Synthesis of two bidesmosidic ursolic acid saponins bearing a 2,3-branched trisaccharide residue

Article abstract of DOI:10.1016/j.carres.2005.06.024

The focus of this work was on the synthesis of two bidesmosidic ursolic acid saponins bearing a 2,3-branched trisaccharide residue. Therefore, 3-O-{[β-d-glucopyranosyl-(1→2)]-[α-l-arabinopyranosyl-(1→3) ]-α-l-arabinopyranosyl}ursolic acid-28-O-[β-d-glucop

Full text of DOI:10.1016/j.carres.2005.06.024

Carbohydrate
RESEARCH
Carbohydrate Research 340 (2005) 2086–2096
Synthesis of two bidesmosidic ursolic acid saponins bearing a
2,3-branched trisaccharide residue
Peng Wang, Chunxia Li, Jing Zang, Ni Song, Xiuli Zhang and Yingxia Li*
Key Laboratory of Marine Drugs, Ministration of Education, Marine Drug and Food Institute, Ocean University of China,
Qingdao 266003, China
Received 1 February 2005; accepted 14 June 2005
Available online 25 July 2005
Abstract—The focus of this work was on the synthesis of two bidesmosidic ursolic acid saponins bearing a 2,3-branched trisaccha-
ride residue. Therefore, 3-O-{[b-D-glucopyranosyl-(1!2)]-[a-L-arabinopyranosyl-(1!3)]-a-L-arabinopyranosyl}ursolic acid-28-O-
[b-D-glucopyranosyl] ester 1 was concisely synthesized by two strategies in 22% and 41% overall yield, respectively, and another
congener 3-O-{[b-D-xylopyranosyl-(1!2)]-[b-D-glucopyranosyl-(1!3)]-a-L-arabinopyranosyl}ursolic acid-28-O-[b-D-glucopyrano-
1
syl] ester 2 was also efficiently prepared in 81% overall yield. The H NMR and 13C NMR signals of saponin 2 are all consistent
with those reported for the natural product.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Ursolic acid; Saponin; Glycosylation; Synthesis
1. Introduction
occurring bidesmosidic ursolic acid saponins. Saponin
1, 3-O-{[b-D-glucopyranosyl-(1!2)]-[a-L-arabinopyr-
Ursolic acid, a pentacyclic triterpene isolated from many
traditional medicinal plants, has been reported to pos-
sess a wide range of pharmacological activities, includ-
ing anti-tumor,1–3 anti-inflammatory,4 and anti-HIV.5
It is also one of the most promising chemopreventive
agents for cancer.6 Attracted by these interesting bioac-
tivities, several research groups reported on the synthesis
of the acid-based derivatives for developing more potent
compounds.7–9 Interestingly, the naturally occurring
ursolic acid saponins, the glycosidic derivatives of urso-
lic acid, are very rare. With the increasing recognition of
the importance of the saccharide part in saponin bioac-
tivities,10–12 we find ourselves more interested in how the
sugar moiety affects the bioactivities and pharmacoki-
netic properties of ursolic acid. Therefore, a project
was initiated to carry out the synthesis of ursolic acid
saponins. We were first attracted by the two naturally
anosyl-(1!3)]-a-L-arabinopyranosyl}ursolic
acid-28-
O-[b-D-glucopyranosyl] ester, was isolated from a
medicinal plant Fagonia indica.13 And another congener
saponin 2, 3-O-{[b-D-xylopyranosyl-(1!2)]-[b-D-gluco
pyranosyl-(1!3)]-a-L-arabinopyranosyl}ursolic acid-
28-O-[b-D-glucopyranosyl] ester, was isolated from
Fagonia arabica14 and Aralia decaisneana.15 The 2,3-
branched oligosaccharide chain represents a typical
structure in natural bioactive saponins16–18 and its intro-
duction to an aglycone is the crucial step to the synthe-
sis. Herein, we report the synthesis of the two saponins.
OH
''''
OH
O
R3
OH
C
O
O
OH
1
R
HO
O
O
O
R4
HO
O
'''
O
R2
OH
'
O
Saponin 1: R1= H; R2=CH2OH; R3=OH; R4=H
Saponin 2: R1= CH2OH; R2= H; R3=H; R4=OH
''
HO
HO
OH
*
Corresponding author. E-mail: liyx417@ouc.edu.cn
0008-6215/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2005.06.024

P. Wang et al. / Carbohydrate Research 340 (2005) 2086–2096
2087
2. Results and discussion
with the benzoylated arabinopyranosyl donor 321 at
ꢀ60 ꢁC, followed by deprotection of the Tr20 group by
warming the solution to room temperature for another
30 min to provide the key intermediate 5 in exclusively
the 1,2-trans glycosidic linkage. Debenzoylation with
NaOMe gave triol 6, which was subjected to DMP
(2,2-dimethoxypropane) in the presence of PPTs to af-
ford 7 in an excellent yield (91%). The simultaneous gly-
cosylation of the 20-OH and 28-CO2H groups in 7 with
the benzoylated glucopyranosyl trichloroacetimidate 821
was successfully achieved in the presence of Me3SiOTf
to give the desired 9 (80%). Removal of the acetonide
isopropylidene group afforded the 3,4-diol 10 in good
yield.
The next task was the introduction of an arabinopyr-
anosyl residue to the 30-OH of 10. It is well known that
the equatorial 30-OH is more reactive than the axial 40-
OH in many pyranosides,22,23 and so an attempt at
selective glycosylation of the 30-OH of the acceptor 10
with the acetylated arabinopyranosyl donor was made.
However, the 13C–1H HMBC spectral data showed that
glycosylation had taken place at the 40-OH. Apparently,
this unusual regioselectivity resulted from the dimin-
ished reactivity of the 30-OH due to the introduction
of the bulky benzoyled glucopyranosyl part at 20-OH.
Therefore, regioselective protection24 of the 40-OH
group in 10 with an acetyl group was first performed,
to provide the key receptor 11 in 86% yield. Next the
30-OH glycosylation with benzoylated arabinopyranosyl
donor 3 was attempted in the following process. The gly-
cosylation reaction proved difficult. After investigating a
variety of conditions, including arabinopyranosyl
donors, promoters, reaction temperature, and reaction
time, we found that compound 12 could be generated
using BF3ÆEt2O as the catalyst at ꢀ40 ꢁC for 12 h in
47% yield. When the reaction temperature was elevated
from ꢀ40 to ꢀ20 ꢁC, only a trace amount of the desired
product was obtained, meanwhile, a large amount of
acetyl migration product (acetyl group migrating from
40-OH to 30-OH in 11) was obtained.
Saponins 1 and 2 are characterized by the attachment of
a 2,3-branched trisaccharide to the C-3 position and the
glucose to the C-28 position of the ursolic acid aglycone.
It has been reported that, in convergent glycosylation
fashion, an a,b mixture was unavoidable due to the
absence of C-2 neighboring-group participation16 when
a 2,3-branched saccharide donor was incorporated with
an aglycone acceptor. In stepwise glycosylation,
however, another strategy for saponin synthesis, the
resulting saponin can be obtained stereospecifically.19
Herein, we planned to adopt the approach of stepwise
glycosylation to the target molecules. The synthetic
access to saponin 1 was first attempted as in Scheme 1.
Starting from ursolic acid, after protection of the 28-
CO2H with Tr,20 compound 4 was then glycosylated
COOH
COOTr
COOH
COOH
a
HO
HO
Ursolic acid
4
OBz
O
NH
b
c
BzO
BzO
O
3
CCl3
OBz
O
O
BzO
OBz
5
OR
RO
O
O
OH
OBz
6 R=H
7 R=C(CH3)2
d
O
BzO
BzO
BzO
NH
CCl3
e
O
8
BzO
OBz
OBz
O
C
O
O
OR1
BzO
O
O
9 R1, R2=C(CH3)2
10 R1, R2=H
R2O
OBz
O
f
g
Four anomeric proton signals at d 4.27 (J 7.3 Hz,
H-10), 4.54 (J 6.4 Hz, H-1000), 4.71 (J 7.3 Hz, H-100), 5.88
(J 8.7 Hz, H-10000) and carbon signals at d 104.1 (C-10),
O
11 R1=Ac, R2=H
OBz
BzO
BzO
h
1
100.4 (C-100, C-1000), 92.0 (C-10000) in the H NMR and
BzO
OBz
13C NMR spectra of 12 indicated a b-linkage to the
glucopyranosyl residue and an a-linkage to the arabino-
pyranosyl residue. The HMBC cross peaks between H-100
(glucose)!C-20 (inner arabinose) and H-1000 (terminal
arabinose)!C-30 (inner arabinose) prove the intergly-
cosidic linkage of glucose at position C-20 and terminal
arabinose at position C-30 of the inner arabinose. The
target saponin 1 was finally obtained by removal of all
the protective groups with NaOMe in 22% overall yield.
The low yield was attributed to the difficulty of glycosyl-
ation of the highly hindered 30-OH in acceptor 11 at the
later stage. To our surprise, we found that the 1H NMR
O
OBz
C
O
O
BzO
OAc
O
OBz
O
O
O
BzO
OBz
O
12
OBzO
OBz
c
BzO
BzO
Saponin 1
Scheme 1. Reagents and conditions: (a) TrCl, DBU, reflux, 82%; (b) 3,
Me3SiOTf (0.3 equiv), ꢀ60 ꢁC!rt; (c) CH3ONa, rt, 96% for 6 two
steps; 99% for 1; (d) PPTs, (CH3)2C(OCH3)2, rt, 12 h, 91%; (e) 8,
Me3SiOTf (0.1 equiv), 0 ꢁC!rt, 80%; (f) 80% AcOH, 70 ꢁC, 94%; (g)
(i) p-TsOHÆH2O, CH3C(OCH2CH3)3, rt, (ii) 50%AcOH, 70 ꢁC, 86%;
(h) BF3ÆEt2O, ꢀ40 ꢁC!rt, 47%.

2088
P. Wang et al. / Carbohydrate Research 340 (2005) 2086–2096
and 13C NMR signals of saponin 1 are not consistent
with those in the literature.13
OR1
OR
a
c
O
O
L
-Arabinose
R2O
LevO
RO
HO
13 R=H
To further prove the structure of saponin 1 and im-
prove the overall yield, we intended to adopt an alterna-
tive process to synthesize saponin 1 and its congener
saponin 2, that is, the (1!3)-disaccharide residue was
the first to be coupled with the 30-OH of ursolic acid ste-
reoselectively, and then another monosaccharide was to
be introduced to the 20-OH. Such a strategy could
ensure the stereoselective formation of the desired 1,2-
trans 3-O-glycosidic linkages in the aglycone and also
avoid the difficulty in the glycosylation of 30-OH in the
inner arabinose residue. The corresponding retrosyn-
thetic analysis is shown in Scheme 2, and the synthetic
route to saponin 1 and 2 is described in Scheme 3.
The key monosaccharide 17 was prepared from L-
arabinose in five steps. L-Arabinose was first treated
with BnOH and BF3ÆEt2O to give benzyl b-L-arabino-
pyranoside (13), which was isopropylidenated to provide
14 with the 20-OH free. To obtain a distinguishable 2-O-
protecting group, allowing selective cleavage in the
presence of an acyl protecting group and ensuring the
stereoselectivity in forming the 1,2-trans glycosidic link-
ages, herein, the Lev25 group was chosen and introduced
by the treatment of 14 with levulinic acid, DCC-DMAP
to obtain 15 in quantitative yield. Then the removal of
the isopropylidene group from 15 with 80% AcOH read-
ily produced the 3,4-diol 16 in 93% yield, which was
acetylated regioselectively at 4-OH by using the same
procedure as for 10, providing acceptor 17 with 30-OH
free in 94% yield.
The (1!3)-b-disaccharides 18 and 19 were obtained
by glycosylation of 17 with benzoylated glucopyranosyl
donor 8 and benzoylated arabinopyranosyl donor 3,
respectively, under standard conditions in good yield.
The anomeric benzyl groups of 18 and 19 were hydro-
genolyzed under Pd–C (10%) for 12 h to afford hemiace-
tals 20 and 21, which were then converted into the
corresponding trichloroacetimidate donors 22 and 23.
The receptor 24 was first prepared in 99% yield by
selective glycosylation of the 28-CO2H group in the
ursolic acid aglycone with 2,3,4,6-tetra-O-acetyl-a-D-
glucopyranosyl bromide26 under phase-transfer condi-
OBn
OBn
15 R1,R2=C(CH3)2
d
e
b
16 R1,R2=H
14 R=C(CH3)2
17 R1=Ac, R2=H
OAc
OAc
OAc
O
O
O
g
h
OH
NH
RO
RO
RO
LevO
OLev
O
CCl3
LevO
f
OBn
22, 23
20, 21
17 R=H
18, 19
AcO
OAc
OAc
O
O
OAc
O
AcO
i
C
O
AcO
AcO
Ursolic acid
HO
AcO
Br
24
OBz
OAc
O
BzO
BzO
O
O
NH
OBz
LevO
O
CCl3
22
j
OBz
OAc
O
O
O
NH
BzO
OBz
LevO
O
CCl3
AcO
OAc
OAc
23
O
O
AcO
C
OAc
O
O
O
RO
OR1
25, 26 R1=Lev
27, 28 R1=H
29, 30
k
l
O
AcO
AcO
AcO
NH
m
O
CCl3
31
OAc
O
AcO
AcO
AcO
NH
1 or 2
O
CCl3
32
OBz
O
O
AcO
30 R1=
29 R1=
BzO
18, 20, 22, 26, 28, 30 R=
19, 21, 23, 25, 27, 29 R=
AcO
BzO
OBz
OAc
OBz
OAc
O
O
AcO
AcO
BzO
OAc
OBz
Scheme 3. Reagents and conditions: (a) BnOH, BF3ÆEt2O, 95 ꢁC, 46%;
(b) DMP, p-TsOHÆH2O, rt, 12 h, 79%; (c) DCC, DMAP, rt, 12 h,
quant.; (d) 70% AcOH, 70 ꢁC, 93%; (e) (i) CH3C(OCH2CH3)3, p-
TsOHÆH2O, rt, 12 h; (ii) 80% AcOH, 70 ꢁC, 94%; (f) Me3SiOTf
(0.1 equiv), CH2Cl2, ꢀ20 ꢁC, 79% for 18, 88% for 19; (g) Pd–C (10%),
rt, 81% for 20, 88% for 21; (h) CCl3CN, DBU, rt, 71% for 22, 57% for
23; (i) Bu4NBr, CH2Cl2–H2O, K2CO3, 99%; (j) 22 or 23, Me3SiOTf
(0.2 equiv), CH2Cl2, ꢀ20 ꢁC, 88% for 25, 96% for 26; (k) NH2NH2–
HOAc, CH2Cl2–CH3OH, 91% for 27, 90% for 28; (l) Me3SiOTf
(0.1 equiv), ꢀ40 ꢁC, 12 h, 53% for 29, 97% for 30; (m) NaOMe–
MeOH, 98% for 1, 98% for 2.
AcO
OAc
O
OAc
O
Glycosyl donor
Saponin 1, 2
C
O
AcO
OAc
O
O
O
O
BzO
OLev
AcO
OAc
OAc
OAc
OAc
O
O
O
O
O
NH
O
LevO
C
O
Ursolic acid
AcO
AcO
AcO
BzO
AcO
O
CCl3
Br
HO
Scheme 2. Retrosynthetic analysis of saponins 1 and 2.

P. Wang et al. / Carbohydrate Research 340 (2005) 2086–2096
2089
tions. Then coupling 24 with donors 22 and 23, respec-
tively, in the presence of Me3SiOTf was performed to
provide the expected products 25 and 26 in good yield
and uniquely a-linked. Removal of the Lev group of
25 and 26 with NH2NH2–HOAc generated acceptors
27 and 28 with a free 20-OH.
nal standard, and chemical shifts are recorded in d val-
ues. Mass spectra were recorded on a Q-TOF Global
mass spectrometer.
3.2. Trityl ursolic ester (4)
For introducing another sugar residue to the 20-OH,
the acceptor 27 was first glycosylated with benzoylated
glucopyranosyl trichloroacetimidate 8 under standard
conditions, however, this led to no reaction. This prob-
lem is probably due to the fact that 20-OH of the arabi-
nopyranosyl residue was surrounded by the rigid
triterpene ring and the bulky benzoylated arabinopyr-
anosyl part, and the high steric hindrance further
decreased the reactivity of 20-OH. On the basis of this
above analysis, the donor was changed to the smaller
acetylated glucopyranosyl trichloroacetimidate 32.27
And the coupling of the hindered 20-OH of 27 with the
acetylated glucopyranosyl donor under ꢀinverse additionꢁ
conditions28 was then performed to give a satisfactory
yield of the desired compound 29 (53%). Glycosylation
of 28 with the acetylated xylopyranosyl trichloroacetim-
idate29 under the same conditions gave 30 in excellent
(97%) yield. The striking difference between the glycosyl-
ation yields is due to that the larger six-carbon glucopyr-
anose has more difficultly accessing the 20-OH compared
with that of the five-carbon xylopyranose or the 6-deox-
genated six-carbon rhamnopyranose.17 Deprotection of
29 with NaOMe gave the target saponin 1, once again
in 41% overall yield (better than 22%) and with exactly
the same spectral data as those of the product synthe-
sized above, indicating that the structure of the synthetic
saponin 1 is correct. More significantly, the deprotection
To a suspension of ursolic acid (0.611 g, 1.34 mmol) in
THF (15 mL) were added DBU (0.32 mL, 2.14 mmol)
and TrCl (0.517 g, 1.85 mmol). The mixture was stirred
at reflux for 16 h. Removal of solvent afforded a residue
that was subjected to column chromatography (5:1
petroleum ether–EtOAc) to give 4 as a yellow solid
(0.766 g, 82%): Rf 0.50 (3:1 petroleum ether–EtOAc);
1H NMR (CDCl3): d 7.20–7.40 (m, 15H, Ph · 3), 5.21
(t, J 3.3 Hz, 1H, H-12), 3.19–3.21 (m, 1H, H-3), 2.23
(d, J 11.4 Hz, 1H, H-18), 2.04 (td, J 13.6, 4.7 Hz, 1H),
1.05, 0.97, 0.88, 0.78, 0.36 (s each, 3H each, Me · 5),
0.94 (d, J 6.2 Hz, 3H), 0.83 (d, J 6.6 Hz, 3H), 0.67 (d,
J 11.0 Hz, 1H, H-5).
3.3. Ursolic acid-3-yl a-L-arabinopyranoside (6)
To a mixture of compound 4 (1.06 g, 1.52 mmol), 3
˚
(1.20 g, 1.98 mmol), and powdered 4 A molecular sieves
in dried CH2Cl2 (10 mL) at ꢀ60 ꢁC was added Me3-
SiOTf (53 lL, 0.15 mmol). After stirring at ꢀ60 ꢁC for
0.5 h and at rt for 0.5 h, the reaction was quenched with
Et3N. The solid was then filtered off. The filtrate was
concentrated under vacuum to give a yellow oil, which
was purified by column chromatography (4:1 petroleum
ether–EtOAc) to give compound 5 as a crude. Com-
pound 5 was dissolved in MeOH–CH2Cl2 (2:1, 21 mL),
and then NaOMe (100 mg, 50%) was added. After stir-
ring at rt for 4 h, the solution was neutralized with
ion-exchange resin (H+), filtered, and concentrated.
The residue was purified by column chromatography
(20:1!2:1 CHCl3–MeOH) to afford 6 as a white solid
1
of 30 gave the target 2 in 81% overall yield, and its H
NMR and 13C NMR signals are all consistent with those
reported for the natural product.14,15
In conclusion, a concise and effective procedure has
been successfully developed for the synthesis of bides-
mosidic ursolic acid saponins bearing a 2,3-branched
oligosaccharide moieties. The result of the present inves-
tigation should be of value in the synthesis of structural
analogs.
20
(0.86 g, 96%): Rf 0.50 (10:1 CHCl3–MeOH); ½aꢁD
1
+43.5 (c 0.17, CHCl3); H NMR (CD3OD): d 5.21 (t,
J 3.7 Hz, 1H, H-12), 4.26 (d, J 6.9 Hz, 1H, H-10),
3.79–3.83 (m, 2H), 3.49–3.57 (m, 3H), 3.13 (dd, J 11.4,
4.1 Hz, 1H, H-3), 2.19 (d, J 11.4 Hz, 1H, H-18), 1.11,
1.01, 0.96, 0.84, 0.84 (s each, 3H each, Me · 5), 0.87
(d, J 6.8 Hz, 3H), 0.78 (d, J 11.5 Hz, 1H, H-5); 13C
NMR (CDOD3): d 175.0 (C-28), 139.6 (C-13), 126.9
(C-12), 107.1 (C-10), 90.7 (C-3), 74.3, 72.8, 69.5, 66.4,
57.0, 54.4, 48.0, 42.2, 40.8, 40.4 (·2), 40.2, 39.9, 38.1,
37.8, 34.3, 31.8, 29.2, 28.6, 27.0, 25.3, 24.4, 24.1, 21.6,
19.3, 17.8, 17.7, 17.0, 16.1; ESI-MS (m/z): 611.0
[M+Na]+ (Calcd 611.0).
3. Experimental
3.1. General methods
Solvents were purified conventionally. Thin-layer chro-
matography (TLC) was performed on precoated Merck
silica gel 60 F254 plates. Flash column chromatography
was performed on silica gel (200–300 mesh, Qingdao,
China). Optical rotations were determined with a Per-
3.4. Ursolic acid-3-yl 3,4-O-isopropylidine-a-L-arabino-
pyranoside (7)
1
kin–Elmer Model 241 MC polarimeter. H NMR and
13C NMR spectra were taken on a Jeol JNM-ECP 600
spectrometer with tetramethylsilane (Me4Si) as the inter-
To a solution of 6 (0.37 g, 0.63 mmol) and 2,2-dimeth-
oxypropane (0.78 mL, 6.33 mmol) in dried DMF

2090
P. Wang et al. / Carbohydrate Research 340 (2005) 2086–2096
(10 mL) was added TsOH (50 mg). After stirring at rt
for 24 h, the mixture was neutralized with Et3N and con-
centrated under vacuum. The residue was purified by sil-
ica gel column chromatography (2:1 petroleum ether–
EtOAc) to give 7 as a white solid (0.37 g, 94%): Rf
trated in vacuum. The residue was directly purified by
silica gel column chromatography (2:1!1:1 petroleum
ether–EtOAc) to afford 10 (0.430 g, 94%) as a white
20
solid: Rf 0.27 (1:1 petroleum ether–EtOAc); ½aꢁD +37.6 (c
1
0.12, CHCl3); H NMR (CDCl3): d 7.26–8.03 (m, 40H,
20
0.30 (10:1 CHCl3–MeOH); ½aꢁD +57.6 (c 0.17, CHCl3);
Ph · 8), 5.97 (t, J 10.1 Hz, 1H, H-3000), 5.90 (dd, J 9.7,
12.8 Hz, 1H, H-300), 5.88 (d, J 8.3 Hz, 1H, H-1000),
5.67–5.75 (m, 3H, H-2000, H-4000, H-400), 5.53 (dd, J 8.2,
9.6 Hz, 1H, H-200), 5.22 (t, J 3.2 Hz, 1H, H-12), 5.11
(d, J 7.8 Hz, 1H, H-100), 4.75 (d, J 2.8 Hz, 1H, H-10),
4.59 (dd, J 3.2, 12.4 Hz, 1H, H-600-1). 4.53 (dd, J 2.8,
9.1 Hz, 1H, H-6000-1), 4.45–4.49 (m, 2H, H-600-2, H-6000-
2), 4.23–4.26 (m, 1H, H-5000), 4.16–4.19 (m, 1H, H-500),
3.96 (t, J 3.7 Hz, 1H, H-20), 3.68–3.72 (m, 2H, H-30,
H-40), 3.63 (dd, J 8.7, 11.5 Hz, 1H, H-50-1), 3.49 (dd, J
4.4, 11.5 Hz, 1H, H-50-2), 3.02 (dd, J 4.6, 11.9 Hz, 1H,
H-3), 2.95 (s, 1H, OH), 2.88 (s, 1H, OH), 2.13 (d, J
11.0 Hz, 1H, H-18), 0.89, 0.84, 0.73, 0.70, 0.44 (s each,
3H each, Me · 3), 0.82 (d, J 6.4 Hz, 3H), 0.48 (d, J
11.5 Hz, 1H, H-5); 13C NMR (CDCl3): d 174.4 (C-28),
165.1, 165.0, 164.7, 164.6, 164.1 (·2), 163.7, 161.5,
136.3 (C-13), 127.3–132.5 (Ph–C), 126.6 (C-12), 100.5
(C-10), 100.3 (C-100), 90.9 (C-1000), 88.9 (C-3), 76.0, 71.8,
71.7, 71.3, 70.9, 69.3, 69.1, 68.4, 68.2, 63.7, 62.0, 61.7,
54.0 (C-5), 51.4 (C-18), 47.1, 46.2, 40.8, 38.0, 37.9,
37.8, 37.7, 37.3, 35.4, 34.9, 30.9, 29.6, 29.4, 28.7, 26.9,
24.5, 22.8, 22.1, 20.1, 17.0, 16.0, 15.4, 14.3.
1H NMR (CDCl3): d 11.25 (br s, 1H, –COOH), 5.23
(t, J 3.3 Hz, 1H, H-12), 4.21 (d, J 7.7 Hz, 1H, H-10),
4.18–4.20 (m, 2H, H-40, H-50-1), 4.06 (dd, J 7.7,
5.9 Hz, 1H, H-30), 3.76 (dd, J 13.9, 3.7 Hz, 1H, H-50-
2), 3.63 (t, J 7.7 Hz, 1H, H-20), 3.12 (dd, J 4.4,
11.7 Hz, 1H, H-3), 2.18 (d, J 11.3 Hz, 1H, H-18), 1.54,
1.36 (s each, 3H each, Me2C), 1.06, 0.99, 0.93, 0.81,
0.76 (s each, 3H each, Me · 5), 0.93 (d, J 8.0 Hz,
1H, H-30), 0.85 (d, J 6.6 Hz, 3H, H-29), 0.73 (d, J
11.3 Hz, 1H, H-5); ESI-MS (m/z): 651.1 [M+Na]+
(Calcd 651.4).
3.5. 3-O-[2,3,4,6-Tetra-O-benzoyl-b-D-glucopyranosyl-
(1!2)-3,4-O-isopropylidine-a-L-arabinopyranosyl]ursolic
acid-28-O-[2,3,4,6-tetra-O-benzoyl-b-D-glucopyranosyl]
ester (9)
To a mixture of compound 7 (0.208 g, 0.33 mmol), 8
˚
(0.736 g, 0.99 mmol), and powdered 4 A molecular
sieves in dried CH2Cl2 (10 mL) at 0 ꢁC was added Me3-
SiOTf (7.4 lL, 0.033 mmol). After the mixture was stir-
red at 0 ꢁC for 1 h, the reaction was quenched with
Et3N. The solid was filtered off and the filtrate was then
concentrated in vacuum. The resulting residue was puri-
fied by column chromatography (1:30 EtOAc–CHCl3)
to give compound 9 as a yellow solid (0.47 g, 80%); Rf
3.7. 3-O-[2,3,4,6-Tetra-O-benzoyl-b-D-glucopyranosyl-
(1!2)-4-O-acetyl-a-L-arabinopyranosyl]ursolic acid-28-
O-[2,3,4,6-tetra-O-benzoyl-b-D-glucopyranosyl] ester (11)
1
0.30 (1:20 EtOAc–CHCl3); H NMR (CDCl3): d 7.26–
Triethyl orthoacetate (0.48 mL, 2.4 mmol) and p-TsOHÆ
H2O (20 mg) were added to the solution of 10
(0.43 g, 0.24 mmol) in CH2Cl2 (10 mL). After the reac-
tion mixture was stirred at rt overnight, 50% AcOH
(10 mL) was added. The solution was vigorously stirred
for 30 min, diluted with CH2Cl2 (100 mL), and succes-
sively washed with water (30 mL · 2), satd aq NaHCO3
(30 mL · 2), and brine (30 mL · 2). The organic layer
was dried over anhydrous Na2SO4 and then concen-
trated under vacuo. The residue was purified by silica
gel column chromatography (2:1 petroleum ether–
EtOAc) to give 11 (0.38 g, 86%) as a white solid: Rf
8.06 (m, 40H, Ph · 8), 5.98 (t, J 9.5 Hz, 1H, H-3000),
5.91 (t, J 9.9 Hz, 1H, H-300), 5.88 (d, J 8.0 Hz, 1H, H-
1000), 5.68–5.75 (m, 3H, H-2000, H-4000, H-400), 5.50 (dd, J
8.0, 9.5 Hz, 1H, H-200), 5.32 (d, J 8.1 Hz, 1H, H-100),
5.21 (t, J 3.3 Hz, 1H, H-12), 4.60 (dd, J 3.3, 12.1 Hz,
1H, H-600-1), 4.54 (dd, J 2.9, 12.4 Hz, 1H, H-6000-1),
4.50 (dd, J 4.7, 14.6 Hz, 1H, H-600-2), 4.46 (dd, J 4.7,
12.1 Hz, 1H, H-6000-2), 4.33 (d, J 6.6 Hz, 1H, H-10),
4.23–4.26 (m, 1H, H-5000), 4.10–4.15 (m, 2H, H-40, H-
500), 3.87–3.94 (m, 3H, H-20, H-30, H-50-1), 3.67 (dd, J
4.4, 12.8 Hz, 1H, H-50-2), 2.94 (dd, J 4.4, 11.3 Hz, 1H,
H-3), 2.12 (d, J 11.4 Hz, 1H, H-18), 1.49, 1.25 (s each,
3H each, –CMe2), 0.96, 0.90, 0.87, 0 86, 0.40 (s
each, 3H each, Me · 5), 0.81 (d, J 6.6 Hz, 3H, H-30),
0.70 (d, J 5.8 Hz, 3H, H-29), 0.49 (d, J 11.8 Hz, 1H,
H-5).
20
0.38 (1:1 petroleum ether–EtOAc); ½aꢁD +43.5 (c 0.17,
CHCl3); 1H NMR (CDCl3): d 7.26–7.98 (m, 40H,
Ph · 8), 5.98 (t, J 9.6 Hz, 1H, H-3000), 5.88–5.91 (m,
2H, H-1000, H-300), 5.71–5.76 (m, 3H, H-2000, H-4000, H-
400), 5.54 (dd, J 8.3, 10.1 Hz, 1H, H-200), 5.23 (t, J
3.2 Hz, 1H, H-12), 5.20 (d, J 7.8 Hz, 1H, H-100), 4.86–
4.88 (m, 1H, H-40), 4.60–4.62 (m, 2H, H-10, H-600-1),
4.45–4.56 (m, 3H, H-600-2, H-6000-1, H-6000-2), 4.23–4.26
(m, 1H, H-5000), 4.16–4.19 (m, 1H, H-500), 3.94 (dd, J
5.9, 4.6 Hz, 1H, H-20), 3.84–3.87 (m, 2H, H-30, H-50-
1), 3.50 (dd, J 11.9, 3.2 Hz, 1H, H-50-2), 3.02 (dd, J
4.6, 11.4 Hz, 1H, H-3), 2.14 (d, J 11.5 Hz, 1H, H-18),
3.6. 3-O-[2,3,4,6-Tetra-O-benzoyl-b-D-glucopyranosyl-
(1!2)-a-L-arabinopyranosyl]ursolic acid-28-O-[2,3,4,6-
tetra-O-benzoyl-b-D-glucopyranosyl] ester (10)
A solution of 9 (0.470 g, 0.26 mmol) in 80% AcOH
(15 mL) was stirred at 70 ꢁC for 12 h and then concen-

P. Wang et al. / Carbohydrate Research 340 (2005) 2086–2096
2091
1.96 (s, 3H, Ac), 0.91, 0.89, 0.73, 0.73, 0.43 (s each, 3H
3.9. Benzyl 2-O-levulinyl-3,4-O-isopropylidene-b-L-
arabinopyranoside (15)
each, Me · 5), 0.81 (d, J 6.4 Hz, 3H, H-29), 0.50 (d, J
11.4 Hz, 1H, H-5); 13C NMR (CDCl3): d 175.5 (C-28),
170.3, 166.2, 166.1, 165.8, 165.7, 165.2, 165.1 (·2),
164.8, 137.3 (C-13), 128.3–133.5 (Ph–C), 125.9 (C-12),
102.5 (C-10), 101.2 (C-100), 92.0 (C-1000), 90.2 (C-3), 77.4
(C-20), 72.8 (C-300, C-3000, C-5000), 72.2 (C-200, C-500), 70.4
(C-2000), 69.8 (C-30), 69.6 (C-400), 69.2 (C-4000), 68.9 (C-
40), 63.1 (C-600), 62.7 (C-6000), 59.3 (C-50), 55.2 (C-5),
52.5 (C-18), 48.1, 47.3, 41.8, 39.0, 38.9, 38.8, 38.4,
36.4, 35.9, 32.0, 30.5, 29.7, 28.2, 27.9, 25.7, 23.9, 23.2,
23.1, 21.1, 20.9, 18.0, 17.0, 16.4, 15.3.
BF3ÆEt2O (0.75 mL) was added to the suspension of
L-arabinose (5.0 g, 33.3 mmol) in BnOH (40 mL). The
mixture was stirred at 90–100 ꢁC for 2.5 h and the reac-
tion was quenched with Et3N. The mixture was poured
into dry ether (250 mL), kept at 4 ꢁC for 4 h, and then
recrystallized from ether to give 13 (3.68 g, 46%). A solu-
tion of 13 (1.60 g, 6.66 mmol), 2,2-dimethoxypropane
(1.65 mL, 13.32 mmol) and p-TsOHÆH2O (50 mg) in
dried DMF (10 mL) was stirred at rt for 12 h. The mix-
ture was neutralized with Et3N, concentrated in vacuo
and redissolved in EtOAc (100 mL). The solution was
then washed with satd aq NaHCO3 (30 mL · 2) and
brine (30 mL · 2) successively. The organic layer was
dried (Na2SO4) and concentrated to give a residue,
which was purified by silica gel column chromatography
(3:1 petroleum ether–EtOAc) to give 14 (0.74 g, 79%).
To a solution of 14 (1.2 g, 4.28 mmol) in dried CH2Cl2
(15 mL) were added DCC (1.6 g, 7.70 mmol), DMAP
(50 mg), and levulinic acid (1.5 g, 12.84 mmol). After
stirring at rt for 12 h, the mixture was filtered and con-
centrated. The residue was purified by column chroma-
tography (4:1 petroleum ether–EtOAc) to give 15
(1.62 g, 100%) as a white solid: Rf 0.50 (1:1 petroleum
3.8. 3-O-{[2,3,4,6-Tetra-O-benzoyl-b-D-glucopyranosyl-
(1!2)]-[2,3,4-tri-O-benzoyl-a-L-arabinopyranosyl-
(1!3)]-4-O-acetyl-a-L-arabinopyranosyl}ursolic acid-28-
O-[2,3,4,6-tetra-O-benzoyl-b-D-glucopyranosyl] ester (12)
To a mixture of compound 11 (0.12 g, 0.067 mmol),
benzoylated arabinopyranosyl donor 3 (0.16 g, 0.268
˚
mmol), and powdered 4 A molecular sieves in
dried CH2Cl2 (5 mL) at ꢀ40 ꢁC was added BF3ÆOEt2
(8.5 lL, 0.067 mmol). The mixture was stirred at
ꢀ40 ꢁC for 12 h and the reaction was quenched with
Et3N. The solid was then filtered off and the filtrate con-
centrated in vacuo to give a yellow syrup, which was
purified by column chromatography (4:1!2:1 petro-
leum ether–EtOAc) to give compound 12 as a white
foam (0.07 g, 47%): Rf 0.17 (2:1 petroleum ether–
1
ether–EtOAc); H NMR (CDCl3): d 7.26–7.33 (m, 5H,
Ph), 5.00 (d, J 3.3 Hz, 1H, H-1), 4.92 (dd, J 8.0,
3.3 Hz, 1H, H-2), 4.72 (d, J 12.1 Hz, 1H, Ph–CH2),
4.52 (d, J 12.1 Hz, 1H, Ph–CH2–), 4.37 (dd, J 8.1,
5.5 Hz, 1H, H-3), 4.25–4.26 (dt, J 5.5, 1.8 Hz, 1H, H-
4), 4.01–4.02 (m, 2H, H-5), 2.63–2.77 (m, 4H, Lev),
2.16 (s, 3H, Lev), 1.54, 1.36 (s each, 3H each, Me · 2).
20
EtOAc); ½aꢁD +108.8 (c 0.17, CHCl3); 1H NMR
(CDCl3): d 7.26–8.27 (m, 55H, Ph · 11), 6.00 (t, J
9.6 Hz, 1H, H-30000), 5.88 (d, J 8.7 Hz, 1H, H-10000),
5.64–5.76 (m, 4H, H-20000, H-300, H-40000, H-2000), 5.40–
5.47 (m, H-400, H-3000, H-200), 5.35 (br s, 1H, H-4000),
5.21–5.22 (m, 2H, H-40, H-12), 4.71 (d, J 7.3 Hz, 1H,
H-100), 4.53–4.56 (m, 2H, H-1000, H-60000-1), 4.48 (dd, J
11.9, 4.6 Hz, 1H, H-60000-2), 4.36 (dd, J 11.9, 3.7 Hz,
1H, H-600-1), 4.24–4.28 (m, 2H, H-10, H-50000), 4.19 (dd,
J 11.9, 5.0 Hz, 1H, H-600-2), 3.80–3.92 (m, 4H, H-20,
H-30, H-50-1, H-5000-1), 3.45 (d, J 12.4 Hz, 1H, H-50-2),
2.99 (dd, J 11.5, 4.1 Hz, 1H, H-3), 2.59 (m, 1H, H-500),
2.40 (d, J 11.5 Hz, 1H, H-5000-2), 2.22 (s, 3H, CH3CO),
2.13 (d, J 11.5 Hz, 1H, H-18), 1.90 (td, J 9.7, 4.1 Hz,
1H, H-16-1), 1.77–1.79 (m, 3H), 1.10, 0.89, 0.69, 0.65,
0.41 (s each, 3H each, CH3 · 5), 0.82 (d, J 6.4 Hz,
3H), 0.51 (d, J 13.3 Hz, 1H, H-5); 13C NMR (CDCl3):
d 175.4 (C-28), 170.5 (MeCO), 166.1, 165.9 (·2), 165.7
(·2), 165.6, 165.2, 165.1, 164.8, 164.7 (·2), 137.3 (C-
13), 128.2–133.9 (Ph–C), 125.9 (C-12), 104.1 (C-10),
100.4 (C-100, C-1000), 92.0 (C-10000), 90.4 (C-3), 76.6 (C-
30), 75.7 (C-20), 69.3-72.8 (C-40, C-200, C-300, C-400, C-500,
C-2000, C-3000, C-20000, C-30000, C-40000, C-50000), 68.2 (C-4000),
63.8 (C-50), 63.4 (C-5000), 63.1 (C-600), 62.7 (C-60000), 55.5
(C-5), 52.5 (C-18), 48.1, 47.3, 41.8, 39.2, 39.0 (2 C),
38.7, 36.4, 35.9, 31.9, 30.5, 29.7, 28.3, 27.7, 25.8, 23.9,
23.2, 23.0, 22.7, 21.1, 18.0, 17.0, 16.4, 15.3.
3.10. Benzyl 2-O-levulinyl-4-O-acetyl-b-L-arabino-
pyranoside (17)
A suspension of 15 (1.62 g, 4.28 mmol) in 70% AcOH
(30 mL) was stirred at 70 ꢁC for 1 h and then concen-
trated and redissolved in CH2Cl2 (100 mL). The organic
layer was successively washed with satd aq NaHCO3
(30 mL · 2), and brine (30 mL · 2), dried over anhy-
drous Na2SO4, and then concentrated in vacuo. The res-
idue was purified by column chromatography (50:1
CHCl3–MeOH) to give a white solid 16 (1.34 g, 93%).
A solution of 16 (1.34 g, 4.00 mmol), triethyl orthoace-
tate (2.02 mL, 10.0 mmol) and p-TsOHÆH2O (40 mg) in
CH2Cl2 (25 mL) was stirred at rt for 1.5 h, 80% AcOH
(10 mL) was added, and the mixture was vigorously stir-
red for another 30 min and then diluted with CH2Cl2
(70 mL). The solution was successively washed with
water (30 mL · 2), satd aq NaHCO3 (30 mL · 2), and
brine (30 mL · 2), dried over anhydrous Na2SO4, and
concentrated in vacuo. The resulting residue was puri-
fied by silica gel column chromatography (2:1 petroleum
ether–EtOAc) to give 17 as a white solid (1.74 g, 94%):

2092
P. Wang et al. / Carbohydrate Research 340 (2005) 2086–2096
20
Rf 0.20 (1:2 petroleum ether–EtOAc); ½aꢁD +194.7 (c
H-60-1), 4.48 (dd, J 4.7, 12.1 Hz, 1H, H-60-2), 4.43 (d,
J 12.1 Hz, 1H, Ph–CH2–), 4.21 (dd, J 3.7, 10.3 Hz,
1H, H-3), 4.14–4.22 (m, 1H, H-50), 3.77 (d, J 13.2 Hz,
1H, H-5-1), 3.66 (dd, J 2.2, 13.2 Hz, 1H, H-5-2), 1.84–
2.39 (m, 4H, Lev), 2.08, 2.05 (s each, 3H each,
2 · CH3CO–); 13C NMR (CDCl3): d 205.9, 171.7,
170.4, 166.0, 165.8, 165.1, 164.7, 128.0–137.0 (Ph–C),
101.6 (C-10), 95.6 (C-1), 76.8, 73.7, 72.8, 72.0, 70.8,
70.0 (2C), 69.4, 62.8, 60.4, 37.6, 29.7, 27.2, 21.0.
1
0.17, CHCl3); H NMR (CDCl3): d 7.26–7.36 (m, 5H,
Ph), 5.17–5.18 (m, 1H, H-4), 5.06–5.10 (m, 2H, H-1,
H-3), 4.73 (d, J 11.9 Hz, 1H, PhCH2–), 4.53 (d, J
11.9 Hz, 1H, PhCH2–), 4.26 (dd, J 3.7, 9.6 Hz, 1H, H-
2), 3.92 (dd, J 0.9, 13.3 Hz, 1H, H-5-1), 3.77 (dd, J
1.9, 12.8 Hz, 1H, H-5-2), 2.58–2.77 (m, 4H, Lev), 2.17,
2.16 (s each, 3H each, CH3CO); ESI-MS (m/z): 402.8
[M+Na]+ (Calcd 403.1).
3.13. 2-O-Levulinyl-3-O-(2,3,4-tri-O-benzoyl-a-L-arabino-
pyranosyl)-4-O-acetyl-b-L-arabinopyranosyl trichloroace-
timidate (23)
3.11. Benzyl 2-O-levulinyl-3-O-(2,3,4-tri-O-benzoyl-a-L-
arabinopyranosyl)-4-O-acetyl-a-L-arabinopyranoside (19)
To a solution of compound 17 (0.30 g, 0.79 mmol), ben-
zoylated arabinopyranosyl donor 3 (0.72 g, 1.18 mmol),
and powdered 4 A molecular sieves in dried CH2Cl2
A suspension of 19 (0.563 g, 0.682 mmol) and 10% Pd–C
(0.2 g) in MeOH–CH2Cl2 (1:1, 12 mL) was stirred under
H2 atmosphere at rt for 14 h and then filtered. The fil-
trate was concentrated in vacuo to give a yellow syrup,
which was purified by flash column chromatography
(2:1 petroleum ether–EtOAc) to give 21 (0.440 g, 88%)
˚
(10 mL) was added Me3SiOTf (13.7 lL, 0.079 mmol).
The mixture was stirred at ꢀ20 ꢁC for 1 h, and the reac-
tion was quenched with Et3N. The solid was then fil-
tered off and the filtrate concentrated under vacuum to
give a yellow oil, which was purified by column chroma-
tography (2:1 petroleum ether–EtOAc) to give com-
pound 19 (0.57 g, 88%) as a white solid: Rf 0.35 (1:1
as
a white foam. The solution of 21 (0.440 g,
0.60 mmol), CCl3CN (0.48 mL, 4.8 mmol), and DBU
(44.8 lL, 0.3 mmol) in CH2Cl2 was stirred at rt for
2 h, then concentrated in vacuo. The resulting residue
was purified by flash column chromatography (3:1
petroleum ether–EtOAc) to give 23 (0.30 g, 57%) as a
white foam; Rf 0.50 (1:1 petroleum ether–EtOAc).
20
petroleum ether–EtOAc); ½aꢁD +194.3 (c 0.17, CHCl3);
1H NMR (CDCl3): d 7.30–8.03 (m, 20H, Ph · 4), 5.66–
5.68 (m, 1H, H-40), 5.61–5.63 (m, 2H, H-20, H-30), 5.34
(m, 1H, H-4), 5.16 (dd, J 3.3, 10.3 Hz, 1H, H-2), 5.06
(d, J 3.7 Hz, 1H, H-1), 4.97 (d, J 5.2 Hz, 1H, H-10),
4.48 (d, J 11.7 Hz, 1H, Ph–CH2–), 4.69 (d, J 11.7 Hz,
1H, Ph–CH2–), 4.29 (dd, J 3.7, 10.6 Hz, 1H, H-3),
4.23 (dd, J 5.5, 12.5 Hz, 1H, H-50-1), 3.92 (dd, J 1.1,
13.2 Hz, 1H, H-5-1), 3.88 (dd, J 2.6, 12.4 Hz, 1H, H-
50-2), 3.73 (dd, J 2.2, 13.2 Hz, 1H, H-5-2), 2.25–2.54
(m, 4H, Lev), 2.07, 2.00 (s each, 3H each, Ac, Me);
13C NMR (CDCl3): d 206.0, 171.9, 170.5, 165.6 (·2),
164.9, 128.0–137.0 (Ph–C), 100.9 (C-10), 95.7 (C-1),
73.1 (C-3), 71.3 (C-4), 69.9–70.2 (C-2, C-20, C-30,
Ph–CH2–), 67.6 (C-40), 61.2 (C-50), 60.6 (C-5), 37.7,
29.7, 27.5, 21.0; ESI-MS (m/z): 846.8 [M+Na]+ (Calcd
847.2).
3.14. 2-O-Levulinyl-3-O-(2,3,4,6-tetra-O-benzoyl-b-D-
glucopyranosyl)-4-O-acetyl-b-L-arabinopyranosyl tri-
chloroacetimidate (22)
Compound 20 was synthesized from 18 by the same pro-
cedure as that used for compound 21 and was purified
by column chromatography (2:1 petroleum ether–
EtOAc) to give 21 as white solid (81%): Rf 0.50 (1:2
petroleum ether–EtOAc). Compound 22 was synthe-
sized from 20 by the same procedure as that used for
compound 23, purified by column chromatography
(3:1 petroleum ether–EtOAc) to give 22 as a white solid
(71%): Rf 0.50 (1:1 petroleum ether–EtOAc).
3.12. Benzyl 2-O-levulinyl-3-O-(2,3,4,6-tetra-O-benzoyl-
b-D-glucopyranosyl)-4-O-acetyl-a-L-arabinopyranoside
(18)
3.15. Ursolic acid-28-O-[2,3,4,6-tetra-O-acetyl-b-D-
glucopyranosyl] ester (24)
Compound 18 was synthesized from 17 by the same pro-
cedure as that used for compound 19 and was purified
by column chromatography (2:1 petroleum ether–
EtOAc) to give a white solid (79%): Rf 0.50 (1:1 petro-
leum ether–EtOAc). 1H NMR (CDCl3): d 7.26–8.04
(m, 25H, Ph · 5), 5.88 (t, J 9.9 Hz, 1H, H-30), 5.66 (t,
1H, J 9.9 Hz, 1H, H-40), 5.48 (dd, J 7.7, 9.8 Hz, 1H,
H-20), 5.35–5.36 (m, 1H, H-4), 5.05 (dd, J 3.7, 10.2 Hz,
1H, H-2), 5.01–5.02 (m, 2H, H-1, H-10), 4.63 (d, J
12.1 Hz, 1H, Ph–CH2–), 4.58 (dd, J 3.3, 12.1 Hz, 1H,
Ursolic acid (0.20 g, 0.44 mmol) was dissolved in
CH2Cl2 (20 mL) in the presence of K2CO3 (0.122 g,
0.88 mmol), Bu4NBr (0.17 g, 0.528 mmol), and H2O
(1 mL). The vigorously stirred mixture was treated at
reflux with 2,3,4,6-tetra-O-acetyl-a-D-glucopyranosyl bro-
mide (0.22 g, 0.88 mmol) in several portions. After 8 h,
when the reaction was complete, CH2Cl2 (70 mL) was
added, and the solution was successively washed with
satd aq NaHCO3 (30 mL · 2), 5% Na2S2O3 (30 mL
· 2), and brine (30 mL · 2). The organic layer was then

P. Wang et al. / Carbohydrate Research 340 (2005) 2086–2096
2093
dried (Na2SO4) and concentrated. The residue was puri-
fied by silica gel column chromatography (3:1 petroleum
ether–EtOAc) to give 24 as a white solid (0.34 g, 99%):
33.2, 30.5, 29.8 (·2), 25.8, 24.0, 23.3, 21.1, 20.6, 18.1,
17.0 (·2), 16.4, 15.4.
20
Rf 0.24 (2:1 petroleum ether–EtOAc); ½aꢁD +32.4 (c
3.17. 3-O-[2,3,4,6-Tetra-O-benzoyl-b-D-glucopyranosyl-
(1!3)-2-O-levulinyl-4-O-acetyl-a-L-arabinopyran-
osyl]ursolic acid-28-O-[2,3,4,6-tetra-O-acetyl-b-D-gluco-
pyranosyl] ester (26)
1
0.17, CHCl3); H NMR (CDCl3): d 5.56 (d, J 8.1 Hz,
1H, H-10), 5.28 (t, J 3.3 Hz, 1H, H-12), 5.23 (t, J
9.5 Hz, 1H, H-30), 5.15 (dd, J 8.4, 9.5 Hz, 1H, H-20),
5.12 (t, J 9.9 Hz, 1H, H-40), 4.27 (dd, J 4.4, 12.5 Hz,
1H, H-60-1), 4.03 (dd, J 2.2, 12.5 Hz, 1H, H-60-2),
3.77–3.80 (m, 1H, H-50), 3.22 (dd, J 4.7, 11.3 Hz, 1H,
H-3), 2.18 (d, J 11.4 Hz, 1H, H-18), 2.07, 2.03, 2.02,
2.01 (s each, 3H each, Ac · 4), 1.07, 0.98, 0.92, 0.78,
0.76 (s each, 3H each, Me · 5), 0.93 (d, J 5.8 Hz, 3H,
H-30), 0.86 (d, J 8.2 Hz, 3H, H-29), 0.72 (d, J 11.0 Hz,
1H, H-5); ESI-MS (m/z): 808.9 [M+Na]+ (Calcd 809.4).
Compound 26 was synthesized from 24 by the same pro-
cedure as that used for compound 25, and was purified
by column chromatography (2:1 petroleum ether–
EtOAc) giving 26 as a white solid (96%): Rf 0.30 (1:2
petroleum ether–EtOAc); 1H NMR (CDCl3): d 7.27–
8.05 (m, 20H, Ph · 4), 5.95 (t, J 9.5 Hz, 1H, H-300),
5.67 (t, J 9.9 Hz, 1H, H-400), 5.54 (d, J 8.0 Hz, 1H, H-
1000), 5.45 (dd, J 8.0, 9.9 Hz, 1H, H-200), 5.26–5.27 (m,
2H, H-12, H-40), 5.23 (t, J 9.5 Hz, 1H, H-3000), 5.15–
5.18 (m, 2H, H-20, H-2000), 5.11 (t, J 9.9 Hz, 1H, H-4000),
5.06 (d, J 7.7 Hz, 1H, H-100), 4.60 (dd, J 3.3, 12.1 Hz,
1H, H-600-1), 4.51 (dd, J 4.8, 12.1 Hz, 1H, H-600-2),
4.27 (dd, J 4.4, 12.1 Hz, 1H, H-6000-1), 4.25 (d, J
7.7 Hz, 1H, H-10), 4.19–4.21 (m, 1H, H-500), 4.02 (dd, J
1.9, 12.1 Hz, 1H, H-6000-2), 3.95 (dd, J 2.2, 13.6 Hz,
1H, H-50-1), 3.89 (dd, J 3.7, 9.9 Hz, 1H, H-30), 3.76-
3.78 (m, 1H, H-5000), 3.37 (d, J 12.4 Hz, 1H, H-50-2),
2.98 (dd, J 4.4, 11.4 Hz, 1H, H-3), 2.16–2.43 (m, 4H,
CH3CH2CH2CO2), 2.17 (d, J 12.1 Hz, 1H, H-18), 2.10,
2.06, 2.05, 2.02, 2.01, 2.01 (s each, 3H each, Ac · 5),
1.03, 0.86, 0.82, 0.73, 0.65 (s each, 3H each, CH3 · 5),
0.93 (d, J 5.9 Hz, 3H, H-30), 0.85 (d, J 6.6 Hz, 3H, H-
29), 0.64 (d, J 7.3 Hz, 1H, H-5); 13C NMR (CDCl3): d
206.4, 175.3 (C-28), 171.2, 170.8, 170.6, 170.1, 169.5,
169.0, 166.0, 165.8, 165.1, 164.8, 137.1 (C-13), 128.3–
133.4 (Ph–C), 126.1 (C-12), 103.4 (C-10), 100.9 (C-100),
91.5 (C-10000), 89.7 (C-3), 76.6 (C-30), 72.8 (C-300), 72.7
(C-5000), 72.4 (C-3000), 72.2 (C-500), 72.0 (C-200), 71.4 (C-
2000), 69.9 (C-40, C-400), 69.6 (C-20), 68.0 (C-4000), 63.8
(C-50), 62.9 (C-600), 61.5 (C-6000), 55.5 (C-5), 52.5 (C-
18), 48.1, 47.5, 42.0, 39.5, 39.0, 38.8 (2C), 38.6, 37.6,
36.6, 35.9, 33.2, 30.5, 29.8, 29.7, 28.1, 27.8, 27.6, 25.8,
24.0, 23.2, 21.1, 21.0, 20.6 (2C), 18.1, 17.0, 16.9, 16.3,
15.4, 14.2.
3.16. 3-O-[2,3,4-Tri-O-benzoyl-a-L-arabinopyranosyl-
(1!3)-2-O-levulinyl-4-O-acetyl-a-L-arabinopyran-
osyl]ursolic acid-28-O-[2,3,4,6-tetra-O-acetyl-b-D-
glucopyranosyl] ester (25)
To a mixture of 24 (0.18 g, 0.23 mmol), 23 (0.30 g,
˚
0.34 mmol), and powdered 4 A molecular sieves in dried
CH2Cl2 (10 mL) was added Me3SiOTf (7.9 lL,
0.045 mmol) at ꢀ20 ꢁC under Ar protection. The mix-
ture was stirred under these conditions for 1 h, then neu-
tralized with Et3N. The solid was then filtered off and
the filtrate was concentrated under vacuum to give a yel-
low syrup, which was purified by column chromatogra-
phy (2:1 petroleum ether–EtOAc) to give compound 25
(0.30 g, 88%) as a white solid; Rf 0.50 (1:1 petroleum
20
1
ether–EtOAc); ½aꢁD +72.9 (c 0.17, CHCl3); H NMR
(DMSO): d 7.36–7.96 (m, 15H, Ph · 3), 5.78 (d, J
8.0 Hz, 1H, H-1000), 5.71 (dd, J 3.7, 9.5 Hz, 1H, H-300),
5.60–5.61 (m, 1H, H-400), 5.42 (t, J 9.5 Hz, 1H, H-3000),
5.40 (dd, J 7.0, 9.5 Hz, 1H, H-200), 5.19–5.20 (m, 1H,
H-40), 5.16 (t, J 3.3 Hz, 1H, H-12), 5.08 (d, J 7.0 Hz,
1H, H-100), 4.91–4.95 (m, 2H, H-2000, H-4000), 4.88 (dd, J
7.7, 9.5 Hz, 1H, H-20), 4.43 (d, J 7.7 Hz, 1H, H-10),
4.12-4.17 (m, 3H, H-5000, H-30, H-6000-1), 4.08 (dd, J 2.2,
13.6 Hz, 1H, H-500-1), 4.05 (d, J 11.7 Hz, 1H, H-500-2),
3.91 (d, J 9.7 Hz, 1H, H-6000-2), 3.78 (d, J 11.7 Hz, 1H,
H-50-1), 3.67 (d, J 12.5 Hz, 1H, H-50-2), 3.01 (dd, J
4.4, 12.1 Hz, 1H, H-3), 2.08–2.41 (m, 4H, Lev), 2.07
(d, J 11.3 Hz, 1H, H-18), 2.04, 2.02, 1.99, 1.98, 1.97,
1.95 (s each, 3H, Ac · 5, CH3COCH2CH2COO), 1.02,
0.82, 0.79, 0.56 (s each, 3H, Me · 4), 0.89 (d-like, 3H,
H-30), 0.80 (d, J 6.2 Hz, 1H, H-29), 0.68 (br s, 4H,
Me, H-5); 13C NMR (CDCl3): d 206.5, 175.3 (C-28),
171.1, 170.6 (·2), 170.1, 169.4, 169.0, 165.6 (·2), 165.0,
137.2 (C-13), 126.2–133.4 (Ph–C), 126.1 (C-12), 103.3
(C-10), 100.2 (C-100), 91.6 (C-1000), 89.9 (C-3), 77.0 (C-
30), 72.9 (C-3000), 72.4 (C-5000), 71.2, 70.2 (C-200), 69.9 (C-
2000), 69.2 (C-300), 68.0 (C-4000), 67.2 (C-400), 64.0 (C-50),
61.6 (C-6000), 60.4 (C-500), 55.5 (C-5), 52.6 (C-18), 48.1,
47.5, 42.0, 39.5, 39.0, 38.9, 38.8, 38.6, 37.8, 36.6, 35.9,
3.18. 3-O-[2,3,4-Tri-O-benzoyl-a-L-arabinopyranosyl-
(1!3)-4-O-acetyl-a-L-arabinopyranosyl]ursolic acid-28-
O-[2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl] ester (27)
To a solution of 25 (0.30 g, 0.20 mmol) in CH2Cl2–
MeOH (1:1, 10 mL) was added NH2NH2ÆHOAc
(0.061 g, 0.66 mmol). After being stirred at rt for 3 h,
the mixture was concentrated in vacuum to give a yellow
syrup, which was purified by column chromatography
(2:1 petroleum ether–EtOAc) to give compound 27
(0.256 g, 91%) as a white solid: Rf 0.48 (1:1 petroleum
20
1
ether–EtOAc); ½aꢁD +85.9 (c 0.17, CHCl3); H NMR
(CDCl3): d 7.33–8.05 (m, 15H, Ph · 3), 5.66–5.68 (m,

2094
P. Wang et al. / Carbohydrate Research 340 (2005) 2086–2096
2H, H-200, H-400), 5.59 (dd, J 3.7, 8.4 Hz, 1H, H-300), 5.54
(d, J 8.0 Hz, 1H, H-1000), 5.27 (t, J 3.7 Hz, 1H, H-12),
5.23 (t, J 9.2 Hz, 1H, H-3000), 5.15–5.20 (m, 3H, H-2000,
H-100, H-40), 5.12 (t, J 9.9 Hz, 1H, H-4000), 4.25–4.28
(m, 2H, H-500-1, H-6000-1), 4.21 (d, J 7.3 Hz, 1H, H-10),
4.03 (dd, J 2.2, 12.4 Hz, 1H, H-6000-2), 3.98 (dd, J 1.9,
13.6 Hz, 1H, H-50-1), 3.89 (dd, J 2.6, 12.8 Hz, 1H, H-
500-2), 3.82 (dd, J 3.3, 9.9 Hz, 1H, H-30), 3.76–3.79 (m,
2H, H-5000, H-20), 3.51 (dd, J 12.5 Hz, 1H, H-50-2), 3.12
(dd, J 4.4, 11.8 Hz, 1H, H-3), 2.18 (d, J 11.0 Hz, 1H,
H-18), 2.06, 2.02, 2.02, 2.01, 1.96 (s each, 3H each,
5 · Ac), 1.05, 0.98, 0.91, 0.80, 0.75 (s each, 3H each,
5 · Me), 0.93 (d, J 5.8 Hz, 3H, H-30), 0.85 (d, J
6.2 Hz, 3H, H-29), 0.71 (d, J 11.8 Hz, 1H, H-5). ESI-
MS (m/z): 1427.9 [M+Na]+ (Calcd 1427.6).
low syrup, which was purified by column chromatogra-
phy (2:1!1:1 petroleum ether–EtOAc) to give
compound 29 (52.8 mg, 53%) as a white solid: Rf 0.30
(1:1 petroleum ether–EtOAc); ½aꢁD +37.9 (c 0.17,
20
CHCl3); 1H NMR (CDCl3): d 7.10–8.09 (m, 15H,
Ph · 3), 5.69–5.71 (m, 1H, H-4000), 5.64–5.66 (m, 2H,
H-2000, H-3000), 5.54 (d, J 8.0 Hz, 1H, H-10000), 5.27 (t, J
3.3 Hz, 1H, H-12), 5.24 (t, J 9.1 Hz, 1H, H-30000), 5.19
(br s, 1H, H-40), 5.17 (dd, J 8.5, 9.5 Hz, 1H, H-20000),
5.12 (t, J 9.5 Hz, 1H, H-40000), 5.08 (t, J 9.5 Hz, 1H, H-
300), 5.02 (d, J 3.7 Hz, 1H, H-1000), 4.96 (t, J 9.5 Hz, 1H,
H-400), 4.93 (dd, J 8.0, 9.9 Hz, 1H, H-200), 4.68 (d, J
8.0 Hz, 1H, H-100), 4.26–4.34 (m, 3H, H-10, H-5000-1, H-
60000-1), 4.11 (dd, J 4.7, 11.7 Hz, 1H, H-600-1), 4.04 (dd,
J 2.2, 12.4 Hz, 1H, H-60000-2), 3.96–4.01 (m, 3H, H-20,
H-30, H-50-1), 3.89 (d, J 12.8 Hz, 1H, H-5000-2), 3.85
(dd, J 3.7, 12.1 Hz, 1H, H-600-2), 3.77–3.79 (m, 1H, H-
50000), 3.45 (d, J 11.8 Hz, 1H, H-50-2), 3.00 (dd, J 4.7,
11.3 Hz, 1H, H-3), 2.90–2.98 (m, 1H, H-500), 2.17 (d, J
11.3 Hz, 1H, H-18), 2.07, 2.05, 2.04, 2.02 (·3), 2.00,
1.98, 1.94 (s each, 27H, Ac · 9), 1.06, 1.04, 0.87, 0.78,
0.74 (s each, 3H each, Me · 5), 0.93 (d, J 5.8 Hz, 3H),
0.85 (d, J 6.2 Hz, 3H), 0.67 (d, J 11.3 Hz, 1H, H-5);
13C NMR (CDCl3): d 175.4 (C-28), 170.7, 170.6, 170.4,
170.1 (·2), 169.5, 169.4, 169.2, 169.0, 165.5, 165.4,
164.6, 137.2 (C-13), 126.9–133.8 (Ph–C), 126.1 (C-12),
103.8 (C-10), 99.7 (C-100), 99.4 (C-1000), 91.6 (C-10000),
90.3 (C-1), 74.6, 73.0, 72.8, 72.4, 71.7, 71.2, 69.9, 69.2,
68.1, 68.0, 66.9, 61.5, 61.4, 60.4, 55.5 (C-5), 52.6 (C-
18), 48.1, 47.5, 42.0, 39.5, 39.1, 39.0, 38.8, 38.6, 36.6,
35.9, 33.2, 30.5, 28.4, 28.1, 27.8, 25.8, 24.0, 23.3, 20.6–
21.1 (Ac · 9), 18.1, 17.0 (2C), 16.4, 15.8, 15.6; ESI-MS
(m/z): 1757.9 [M+Na]+ (Calcd 1757.7).
3.19. 3-O-[2,3,4,6-Tetra-O-benzoyl-b-D-glucopyranosyl-
(1!3)-4-O-acetyl-a-L-arabinopyranosyl]ursolic acid-28-
O-[2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl] ester (28)
Compound 28 was synthesized from 26 by the same pro-
cedure as that used for compound 27, and it was purified
by column chromatography (2:1 petroleum ether–
EtOAc) giving 28 as a white solid (90%): Rf 0.30 (1:2
20
petroleum ether–EtOAc); ½aꢁD +40.0 (c 0.17, CHCl3);
1H NMR (CDCl3): d 7.27–8.03 (m, 20H, Ph · 4), 5.88
(t, J 9.9 Hz, 1H, H-300), 5.68 (t, J 9.5 Hz, 1H, H-400),
5.54 (d, J 8.0 Hz, 1H, H-1000), 5.51 (dd, J 8.0, 9.9 Hz,
1H, H-200), 5.28 (t, J 3.3 Hz, 1H, H-12), 5.22–5.25 (m,
2H), 5.17–5.19 (m, 2H), 5.12 (t, J 9.9 Hz, 1H), 4.60
(dd, J 3.3, 12.1 Hz, 1H, H-600-1), 4.51 (dd, J 5.1,
12.1 Hz, 1H, H-600-2), 4.27 (dd, J 4.4, 12.5 Hz, 1H, H-
6000-1), 4.11–4.14 (m, 2H), 4.03 (dd, J 2.2, 12.5 Hz, 1H,
H-6000-2), 3.92 (d, J 11.7 Hz, 1H, H-50-1), 3.78 (dd, J
3.3, 9.1 Hz, 1H), 3.70 (dd, J 7.7, 9.5 Hz, 1H), 3.40 (d,
J 12.8 Hz, 1H, H-50-2), 3.08 (dd, J 4.4, 11.3 Hz, 1H,
H-3), 2.18 (d, J 10.3 Hz, 1H, H-18), 2.06 (s, 3H,
CH3CO), 2.01–2.03 (m, 12H, Ac · 4), 1.05, 0.96, 0.89,
0.78, 0.74 (s each, 3H each, CH3 · 5), 0.93 (d, J
6.2 Hz, 3H), 0.85 (d, J 6.2 Hz, 3H), 0.70 (d, J 12.1 Hz,
1H, H-5); ESI-MS (m/z): 1561.9 [M+Na]+ (Calcd
1561.6).
3.21. 3-O-{[2,3,4-Tetra-O-acetyl-b-D-xylopyranosyl-(1!
2)]-[2,3,4,6-tetra-O-benzoyl-b-D-glucopyranosyl-(1!3)]-
4-O-acetyl-a-L-arabinopyranosyl}ursolic acid-28-O-
[2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl] ester (30)
Compound 30 was synthesized from 28 by the same pro-
cedure as that used for compound 29, and was purified
by column chromatography (2:1!1:1 petroleum ether–
EtOAc) giving 20 as a white solid (97%): Rf 0.30 (1:1
20
3.20. 3-O-{[2,3,4,6-Tetra-O-acetyl-b-D-glucopyranosyl-
(1!2)]-[2,3,4-tri-O-benzoyl-a-L-arabinopyranosyl-
(1!3)]-4-O-acetyl-a-L-arabinopyranosyl}ursolic acid-28-
O-[2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl] ester (29)
petroleum ether–EtOAc); ½aꢁD +22.9 (c 0.17, CHCl3);
1H NMR (CDCl3): d 7.10–8.04 (m, 20H, Ph · 4), 5.87
(t, J 9.6 Hz, 1H, H-3000), 5.67 (t, J 9.6 Hz, 1H, H-4000),
5.54 (d, J 8.3 Hz, 1H, H-10000), 5.52 (t, J 8.7 Hz, 1H, H-
2000), 5.27 (t, J 3.2 Hz, 1H, H-12), 5.25 (t, J 9.6 Hz, 1H,
H-30000), 5.20 (br s, 1H, H-40), 5.17 (dd, J 8.2, 9.6 Hz,
1H, H-20000), 5.11 (t, J 10.1 Hz, 1H, H-40000), 5.00 (d, J
7.3 Hz, 1H, H-1000), 4.80–4.81 (m, 2H, H-200, H-300),
4.70–4.73 (m, 1H, H-400), 4.58 (dd, J 3.7, 8.7 Hz, 1H,
H-6000-1), 4.54 (dd, J 5.5, 12.4 Hz, 1H, H-6000-2), 4.42 (d,
J 7.3 Hz, 1H, H-100), 4.27 (dd, J 4.6, 12.4 Hz, 1H, H-
60000-1), 4.18 (d, J 7.3 Hz, 1H, H-10), 4.04–4.06 (m, 1H,
H-5000), 4.02 (dd, J 1.8, 10.1 Hz, 1H, H-60000-2), 3.86–
To a mixture of compound 27 (80.0 mg, 0.057 mmol)
˚
and powdered 4 A molecular sieves in dried CH2Cl2
(5 mL) was added Me3SiOTf (1.0 lL, 5.7 lmol) at
ꢀ40 ꢁC. To the mixture stirred for 30 min was added
acetylated glucopyranosyl donor 32 (168.8 mg,
0.342 mmol). The reaction continued for 12 h, and then
was quenched with Et3N. The solid was filtered off and
the filtrate was concentrated under vacuum to give a yel-

P. Wang et al. / Carbohydrate Research 340 (2005) 2086–2096
2095
3.92 (m, 2H, H-20, H-50-1), 3.81 (dd, J 3.7, 9.7 Hz, 1H,
3.23. 3-O-{[b-D-Xylopyranosyl-(1!2)]-[b-D-glucopyran-
H-30), 3.78–3.80 (m, 1H, H-50000), 3.71 (dd, J 5.5,
11.5 Hz, 1H, H-500-1), 3.27 (d, J 12.4 Hz, 1H, H-50-2),
2.99 (d, J 4.6, 11.5 Hz, 1H, H-3), 2.32 (d, J 9.6 Hz,
1H, H-500-2), 2.17 (d, J 10.3 Hz, 1H, H-18), 2.16, 2.14,
2.06, 2.04, 2.02 (·2), 2.00 (s each, 24H, Ac · 8), 1.05,
0.97, 0.88, 0.78, 0.74 (s each, 3H each, Me · 5), 0.90
(d, J 6.4 Hz, 3H, H-30), 0.85 (d, J 6.4 Hz, 3H, H-29),
0.66 (d, J 11.9 Hz, 1H, H-5); 13C NMR (CDCl3): d
175.4 (C-28), 170.6, 170.5, 170.1, 170.0, 169.6, 169.5,
169.3, 169.0, 166.0, 165.7, 165.1, 164.7, 137.2 (C-13),
127.7–133.5 (Ph–C), 126.2 (C-12), 104.1 (C-10), 100.9
(C-1000), 99.8 (C-100), 91.6 (C-10000), 90.0 (C-3), 78.2, 74.7,
72.9, 72.6, 72.4, 72.3, 72.2, 70.4, 69.9, 69.7, 68.8, 68.0,
62.9, 61.6 (2C), 55.6 (C-5), 52.6 (C-18), 48.1, 47.5,
42.0, 39.5, 39.0, 38.8, 38.7, 36.6, 35.9, 32.2, 30.5, 28.4,
28.1, 27.6, 26.0, 24.0, 23.3, 20.6–21.1 (Ac · 8), 18.1,
17.0, 16.9, 15.5; ESI-MS (m/z): 1819.9 [M+Na]+ (Calcd
1819.7).
osyl-(1!3)]-a-L-arabinopyranosyl}ursolic acid-28-
O-[b-D-glucopyranosyl] ester (2)
Compound 30 (0.079 g, 0.036 mmol) was dissolved in
MeOH–CH2Cl2 (2:1, 6 mL), and then NaOMe in
MeOH (20 mg, 50%) was added. After stirring at rt
for 4 h, the solution was neutralized with ion-exchange
resin (H+), and then filtered and concentrated. The res-
idue was purified by column chromatography (20:1!2:1
CHCl3–MeOH) to afford 2 as an amorphous solid
(0.037 g, 98%): Rf 0.30 (2:1:0.1 CHCl3–MeOH–H2O);
20
1
½aꢁD +22.6 (c 1.15, CH3OH); H NMR (Pyridine-d5): d
6.28 (d, J 8.0 Hz, 1H, H-10000), 5.43 (t-like, 1H, H-12),
5.40 (d, J 7.7 Hz, 1H, H-100), 5.31 (d, J 7.7 Hz, 1H, H-
1000), 4.74 (d, J 7.0 Hz, 1H, H-10), 4.67 (dd, J 7.0,
9.2 Hz, 1H, H-20), 4.00-4.49 (m, 16H), 3.63 (br d, J
11.7 Hz, 1H), 3.25 (dd, J 4.0, 11.8 Hz, 1H, H-3), 2.51
(d, J 11.3 Hz, 1H, H-18), 1.28, 1.19, 1.13, 1.09, 0.86 (s
each, 3H each, Me · 5), 0.92 (d, J 6.0 Hz, 3H, H-30),
0.88 (d-like, 3H, H-29), 0.76 (d, J 12.1 Hz, 1H, H-5);
13C NMR (Pyridine-d5): d 176.2 (C-28), 138.4 (C-13),
126.1 (C-12), 105.7 (C-10), 105.1 (C-100, C-1000), 95.7 (C-
10000), 89.2 (C-3), 83.7 (C-30), 79.2 (C-30000), 79.1 (C-50000),
78.9 (C-3000), 78.5 (C-300), 78.4 (C-5000), 77.4 (C-20), 76.0
(C-200), 75.3 (C-2000), 74.1 (C-20000), 71.5 (C-400), 71.3 (C-
4000), 71.1 (C-40000), 69.0 (C-40), 67.1 (C-500), 66.2 (C-50),
62.5 (C-6000), 62.2 (C-60000), 56.0 (C-5), 53.3 (C-18), 48.3
(C-17), 48.0 (C-9), 42.5 (C-14), 40.1 (C-8), 39.8 (C-20),
39.3 (C-19), 39.1 (C-4), 38.9 (C-1), 36.9 (C-10), 36.8
(C-22), 33.5 (C-7), 30.8 (C-21), 28.6 (C-15), 27.8 (C-
23), 26.7 (C-2), 24.6 (C-16), 23.8 (C-27), 23.6 (C-11),
21.3 (C-30), 18.5 (C-6), 17.6 (C-29), 17.4 (C-26), 16.5
(C-25), 15.7 (C-24); ESI-MS (m/z): 1067.5405
[M+Na]+ (Calcd 1067.5403).
3.22. 3-O-{[b-D-Glucopyranosyl-(1!2)]-[a-L-arabino-
pyranosyl-(1!3)]-a-L-arabinopyranosyl}ursolic acid-28-
O-[b-D-glucopyranosyl] ester (1)
Compound 12 (0.079 g, 0.036 mmol) was dissolved in
MeOH–CH2Cl2 (2:1, 6 mL), and then NaOMe in
MeOH (20 mg, 50%) was added. After stirring at rt
for 4 h, the solution was neutralized with ion-exchange
resin (H+), and then filtered and concentrated. The res-
idue was purified by column chromatography (20:1!2:1
CHCl3–MeOH) to afford 1 as an amorphous solid
(0.037 g, 99%): Compound 1 was also obtained from
29 by the same treatment for 12; Rf 0.25 (2:1:0.1
20
1
CHCl3–MeOH–H2O); ½aꢁD +29.7 (c 0.17, CH3OH); H
NMR (CD3OD): d 5.33 (d, J 8.2 Hz, 1H, H-10000), 5.23
(t, J 3.7 Hz, 1H, H-12), 4.83 (d, J 7.7 Hz, 1H, H-100),
4.51 (d, J 7.3 Hz, 1H, H-1000), 4.40 (d, J 7.7 Hz, 1H, H-
10), 4.00 (br s, 1H, H-40), 3.97 (dd, J 7.8, 9.2 Hz, 1H,
H-20), 3.76–3.86 (m, 7H), 3.66–3.69 (m, 1H), 3.64 (dd,
J 7.3, 9.1 Hz, 1H, H-2000), 3.52–3.56 (m, 3H), 3.49 (dd,
J 3.2, 9.2 Hz, 1H, H-3000) 3.26–3.41 (m, 4H), 3.17 (dd,
J 4.6, 11.9 Hz, 1H, H-3), 3.10 (dd, J 7.8, 9.2 Hz, 1H,
H-200), 3.05 (t, J 9.2 Hz, 1H, H-400), 2.22 (d, J 11.5 Hz,
1H, H-18), 1.32–1.40 (m, 7H), 1.10, 1.06, 0.96, 0.85,
0.82 (s each, 3H each, CH3 · 5), 0.88 (d, J 6.4 Hz,
3H), 0.75 (d, J 11.5 Hz, 1H, H-5); 13C NMR (CD3OD):
d 177.9 (C-28), 139.1 (C-13), 127.2 (C-12), 106.1 (C-10),
105.8 (C-1000), 103.6 (C-100), 95.7 (C-10000), 91.9 (C-3), 84.1
(C-30), 78.6, 78.4, 78.3 ,78.2, 76.5 (C-20), 76.1 (C-200),
74.4 (C-3000), 73.9 (C-20000), 72.8 (C-2000), 72.5, 71.2, 70.0
(C-40), 69.9 (C-4000), 67.2 (C-50), 66.6, 63.7, 62.5, 57.0,
54.8, 54.2, 43.3, 41.0, 40.6, 40.3, 40.1, 37.8, 37.5, 34.3,
31.7, 29.3, 28.3, 27.2, 25.2, 24.4, 24.0, 21.5, 19.3, 17.9,
16.9, 16.1; ESI-MS (m/z): 1067.5420 [M+Na]+ (Calcd
1067.5403).
Acknowledgments
This work was supported by the National Natural Sci-
ence Foundation of China (No. 30400564).
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