New iridoids from Asperula maximowiczii

Article abstract of DOI:10.1021/np020017q

Three new dimeric iridoid glucosides, named asperuloides A (1), B (2), and C (3), were isolated from Asperula maximowiczii, along with the known compound picconioside II. The structures of the new compounds were determined by spectroscopic and chemical methods and by the single-crystal X-ray diffraction analysis of 1.

Full text of DOI:10.1021/np020017q

J . Nat. Prod. 2002, 65, 1363-1366
1363
New Ir id oid s fr om Asper u la m a xim owiczii
Aeri Park, Hyoung J a Kim, J i Sun Lee, Eun-Rhan Woo, Hokoon Park, and Yong Sup Lee*
Division of Life Sciences, Korea Institute of Science & Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Korea
Received J anuary 25, 2002
Three new dimeric iridoid glucosides, named asperuloides A (1), B (2), and C (3), were isolated from
Asperula maximowiczii, along with the known compound picconioside II. The structures of the new
compounds were determined by spectroscopic and chemical methods and by the single-crystal X-ray
diffraction analysis of 1.
Asperula maximowiczii Komarov belongs to the family
Rubiaceae, which is a perennial plant distributed on damp
ground in Korea, China, and Taiwan. Flavonoids, an-
thraquinones, and iridoids have been isolated from the
other species of the same genus (i.e., A. odorata, A.
oppositifolia, and A. tinctoria).1 However, phytochemical
studies have not been carried out on this plant. During our
search for biologically active compounds from plant sources,
A. maximowiczii was selected for investigation. Separation
and isolation of the alcoholic extract of A. maximowiczii
collected from Kang-Won, Korea, afforded three new dimer-
ic iridoid glucosides, named asperuloides A (1), B (2), and
C (3), along with the known iridoid picconioside II.2 In this
paper, we report the isolation and structural determination
of 1-3.
asperuloides A, B, and C (1-3), and the EtOAc-soluble
extract gave asperuloide C (3) and piccouioside II.
Compound 1 was obtained as colorless needles upon
recrystallization from CH2Cl2-MeOH. Its molecular for-
mula, C27H38O13, was established by HRFABMS. The IR
spectrum indicated the presence of hydroxyl (3422 cm-1),
ester (1718 cm-1), and R,â-conjugated ester (1646 cm-1
)
groups. The 1H NMR spectrum showed a singlet for the
11-carbomethoxy group at 3.69 ppm, as confirmed by the
signal of the olefinic H-3 at 7.43 ppm (d, J ) 1.3 Hz), which
was highly deshielded by an ester carbonyl group. Two
hemiacetal proton signals at 5.24 (d, J ) 5.4 Hz) and 4.66
ppm (d, J ) 7.9 Hz) were assigned to H-1 and the anomeric
proton of a â-D-glucopyranosyl moiety, respectively. The 1H
NMR signals for the iridoid moiety of 1 (Table 1) and
loganin3 differed only in the chemical shifts for H-7 and
H-8. These signals were shifted downfield by 1.12 and 0.29
ppm in the spectrum of 1. These chemical shift differences
in H-7 and H-8 were expected, since the δ-lactone moiety
is linked to C-7 of loganin.4 In their 13C NMR spectra, most
of the signals for the loganin moiety of 1 (Table 2) and in
loganin3 had very similar chemical shifts to each other
except for the signals at C-6, C-7, and C-8.5 Significant
differences between the spectra of 1 and loganin were the
large downfield shift (+4.65 ppm) of the C-7 signal and
smaller upfield shifts for C-6 and C-8 (-2.3 and -1.4 ppm)
in 1 owing to an R-effect caused by acylation of the
7-hydroxy group.6 On the basis of the 1H-1H COSY and
HMQC spectral data, the remaining proton signals of the
δ-lactone moiety in 1 could be assigned.
The HMBC spectrum of compound 1 indicated that the
carbonyl carbon signal (δ 176.0, C-1′′) of the δ-lactone
moiety showed a 1H-13C long-range correlation with the
H-3′′ signal. The 13C NMR signal (δ 171.6, C-11′′) of the
other carbonyl group was correlated with the 1H NMR
signal at δ 3.23 (H-4′′). These data indicated that the
carbonyl groups of the ester were located at C-9′′ and C-4′′
of the lactone part, respectively. The proton signal pattern
of this δ-lactone unit was very close to that of scaevoloside,
previously isolated from Scaevola racemigera.7 The con-
formation of the loganin portion and the configuration of
iridolactone in 1 were determined by NOE observations.
Signals at H-5 and H-9 were determined as being in a cis
configuration by their NOE correlations. On irradiation at
H-9, the H-5 and H-10 signals were enhanced by 5%, but
enhancements of the H-8 and H-1 signals were not ob-
served. On the basis of the assumption that H-9 has the
usual â-configuration, the methyl group at C-8 and H-5
could also be assigned with a â-configuration. The irradia-
tion of the H-9′′ signal led to enhancement of both the H-5′′
and H-10′′ signals. As a result, H-9′′ was deduced to be cis
to H-5′′ and H-8′′ trans to H-9′′. To confirm the stereo-
From the methanolic extract of the air-dried whole plant
of A. maximowiczi, the CH2Cl2-soluble portion afforded
* To whom correspondence should be addressed. Tel: +82-2-958-5167.
Fax: +82-2-958-5189. E-mail: yslee@kist.re.kr.
10.1021/np020017q CCC: $22.00
© 2002 American Chemical Society and American Society of Pharmacognosy
Published on Web 08/22/2002

1364 J ournal of Natural Products, 2002, Vol. 65, No. 9
Notes
Ta ble 1. 1H NMR Data (CD3OD, 500 MHz) of Compounds 1-3
position
1
2
3
H-1
H-3
5.24 d (5.4)
7.43 d (1.3)
5.25 d (5.1)
7.41 d (1.3)
5.33 d (3.8)
7.40 d (1.2)
H-5
3.08 dd (7.9, 7.7)
1.71 ddd (14.0, 8.5, 4.8)
2.29 ddd (14.5, 7.5, 1.2)
5.16 t (4.7)
2.15 td (13.6, 6.9)
2.03 td (8.7, 5.5)
1.08 d (6.9)
3.10 dd (7.9, 7.5)
1.73 ddd (14.4, 8.1, 5.2)
2.27 ddd (14.4, 11.8, 7.5)
5.16 dd (4.8, 3.9)
2.14 m
3.10 m
H-6R
H-6â
H-7
H-8
H-9
1.76 ddd (14.7, 7.2, 5.3)
2.33 ddd (14.8, 8.1, 1.6)
5.12 br t (3.8)
2.10 m
2.10 m
1.11 d (6.5)
2.04 td (8.8, 5.1)
1.06 d (6.9)
H-10
H-1′
H-2′
H-3′
H-4′
H-5′
H-6R′
H-6â′
H-3R′′
H-3â′′
H-4′′
H-5′′
H-6′′
H-6′′
H-7R′′
H-7â′′
H-8′′
H-9′′
H-10′′
OMe
4.66 d (7.9)
4.65 d (7.9)
4.66 d (7.9)
3.20 dd (9.1, 7.9)
3.37 dd (9.0, 8.7)
3.26 dd (9.6, 8.6)
3.31 m
3.64 dd (11.9, 6.1)
3.90 dd (11.9, 2.1)
4.42 m
3.23 m
2.96 m
1.53 m
1.93 m
1.28 m (12.1, 6.4)
1.98 m
2.09 m
2.52 t (10.6)
1.18 d (6.4)
3.69 s
3.19 dd (9.1, 7.9)
3.36 dd (9.0, 8.7)
3.28 dd (9.6, 8.6)
3.30 m
3.65 dd (11.9, 6.1)
3.89 dd (11.9, 2.1)
4.38 dd (11.3, 7.6)
4.49 dd (11.3, 3.2)
2.65 td (7.4, 3.2)
2.84 m
1.44 m (9.7, 6.4)
2.10 m
1.23 m (12.0, 6.5)
2.03 m (6.1, 1.6)
2.20 m
3.18 dd (8.0, 7.9)
3.37 dd (8.9, 8.7)
3.27 dd (9.6, 8.5)
3.31 m
3.66 dd (11.9, 5.8)
3.90 dd (11.9, 2.1)
3.72 dd (13.9, 7.2)
3.83 dd (10.8, 3.7)
2.60 m (11.0, 2.9)
2.50 m
1.57 m (11.1, 8.2)
1.90 m (11.1, 6.7)
1.22 ddd (7.3, 6.3, 2.1)
2.04 m (7.9, 1.7)
2.25 ddd (14.4, 7.3, 4.1)
2.55 m
2.54 dd (11.1, 9.2)
1.18 d (6.6)
3.66 s
1.06 d (6.9)
3.69 s, 3.66 s
Ta ble 2. 13C NMR Data (CD3OD, 125 MHz) of Compounds
1-3a
carbon
1
2
3
C-1
C-3
C-4
C-5
97.7 d
152.7 d
112.8 s
32.9 d
40.4 t
97.5 d
152.5 d
113.0 s
32.7 d
40.4 t
97.1 d
152.2 d
113.5 s
32.9 d
40.4 t
C-6
C-7
C-8
C-9
79.4 d
40.8 d
46.9 d
13.8 q
169.2 s
100.2 d
74.7 d
78.0 d
71.6 d
78.4 d
62.8 t
176.0 s
66.0 t
43.2 d
38.5 d
28.9 t
79.7 d
40.8 d
46.9 d
13.7 q
169.2 s
100.2 d
74.7 d
77.9 d
71.6 d
78.3 d
62.8 t
176.3 s
68.2 t
46.7 d
40.2 d
33.3 t
79.1 d
40.8 d
47.2 d
13.5 q
169.2 s
100.1 d
74.7 d
78.0 d
71.6 d
78.3 d
62.7 t
177.4 s
63.7 t
51.7 d
42.1 d
32.1 t
C-10
C-11
C-1′
C-2′
C-3′
C-4′
C-5′
C-6′
C-1′′
C-3′′
C-4′′
C-5′′
C-6′′
C-7′′
C-8′′
C-9′′
C-10′′
C-11′′
OMe
F igu r e 1. ORTEP drawing of compound 1.
36.1 t
35.5 t
34.4 t
F igu r e 2. NOESY (T) and HMBC (- - ->) correlations for compound
2.
42.8 d
51.3 d
19.1 q
171.6 s
51.7 q
40.7 d
50.0 d
20.0 q
172.7 s
51.7 q
40.0 d
52.0 d
21.9 q
175.4 s
51.4 q
51.6 q
corresponding to H-3′′ and H-4′′ were not found, leading
to the formulation of structure 4. Loganin was identified
by comparison with an authentic sample.3
Compound 2 was obtained as an amorphous powder and
was assigned the same molecular formula, C27H38O13, as
that of 1. All the signals in the H NMR spectrum of 2 for
a
Assignments were confirmed by DEPT, 1H-1H COSY, HMQC,
and HMBC methods.
1
chemistry of compound 1, a single-crystal X-ray analysis8
was carried out. The absolute configuration was established
from data on the configuration of the anomeric proton of
the â-D-glucose unit of the loganin moiety, as shown in
Figure 1. The identification deduced spectroscopically was
therefore fully confirmed.
Alkaline hydrolysis of compound 1 with sodium hydrox-
ide provided two compounds, loganin3 and compound 4. The
1H NMR spectrum of compound 4 revealed a set of new
terminal ethylene signals at 6.14 and 5.54 ppm. The signals
the loganin unit and for an iridolactone moiety were in good
agreement with those of 1. However, the H-4′′ signal in 2
was shifted upfield by 0.58 ppm when compound with 1,
as confirmed from the HMBC spectrum (Figure 2). Fur-
1
thermore, the H NMR spectrum of 2 exhibited an AB part
of an ABX system at δ 4.38 (dd, J ) 11.2, 7.5 Hz) and 4.49
(dd, J ) 11.2, 3.2 Hz), indicating the presence of a
1
methylene group in the lactone ring. The H and 13C NMR
(Tables 1 and 2) spectra of 2 were very similar to those of
compound 1 except for the distinct differences in the

Notes
J ournal of Natural Products, 2002, Vol. 65, No. 9 1365
over silica gel by elution with CH2Cl2-MeOH (95:5) to give
three subfractions (DG1-DG3). Subfraction DG2 (802.7 mg)
was further purified by column chromatography over LiChro-
prep RP-18 (2.5 × 30 cm) using 30% CH3CN as eluting solvent
and finally purified by preparative HPLC eluted with hexane-
MeOH-i-PrOH (70:17:13) to afford 640.1 mg of compound 1
and 84.2 mg of compound 2.
Fraction DH (2.3 g) was purified by column chromatography
over silica gel using CH2Cl2-MeOH (90:10) to give six sub-
fractions (DH1-DH6). Subfraction DH3 (382.6 mg) was fur-
ther purified by column chromatography over LiChroprep RP-
18 (2.5 × 30 cm) using 30% CH3CN for elution and finally
purified by preparative HPLC as described above to give 5.0
mg of compound 3.
The EtOAc-soluble layer (2.93 g) was chromatographed on
silica gel using gradient mixtures of CH2Cl2-MeOH (95:5 f
50:50) to give seven fractions (EA-EG). Fraction EC (165.2
mg) was purified by column chromatography over silica gel
with CH2Cl2-MeOH (90:10) to give three fractions (EC1-
EC3). Fraction EC2 was further purified by HPLC using CH3-
CN-H2O (25:75) to give an additional amount of compound 3
(3 mg). Fraction EE (501.4 mg) was purified by column
chromatography over silica gel with EtOAc-MeOH (90:10 f
25:75) to give six fractions (EE1-EE6). Fraction EE2 was
purified by preparative TLC on silica gel (1 mm, 20 × 20 cm,
Merck), developed with CH2Cl2-MeOH (80:20), to afford 15.9
mg of compound 4.
resonances due to an iridolactone moiety. The chemical
shifts of all carbons were determined by correlation with
the proton chemical shifts assigned by detailed decoupling
experiments. Accordingly, the 13C NMR spectrum of 2 was
fully assigned, as shown in Table 2. These data also
supported the proposed structure 2. The stereochemistry
of compound 2 was determined by NOESY data, which
showed correlations between H-9′′ and H-5′′ but not
between H-4′′ and H-5′′, demonstrating a cis configuration
for the C-11′′ carbonyl group and H-5′′ (Figure 2). As a
result, the absolute structure of compound 2 was deter-
mined as shown.
Compound 3 was obtained as an amorphous powder,
whose composition was determined to be C28H43O14 by
HRFABMS. Compound 3 was considered to be closely
related structurally to compound 1, since their IR and UV
spectra were essentially the same. Compound 3 exhibited
1
two distinctive signals for methoxy groups from the H and
13C NMR spectra. An upfield shift of the H-3′′ signal was
observed, indicating the opening of the lactone ring of 1
(Table 1). The configuration of the methyl ester could be
proposed, since a connectivity in the HMBC spectrum was
observed between H-9′′ at δ 2.55 and C-1′′ at δ 177.4 of
the methyl ester. The correlations between H-3′′ (δ 3.72
and 3.83) and C-4′′ (δ 51.7), and H-3′′ and C-11′′ (δ 175.4),
were also observed. The structure of 3 was thus estab-
lished. Since compounds 1 and 2 did not decompose under
any of the laboratory conditions applied or in solution of
MeOH, compound 3 does not appear to be an extraction
artifact.
Asp er u loid e A (1): colorless needles from MeOH-CH2Cl2
(9:1); [R]22 -19.5° (c 1.52, CHCl3); UV λmax (MeOH) 235 (log
D
ꢀ 3.93) nm; IR (KBr) νmax 3422, 2957, 1718, 1646 cm-1; 1H and
13C NMR data, see Tables 1 and 2; HRFABMS m/z 571.2382
[M + H]+ (calcd for C27H39O13, 571.2391).
X-r a y Str u ctu r e Deter m in a tion of 1.8 Suitable colorless
crystals of 1 were obtained by recrystallization from MeOH-
CH2Cl2 (9:1). The X-ray data were collected on an Enraf-
Nonius CAD4 automated diffractometer equipped with a Mo
X-ray tube (λ ) 0.71073 Å) and a graphite crystal monochro-
mator. The crystal (0.2 × 0.1 × 0.05 mm) belongs to the
monoclinic system, space group C2, with a ) 26.144(7) Å, b )
Picconioside II was identified by comparing its physical
and spectral data with literature values.2
Exp er im en ta l Section
Gen er a l Exp er im en ta l P r oced u r es. Melting points were
determined on a Thomas-Hoover capillary melting apparatus
and are uncorrected. Optical rotations were determined on an
Autopol III automatic polarimeter (Rudolph Research Co.,
Flanders, NJ ). UV spectra were taken with a Shimazu UV 240
UV-visible recording spectrometer. IR spectra were recorded
on a Perkin-Elmer 16F-PC FT-IR instrument using potassium
bromide pellets. NMR spectra were recorded on a Bruker
AMX-500 (500 MHz) spectrometer. 1H-1H COSY, NOE,
NOESY, HMQC, and HMBC NMR spectra were obtained with
the usual pulse sequences, and data processing was performed
with the standard Bruker software. HRFABMS were deter-
mined on a J EOL J MS-HX 110/100A mass spectrometer.
Preparative HPLC was performed on a Waters pump (model
510) with a photodiode array detector (Waters model 996)
using a ChiraSper (10 mm × 250 mm, Merck) column. TLC
and column chromatography were carried out on precoated
silica gel F254 plates (Merck, art. 5715), RP-18 F254S plates
(Merck, art. 15423), silica gel 60 (Merck, 230-400 mesh), and
Lichroprep RP-18 (Merck, 40-63 µm).
P la n t Ma ter ia l. The whole plants of Asperula maximow-
iczii were collected at Mt. Odae, Korea, in August 1994, and
the species was identified by Dr. J ong Hwan Kwak at Korea
Institute of Science and Technology (KIST). Voucher specimens
(398-20) have been deposited in our laboratory at KIST.
Extr a ction a n d Isola tion . The whole plants (697.0 g) were
air-dried in the dark and then extracted with a methanol to
give methanol-soluble extract. The dried extract residue (97.0
g) was suspended in water and sequentially partitioned with
methylene chloride, ethyl acetate, and n-butanol. The meth-
ylene chloride extract was evaporated under reduced pressure
to yield 30.4 g of a residue. This residue was divided into 12
fractions (DA-DL) by column chromatography on silica gel
using the following solvent mixtures: CH2Cl2-EtOAc (75:25
f 25:75), CH2Cl2-MeOH (90:10 f 25:75), and a MeOH wash.
Fraction DG (3.7 g) was purified by column chromatography
8.704(5) Å, c ) 14.209(6) Å, V ) 3131(2) Å3, Z ) 4, Dcalcd
)
1.342 g/cm3. The orientation matrix and unit cell dimensions
were determined from 25 machine-centered reflections in the
2θ range from 15° to 25°. The variation of intensities was
monitored by a repeated check of intensities of three reflections
every 1 h during the data collection period. A direct method
(SHELXS-90)9 was employed to find all the atoms. Subsequent
cycles of Fourier map and least-squares refinement were
followed (SHELXL-97).9 Absolute configuration was deter-
mined by known conformation of the anomeric proton of â-D-
glucose of the loganin moiety. All non-hydrogen atoms were
refined anisotropically for 1. Hydrogen atoms were included
in the structure factor calculation using a riding model. All
the calculations were carried out using VAX and PC comput-
ers. The refinement converged to a final R1 ) 0.083, wR2
)
0.2238, where R1 ) ∑||Fo| - |Fc||/∑|Fo, wR2 ) {∑w(Fo - Fc2)2/
2
4
∑wFo
}
1/2, for 1860 observed reflections [I > 2σ(I)] and 397
variable parameters.
Asp er u loid e B (2): amorphous powder; [R]18 -40.6° (c
D
0.38, MeOH); UV λmax (MeOH) 236 (log ꢀ 4.02) nm; IR (KBr)
νmax 3414, 2956, 1726, 1634, 1440, 1288, 1076 cm-1; H and
1
13C NMR data, see Tables 1 and 2; HRFABMS m/z 571.2410
[M + H]+ (calcd for C27H39O13, 571.2391).
Asp er u loid e C (3): amorphous powder; [R]19 -53.2° (c
D
0.063, MeOH); UV λmax (MeOH) 235 (log ꢀ 3.88) nm; IR (KBr)
νmax 3422, 2956, 1718, 1634, 1440, 1288, 1076 cm-1; H and
1
13C NMR data, see Tables 1 and 2; HRFABMS m/z 603.2663
[M + H]+ (calcd for C28H43O14, 603.2653).
Alk a lin e Hyd r olysis of Asp er u loid e A (1). To a solution
of compound 1 (53.2 mg) in MeOH (3 mL) was added 1 N
NaOH (2 mL), and the mixture was stirred at room temper-
ature for 12 h. The reaction mixture was neutralized by
addition of Amberlite IR-120 (H+-form). After removing the
resin by filtration, the filtrate was evaporated. The residue
was dissolved in 2 mL of MeOH and treated with CH2N2. After
the reaction was completed, the solvent was evaporated in

1366 J ournal of Natural Products, 2002, Vol. 65, No. 9
Notes
vacuo. The resulting mixture was purified by preparative TLC
(precoated silica gel F254 plates (20 × 20 cm, 1 mm, Merck,
art. 13895, CH2Cl2-MeOH, 85:15) to afford loganin (5.5 mg),
identical to an authentic sample,3 and compound 4 (32.9 mg)
lographic analysis at KIST. This work was supported by grants
from the Ministry of Science and Technology, Korea (2N23260).
Su p p or tin g In for m a tion Ava ila ble: Details of crystal data for
compound 1. This material is available free of charge via the Internet
at http://pubs.acs.org.
as an amorphous powder: [R]24 -49.0° (c 0.083, MeOH); IR
D
(KBr) νmax 3422, 2956, 1708, 1632, 1440, 1288, 1160, 1076 cm-1
;
1H NMR (CD3OD, 300 MHz) δ 1.02 (3H, d, J ) 6.7 Hz, H-10′′),
1.04 (3H, d, J ) 5.5 Hz, H-10), 1.21 (1H, m, H-7′′), 1.69 (1H,
m, H-6), 1.76 (2H, m, H-6′′), 2.01 (1H, m, H-7′′), 2.05 (1H, m,
H-9), 2.09 (1H, m, H-8), 2.26 (1H, ddd, J ) 14.8, 8.0, 1.3 Hz,
H-6), 2.36 (1H, m, H-8′′), 2.65 (1H, dd, J ) 9.1, 5.9 Hz, H-9′′),
3.04 (1H, q, J ) 7.7 Hz, H-5), 3.14 (1H, dd, J ) 8.9, 7.9 Hz,
H-2′), 3.23 (1H, m, H-5′), 3.24 (1H, m, H-3′), 3.30 (1H, m, H-5′′),
3.33 (1H, m, H-4′), 3.58 (1H, dd, J ) 11.9, 5.7 Hz, H-6′), 3.62
(3H, s, OMe), 3.83 (1H, dd, J ) 11.8, 1.8 Hz, H-6′), 4.59 (1H,
d, J ) 7.8 Hz, H-1′), 5.11 (1H, dd, J ) 4.3, 4.0 Hz, H-7), 5.25
(1H, d, J ) 4.2 Hz, H-1), 5.54 (1H, s, H-3′′), 6.14 (1H, s, H-3′′),
7.36 (1H, d, J ) 1.0 Hz, H-3); 13C NMR (CD3OD, 75 MHz) δ
14.1 (C-10), 21.8 (C-10′′), 31.5 (C-6′′), 32.8 (C-5), 35.0 (C-7′′),
38.8 (C-8′′), 40.6 (C-6), 41.4 (C-8), 45.2 (C-5′′), 47.5 (C-9), 52.1
(OMe), 57.0 (C-9′′), 63.1 (C-6′), 71.9 (C-4′), 75.1 (C-2′), 78.3 (C-
3′), 78.7 (C-5′), 79.6 (C-7), 97.7 (C-1), 100.5 (C-1′), 113.6 (C-
4′′), 125.0 (C-3′′),143.2 (C-4), 152.9 (C-3), 168.5 (C-11′′), 169.8
(C-11), 178.6 (C-1′′); HRFABMS m/z 571.2394 [M + H]+ (calcd
for C27H39O13, 571.2391).
Refer en ces a n d Notes
(1) Corrigan, D.; Timoney, R. F.; Donnelly, D. M. X. Phytochemistry 1978,
17, 1131-1133.
(2) Damtoft, S.; Franzyk, H.; J ensen, S. R. Phytochemistry 1997, 45, 743-
750.
(3) Mu¨ller, A. A.; Weigend, M. Phytochemistry 1998, 49, 131-135.
(4) J esen, S. R.; Lyse-Petersen, S. E.; Nielsen, B. J . Phytochemistry 1979,
18, 273-277.
(5) Damtoft, S.; J ensen, S. R.; Nielsen, B. J . Phytochemistry 1981, 20,
2717-2732.
(6) (a) Chaudhuri, R. K.; Afifi-Yazar, F. U¨ .; Sticher, O. Tetrahedron 1980,
36, 2317-2326. (b) Bonini, C.; Davini, E.; Iavarone, C.; Trogolo, C.
Phytochemistry 1981, 20, 1587-1590.
(7) Skaltsounis, A. L.; Tillequin, F.; Koch, M.; Pusset, J .; Chauvie`re, G.
Planta Med. 1989, 55, 191-192.
(8) Crystallographic data for the structure reported in this paper have
been deposited with the Cambridge Crystallographic Data Centre
(deposition number CCDC 185135). Copies of the data can be
obtained, free of charge, on application to the Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: +44-(0)1223-336033 or
e-mail: depodit@ccdc.cam.ac.uk).
(9) (a) Sheldrick, G. M. SHELXS-90: A Program for Structure Determi-
nation; University of Go¨ttingen: Go¨ttingen, Germany, 1997. (b)
Sheldrick, G. M. SHELXL-97: A Program for Structure Refinement;
University of Go¨ttingen: Go¨ttingen, Germany, 1997.
Ack n ow led gm en t. The authors are grateful to Eun J ung
Bang for NMR at Korea Basic Science Institute (KSBI) and
Dr. Kwan Mook Kim for measurements of X-ray crystal-
NP020017Q