Synthesis of glycosides of lupane-type triterpene acids

Article abstract of DOI:10.1023/B:CONC.0000018113.79735.34

A preparative synthesis of glucosides of the lupane-type triterpene acids betulinic, dihydrobetulinic, betulonic, dihydrobetulonic, and 3,20-dioxo-30-norlupan-28-oic was proposed. Glycosylation of 3-hydroxyacids by α-acetobromoglucose (ABG) with Ag₂O was performed in pyridine (Py) to form glycosides at C-28, repeated glycosylation of which by these same reagents but in CH₂Cl₂ generated a glycoside bond at C-3 to form bisglucosides. 28-Glucosides of ketoacids were formed in high yields in both Py and CH₂Cl₂.

Full text of DOI:10.1023/B:CONC.0000018113.79735.34

Chemistry of Natural Compounds, Vol. 39, No. 6, 2003
SYNTHESIS OF GLYCOSIDES OF LUPANE-TYPE TRITERPENE ACIDS
N. F. Samoshina, M. V. Denisenko,
V. A. Denisenko, and N. I. Uvarova
UDC 547.917+547.918+547.597
A preparative synthesis of glucosides of the lupane-type triterpene acids betulinic, dihydrobetulinic,
betulonic, dihydrobetulonic, and 3,20-dioxo-30-norlupan-28-oic was proposed. Glycosylation of
3
-hydroxyacids by α-acetobromoglucose (ABG)with Ag O was performed in pyridine (Py)toformglycosides
2
at C-28, repeated glycosylation of which by these same reagents but in CH Cl generated a glycoside bond
2
2
at C-3 to form bisglucosides. 28-Glucosides of ketoacids were formed in high yields in both Py and CH Cl .
2
2
Key words: betulin, betulinic acid, glucosides, PMR and 13C NMR.
The biological activities of betulinic and platanic acids as anti-HIV agents that was previously reported [1] have
stimulated interest in the synthesis of other lupane derivatives with potentially interesting biological activities [2-11]. Several
glycosides of lupane derivatives were synthesized [3, 5, 11-16]. It should be noted that glycosides of many triterpenoids and
steroids are biologically more available to living organisms than their starting aglycons [17]. The platform compound in most
syntheses based on lupanetriterpenesisbetulin, 20(29)-lupen-3β,28-diol, which occursin significantquantitiesin the outer bark
of various white-birch species, from which it is easily isolated pure and reproducibly as a natural product [18-21]. It must be
emphasized that betulin can be obtained in significant quantities as a side product during processing of birch wood from which
the bark has not been stripped [18, 21].
R
R
R
OH
OGlc(Ac)4
OGlc(Ac)
4
O
O
O
HO
(Ac)4GlcO
1
, 6
2, 7
4, 9
R
OH
O
OGlc
OGlc
O
O
3
, 8
GlcO
5, 10
GlcO
11
R
R
R
OH
OGlc
OGlc(Ac)4
O
O
O
O
O
1
2, 15, 18
13, 16, 19
14, 17
AcOH2C
AcO
AcO
HOH2C
HO
HO
O
O
=
Glc(Ac)
= Glc
4
OAc
OH
1
-5, 12-14: R=-CH(CH )=CH ; 6-11, 15-17: R=-CH(CH ) ; 18, 19: -C(CH )=O
3 2 3 2 3
Pacific Institute of Bioorganic Chemistry, Far-East Division, Russian Academy of Sciences, 690022, Vladivostok, pr.
00-Let Vladivostoku, 159, fax (4232) 31 40 50, e-mail: mvdenis@piboc.dvo.ru. Translated from Khimiya Prirodnykh
1
Soedinenii, No. 6, pp. 475-481, November-December, 2003. Original article submitted November 27, 2003.
©
0
009-3130/03/3906-0575$25.00 2003 Plenum Publishing Corporation
575

13
TABLE 1. C NMR Spectra of 2, 4, 5, 7, 9, 10, 12, and 13
Compound
C atom
2
4
5
7
9
10
12
13
1
2
3
4
5
6
7
8
9
39.0
27.7
79.0
39.0
55.6
18.5
34.7
41.0
50.8
37.5
21.2
25.8
38.5
42.6
30.7
32.0
57.0
46.9
49.5
150.1
29.9
36.7
28.2
15.5
16.2
16.2
14.9
174.0
109.7
19.6
39.0
25.9
90.7
39.2
56.0
18.5
34.8
41.0
50.9
37.2
21.2
26.1
38.5
42.7
30.7
32.0
57.0
46.9
49.6
150.1
29.9
36.7
27.8
16.2
16.2
16.2
14.8
174.0
109.7
19.6
39.2
26.3
88.9
39.2
56.1
18.6
34.9
41.2
51.0
37.5
21.3
26.8
38.7
42.9
31.4
33.0
56.6
47.8
50.0
150.1
30.3
37.2
28.2
16.8
16.5
16.3
15.0
178.4
109.6
19.6
39.1
27.7
79.1
39.1
55.7
18.6
34.9
41.1
50.7
37.5
21.2
27.2
38.5
42.9
30.0
32.0
57.5
49.0
44.4
30.0
23.0
37.2
28.2
15.5
16.3
16.3
14.9
39.1
27.2
90.7
39.1
56.0
18.5
34.9
41.1
50.7
37.2
21.3
26.2
38.4
42.9
30.0
32.0
57.5
49.0
44.4
30.0
23.0
37.2
27.9
16.4
16.2
16.4
14.9
174.3
22.8
14.9
39.2
26.3
88.7
38.8
55.7
18.2
34.6
40.9
50.4
37.5
21.0
27.1
38.2
42.7
29.7
32.4
56.6
49.0
44.5
29.8
23.0
36.9
27.8
16.4
16.0
15.9
14.5
178.1
23.0
14.4
39.6
34.2
218.4
47.4
55.0
19.7
33.6
39.6
49.9
37.1
21.4
25.5
38.6
42.5
30.6
32.2
56.5
47.4
49.9
150.4
30.6
37.1
26.7
21.0
15.9
16.0
14.7
182.5
109.8
19.6
39.6
34.2
218.0
47.4
55.0
19.7
33.8
39.6
49.9
37.0
21.4
25.6
38.3
42.6
30.6
31.7
56.8
46.8
49.9
150.0
29.8
36.5
26.6
21.1
16.0
16.0
14.7
174.3
109.8
19.7
1
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
174.4
22.8
14.9
Our goal was to develop simple preparative methods for synthesizing glycosides of betulinic (1) and dihydrobetulinic
6) acids in addition to betulonic (12), dihydrobetulonic (15), and 3,20-dioxo-30-norlupan-28-oic (18) acids for subsequent
(
research on their biological activities.
Monoglucosides at C-28 were prepared in two steps; monoglucosides at C-3 and bisglucosides in three steps from
betulinic and dihydrobetulinic acids. Glycosylation of 1 and 6 in Pybytetra-O-acetyl-α-D-glucopyranosylbromide (ABG) with
Ag O gave monoglucosides 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl-3β-hydroxy-20(29)-lupen-28-oate(2)and2,3,4,6-tetra-O-
2
acetyl-β-D-glucopyranosyl-3β-hydroxylupan-28-oate(7), which weresaponifiedbyNaOCH in CH OHtofree28-O-glucosides
3
3
3
and 8. Repeated glycosylation of 2 and 7 by ABG with Ag O in CH Cl afforded the corresponding acetates of 3,28-
2 2 2
bisglucosides 4 and 9. Basic hydrolysis of 4 and 9 byheating with KOH in CH OH gave the corresponding 3-O-β-D-glucosides
3
of betulinic and dihydrobetulinic acids 5 and 10. Saponification by NaOCH in CH OH at room temperature of 9 gave free
3
3
bisglucoside 11.
Glycosylation of betulonic 12, dihydrobetulonic 15, and 3,20-dioxo-30-norlupan-28-oic 18 acids by ABG both in Py
and CH Cl gave the corresponding 28-glucosides 13, 16, and 19 in high yields with insignificant recoveryofthe starting acids.
2
2
The structures of the products were proved using PMR and 13C NMR spectra (Tables 1-5).
Thus, we proposed a convenient synthesis for glucosides oflupane-type triterpene acids that is suitable on a preparative
scale.
Glycoside 5 exhibited stimulatory and glycoside 10 inhibitory activities for growth of root sprouts of Cucumis
sativus L. [11].
5
76

1
3
TABLE 2. C NMR Chemical Shifts of 15-19, Platanic Acid (PA), and its 3-Acetate (APA)
Compound
C atom
15
16
17
18
19
PA
APA
1
2
3
4
5
6
7
8
9
39.6
34.2
218.4
47.4
54.9
19.7
33.7
40.7
49.7
36.9
21.4
26.9
38.4
42.7
32.1
22.8
56.9
48.7
44.2
29.8
29.7
37.5
26.7
21.4
16.0
16.0
14.7
182.7
14.7
14.6
39.6
34.2
218.0
47.4
55.0
19.7
33.8
40.7
49.7
36.9
21.4
26.9
38.2
42.7
31.7
22.6
57.2
48.6
44.1
29.8
29.7
36.9
26.7
21.1
20.2
20.2
20.2
174.5
15.0
15.1
39.7
34.8
218.0
47.4
55.1
19.7
33.9
40.9
49.8
37.0
21.6
26.7
38.3
42.8
31.9
22.8
57.3
49.0
44.3
29.9
29.8
37.1
27.1
21.2
16.0
15.9
14.8
174.8
14.8
14.7
39.6
34.1
218.0
47.3
54.8
19.7
33.5
40.6
49.7
36.9
21.4
27.3
37.7
42.4
31.5
28.3
56.3
49.1
51.2
212.0
29.7
36.7
26.8
21.0
16.0
16.0
16.0
182.0
30.1
39.4
34.0
217.8
47.2
54.7
19.6
33.5
40.5
49.7
36.8
21.4
27.2
37.3
42.3
31.0
28.0
56.6
48.6
50.5
211.6
29.6
36.1
26.6
21.0
16.0
15.6
14.6
174.1
30.1
38.7
34.2
79.0
38.9
55.3
18.3
34.2
40.6
50.4
37.3
20.9
27.3
38.7
42.3
31.5
28.3
56.3
49.3
51.3
212.4
29.8
37.2
27.3
18.3
16.1
16.0
15.4
181.4
30.2
38.4
34.2
80.9
49.3
55.4
18.2
34.2
40.6
50.3
37.2
21.4
28.0
37.6
42.3
31.5
28.3
56.3
50.3
51.3
212.2
29.8
36.8
27.2
20.9
16.5
16.2
16.0
182.2
30.2
1
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
TABLE 3. PMR Chemical Shifts of 2, 4, 5, and 12-14
Compound
Protons
2
4
5
12
13
14
CH3
0.75 s
0.72 s
0.82 s
0.89 s
0.95 s
0.75 s
1.0 s
1.05 s
1.10 s
0.93 s
0.97 s
0.99 s
1.02 s
0.93 s
0.97 s
1.02 s
1.06 s
0.81 s
1.01 s
1.02 s
0
0
0
.82 s
.89 s
.96 s
1.12 s
1.07 s
1.13 s
=
CH2
4.60 m
4.61 br.d
4.75 br.d
2.95 m
4.60 m
4.78 br.d
2.7 m
4.61 m
4.74 br.d
3.02 td
4.73 m
4.74 m
2.9-3.0 t,
4.75 m
4.90 m
3.36-3.47 td,
J = 10.7; 10.7; 4.6
4.74 br.d
H-19
2.94 m
J = 11.0; 11.0; 4.4
H-3a
H-30
3.18 dd
1.68 s
3.05 dd
1.68 s
3.5 m
1.8 s
1.7 s
1.7 s
1.7 s
577

TABLE 3. (Continued)
Protons
Compound
2
4
5
12
13
14
Carbohydrate part
4.37
1
H
5.69 d, J = 8
5.20 dd
5.7 d, J = 8
5.71 d, J = 8
4.21 d, J = 8.2
4.55 d, J = 8
2
H
5.05 dd
4.9-5.0
5.21 dd, J = 8.5; 8.3
4.37 dd, J = 8.7; 8.85
5
.18 dd
3
4
H
H
5.28 t
5.15 dd
5.20 t, 5.25 t
5.00 dd
4.9-5.0
4.4-4.45
5.29 t, J = 9.3; 3.0; 9.0
5.16 dd, J = 5.2; 9.4
4.,42 t, J = 9.6; 8.7
4.33 dd, J = 6.1; 8.6
5
.15 dd
3.68 m
.83 m
5
H
3.83 m
4.07 dd
3.95-4.1
4.2-4.3
3.84 m
3.83-3.91 m
4.07 m
3
6
2
H
4.08 dd
4.11 dd
4.07 dd, J = 12.4; 2.3
4.32 dd, J =12.5; 4.5
4.31 dd
4
4
.25 dd
.32 dd
OAc
2.02 s
2.01 s
2.02 s
2.03 s
2.02 s
2.04 s
2.08 s
2
2
.04 s
.08 s
2.08 s
TABLE 4. PMR Chemical Shifts of 15-19, PA, and APA
Compound
Protons
15
16
17
18
19
PA
APA
CH3
0.94 s
0.93 s
0.94 s
0.95 s
0.98 s
0.93 s
0.96 s
0.96 s
1.02 s
1.07 s
0.91 s
0.95 s
1.01 s
1.01 s
1.07 s
3.25 m
0.91 s
1.00 s
1.01 s
1.06 s
0.76 s
0.82 s
0.91 s
0.97 s
1.01 s
3.25 m
0.83 s
0.85 s
0.91 s
1.00 s
0
1
1
.97 s
.02 s
.07 s
1.02 s
H-19
H-29
H-30
3.18 m
3.25 m
0.76 d
0.87 d
0.75 d
0.85 d
0.76 d
0.86 d
Carbohydrate part
5.58 d, J = 9
1
H
5.69 d; J = 8.1
5.15 dd; J = 9.0
5.23 dt, J = 9.0
5.16 dd; J = 9.0
3.83 m
5.7 d, J = 9.3
5.25 dd, J = 9.3
5.28
2
H
3
H
H4
5.15 dd, J = 9.0
5
H
6
2
H
4.07 dd
4.07 d, J = 2.3
4.11 d, J = 2.4
2.04 s
4.31 dd
OAc
2.02 s
2
2
2
.02 s
.03 s
.07 s
2.04 s
2.08 s
2.18 s
5
78

13
TABLE 5. C NMR Spectra of the Carbohydrate Part of 2, 4, 5, 7, 9, 10, 13, 16, 17, 19
Compound
Atom
3
28
3
28
2
4 , 4
5
7
9 , 9
10
13
16
17
19
C-1
C-2
C-3
C-4
C-5
C-6
OAc
91.3
102.9
106.5
91.3
103.0
91.3
72.2
70.4
71.9
72.8
69.3
68.6
73.3
73.3
62.6
61.9
170.3
170.1
169.9
169.9
169.9
169.2
168.8
168.8
20.7
20.7
20.6
20.6
20.6
20.6
20.6
20.6
105.8
91.2
91.1
93.6
91.2
9
1.3
72.1
0.3
71.8
2.8
69.3
8.5
73.2
3.2
62.6
1.9
70.3
72.8
68.5
73.2
61.8
170.2
72.0
75.7
63.2
77.9
63.2
73.3
72.8
68.6
70.3
61.9
71.3
75.0
62.4
77.0
62.4
70.0
72.9
68.3
73.2
61.8
70.0
72.6
68.1
73.0
61.6
70.3
76.1
69.8
72.7
67.8
72.5
61.4
7
7
6
73.0
67.2
7
6
170.2
170.2
169.8
169.8
169.1
169.1
168.7
168.7
170.3
169.9
169.2
168.8
20.6
20.6
20.6
20.6
170.6
170.2
169.4
168.9
20.7
20.6
20.6
20.6
170.6
170.2
169.5
169.0
20.7
20.6
20.6
20.6
170.4
170.1
168.9
169.3
20.6
20.5
20.5
20.5
1
1
1
69.8
69.1
68.7
2
2
2
2
0.6
0.6
0.6
0.6
2
2
2
2
2
2
2
2
0.7
0.7
0.6
0.6
0.6
0.6
0.6
0.6
_
_____
3
28
-
3-O-Glc(Ac)4; - 28-O-Glc(Ac)4.
EXPERIMENTAL
13C NMR and PMR spectra were recorded on Bruker AVANCE-300 (75 and 300 MHz, respectively) spectrometers
in CDCl (Me Si internal standard). Chemical shifts were calculated for PMR spectra relative to the Me Si signal; for
3
4
4
13
13
C spectra, the solvent signal (CDCl , 77.1 ppm). The multiplicity of the C signals was determined from DEPT-135
3
experiments by the standard method. Homonuclear 2D proton—proton correlation spectra COSY-45 and 2D heteronuclear
correlation spectra HSQC and HMBC were also recorded by standard methods. HMBC experiments were optimized for
nJHC 10 Hz. Melting points were determined on a Boetius microstage and are uncorrected. Sorbfil plates (Russia) were used
for TLC. Column chromatography was performed over SiO using solvent systems hexane:acetone from 40:1 to 5:1 and
2
C H :CH OH from 15:1 to 5:1. Specific rotation was determined to an accuracy of ±1° on a Perkin—Elmer 141 polarimeter
6
6
3
3
3
in monochromatic light from a Na lamp (D-line) in 1cm cuvettes (concentration expressed in g/cm ) and optical pathlength
1
.0002 dm in CHCl or C H N solutions. Reaction mixtures for glycosylation were stirred on a magnetic stirrer at room
3 5 5
temperature.
Betulin was isolated from the acetone extract of the outer bark of Betula platyphylla Sukacz. [B. mandshurica (Regel)
2
5
Nakai] as before [11], mp 247-248°C (EtOH), lit. [21] mp 250-251°C. Betulinic acid (1), mp 292°C (EtOH), [α]D +9°
(
c 0.004, CHCl ), lit. [12] mp 304-306°C (EtOH), [α]D20 +4 ± 3° (c 0.41, CHCl ), was synthesized by oxidation of
3
3
3
β-acetoxybetulin by t-butylchromate prepared by the literature method [22] with subsequent saponification by KOH (10%) in
579

CH OH. Betulin was acetylated with a mixture of Ac O and C H N by the usual method to produce in about 90% yield
3
2
5 5
3
3
β,28-diacetoxybetulin, which was then hydrogenated in AcOH over Pd/C by the literature method [23] to
β,28-diacetoxydihydrobetulin, mp 256-257°C (C H —EtOH), lit. [23] mp 259°C (CH Cl —EtOH), and partially saponified
6
6
2
2
by KOH in CH OH to 3β-acetoxydihydrobetulin, mp 260-262°C (CH OH), lit. [24] mp 258-259°C, [α] -5.1°, or completely
3
3
D
to dihydrobetulin, mp 276-278°C (EtOH), lit. [23] mp 277-278°C (EtOH), [α] -20° (c 0.9, Py). 3β-Acetoxydihydrobetulin
D
was oxidized by RuO /NaIO with vigorous stirring in the two-phase system EtOAc—H O by a method analogous to that in
4
4
2
+
the literature [25] to afford 3β-acetoxydihydrobetulinic acid in 83% yield, mp 306-307°C, mass spectrum 500 [M] ; lit. [26]
mp 311-312.5°C. Saponification by KOH in CH OH of 3β-acetoxydihydrobetulinic acid gave dihydrobetulinic acid, mp 305-
3
3
06°C (EtOH), [α]D25 +4° (c 0.0042, CHCl ); lit. [26] mp 323-324.5°C, [α] -28.8° (dioxane). Oxidation of betulin by CrO
3
D
3
25
in AcOH according to the literature [27] gave betulonic acid 12, mp 217-221°C (CH CN), [α]
+25° (c 0.01, CHCl ), lit.
3
D
3
[27] mp 245-248°C.
Oxidation of dihydrobetulin by RuO /NaIO in EtOAc—H O [28] by a method analogous to that in the literature [25]
4
4
2
25
afforded dihydrobetulonic acid, mp 261-263°C (EtOH), [α]D +19° (c 0.01, CHCl ), [α] +11.7° (c 0.027, CHCl ); lit. [23]
3
578
3
mp 258-260°, [α] +12.3°; [29] mp 250-253°C.
D
3
,20-Dioxo-30-norlupan-28-oic Acid (18). A solution of Ru(OH)Cl (103.2 mg, 0.45 mmol) with a suspension of
3
betulin (5.06 g, 11.43 mmol) in EtOAc (200 mL) was vigorously stirred for 9 h, treated dropwise with NaIO (15.3 g,
4
7
1.5 mmol) in H O (150 mL), and left overnight without stirring. The aqueous layer was separated and extracted with EtOAc
2
(3 × 25 mL). The combined EtOAc extracts were treated with stirring with i-PrOH (5 mL) to decompose the excess of oxidant
and filtered to remove the black precipitate of RuO × H O. The filtrate was dried over anhydrous CaCl and evaporated to
2
2
2
dryness in a rotary evaporator. The resulting colored polycrystalline solid was dissolved in C H (200 mL) and filtered from
6
6
the black precipitate of RuO impurities through a sintered-glass filter (16 pore). Then, impurities of colloidal RuO were
2
2
removed by filtration through a 1-cm-thick Al O layer on another sintered-glass filter. The resulting C H filtrate was stirred
2
3
6 6
and treated with KOH solution (10 mL, 10%). The C H was decanted from the resinous precipitate of triterpene-acid salts.
6
6
The solid was dissolved in EtOH (100 mL) and treated with HCl (100 mL, 15%) and H O (300 mL). The isolated resinous
2
product was dissolved in EtOH (100 mL), partially decolorized by treatment with activated carbon, filtered, and evaporated to
dryness. The resulting solid (2.1 g) was chromatographed over a SiO column with elution by hexane:acetone mixtures
2
[
[
2
(30:1)→(5:1)] to isolate 3,20-dioxo-30-norlupan-28-oic acid (18) (640 mg, 1.4 mmol, 12.3%), mp 223-224°C (EtOH),
α]D25 +31° (c 0.01, CHCl ); lit. [30] Me-ester, mp 162-164°, [α] +2° (c 1.04, CHCl ); and 3β-hydroxy-20-oxo-30-norlupan-
3
D
3
25
8-oic (platanic) acid (800 mg, 1.75 mmol, 15%), mp 280-282°C (EtOH), [α]D -31° (c 0.01, CHCl ); [α] -29.4° (c 0.014,
3 578
CHCl ); lit. [30] mp 285-287°C, [α] -51° (c 1, CHCl ).
3
D
3
2
,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl-3β-hydroxylup-20(29)-en-28-oate (2). A mixture of 1 (182 mg,
0
.4 mmol), ABG (328 mg, 0.8 mmol), and Ag O (94 mg, 0.4 mmol) in Py (5 mL) was stirred for 3 h, diluted with CHCl ,
2
3
filtered, and evaporated. The solid was chromatographed over a SiO column using hexane:acetone [(20:1)→(10:1)] to isolate
2
25
2
(296 mg, 94.0%), mp 125-130°C (CH OH), [α]
-10° (c 0.0046, CHCl ); lit. [12] mp 124-126 C, [α] -3 ± 4° (c 0.76,
3 D
3
D
EtOH).
General Method for Deacetylation of 28-(2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyloxy)-derivatives.
Approximately 1 mmol of tetraacetate glucoside was dissolved in CH OH (30 mL), treated with NaOCH in CH OH (1 mL,
3
3
3
+
0
.1 N), held for 3-4 h at room temperature (TLC monitoring), neutralized with KU-2-8 H ion-exchange resin, and evaporated
to give free glucoside in ~95% yield.
β-D-Glucopyranosyl-3β-hydroxylup-20(29)-en-28-oate (3). Saponification of2bytheusual methodgave3, mp 229-
2
32°C (EtOH), [α]D25 +5° (c 0.005, Py); lit. [3] mp (amorph.), [α] 0 ± 2° (c 0.16, CH OH); lit. [12] mp 213-216°C (CH OH),
D 3 3
[
α] -2 ± 4° (c 0.43, EtOH).
D
2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl-3β-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-lup-20(29)-en-28-
oate (4). A mixture of 2 (390 mg, 0.5 mmol), ABG (1110 mg, 2.7 mmol), and Ag O (632 mg, 2.7 mmol) in CH Cl (10 mL)
2
2
2
was stirred for 48 h, diluted with CHCl , filtered, and evaporated. The solid was washed with hot water to remove sugars and
3
chromatographed over SiO usinghexane:acetone [(20:1)→(5:1)] toisolate unreacted 2 (83 mg, 21.1%) and 4 (340 mg, 60.8%),
2
mp 225-230°C (EtOH); lit. [3] mp 225-231°C (CH Cl :Et O), [α] +1 ± 2° (c 0.46, CHCl ).
2
2
2
D
3
3
β-(β-D-Glucopyranosyloxy)-lup-20(29)-en-28-oic Acid (5). Compound 4 (80 mg, 0.07 mmol) was dissolved in
CH OH (10 mL), treated with KOH in CH OH (4 mL, 10%), heated on a boiling-water bath for 5 h, neutralized with
3
3
5
80

KU-2-8 H+ ion-exchange resin, evaporated, and washed with water to isolate 5 (47 mg, 74.4%), mp amorph., [α]D25 -5°
(
c 0.005, Py).
2
,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl-3β-hydroxylupan-28-oate (7). A mixture of6 (916 mg, 2mmol), ABG
(
1644 mg, 4 mmol), and Ag O (936 mg, 4 mmol) in Py (10 mL) was stirred for 6 h, left for 1 d, diluted with CHCl , filtered
2
3
to remove AgBr, evaporated, and washed with hot water. The solid was recrystallized from CH OH to afford 7 (771 mg,
3
4
8.8%). The mother liquor was evaporatedandchromatographedover SiO usinghexane:acetone[(20:1)→(10:1)]. Theoverall
2
yield of chromatographically pure 7 was 1051 mg (66.5%), mp 150-153° (EtOH), [α]D25 -13° (c 0.01, CHCl3).
β-D-Glucopyranosyl-3β-hydroxylupan-28-oate (8). Saponification of 7 by the usual method gave 8, mp 294-297°C
(
EtOH), [α]D25 -3° (c 0.01, Py); lit. [3] mp 243-244°C (CH OH), [α] -21 ± 2° (c 0.17, CH OH).
3 D 3
2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl-3β-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-lupan-28-oate (9).
A mixture of 6 (229 mg, 0.5 mmol), ABG (1233 mg, 3 mmol), and Ag O (702 mg, 3 mmol) in CH Cl (10 mL) was stirred
2
2
2
for 2 d and chromatographed over SiO in hexane:acetone [(30:1)→(5:1)] to afford 6 (64 mg, 27.9%), 7 (190 mg, 48.2%), and
2
(80 mg, 14.3%), mp 251-252° (EtOH), [α]D2 -38° (c 0.01, CHCl3).
5
9
3
β-(β-D-Glucopyranosyloxy)-lupan-28-oic Acid (10). Compound 9 (143 mg) was dissolved in CH OH (15 mL),
3
+
treated with KOH in CH OH (9 mL, 10%), heated at 50°C for 8 h, neutralized with KU-2-8 H , evaporated, and washed with
water to remove sugars and isolated 10 (75 mg, 67.2%), mp amorph., [α]D25 +6° (c 0.005, Py).
3
β-D-Glucopyranosyl-3β-(β-D-glucopyranosyloxy)-lupan-28-oate (11). A mixture of 6 (1 mmol), ABG (4 mmol),
and Ag O (936 mg, 4 mmol) in CH Cl (10 mL) was stirred for 3 d and worked up as usual. The solid, which contained a
2
2
2
+
mixture of 7 and 9, was treated with CH OH (30 mL) and KOH in CH OH (8 mL, 10%), neutralized by KU-2-8 H ion-
3
3
exchanger, evaporated, washed with water to remove sugars, and chromatographed over SiO with elution by C H :CH OH
2
6
6
3
[
(15:1)→(5:1)] to afford 11 (163 mg, 21%), mp 236-238°C (EtOH), [α]D25 -5° (c 0.005, Py) and 8 (389 mg, 63.3%).
β-D-Glucopyranosyl-3-oxolup-20(29)-en-28-oate (13). A mixture of 12 (456 mg, 1 mmol), ABG (822 mg, 2 mmol),
and Ag O (468 mg, 2 mmol) in Py (10 mL) was stirred for 8 h, diluted with (CH ) CO, and poured into a beaker with ice. The
2
3 2
precipitate was filtered off, placed on SiO , and eluted with (CH ) CO (to remove AgBr). The eluate was evaporated. The solid
2
3 2
was dissolved in EtOH (20 mL) containing KOH in EtOH (20 mL, 0.1 N). The saponified product was chromatographed over
SiO using C H :CH OH [(100:1)→(25:1)] to afford 13 (454 mg, 73.4%), mp 255° (EtOH), [α]D25, +16° (c 0.01, Py) and
2
6
6
3
starting 12 (120 mg, 26.3%). Glycosylation of 12 in CH Cl under these same conditions gave 81.6% 13 and 11.2% starting
2
2
1
2 after analogous treatment.
,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl-3-oxolupan-28-oate (16). A mixture of 15 (458 mg, 1 mmol), ABG
820 mg, 2 mmol), and Ag O (468 mg, 2 mmol) in Py (10 mL) was stirred for 5 h, diluted with (CH )CO, filtered, and
2
(
2
3
chromatographed over a column of SiO using petroleum ether:acetone [(40:1)→(25:1)] to afford starting 15 (42 mg, 9.2%)
2
and 16 (712 mg, 90.4%), mp 158-160° (EtOH), [α]D25 +4° (c 0.01, CHCl3).
2
,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl-3,20-dioxo-30-norlupan-28-oate (19). A mixture of 18 (229 mg,
0
.5 mmol), ABG (820 mg, 2 mmol), and Ag O (468 mg, 2 mmol) in Py (5 mL) was stirred for 5 h and chromatographed over
2
25
SiO using petroleum ether:acetone [(40:1)→(10:1)] toafford 19 (290 mg, 73.6%), mp 209-211 C(EtOH), [α]D +13°(c 0.01,
2
CHCl3).
ACKNOWLEDGMENT
We thank the Head of the Laboratory of Chemotaxonomy of the PIBOC, FED, RAS Academician P. G. Gorovoi and
I. G. Gavrilenko for help with determining the birch species.
The work was supported by RF Presidential Grant No. NSh-123.2003.3 and RFBR Grant No. 030449521.
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