Molecules 2010, 15
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2-(3,4-bis(Isobutyryloxy)phenyl)-4-oxo-4H-chromene-3,5,7-triyl tris(2-methylpropanoate) (2b): Iso-
butyric anhydride (4.75 g, 30.0 mmol, 10.0 equiv.) was added dropwise to a solution of 1 (1.00 g,
3.0 mmol, 1.0 equiv.) in pyridine (15 mL). The mixture was heated to reflux and stirred for 2 hours.
The obtained solution was diluted in CH2Cl2 (150 mL) and washed with 3 M aq. HCl (6 × 100 mL).
The organic layer was then dried over MgSO4, and filtered. The solvent was evaporated under reduced
pressure. The purification of the resulting residue by silica gel flash chromatography (eluent: 5:5:0.25
CH2Cl2/hexane/ethyl acetate) gave 2b as a pale yellow solid (1.90 g, 97% yield). 1H-NMR (250 MHz,
CD3CN, 25 °C): δ = 1.23-1.34 (m, 30H, 10 × CH3), 2.79-2.94 (m, 5H, 5 × CH), 6.94 (d, 4JH,H = 2.2 Hz,
1 H, 6-H), 7.38-7.41 (m, 2 H, 8-H, 5’-H), 7.73 (d, 4JH,H = 2.0 Hz, 1 H, 2’-H), 7.81 (dd, 3JH,H = 8.8 Hz,
4JH,H = 2.2 Hz, 1 H, 6’-H) ppm; 13C-NMR (62.9 MHz, CD3CN, 25 °C): δ = 175.9, 175.5, 175.3, 175.1,
174.8, 170.7, 157.9, 155.8, 154.5, 151.4, 145.9, 143.6, 134.8, 128.6, 127.6, 125.2, 124.7, 118.2, 115.5,
110.5, 34.9, 34.8, 34.7, 34.6, 34.5, 19.1, 19.0, 19.0, 18.9, 18.9 ppm; MS (ESI-MS): m/z 653, [M+H]+;
Elemental analysis: calcd. for C35H40O12: C 64.41, H 6.18; found C 64.45, H 6.22.
2-(3,4-bis(Isobutyryloxy)phenyl)-5-hydroxy-4-oxo-4H-chromene-3,7-diyl
bis(2-methylpropanoate)
(3b): Isobutyric anhydride (2.00 g, 12.6 mmol, 4.2 equiv.) was added dropwise to a solution of 1
(1.00 g, 3.0 mmol, 1.0 equiv.) in pyridine (15 mL). The mixture was stirred at 70 °C for 1 hour. The
obtained solution was diluted in CH2Cl2 (150 mL) and washed with 3 M aq. HCl (6 × 100 mL). The
organic layer was then dried over MgSO4, and filtered. The solvent was evaporated under reduced
pressure and the resulting residue was purified by silica gel flash chromatography (eluent: 5:5:0.25
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CH2Cl2/hexane/ethyl acetate) to afford 3b as a yellow solid (1.22 g, 70% yield). H-NMR (250 MHz,
CD3CN, 25 °C): δ = 1.24-1.30 (m, 24H, 8 × CH3), 2.79-2.92 (m, 4H, 4 × CH), 6.61 (d, 4JH,H = 2.0 Hz,
1 H, 6-H), 6.92 (d, 4JH,H = 2.2 Hz, 1 H, 8-H), 7.41 (d, 3JH,H = 8.5 Hz, 1 H, 5’-H), 7.75 (d, 4JH,H = 2.2 Hz,
1 H, 2’-H), 7.82 (dd, 3JH,H = 8.8 Hz, 4JH,H = 2.2 Hz, 1 H, 6’-H) ppm; 13C-NMR (62.9 MHz, DMF-d6, 25
°C): δ = 176.5, 174.7, 174.3, 174.1, 174.0, 161.4, 157.4, 156.4, 156.0, 145.7, 143.1, 132.3, 127.7,
127.3, 124.9, 108.6, 105.9, 102.3, 34.2, 34.0, 33.9, 18.7, 18.6, 18.5 ppm; MS (ESI-MS): m/z 583,
[M+H]+; Elemental analysis: calcd. for C31H34O11: C 63.91, H 5.88; found C 63.99, H 5.92.
2-(3,4-bis(Pivaloyloxy)phenyl)-4-oxo-4H-chromene-3,5,7-triyl tris(2,2-dimethylpropanoate) (2c):
Compound 1 (1.00 g, 3.0 mmol, 1.0 equiv.) was dissolved in pyridine (15 mL). Pivaloyl chloride
(3.62 g, 30.0 mmol, 10.0 equiv.) was then added dropwise and the mixture was heated to reflux and
stirred for 2 hours. The obtained solution was diluted in CH2Cl2 (150 mL) and washed with 3 M aq.
HCl (6 × 100 mL). The organic layer was then dried over MgSO4, and filtered. The solvent was
evaporated under reduced pressure. The purification of the resulting residue by silica gel flash
chromatography (eluent: 9:1:0.5 CH2Cl2/hexane/ethyl acetate) gave 2c as a white solid (1.88 g, 87%
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yield). H-NMR (250 MHz, DMF-d6, 25 °C): δ = 1.35-1.41 (m, 45H, 15 × CH3), 7.27 (d, JH,H = 2.2
Hz, 1 H, 6-H), 7.64 (d, 3JH,H = 8.5 Hz, 1 H, 5’-H), 7.69 (d, 4JH,H = 2.2 Hz, 1 H, 8-H), 7.92 (d, 4JH,H = 2.0
Hz, 1 H, 2’-H), 8.01 (dd, 3JH,H = 8.8 Hz, 4JH,H = 2.2 Hz, 1 H, 6’-H) ppm; 13C-NMR (62.9 MHz, DMF-
d6, 25 °C): δ = 176.3, 176.1, 175.7, 175.6, 175.3, 169.8, 157.2, 155.6, 153.8, 151.1, 145.7, 143.2,
128.0, 127.1, 127.1, 124.9, 124.2, 115.0, 114.9, 110.2, 39.3, 39.3, 39.2, 39.1, 39.0, 27.0, 26.9, 26.9,
26.8, 26.7 ppm; MS (ESI-MS): m/z 723, [M+H]+; Elemental analysis: calcd. for C40H50O12: C 66.47, H
6.97; found C 66.49, H 7.00.