Wu et al.
JOCNote
124.6, 112.5, 101.3, 101.0, 93.4, 92.9, 56.1, 55.6, 55.4, 38.0, 21.5;
ESIMS (m/z) 367 [M þ H]þ, 389 [M þ Na]þ; HRMS (MALDI)
calcd for C17H19O7S [M þ H]þ 367.0846, found 367.0845.
4-C-(2,3,4,6-Tetra-O-benzyl-β-D-glucopyranosyl)-7- mesyloxy-
1,3,6-trimethoxyxanthene (8) and 2-C- (2,3,4,6-Tetra-O-benzyl-
β-D-glucopyranosyl)-7-mesyloxy- 1,3,6-trimethoxyxanthene (9).
To a solution of 6 (510 mg, 1.39 mmol) and 7 (1.50 g, 2.10 mmol)
in dry CH2Cl2 (5 mL) was added TMSOTf (25 μL, 0.14 mmol)
127.81, 127.76, 127.6, 127.5, 120.9, 116.0, 107.3, 106.8, 100.9,
91.1, 81.9, 79.3, 78.6, 74.2, 74.1, 73.7, 73.5, 73.0, 70.2, 68.2, 56.4,
56.3, 56.0, 38.5; ESIMS (m/z) 903 [M þ H]þ, 925 [M þ Na]þ;
HRMS (MALDI) calcd for C51H51O13S [M þ H]þ 903.3045,
found 903.3061.
4-C-(2,3,4,6-Tetra-O-benzyl-β-D-glucopyranosyl)-7-hydroxy-
1,3,6-trimethoxyxanthone (12). To a solution of 10 (40 mg, 0.044
mmol) in 1,4-dioxane (35 mL) was added 2 N aq NaOH (7.5
mL). The solution was heated to 60 °C and stirred for 24 h. After
the solution was cooled to room temperature, the 1,4-dioxane
was removed in vacuo, and the resulting mixture was neutralized
with 1 N HCl and extracted with CH2Cl2. The organic layer was
washed with brine, dried over anhydrous Na2SO4, and concen-
trated under reduced pressure. The residue was purified by silica
gel column chromatography (petroleum ether/CH2Cl2/EtOAc =
˚
dropwise in the presence of freshly activated 4 A molecular
sieves at 0 °C. The mixture was allowed to warm to room
temperature and stirred for 1 h. The mixture was then filtered
through Celite. The filtrate was concentrated in vacuo. The
residue was purified by silica gel column chromatography
(petroleum ether/CH2Cl2/EtOAc = 6:2:1) to afford 8 (745
mg, 60%) and 9 (173 mg, 14%) as white solids. 8: mp 61-62
°C; [R]28D þ30.7 (c 0.93, CHCl3); 1H NMR (400 MHz, CDCl3) δ
7.39-6.99 (m, 21 H), 6.75 (s, 1 H), 6.23 (s, 1 H), 6.08 (d, J = 8.0
Hz, 1 H), 4.94 (d, J = 11.2 Hz, 1 H), 4.82 (d, J = 11.2 Hz, 2 H),
4.63-4.34 (m, 6 H), 4.16 (br d, J = 9.2 Hz, 1 H), 4.12-4.08 (m,
1 H), 3.87 (s, 3 H), 3.80 (s, 3 H), 3.89-3.86 (m, 1 H), 3.81-3.78
1:1:1) to afford 12 (31 mg, 85%) as a white solid: mp 80-81 °C;
D
1
[R]28 þ23.1 (c 0.52, CHCl3); H NMR (300 MHz, CDCl3) δ
7.87 (d, J = 4.2 Hz, 1 H), 7.39-6.87 (m, 20 H), 6.80 (s, 1 H), 6.35
(s, 1 H), 6.07 (d, J = 6.9 Hz, 1 H), 4.90-4.77 (m, 3 H), 4.63-4.42
(m, 5 H), 4.27 (d, J = 11.7 Hz, 2 H), 4.11-4.03 (m, 1 H), 4.03 (s, 3
H), 3.93-3.86 (m, 1 H), 3.86 (s, 3 H), 3.73 (s, 2 H), 3.50 (s, 3 H);
13C NMR (100 MHz, CDCl3) δ 175.4, 162.6, 162.0, 157.7, 152.4,
150.0, 143.0, 138.7, 138.5, 138.1, 137.8, 128.4, 128.3, 128.24,
128.20, 128.01, 127.96, 127.93, 127.8, 127.72, 127.66, 127.53,
127.45, 116.3, 109.5, 107.0, 98.9, 90.7, 82.4, 79.5, 78.6, 74.3, 74.1,
73.8, 73.6, 73.0, 70.0, 68.2, 56.3, 56.04, 55.95; ESIMS (m/z) 825
[M þ H]þ, 847 [M þ Na]þ; HRMS (MALDI) calcd for
C50H49O11 [M þ H]þ 825.3269, found 825.3268.
(m, 1 H), 3.73-3.65 (m, 3 H), 3.27 (br s, 3 H), 3.11 (s, 3 H); 13
C
NMR (100 MHz, CDCl3) δ 158.5, 157.6, 151.1, 150.6, 150.4,
139.1, 138.7, 138.32, 138.25, 133.6, 128.4, 128.33, 128.29, 128.24,
128.22, 128.0, 127.93, 127.91, 127.88, 127.6, 127.5, 127.3, 124.1,
112.7, 107.3, 101.81, 101.76, 90.6, 83.1, 79.9, 78.8, 74.7, 74.2,
73.9, 73.5, 72.6, 70.0, 68.0, 56.3, 55.7, 55.6, 38.1, 21.7; ESIMS
(m/z) 911 [M þ Na]þ; HRMS (MALDI) calcd for C51H52O12S-
Na [M þ Na]þ 911.3072, found 911.3077. 9: mp 62-63 °C;
1
[R]28 þ48.3 (c 0.74, CHCl3); H NMR (400 MHz, CDCl3) δ
4-C-β-D-Glucopyranosyl-3-methoxy-1,6,7-trihydroxyxanthone
(14). To a solution of 12 (40 mg, 0.049 mmol) in anhydrous
CH2Cl2 (1.5 mL) was added BBr3 (1N in CH2Cl2, 0.97 mL) at
0 °C. The mixture was allowed to warm to room temperature.
After 3 h, the reaction was quenched with water. The mixture
was concentrated in vacuo. The residue was purified by column
chromatography on Sephadex LH-20 (CH2Cl2/MeOH = 1:1)
to afford 14 (21 mg, 100%) as a yellow solid: mp 183-184 °C;
[R]24D þ7.8 (c 0.36, CH3OH); 1H NMR (400 MHz, CD3OD) δ
7.35 (d, J = 12.0 Hz, 1 H), 6.86/6.79 (s, 1 H), 6.39 (d, J = 9.2 Hz,
1 H), 5.02/4.93 (d, J = 10.4 Hz, 1 H), 4.35-4.29 (m, 1 H),
3.93-3.91 (m, 1 H), 3.91 (s, 3 H), 3.73-3.67 (m, 1 H), 3.58-3.49
(m, 2 H), 3.43-3.40 (m, 1 H); 13C NMR (100 MHz, CD3OD) δ
181.8/181.7, 166.2/167.2, 165.1/164.9, 157.7, 155.7, 153.4, 145.2/
145.1, 113.7, 109.3/109.2, 105.8/105.5, 104.3, 103.9/103.7, 95.0/
95.9, 82.6/82.8, 80.5/80.7, 74.9/75.4, 73.1, 72.7/72.5, 63.8/63.7,
57.1/56.9; ESIMS (m/z) 825 [M - 1]þ; HRMS (ESI) calcd for
C20H19O11 [M - 1]þ 435.0933, found 435.0922.
D
7.35-6.95 (m, 21 H), 6.68 (s, 1 H), 6.40 (s, 1 H), 5.77 (d, J = 6.6
Hz, 1 H), 4.88-4.74 (m, 3 H), 4.59-4.20 (m, 6 H), 4.04-3.96 (m,
2 H), 3.88 (s, 3 H), 3.78 (s, 3 H), 3.70 (s, 3 H), 3.90-3.63 (m, 5 H),
3.18 (s, 3 H); 13C NMR (100 MHz, CDCl3) δ 159.0, 158.2, 152.2,
150.8, 150.6, 138.9, 138.8, 138.4, 138.2, 133.8, 128.29, 128.25,
128.20, 128.0, 127.9, 127.84, 127.81, 127.7, 127.5, 127.4, 124.6,
115.8, 112.5, 106.6, 101.4, 96.3, 83.0, 80.2, 78.2, 74.0, 73.9, 73.3,
72.7, 70.1, 69.6, 62.1, 56.2, 55.7, 53.9, 38.1, 22.2; ESIMS (m/z)
911 [M þ Na]þ; HRMS (MALDI) calcd for C51H52O12SNa [M
þ Na]þ 911.3072, found 911.3085.
4-C-(2,3,4,6-Tetra-O-benzyl-β-D-glucopyranosyl)-7-mesyloxy-
1,3,6-trimethoxyxanthone (10). To a solution of 8 (141 mg, 0.16
mmol) in CH2Cl2/1,4-dioxane/H2O (8/4/1, 10.4 mL) was added
DDQ (360 mg, 1.6 mmol) at 0 °C. The reaction mixture was
allowed to warm to room temperature and stirred for 4 h. After
the mixture was diluted with EtOAc, DMAP (290 mg, 2.38
mmol) was added. The precipitate was filtered through a Celite
pad. The filtrate was concentrated in vacuo. The residue was
purified by silica gel column chromatography (petroleum ether/
CH2Cl2/EtOAc = 3:2:2) to afford 10 (117 mg, 82%) as a white
solid: mp 61-62 °C; [R]28D þ29.6 (c 0.60, CHCl3); 1H NMR (400
MHz, CDCl3) δ 8.07 (s, 1 H), 7.39-6.85 (m, 21 H), 6.37 (s, 1 H),
6.04 (d, J = 6.8 Hz, 1 H), 4.86-4.76 (m, 3 H), 4.61-4.55 (m, 2
H), 4.50-4.46 (m, 2 H), 4.38-4.35 (m, 1 H), 4.30 (br d, J = 9.6
Hz, 1 H); 4.22 (d, J = 11.2 Hz, 1 H); 4.06-4.03 (m, 1 H), 4.03 (s,
3 H), 3.92-3.87 (m, 1 H), 3.87 (s, 3 H), 3.74 (d, J = 2.8 Hz, 2 H),
3.47 (br s, 3 H), 3.20(s, 3 H); 13C NMR (100 MHz, CDCl3) δ
174.4, 162.9, 162.0, 157.6, 156.6, 154.4, 138.5, 138.3, 138.1,
137.7, 135.5, 128.5, 128.4, 128.3, 128.02, 127.96, 127.90,
Acknowledgment. Financial support from the National
Natural Science Foundation of China (20932009, 20621062),
the Ministry of Science and Technology of China
(2009ZX09311), and the E-Institutes of Shanghai Municipal
Education Commission (E09013) is gratefully acknowledged.
Supporting Information Available: Experimental details,
characterization data, and the 1H and 13C NMR spectra for all
new compounds. This material is available free of charge via the
5728 J. Org. Chem. Vol. 75, No. 16, 2010