560
Vol. 60, No. 4
CH-1′), 3.81 (3H, s, OCH3-5), 3.76 (3H, s, OCH3-3), 3.74 (3H, perature for 12h. The methanol was removed under reduced
s, OCH3-2), 1.33 (6H, d, J=6.1Hz, CH3-2′, -3′); 13C-NMR pressure to obtain the crude oils and then extracted by EtOAc.
(75MHz, CDCl3) δ: 156.0, 153.9, 151.9, 133.9, 95.1, 92.3, 71.6, The combined organic phases were washed with water and
60.7, 56.0, 55.5, 22.2; ESI-MS m/z (rel. int. %): 227 ([M+H]+, brine, and further dried over anhydrous MgSO4. The crude
100); HR-ESI-MS m/z 227.1283 [M+H]+ (Calcd for C12H19O4, was further purified by column chromatography over silica
227.1283).
gel using n-hexane–EtOAc (3:1) to obtain 14 (2.8g, 97%).
Synthesis of 1-(4-Isopropoxy-2,3,6-trimethoxyphenyl)- 14: yellow syrup; UV (MeOH) λmax: 302 (sh), 254 (sh), 238
ethanone (11) and 1-(2-Isopropoxy-3,4,6-trimethoxyphenyl)- (sh), 208nm; IR (neat) νmax: 2974, 2936, 1639, 1593, 1512,
1
ethanone (12) To a solution of 10 (50mg, 0.22mmol) in 1261, 1111cm−1; H-NMR (300MHz, CDCl3) δ: 7.30 (1H, d,
°
CH2Cl2 at 0 C, tin chloride (52μL, 0.44mmol) and acetyl J=15.8Hz, CH-2), 7.08 (1H, s, H-2″), 7.07 (1H, d, J=8.9Hz,
chloride (24μL, 0.34mmol) were added slowly. The resulting H-6″), 6.87 (1H, d, J=15.8Hz, CH-3), 6.87 (1H, d, J=8.9Hz,
mixture was stirred for 4–6h at room temperature and then H-5″), 6.35 (1H, s, H-5′), 4.61 (1H, sept, J=6.0Hz, CH-1″″),
the CH2Cl2 was removed under reduced pressure to obtain 4.60 (1H, sept, J=6.0Hz, CH-1‴), 3.87 (3H, s, OCH3-6′),
the crude oils. With the assistance of silica gel column chro- 3.86 (3H, s, OCH3-2′), 3.83 (3H, s, OCH3-3″), 3.71 (3H, s,
matography eluted by n-hexane–EtOAc (4:1), it could afford OCH3-3′), 1.41 (6H, d, J=6.0Hz, CH3-2″″, -3″″), 1.37 (6H,
the product 12 (26mg, 34%) and its regioisomeric product 11 d, J=6.0Hz, CH3-2‴, -3‴); 13C-NMR (75MHz, CDCl3) δ:
(20mg, 43%).
193.9, 153.0, 152.8, 151.7, 150.2, 149.7, 145,2, 137.3, 127.6,
11: Yellow liquid; UV (MeOH) λmax: 304 (sh), 266, 226 (sh), 126.8, 123.0, 116.9, 114.5, 110.7, 95.8, 71.6, 71.2, 61.7, 60.8,
208nm; IR (neat) νmax: 2978, 2940, 1705, 1597, 1489, 1400, 56.2, 55.9, 22.1, 21.9; ESI-MS m/z (rel. int. %): 445 ([M+H]+,
1261, 1196, 1115, 1004cm−1; 1H-NMR (300MHz, CDCl3) 100); HR-ESI-MS m/z 445.2228 [M+H]+ (Calcd for C25H33O7,
δ: 6.24 (1H, s, H-5′), 4.57 (1H, sept, J=6.2Hz, CH-1″), 3.87 445.2226).
(3H, s, OCH3-6′), 3.77 (3H, s, OCH3-3′), 3.77 (3H, s, OCH3-
Synthesis
of
1-Isopropoxy-4-(3-(4-isopropoxy-3-
2′), 2.46 (3H, s, COCH3), 1.21 (6H, d, J=6.2Hz, CH3-2″ methoxyphenyl)propyl)-2,3,5-trimethoxybenzene (15) To
-3″); 13C-NMR (75MHz, CDCl3) δ: 201.2, 153.1, 152.4, 151.3, a solution of 14 (1.9g, 4.3mmol) in trifluoroacetic acid at
137.4, 118.7, 95.6, 76.7, 61.9, 60.8, 56.0, 32.5, 22.1; ESI-MS m/z room temperature, the triethylsilane (5.5mL, 34.0mmol) was
(rel. int. %): 269 ([M+H]+, 100); HR-ESI-MS m/z 269.1390 added dropwise. The resulting reaction mixture was stirred at
[M+H]+ (Calcd for C14H21O5, 269.1389).
room temperature for 4h and then poured into water (100mL).
12: Pale yellow powder; UV (MeOH) λmax: 308 (sh), 266, It was extracted by EtOAc (100mL×3) and the combined
224 (sh), 208nm; IR (neat) νmax: 2978, 2936, 1705, 1597, 1493, organic phases were washed with water and brine, and fur-
1
1412, 1350, 1261, 1203, 1107, 1026cm−1; H-NMR (300MHz, ther dried over anhydrous MgSO4. The crude was further
CDCl3) δ: 6.25 (1H, s, H-5′), 4.56 (1H, sept, J=6.3Hz, CH- purified by column chromatography over silica gel using n-
1″), 3.87 (3H, s, OCH3-6′), 3.79 (3H, s, OCH3-4′), 3.75 (3H, s, hexane–EtOAc (5:1) to obtain 15 (1.5g, 82%). 15: colorless
OCH3-3′), 2.47 (3H, s, COCH3), 1.37 (6H, d, J=6.3Hz, CH3- liquid; UV (MeOH) λmax: 280, 232 (sh), 206nm; IR (neat) νmax
:
1
2″, -3″); 13C-NMR (75MHz, CDCl3) δ: 201.6, 154.6, 152.4, 2955, 1593, 1485, 1246, 1118, 1030cm−1; H-NMR (300MHz,
148.8, 136.2, 119.5, 92.0, 75.9, 60.7, 56.0, 55.9, 32.6, 22.4; CDCl3) δ: 6.82 (1H, d, J=8.1Hz, H-6″), 6.76 (1H, s, H-2″),
ESI-MS m/z (rel. int. %): 269 ([M+H]+, 100); HR-ESI-MS m/z 6.73 (1H, d, J=8.1Hz, H-5″), 6.27 (1H, s, H-6′), 4.51 (1H, sept,
269.1391 [M+H]+ (Calcd for C14H21O5, 269.1389).
J=5.8Hz, CH-1″″), 4.45 (1H, sept, J=5.7Hz, CH-1‴), 3.84 (3H,
Synthesis of 4-Isopropyl-3-methoxybenzaldehyde (13) s, OCH3-3″), 3.84 (3H, s, OCH3-5′), 3.81 (3H, s, OCH3-3′),
A mixture of 4 (5.0g, 32.87mmol), 2-bromopropane (6.2mL, 3.75 (3H, s, OCH3-2′), 2.62 (4H, br t, J=7.8Hz, CH2-1, CH2-3),
66.0mmol), and potassium carbonate (9.1g, 66.0mmol) in 1.80 (2H, brt, J=7.8Hz, CH2-2), 1.36 (6H, d, J=5.8Hz, CH3-
DMF (100mL) was stirred at 60 C and the reaction mixture 2″″, -3″″), 1.34 (6H, d, J = 5.7Hz, CH3-2‴, -3‴); 13C-NMR
°
was checked by TLC. After reaction completed, the mixture (75MHz, CDCl3) δ: 153.6, 152.5, 150.3, 149.6, 145.1, 140.0,
was diluted with water (300mL) and then extracted by EtOAc 136.3, 120.3, 117.5, 116.4, 112.6, 96.6, 71.8, 71.6, 61.1, 60.7,
(150mL×3). The combined organic phases were washed with 55.9, 55.8, 35.7, 31.7, 23.4, 22.3, 22.1; ESI-MS m/z (rel. int.
water and brine, and further dried over anhydrous MgSO4. %): 445 ([M+Na]+, 100); HR-ESI-MS m/z 445.2410 [M+Na]+
The crude was further purified by column chromatography (Calcd for C25H36O6Na, 445.2409).
over silica gel using n-hexane–EtOAc (7:1) to obtain 13 (6.3g,
Synthesis of Viscolin (1) To a solution of 15 (100.0mg,
°
99%). 13: colorless liquid; UV (MeOH) λmax: 310, 292, 248, 0.23mmol) in CH2Cl2 at 0 C, boron trichloride (0.12mL,
206nm; IR (neat) νmax: 2978, 2936, 2832, 2728, 1682, 1585, 1.4mmol) was added slowly and the reaction mixture was
1504, 1269, 1124cm−1; 1H-NMR (300MHz, CDCl3) δ: 9.83 stirred further for 10min at room temperature. The reac-
(1H, s, CHO), 7.42 (1H, d, J=8.0Hz, H-6), 7.40 (1H, s, H-2), tion was quenched by cold water and extracted with CH2Cl2.
6.97 (1H, d, J=8.0Hz, H-5), 4.68 (1H, sept, J=6.1Hz, CH- The CH2Cl2 extracts were combined and the organic phases
1′), 3.90 (3H, s, OCH3-3), 1.42 (6H, d, J=6.1Hz, CH3-2′, -3′); were washed with water and brine, and further dried over
13C-NMR (75MHz, CDCl3) δ: 190.8, 153.1, 150.3, 129.7, 126.6, anhydrous MgSO4. The crude was further purified by column
112.9, 109.6, 71.3, 56.0, 21.8; ESI-MS m/z (rel. int. %): 217 chromatography over silica gel using n-hexane–EtOAc (5:1)
([M+Na]+, 100); HR-ESI-MS m/z 217.0840 [M+Na]+ (Calcd to afford colorless powder 1 (71mg, 88%). 1: UV (MeOH)
for C11H14O3Na, 217.0841).
Synthesis of
λmax: 280, 228 (sh), 206nm; IR (neat) νmax: 2936, 1600, 1512,
(E)-1-(4-Isopropoxy-2,3,6-trimethoxy- 1462, 1427, 1269cm−1; 1H-NMR (300MHz, CDCl3) δ: 6.83
phenyl)-3-(4-isopropoxy-3-methoxyphenyl)prop-2-en-1-one (1H, d, J=6.7Hz, H-6″), 6.72 (1H, s, H-2″), 6.71 (1H, d,
(14) A 1N NaOH methanol solution (100mL) of 11 (1.8g, J=6.7Hz, H-5″), 6.31 (1H, s, H-6′), 5.72 (1H, s, OH-4″, D2O
6.6mmol) and 13 (2.5g, 12.9mmol) was reacted at room tem- exchangeable), 5.51 (1H, s, OH-1′, D2O exchangeable), 3.87