119 (100.0), 101 (7.8), 99 (37.6), 89 (15.9), 88 (17.9), 77 (10.9),
76 (3.3), 75 (12.4), 74 (8.6), 69 (2.5), 63 (37.4), 62 (16.9), 51
(18.4), 50 (17.9); HRMS calcd for C8H5F2NO2 185.0288, found
185.0287.
298.1, 288.7 Hz), 129.8 (m), 128.4 (m), 82.4 (dd, J ) 29.6, 13.6
Hz); FT-IR (cm-1) 3099.8 (w), 3040.0 (w), 2669.6 (w), 1865.3
(w), 1743.7 (s), 1512.3 (w), 1423.5 (w), 1357.9 (m), 1292.4 (w),
1269.2 (m), 1192.1 (s), 1093.7 (w), 949.0 (m), 868.0 (m); GCMS
203 (M+ + 1, 11.0), 202 (100.0), 201 (5.2), 182 (14.6), 163 (3.2),
152 (10.9), 151 (62.0), 133 (28.6), 125 (4.7), 114 (5.9), 101 (17.3),
99 (5.5), 88 (7.2), 75 (8.2), 63 (9.5); HRMS calcd for C10H6F4
202.0406, found 202.0419.
P r ep a r a tion of r-Br om o-â,â-d iflu or ostyr en e (12).
A
100 mL two-necked, round-bottomed flask equipped with a
septum, a Teflon-coated magnetic stir bar, and a dry ice
condenser which was connected to N2 and a mineral oil bubbler
was charged with 1.9 g (30 mmol) of acid-washed zinc, 0.3 g
(1.1 mmol) of diiodomethane, 0.12 mL (1.2 mmol) of ClSiMe3
and 10 mL of dry THF. The reaction mixture was heated to
reflux and then cooled to room temperature. The THF was
removed via syringe, and full vacuum was applied to remove
the remaining liquid. Then 20 mL of dry DMF and 2.9 g (20
mmol) of CF2dCHBr were added to the reaction flask. The
reaction mixture was heated to 60-90 °C for 30 min. 19F NMR
analysis showed two types of zinc reagents, which were
CF2dCHZnX [-63.0 (dd, J ) 56.8, 14.0 Hz), -76.1 (dd, J )
57.2, 57.2 Hz)] and CF2dCBrZnX [-69.8 (d, J ) 56.6 Hz),
-85.0 (d, J ) 56.6 Hz)]. The average ratio of these zinc
reagents was 40/60, respectively. The total yield of both zinc
reagents was 60%. The zinc reagent was syringed into a flask
which contained 5 mol % of Pd(PPh3)4 and 2 g (20 mmol) of
iodobenzene. The reaction mixture was heated at 60 °C for 4
h to give (2,2-difluoroethenyl)benzene and (1-bromo-2,2-difluo-
roethenyl)benzene in a 40/60 ratio based on 19F NMR. The
reaction mixture was introduced onto a silica gel column and
eluted with hexane to give a mixture of the two products. â,â-
Difluorostyrene was removed under full vacuum at 60 °C, and
the R-bromo-â,â-difluorostyrene, 1.8 g (48%), remained in the
flask: 19F NMR δ -78.9 (d, J ) 31.2 Hz, 1F), -85.2 (d, J )
31.2 Hz, 1F); 1H NMR δ 7.4 (m, 2H), 7.3-7.2 (m, 3H); 13C NMR
δ 153.4 (dd, J ) 294.2, 285.9 Hz), 131.8 (d, J ) 3.6 Hz), 129.0
(m), 128.6 (s), 80.2 (dd, J ) 34.3, 25.8 Hz); FT-IR (cm-1) 3084.4
(w), 3061.2 (w), 3038.1 (w), 1728.3 (s), 1435.1 (w), 1282.7 (m),
1259.6 (m), 995.3 (s), 910.5 (w); GCMS 221 (M+ + 1, 5.2), 220
(64.0), 219 (5.8), 218 (71.0), 140 (8.5), 139 (100.0), 138 (12.5),
120 (10.5), 119 (78.5), 112 (4.7), 99 (21.0), 89 (12.4), 87 (10.1),
75 (4.8), 69 (10.6), 63 (18.0); HRMS calcd for C8H5F2Br
218.9532, found 218.9738.
P r ep a r a tion of 1-(2,2-Diflu or oeth en yl)-2-flu or oben -
zen e (8). Similarly, 8 was prepared from 2.2 g (10 mmol) of
2-fluoro-1-iodobenzene, 12.5 mmol (10 mL × 1.25 M) of
CF2dCHZnX reagent in DMF, and 5 mol % of Pd(PPh3)4 at 60
°C for 2 h. Usual workup with pentane as eluent gave 1.1 g
(69%) of clear liquid 8: GLPC purity >99%; 19F NMR δ -81.8
(dd, J ) 26.2, 26.2 Hz, 1F), -82.3 (d, J ) 26.9 Hz, 1F), -117.8
1
(s, 1F); H NMR δ 7.5 (m, 1H), 7.2 (m, 1H), 7.1 (m, 1H), 7.0
(m, 1H), 5.4 (dd, J ) 25.9, 3.7 Hz, 1H); 13C NMR δ 159.9 (dd,
J ) 248.6, 3.8 Hz), 157.0 (dd, J ) 298.1, 288.7 Hz), 128.9 (d,
J ) 7.8 Hz), 124.5 (d, J ) 3.5 Hz), 118.6 (dt, J ) 12.8, 6.4 Hz),
115.7 (d, J ) 21.8 Hz), 74.9 (ddd, J ) 32.3, 13.5, 7.4 Hz); FT-
IR (cm-1) 3103.7 (w), 3047.7 (w), 2951.3 (w), 2667.7 (w), 1734.1
(s), 1574.0 (w), 1487.2 (m), 1462.1 (m), 1354.1 (m), 1246.1 (m),
1224.9 (m), 1168.9 (w), 949.0 (m); GCMS 159 (M+ + 1, 8.2),
158 (100.0), 157 (10.7), 139 (6.2), 138 (15.1), 137 (6.2), 132 (8.4),
119 (4.4), 114 (3.4), 108 (14.5), 107 (25.0), 106 (2.1), 99 (3.2),
89 (11.9), 81 (6.9), 75 (4.6), 69 (3.7), 63 (8.8), 57 (8.8); HRMS
calcd for C8H5F3 158.0343, found 158.0350.
P r ep a r a tion of 3-(2,2-Diflu or oeth en yl)ben zotr iflu o-
r id e (9). Similarly, 9 was prepared from 2.7 g (10 mmol) of
3-iodobenzotrifluoride, 12.5 mmol (10 mL × 1.25 M) of
CF2dCHZnX reagent in DMF, and 5 mol % of Pd(PPh3)4 at 60
°C for 2 h. Usual workup with hexane as eluent gave 1.3 g
(62%) of clear liquid 9: GLPC purity >99%; 19F NMR δ -63.5
(s, 3F), -81.0 (dd, J ) 26.5, 26.5 Hz, 1F), -82.7 (d, 26.5 Hz,
1F); 1H NMR δ 7.6 (s, 1H), 7.5-7.4 (m, 3H), 5.3 (dd, J ) 25.6,
3.4 Hz, 1H); 13C NMR δ 157.5 (dd, J ) 298.9, 290.5 Hz), 132.0
(t, J ) 6.7 Hz), 131.2 (m), 130.0 (q, J ) 32.3 Hz), 129.6 (s),
124.8 (m), 124.7 (q, J ) 272.2 Hz), 124.2 (m), 81.9 (dd, J )
30.5, 13.5 Hz); FT-IR (cm-1) 3068.9 (w), 3036.1 (w), 2859.5 (w),
1730.2 (m), 1438.9 (w), 1352.2 (m), 1330.9 (m), 1234.5 (m),
1180.5 (s), 1141.9 (s), 1099.5 (m), 1078.3 (m); GCMS 209 (M+
+ 1, 9.3), 208 (100.0), 207 (9.1), 189 (22.3), 187 (9.1), 169 (9.3),
158 (30.8), 145 (2.7), 139 (14.7), 138 (12.0), 119 (15.5), 107 (4.5),
99 (8.5), 94 (2.5), 89 (4.9), 88 (7.0), 75 (7.8), 69 (7.4), 63 (9.1);
HRMS calcd for C9H5F5 208.0311, found 208.0302.
P r ep a r a tion of â,â-Diflu or ostyr en e fr om Iod oben zen e
(13). Similarly, 13 was prepared from 1.02 g (5 mmol) of
iodobenzene, 7 mmol (10 mL × 0.7 M) of CF2dCHZnX reagent
in DMF, and 5 mol % of Pd(PPh3)4 at 60 °C for 4 h. Usual
workup with pentane as eluent gave 0.57 g (81%) of clear liquid
13: GLPC purity 97%; 19F NMR δ -82.9 (dd, J ) 30.8, 26.4
1
Hz, 1F), -84.8 (d, J ) 33.9 Hz, 1F); H NMR δ 7.3-7.2 (m,
P r ep a r a tion of 4-(2,2-Diflu or oeth en yl)ben zotr iflu o-
r id e (10). Similarly, 10 was prepared from 2.0 g (7.3 mmol)
of 4-iodobenzotrifluoride, 10 mmol (8 mL × 1.25 M) of
CF2dCHZnX reagent in DMF, and 5 mol % of Pd(PPh3)4 at 60
°C for 2 h. Usual workup with pentane as eluent gave 1.2 g
(80%) of clear liquid 10: GLPC purity >99%; 19F NMR δ -63.2
(s, 3F), -80.4 (dd, J ) 25.4, 25.4 Hz, 1F), -82.0 (d, J 25.3 Hz,
1F); 1H NMR δ 7.5 (d, J ) 8.3 Hz, 2H), 7.4 (d, J ) 8.3 Hz, 2H),
5.3 (dd, J ) 25.7, 3.5 Hz, 1H); 13C NMR δ 157.7 (dd, J ) 299.8,
290.4 Hz), 134.9 (t, J ) 6.6 Hz), 129.8 (qm, J ) 32.7 Hz), 128.3
(dd, J ) 6.9, 3.5 Hz), 126.1 (m), 124.8 (q, J ) 271.8 Hz), 82.0
(dd, J ) 30.2, 13.4 Hz); FT-IR (cm-1) 3047.7 (w), 2665.8 (w),
1736.0 (s), 1608.7 (w), 1411.9 (w), 1354.1 (w), 1327.1 (s), 1248.0
(m), 1174.7 (s), 1141.9 (s), 1062.8 (m), 1020.4 (w), 935.5 (m);
GCMS 209 (M+ + 1, 9.9), 208 (100.0), 207 (8.9), 189 (35.7),
187 (9.9), 169 (12.9), 158 (46.1), 139 (18.4), 138 (14.1), 119
(14.9), 107 (5.7), 99 (10,0), 88 (8.0), 87 (6.4), 79 (7.0), 75 (7.5),
63 (10.4); HRMS calcd for C9H5F5 208.0311, found 208.0316.
P r ep a r a t ion of 1,4-Bis(2,2-d iflu or oet h en yl)b en zen e
(11). Similarly, 11 was prepared from 3.3 g (10 mmol) of 1,4-
diiodobenzene, 25 mmol (20 mL × 1.25 M) of CF2dCHZnX
reagent in DMF, and 5 mol % of Pd(PPh3)4 at 60 °C for 2 h.
Usual workup with pentane as eluent gave 1.1 g (69%) of clear
liquid 11: GLPC purity >99%; 19F NMR δ -82.2 (dd, J ) 28.4,
28.4 Hz, 1F), -84.3 (d, J ) 30.3 Hz, 1F); 1H NMR δ 7.3 (s,
4H), 5.2 (dd, J ) 26.1, 3.6 Hz, 2H); 13C NMR δ 157.2 (dd, J )
5H), 5.3 (dd, J ) 26.3, 3.9 Hz, 1H); 13C NMR δ 156.6 (dd, J )
297.9, 288.4 Hz), 130.6 (t, J ) 6.1 Hz), 128.9 (s), 127.8 (dd, J
) 5.9, 3.7 Hz), 127.2 (s), 82.4 (dd, J ) 29.2, 13.5 Hz); FT-IR
(cm-1) 3088.2 (w), 3063.1 (w), 3032.3 (w), 2660.0 (w), 1716.7
(s), 1491.1 (w), 1438.9 (w), 1346.4 (m), 1238.4 (m), 1161.2 (m),
939.4 (m), 902.7 (m); GCMS 142 (M+ + 2, 0.2), 141 (5.4), 140
(100.0), 121 (3.2), 120 (8.9), 119 (9.0), 114 (13.9), 101 (4.5), 100
(1.5), 99 (4.3), 90 (56.4), 89 (12.9), 88 (5.9), 77 (1.1).
P r ep a r a tion of â,â-Diflu or ostyr en e fr om Br om oben -
zen e (14). Similarly, 14 was prepared from 0.78 g (5 mmol)
of bromobenzene, 7 mmol (10 mL × 0.7 M) of CF2dCHZnX
reagent in DMF, and 5 mol % of Pd(PPh3)4 at 60 °C for 6 h.
Usual workup with pentane as eluent gave 0.5 g (71%) of clear
liquid 14: GLPC purity >98%; 19F NMR δ -82.9 (dd, J ) 30.8,
1
26.3 Hz, 1F), -84.8 (d, J ) 33.8 Hz, 1F); H NMR δ 7.3-7.2
(m, 5H), 5.3 (dd, J ) 26.3, 3.9 Hz, 1H); 13C NMR δ 156.6 (dd,
J ) 297.9, 288.1 Hz), 130.6 (t, J ) 6.1 Hz), 128.9 (s), 127.8
(dd, J ) 5.9, 3.7 Hz), 127.2 (s), 82.4 (dd, J ) 29.3, 13.5 Hz);
FT-IR (cm-1) 3082.4 (w), 3065.1 (w), 3028.4 (w), 2660.0 (w),
1734.1 (s), 1494.9 (w), 1440.9 (w), 1350.2 (m), 1242.2 (m),
1168.9 (m), 943.2 (m), 906.6 (w); GCMS 142 (M+ + 2, 0.1), 141
(5.3), 140 (100.0), 121 (2.8), 120 (8.0), 119 (7.9), 114 (12.4), 101
(4.1), 100 (1.4), 99 (3.9), 90 (5.2), 89 (10.6), 88 (5.0), 77 (0.8).
P r ep a r a tion of (2,2-Diflu or oeth en yl)p en ta flu or oben -
zen e (15). A 50 mL, two-necked, round-bottomed flask