S. Zheng, X. Li, H. Tan, C. Yu, J. Zhang, Z. Shen
FULL PAPER
Chromone Derivative 16: A solution of 14 (25 mg, 0.1 mmol) in
DMF (3 mL) was heated at 130 °C for 25 h. Then the mixture was
allowed to cool to room temperature and ice/water (15 mL) was
added. The mixture was extracted with ethyl acetate (2ϫ 20 mL).
The organic phase was washed with water (15 mL) and brine
of 22 (85 mg, 0.2 mmol) in acetonitrile (6 mL) in an ice/water bath.
After stirring for 1 h, water (20 mL) was added. The solution was
extracted with ethyl acetate (2ϫ 35 mL), and the organic phase
was washed with water (20 mL) and brine (20 mL). After drying
and concentrating, the residue was purified by column chromatog-
raphy (ethyl acetate/petroleum ether, 1:2) to give 23 (59 mg, 75%)
as a pale red solid, m.p. 243–245 °C. 1H NMR (400 MHz, CDCl3):
δ = 7.97 (s, 1 H), 6.73 (d, J = 10.4 Hz, 1 H), 6.61 (s, 1 H), 6.02 (s,
1 H), 5.74 (d, J = 10.0 Hz, 1 H), 3.87 (s, 3 H), 3.85 (s, 3 H), 1.47
(s, 6 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 186.3, 182.1,
173.7, 171.4, 158.80, 158.17, 155.89, 155.38, 138.0, 134.0, 131.3,
117.1, 116.1, 114.1, 112.9, 108.1, 101.1, 78.2, 63.1, 60.7, 56.6, 28.6
1
(15 mL). The dried and concentrated extract was evaluated by H
NMR spectroscopy; the residue consisted of a mixture of 15 and
16 in a 1:4 ratio. The residue was purified by preparative TLC (ethyl
acetate/petroleum ether, 1:9) to give 16 (20 mg, 80.0%) as a yellow
solid, m.p. 112–114 °C. 1H NMR (400 MHz, [D6]acetone): δ =
12.83 (s, 1 H), 8.16 (d, J = 6.0 Hz, 1 H), 6.69 (d, J = 10.0 Hz, 1
H), 6.27 (d, J = 6.0 Hz, 1 H), 6.18 (s, 1 H), 5.75 (d, J = 10.0 Hz, 1
H), 1.46 (s, 6 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 157.1,
(2 C) ppm. IR (film): ν = 3437, 3423, 1661, 1641, 1597, 1294, 1198,
˜
128.1, 114.2, 111.2, 99.8, 78.3, 27.6 ppm. IR (film): ν = 3441, 3076, 1126, 1063 cm–1. MS-ESI: m/z (%) = 395.1 (100) [M + 1]+. HRMS
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2970, 2926, 1655, 1628, 1578, 1466, 1450, 1414, 1383, 1296, 1211,
1155, 1121, 1078, 1013, 914, 837, 783, 702, 563 cm–1. ESI-MS: m/z
(%) = 245.2 (100) [M + 1]+.
(ESI+): calcd. for C22H19O7 [M + 1]+ 395.1125; found 395.1134.
Coumaronochromone Derivative 24: Methanesulfonic acid (0.6 mL)
was added to a stirred solution of 23 (40 mg, 0.1 mmol) in glacial
acetic acid (3 mL) at room temperature. The reaction proceeded at
90 °C for 4 h and was monitored by HPLC. Then the mixture was
allowed to cool to room temperature, and it was poured into cold
water (20 mL) and stirred for 15 min. The solution was extracted
with ethyl acetate (2ϫ 40 mL), and then the organic phase was
washed with saturated sodium hydrogen carbonate (25 mL) and
brine (25 mL). The dried and concentrated residue was purified by
column chromatography (ethyl acetate/petroleum ether, 1:2 to 1:1)
to afford 24 (20 mg, 50%) as an off-white solid. 1H NMR
(400 MHz, [D6]acetone): δ = 7.52 (s, 1 H), 7.34 (s, 1 H), 6.81 (s, 1
H), 6.77 (d, J = 10.0 Hz, 1 H), 5.92 (d, J = 10.4 Hz, 1 H), 5.62 (s,
1 H, -OH), 3.95 (s, 3 H), 3.93 (s, 3 H), 1.49 (s, 6 H) ppm. 13C NMR
(100 MHz, [D6]DMSO): δ = 172.5, 163.4, 157.5, 156.1, 155.8,
147.3, 145.7, 143.0, 132.4, 115.81, 115.46, 114.0, 112.4, 106.6,
101.8, 99.6, 97.6, 78.7, 56.9, 55.6, 28.6 (2 C) ppm. MS-ESI: m/z
(%) = 395.1 (100) [M + 1]+. HRMS (ESI+): calcd. for C22H19O7
[M + 1]+ 395.1125; found 395.1135.
7-(1,1-Dimethylpropargyloxy)-5-methoxychromone (17): Product 17
was prepared according to the same procedure as for the synthesis
of 29. The reaction gave a yellow solid product in 95.0% yield, m.p.
147–149 °C. 1H NMR (400 MHz, CDCl3): δ = 7.61 (d, J = 6.0 Hz,
1 H), 6.95 (s, 1 H), 6.55 (s, 1 H), 6.18 (d, J = 5.6 Hz, 1 H), 3.92 (s,
3 H), 2.70 (s, 1 H), 1.73 (s, 6 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 172.3, 156.1, 155.7, 154.7, 148.2, 109.9, 94.9, 94.12,
94.10, 80.2, 70.7, 68.1, 51.9, 25.0 ppm. IR (film): ν = 3447, 3240,
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3219, 3072, 2989, 1655, 1618, 1601, 1562, 1470, 1456, 1418, 1286,
1140, 1109, 835, 685 cm–1. HRMS (ESI+): calcd. for C15H15O4 [M
+ 1]+ 259.0965; found 259.0971.
Chromone Derivative 18: A solution of 17 (26 mg, 0.1 mmol) in
DMF (3 mL) was heated at 165 °C by microwave irradiation
(100 W) for 18 min. The solution was cooled to room temperature,
and then water (10 mL) was added. After filtration and drying,
pure 18 (25 mg, 96.2%) was obtained as a yellow solid, m.p. 230–
233 °C. 1H NMR (400 MHz, CDCl3): δ = 7.63 (d, J = 6.0 Hz, 1
H), 6.69 (d, J = 10.0 Hz, 1 H), 6.30 (s, 1 H), 6.18 (d, J = 5.6 Hz, 1
H), 5.58 (d, J = 10.0 Hz, 1 H), 3.92 (s, 3 H), 1.47 (s, 6 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 177.0, 160.9, 158.0, 154.4, 152.5,
127.7, 115.3, 114.6, 110.6, 102.8, 96.8, 78.3 56.7, 28.5 ppm. IR
Chromone Derivative 29: K2CO3 (3.79 g, 28 mmol) was added to a
solution of 15 (488 mg, 2 mmol) in dry acetone (50 mL). After stir-
ring for 10 min in an ice/water bath, Me2SO4 (1.33 mL, 14 mmol)
was added dropwise over 5 min. The mixture was heated at reflux
for 3 h under an Ar atmosphere. Then the mixture was allowed to
cool to room temperature, and water (30 mL) was added. Stirring
was continued for 20 min, and then the acetone solvent was re-
moved under reduced pressure. The mixture was extracted with
ethyl acetate (2ϫ 40 mL), and the organic phase was washed with
brine (25 mL), dried, and concentrated. The residue was purified
by chromatography (ethyl acetate/petroleum ether, 1:5–1:3) to give
product 29 (492 mg, 95.4%) as a light yellow solid, m.p. 96–98 °C.
1H NMR (400 MHz, CDCl3): δ = 7.55 (d, J = 6.0 Hz, 1 H), 6.62
(d, J = 10.0 Hz, 1 H), 6.47 (s, 1 H), 6.05 (d, J = 6.0 Hz, 1 H), 5.63
(d, J = 10.0 Hz, 1 H), 3.78 (s, 3 H), 1.35 (s, 6 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 176.3, 158.97, 158.26, 155.4, 153.27,
153.08, 131.0, 116.1, 113.98, 113.62, 113.34, 101.0, 95.7, 62.9,
(film): ν = 3447, 3092, 2966, 2927, 2856, 1647, 1593, 1572, 1481,
˜
1389, 1358, 1290, 1202, 1159, 1107, 1030, 833, 781, 704, 528,
442 cm–1. HRMS (ESI+): calcd. for C15H15O4 [M + 1]+ 259.0965;
found 259.0970.
Isoflavone Derivative 22: Methyl iodide (0.13 mL, 2.5 mmol) and
silver oxide (693 mg, 3 mmol) were added to a solution of 8
(205 mg, 0.5 mmol) in acetone (25 mL). The mixture was heated at
reflux for 3 h. After it was allowed to cool to room temperature,
the mixture was filtered and washed with acetone (10 mL). The
filtrate was concentrated, and the crude product was purified by
column chromatography (ethyl acetate/petroleum ether, 1:6) to give
product 22 (201 mg, 95%) as a pale yellow solid, m.p. 125–127 °C.
1H NMR (400 MHz, [D6]acetone): δ = 7.90 (s, 1 H), 6.93 (s, 1 H),
6.77 (s, 1 H), 6.74 (d, J = 9.6 Hz, 1 H), 6.61 (s, 1 H), 5.88 (d, J =
10.0 Hz, 1 H), 3.87 (s, 3 H), 3.85 (s, 3 H), 3.77 (s, 3 H), 3.75 (s, 3
H), 1.47 (s, 6 H) ppm. 13C NMR (100 MHz, [D6]acetone): δ =
173.8, 158.9, 157.9, 155.8, 152.7, 152.3, 150.6, 143.4, 131.2, 123.3,
117.1, 116.0, 113.34, 113.18, 113.10, 100.45, 98.98, 77.8, 62.1,
28.5 ppm. IR (film): ν = 3447, 3074, 2978, 2941, 2845, 1661, 1639,
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1603, 1558, 1466, 1433, 1400, 1354, 1283, 1252, 1157, 1119, 1097,
1067, 1024, 947, 897, 845, 831, 798, 714, 526, 484 cm–1. HRMS
(ESI+): calcd. for C15H15O4 [M + 1]+ 259.0965; found 259.0970.
Chromone Derivative 26: Piperidine (2 mL) was added to a stirred
solution of 29 (320 mg, 1.24 mmol) in MeOH (30 mL). The solu-
tion was heated at reflux for 2 h and then allowed to cool to room
temperature. The solution was concentrated to dryness to give a
yellow oil, which was dissolved in CH2Cl2 (40 mL). Pyridine
(196 mg, 2.48 mmol) and a solution of iodine (788 mg, 6.20 mmol)
in CH2Cl2 (10 mL) were added. After stirring overnight, Na2SO3
56.53, 56.24, 55.8, 27.7 (2 C) ppm. IR (film): ν = 3435, 2935, 1645,
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1606, 1514, 1215, 1203, 1031, 831 cm–1. MS-ESI: m/z (%) = 425.2
(100) [M + 1]+. HRMS (ESI+): calcd. for C24H25O7 [M + 1]+
425.1595; found 425.1601.
Isoflavone Quinone Derivative 23: A solution of cerium ammonium
nitrate (274 mg, 0.5 mmol) in water (2 mL) was added to a solution
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Eur. J. Org. Chem. 2013, 1356–1366