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R. Zhang et al. / Tetrahedron 67 (2011) 3010e3016
a white solid (0.095 g, 62%). Mp 112e114 ꢁC. 1H NMR (300 MHz,
CDCl3)
7.49 (dd, J¼0.8, 3.5 Hz, 1H, ArH), 7.45 (d, J¼5.3 Hz, 1H, H4),
1.03 mmol), dichlorobis(triphenylphosphine) palladium(II)
(0.030 g, 0.043 mmol), tetrabutylammonium iodide (0.016 g,
0.043mmol), caesiumfluoride(0.39g, 2.58mmol)andtolueneewater
(1:1, 20 mL). After chromatography, the desired furanone was
obtained as a yellow solid (0.158 g, 85%). Mp 189e192 ꢁC. 1H NMR
d
7.38 (dd, J¼0.7, 5.1 Hz,1H, ArH), 7.08e7.05 (m,1H, ArH), 6.30 (s,1H, ]
CH), 6.17 (d, J¼5.3 Hz, 1H, H3). 13C NMR (75.6 MHz, CDCl3)
d 169.5,
146.6, 143.7, 135.9, 131.3, 130.8, 127.7, 118.0, 107.5. UV (CH3OH) lmax
203 nm (
3
11,782 Mꢀ1cmꢀ1), 234 (8396), 362 (22,138). IR (KBr)
(300 MHz, CDCl3)
ArH), 7.55 (d, J¼5.4 Hz, 2H, H4), 6.35 (d, J¼5.4 Hz, 1H, H3), 6.08 (s, 1H,
]CH). 13C NMR (75.6 MHz, CDCl3)
169.0, 150.5, 147.2, 144.9, 138.9,
131.0, 123.9, 120.1, 111.0. UV (CH3OH) lmax 201 nm
11,809 Mꢀ1cmꢀ1), 223 (10,988), 326 (27,401). IR (KBr) ymax1793,
d
8.25 (d, J¼9.2 Hz, 2H, ArH), 7.93 (d, J¼8.9 Hz, 1H,
ymax1737, 1645, 1544, 1415, 1370, 1335, 1244, 1108, 1070, 936, 886,
795, 733, 688 cmꢀ1. HRMS (ESI) m/z found 179.0157; C9H7O2S
(MþH)þ requires 179.0167 (100%).
d
(3
4.1.4. 5-(Thiophen-3-ylmethylene)furan-2(5H)-one 7d. This com-
pound was prepared by the same method as compound 7a, from
furanone 2 (0.15 g, 0.86 mmol), thiophen-3-ylboronic acid 6d
(0.13 g, 1.03 mmol), dichlorobis(triphenylphosphine) palladium(II)
(0.030 g, 0.043 mmol), tetrabutylammonium iodide (0.016 g,
0.043 mmol), caesium fluoride (0.39 g, 2.58 mmol) and tolue-
neewater (1:1, 20 mL). After chromatography, the desired fur-
anone was obtained as a white solid (0.105 g, 69%). Mp 61e63 ꢁC.
1560, 1554, 1513, 1344, 1102, 1063, 935, 876, 823, 804, 749, 690 cmꢀ1
.
HRMS (ESI) m/z found 216.0318; C11H6NO4 (MꢀHþ)ꢀ requires
216.0302 (100%).
4.1.8. 5-(4-(Trifluoromethoxy)benzylidene)furan-2(5H)-one 7h. This
compound was prepared by the same method as compound 7a,
from furanone 2 (0.15 g, 0.86 mmol), 4-(trifluoromethoxy)phenyl-
boronic acid 6h (0.21 g, 1.03 mmol), dichlorobis(triphenylphos-
phine) palladium(II) (0.030 g, 0.043 mmol), tetrabutylammonium
iodide (0.016 g, 0.043 mmol), caesium fluoride (0.39 g, 2.58 mmol)
and tolueneewater (1:1, 20 mL). After chromatography, the desired
furanone was obtained as a yellow solid (0.145 g, 66%). Mp
1H NMR (300 MHz, CDCl3)
d 7.72e7.73 (m, 1H, ArH), 7.51 (dd,
J¼1.2, 5.1 Hz, 1H, ArH), 7.45 (d, J¼5.3 Hz, 1H, H4), 7.32 (dd, J¼2.9,
5.1 Hz, 1H, ArH), 6.17 (d, J¼5.3 Hz, 1H, H3), 6.10 (s, 1H, ]CH). 13C
NMR (75.6 MHz, CDCl3)
126.2, 117.9, 108.9. UV (CH3OH) lmax 204 nm (
d 170.0, 147.4, 144.6, 134.2, 128.8, 128.6,
3
17,286 Mꢀ1cmꢀ1),
62e64 ꢁC. 1H NMR (300 MHz, CDCl3)
d
7.78 (d, J¼8.8 Hz, 2H, ArH),
237 (8279), 337 (29,097). IR (KBr) ymax1747, 1604, 1550, 1509,
1446, 1366, 1257, 1175, 1110, 1075, 1025, 931, 892, 812, 769,
680 cmꢀ1. HRMS (ESI) m/z found 179.0160; C9H7O2S (MþH)þ re-
quires 179.0167 (100%).
7.48 (d, J¼5.5 Hz, 1H, H4), 7.20 (d, J¼8.8 Hz, 2H, ArH), 6.22 (d,
J¼5.5 Hz, 1H, H3), 5.99 (s, 1H, ]CH). 13C NMR (75.6 MHz, CDCl3)
d
169.7, 149.4, 148.6, 145.0, 132.0, 131.3, 121.8, 120.9, 118.5, 112.3. UV
(CH3OH) lmax 201 nm (3
14,141 Mꢀ1cmꢀ1), 224 (13,629), 326
(34,021). IR (KBr) ymax1749, 1605, 1549, 1509, 1277, 1222, 1166, 1117,
1071, 934, 885, 822, 769 cmꢀ1. HRMS (ESI) m/z found 255.0276;
C12H6F3O3 (MꢀHþ)ꢀ requires 255.0275 (100%).
4.1.5. 5-(4-(Trifluoromethyl)benzylidene)furan-2(5H)-one 7e. This
compound was prepared by the same method as compound 7a,
from furanone 2 (0.15 g, 0.86 mmol), 4-(trifluoromethyl)phenyl-
boronic acid 6e (0.20 g, 1.03 mmol), dichlorobis(triphenylphos-
phine) palladium(II) (0.030 g, 0.043 mmol), tetrabutylammonium
iodide (0.016 g, 0.043 mmol), caesium fluoride (0.39 g, 2.58 mmol)
and tolueneewater (1:1, 20 mL). After chromatography, the desired
furanone was obtained as a white solid (0.159 g, 77%). Mp 59e61 ꢁC.
4.1.9. 4-Bromo-5-(2,4-difluorobenzylidene)furan-2(5H)-one 8a and
5-(2,4-difluorobenzylidene)-4-(2,4-difluorophenyl)furan-2(5H)-one
9c. A mixture of furanone 3 (0.20 g, 0.79 mmol), 2,4-difluor-
ophenylboronic acid 6j (0.25 g, 1.58 mmol), dichlorobis(triphenyl-
phosphine)
palladium(II)
(0.055
g,
0.079
mmol),
1H NMR (300 MHz, CDCl3)
J¼8.2 Hz, 1H, ArH), 7.50 (d, J¼5.4 Hz, 2H, H4), 6.27 (d, J¼5.4 Hz, 1H,
H3), 6.03 (s, 1H, ]CH). 13C NMR (75.6 MHz, CDCl3)
169.5, 149.6,
145.0, 136.0, 130.7, 130.2 (t), 125.6, 122.0, 119.3, 112.1. UV (CH3OH)
lmax 201 nm (
11,809 Mꢀ1cmꢀ1), 223 (10,988), 326 (27,401). IR
(KBr) ymax1749, 1653, 1605, 1549, 1508, 1344, 1285, 1224, 1166, 1071,
d
7.86 (d, J¼8.2 Hz, 2H, ArH), 7.62 (d,
tetrabutylammonium iodide (0.030 g, 0.079 mmol) and caesium
fluoride (0.72 g, 4.74 mmol) in tolueneewater (1:1, 20 mL) was
heated to reflux under argon for 36 h. Brine (40 mL) was added and
the mixture was extracted with ethyl acetate (3ꢂ50 mL). The
combined organic layers were dried over sodium sulfate. The sol-
vent was removed under reduced pressure to give the crude
product. The crude product was purified using gravity column
chromatography with dichloromethane/light petroleum (1/2) to
afford the furanone 8a as a white solid (0.054 g, 24%) and the fur-
anone 9c as white solid (0.068 g, 27%).
d
3
934, 884, 894, 821 cmꢀ1
. HRMS (ESI) m/z found 241.0465;
C12H7F3O2 (MþH)þ requires 241.0476 (100%).
4.1.6. 5-(3-(Trifluoromethyl)benzylidene)furan-2(5H)-one 7f. This
compound was prepared by the same method as compound 7a,
from furanone 2 (0.15 g, 0.86 mmol), 3-(trifluoromethyl)phenyl-
boronic acid 6f (0.20 g, 1.03 mmol), dichlorobis(triphenylphos-
phine) palladium(II) (0.030 g, 0.043 mmol), tetrabutylammonium
iodide (0.016 g, 0.043 mmol), caesium fluoride (0.39 g, 2.58 mmol)
and tolueneewater (1:1, 20 mL). After chromatography, the desired
furanone was obtained as a white solid (0.154 g, 75%). Mp 65e67 ꢁC.
4.1.10. 4-Bromo-5-(2,4-difluorobenzylidene)furan-2(5H)-one
8a. Mp 110e112 ꢁC. 1H NMR (300 MHz, CDCl3)
d
8.19e8.11 (m, 1H,
ArH), 6.93e6.87 (m, 1H, ArH), 6.81e6.77 (m, 1H, ArH), 6.52 (s, 1H, ]
CH), 6.38 (s, 1H, H3). 13C NMR (75.6 MHz, CDCl3)
165.8, 150.1 (d),
146.2, 137.6, 134.8, 133.1 (d), 121.4, 119.7, 112.7 (d), 103.9, 102.4. UV
(CH3OH) lmax 200 nm (
59,821 Mꢀ1cmꢀ1), 252 (18,003). IR (KBr)
d
3
1H NMR (300 MHz, CDCl3)
d
8.00 (d, J¼6.8 Hz, 1H, ArH), 7.90 (s, 1H,
ymax 1779, 1613, 1558, 1550, 1550, 1434, 1273, 1146, 1107, 1088, 967,
910, 833, 800, 611, 580 cmꢀ1. HRMS (ESI) m/z found 308.9344;
C11H5BrF2NaO2 (MþNa)þ requires 308.9339 (100%).
ArH), 7.53e7.50 (m, 2H, ArH), 7.48 (d, J¼5.3 Hz, 1H, H4), 6.25 (d,
J¼5.3 Hz, 1H, H3), 6.01 (s, 1H, ]CH). 13C NMR (75.6 MHz, CDCl3)
d
169.5, 149.3, 145.0, 133.4, 131.4, 130.9, 129.3, 127.0, 125.5 (t), 121.9,
119.1, 112.1. UV (CH3OH) lmax 202 nm (3
18,374 Mꢀ1cmꢀ1), 223
4.1.11. 5-(2,4-Difluorobenzylidene)-4-(2,4-difluorophenyl)furan-2
(5H)-one 9c. Mp 144e146 ꢁC. 1H NMR (300 MHz, CDCl3)
(14,811), 322 (41,871). IR (KBr) ymax1758, 1650, 1551, 1326, 1300,
1221, 1189, 1164, 1134, 1108, 1097, 1079, 942, 899, 860, 812, 798,
690 cmꢀ1. HRMS (ESI) m/z found 239.0326; C12H6F3O2 (MꢀHþ)ꢀ
requires 239.0325 (100%).
d
7.42e7.28 (m, 2H, ArH), 7.03e6.88 (m, 4H, ArH), 6.18 (s, 1H, ]CH),
6.06 (s, 1H, H3). 13C NMR (75.6 MHz, CDCl3)
d
168.5, 163.1, 162.5,
159.8 (d), 158.7 (d), 151.1, 148.6, 133.8 (d), 132.0 (d), 118.0, 112.9 (d),
112.6 (d), 105.8, 105.5, 104.6, 104.3, 103.9. UV (CH3CN) lmax 231 nm
4.1.7. 5-(4-Nitrobenzylidene)furan-2(5H)-one 7g. This compound
was prepared by the same method as compound 7a, from furanone
2 (0.15 g, 0.86 mmol), 4-nitrophenylboronic acid 6g (0.17 g,
(3
2796 Mꢀ1cmꢀ1), 297 (5592). IR (KBr) ymax 3105, 1775, 1621, 1481,
1455, 1346, 1235, 1208, 1116, 1100, 964, 927, 873, 750 cmꢀ1. HRMS