Synthesis, encapsulation and antitumor activity of new betulin derivatives

Article abstract of DOI:10.1002/ardp.201000232

Novel betulin derivatives were prepared and tested for their antitumor activity. Starting from 3-O-acetyl- or 3-O-methyl-betulinic aldehyde, the synthesis of C-28 ethynyl derivatives was performed; their subsequent transformation with several 1,3-dipolarophiles afforded pyrazoles and 1,2,3-triazoles. Their screening for antitumor activity was performed in a panel of 15 human cancer cell lines by a colorimetric SRB-assay. Thereby, several compounds revealed a higher cytotoxicity than betulinic acid. In addition, the encapsulation of the lead structure 7 into liposomes was investigated. The results from a dye exclusion test and from DNA laddering experiments provided evidence for an apoptotic cell death. Betulin derivatives bearing an ethynyl side chain were synthesized. These compounds possess quite promising antitumor activity by triggering apoptosis. Encapsulation in liposomes is investigated.

Full text of DOI:10.1002/ardp.201000232

Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
37
Full Paper
Synthesis, Encapsulation and Antitumor Activity of New
Betulin Derivatives
´
Rene Csuk, Alexander Barthel, Ronny Sczepek, Bianka Siewert, and Stefan Schwarz
¨
Martin-Luther-Universitat Halle-Wittenberg, Organische Chemie, Halle (Saale), Germany
Novel betulin derivatives were prepared and tested for their antitumor activity. Starting from 3-O-
acetyl- or 3-O-methyl-betulinic aldehyde, the synthesis of C-28 ethynyl derivatives was performed; their
subsequent transformation with several 1,3-dipolarophiles afforded pyrazoles and 1,2,3-triazoles.
Their screening for antitumor activity was performed in a panel of 15 human cancer cell lines by a
colorimetric SRB-assay. Thereby, several compounds revealed a higher cytotoxicity than betulinic
acid. In addition, the encapsulation of the lead structure 7 into liposomes was investigated. The results
from a dye exclusion test and from DNA laddering experiments provided evidence for an apoptotic
cell death.
Keywords: Antitumor activity / Betulin / Betulinic acid / 1,3-Dipolar-cycloaddition / Liposomes / SRB assay
Received: August 12, 2010; Revised: August 30, 2010; Accepted: September 2, 2010
DOI 10.1002/ardp.201000232
Introduction
mitochondria leads to an increased permeability and releases
cytochrome c and AIF to the cytosol [8, 9], thus, triggering the
caspase cascade and nuclear fragmentation. Furthermore,
the generation of reactive oxygen species (ROS) [10] was
observed, that is associated with an up-regulation [11] of
p38 and SAP/JNK kinases.
Cancer is still one of the leading causes of death. The index of
cancer cure is often low and its treatment is still a challenge.
Triterpenes represent an important class of natural com-
pounds. In the forests of Europe, Asia and North America
betulin and betulinic acid (Fig. 1) [1, 2] are found in the
external bark of birches and sycamore trees. These lupane-
type triterpenes have recently been investigated for their
various pharmacological and medicinal properties, among
them antitumor and anti-HIV activity.
Herein, we present a synthetic approach to new betulin
derived compounds bearing an ethynyl side chain at the C-28
position. In addition, these compounds were used for the
synthesis of heterocyclic compounds by 1,3-dipolar cycload-
ditions with diazoalkanes and azides. The antitumor activity
of the compounds was studied using a colorimetric sulpho-
rhodamin B assay (SRB assay) applying 15 different human
cancer cell lines.
Antiviral potency of betulinic acid (BA) derivatives is linked
to a particular action by the inhibition of the virus-cell fusion
at the gp41-gp120 interface [3, 4] or by altering the process of
cell maturation [5, 6] by interfering the CA-SP1 junction in
the Gag processing. Interestingly, BA showed in an animal Results and discussion
model a selective cytotoxicity for melanoma cells with no
acute or chronic side effects to normal cells even at doses of
500 mg/kg [7]. The apoptotic action of BA follows an intrinsic
The synthesis of acetylenic compounds started from 3-O-ace-
tyl- (1) or 3-O-methyl betulinic aldehyde (2) [12, 13] (Scheme 1).
Their reaction with ethynyl magnesium bromide [14]
afforded the corresponding 28-ethynyl-betulinols as an insep-
arable mixture of diastereomers; hence, a direct transfor-
mation to compounds 3 and 4 was carried out by Jones
oxidation [15]. During the reaction of 1 with lithium acety-
lide [16] cleavage of the acetyl group occurred and led to the
formation of 5 in 80% yield. Acetylation of 5 gave the 3,28-di-
pathway. Thus,
a direct interaction between BA and
´
Correspondence: Prof. Dr. Rene Csuk, Bereich Organische Chemie,
Martin-Luther-Universitat Halle-Wittenberg, Kurt-Mothes-Str. 2, D-06120
¨
Halle (Saale), Germany.
E-mail: rene.csuk@chemie.uni-halle.de
Fax: þ49 (0) 345 5527030
ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

38
R. Csuk et al.
Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
sodium methoxide in methanol yielded deprotected 14 and
15 [23]. In a similar way, 5 gave a 85% yield of 16 whose
deacetylation yielded 93% of 17. Jones oxidation (70%) or
Swern oxidation (73%) of 16 again gave 12. The reaction of
compound 7 with DIMCARB (Scheme 3) [24] in ethanol led to
the formation of the enamine 18 [25].
All values are derived from dose-response curves obtained
by measuring the percentage of viable cells relative to
untreated controls after 96 h exposure of the test compounds
to the cell line using an SRB-assay for melanoma (518A2),
cervic cancer (A431), head and neck tumor (A253, FADU),
lung carcinoma (A549), ovarian cancer (A2780), colon cancer
(DLD-1, HCT-8, HCT-116, HT-29, SW-480), anaplastic thyroid
cancer (8505c, SW-1736), mamma carcinoma (MCF-7) and
liposarcoma. Values are the average from at least three inde-
pendent experiments. Variation was generally ꢀ10%;
NA ¼ no inhibition of cell growth at the highest concen-
tration (30 mM).
Figure 1. Structure of betulin and betulinic acid.
O-acetyl derivative 6. Oxidation of 5 yielded the 28-ethynyl-
lup-20(29)-en-3,28-dione 7. This compound was an ideal start-
ing material for further derivatization (Scheme 2). The reac-
tion of 7 with diazomethane [17] or ethyl diazoacetate [18]
yielded the corresponding pyrazoles 8 and 9, respectively; the
orientation of this addition follows the rule of von Auwers
and Ungemach [19]. Similarly, azides reacted with compound
7 to form triazoles. The 1,3-dipolar cycloadditions of ethyl
azidoacetate or 4-azidobenzoic acid with 7 were performed in
THF in the presence of catalytic amounts of copper(I) iodide
[20] to afford compounds 10 and 11, respectively.
The compounds were screened for their antitumor activity
in a panel of 15 human cancer cell lines in 96 well plates
using the colorimetric [26] sulforhodamine B (SRB) protocol.
The IC50 values of compounds 3–18 are reported in Table 1;
they were derived from the corresponding dose-response
curves. The 28-ethynyl-betulin derivatives 3, 4, and 7 showed
a higher cytotoxicity compared to parent betulinic acid. An
influence of the substituent at position C-3 can be deduced
from these data: Derivatives bearing an acetyl- or methyl-
moiety showed lower IC50 values than compounds possessing
Likewise, 2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl azide or
2,3,4,6-tetra-O-acetyl-b-D-mannopyranosyl azide [21, 22] gave
the triazoles 12 and 13, respectively. Their treatment with
Scheme 1. Synthesis of ethynyl derivatives: a) ethynyl magnesium bromide, THF, –788C, 1 h; b) CrO3, H2SO4, acetone, 08C, 30 min;
(c) lithium acetylide ethylenediamine complex, THF, –788C, 1 h; d) Ac2O, NEt3, 248C, 72 h.
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Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
New Betulin Derivatives
39
Scheme 2. 1,3-Dipolar cycloadditions: a) CH2N2, ether, 08C, 10 min; b) ethyl diazoacetate, toluene, reflux, 48 h; c) ethyl azidoacetate,
CuI, THF, 608C, 72 h; d) 4-azidobenzoic acid, CuI, THF, 608C, 72 h; e) 2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl azide (for 12 and 16) or
2,3,4,6-tetra-O-acetyl-b-D-mannopyranosyl azide (for 13), CuI, THF, 608C, 72 h; f) THF, MeOH, MeONa, 248C, 12–24 h.
a OH-C(3); the 3-oxo compound 7 is highly cytotoxic (IC50
-
growth was observed for compounds 12–17 even at the high-
est administrated concentration of 30 mM. Compound 18
shows IC50 values ¼ 2.7–5.8 mM, hence being more cytotoxic
than betulinic acid.
values 0.16–3.7 mM). For the pyrazole derivative 8 and 9 a
noteworthy activity was observed only for the colon cancer
cell line SW480 (IC50 ¼ 8.6 and 5.2 mM, respectively).
Similarly, the triazole 10 showed a low IC50 of 3.6 mM only
for mamma carcinoma cells (MCF-7). In contrast, the triazole
derivative 11, bearing a 4-carboxyphenyl substituent, showed
quite promising results for all cell lines. The presence of a
sugar moiety seems to decrease activity; no inhibition of cell
Betulinic acid and related compounds possess only a poor
solubility in water, hence making drug administration in vivo
difficult. To overcome this limitation, we studied the possi-
bility of encapsulation applying commercially available li-
posome formulations. In addition, liposomes are an effective
delivering system to mitochondria [27] playing a key role in
betulinic acid induced apoptosis. Good encapsulation was
achieved for the lead structure 7 using soybean lecithin
(Lipoid S75). Subsequent extrusion through a polycarbonate
membrane [28] with a pore size of 100 nm by a LiposoFast
system gave liposomes with a hydrodynamic diameter of 60–
120 nm (Z-average 102.0 nm), as determined by dynamic
light scattering. The encapsulation efficiency was about
60% as determined by HPLC and the physical stability of
the liposomes exceeded several weeks. Evaluation of the
Scheme 3. Synthesis of 18: (a) DIMCARB, EtOH, 248C, 24 h,
97%.
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40
R. Csuk et al.
Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
Table 1. Cytoxicity of the compounds in a panel of various human cancer cell lines.
Cell line
BA
3
4
7
8
9
10
11
12–17
18
518A2
A431
A253
FADU
A549
A2780
DLD-1
HCT-8
HCT-116
HT-29
SW480
8505C
SW1736
MCF-7
Lipo
11.9
15.4
11.1
10.4
14.9
11.0
17.5
17.8
13.3
16.1
6.4
2.9
7.5
1.7
12.8
2.7
0.55
7.2
12.5
11.8
1.4
6.9
5.3
0.62
13.7
6.8
2.6
7.6
1.4
20.5
3.8
0.58
10.0
16.5
18.7
1.3
7.9
5.3
0.54
18.5
10.3
0.17
0.91
0.16
2.7
0.35
0.18
1.9
3.7
1.2
0.23
0.78
1.7
20.4
16.2
14.8
19.8
20.5
12.5
26.4
15.0
20.1
15.7
8.6
23.1
12.3
14.0
15.9
16.1
6.6
24.1
12.8
15.2
12.7
5.2
9.2
12.7
10.3
25.0
22.9
14.5
12.4
10.0
18.8
21.5
12.9
18.0
29.6
3.6
9.6
3.9
9.2
3.8
6.9
6.7
4.7
2.5
3.6
5.4
10.4
9.6
8.5
5.5
10.9
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
4.3
4.7
4.2
3.0
5.8
2.7
3.8
4.8
3.4
3.6
4.8
4.4
2.9
3.8
4.2
6.7
14.1
19.3
13.4
18.6
14.3
11.4
9.8
11.6
14.9
9.7
0.16
3.3
1.7
19.2
19.5
liposomal formulation of compound 7 in the SRB assay
revealed the beneficial effect of encapsulation for several cell
lines (Table 2).
In summary, betulin derivatives bearing an ethynyl side
chain were synthesized and shown to possess quite promis-
ing antitumor activity by triggering apoptosis. To overcome
the drawback of a limited solubility in aqueous systems,
these compounds can be administered encapsulated in
liposomes.
Comparison of the calculated IC50-values derived from
dose-response curves of compound 7 (solution in DMSO)
and as aqueous liposomal formulation.
Additional experiments were performed to proof apopto-
sis. Thus, the floating cells collected after treatment with the Experimental
compounds 7 or 18 (applying IC90-concentrations for 24 h)
were analyzed by a trypan-blue dye exclusion test and DNA
gel electrophoresis (Fig. 2). Apoptotic cells possess an intact
cell membrane and can exclude the dye whereas necrotic
cells are stained blue. During the process of apoptosis the
action of endonucleases leads to DNA fragmentation. These
fragments can be detected in gel electrophoresis as ladders
[29–31].
General
Melting points are uncorrected (Leica hot stage microscope),
NMR spectra were recorded using the Varian spectrometers
Gemini 200, Gemini 2000 or Unity 500 (d given in ppm, J in
Hz, internal Me4Si), optical rotations were obtained using a
Perkin-Elmer 341 polarimeter (1 cm micro cell), IR spectra
(film or KBr pellet) on a Perkin-Elmer FT-IR spectrometer
Spectrum 1000, MS spectra were taken on a Intectra
GmbH AMD 402 (electron impact, 70 eV) or on a Finnigan
MAT TSQ 7000 (electrospray, voltage 4.5 kV, sheath gas nitro-
gen) instrument. TLC was performed on silica gel (Merck
5554). Spots were detected by spraying a solution of
ammonium molybdate and cerium(IV) sulfate in sulfuric
acid, followed by gently heating. The solvents were dried
according to usual procedures.
Table 2. IC50 values of compound 7.
Cell line 7 in DMSO
7 encapsulated
518A2
A431
A253
FADU
A549
A2780
DLD-1
HCT-8
HCT-116
HT-29
SW480
8505C
SW1736
MCF-7
Lipo
0.17
0.91
0.16
2.7
0.35
0.18
1.9
3.7
1.2
0.23
0.78
1.7
0.87
1.2
0.23
1.5
0.28
0.26
1.4
1.6
1.2
0.28
0.30
1.5
0.27
1.5
Cell lines and culture conditions
The cell lines 518A2, 8505C, A253, A2780, A431, A549, DLD-1,
FaDu, HCT-116, HCT-8, HT-29, LIPO, MCF-7, SW1736, and
SW480 were included in this study. Cultures were main-
tained as monolayer in RPMI 1640 (PAA Laboratories,
Pasching, Germany) supplemented with 10% heat inactivated
fetal bovine serum (Biochrom AG, Berlin, Germany) and
penicillin/streptomycin (PAA Laboratories) at 378C in a
humidified atmosphere of 5% CO2/95% air.
0.16
3.3
1.7
1.4
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Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
New Betulin Derivatives
41
Figure 2. Analysis of floating cells after treatment with IC90-concentrations for 24 h; trypan-blue exclusion test of compound 7 (left) for head
and neck tumor cell lineA253 and compound 18 (right) for colon cancer cell line SW480. DNA laddering of compound 7 (left) and compound 18
(right) for colon cancer cell line SW480.
Cytotoxicity assay
The solution obtained was extruded through a polycarbonate
filter of 100 nm pore size. Twenty-one cycles were applied
and concentration of the compound was determined by HPLC
(RP18, 4.6 ꢁ 250 mm, l ¼ 230 nm, methanol, 1.3 mL).
Liposomes were characterized by DLS.
The cytotoxicity of the compounds was evaluated using the
sulforhodamine-B (SRB) (Sigma Aldrich) microculture colori-
metric assay [26]. In short, exponentially growing cells were
seeded into 96-well plates on day 0 at the appropriate cell
densities to prevent confluence of the cells during the period
of experiment. After 24 h, the cells were treated with serial
dilutions of the compounds (0–30 mM) for 96 h. The final
concentration of DMSO or DMF solvent never exceeded 0.5%,
which was non-toxic to the cells. The percentages of surviving
cells relative to untreated controls were determined 96 h
after the beginning of drug exposure. After a 96 h treatment,
the supernatant medium from the 96 well plates was thrown
away and the cells were fixed with 10% TCA. For a thorough
fixation, the plates were allowed to rest at 48C. After fixation,
the cells were washed in a strip washer. The washing was
done four times with water using alternate dispensing and
aspiration procedures. The plates were then dyed with
100 mL of 0.4% SRB (sulforhodamine B) for about 20 min.
After dying the plates were washed with 1% acetic acid to
remove the excess of the dye and allowed to air dry overnight.
100 mL of 10 mM Tris base solution were added to each well
and absorbance was measured at 570 nm (using a 96 well
plate reader, Tecan Spectra, Crailsheim, Germany). The IC50
was estimated from the semi-logarithmic dose-response
curves.
Apoptosis test: Dye exclusion test
Apoptotic cell death was analyzed by trypan-blue dye (Sigma
Aldrich, Germany) on A431 and A2780 cell lines. The cell
culture flasks with 70–80% confluence were treated with IC90
doses of the compounds for 24 h. The supernatant medium
with floating cells was collected after treatment and centri-
fuged to collect dead and apoptotic cells. This pellet was re-
suspended in serum free media. Equal amounts of cell sus-
pension and trypan-blue were mixed and analyzed under a
microscope. Viable cells exclude the dye and appear colorless
whereas cells whose cell membrane is destroyed are stained
in blue color. If there are more colorless cells than stained
cells, then death of the cells can be characterized as
apoptotic.
Apoptosis test: DNA fragmentation assay
Determination of apoptotic cell death was performed by DNA
gel electrophoresis. Briefly, cell lines were treated with
respective IC90 doses of the compounds for 24 h. Floating
cells – as induced by drug exposure – were collected, re-
suspended in HBSS (1 mL) and transferred to 70% ethanol
(10 mL). The cells were collected and treated with PCB (40 mL,
96 parts of 0.2 M Na2HPO4 and 4 parts of 0.1 M citric acid (pH
7.8)) for 1 h at room temperature. The supernatant was col-
lected and treated with RNAse A (3 mL, 1mg/ml) and Nonide
NP40 (3 mL 0.25% in H2O) at 378C for 30 min. Then, protein-
ase K (3 mL, 1 mg/mL) was added and incubated for 30 min at
378C. DNA laddering was observed by running the samples on
2% agarose gel followed by ethidium bromide (Sigma Aldrich)
staining.
Preparation of liposomes
Unilamellar liposomes of approximately 100 nm diameter
were obtained by the method of Olson [28] employing a
laboratory extruder (LiposoFast, Avestin Inc.). In a typical
experiment for preparing 5 mL dispersion of liposomes,
5 mg of the compound were mixed with an excess
(125 mg) of phosphatidylcholine formulation (Lipoid S75)
in chloroform (5 mL) and evaporated to a film. The lipid film
was hydrated with H2O (5 mL) for 24 h at room temperature.
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R. Csuk et al.
Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
General procedure for the synthesis of substituted 28-
ethynyl-betulins (GP1)
(500 MHz, CDCl3): d ¼ 4.71 (d, 1H, J ¼ 2.1 Hz, CHa (30)),
4.58 (dd, 1H, J ¼ 2.1, 1.5 Hz, CHb (30)), 4.44 (dd, 1H,
ꢂ
A
solution of the corresponding betulinic aldehyde
J ¼ 10.4, 5.8 Hz, CHOAc (3)), 3.06 (s, 1H, HCꢂC), 2.92 (ddd,
ꢂ
(1.03 mmol) was cooled to –788C, then a solution of ethynyl-
magnesium bromide (4 mL, 2.0 mmol, 0.5 M in THF) was
added. After 1 h at –788C, the reaction was quenched by
the addition of brine (100 mL). The phases were separated
and the aq. layer was extracted with ethyl acetate
(2 ꢁ 50 mL). The combined extracts were dried over
Na2SO4 and evaporated to dryness. The residue was subjected
to column chromatography (silica gel, hexane/ethyl acetate,
8:2) to yield the corresponding 28-ethynyl-betulin as a dia-
stereomeric mixture.
1H, J ¼ 11.2, 11.2, 5.8 Hz, CH (19)), 2.47 (ddd, 1H, J ¼ 13.5, 3.3,
3.3 Hz, CHa (16)), 2.24 (ddd, 1H, J ¼ 12.7, 12.7, 3.8 Hz, CH (13)),
2.03 (dd, 1H, J ¼ 10.7, 8.5 Hz, CHa (22)), 2.02 (s, 3H, Ac), 1.81–
1.58 (m, 5H, CHa (21) þ CHa (12) þ CHa (1) þ CH (18) þ CHa
(2)), 1.65 (s, 3H, CH3 (29)), 1.56–1.17 (m, 12H, CHb (16) þ CH2
(6) þ CHb (22) þ CH2 (11) þ CHb (21) þ CH2 (15) þ CH2
(7) þ CH (9)), 0.98–0.88 (m, 2H, CHb (12) þ CHb (1)), 0.94 (s,
3H, CH3 (27)), 0.89 (s, 3H, CH3 (25)), 0.86–0.78 (m, 1H), 0.83 (s,
3H, CH3 (24)), 0.82 (s, 3H, CH3 (26)), 0.81 (s, 3H, CH3 (23)), 0.75
(d, 1H, J ¼ 9.1 Hz, CH (5)) ppm; 13C-NMR (125 MHz, CDCl3):
–
–
–
–
d ¼ 191.6 (C O), 170.9 (C O), 150.2 (C20, C CH ), 109.8 (C30,
–
–
2
ꢂ ꢂ
CH2 C), 80.9 (C3, CH), 80.5 (C31, CꢂC), 77.0 (C32, HCꢂC), 61.8
ꢂ ꢂ
–
–
General procedure for Jones oxidation (GP2)
To a stirred solution of the corresponding 28-ethinyl-betulin
(1.84 mmol) in acetone (10 mL) at 08C dropwise a solution of
chromium(VI) oxide (300 mg) in aq. H2SO4 (35%, 1 mL) was
added. After TLC revealed the absence of starting material,
the excess chromium(VI) oxide was destroyed by the addition
of 2-propanol (2 mL). The solution was concentrated in vacuo
and the residue partitioned between H2O (30 mL) and CH2Cl2
(30 mL). The layers were separated and the aqueous layer was
extracted with CH2Cl2 (10 mL). The combined organic
extracts were dried over Na2SO4, evaporated to dryness
and purified by column chromatography (silica gel, hex-
ane/ethyl acetate, 9:1).
(C17, Cquart.), 55.4 (C5, CH), 50.5 (C9, CH), 48.5 (C18, CH), 46.3
(C19, CH), 42.4 (C14, Cquart.), 40.7 (C8, Cquart.), 38.4 (C1, CH2),
37.8 (C4, Cquart.), 37.1 (C13, CH), 37.0 (C10, Cquart.), 35.5 (C22,
CH2), 34.2 (C7, CH2), 31.6 (C16, CH2), 29.7 (C21, CH2), 29.5 (C15,
CH2), 27.9 (C23, CH3), 25.5 (C12, CH2), 23.7 (C2, CH2), 21.3 (Ac),
20.8 (C11, CH2), 19.2 (C29, CH3), 18.1 (C6, CH2), 16.4 (C24, CH3),
16.2 (C26, CH3), 15.9 (C25, CH3), 14.3 (C27, CH3) ppm; MS (ESI,
MeOH): m/z ¼ 529.4 (30%, [M þ Na]þ), 1013.8 (100%,
[2 M þ Hþ); anal. calcd. for C34H50O3 (506.76) C, 80.58; H,
9.94; found: C, 80.49; H, 9.98.
3-O-Methyl-28-ethinyl-28-oxolup-20(29)-en-3-ol (4)
Compound 4 (0.44 g, 84%) was obtained from 3-O-methylbetu-
linic aldehyde (2) (0.50 g, 1.10 mmol) following GP1 and GP2 as
General procedure for the click reaction (GP3)
20
A solution of compound 7 (0.20 g, 0.43 mmol), the corre-
sponding azide (0.6 mmol) and copper(I) iodide (40 mg,
0.2 mmol) in THF (12 mL) was stirred at 608C for 72 h.
When TLC revealed the absence of starting material, the
solution was filtered and concentrated in vacuo. The residue
was subjected to column chromatography (silica gel, hexane/
ethyl acetate, 7:3).
a colorless solid; mp 176–1798C; [a]D ¼ 26.68 (c ¼ 3.8, CHCl3);
Rf ¼ 0.76 (silica gel, hexane/ethyl acetate, 9:1); IR (KBr):
n ¼ 3297 w, 3202 w, 2944 s, 2869 m, 2080 m, 1674 s,
1453 m, 1378 m, 1358 w, 1246 w, 1182 w, 1097 m,
1050 m cmꢂ1
;
1H-NMR (500 MHz, CDCl3): d ¼ 4.70 (d, 1H,
J ¼ 2.1 Hz, CHa (30)), 4.58 (dd, 1H, J ¼ 2.1, 1.5 Hz, CHb (30)),
ꢂ
3.32 (s, 1H, OCH3), 3.06 (s, 1H, HCꢂC), 2.91 (ddd, 1H, J ¼ 11.2,
ꢂ
11.2, 5.8 Hz, CH (19)), 2.60 (dd, 1H, J ¼ 11.6, 4.6 Hz, CHOCH3
(3)), 2.45 (ddd, 1H, J ¼ 13.5, 3.3, 3.3 Hz, CHa (16)), 2.24 (ddd, 1H,
J ¼ 12.7, 12.7, 3.8 Hz, CH (13)), 2.02 (dd, 1H, J ¼ 10.7, 8.5 Hz,
CHa (22)), 1.82–1.60 (m, 5H, CHa (21) þ CHa (2) þ CHa
(12) þ CHa (1) þ CH (18)), 1.65 (s, 3H, CH3 (29)), 1.56–1.30 (m,
13H, CHb (16) þ CH2 (6) þ CHb (22) þ CHa (11) þ CHb
(21) þ CHa (15) þ CHb (2) þ CH2 (7)), 1.27–1.17 (m, 13H, CHb
(15) þ CHb (11) þ CH (9)), 0.98–0.88 (m, 1H, CHb (12)), 0.94 (s,
3H, CH3 (27)), 0.92 (s, 3H, CH3 (23)), 0.89 (s, 3H, CH3 (25)), 0.86–
0.78 (m, 1H, CHb (1)), 0.80 (s, 3H, CH3 (24)), 0.70 (s, 3H, CH3 (26)),
0.65 (d, 1H, J ¼ 9.1 Hz, CH (5)) ppm; 13C-NMR (125 MHz, CDCl3):
General procedure for deacetylation (GP4)
A solution of compound 12 or 13 (150 mg, 0.18 mmol) in THF
(5 mL) and MeOH (5 mL) containing NaOMe (11 mg,
0.2 mmol) was stirred for 12 h, concentrated in vacuo and
the residue subjected to column chromatography (silica gel,
dichloromethane/methanol, 9:1).
3-O-Acetyl-28-ethinyl-28-oxolup-20(29)-en-3-ol (3)
Compound 3 (0.42 g, 73%) was obtained from 3-O-acetylbetu-
linic aldehyde (1) (0.50 g, 1.03 mmol) following GP1 and GP2
20
–
–
–
–
2
as a colorless solid; mp 198–2008C; [a]D ¼ 25.48 (c ¼ 3.0,
d ¼ 191.6 (C O), 150.3 (C20, C CH ), 109.7 (C30, CH C), 88.6
–
–
2
ꢂ ꢂ
(C3, CHOCH3), 80.5 (C31, CꢂC), 77.0 (C32, HCꢂC), 61.8 (C17,
ꢂ ꢂ
CHCl3); Rf ¼ 0.60 (silica gel, hexane/ethyl acetate, 9:1); IR
(KBr): n ¼ 3244 m, 3068 w, 2952 s, 2871 m, 2085 m,
1724 s, 1677 s, 1640 w, 1452 m, 1393 m, 1376 m, 1317 w,
Cquart.), 57.4 (OCH3), 55.9 (C5, CH), 50.6 (C9, CH), 48.2 (C18, CH),
46.3 (C19, CH), 42.4 (C14, Cquart.), 40.8 (C8, Cquart.), 38.8 (C1, CH2),
38.6 (C4, Cquart.), 37.2 (C10, Cquart.), 37.1 (C13, CH), 35.5 (C22,
1250 s, 1105 w, 1087 w, 1064 m, 1028 s cmꢂ1 1H-NMR
;
ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
New Betulin Derivatives
43
CH2), 34.3 (C7, CH2), 31.2 (C21, CH2), 40.0 (C16, CH2), 29.5 (C15,
CH2), 28.0 (C23, CH3), 25.6 (C12, CH2), 22.2 (C2, CH2), 20.8 (C11,
CH2), 19.2 (C29, CH3), 18.2 (C6, CH2), 16.1 (C24, CH3), 16.1 (C26,
CH3), 15.9 (C25, CH3), 14.4 (C27, CH3) ppm; MS (ESI, MeOH): m/
z ¼ 501.0 (50%, [M þ Na]þ), 957.2 (100%, [2 M þ H]þ); anal.
calcd. for C33H50O2 (478.75): C, 82.79; H, 10.53; found: C,
81.76; H, 10.57.
CDCl3): d ¼ 5.88 (m, 1H, CHOH (28)), 4.61 (d, 1H, J ¼ 2.02 Hz,
CHa (30)), 4.56 (dd, 1H, J ¼ 2.0, 1.4 Hz, CHb (30)), 3.17 (dd, 1H,
J ¼ 5.0, 11.1 Hz, CHOH (3)), 2.87 (ddd, 1H, J ¼ 6.2, 11.0,
ꢂ
11.0 Hz, CH (19)), 2.47 (d, 1H, J ¼ 2.0 Hz, C ꢂ CH (32)), 2.01
ꢂ
(m, 1H, CHa (21)), 2.08 (ddd, 1H, J ¼ 1.2, 9.1, 11.1 Hz, CHa (16)),
1.98 (m, 1H, CHa (22)), 1.94 (dd, 1H, J ¼ 3.9, 8.2 Hz, CH (13)),
1.74 (m, 1H, CHa (12)), 1.66 (s, 3H, CH3 (29)), 1.64–1.49 (m, 7H,
CHa (6) þ CHa (11) þ CHb (12) þ CH2 (2) þ CH2 (13)), 1.45–
1.30 (m, 6H, CHb (6) þ CHb (22) þ CH2 (7) þ CH (18) þ CH
(9)), 1.29–1.10 (m, 5H, CHb (11) þ CHb (16) þ CH2 (15), CHb
(21)), 1.02 (s, 3H, CH3 (27)), 0.99 (s, 3H, CH3 (25)), 0.89 (ddd, 1H,
J ¼ 4.5, 12.6, 12.6 Hz, CHb (1)), 0.95 (s, 3H, CH3 (24)), 0.81 (s,
28-Ethinyl-betulin (5)
In analogy to GP1, from 3-O-acetylbetulinic aldehyde (1) (2 g,
4.1 mmol) and the lithium acetylide ethylenediamine com-
plex (1.5 g, 16.4 mmol) compound 13 (1.52 g, 80%) was
obtained as a colorless solid after purification by column
chromatography (silica gel, CHCl3/Et2O, 95:5); mp 173–
3H, CH3 (26)), 0.74 (s, 3H, CH3 (23)), 0.67 (d, 1H, J ¼ 9.2 Hz, (5))
13
–
ppm; C-NMR (125 MHz, CDCl ): d ¼ 170.9 (C O), 169.6
–
3
20
– –
(C O), 150.4 (C20, C CH ), 109.8 (C30, CH C), 81.0 (C31,
– –
2
–
–
2
1788C; [a]D ¼ –14.68 (c ¼ 5.9, CHCl3); Rf ¼ 0.32 (silica gel,
ꢂ ꢂ
CꢂCH) 76.7 (C3, CH), 74.2 (C32, HCꢂC), 66.7 (C28, CH), 55.5
ꢂ ꢂ
CHCl3/Et2O, 95:5); IR (KBr): n ¼ 3421 s, 2941 s, 2871 s,
2120 m, 1757 s, 1639 m, 1454 s, 1375 s, 1225 s, 1040 s cmꢂ1
;
(C5, CH), 50.3 (C17, Cquart), 50.2 (C9, CH), 49.2 (C18, CH),48.8
(C19, CH), 43.1 (C14, Cquart), 41.0 (C8, Cquart), 38.5 (C4, Cquart),
37.9 (C1, CH2), 37.5 (C13, CH), 37.2 (C10, Cquart.), 34.7 (C7, CH2),
34.3 (C21, CH2), 34.1 (C16, CH2), 32.4 (C22, CH2), 28.0 (C23,
CH3), 27.8 (C15, CH2), 25.2 (C12, CH2), 23.8 (C2, CH2), 21.6 (Ac),
21.5 (Ac), 20.9 (C11, CH2), 18.8 (C29, CH3), 18.2 (C6, CH2), 16.5
(C24, CH3), 16.2 (C26 þ C25, 2 CH3), 15.1 (C27, CH3) ppm;
MS (ESI, MeOH): m/z ¼ 551.2 (10%, [M þ H]þ), 573.3 (30%,
[M þ Na]þ), 1123.2 (100%, [2 M þ Na]þ); anal. calcd. for
1H-NMR (500 MHz, CDCl3): d ¼ 4.88 (m, 1H, CHOH (28)), 4.70
(d, 1H, J ¼ 2.02 Hz, CHa (30)), 4.55 (dd, 1H, J ¼ 2.0, 1.4 Hz, CHb
(30)), 3.17 (dd, 1H, J ¼ 5.0, 11.1 Hz, CHOH (3)), 2.87 (ddd, 1H,
ꢂ
J ¼ 6.2, 11.0, 11.0 Hz, CH (19)), 2.47 (d, 1H, J ¼ 2.0 Hz, C ꢂ CH
ꢂ
(32)), 2.01 (m, 1H, CHa (21)), 2.08 (ddd, 1H, J ¼ 1.2, 9.1, 11.1 Hz,
CHa (16)), 1.98 (m, 1H, CHa (22)), 1.94 (dd, 1H, J ¼ 3.9, 8.2 Hz,
CH (13)), 1.74 (m, 1H, CHa (12)), 1.66 (s, 3H, CH3 (29)), 1.64–1.49
(m, 7H, CHa (6) þ CHa (11) þ CHb (12) þ CH2 (2) þ CH2 (13)),
1.45–1.30 (m, 6H, CHb (6) þ CHb (22) þ CH2 (7) þ CH
(18) þ CH (9)), 1.29–1.10 (m, 5H, CHb (11) þ CHb (16) þ CH2
(15), CHb (21)), 1.02 (s, 3H, CH3 (27)), 0.99 (s, 3H, CH3 (25)), 0.89
(ddd, 1H, J ¼ 4.5, 12.6, 12.6 Hz, CHb (1)), 0.95 (s, 3H, CH3 (24)),
0.81 (s, 3H, CH3 (26)), 0.74 (s, 3H, CH3 (23)), 0.67 (d, 1H,
C
36H54O4 (550.81): C, 78.50; H, 9.88; found: C, 78.37; H, 10.02.
28-Ethinyl-lup-20(29)-en-3,28-dione (7)
Compound 7 (0.44 g, 84%) was obtained from 3-O-acetylbetu-
linic aldehyde (1) (0.50 g, 1.03 mmol) and lithium acetylide
ethylenediamine complex (0.38 g, 4.12 mmol) following GP1
J ¼ 9.2 Hz, (5)) ppm; 13C-NMR (125 MHz, CDCl3): d ¼ 151.0
20
ꢂ
–
–
–
(C20, C CH ), 109.6 (C30, CH C), 84.7 (C31, CꢂCH) 78.9
and GP2 as a colorless solid; mp 2148C; [a]D ¼ 45.88 (c ¼ 5.0,
–
2
2
ꢂ
ꢂ
(C3, CHOH), 74.2 (C32, HCꢂC), 66.0 (C28, CHOH), 55.3 (C5,
CHCl3); Rf ¼ 0.38 (silica gel, hexane/ethyl acetate, 9:1); IR (KBr):
n ¼ 3206 m, 3070 w, 2945 s, 2868 m, 2085 m, 1702 s, 1670 s,
1641 m, 1455 m, 1390 m, 1378 m, 1349 w, 1137 w, 1107 w,
ꢂ
CH), 50.6 (C17, Cquart), 50.3 (C9, CH), 49.0 (C18, CH), 48.6 (C19,
CH), 43.0 (C14, Cquart), 40.9 (C8, Cquart), 38.9 (C4, Cquart), 38.7 (C1,
CH2), 37.3 (C13, CH), 37.1 (C10, Cquart.), 34.3 (C7, CH2), 34.2 (C21,
CH2), 33.9 (C16, CH2), 32.4 (C22, CH2), 28.0 (C23, CH3), 27.9 (C15,
CH2), 27.4 (C2, CH2), 25.1 (C12, CH2), 20.8 (C11, CH2), 18.8 (C29,
CH3), 18.3 (C6, CH2), 16.1 (C24, CH3), 16.1 (C26, CH3), 15.3 (C25,
CH3), 15.1 (C27, CH3) ppm; MS (ESI, MeOH): m/z ¼ 467.4 (60%,
[M þ H]þ); anal. calcd. for C32H50O2 (466.74): C, 82.35; H,
10.78; found: C, 82.04; H, 10.99.
1084 w, 1062 m, 1027 m, 1004 w cmꢂ1 1H-NMR (500 MHz,
;
CDCl3): d ¼ 4.59 (d, 1H, J ¼ 2.1 Hz, CHa (30)), 4.46 (dd, 1H,
ꢂ
J ¼ 2.1, 1.5 Hz, CHb (30)), 3.18 (s, 1H, HCꢂC), 2.79 (ddd, 1H,
ꢂ
J ¼ 11.2, 11.0, 4.9 Hz, CH (19)), 2.40–2.30 (m, 2H, CHa
(16) þ CHa (2)), 2.28–2.22 (m, 1H, CHb (2)), 2.16 (ddd, 1H,
J ¼ 12.8, 11.6, 3.8 Hz, CH (13)), 1.93 (dd, 1H, J ¼ 12.9,
8.4 Hz, CHa (22)), 1.76 (ddd, 1H, J ¼ 13.1, 7.6, 4.5 Hz, CH (1)),
1.69–1.50 (m, 3H, CHa (21) þ CHa (12) þ CH (18)), 1.54 (s,
3H, CH3 (29)), 1.42 (ddd, 1H, J ¼ 13.7, 13.7, 3.8 Hz, CHb (16)),
1.37–1.08 (m, 12H, CH2 (6) þ CHb (22) þ CH2 (7) þ CHb
(21) þ CH2 (11) þ CHb (1) þ CH (9) þ CHa (15) þ CH (5)),
0.95–0.83 (m, 1H, CHb (12)), 0.92 (s, 3H, CH3 (23)), 0.88 (s,
3H, CH3 (24)), 0.83 (s, 3H, CH3 (27)), 0.81 (s, 3H, CH3 (25)),
0.79 (s, 3H, CH3 (26)) ppm; 13C-NMR (125 MHz, CDCl3):
3,28-O-Diacetyl-28-ethinyl-betulin (6)
Acetylation of compound 5 (120 mg, 0.25 mmol with Ac2O
and triethylamine (100 mL, 0.72 mmol) for 72 h at 248C fol-
lowed by usual aqueous work-up and chromatography (silica
gel, CHCl3/Et2O, 95:5) gave 6 (128 mg, 93%) as a colorless
20
solid; mp 108–113 8C; [a]D ¼ 1.98 (c ¼ 5.4, CHCl3);
–
–
–
–
Rf ¼ 0.93 (silica gel, CHCl3/Et2O, 95/5); IR (KBr):
n ¼ 3448 m, 3309 m, 2962 s, 1734 s, 1640 m, 1456 w,
d ¼ 217.6 (C O), 191.4 (C O), 149.8 (C20, C CH ), 109.5 (C30,
–
–
2
ꢂ
ꢂ
ꢂ
–
–
CH2 C), 80.1 (C31, CꢂC), 77.3 (C32, HCꢂC), 61.4 (C17, Cquart.),
ꢂ
1375 m, 1261 s, 1106 m, 1021 m cmꢂ1
;
1H-NMR (500 MHz,
54.6 (C5, CH), 49.6 (C9, CH), 48.1 (C18, CH), 46.9 (C4, Cquart.), 46.0
ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

44
R. Csuk et al.
Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
(C19, CH), 42.4 (C14, Cquart.), 40.3 (C8, Cquart.), 39.3 (C1, CH2), 36.9
(C13, CH), 36.5 (C10, Cquart.), 35.1 (C22, CH2), 33.8 (C2, CH2), 33.2
(C7, CH2), 31.2 (C16, CH2), 29.7 (C21, CH2), 29.1 (C15, CH2), 26.3
(C23, CH3), 25.2 (C12, CH2), 21.1 (C11, CH2), 20.7 (C24, CH3), 19.3
(C6, CH2), 18.9 (C29, CH3), 15.6 (C26, CH3), 15.4 (C25, CH3), 14.0
(C27, CH3) ppm; MS (ESI, MeOH): m/z ¼ 463.3 (100%, [M þ H]þ);
anal. calcd. for C32H46O2 (462.71): C, 83.06; H, 10.02; found: C,
83.24; H, 10.06.
heated under reflux for 24 h. After TLC revealed the absence
of starting material, the reaction mixture was concentrated
in vacuo and the residue subjected to column chromatog-
raphy (silica gel, hexane/ethyl acetate, 8:2). Compound 9
(0.20 g, 81%) was obtained as a colorless solid; mp 154–
20
1578C; [a]D ¼ 32.38 (c ¼ 4.5, CHCl3); Rf ¼ 0.35 (silica gel,
hexane/ethyl acetate, 8:2); IR (KBr): n ¼ 3274 br, 3072 w,
2945 s, 2868 m, 1706 s, 1672 s, 1642 m, 1560 w, 1460 m,
1383 m, 1307 m, 1226 s, 1116 m, 1025 m cmꢂ1 1H-NMR
;
28-(Pyrazol-3-yl)-3,28-dioxo-28-ethinyllup-20(29)-en (8)
An ethereal solution of diazomethane was added at 08C to a
solution of compound 7 (0.20 g, 0.43 mmol) in Et2O (10 mL)
until no further consumption of the diazomethane was
observed. After stirring for additional 10 min, the excess
of diazomethane was destroyed with acetic acid (5%) and
the reaction mixture was concentrated in vacuo. After column
chromatography compound 8 (0.20 g, 94%) was obtained as a
(500 MHz, CDCl3): d ¼ 11.56 (br s, 1H, NH), 7.27 (br s, 1H,
CH (pyrazole)), 4.73 (d, 1H, J ¼ 2.1 Hz, CHa (30)), 4.60 (br s, 1H,
CHb (30)), 4.40 (q, 2H, J ¼ 7.0 Hz, OCH2), 2.94 (ddd, 1H,
J ¼ 11.0, 11.0, 4.6 Hz, CH (19)), 2.62 (ddd, 1H, J ¼ 12.7,
12.7, 5.0 Hz, CH (13)), 2.70 (ddd, 1H, J ¼ 13.8, 3.3, 3.3 Hz,
CHa (16)), 2.44 (dd, 1H, J ¼ 9.6, 7.6 Hz, CHa (2)), 2.40 (dd,
1H, J ¼ 7.6, 4.5 Hz, CHb (2)), 2.52-2.26 (m, 3H, CH2
(2) þ CHa (22)), 1.88 (ddd, 1H, J ¼ 12.3, 7.6, 4.5 Hz, CH (1)),
1.80–1.58 (m, 5H, CHa (12) þ CHb (16) þ CHa (21) þ CH
(18) þ CHb (22)), 1.69 (s, 3H, CH3 (29)), 1.45–1.23 (m, 10H,
CH2 (11) þ CH2 (6) þ CHb (21) þ CHb (1) þ CH2 (7) þ CH
(9) þ CH (5)), 1.39 (t, 3H, J ¼ 7.0 Hz, CH3), 1.22–1.08 (m, 2H,
CH2 (15)), 1.05–0.95 (m, 1H, CHb (12)), 1.03 (s, 3H, CH3 (23)),
0.98 (s, 3H, CH3 (24)), 0.97 (s, 3H, CH3 (27)), 0.90 (s, 3H, CH3
(25)), 0.89 (s, 3H, CH3 (26)) ppm; 13C-NMR (125 MHz, CDCl3):
20
colorless solid; mp 165–1678C; [a]D ¼ 25.18 (c ¼ 4.2, CHCl3);
Rf ¼ 0.29 (silica gel, hexane/ethyl acetate, 8:2); IR (KBr):
n ¼ 3262 s, 3147 w, 2938 s, 2865 s, 1698 s, 1653 s,
1460 m, 1416 m, 1378 m, 1349 w, 1319 m, 1281 s, 1258 w,
1116 m, 1059 m, 1023 w cmꢂ1 1H-NMR (500 MHz, CDCl3):
;
d ¼ 7.63 (br s, 1H, CH (pyrazole)), 6.79 (br s, 1H, CH (pyra-
zole)), 4.75 (d, 1H, J ¼ 2.1 Hz, CHa (30)), 4.60 (br s, 1H, CHb
(30)), 2.98 (ddd, 1H, J ¼ 11.0, 11.0, 4.6 Hz, CH (19)), 2.74–2.65
(m, 2H, CHa (16) þ CH (13)), 2.47 (dd, 1H, J ¼ 9.6, 7.6 Hz, CHa
(2)), 2.40 (dd, 1H, J ¼ 7.6, 4.5 Hz, CHb (2)), 2.33 (dd, 1H,
J ¼ 12.2, 7.1 Hz, CHa (22)), 1.89 (ddd, 1H, J ¼ 12.3, 7.6,
4.5 Hz, CH (1)), 1.81–1.59 (m, 5H, CHa (12) þ CHb
(16) þ CHa (21) þ CH (18) þ CHb (22)), 1.69 (s, 3H, CH3 (29)),
1.45–1.22 (m, 10H, CH2 (11) þ CH2 (6) þ CHb (21) þ CHb
(1) þ CH2 (7) þ CH (9) þ CH (5)), 1.22–1.08 (m, 2H, CH2
(15)), 1.05–0.95 (m, 1H, CHb (12)), 1.04 (s, 3H, CH3 (23)), 0.99
(s, 3H, CH3 (24)), 0.98 (s, 3H, CH3 (27)), 0.91 (s, 6H, CH3
(25) þ CH3 (26)) ppm; 13C-NMR (125 MHz, CDCl3): d ¼ 218.2
–
–
–
–
d ¼ 218.1 (C O), 197.1 (C O), 161.0 (C O), 150.3 (C20,
–
–
–
–
–
–
C CH ), 110.6 (pyrazole, CH), 109.7 (C30, CH C), 61.1
2
2
(OCH2), 60.2 (C17, Cquart.), 55.0 (C5, CH), 50.2 (C18, CH), 50.0
(C9, CH), 47.3 (C4, Cquart.), 45.6 (C19, CH), 42.4 (C14, Cquart.),
40.7 (C8, Cquart.), 39.6 (C1, CH2), 36.9 (C13, CH), 36.9 (C10,
C
quart.), 36.8 (C22, CH2), 34.1 (C2, CH2), 33.5 (C7, CH2), 32.8
(C16, CH2), 30.6 (C21, CH2), 29.6 (C15, CH2), 26.5 (C23, CH3),
25.6 (C12, CH2), 21.5 (C11, CH2), 21.0 (C24, CH3), 19.6 (C6, CH2),
19.3 (C29, CH3), 15.9 (C26, CH3), 15.8 (C25, CH3), 14.2 (C27,
CH3), 14.4 (CH3) ppm; MS (ESI, MeOH): m/z ¼ 577.3 (60%,
[M þ H]þ), 1175.1 (100%, [2 M þ Na]þ); anal. calcd. for
–
–
–
–
(C O), 197.4 (C O), 150.6 (C20, C CH ), 142.3 (pyrazole,
C36H52N2O4 (576.81): C, 74.96; H, 9.09; N, 4.86; found: C,
–
–
2
–
C
quart.), 136.4 (pyrazole, CH), 109.6 (C30, CH2 C), 108.1 (pyr-
74.56; H, 8.81; N, 4.75.
–
azole, CH), 60.1 (C17, Cquart.), 55.0 (C5, CH), 50.2 (C18, CH), 50.0
(C9, CH), 47.3 (C4, Cquart.), 45.6 (C19, CH), 42.4 (C14, Cquart.),
40.6 (C8, Cquart.), 39.6 (C1, CH2), 37.0 (C22, CH2), 36.9 (C13, CH),
36.9 (C10, Cquart.), 34.1 (C2, CH2), 33.5 (C7, CH2), 33.0 (C16, CH2),
30.6 (C21, CH2), 29.6 (C15, CH2), 26.6 (C23, CH3), 25.6 (C12,
CH2), 21.5 (C11, CH2), 21.0 (C24, CH3), 19.6 (C6, CH2), 19.3 (C29,
CH3), 16.0 (C26, CH3), 15.8 (C25, CH3), 14.5 (C27, CH3) ppm; MS
(ESI, MeOH): m/z ¼ 505.4 (90%, [M þ H]þ), 1009.3 (100%,
[2 M þ H]þ); anal. calcd. for C33H48N2O2 (504.75): C, 78.53;
H, 9.59; N, 5.55; found: C, 78.47; H, 9.59; N, 5.32.
28-(1-(Ethylcarboxymethyl)-1H-1,2,3-triazol-4-yl)-3,28-
dioxo-28-ethinyllup-20(29)-en (10)
Compound 10 (0.21 g, 83%) was obtained from compound 7
(0.20 g, 0.43 mmol) and ethyl azidoacetate (78 mg,
0.60 mmol) following GP3 as a colorless solid; mp 203–205
20
8C; [a]D ¼ 22.08 (c ¼ 5.0, CHCl3); Rf ¼ 0.23 (silica gel, hex-
ane/ethyl acetate, 8:2); IR (KBr): n ¼ 3147 w, 3071 w, 2946 s,
2869 s, 1757 s, 1704 s, 1672 s, 1642 w, 1518 m, 1461 s,
1376 s, 1214 s, 1176 s, 1139 w, 1024 s cmꢂ1
;
1H-NMR
(500 MHz, CDCl3): d ¼ 8.17 (s, 1H, CH (triazole)), 5.16 (s,
2H, NCH2), 4.73 (d, 1H, J ¼ 2.1 Hz, CHa (30)), 4.58 (dd, 1H,
J ¼ 2.1, 1.5 Hz, CHb (30)), 4.28 (q, 2H, J ¼ 7.0 Hz, OCH2), 3.13
(ddd, 1H, J ¼ 13.8, 3.3, 3.3 Hz, CHa (16)), 2.95 (ddd, 1H,
J ¼ 11.0, 11.0, 4.6 Hz, CH (19)), 2.63 (ddd, 1H, J ¼ 12.7,
28-(5-(Ethylcarboxy)-pyrazol-3-yl)-3,28-dioxo-28-
ethinyllup-20(29)-en (9)
A solution of compound 3 (0.20 g, 0.43 mmol) and ethyl
diazoacetate (0.12 g, 1.0 mmol) in toluene (10 mL) was
ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
New Betulin Derivatives
45
12.7, 5.0 Hz, CH (13)), 2.56 (dd, 1H, J ¼ 12.7, 7.1 Hz, CHa (22)),
2.44 (dd, 1H, J ¼ 9.6, 7.6 Hz, CHa (2)), 2.40 (dd, 1H, J ¼ 7.6,
4.5 Hz, CHb (2)), 1.88 (ddd, 1H, J ¼ 12.3, 7.6, 4.5 Hz, CH (1)),
1.82–1.55 (m, 5H, CHa (12) þ CHb (16) þ CHa (21) þ CH
(18) þ CHb (22)), 1.69 (s, 3H, CH3 (29)), 1.45–1.25 (m, 10H,
CH2 (11) þ CH2 (6) þ CHb (21) þ CH2 (7) þ CH (9) þ CHb
(1) þ CH (5)), 1.19–1.09 (m, 2H, CH2 (15)), 1.05–0.95 (m, 1H,
CHb (12)), 1.03 (s, 3H, CH3 (23)), 0.98 (s, 6H, CH3 (24) þ CH3
(27)), 0.91 (s, 3H, CH3 (25)), 0.90 (s, 3H, CH3 (26)) ppm; 13C-NMR
31.7 (C16, CH2), 30.6 (C21, CH2), 29.7 (C15, CH2), 26.6 (C23, CH3),
25.6 (C12, CH2), 21.5 (C11, CH2), 21.0 (C24, CH3), 19.6 (C6, CH2),
19.3 (C29, CH3), 16.0 (C26, CH3), 15.8 (C25, CH3), 14.1 (C27, CH3)
ppm; MS (ESI, MeOH): m/z ¼ 624.7 (100%, [M – H]–); anal. calcd.
for C39H51N3O4 (625.84): C, 74.85; H, 8.21; N, 6.71; found: C,
74.54; H, 8.43; N, 6.56.
28-[1-(2,3,4,6-Tetra-O-acetyl-b-D-glucopyranosyl)-1H-
1,2,3-triazol-4-yl]-lup-20(29)-en-3,28-dione (12)
From 7: Compound 12 (0.26 g, 72%) was obtained from com-
pound 7 (0.20 g, 0.43 mmol) and 2,3,4,6-tetra-O-acetyl-b-D-
glucopyranosyl azide (0.16 g, 0.43 mmol) following GP3 as
a colorless solid.
–
–
–
–
(125 MHz, CDCl ): d ¼ 218.0 (C O), 198.5 (C O), 165.6 (C O),
–
–
3
–
150.8 (C20, C CH ), 147.8 (triazole, Cquart.), 129.0 (triazole,
–
–
CH), 109.4 (C30, CH2 C), 62.6 (OCH ), 60.6 (C17, Cquart.), 54.9
2
–
(C5, CH), 50.8 (NCH2), 50.2 (C18, CH), 50.0 (C9, CH), 47.2 (C4,
2
C
quart.), 45.9 (C19, CH), 42.4 (C14, Cquart.), 40.7 (C8, Cquart.), 39.6
From 16: Compound 12 (70 mg, 70%) was obtained from
compound 16 (100 mg, 0.2 mmol) by Jones oxidation follow-
ing GP2.
(C1, CH2), 37.0 (C13, CH), 36.9 (C10, Cquart.), 36.1 (C22, CH2),
34.0 (C2, CH2), 33.5 (C7, CH2), 31.7 (C16, CH2), 30.6 (C21, CH2),
29.6 (C15, CH2), 26.6 (C23, CH3), 25.6 (C12, CH2), 21.5 (C11,
CH2), 20.9 (C24, CH3), 19.6 (C6, CH2), 19.3 (C29, CH3), 16.0 (C26,
CH3), 15.8 (C25, CH3), 14.7 (C27, CH3), 14.0 (Et, CH3) ppm; MS
(ESI, MeOH): m/z ¼ 592.4 (100%, [M þ H]þ), 614.3 (90%,
[M þ Na]þ), 1205.1 (80% [2 M þ Na]þ); anal. calcd. for
From 16: Compound 12 (290 mg, 73%) was obtained from
compound 16 (400 mg, 0.5 mmol) by Swern oxidation apply-
ing DMSO (165 mL, 2 mmol), oxalyl chloride (172 mL, 2 mmol)
and triethylamine (700 mL, 5 mmol) in dry dichloromethane
(5 mL) for 2 h at –408C and 12 h at 248C followed by chroma-
tography (silica gel, CHCl3/Et2O, 95:5); mp 174–1778C;
C
36H53N3O4 (591.82): C, 73.06; H, 9.03, N, 7.10; found: C,
20
72.74; H, 9.14, N, 7.72.
[a]D ¼ –15.18 (c ¼ 4.4, CHCl3); Rf ¼ 0.75 (silica gel, hexane/
ethyl acetate, 5:5); IR (KBr): n ¼ 2946 m, 2871 w, 1760 s, 1706
28-[1-(4-Carboxyphenyl)-1H-1,2,3-triazol-4-yl]-lup-20(29)-
en-3,28-dione (11)
w, 1676 m, 1521 w, 1460 m, 1376 m, 1221 s, 1108 m, 1066 m,
1
1036 m cmꢂ1; H-NMR (500 MHz, CDCl3): d ¼ 8.25 (s, 1H, CH
Compound 11 (0.20 g, 76%) was obtained from compound 7
(0.20 g, 0.43 mmol) and 4-azidobenzoic acid (98 mg,
0.60 mmol) following GP3 as a colorless solid; mp >2508C;
(triazole)), 5.87 (d, 1H, J ¼ 8.9 Hz, Glc CH (1)), 5.44–5.33 (m, 2H,
Glc CH (3) þ CH (2)), 5.22 (dd, 1H, J ¼ 10.1, 9.2 Hz, Glc CH (4)),
4.71 (d, 1H, J ¼ 2.1 Hz, CHa (30)), 4.56 (dd, 1H, J ¼ 2.1,
1.5 Hz, CHb (30)), 4.29 (dd, 1H, J ¼ 12.7, 4.8 Hz, Glc CHa (6)),
4.15 (dd, 1H, J ¼ 12.7, 2.0 Hz, Glc CHb (6)), 4.00 (ddd, 1H,
J ¼ 10.1, 4.8, 2.0 Hz, Glc CH (5)), 3.04 (ddd, 1H, J ¼ 13.8, 3.3,
3.3 Hz, CHa (16)), 2.90 (ddd, 1H, J ¼ 11.0, 11.0, 4.6 Hz, CH (19)),
2.63 (ddd, 1H, J ¼ 12.7, 12.7, 5.0 Hz, CH (13)), 2.50–2.29 (m,
3H, CHa (22) þ CH2 (2)), 2.06 (s, 3H, Ac), 2.03 (s, 3H, Ac), 1.99 (s,
3H, Ac), 1.88 (ddd, 1H, J ¼ 12.3, 7.6, 4.5 Hz, CH (1)), 1.85 (s, 3H,
Ac), 1.77–1.53 (m, 5H, CHa (12) þ CHb (16) þ CHa (21) þ CH
(18) þ CHb (22)), 1.66 (s, 3H, CH3 (29)), 1.43–1.25 (m, 10H, CH2
(11) þ CH2 (6) þ CH2 (7) þ CH (9) þ CHb (1) þ CHb (21) þ CH
(5)), 1.17–1.06 (m, 2H, CH2 (15)), 1.03–0.89 (m, 1H, CHb (12)), 1.00
(s, 3H, CH3 (23)), 0.96 (s, 6H, CH3 (24) þ CH3 (27)), 0.89 (s,
3H, CH3 (25)), 0.88 (s, 3H, CH3 (26)) ppm; 13C-NMR (125 MHz,
20
[a]D ¼ 9.48 (c ¼ 3.3, CHCl3); Rf ¼ 0.19 (silica gel, chloroform/
diethyl ether, 8:2); IR (KBr): n ¼ 2944 s, 2868 m, 2361 w, 1702 s,
1608 m, 1519 m, 1450 m, 1376 w, 1288 w, 1196 w, 1115 w,
1
1013 m cmꢂ1; H-NMR (500 MHz, CDCl3): d ¼ 8.58 (s, 1H, CH
(triazole)), 8.29 (d, 2H, J ¼ 8.7 Hz, Ph), 7.92 (d, 2H, J ¼ 8.7 Hz,
Ph), 7.92 (d, 2H, J ¼ 8.7 Hz, Ph), 4.76 (d, 1H, J ¼ 2.1 Hz, CHa
(30)), 4.61 (dd, 1H, J ¼ 2.1, 1.5 Hz, CHb (30)), 3.17 (ddd, 1H,
J ¼ 13.8, 3.3, 3.3 Hz, CHa (16)), 2.97 (ddd, 1H, J ¼ 11.0, 11.0,
4.6 Hz, CH (19)), 2.70–2.56 (m, 2H, CH (13) þ CHa (22)), 2.53–
2.35 (m, 2H, CH2 (2)), 1.90 (ddd, 1H, J ¼ 12.3, 7.6, 4.5 Hz, CH (1)),
1.84–1.63 (m, 5H, CHa (12) þ CHb (16) þ CHa (21) þ CH
(18) þ CHb (22)), 1.71 (s, 3H, CH3 (29)), 1.47–1.28 (m,
10H, CH2 (11) þ CH2 (6) þ CHb (21) þ CH2 (7) þ CHb
(1) þ CH (9) þ CH (5)), 1.24–1.14 (m, 2H, CH2 (15)), 1.08–0.97
(m, 1H, CHb (12)), 1.04 (s, 3H, CH3 (23)), 1.00 (s, 3H, CH3 (27)), 0.99
–
–
–
–
–
CDCl ): d ¼ 218.3 (C O), 198.1 (C O), 170.4 (C O), 169.9 (C O),
–
–
–
3
–
–
–
–
–
169.2 (C O), 168.7 (C O), 150.7 (C20, C CH ), 147.8 (triazole,
–
2
–
Cquart.), 126.2 (triazole, CH), 109.5 (C30, CH2 C), 85.7 (Glc (1),
–
(s, 3H, CH3 (24)), 0.92 (s, 3H, CH3 (25)), 0.91 (s, 3H, CH3 (26)) ppm;
13
–
–
–
C-NMR (125 MHz, CDCl ): d ¼ 218.5 (C O), 198.6 (C O), 169.8
CH), 75.2 (Glc (5), CH), 72.4 (Glc (3), CH), 70.5 (Glc (2), CH), 67.5
(Glc (4), CH), 61.4 (Glc (6), CH2), 60.6 (C17, Cquart.), 54.9 (C5, CH),
50.1 (C18, CH), 50.0 (C9, CH), 47.2 (C4, Cquart.), 45.7 (C19, CH),
42.4 (C14, Cquart.), 40.6 (C8, Cquart.), 39.6 (C1, CH2), 36.9 (C10,
–
3
–
–
–
–
(C O), 150.7 (C20, C CH ), 148.4 (triazole, Cquart.), 140.0 (Ph,
2
C
quart.), 132.1 (Ph, CH), 129.9 (Ph, Cquart.), 125.5 (triazole, CH),
–
120.2 (Ph, CH), 109.5 (C30, CH2 C), 60.4 (C17, Cquart.), 54.9 (C5,
–
CH), 50.2 (C18, CH), 50.0 (C9, CH), 47.3 (C4, Cquart.), 45.9 (C19, CH),
42.5 (C14, Cquart.), 40.7 (C8, Cquart.), 39.6 (C1, CH2), 37.0 (C13, CH),
36.9 (C10, Cquart.), 36.1 (C22, CH2), 34.1 (C2, CH2), 33.6 (C7, CH2),
Cquart.), 36.8 (C13, CH), 36.1 (C22, CH2), 34.0 (C2, CH2), 33.5 (C7,
CH2), 31.5 (C16, CH2), 30.5 (C21, CH2), 29.6 (C15, CH2), 26.6 (C23,
CH3), 25.6 (C12, CH2), 21.5 (C11, CH2), 20.9 (C24, CH3), 20.6 (Ac),
ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

46
R. Csuk et al.
Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
20
20.4 (2 Ac), 20.2 (Ac), 19.6 (C6, CH2), 19.3 (C29, CH3), 15.9 (C26,
CH3), 15.8 (C25, CH3), 14.3 (C27, CH3) ppm; MS (ESI, MeOH):
m/z ¼ 836.0 (20%, [M þ H]þ), 858.3 (100%, [M þ Na]þ), 1693.2
(50%, [2 M þ Na]þ); anal. calcd. for C46H65N3O11 (836.02): C,
66.09; H, 7.84; N, 5.03; found: C, 65.74; H, 7.73; N, 4.83.
228–2308C; [a]D ¼ 2.48 (c ¼ 4.2, MeOH); Rf ¼ 0.55 (silica gel,
CH2Cl2/MeOH, 9:1); IR (KBr): n ¼ 2941 s, 2868 m, 1697 m,
1674 m, 1596 m, 1517 w, 1460 m, 1375 m, 1098 m,
1024 m cmꢂ1
;
1H-NMR (500 MHz, DMSO-d6): d ¼ 8.87 (s,
1H, CH (triazole)), 5.56 (d, 1H, J ¼ 9.2 Hz, Glc CH (1)), 4.68
(d, 1H, J ¼ 2.1 Hz, CHa (30)), 4.54 (dd, 1H, J ¼ 2.1, 1.5 Hz, CHb
(30)), 3.81 (dd, 1H, J ¼ 9.2, 9.1 Hz, Glc CH (2)), 3.65 (dd, 1H,
J ¼ 10.3, 4.6 Hz, Glc CHa (6)), 3.42–3.33 (m, 3H, Glc CHb
(6) þ CH (5) þ CH (3)), 3.24 (dd, 1H, J ¼ 8.8, 8.8 Hz, Glc CH
(4)), 2.93 (ddd, 1H, J ¼ 13.8, 3.3, 3.3 Hz, CHa (16)), 2.85 (ddd,
1H, J ¼ 11.0, 11.0, 4.6 Hz, CH (19)), 2.58 (ddd, 1H, J ¼ 12.7,
12.7, 5.0 Hz, CH (13)), 2.46–2.28 (m, 3H, CHa (22) þ CH2 (2)),
1.77 (ddd, 1H, J ¼ 12.3, 7.6, 4.5 Hz, CH (1)), 1.64–1.47 (m,
5H, CHa (12) þ CHb (16) þ CH (18) þ CHb (22) þ CHa (21)),
1.64 (s, 3H, CH3 (29)), 1.38–1.14 (m, 10H, CH2 (11) þ CH2
(6) þ CH (9) þ CHb (1) þ CHb (21) þ CH2 (7) þ CH (5)), 1.10–
0.98 (m, 2H, CH2 (15)), 0.94–0.82 (m, 1H, CHb (12)), 0.94 (s,
3H, CH3 (23)), 0.93 (s, 3H, CH3 (27)), 0.88 (s, 3H, CH3 (24)), 0.82
(s, 6H, CH3 (25) þ CH3 (26)) ppm; 13C-NMR (125 MHz, DMSO-
28-[1-(2,3,4,6-Tetra-O-acetyl-b-D-mannopyranosyl)-1H-
1,2,3-triazol-4-yl]-lup-20(29)-en-3,28-dione (13)
Compound 13 (0.25 g, 69%) was obtained from compound 7
(0.20 g, 0.43 mmol) and 2,3,4,6-tetra-O-acetyl-b-D-mannopyra-
nosyl azide (0.16 g, 0.43 mmol) following GP3 as a colorless
20
solid; mp 243–2458C; [a]D ¼ –26.68 (c ¼ 4.3, CHCl3);
Rf ¼ 0.17 (silica gel, CHCl3/Et2O, 9:1); IR (KBr): n ¼ 2950 s,
2871 m, 1760 s, 1706 m, 1675 m, 1514 w, 1460 m, 1370 m,
1222 s, 1166 w, 1061 m cmꢂ1 1H-NMR (500 MHz, CDCl3):
;
d ¼ 8.22 (s, 1H, CH (triazole)), 6.16 (s, 1H, Man CH (1)), 5.67
(d, 1H, J ¼ 2.1 Hz, Man CH (2)), 5.32 (dd, 1H, J ¼ 10.0, 10.0 Hz,
Man CH (4)), 5.25 (dd, 1H, J ¼ 10.0, 3.0 Hz, Man CH (3)), 4.69 (d,
1H, J ¼ 2.1 Hz, CHa (30)), 4.54 (dd, 1H, J ¼ 2.1, 1.5 Hz, CHb (30)),
4.27 (dd, 1H, J ¼ 12.6, 5.5 Hz, Man CHa (6)), 4.19 (dd, 1H,
J ¼ 12.6, 1.7 Hz, Man CHb (6)), 4.00 (ddd, 1H, J ¼ 10.0, 5.5,
1.7 Hz, Man CH (5)), 3.01 (ddd, 1H, J ¼ 13.8, 3.3, 3.3 Hz, CHa
(16)), 2.90 (ddd, 1H, J ¼ 11.0, 11.0, 4.6 Hz, CH (19)), 2.56 (ddd,
1H, J ¼ 12.7, 12.7, 5.0 Hz, CH (13)), 2.51–2.30 (m, 3H, CHa
(22) þ CH2 (2)), 2.06 (s, 3H, Ac), 2.03 (s, 6H, 2Ac), 1.94 (s, 3H,
Ac), 1.84 (ddd, 1H, J ¼ 12.3, 7.6, 4.5 Hz, CH (1)), 1.72–1.52 (m,
5H, CHa (12) þ CHb (16) þ CHa (21) þ CH (18) þ CHb (22)), 1.64
(s, 3H, CH3 (29)), 1.40–1.24 (m, 10H, CH2 (11) þ CH2 (6) þ CHb
(21) þ CHb (1) þ CH2 (7) þ CH (9) þ CH (5)), 1.17–1.04 (m,
2H, CH2 (15)), 0.98–0.87 (m, 1H, CHb (12)), 0.98 (s, 3H, CH3
(23)), 0.93 (s, 6H, CH3 (24) þ CH3 (27)), 0.87 (s, 3H, CH3 (25)),
0.86 (s, 3H, CH3 (26)) ppm; 13C-NMR (125 MHz, CDCl3):
–
–
–
–
d ): d ¼ 216.6 (C O), 197.9 (C O), 150.5 (C20, C CH ), 146.0
–
–
6
2
–
(triazole, Cquart.), 126.5 (triazole, CH), 109.7 (C30, CH2 C), 87.8
–
(Glc (1), CH), 80.2 (Glc (5), CH), 76.8 (Glc (3), CH), 71.9 (Glc (2),
CH), 69.4 (Glc (4), CH), 60.7 (Glc (6), CH2), 60.0 (C17, Cquart.), 53.9
(C5, CH), 49.6 (C18, CH), 49.2 (C9, CH), 46.5 (C4, Cquart.), 45.6
(C19, CH), 42.1 (C14, Cquart.), 40.2 (C8, Cquart.), 38.9 (C1, CH2),
36.4 (C13, CH), 36.4 (C10, Cquart.), 35.6 (C22, CH2), 33.6 (C2,
CH2), 33.0 (C7, CH2), 31.3 (C16, CH2), 30.1 (C21, CH2), 29.2 (C15,
CH2), 26.4 (C23, CH3), 25.3 (C12, CH2), 21.2 (C11, CH2), 20.7
(C24, CH3), 19.2 (C6, CH2), 18.9 (C29, CH3), 15.7 (C26, CH3), 15.5
(C25, CH3), 14.2 (C27, CH3) ppm; MS (ESI, MeOH): m/z ¼ 668.2
(10%, [M þ H]þ), 690.4 (100% [M þ Na]þ); anal. calcd.
for C38H57N3O7 (667.88): C, 68.34; H, 8.60; N, 6.29; found:
C, 67.99; H, 8.33; N, 5.83.
–
–
–
–
–
d ¼ 218.1 (C O), 198.5 (C O), 170.4 (C O), 169.7 (C O), 169.4
–
–
–
–
–
–
–
–
–
(C O), 169.0 (C O), 150.7 (C20, C CH ), 147.5 (triazole, Cquart.),
2
–
126.8 (triazole, CH), 109.5 (C30, CH2 C), 84.6 (Man (1), CH), 75.7
28-[1-(b-D-Mannopyranosyl)-1H-1,2,3-triazol-4-yl]-lup-
20(29)-en-3,28-dione (15)
Compound 15 (0.12 g, 90%) was obtained from compound 13
–
(Man (5), CH), 70.6 (Man (3), CH), 68.6 (Man (2), CH), 64.7 (Man (4),
CH), 62.0 (Man (6), CH2), 60.7 (C17, Cquart.), 54.9 (C5, CH), 50.1
(C18, CH), 50.0 (C9, CH), 47.2 (C4, Cquart.), 45.8 (C19, CH), 42.5
(C14, Cquart.), 40.6 (C8, Cquart.), 39.6 (C1, CH2), 37.0 (C13, CH), 36.9
(C10, Cquart.), 36.0 (C22, CH2), 34.1 (C2, CH2), 33.5 (C7, CH2), 31.7
(C16, CH2), 30.6 (C21, CH2), 29.6 (C15, CH2), 26.6 (C23, CH3), 25.6
(C12, CH2), 21.5 (C11, CH2), 20.9 (C24, CH3), 20.7 (Ac), 20.6 (Ac),
20.5 (Ac), 20.4 (Ac), 19.6 (C6, CH2), 19.3 (C29, CH3), 15.9 (C26,
CH3), 15.8 (C25, CH3), 14.4 (C27, CH3) ppm; MS (ESI, MeOH):
m/z ¼ 836.0 (20%, [M þ H]þ), 858.3 (100%, [M þ Na]þ), 1693.2
(30%, [2 M þ Na]þ); anal. calcd. for C46H65N3O11 (836.02): C,
66.09; H, 7.84; N, 5.03; found: C, 62.95; H, 7.46; N, 4.89.
(0.15 g, 0.18 mmol) following GP4 as a colorless solid; mp 267–
20
2708C; [a]D ¼ 12.38 (c ¼ 4.2, MeOH); Rf ¼ 0.55 (silica gel,
CH2Cl2/MeOH, 9:1); IR (KBr): n ¼ 2941 s, 2869 m, 1674 m,
1512 m, 1455 m, 1376 w, 1204 m, 1094 m, 1026 m cmꢂ1
;
1H-NMR (500 MHz, DMSO-d6): d ¼ 8.58 (s, 1H, CH (triazole)),
6.04 (s, 1H, Man CH (1)), 4.68 (d, 1H, J ¼ 2.1 Hz, CHa (30)), 4.54
(dd, 1H, J ¼ 2.1, 1.5 Hz, CHb (30)), 3.88 (d, 1H, J ¼ 2.1 Hz,
Man CH (2)), 3.70 (dd, 1H, J ¼ 12.6, 5.5 Hz, Man CHa (6)),
3.57 (dd, 1H, J ¼ 10.0, 3.0 Hz, Man CH (3)), 3.52–3.42 (m, 2H,
Man CH (4) þ CHb (6)), 3.26–3.14 (m, 1H, Man CH (5)), 2.93 (ddd,
1H, J ¼ 13.8, 3.3, 3.3 Hz, CHa (16)), 2.87 (ddd, 1H, J ¼ 11.0, 11.0,
4.6 Hz, CH (19)), 2.57 (ddd, 1H, J ¼ 12.7, 12.7, 5.0 Hz, CH (13)),
2.46–2.26 (m, 3H, CHa (22) þ CH2 (2)), 1.76 (ddd, 1H, J ¼ 12.3,
7.6, 4.5 Hz, CH (1)), 1.72–1.48 (m, 5H, CHa (12) þ CHb
(16) þ CHa (21) þ CH (18) þ CHb (22)), 1.64 (s, 3H, CH3 (29)),
28-[1-(b-D-Glucopyranosyl)-1H-1,2,3-triazol-4-yl]-lup-
20(29)-en-3,28-dione (14)
Compound 14 (0.11 g, 85%) was obtained from compound 12
(0.15 g, 0.18 mmol) following GP4 as a colorless solid; mp
ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
New Betulin Derivatives
47
1.40–1.24 (m, 10H, CH2 (11) þ CH2 (6) þ CHb (21) þ CHb
(1) þ CH2 (7) þ CH (9) þ CH (5)), 1.08–0.99 (m, 2H, CH2 (15)),
0.93–0.85 (m, 1H, CHb (12)), 0.93 (s, 6H, CH3 (23) þ CH3 (27)),
0.88 (s, 3H, CH3 (24)), 0.81 (s, 6H, CH3 (25) þ CH3 (26)) ppm; 13C-
(C4, Cquart), 38.8 (C1, CH2), 37.3 (C13, CH), 37.2 (C10, Cquart.),
34.3 (C7, CH2), 33.9 (C21, CH2), 33.2 (C16, CH2), 32.8 (C22, CH2),
28.1 (C23, CH3), 27.9 (C15, CH2), 27.5 (C2, CH2), 25.3 (C12, CH2),
21.0 (C11, CH2), 20.7 (Ac), 20.6 (Ac), 20.5 (Ac), 20.1(Ac), 18.4 (6,
CH2), 16.3 (C24, CH3), 16.1 (C26, CH3), 15.4 (C25, CH3), 15.4
(C27, CH3) ppm; MS (ESI, MeOH): m/z ¼ 840.4 (20%, [M þ H]þ),
826.5 (100%, [M þ Na]þ), 1702.3 (30%, [2 M þ Na]þ); anal.
calcd. for C46H67N3O11 (838.06): C, 65.93; H, 8.06; N, 5.01;
found: C, 65.72; H, 8.31; N, 4.88.
–
–
–
NMR (125 MHz, DMSO-d ): d ¼ 216.6 (C O), 198.0 (C O), 150.5
–
6
–
(C20, C CH ), 145.7 (triazole, Cquart.), 127.8 (triazole, CH), 109.7
–
–
(C30, CH2 C), 86.1 (Man (1), CH), 80.2 (Man (5), CH), 72.9 (Man
2
–
(3), CH), 70.2 (Man (2), CH), 65.9 (Man (4), CH), 60.9 (Man (6),
CH2), 60.0 (C17, Cquart.), 53.9 (C5, CH), 49.6 (C18, CH), 49.2 (C9,
CH), 46.5 (C4, Cquart.), 45.6 (C19, CH), 42.1 (C14, Cquart.), 40.2 (C8,
C
quart.), 39.8 (C1, CH2), 36.4 (C13, CH), 36.4 (C10, Cquart.), 35.5
28-[1-(b-D-Glucopyranosyl)-1H-1,2,3-triazol-4-yl]-betulin
(17)
Compound 17 (149 mg, 93%) was obtained from compound
(C22, CH2), 33.6 (C2, CH2), 33.0 (C7, CH2), 31.3 (C16, CH2), 30.1
(C21, CH2), 29.1 (C15, CH2), 26.4 (C23, CH3), 25.2 (C12, CH2), 21.1
(C11, CH2), 20.7 (C24, CH3), 19.2 (C6, CH2), 18.8 (C29, CH3), 15.7
(C26, CH3), 15.5 (C25, CH3), 14.2 (C27, CH3) ppm; MS (ESI,
MeOH): m/z ¼ 668.3 (20%, [M þ H]þ), 690.4 (100%,
[M þ Na]þ), 1357.3 (30%, [2 M þ Na]þ); anal. calcd.
for C38H57N3O7 (667.88): C, 68.34; H, 8.60; N, 6.29; found: C,
67.89; H, 8.66; N, 5.89.
16 (200 mg, 0.24 mmol) following GP4 as a colorless solid;
20
mp 206–2098C; [a]D ¼ –3.218 (c ¼ 5.7, MeOH); IR (KBr):
n ¼ 3417 br, 2941 s, 2870 s, 1725 w, 2639 m, 1455 s,
1376 m, 1251 m, 1042 s cmꢂ1 1H-NMR (500 MHz, CDCl3):
;
d ¼ 8.09
(s,
1H,
CH
triazole),
5.47
(d,
1H,
J ¼ 9.3 Hz, CHOH Glc (1)), 5.30–5.25 (m, 2H, CHOH Glc
(2) þ CHOH (28)), 5.19 (d, 1H, J ¼ 4.9 Hz, CHOH Glc (3)),
5.09 (d, 1H, J ¼ 5.5 Hz, CHOH Glc (4)), 5.03 (d, 1H,
J ¼ 5.0 Hz, CHOH (28)), 4.6 (d, 1H, J ¼ 2.2 Hz, CHa (30)),
4.59 (t, 1H, J ¼ 5.5 Hz, CHOH Glc (6)), 4.54–4.51 (m,
1H, CHb (30)), 4.24 (d, 1H, J ¼ 5.1 Hz, CHOH (3)), 3.79 (ddd,
1H, J ¼ 6.2, 9.1, 9.1 Hz, CHOH Glc (2)), 3.69 (dd, 1H, J ¼ 5.4,
10.0 Hz, CHa Glc (6)), 3.48–3.32 (m, 3H, CHb Glc
(6) þ CHOH Glc (5) þ CHOH Glc (3)), 3.26–3.19 (m,
1H, CHOH Glc (4)), 3.07 (ddd, 1H, J ¼ 6.2, 11.0, 11.0 Hz, CH
(19)), 2.97 (ddd, 1H, J ¼ 5.6, 5.6, 9.9 Hz, CHOH (3)), 2.20–2.05
(m, 2H, CH (13) þ CHa (21)), 1.95–1.90 (m, 2H, CHa (22)), 1.77–
1.66 (m, 2H, CH (18) þ CHa (2)), 1.65 (s, 3H, CH3 (29)), 1.60–1.54
(m, 1H, CHa (1)), 1.50–1.14 (m, 14H, CH (9) þ CH2 (6) þ CHb
(21) þ CH2 (7) þ CH2 (15) þ CH2 (11) þ CHa (16) þ CHb
(2) þ CH2 (12)), 1.11 (s, 3H, CH3 (27)), 1.09–1.00 (m, 1H, CHb
(16)), 0.97 (s, 3H, CH3 (25)), 0.95–0.89 (m, 1H, CHb (22)), 0.87 (s,
3H, CH3 (24)), 085–0.83 (m, 1H, CHb (1)), 0.80 (s, 3H, CH3 (26)),
0.66 (s, 3H, CH3 (23)), 0.65–0.60 (m, 1H, CH (5)) ppm; 13C-NMR
28-[1-(2,3,4,6-Tetra-O-acetyl-b-D-glucopyranosyl)-1H-
1,2,3-triazol-4-yl]-betulin (16)
Compound 16 (1.5 g, 85%) was obtained from compound 5
(1.0 g, 2.1mmol) and 2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl
azide (1.5 g, 4 mmol) following GP3 as a colorless solid; mp
20
222–2268C; [a]D ¼ 48 (c ¼ 5.4, CHCl3); Rf ¼ 0.16 (silica gel,
CHCl3/Et2O, 95/5) IR (KBr): n ¼ 3589 m, 3403 s, 3295 s,
2950 s, 1454 m, 1390 m, 1374 m, 1256 w, 1183 w, 1139 w,
1
1032 m cmꢂ1; H-NMR (500 MHz, CDCl3): d¼ 7.76 (s, 1H, CH
(triazol)), 5.85 (d, 1H, J ¼ 9.0 Hz, CH Glc (1)), 5.50–5.35 (m,
3H, CH Glc (2) þ CH Glc (3) þ CHOH (28)), 5.25–5.19 (m, 1H, CH
Glc (4)), 4.54 (d, 1H, J ¼ 1.3 Hz, CHa (30)), 4.48–4.50 (m, 1H, CHb
(30)), 4.29 (dd, 1H, J ¼ 5.2, 12.5 Hz, CHa Glc (6)), 4.18–4.14
(m, 1H, CHb Glc (6)), 3.98 (ddd, 1H, J ¼ 1.9, 4.7, 10.0 Hz, CH Glc
(5)), 3.19 (dd, 1H, J ¼ 4.9, 11.3 Hz, CHOH (3)), 3.00 (ddd, 1H,
J ¼ 5.8, 11.0, 11.0 Hz, CH (19)), 2.20–2.07 (m, 2H, CHa
(21) þ CH (13)), 2.06 (s, 3H, CH3), 2.04 (s, 3H, CH3), 1.99
(s, 3H, CH3), 1.95–183 (m, 2H, CHa (16) þ CHb (21)), 1.81
(s, 3H, CH3), 1.79–1.70 (m, 2H, CH2 (12)), 1.68 (s, 3H, CH3
(29)), 1.67–1.29 (m, 14H, CHb (16) þ CHa (1) þ CH2
(2) þ CH2 (11) þ CH2 (22) þ CH2 (7) þ CH2 (6) þ CH
(18) þ CH (9)), 1.18–1.14 (m, 2H, CH2 (15)), 1.12 (s, 3H, CH3
(27)), 1.09–1.01 (m, 1H, CHb (16)), 0.99 (s, 3H, CH3 (25)), 0.95
(s, 3H, CH3 (24)), 0.91–0.85 (m, 1H, CHb (1)), 0.82 (s, 3H, CH3
–
(125 MHz, CDCl ): d ¼ 151.8 (C20, C CH ),151.3 (triazole,
–
3
2
–
quart), 122.3 (triazole, CH), 109.7 (C30, CH2 C), 87.8 (Glc
–
C
(1), CH), 80.3 (Glc (5), CH), 77.6 (Glc (3), CH), 77.3 (C3,
CHOH), 72.4 (Glc (2), CH), 70.0 (Glc (4), CH), 67.6 (C28,
CHOH), 61.2 (Glc (6), CH), 55.4 (C5, CH), 50.3 (C9, CH), 50.1
(C18, CH), 50.0 (C17, Cquart.), 48.6 (C19, CH), 43.0 (C14, Cquart),
41.0 (C8, Cquart), 39.5 (C4, Cquart), 38.7 (C1, CH2), 37.2
(C10, Cquart.), 36.7 (C13, CH), 34.3 (C7, CH2), 34.0 (C16, CH2),
33.6 (C22, CH2), 32.8 (C21, CH2), 28.6 (C23, CH3), 27.9 (C15,
CH2), 27.6 (C2, CH2), 25.4 (C12, CH2), 20.9 (C11, CH2), 18.4 (C6,
CH2), 16.4 (C24, CH3), 16.3 (C26, CH3), 16.2 (C25, CH3), 15.5
(C27, CH3) ppm; MS (ESI, MeOH): m/z ¼ 672.5 (17%, [M þ H]þ),
694.5 (40%, [M þ Na]þ), 1365.5 (100%, 2 M þ Na]þ); anal.
calcd. for C38H59N3O7 (669.89): C, 68.13; H, 8.88; N, 6.27;
found: C, 67.86; H, 9.05; N, 6.05.
(26)), 0.74 (s, 3H, CH3 (23)), 0.67 (d, 1H, J ¼ 9.0 Hz, CH (5)) ppm;
13
–
–
–
C-NMR (125 MHz, CDCl ): d ¼ 171.0 (C O), 170.4 (C O),
–
3
–
–
–
–
–
–
169.8 (C O), 168.7 (C O), 151.4 (C20, C CH ),151.3 (triazole,
2
–
quart), 119.7 (triazole, CH), 109.5 (C30, CH2 C), 85.8 (Glc (1),
–
C
CH), 79.0 (C3, CH), 75.2 (Glc (5), CH), 72.7 (Glc (3), CH), 70.4 (Glc
(2), CH), 69.1 (C28, CHOH), 67.9 (Glc (4), CH), 61.6 (Glc (6), CH2),
55.4 (C5, CH), 50.4 (C9, CH), 50.3 (C17, Cquart), 50.2 (C18, CH),
48.8 (C19, CH), 43.2 (C14, Cquart), 41.1 (C8, Cquart), 38.9
ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

48
R. Csuk et al.
Arch. Pharm. Chem. Life Sci. 2011, 1, 37–49
[2] T. G. Tolstikova, I. V. Sorokina, G. A. Tolstikov, A. G.
Tolstikov, O. B. Flekhter, Russ. J. Bioorg. Chem. 2006, 32,
37–49.
28-(2-(Dimethylamino)ethenyl)lup-20(29)-en-3,28-dione-
(18)
A solution of compound 7 (0.20 g, 0.40 mmol) and DIMCARB
(0.13 g, 1.00 mmol) in EtOH (10 mL) was stirred for 24 h at
room temperature. The solution was concentrated in vacuo
and the residue was subjected to column chromatography
(silica gel, hexane/ethyl acetate, 8:2). Compound 18 (0.2 g,
97%) was obtained as a colorless solid; mp 249–2508C;
[3] J. F. Mayaux, A. Bousseau, R. Pauwels, T. Huet, Y. Henin, N.
Dereu, M. Evers, F. Soler, C. Poujade, Proc. Natl. Acad. Sci. U. S.
A. 1994, 91, 3564–3568.
[4] B. Labrosse, C. Treboute, M. Alizon, J. Virol. 2000, 74, 2142–
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[5] J. Zhou, Y. Xiong, D. Dismuke, B. M. Forshey, C. Lundquist,
K.-H. Lee, C. Aiken, C. H. Chen, J. Virol. 2004, 78, 922–
929.
20
[a]D ¼ 7.08 (c ¼ 3.6, CHCl3); Rf ¼ 0.27 (silica gel, hexane/
ethyl acetate, 8:2); IR (KBr): n ¼ 3067 w, 2945 s, 2864 m,
[6] F. Li, R. Goila-gaur, K. Salzwedel, N. R. Kilgore, M. Reddick, C.
Matallana, A. Castillo, D. Zoumplis, D. E. Martin, J. M.
Orenstein, G. P. Allaway, E. O. Freed, C. T. Wild, Proc. Natl.
Acad. Sci. U. S. A. 2003, 100, 13555–13560.
1700 s, 1659 s, 1574 s, 1457 m, 1432 m, 1354 m, 1300 w,
1221 w, 1138 w, 1101 w, 1055 s cmꢂ1 1H-NMR (500 MHz,
;
CDCl3): d ¼ 7.52 (d, 1H, J ¼ 12.5 Hz, CH (32)), 5.22 (d, 1H,
J ¼ 12.5 Hz, CH (31)), 4.71 (d, 1H, J ¼ 2.1 Hz, CHa (30)), 4.54
(dd, 1H, J ¼ 2.1, 1.5 Hz, CHb (30)), 3.07 (ddd, 1H, J ¼ 11.2, 11.0,
4.9 Hz, CH (19)), 2.89 (br s, 6H, NMe), 2.68 (ddd, 1H, J ¼ 12.8,
11.6, 3.8 Hz, CH (13)), 2.52–2.32 (m, 2H, CH2 (2)), 2.28–2.22
(ddd, 1H, J ¼ 12.8, 3.1, 3.1 Hz, CHa (16)), 1.92–1.68 (m, 4H, CHa
(1) þ CHa (22) þ CHa (21) þ CHa (12)), 1.66 (s, 3H, CH3 (29)),
1.51–1.22 (m, 14H, CH (18) þ CHb (16) þ CH2 (6) þ CH2
(11) þ CHa (15) þ CH2 (7) þ CHb (1) þ CH (9) þ CHb
(22) þ CHb (21) þ CH (5)), 1.09 (ddd, 1H, J ¼ 13.0, 3.6,
3.0 Hz, CHb (15)), 0.95–0.87 (m, 1H, CHb (12)), 1.04 (s,
3H, CH3 (23)), 1.00 (s, 3H, CH3 (24)), 0.95 (s, 6H, CH3
(25) þ CH3 (27)), 0.90 (s, 3H, CH3 (26)) ppm; 13C-NMR
[7] E. Pisha, H. Chai, I. S. Lee, T. E. Chagwedera, N. R.
Farnsworth, G. A. Cordell, C. W. W. Beecher, H. H. S.
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M. E. Peter, K. M. Debatin, J. Biol. Chem. 1998, 273, 33942–
33948.
[9] S. Fulda, K. M. Debatin, Med. Pediatr. Oncol. 2000, 35, 616–
618.
[10] W. Wick, C. Grimmel, B. Wagenknecht, J. Dichgans,
M. Weller, J. Pharmacol. Exp. Ther. 1999, 289, 1306–
1312.
[11] Y. Tan, R. Yu, J. M. Pezzuto, Clin. Cancer Res. 2003, 9, 2866–
2875.
–
–
–
(125 MHz, CDCl ): d ¼ 218.3 (C O), 201.9 (C O), 152.2
–
3
[12] A. Barthel, S. Stark, R. Csuk, Tetrahedron 2008, 64, 9225–
9229.
–
–
–
–
(C32, HC), 151.7 (C20, C CH ), 108.9 (C30, CH C), 92.4
2
2
(C31, HC), 58.9 (C17, Cquart.), 55.0 (C5, CH), 50.1 (C9, CH),
49.7 (C18, CH), 47.3 (C4, Cquart.), 46.4 (C19, CH), 42.6 (C14,
[13] A. Pichette, H. Y. Liu, C. Roy, S. Tanguay, F. Simard, S. Lavoie,
Synthetic Commun. 2004, 34, 3925–3927.
C
quart.), 40.7 (C8, Cquart.), 39.6 (C1, CH2), 37.8 (C22, CH2), 37.0
[14] S. Coustal, J. Fagart, E. Davioud, A. Marquet, Tetrahedron
1995, 51, 3559–3570.
(C13, CH), 36.9 (C10, Cquart.), 34.2 (C2, CH2), 33.7 (C7, CH2), 30.7
(C16, CH2), 29.6 (C21, CH2), 29.6 (C15, CH2), 26.6 (C23, CH3),
25.8 (C12, CH2), 21.6 (C11, CH2), 21.0 (C24, CH3), 19.7 (C6, CH2),
19.4 (C29, CH3), 16.1 (C26, CH3), 16.0 (C25, CH3), 14.4 (C27, CH3)
ppm; MS (ESI, MeOH): m/z ¼ 508.8 (100%, [M þ H]þ); anal.
calcd. for C34H53NO2 (507.79): C, 80.42; H, 10.52; N, 2.76;
found: C, 80.33; H, 10.65; N, 2.66.
[15] J. G. Cui, L. L. Huang, L. Fan, A. M. Zhou, Steroids 2008, 73,
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[18] N. Jiang, C.-J. Li, Chem. Commun. 2004, 394–395.
We like to thank Dr. Harish Kommera and PD Dr. Reinhard Paschke
from Biosolutions Halle GmbH for support. Many thanks are due to
Dr. Dieter Stro¨hl for NMR measurements and to Dr. Ralph Kluge for
numerous ESI-MS spectra. Furthermore, we thank the Stiftung der
Deutschen Wirtschaft (SDW) for a personal scholarship (to Stefan
Schwarz), and Dr. Thomas Mu¨ller from the Dept. of Haematology/
Oncology for providing the cell lines.
[19] K. von Auwers, O. Ungemach, Ber. Deutsch. Chem. Ges. 1933, 66,
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[20] G. T. Shchetnikov, A. S. Peregudov, S. N. Osipov, Synlett 2007,
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The authors have declared no conflict of interest.
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New Betulin Derivatives
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www.archpharm.com