10.1002/ejoc.201701021
European Journal of Organic Chemistry
FULL PAPER
Hz, 1H), 3.78 (s, 3H); 13C NMR (126 MHz, CDCl3) δ (ppm): 167.69, 151.03,
144.90, 131.42, 115.62, 115.03, 112.48, 51.90; MS (ESI, m/z): 153
[M+H]+; HRMS (ESI): calculated (for C8H9O3+) 153.0552, found 153.0551.
Methyl (E)-3-(4-isobutylphenyl)but-2-enoate (3q). Residue was purified
by column chromatography (SiO2; Petroleum ether:EtOAc = 10:1->4:1)
yielded ester 3q (905 mg, 78%) in 82:12 E/Z ratio. 1H NMR (500 MHz,
CDCl3) δ (ppm): 7.40 (d, J = 8.2 Hz, 2H), 7.23 (d, J = 8.2 Hz, 2H), 6.14 (s,
1H), 3.74 (s, 3H), 2.57 (d, J = 1.1 Hz, 3H), 2.55 – 2.46 (m, 2H), 1.88 (dq, J
= 13.3, 6.7 Hz, 1H), 0.90 (dd, J = 6.6, 2.0 Hz, 6H); 13C NMR (126 MHz,
CDCl3) δ (ppm): 167.54, 155.94, 143.16, 139.43, 129.37, 128.41, 115.81,
51.14, 45.17, 30.27, 27.29, 22.46; MS (ESI, m/z): 233 [M+H]+; HRMS
(ESI): calculated (for C15H21O2+) 233.1542, found 233.1545. Observed
characteristic peaks for (Z)-isomer in 1H NMR spectrum: 1H NMR (500
MHz, CDCl3) δ (ppm): 5.88 (d, J = 1.3 Hz, 1H), 3.55 (s, 3H), 2.17 (d, J =
1.3 Hz, 3H).
Methyl (E)-3-(2-(allyloxy)phenyl)acrylate (3l). Residue was purified by
column chromatography (SiO2; Petroleum ether:EtOAc = 4:1->2:1->1:1)
yielded ester 3l (1.04 g, 95%) in 92:8 E/Z ratio. 1H NMR (500 MHz, CDCl3)
δ (ppm): 8.06 (d, J = 16.2 Hz, 1H), 7.54 (dd, J = 7.7, 1.7 Hz, 1H), 7.34 (ddd,
J = 8.4, 7.4, 1.7 Hz, 1H), 6.98 (td, J = 7.4, 0.6 Hz, 1H), 6.92 (dd, J = 8.3,
0.6 Hz, 1H), 6.56 (d, J = 16.2 Hz, 1H), 6.10 (ddt, J = 17.3, 10.5, 5.2 Hz,
1H), 5.45 (dq, J = 17.3, 1.6 Hz, 1H), 5.33 (dq, J = 10.6, 1.5 Hz, 1H), 4.64
(dt, J = 5.2, 1.5 Hz, 2H), 3.82 (s, 3H); 13C NMR (126 MHz, CDCl3) δ (ppm):
168.06, 157.39, 156.30, 140.39, 131.55, 131.55, 129.03, 128.98, 118.44,
112. 60, 112.49, 69.26, 51.64; MS (ESI, m/z): 219 [M+H]+; HRMS (ESI):
Methyl 2-cyclohexylideneacetate (3r). Residue was purified by column
chromatography (SiO2; Petroleum ether:EtOAc = 10:1->4:1) yielded ester
3r (578 mg, 75%). 1H NMR (500 MHz, CDCl3) δ (ppm): 1H NMR (500 MHz,
CDCl3) δ (ppm:) 5.63 (d, J = 0.8 Hz, 1H), 3.70 (s, 3H), 2.92 – 2.82 (m, 2H),
2.27 – 2.16 (m, 2H), 1.72 – 1.56 (m, 6H); 13C NMR (126 MHz, CDCl3) δ
(ppm): 13C NMR (126 MHz, CDCl3) δ (ppm): 167.46, 164.14, 112.77, 51.03,
50.93, 30.04, 28.82, 28.02, 26.44, 21.67, 21.62; MS (ESI, m/z): 155
[M+H]+; HRMS (ESI): calculated (for C9H15O2+) 155.1072, found 155.1074.
+
calculated (for C13H15O3
) 219.1021, found 219.1019. Observed
characteristic peaks for (Z)-isomer in 1H NMR spectrum: 1H NMR (500
MHz, CDCl3) δ (ppm): 7.24 (d, J = 12.4 Hz, 1H), 6.00 (d, J = 12.5 Hz, 1H),
5.30 (dq, J = 10.6, 1.5 Hz, 1H one of the =CH2), 4.58 (dt, J = 5.1, 1.6 Hz,
2H), 3.69 (s, 3H).
Methyl (E)-3-(2,6-dichlorophenyl)acrylate (3m). Residue was purified by
column chromatography (SiO2; Petroleum ether:EtOAc = 10:1->4:1->2:1)
yielded ester 3m (1.13 g, 98%) in >95:1 E/Z ratio. M.p. = 50-53 °C; 1H
NMR (500 MHz, CDCl3) δ (ppm): 7.79 (d, J = 16.4 Hz, 1H), 7.36 (d, J = 8.1
Hz, 2H), 7.19 (d, J = 8.1 Hz, 1H), 6.60 (d, J = 16.4 Hz, 1H), 3.84 (s, 3H);
13C NMR (126 MHz, CDCl3) δ (ppm): 13C NMR (126 MHz, ) δ 166.87,
138.52, 135.17, 132.14, 130.00, 128.93, 126.67, 52.23; MS (ESI, m/z): 231
and 233 [M+H]+; HRMS (ESI): calculated (for C10H9Cl2O2+) 230.9980,
found 230.9981.
Methyl 3,3-diphenylacrylate (3s). Residue was purified by column
chromatography (SiO2; Petroleum ether:EtOAc = 10:1->4:1) yielded ester
3s (740 mg, 62%). M.p. = 197-200 °C; 1H NMR (500 MHz, CDCl3) δ (ppm):
7.39 (qd, J = 3.5, 2.0 Hz, 3H), 7.38 – 7.32 (m, 2H), 7.31 – 7.28 (m, 3H),
7.23 – 7.20 (m, 2H), 6.37 (s, 1H), 3.62 (s, 3H); 13C NMR (126 MHz, CDCl3)
δ (ppm): 166.45, 157.11, 140.79, 138.80, 129.48, 129.11, 128.39, 128.33,
128.22, 127.91, 116.79, 51.29; MS (ESI, m/z): 239 [M+H]+; HRMS (ESI):
calculated (for C16H15O2+) 239.1072, found 239.1071.
Methyl (E)-3-(pyridin-2-yl)acrylate (3n). Residue was purified by column
chromatography (SiO2; Petroleum ether:EtOAc = 4:1->2:1->1:1) yielded
ester 3n (750 mg, 92%) in >95:1 E/Z ratio. M.p. = 30-32 °C; 1H NMR (500
MHz, CDCl3) δ (ppm): 8.66–8.58 (m, 1H), 7.73 – 7.64 (m, 2H), 7.42 (d, J =
General protocol for coumarin derivative (4) synthesis
A suspension of aldehyde 1 (3.6 mmol, 1.0 equiv) and stabilized Wittig
ylide 2 (4.0 mmol, 1.1 equiv) in toluene (3.6 mL, 1.0 M to 1) was placed
into a microwave vial (10 mL) equipped with a magnetic stirring bar. The
vial was sealed with a Silicone/PTFE Vial cap and placed into a CEM
Discover reactor. The resulting mixture was then irradiated (300 W) for 60
minutes (fixed time) at 220 °C (see representative reaction protocol KAH-
02-045 (for compound 4c)). The reaction mixture was allowed to cool down,
transferred to a round-bottom flask and the toluene was removed under
vacuum.
7.8 Hz, 1H), 7.30-7.23 (m, 1H), 6.94 (d, J = 15.7 Hz, 1H), 3.80 (s, 3H); 13
C
NMR (126 MHz, CDCl3) δ (ppm): 167.32, 152.89, 150.12, 143.52, 136.96,
124.44, 124.29, 121.97, 51.89; MS (ESI, m/z): 164 [M+H]+; HRMS (ESI):
calculated (for C9H10NO2+) 164.0712, found 164.0715.
Methyl (E)-3-(2,3-dihydroxyphenyl)acrylate (3o). Residue was purified
by column chromatography (SiO2; CH2Cl2:MeOH = 100:1->50:1) yielded
ester 3o (913 mg, 94%) in >95:1 E/Z ratio.
1H NMR (500 MHz, DMSO-d6) δ (ppm): 7.98 (d, J = 16.1 Hz, 1H), 7.01 (d,
J = 7.9 Hz, 1H), 6.89 (s, 1H), 6.74 (t, J = 7.9 Hz, 1H), 6.57 (d, J = 16.1 Hz,
1H), 3.80 (s, 3H); 13C NMR (126 MHz, DMSO-d6) δ (ppm): 167.73, 146.43,
146.19, 146.05, 140.90, 121.75, 119.70, 117.43, 117.21, 51.76; MS (ESI,
m/z): 195 [M+H]+; HRMS (ESI): calculated (for C10H11O4+) 195.0657, found
195.0660.
Coumarin (4a). The residue was purified by column chromatography
(SiO2, Petroleum ether:EtOAc = 4:1->2:1->1:1) yielding the desired
1
product 4a as a slightly yellow solid (468 mg, 89 %). M.p. = 69-70°C; H
NMR (500 MHz, CDCl3) δ (ppm): 7.71 (d, J = 9.5 Hz, 1H), 7.54 – 7.50 (m,
1H), 7.48 (dd, J = 7.7, 1.5 Hz, 1H), 7.31 (d, J = 8.3 Hz, 1H), 7.29 – 7.25
(m, 1H), 6.41 (d, J = 9.5 Hz, 1H); 13C NMR (126 MHz, CDCl3) δ (ppm:)
160.92, 154.14, 143.64, 131.97, 128.03, 124.58, 118.95, 116.98, 116.78;
HRMS (ESI): calculated (for C9H7O2+) 147.0446 [M+H]+, found 147.0445.
Methyl (E)-3-(4-methoxyphenyl)but-2-enoate (3p). Residue was purified
by column chromatography (SiO2; Petroleum ether:EtOAc = 10:1->4:1-
>2:1) yielded ester 3p (783 mg, 76%) in 80:20 E/Z ratio. M.p. = 50-53 °C;
1H NMR (500 MHz, CDCl3) δ (ppm): 7.45 (d, J = 8.8 Hz, 2H), 6.89 (d, J =
8.8 Hz, 2H), 6.11 (d, J = 1.0 Hz, 1H), 3.82 (s, 3H), 3.74 (s, 3H), 2.56 (d, J
= 1.0 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ (ppm): 167.59, 160.55, 155.37,
134.32, 127.71, 114.81, 113.86, 55.51, 51.21, 17.84; MS (ESI, m/z): 207
[M+H]+; HRMS (ESI): calculated (for C12H15O3+) 207.1021, found 207.1025.
Observed characteristic peaks for (Z)-isomer in 1H NMR spectrum: 1H
NMR (500 MHz, CDCl3) δ (ppm): 5.87 (d, J = 1.1 Hz, 1H), 3.81 (s, 3H),
3.57 (s, 3H), 2.16 (d, J = 1.2 Hz, 3H).
7-methoxy-2H-chromen-2-one (4b). The residue was purified by column
chromatography (SiO2, Petroleum ether:EtOAc = 4:1->2:1->1:1) yielding
the desired product 4b as a slightly yellow solid (545 mg, 86 %). M.p. =
114-115 °C; 1H NMR (500 MHz, CDCl3) δ (ppm): 7.63 (d, J = 9.5 Hz, 1H),
7.36 (d, J = 8.5 Hz, 1H), 6.86 – 6.78 (m, 2H), 6.24 (d, J = 9.5 Hz, 1H), 3.86
(s, 3H); 13C NMR (126 MHz, CDCl3) δ (ppm): 162.93, 161.34), 156.01,
143.50, 128.93, 113.27, 113.11, 112.65, 100.98, 55.80; HRMS (ESI):
calculated (for C10H9O3+) 177.0552 [M+H]+, found 177.0551.
8-hydroxy-2H-chromen-2-one (4c). The residue was purified by column
chromatography (SiO2, Petroleum ether:EtOAc = 4:1->2:1->1:1) yielding
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