S. A. Shahzad, C. Venin, T. Wirth
FULL PAPER
(C), 132.3 (CH), 131.5 (C), 130.7 (CH), 130.6 (CH), 128.8 (C), 1432, 1301, 1277, 1250, 1176, 1129, 1078, 1030, 971, 767, 755, 721
128.7 (CH), 128.5 (2ϫ CH), 128.3 (CH), 127.4 (CH), 127.3 (CH), cm–1. HRMS (ESI): m/z [M + H]+ calcd. for C17H17O3: 269.1172;
126.1 (CH), 125.8 (CH), 124.2 (CH), 123.8 (CH), 52.2 (OCH3) found 269.1175.
ppm. IR (KBr): ν = 3061, 2947, 1718, 1596, 1568, 1480, 1432, 1282,
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Methyl 2-[(E)-2-Biphenylethenyl]benzoate (2g): According to GP1
compound 2g was obtained as colourless crystal in 84% yield
(12.6 mmol, 3.96 g); m.p. 138 °C. H NMR (500 MHz, CDCl3): δ
1259, 1246, 1130, 1076, 963, 795, 775 cm–1. HRMS (ES): m/z [M
+ NH4]+ calcd. for C20H20NO2: 306.1489; found 306.1491.
1
= 8.10 (d, J = 16.2 Hz, 1 H, CH=CH-Ar-Ar), 7.99 (d, J = 7.9 Hz,
1 H, Ar-H), 7.79 (d, J = 7.9 Hz, 1 H, Ar-H), 7.68–7.66 (m, 6 H,
Ar-H), 7.56 (t, J = 7.5 Hz, 1 H, Ar-H), 7.50 (t, J = 7.5 Hz, 2 H,
Ar-H), 7.41–7.36 (m, 2 H, Ar-H), 7.10 (d, J = 16.2 Hz, 1 H,
Methyl 2-[(E)-2-(2-Naphthyl)ethenyl]benzoate (2c): According to
GP1 compound 2c was obtained as colourless crystals in 87% yield
(13.06 mmol, 3.76 g); m.p. 77 °C. H NMR (400 MHz, CDCl3): δ
= 8.06 (d, J = 16.2 Hz, 1 H, CH=CH-naph), 7.89 (dd, J = 7.9,
1.3 Hz, 1 H, Ar-H), 7.82 (s, 1 H, Ar-H), 7.78–7.71 (m, 5 H, Ar-H),
7.48 (dt, J = 7.7, 1.1 Hz, 1 H, Ar-H), 7.41–7.38 (m, 2 H, Ar-H),
7.28 (t, J = 7.7 Hz, 1 H, Ar-H), 7.12 (d, J = 16.2 Hz, 1 H, CH=CH-
naph), 3.89 (s, 3 H, COOCH3) ppm. 13C NMR (125 MHz, CDCl3):
δ = 167.9, 139.3, 135.0, 133.7, 133.2, 132.2, 131.6, 130.8, 128.6,
128.4, 128.1, 127.7 (2ϫ C), 127.21, 127.05, 127.0, 126.3, 126.0,
1
CH=CH-Ar-Ar), 3.99 (s,
3
H, COOMe) ppm. 13C NMR
(125 MHz, CDCl3): δ = 167.9 (C=O), 140.7 (C), 140.6 (C), 139.3
(C), 136.6 (C), 132.2 (CH), 131.0 (CH), 130.8 (CH), 128.9 (2ϫ
CH), 128.6 (C), 127.5 (CH), 127.4 (5ϫ CH), 127.2 (CH), 127.0
(3ϫ CH), 52.2 (CH ) ppm. IR (KBr): ν = 3071, 3032, 2947, 1719,
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3
1566, 1487, 1432, 1266, 1248, 1129, 1077, 971, 832, 765, 721, 700
cm–1. HRMS (ESP): m/z [M + NH4]+ calcd. for C22H22NO2:
332.1645; found 332.1647.
123.9, 52.2 (OCH ) ppm. IR (KBr): ν = 3055, 2949, 1717, 1627,
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3
1596, 1566, 1482, 1432, 1266, 1242, 1130, 1077, 961, 814, 741 cm–1.
HRMS (ES): m/z [M + NH4]+ calcd. for C20H20NO2: 306.1489;
found 306.1493.
GP2: General Procedure for the Synthesis of Stilbene Carboxylic
Acids 3: To a mixture of 2a (2.0 g, 8.4 mmol) in 60 mL of THF/
MeOH/H2O (4:1:l) LiOH (600 mg, 25.2 mmol) was added at room
temperature. The reaction mixture was then heated at 70 °C for
12 h. After the reaction mixture was allowed to cool to room tem-
perature, reaction mixture was neutralised (pH = 6) using 1 HCl.
The product was extracted with ethyl acetate, washed with water
and brine. The extract was dried with anhydrous MgSO4, evapo-
rated under reduced pressure and then recrystallized from ethanol
to give the corresponding stilbenecarboxylic acids in very good
yields.
2-[(E)-2-Phenylethenyl]carboxylic Acid (3a):[25] According to GP2
compound 3a was obtained as colourless solid in 87% yield
(7.2 mmol, 1.64 g); m.p. 154–155 °C (ref.[22] m.p. 159–161 °C). 1H
NMR (400 MHz, CDCl3): δ = 8.04–7.98 (m, 2 H, CH=CH-Ar &
Ar-H), 7.66 (d, J = 7.8 Hz, 1 H, Ar-H), 7.49–7.47 (m, 3 H, Ar-H),
7.31–7.27 (m, 3 H, Ar-H), 7.22–7.16 (m, 1 H, Ar-H), 6.95 (d, J =
16.2 Hz, 1 H CH=CH-Ar) ppm. 13C NMR (125 MHz, CDCl3): δ
= 173.3 (C=O), 140.3 (C), 137.4 (C), 133.2 (C), 131.9 (CH), 131.7
(CH), 128.8 (3ϫ CH), 128.0 (CH), 127.6 (CH), 127.4 (CH), 127.3
Methyl 2-[(E)-2-(3-Methylphenyl)ethenyl]benzoate (2d): According
to GP1 compound 2d was obtained as light yellow viscous oil in
79% yield (11.9 mmol, 3.0 g). 1H NMR (400 MHz, CDCl3): δ =
7.90 (d, J = 16.2 Hz, 1 H, CH=CH-Ar), 7.85 (d, J = 7.9 Hz, 1 H,
Ar-H), 7.64 (d, J = 7.9 Hz, 1 H, Ar-H), 7.43 (dt, J = 7.9, 1.0 Hz, 1
H, Ar-H), 7.29–7.22 (m, 3 H, Ar-H), 7.17 (t, J = 8.6 Hz, 1 H, Ar-
H), 7.01 (d, J = 7.5 Hz, 1 H, Ar-H), 6.91 (d, J = 16.2 Hz, 1 H, Ar-
H), 3.85 (s, 3 H, COOCH3), 2.30 (s, 3 H, Ar-CH3) ppm. 13C NMR
(62.5 MHz, CDCl3): δ = 167.9 (C=O), 139.4 (C), 138.2 (C), 137.4
(C), 132.2 (CH), 131.7 (CH), 130.7 (CH), 128.7 (CH), 128.6 (C &
CH), 127.5 (CH), 127.2 (CH), 127.1 (CH), 127.0 (CH), 124.2 (CH),
52.2, 21.5 ppm. IR (KBr): ν = 3061, 3021, 2948, 1718, 1601, 1487,
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1433, 1294, 1274, 1252, 1130, 1077, 962, 779 cm–1. HRMS (AP):
m/z [M + H]+ calcd. for C17H17O2: 253.1229; found 253.1236.
Methyl 2-[(E)-2-(4-Methylphenyl)ethenyl]benzoate (2e): According
to GP1 compound 2e was obtained as colourless crystals in 82%
yield (12.3 mmol, 3.1 g) after purification; m.p. 79–80 °C. 1H NMR
(400 MHz, CDCl3): δ = 7.85 (d, J = 16.2 Hz, 1 H, CH=CH-Ar),
7.81 (d, J = 8.0 Hz, 1 H, Ar-H), 7.60 (d, J = 7.9 Hz, 1 H, Ar-H),
7.37 (t, J = 7.5 Hz, 1 H, Ar-H), 7.34 (d, J = 7.9 Hz, 2 H, Ar-H),
7.18 (t, J = 7.6, 7.6 Hz, 1 H, Ar-H), 7.05 (d, J = 7.9 Hz, 2 H, Ar-
H), 6.88 (d, J = 16.2 Hz, 1 H, 1 H, CH=CH-Ar), 3.80 (s, 3 H,
COOCH3), 2.25 (s, 3 H, ArCH3) ppm. 13C NMR (125 MHz,
CDCl3): δ = 168.0 (C=O), 139.5 (C), 137.8 (C), 134.8 (C), 132.2
(CH), 131.5 (CH), 130.7 (CH), 129.5 (2ϫ CH), 128.5 (C), 127.0
(CH), 126.9 (3ϫ CH), 126.4 (CH), 52.1 (OCH3), 21.4 (CH3) ppm.
(CH), 127.0 (2ϫ CH) ppm. IR (KBr): ν = 3330–2745, 3061, 1685,
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1601, 1565, 1495, 1447, 1406, 1301, 1275, 1253, 1078, 963, 913,
759, 744 cm–1. HRMS (ESP): m/z [M + H]+ calcd. for C15H12O2H1:
225.0910; found 225.0912. The spectroscopic data are in agreement
with literature data.[25]
2-[(E)-2-(1-Naphthyl)ethenyl]carboxylic Acid (3b): According to
GP2 compound 3b was obtained as colourless crystals in 98% yield
(8.2 mmol, 2.25 g); m.p. 160–162 °C. 1H NMR (500 MHz, CDCl3):
δ = 8.18 (d, J = 8.4 Hz, 1 H, Ar-H), 8.06 (dd, J = 7.9, 1.2 Hz, 1 H,
Ar-H), 8.01 (d, J = 16.0 Hz, 1 H, CH=CH), 7.80–7.78 (m, 2 H, Ar-
H), 7.74 (d, J = 7.4 Hz, 2 H, Ar-H), 7.70 (d, J = 16.0 Hz, 1 H,
CH=CH), 7.55 (td, J = 7.5, 1.0 Hz, 1 H, Ar-H), 7.48–7.39 (m, 3
H, Ar-H), 7.33 (td, J = 8.5, 1.1 Hz, 1 H, Ar-H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 172.6 (C=O), 140.6 (C), 134.9 (C), 133.8
(C), 133.2 (CH), 131.7 (CH), 131.4 (C), 130.7 (CH), 128.9 (CH),
128.7 (CH), 128.3 (CH), 127.8 (CH), 127.5 (CH), 127.4 (C), 126.2
(CH), 125.84 (CH), 125.80 (CH), 124.4 (CH), 123.8 (CH) ppm. IR
IR (KBr): ν = 3077, 2957, 2915, 2843, 1713, 1598, 1512, 1466, 1436,
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1271, 1249, 1192, 1128, 1080, 964, 806, 797, 749, 710 cm–1. HRMS
(ESI): m/z [M + H]+ calcd. for C17H17O2: 253.1223; found
253.1224.
Methyl 2-[(E)-2-(4-Methoxyphenyl)ethenyl]benzoate (2f): According
to GP1 compound 2f was obtained as colourless crystal in 85%
yield (12.8 mmol, 3.43 g); m.p. 80–81 °C. 1H NMR (400 MHz,
CDCl3): δ = 7.95 (d, J = 7.9 Hz, 1 H, Ar-H), 7.90 (d, J = 16.3 Hz,
1 H, CH=CH), 7.74 (d, J = 7.9 Hz, 1 H, Ar-H), 7.54–7.50 (m, 3
H, Ar-H), 7.32 (t, J = 7.5, 7.5 Hz, 1 H, Ar-H), 7.01 (d, J = 16.3 Hz,
1 H, CH=CH), 6.93 (d, J = 8.4 Hz, 2 H, Ar-H), 3.95 (s, 3 H, CO-
OCH3), 3.85 (s, 3 H, OCH3) ppm. 13C NMR (125 MHz, CDCl3):
δ = 168.0 (C=O), 159.6 (C), 139.5 (C), 132.1 (CH), 131.0 (CH),
130.7 (CH), 130.3 (C), 128.4 (C), 128.2 (2ϫ CH), 126.7 (2ϫ CH),
(KBr): ν = 3223–2513, 1675, 1598, 1564, 1482, 1402, 1403, 1266,
˜
1171, 1145, 1086, 964, 925, 794, 745, 664 cm–1. HRMS (ESI): m/z
[M + NH4]+ calcd. for C19H18NO2: 292.1332; found 292.1335.
2-[(E)-2-(2-Naphthyl)ethenyl]carboxylic Acid (3c): According to
GP2 compound 3c was obtained as colourless crystals in 95% yield
125.3 (CH), 114.2 (2ϫ CH), 55.4 (OMe), 52.1 (OMe) ppm. IR (7.9 mmol, 2.16 g); m.p. 219–220 °C (ref.[26] m.p. 211–212 °C). 1H
(KBr): ν = 3065, 3000, 2950, 2905, 2833, 1717, 1603, 1592, 1512, NMR (500 MHz, [D6]DMSO): δ = 8.30 (d, J = 16.3 Hz, 1 H,
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Eur. J. Org. Chem. 2010, 3465–3472