Molecules 2016, 21, 1058
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6.73–6.69 (m, 2H), 6.31 (s, 1H), 4.26 (dd, 1H, J = 11.4 and 4.2 Hz), 4.10 (dd, 1H, J = 11.4 and 7.2 Hz), 3.91
(s, 3H), 3.91 (s, 3H), 3.87 (s, 3H), 3.16 (dd, 1H, J = 13.8 and 4.2 Hz), 2.73 (m, 1H), 2.65–2.61 (m, 1H);
13C-NMR (150 MHz, CDCl3)
δ 191.6, 159.8, 155.5, 153.5, 146.5, 144.2, 135.2, 130.2, 121.9, 114.3, 111.4,
108.7, 98.8, 68.8, 61.5, 61.4, 55.9, 48.6, 32.6; HRMS (EI): mass calculated for C19H20O7 [M+], 360.1209;
found, 360.1208.
3-(3,4-Dihydroxybenzyl)-7-hydroxy-5,6-dimethoxychroman-4-one (15c). A solution of the 3-benzylidene-4-
chromanone (18c) (20 mg, 33 µmol) and 10% Pd/C (3.5 mg) in MeOH was placed under an atmosphere
of hydrogen. After stirring for 1 h, the reaction mixture was diluted with ethyl acetate, filtered through
a Celite pad and concentrated under reduced pressure. The residue was purified by flash column
chromatography on silica gel (ethyl acetate:n-hexane = 1:1) to afford the 3-benzyl-4-chromanone (15c
)
(11 mg, 99%). 1H-NMR (600 MHz, CDCl3)
δ
6.79 (d, 1H, J = 8.4 Hz), 6.77 (d, 1H, J = 2.4 Hz), 6.63
(dd, 1H, J = 8.4 and 1.8 Hz), 6.30 (s, 1H), 4.26 (dd, 1H, J = 11.4 and 4.2 Hz), 4.09 (dd, 1H, J = 8.4 and
4.2 Hz), 3.90 (s, 3H), 3.89 (s, 3H), 3.08 (dd, 1H, J = 13.8 and 4.2 Hz), 2.70–2.67 (m, 1H), 2.62 (dd, 1H,
J = 13.8 and 10.8 Hz); 13C-NMR (150 MHz, CDCl3)
δ 192.2, 159.9, 155.9, 153.5, 143.8, 142.5, 135.2, 131.0,
121.6, 116.0, 115.3, 108.5, 98.9, 68.8, 61.5, 61.4, 48.5, 32.4; HRMS (EI): mass calculated for C18H18O7 [M+],
346.1053; found, 346.1056.
7-Hydroxy-3-(4-hydroxybenzyl)-5,6-dimethoxychroman-4-one (6). A solution of the 3-benzylidene-4-
chromanone (18d) (23 mg, 0.05 mmol) and 10% Pd/C (5 mg) in MeOH was placed under an atmosphere
of hydrogen. After stirring for 1 h, the reaction mixture was diluted with ethyl acetate, filtered through
a Celite pad and concentrated under reduced pressure. The residue was purified by flash column
chromatography on silica gel (ethyl acetate:n-hexane = 1:1) to afford the 3-benzyl-4-chromanone (
6
)
1
(14 mg, 94%). H-NMR (600 MHz, CDCl3)
δ
7.09 (d, 2H, J = 8.4 Hz), 6.78 (d, 2H, J = 8.4 Hz), 6.30 (s, 1H),
4.62 (dd, 1H, J = 11.4 and 4.2 Hz), 4.08 (dd, 1H, J = 11.4 and 7.2 Hz), 3.91 (s, 3H), 3.90 (s, 3H), 3.15
(dd, 1H, J = 13.8 and 4.2 Hz), 2.73–2.69 (m, 1H), 2.66 (dd, 1H, J = 13.8 and 10.2 Hz); 13C-NMR (150 MHz,
CDCl3)
δ 191.7, 159.8, 155.6, 154.3, 153.5, 135.2, 130.3, 130.3, 115.4, 108.6, 98.8, 68.8, 61.5, 61.4, 48.5, 32.0;
HRMS (EI): mass calculated for C18H18O6 [M+], 330.1103; found, 330.1102.
7-Hydroxy-5,6-dimethoxy-3-(4-methoxybenzyl)chroman-4-one ( ). A solution of the 3-benzylidene-4-
7
chromanone (18e) (23 mg, 0.05 mmol) and 10% Pd/C (5 mg) in MeOH was placed under an atmosphere
of hydrogen. After stirring for 1 h, the reaction mixture was diluted with ethyl acetate, filtered through
a Celite pad and concentrated under reduced pressure. The residue was purified by flash column
chromatography on silica gel (ethyl acetate:n-hexane = 1:2) to afford the 3-benzyl-4-chromanone (
7
)
1
(13 mg, 80%). H-NMR (600 MHz, CD3COCD3)
δ
7.07–7.05 (m, 2H), 6.76–6.73 (m, 2H), 6.09 (dd, 1H,
J = 4.8 and 3.0 Hz), 4.14 (d, 1H, J = 4.2 Hz), 3.94 (d, 1H, J = 8.4 Hz), 3.71 (s, 3H), 3.71–3.62 (m, 6H),
3.00–3.98 (m, 1H), 2.62–2.61 (m, 1H), 2.53–2.49 (m, 1H); 13C-NMR (150 MHz, CDCl3)
190.0, 159.6,
δ
158.5, 157.1, 154.7, 136.3, 160.8, 130.8, 130.1, 113.9, 108.5, 99.1, 69.1, 60.8, 60.6, 54.6, 48.3, 31.5; HRMS
(EI): mass calculated for C19H20O6 [M+], 344.1260; found, 344.1257.
7-Hydroxy-3-(3-hydroxy-4-methoxybenzyl)-5,6-dimethoxychroman-4-one (2). To a solution of the
7-hydroxy-5,6-dimethoxy-4-c◦hromanone (15b) (10 mg, 0.03 mmol) in CH2Cl2 (5 mL) was added
TMSI (5 µL, 0.09 mmol) at 0 C for 1 h. The mixture was concentrated in vacuo. The residue was
purified by flash column chromatography on silica gel (ethyl acetate:n-hexane = 1:2) to afford the
1
5,7-dihydroxy-6-methoxy-4-chromanone (
2
) (7.1 mg, 71%). H-NMR (600 MHz, CD3OD)
δ
6.81 (d, 1H,
J = 1.8 Hz), 6.73 (d, 1H, J = 7.8 Hz), 6.67 (dd, 1H, J = 8.4 and 1.8 Hz), 5.90 (s, 1H), 4.25 (dd, 1H, J = 11.4
and 4.2 Hz), 4.09 (dd, 1H, J = 11.4 and 7.2 Hz), 3.83 (s, 3H), 3.77 (s, 3H), 3.12 (dd, 1H, J = 13.8 and
4.8 Hz), 2.86–2.81 (m, 1H), 2.68 (d, 1H, J = 10.2 Hz); 13C-NMR (150 MHz, CD3OD)
δ 199.3, 160.1, 159.3,
156.0, 148.2, 145.5, 130.0, 129.6, 121.9, 115.4, 112.8, 102.1, 95.0, 69.5, 60.1, 55.5, 47.3, 32.7; HRMS (EI):
mass calculated for C18H18O7 [M+], 346.1053; found, 346.1054.
3-(3,4-Dihydroxybenzyl)-5,7-dihydroxy-6-methoxychroman-4-one
(3
). To
a
solution of the
7-hydroxy-5,6-dimethoxy-4-chromanone (15c) (20 mg, 0.03 mmol) in CH2Cl2 (5 mL) was added