Synthesis of 3-O-(β-d-xylopyranosyl-(1→2)-β-d-glucopyranosyl)-3′-O-(β-d-glucopyranosyl)tamarixetin, the putative structure of aescuflavoside A from the seeds of Aesculus chinensis

Article abstract of DOI:10.1016/j.carres.2006.02.036

3-O-(β-d-Xylopyranosyl-(1→2)-β-d-glucopyranosyl)-3′-O-(β-d-glucopyranosyl)tamarixetin, the putative flavonal glycoside named aescuflavoside A, isolated from the seeds of Aesculus chinensis, is synthesized via regioselective glycosylation of 7-O-benzyltama

Full text of DOI:10.1016/j.carres.2006.02.036

Carbohydrate Research 341 (2006) 1047–1051
Note
Synthesis of 3-O-(b-D-xylopyranosyl-(1!2)-b-D-glucopyranosyl)-30-
O-(b-D-glucopyranosyl)tamarixetin, the putative structure of
aescuflavoside A from the seeds of Aesculus chinensis
Cunsheng Zhu,a Wenjie Peng,b Yuwen Li,a Xiuwen Hanb and Biao Yua,*
aState Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry,
Chinese Academy of Sciences, Shanghai 200032, China
bState Key Laboratory of Catalyst, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
Received 12 January 2006; received in revised form 24 February 2006; accepted 26 February 2006
Available online 3 April 2006
Abstract—3-O-(b-D-Xylopyranosyl-(1!2)-b-D-glucopyranosyl)-30-O-(b-D-glucopyranosyl)tamarixetin, the putative flavonal glyco-
side named aescuflavoside A, isolated from the seeds of Aesculus chinensis, is synthesized via regioselective glycosylation of 7-O-benz-
yltamarixetin with glycosyl bromides under phase-transfer-catalyzed conditions.
Ó 2006 Elsevier Ltd. All rights reserved.
Keywords: Flavonol glycoside; Tamarixetin; Aescuflavoside A; Glycosylation; Synthesis
Quercetin glycosides are abundant in plants; their 30-O-
methyl (isorhamnetin) derivatives are not uncommon.
However, 40-O-methyl quercetin (tamarixein) glycosides
are rare in nature.1 3-O-(b-D-Xylopyranosyl-(1!2)-b-D-
glucopyranosyl)-30-O-(b-D-glucopyranosyl) tamarixetin
(1), known as aescuflavoside A, was assigned for a flavo-
nol glycoside isolated from the seeds of Aesculus chinen-
sis Bge. (Hippocastanaceae), the source of a traditional
Chinese medicine.2 This compound was claimed to pos-
sess potent antiviral activity against respiratory syn-
cytial virus (RSV), with an IC50 value of 6.7 lg/mL
and selective index (SI) value of 32 (in HEp2 cells) that
is comparable to that of the approved drug ribavirin.2 In
line with our preceding reports on the synthesis of flavo-
noid glycosides,3 herein we describe the synthesis of
compound 1.
We have recently developed an efficient method for
the preparation of 7-O-benzyltamarixetin from the
widely available quercetin.3a Glycosylation of the flavo-
nol 3,30,5-triol with an a-glycosyl bromide under mild
phase-transfer-catalyzed (PTC) conditions afforded the
corresponding 3-O-b-glycoside in a highly regioselective
manner.3,4 The remaining 30-OH is then more suscepti-
ble to glycosylation (substitution) than the hydrogen-
bonded 5-OH.5
Following the above rationale, we set out on the prep-
aration of the required glycosyl bromide (7, Scheme 1).
Thus, the readily available 3,4,6-tri-O-acetyl-1,2-O-(1-
ethoxyethylidene)-a-D-glucopyranose (2)6 was subjected
to deacetylation (NaOEt–EtOH) and benzylation to pro-
vide 1,2-orthoacetate 3 in high yield (93%).7 When the
deacetylation was carried out with NaOMe–HOMe,8
partial conversion of the 1,2-O-(1-ethoxyethylidene) into
4'
OMe
7
HO
O
3'
O
1'''O' H
3
O
O
HO
OH
O
1''
O
OH
OH
O
1'''
O
OH
HO
OH
OH
OH
OH
1
*
Corresponding author. Tel.: +86 21 54925131; fax: +86 21
64166128; e-mail: byu@mail.sioc.ac.cn
0008-6215/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2006.02.036

1048
C. Zhu et al. / Carbohydrate Research 341 (2006) 1047–1051
BnO
BnO
BnO
BnO
BnO
BnO
AcO
AcO
O
O
O
c
O
a, b
BnO
+
BnO
BnO
AcO
O
OH
AcO
4b
O
O
OH
O
OAc
4a
3
2
OEt
OEt
O
BzO
BzO
O
CCl3
NH
d
OBz
5
OMe
OH
BnO
BnO
O
O
BnO
BnO
BnO
O
O
e
BnO
BnO
+
O
O
O
O
Br
BzO
BzO
BzO
OAc
BzO
OH
OBz
OBz
6
OH
7
8
f
OMe
OMe
OH
BnO
O
O
BnO
O
O
O
O
O
OBz
O
h, i
g
OH
1
OH
O
O
BzO
BzO
O
O
BzO
OBz
OBz
OBz
O
BnO
BnO
OBn
BnO
BzO
O
O
OBn
BnO
BzO
Br
OBz
11
10
9
OBz
BzO
OBz
BzO
Scheme 1. Reagents and conditions: (a) NaOEt–EtOH, rt; (b) BnBr, NaH, DMF, 0 °C!rt, 93% (based on 2); (c) 0.8 N H2SO4, 5:1 acetone–H2O, rt,
˚
4a/4b = 4:1; (d) TMSOTf (0.3 equiv), CH2Cl2, 4 A MS, ꢀ20 °C, 80% (based on 3); (e) HBr–HOAc, CH2Cl2, rt; (f) K2CO3, TBAB, CHCl3–H2O,
50 °C, 44% (for two steps); (g) NaOH, TBAB, CHCl3–H2O, 50 °C, 84%; (h) H2, 10% Pd/C, EtOH–EtOAc, 45 °C; (i) NaOMe, MeOH–CH2Cl2, rt,
40% (based on 11).
the corresponding methyl orthoacetate was observed.
The regioselectivity in opening of the glucose 1,2-ortho-
acetate by acid-catalyzed hydrolysis was found to be
highly dependent on the reaction conditions.9 Adopting
a modification of the literature conditions,9 we treated
compound 3 with 0.8 N H2SO4 in 5:1 acetone–H2O at
rt. An inseparable mixture containing the expected
1- and 2-acetate 4a and 4b was produced, where the ratio
disaccharide bromide 7 afforded the desired 3-O-glyco-
side 9 (H-100: 5.87 ppm, d, J 7.8 Hz) in a good (44%) yield
(for two steps based on 6). Subsequent glycosylation of
the 30,5-diol 9 with 2,3,4,6-tetra-O-benzoyl-a-D-gluco-
pyranosyl bromide (10)12 under stronger PTC conditions
with NaOH as a base provided the desired 3,30-diglyco-
side 11 (H-100: 5.93 ppm, d, J 7.5 Hz; H-10000: 5.73 ppm,
d, J 8.1 Hz) in 84% yield. Finally, deprotection of the
benzyl groups (H2, Pd/C) and benzoyl groups (NaOMe)
in 11 cleanly furnished the target flavonol glycoside 1
(40%).
Alternatively, the protected tamarixetin 3,30-diglyco-
side 11 was prepared via a later installation of the termi-
nal D-xylose residue (Scheme 2). Thus, 1,2-orthoacetate
3 was readily converted into 2-O-acetyl-3,4,6-tri-O-benz-
yl-a-D-glucopyranosyl bromide (12).7 Treatment of
bromide 12 with 3,30,5-triol 8 under similar PTC condi-
tions for 7!9 provided the 3-O-glycoside 13 in a better
86% yield. Then, regioselective glycosylation of 30,5-diol
13 with glucopyranosyl bromide 10 under similar condi-
tions for 9!11 furnished the 3,30-diglycoside 14 in a
comparable 80% yield. Selective removal of the 200-O-
acetyl group in 14 was examined with HCl in MeOH–
CH2Cl2.13 The desired product 15 was isolated in a mod-
1
of 4a/4b was determined to be 4:1 by H NMR integra-
tion (H-1 for 4a: 6.22 ppm, d, J 2.4 Hz; H-1 for 4b:
5.35 ppm, br s). Fortunately, treatment of the mixture
with 2,3,4-tri-O-benzoyl-D-xylopyranosyl trichloroacet-
imidate (5)10 in the presence of TMSOTf (0.3 equiv)
provided the desired disaccharide 6 (H-10: 5.13 ppm, d,
J 5.7 Hz) in a satisfactory isolated yield (85% for two
steps). We had tried the coupling with 2,3,4-tri-O-acet-
yl-D-xylopyranosyl trichloroacetimidate11 under similar
conditions, but a complex mixture resulted. The disac-
charide bromide 7, readily generated from acetate 6,
was found unstable upon silica gel chromatography
and was therefore directly subjected to the PTC glycosyl-
ation with 7-O-benzyltamarixetin (8). Under similar con-
ditions described before (K2CO3, Bu4N+Brꢀ (TBAB),
CHCl3/H2O, 50 °C),3a coupling of triol 8 with the crude

C. Zhu et al. / Carbohydrate Research 341 (2006) 1047–1051
1049
OMe
OMe
O
BnO
O
O
BnO
O
O
OH
BnO
BnO
b
a
O
O
O
OBz
O
BnO
OH
OH
10
O
8
O
AcO
Br
OAc
OAc
BzO
12
OBz
OBz
BnO
BnO
13
OBn
OBn
14
BnO
BnO
OMe
BnO
O
O
O
d
c
O
11
OBz
O
OH
5
O
OH
BzO
OBz
OBz
BnO
OBn
BnO
15
Scheme 2. Reagents and conditions: (a) K2CO3, TBAB, CHCl3–H2O, 50 °C, 86%; (b) NaOH, TBAB, CHCl3–H2O, 50 °C, 80%; (c) AcCl, MeOH,
˚
CH2Cl2, 0 °C to rt, 31%; (d) TBSOTf (0.3 equiv), CH2Cl2, 4 A MS, rt, 83%.
erate 31% yield, where cleavage of the 30-O-glycosidic
linkage was detected. Coupling of 15 with xylopyranosyl
trichloroacetimidate 5 was accomplished under the pro-
motion of TBSOTf (0.3 equiv), providing 11 in 83%
yield.
of the above product (99 mg, 0.201 mmol), imidate 5
(366 mg, 0.603 mmol), and 4 A molecular sieves in an-
˚
hyd CH2Cl2 (5 mL) was added a solution of TMSOTf
in CH2Cl2 (0.10 M, 0.60 mL, 0.060 mmol) at ꢀ20 °C
under argon. Stirring was continued until TLC indicated
completion of the reaction. The mixture was then neu-
tralized with Et3N and filtered. The filtrates were con-
centrated to give a residue that was purified by silica
gel column chromatography (4:1 petroleum ether–
EtOAc) to give 6 (161 mg, 80% from 3) as a white foam:
1
However, the H and 13C NMR signals of the syn-
thetic sample (1) disagree with those reported for the
natural product, aescuflavoside A. HBMC analysis of
compound 1 supports the synthetic structure, where
correlations are clearly observed between the diagnostic
H-10000 (4.99 ppm, d, J 6.7 Hz) and C-30 (146.3 ppm), H–
OMe (3.86 ppm, s) and C-40 (151.6 ppm). Because
detailed assignments for the structure of natural aescufla-
voside A have not been provided, the reasons for the
present discrepancy are unclear.
23
½aꢁD +15 (c 1.22, CHCl3); 1H NMR (CDCl3, 300 MHz):
d 7.99 (d, J 8.4 Hz, 2H), 7.94 (d, J 8.7 Hz, 2H), 7.84 (d, J
8.4 Hz, 2H), 7.57–7.16 (m, 20H), 7.13–7.05 (m, 2H),
7.04–7.02 (m, 2H), 6.39 (d, J 2.4 Hz, 1H), 5.75 (t,
J 7.5 Hz, 1H), 5.47 (dd, J 5.7, 7.5 Hz, 1H), 5.36–5.28
(m, 1H), 5.13 (d, J 5.7 Hz, 1H), 4.73–4.42 (m, 6H),
4.38 (dd, J 4.2, 12.0 Hz, 1H), 3.92 (d, J 5.1 Hz, 2H),
3.84–3.63 (m, 5H), 2.11 (s, 3H); ESIMS (m/z): 959
1. Experimental
1.1. General methods
See Ref. 14.
(M+Na+),
976
(M+K+).
Anal.
Calcd
for
C55H52O14Æ0.5H2O: C, 69.83; H, 5.65. Found: C,
70.12; H, 5.84.
1.3. 7-O-Benzyl-3-O-(2,3,4-tri-O-benzoyl-b-D-xylopyr-
anosyl-(1!2)-3,4,6-tri-O-benzyl-b-D-glucopyranosyl)-
tamarixetin (9)
1.2. 2,3,4-Tri-O-benzoyl-b-D-xylopyranosyl-(1!2)-1-O-
acetyl-3,4,6-tri-O-benzyl-a-D-glucopyranose (6)
To a stirred solution of 3 (109 mg, 0.21 mmol) in 5:1
EtOH–EtOAc (6 mL) was added 98% H2SO4
(0.13 mL, 2.39 mmol). Stirring was continued until
TLC indicated completion of the reaction. The mixture
was then neutralized with NaHCO3 and extracted with
CH2Cl2. The organic layer was washed with brine, dried
over Na2SO4, and concentrated in vacuo to give 4
(99 mg, 4a/4b = 4:1) as a colorless syrup. To a mixture
To a cooled solution of disaccharide acetate 6 (113 mg,
0.12 mmol) in anhyd CH2Cl2 (10 mL) at 0 °C was added
a solution of 33% HBr in HOAc (0.19 mL, 1.09 mmol).
After stirring for 6 h, the mixture was neutralized with
NaHCO3. The organic layer was washed with cooled
brine, dried over Na2SO4, and then concentrated in
vacuo, providing the crude bromide 7 (118 mg) as a
white foam. The crude 7 (60 mg) was dissolved in CHCl3

1050
C. Zhu et al. / Carbohydrate Research 341 (2006) 1047–1051
(2 mL), and then TBAB (38 mg, 0.118 mmol), K2CO3
(21 mg, 0.148 mmol), and H2O (2 mL) were added.
The resulting mixture was stirred at 50 °C for 20 h,
and then neutralized with addition of 1 N HCl. The
organic layer was washed with brine, dried over
Na2SO4, and concentrated in vacuo. The residue was
purified by preparative TLC (8:1 toluene–EtOAc) to
afford 9 (68 mg, 44% based on 6) as a yellow foam:
0.09 mmol), and K2CO3 (16 mg, 0.11 mmol) in 1:1
CHCl3–H2O (4 mL) was stirred at 50 °C for 7 h. After
neutralization with addition of 1 N HCl, the organic
layer was washed with brine, dried over Na2SO4, and
concentrated in vacuo. The residue was purified by pre-
parative TLC (6:1 toluene–EtOAc) to afford 13 (76 mg,
23
1
86%) as a yellow foam: ½aꢁD ꢀ54 (c 0.43, CHCl3); H
NMR (CDCl3, 300 MHz): d 12.55 (s, 1H, 5-OH), 7.81
(dd, J 2.1, 8.4 Hz, 1H), 7.67 (d, J 2.1 Hz, 1H), 7.44–
7.20 (m, 18H), 7.12–7.09 (m, 2H), 6.78 (d, J 8.4 Hz,
1H), 6.52 (d, J 2.1 Hz, 1H), 6.44 (d, J 2.1 Hz, 1H),
5.75 (s, 1H, 30-OH), 5.51 (d, J 7.8 Hz, 1H), 5.32–5.25
(m, 1H), 5.14 (s, 2H), 4.87–4.73 (m, 3H), 4.61 (d, J
10.8 Hz, 1H), 4.24 (d, J 11.7 Hz, 1H), 4.08 (d, J
11.7 Hz, 1H), 3.82–3.69 (m, 6H), 3.55 (d, J 11.7 Hz,
1H), 3.50–3.40 (m, 1H), 2.13 (s, 3H); 13C NMR (CDCl3,
75 MHz): d 177.9, 170.2, 164.5, 162.0, 157.2, 156.7,
138.4, 138.3, 138.1, 135.9, 134.1, 128.7, 128.4, 128.3,
128.1, 127.9, 127.7, 127.4, 127.3, 123.4, 115.4, 110.2,
106.1, 99.2, 98.8, 93.0, 82.8, 77.9, 76.0, 75.2, 74.9, 73.9,
73.5, 70.4, 68.6, 55.7, 21.1; HRESIMS (m/z): calcd for
C52H48NaO13 (M+Na+): 903.2987. Found: 903.2991.
23
½aꢁD ꢀ96 (c 0.56, CHCl3); 1H NMR (CDCl3, 300
MHz): d 12.70 (s, 1H, 5-OH), 8.24 (d, J 6.6 Hz, 2H),
7.95 (t, J 8.4 Hz, 4H), 7.80 (dd, J 1.8, 9.0 Hz, 1H),
7.71 (d, J 1.8 Hz, 1H), 7.60–7.07 (m, 29H), 6.80 (d, J
9.0 Hz, 1H), 6.53 (d, J 1.8 Hz, 1H), 6.45 (d, J 1.8 Hz,
1H), 5.87 (d, J 7.8 Hz, 1H), 5.66 (m, 2H), 5.51 (s, 1H),
5.40 (m, 1H), 5.15 (s, 3H), 4.90 (d, J 13.2 Hz, 1H),
4.81 (s, 2H), 4.72 (d, J 11.1 Hz, 1H), 4.58 (d, J
11.7 Hz, 1H), 4.25 (d, J 11.4 Hz, 1H), 4.14 (d, J
11.4 Hz, 1H), 4.00 (t, J 7.8 Hz, 1H), 3.85–3.67 (m,
7H), 3.57 (d, J 12.0 Hz, 1H), 3.45 (m, 1H); ESIMS
(m/z): 1306 (M+Na+). Anal. Calcd for C76H66O19: C,
71.13; H, 5.18. Found: C, 70.97; H, 5.33.
1.4. 7-O-Benzyl-3-O-(2,3,4-tri-O-benzoyl-b-D-xylopyr-
anosyl-(1!2)-3,4,6-tri-O-benzyl-b-D-glucopyranosyl)-30-
O-(2,3,4,6-tetra-O-benzoyl-b-D-glucopyranosyl)-
tamarixetin (11)
1.6. 7-O-Benzyl-3-O-(2-O-acetyl-3,4,6-tri-O-benzyl-
b-D-glucopyranosyl)-30-O-(2,3,4,6-tetra-O-benzoyl-b-D-
glucopyranosyl)tamarixetin (14)
A mixture of the 30,5-diol 9 (70 mg, 0.055 mmol), gluco-
pyranosyl bromide 10 (72 mg, 0.109 mmol), TBAB
(18 mg, 0.055 mmol), and NaOH (11 mg, 0.273 mmol)
in 1:1 CHCl3–H2O (4 mL) was stirred at 50 °C for
18 h. After neutralization with addition of 1 N HCl,
the organic layer was washed with brine, dried over
Na2SO4, and concentrated in vacuo. The residue was
purified by silica gel column chromatography (3:1 petro-
leum ether–EtOAc) to provide 11 (85 mg, 84%) as a yel-
A mixture of diol 13 (118 mg, 0.134 mmol), glucopyran-
osyl bromide 10 (177 mg, 2 equiv), TBAB (35 mg,
0.8 mmol), and NaOH (27 mg, 0.67 mmol) in 1:1
CHCl3–H2O (4 mL) was stirred at 50 °C for 12 h. After
neutralization with 1 N HCl, the organic layer was
washed with brine, dried over Na2SO4, and concen-
trated in vacuo. The residue was purified by preparative
TLC (10:1 toluene–EtOAc) to give 14 (156 mg, 80%) as
23
a yellow solid: ½aꢁD ꢀ14 (c 0.47, CHCl3); 1H NMR
23
1
low foam: ½aꢁD ꢀ58 (c 0.33, CHCl3); H NMR (CDCl3,
300 MHz): d 12.63 (s, 1H, 5-OH), 8.28–8.23 (m, 3H),
8.12–7.82 (m, 15H), 7.65–7.00 (m, 39H), 6.81 (d, J
9.0 Hz, 1H), 6.46 (d, J 2.4 Hz, 1H), 6.39 (d, J 2.4 Hz,
1H), 5.93 (d, J 7.5 Hz, 1H), 5.82 (t, J 9.3 Hz, 1H), 5.73
(d, J 8.1 Hz, 1H), 5.71–5.64 (m, 2H), 5.53 (d, J 2.1 Hz,
1H), 5.43–5.40 (m, 1H), 5.17 (d, J 3.3 Hz, 1H), 5.12 (s,
2H), 4.92 (dd, J 3.0, 13.5 Hz, 1H), 4.82 (s, 2H), 4.71–
4.67 (m, 2H), 4.61–4.53 (m, 2H), 4.43 (dd, J 5.7,
12.0 Hz, 1H), 4.18 (d, J 11.4 Hz, 1H), 4.08 (d, J
11.4 Hz, 1H), 3.98 (t, J 8.1 Hz, 1H), 3.83–3.67 (m,
5H), 3.51–3.43 (m, 2H), 3.33 (s, 3H); ESIMS (m/z):
1884 (M+Na+). Anal. Calcd for C110H92O28: C, 70.96;
H, 4.98. Found: C, 70.91; H, 5.20.
(CDCl3, 300 MHz): d 12.44 (s, 1H, 5-OH), 8.18 (dd, J
1.8, 9.0 Hz, 1H), 8.06–8.02 (m, 2H), 7.94–7.81 (m,
7H), 7.60–7.00 (m, 32H), 6.79 (d, J 9.0 Hz, 1H), 6.44
(d, J 2.1 Hz, 1H), 6.37 (d, J 2.1 Hz, 1H), 5.86 (t, J
9.0 Hz, 1H), 5.77–5.65 (m, 2H), 5.55 (d, J 8.1 Hz, 1H),
5.28 (t, J 8.7 Hz, 1H), 5.10 (s, 2H), 4.86–4.80 (m, 2H),
4.77–4.71 (m, 2H), 4.63–4.54 (m, 2H), 4.46 (dd, J 6.3,
12.3 Hz, 1H), 4.17 (d, J 11.4 Hz, 1H), 4.04 (d, J
11.4 Hz, 1H), 3.92–3.86 (m, 1H), 3.84–3.67 (m, 3H),
3.50–3.35 (m, 2H), 3.28 (s, 3H), 2.11 (s, 3H); ESIMS
(m/z): 1482 (M+Na+). Anal. Calcd for C86H74O22Æ
0.5H2O: C, 70.34; H, 5.15. Found: C, 70.32; H, 5.08.
1.7. 7-O-Benzyl-3-O-(3,4,6-tri-O-benzyl-b-D-glucopyran-
osyl)-30-O-(2,3,4,6-tetra-O-benzoyl-b-D-glucopyranosyl)-
tamarixetin (15)
1.5. 7-O-Benzyl-3-O-(2-O-acetyl-3,4,6-tri-O-benzyl-b-D-
glucopyranosyl)tamarixetin (13)
To a solution of 14 (150 mg, 0.103 mmol) in anhyd
MeOH (5 mL) and CH2Cl2 (2.5 mL) at 0 °C was added
AcCl (0.2 mL, 2.80 mmol). After stirring at rt for 20 h,
A mixture of glucopyranosyl bromide 12 (56 mg,
0.1 mmol), triol 8 (45 mg, 0.11 mmol), TBAB (32 mg,

C. Zhu et al. / Carbohydrate Research 341 (2006) 1047–1051
1051
the mixture was neutralized with Et3N and filtered. The
filtrates were concentrated to give a residue that was
purified by preparative TLC (9:1 toluene–EtOAc) to
provide 15 (45 mg, 31%) as a yellow foam (with 27 mg
(m/z): calcd for C33H40NaO21 (M+Na+): 795.1954.
Found: 795.1951.
23
1
of 14 being recovered): ½aꢁD +33 (c 0.49, CHCl3); H
NMR (CDCl3, 300 MHz): d 12.11 (s, 1H, 5-OH), 8.19
(d, J 9.0 Hz, 1H), 8.04 (d, J 8.4 Hz, 2H), 7.98–7.87 (m,
5H), 7.81 (d, J 8.4 Hz, 2H), 7.56–7.10 (m, 32H), 6.73
(d, J 9.3 Hz, 1H), 6.50 (d, J 1.8 Hz, 1H), 6.43 (d, J
1.8 Hz, 1H), 5.95 (t, J 9.6 Hz, 1H), 5.83–5.70 (m, 2H),
5.18–5.11 (m, 3H), 5.07 (d, J 7.8 Hz, 1H), 4.93–4.82
(m, 4H), 4.62–4.52 (m, 3H), 4.23–4.05 (m, 3H), 3.89 (t,
J 8.4 Hz, 1H), 3.71 (t, J 8.7 Hz, 1H), 3.64–3.56 (m,
2H), 3.49 (d, J 11.4 Hz, 1H), 3.38 (dd, J 4.5, 9.6 Hz,
1H), 3.26 (s, 3H); 13C NMR (CDCl3, 75 MHz): d
177.9, 166.0, 165.8, 165.2, 165.0, 161.5, 156.6, 153.6,
145.2, 138.9, 138.5, 138.2, 135.7, 135.4, 133.5, 133.3,
133.2, 132.8, 129.8, 129.4, 129.3, 128.7, 128.4, 128.3,
128.1, 128.0, 127.9, 127.6, 127.5, 122.3, 122.0, 111.4,
105.6, 104.9, 101.6, 99.2, 93.1, 85.2, 76.8, 76.1, 75.6,
75.1, 75.0, 73.6, 72.5, 71.7, 70.5, 69.6, 69.1, 63.1, 55.2;
HRESIMS (m/z): calcd for C84H72NaO21 (M+Na+):
1439.4458. Found: 1439.4459.
Acknowledgements
This work was supported by the Chinese Academy of
Sciences (KGCX2-SW-213-05) and the Shanghai-SK
R&D Foundation (2003013-h).
Supplementary data
Reproduction of 1H, 13C, and HMBC NMR spectra for
compound 1 are provided in Supplementary data sec-
tion. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.carres.2006.02.036.
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24
½aꢁD ꢀ112 (c 0.27, DMF); 1H NMR (DMSO-d6,
300 MHz): d 8.05 (dd, J 1.9, 8.8 Hz, 1H, H-60), 7.73
(d, J 1.9 Hz, 1H, H-20), 7.09 (d, J 9.1 Hz, 1H, H-50),
6.52 (d, J 1.9 Hz, 1H, H-8), 6.22 (s, 1H, H-6), 5.75 (d,
J 7.4 Hz, 1H, H-100), 5.74 (s, 1H, 7-OH), 5.01 (d, J
7.1 Hz, 1H, H-10000), 4.59 (d, J 7.4 Hz, 1H, H-1000), 3.87
(s, 3H, OCH3), 3.72–3.68 (m, 3H), 3.57–2.99 (m, over-
lapped with signal of H2O). 13C NMR (DMSO-d6,
100 MHz): d 177.5, 164.2, 161.0, 156.5, 155.0, 151.6,
146.2, 133.8, 124.9, 122.8, 116.0, 112.2, 104.2, 104.1,
100.9, 98.8, 98.4, 94.0, 81.4, 77.5, 77.1, 76.8, 76.7, 75.9,
73.7, 73.3, 69.8, 69.4, 65.5, 60.8, 56.1; HRESIMS