2058
Y. Matsuo et al. / Tetrahedron 67 (2011) 2051e2059
aq MeOH) and Sephadex LH-20 (0e100% aq MeOH), to give
(ꢀ)-epigallocatechin-3-O-acetate (10) (1.49 g, 60%).
brown amorphous powder; [
a
]
29 ꢀ76.4 (c 0.10, MeOH); FABMS m/
D
z: 695 [MþH]þ; HRFABMS m/z: [MþH]þ calcd for C34H31O16
,
695.1612; found: 695.1628; UV (MeOH) lmax nm (log 3): 209 (4.95),
4.7.1. (ꢀ)-Epigallocatechin-3-O-acetate (10). A white amorphous
236 sh (4.35), 274 sh (3.49); IR (dry film) nmax cmꢀ1: 3403, 1717,
19
powder, [
a
]
D
ꢀ62.0 (c 0.11, MeOH); HRFABMS m/z: [MþH]þ calcd
1631, 1518, 1467, 1378; 1H NMR (400 MHz, acetone-d6)
d
: 1.88 (6H,
for C17H17O8, 349.0923; found, 349.0910; UV (MeOH) lmax nm
s, Ac), 2.52 (2H, dd, J¼17.6, 4.9 Hz, H-4), 2.73 (2H, br d, J¼17.6 Hz, H-
4), 4.69 (2H, s, H-2), 5.13 (2H, m, H-3), 5.86, 5.98 (each 2H, d,
J¼2.2 Hz, H-6, 8), 6.78 (2H, s, H-60), 7.03, 7.53, 7.90, 8.09, 8.26 (each
(log
3
): 270 (3.32); IR (dry film) nmax cmꢀ1: 3340, 1711, 1605, 1513,
: 1.86 (3H, s, Ac), 2.76
1461, 1377; 1H NMR (acetone-d6, 400 MHz)
d
(1H, dd, J¼17.6, 2.4 Hz, H-4), 2.95 (1H, dd, J¼17.6, 4.9 Hz, H-4), 4.94
(1H, s, H-2), 5.36 (1H, m, H-3), 5.94, 6.04 (each 1H, d, J¼2.4 Hz, H-6,
8), 6.54 (2H, s, H-20, 60), 7.30 (1H, br s, OH at C-40), 7.87 (2H, s, OH at
C-30, 50), 8.13, 8.34 (each 1H, s, OH at C-5, 7); 13C NMR (acetone-d6,
2H, br s, OH at C-5, 7, 30, 40, 50); 13C NMR (100 MHz, acetone-d6)
d:
21.0 (Ac(CH3)), 26.4 (C-4), 68.3 (C-3), 75.5 (C-2), 95.8, 96.5 (C-6, 8),
98.3 (C-4a), 107.9 (C-60), 111.5 (C-20), 129.1 (C-10), 133.9 (C-40),
144.8, 146.5 (C-30, 50), 157.0, 157.3, 157.8 (C-5, 7, 8a), 171.3 (Ac(CO)).
100 MHz) d: 20.9 (Ac(CH3)), 26.3 (C-4), 68.9 (C-3), 77.7 (C-2), 95.8,
96.4 (C-6, 8), 98.9 (C-4a), 106.7 (2C, C-20, 60), 130.5 (C-10), 133.2 (C-
40), 146.2 (2C, C-30, 50), 156,9, 157.4, 157.8 (C-5, 7, 8a), 170.3 (Ac(CO)).
4.8.1.2. Acetylation of 11a. A solution of 11a (20.3 mg, 29 mmol)
in a mixture of acetic anhydride (0.5 mL) and pyridine (0.5 mL) was
stirred for 20 h. After stirring, the solution was poured into ice-cold
water and filtered. The filtered residue was purified by column
chromatography on silica gel (CHCl3eMeOH, 100:0e98:2) to give
11b (20.5 mg, 63%). By the same procedure, acetylation of the-
4.8. Enzymatic oxidation of (L)-epigallocatechin-3-O-acetate
(10)
Japanese pear fruits (100 g) were homogenized with 100 mL of
H2O and filtered through four layers of gauze. The filtrate (93 mL)
was mixed with an aqueous solution of (ꢀ)-epigallocatechin-3-O-
acetate (10) (930 mg/93 mL) and vigorously stirred for 60 min at
room temperature. After stirring, the reaction solution was acidi-
fied with TFA (0.5 mL) and insoluble materials were removed by
filtration. The filtrate was directly applied to a column of MCI-gel
CHP-20P (3ꢂ29 cm) and eluted with 0e100% aq MeOH containing
0.1% TFA (5% stepwise elution, each 200 mL) to yield five fractions
(fr. 1e5). Each fraction was concentrated in vacuo below 40 ꢁC and
lyophilized. Fr. 1 (420.1 mg) was pure compound 11. Fr. 2 (57.2 mg)
was subjected to Chromatorex ODS (2ꢂ27 cm, 0e60% aq MeOH
containing 0.1% TFA) column chromatography to give 12 (10.8 mg).
asinensin C (14) (26.9 mg, 44 mmol) also afforded 11b (29.8 mg, 61%).
33
A white amorphous powder; [
a
]
þ17.7 (c 0.12, CHCl3); MALDI-
D
TOFMS m/z: 1137 [MþNa]þ, 1153 [MþK]þ; Anal. Calcd for
C54H50O26$H2O: C, 57.25; H, 4.63. Found: C, 57.33; H, 4.61; UV
(MeOH) lmax nm (log
nmax cmꢀ1: 2925, 2853, 1771, 1744, 1624, 1593, 1487, 1438, 1370; 1H
NMR (400 MHz, CDCl3) : 1.978, 1.985, 2.228, 2.235, 2.25, 2.27 (each
3): 206 (4.92), 270 (3.38); IR (dry film)
d
6H, s, Ac), 2.72 (4H, br s, H-4), 4.61 (2H, s, H-2), 5.40 (2H, br s, H-3),
6.49, 6.53 (each 2H, d, J¼2.4 Hz, H-6, 8), 7.62 (2H, s, H-60); 13C NMR
(100 MHz, CDCl3) d: 19.7, 20.1, 20.7, 20.7, 20.8, 21.0 (Ac(CH3)), 26.0 (C-
4), 65.0 (C-3), 74.1 (C-2),108.0,108.7,109.7 (C-4a, 6, 8),121.7,122.9 (C-
20, 60),134.7,135.3 (C-10, 40),141.7,143.6 (C-30, 50),149.4,149.5 (C-5, 7),
155.0 (C-8a), 166.5, 167.3, 167.6, 168.5, 169.0, 170.3 (Ac(CO)).
Fr.
3 (217.4 mg) was separated by Cosmosil 40C18-PREP
(20ꢂ300 mm, 4e30% aq CH3CN) and the same column (4e60% aq
4.8.2. Compound 12. A tan amorphous powder; [
a
]
16 ꢀ33.7 (c 0.10,
D
MeOH) to afford 13a (18.5 mg) and 12 (10.7 mg).
MeOH); FABMS m/z: 711 [MþH]þ; HRFABMS m/z: [MþH]þ calcd
for C34H31O17, 711.1561; found, 711.1570; UV (MeOH) lmax nm
30
4.8.1. Compound 11. A white amorphous powder; [
a
]
ꢀ132.4
(log
3): 206 (4.72), 228 sh (4.27), 268 sh (3.60); IR (dry film)
(c 0.095, MeOH); FABMS m/z: 711 [MþH]þ, 733 [MþDNa]þ, 749
nmax cmꢀ1: 3390, 1719, 1673, 1629, 1607, 1519, 1469; 1H NMR
[MþK]þ, 693 [MꢀH2OþH]þ; HRFABMS m/z: [MþH]þ calcd for
(500 MHz, acetone-d6)
d
: 1.87 (6H, s, Ac), 2.83 (2H, dd, J¼17.5,
C34H31O17, 711.1561; found, 711.1558; UV (MeOH) lmax nm (log
3):
2.0 Hz, H-4), 2.93 (2H, dd, J¼17.5, 4.7 Hz, H-4), 3.29 (2H, s, H-20),
4.56 (2H, br s, H-2), 5.63 (2H, m, H-3), 6.01, 6.07 (each 2H, d,
J¼2.3 Hz, H-6, 8), 6.44 (2H, d, J¼1.6 Hz, H-60); 13C NMR (125 MHz,
269 (3.56), 305 (3.30); IR (dry film) nmax cmꢀ1: 3407, 1724, 1633,
1519, 1469, 1379; 1H NMR (500 MHz, acetone-d6) : 1.85 (3H, s, 300-
d
OAc), 1.88 (3H, s, 3-OAc), 2.73 (1H, br d, J¼16.9 Hz, H-4), 2.83 (1H,
dd, J¼16.9, 4.6 Hz, H-4), 2.86 (1H, br d, J¼17.0 Hz, H-400), 3.02 (1H,
dd, J¼17.0, 4.5 Hz, H-400), 4.37 (1H, s, H-20), 4.87 (1H, br s, H-2), 5.29
(1H, m, H-3), 5.42 (1H, m, H-300), 5.71 (1H, br s, H-200), 5.93, 5.96,
5.98, 6.00 (each 1H, d, J¼1.6 Hz, H-6, 8, 600, 800), 6.20 (1H, s, H-60),
acetone-d6) d
: 20.7 (Ac(CH3)), 25.7 (C-4), 59.9 (C-20), 64.7 (C-3),
76.4 (C-2), 85.4 (C-40), 95.7, 96.8 (C-6, 8), 98.3 (C-4a), 104.7 (C-30),
126.9 (C-60), 155.3, 157.2 (C-5, 8a), 156.6 (C-10), 157.9 (C-7), 170.3
(Ac(CO)), 196.6 (C-50); HMBC correlations (H to C): H-2/C-4, 10, 20,
60; H-3/C-4, 4a, Ac(CO); H-4/C-2, 3, 4a, 5, 6 (4J), 8 (4J), 8a; H-6, 8/C-
4a, 7, 5 or 8a, 8 or 6; H-20/C-2, 10, 30, 40, 50, 60; H-60/C-2, 10, 20, 30 (4J),
40; H-Ac/C-3 (4J), Ac(CO).
6.85 (1H, s, H-6000); 13C NMR (125 MHz, acetone-d6)
d: 20.8, 20.9 (3-,
300-OAc(CH3)), 26.4 (C-400), 26.6 (C-4), 45.5 (C-20), 67.8 (C-3), 68.6 (C-
300), 74.3 (C-200), 76.9 (C-2), 92.0 (C-30), 95.7, 95.8, 96.3, 96.8 (C-6, 8,
600, 800), 96.6 (C-40), 98.5 (C-4a00), 98.6 (C-4a), 109.2 (C-6000), 111.9 (C-
30
4.8.3. Compound 13a. A pale yellow amorphous powder; [a]
D
2
5
000), 122.9 (C-60), 127.4 (C-1000), 133.4 (C-4000), 142.8 (C-3000), 146.0 (C-
000), 155.4, 156.7, 157.1 (2C) (C-5, 8a, 500, 8a00), 157.6 (2C, C-7, 700),
þ61.5 (c 0.12, MeOH); FABMS m/z: 471 [MþH]þ, 493 [MþNa]þ, 941
[2MþH]þ; HRFABMS m/z: [MþH]þ calcd for C23H19O11, 471.0927;
162.0 (C-10), 169.9 (3-OAc(CO)), 170.6 (300-OAc(CO)), 191.5 (C-50);
HMBC correlations (H to C): H-2/C-3, 4, 10, 20, 60; H-3/C-4a, 3-OAc
(CO); H-4/C-2, 3, 4a, 5, 8a; H-20/C-2,10, 30, 40, 50 (4J), 60,1000, 2000, 3000, 4000
(4J); H-60/C-2, 10, 20, 30 (4J), 40, 2000 (4J); H-200/C-300, 400, 1000, 2000, 6000; H-
300/C-4a00, 300-OAc(CO); H-400/C-200, 300, 4a00, 500, 8a00; H-6000/C-20 (4J), 200,
1000, 2000, 3000 (4J), 4000, 5000; H-3-OAc/C-3 (4J), 3-OAc(CO); H-300-OAc/C-
300 (4J), 300-OAc(CO).
found: 471.0930; UV (MeOH) lmax nm (log 3): 277 sh (3.79), 300
(3.82), 346 sh (3.45); IR (dry film) nmax cmꢀ1: 3346, 1711, 1683, 1606,
1509, 1471, 1339; 1H NMR (500 MHz, acetone-d6)
: 1.98 (3H, s, Ac),
d
2.85 (1H, dd, J¼17.5, 2.9 Hz, H-4), 3.00 (1H, d, J¼17.5, 4.9 Hz, H-4),
4.48 (1H, s, H-e), 5.17 (1H, br s, H-2), 5.70 (1H, m, H-3), 5.93 (1H, br
s, H-c), 6.14 (1H, d, J¼2.3 Hz, H-6), 6.18 (1H, d, J¼2.3 Hz, H-8), 6.92
(1H, s, H-f); 13C NMR (125 MHz, acetone-d6)
d: 20.9 (Ac(CH3)), 25.9
(C-4), 55.7 (C-e), 66.5 (C-3), 74.0 (C-2), 85.4 (C-a), 95.9 (C-8), 97.3
(C-6), 99.2 (C-8a), 106.8 (C-f), 114.2 (C-j), 126.0 (C-c), 133.0 (C-h),
143.2 (C-k), 146.6 (C-g), 155.5 (C-8a), 156.1 (C-i), 157.6 (C-5), 158.1
(C-7), 170.7 (Ac(CO)), 174.9 (C-d), 198.7 (C-l), 200.7 (C-b); HMBC
correlations (H to C): H-2/C-4, 8a, b (4J), c, d; H-3/C-4, 4a, d, Ac(CO);
H-4/C-2, 3, 4a, 5, 6 (4J), 8 (4J), 8a; H-6/C-4a, 5, 7, 8; H-8/C-4a, 6, 7, 8a;
4.8.1.1. Reduction of 11 with dithiothreitol. To a solution of 11
(55.5 mg, 78
mmol) in H2O (20 mL) was added dithiothreitol
(50 mg) and the mixture was stirred at room temperature for 2 h.
The solution was directly applied to MCI-gel CHP20P (2ꢂ23 cm)
and eluted with 0e70% aq MeOH to give 11a (31.0 mg, 57%). A pale