Total synthesis of two 12-nordrimanes and the pharmacological active sesquiterpene hydroquinone yahazunol

Article abstract of DOI:10.1016/j.tet.2004.11.059

The synthesis of two 12-nordrimanes and yahazunol was achieved via 8-oxo-12-nordrimanic acid methyl ester. The cytotoxic activity of yahazunol and seven other sesquiterpene hydroquinones and sesquiterpene quinones has been determined.

Full text of DOI:10.1016/j.tet.2004.11.059

Tetrahedron 61 (2005) 1141–1148
Total synthesis of two 12-nordrimanes and the pharmacological
active sesquiterpene hydroquinone yahazunol
Thorsten Laube,a Winfried Beilb and Karlheinz Seiferta,
*
a
¨ ¨
Lehrstuhl fur Organische Chemie, NW II, Universitat Bayreuth, D-95440 Bayreuth, Germany
b
¨
Institut fur Pharmakologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
Received 13 September 2004; revised 10 November 2004; accepted 18 November 2004
Available online 8 December 2004
Abstract—The synthesis of two 12-nordrimanes and yahazunol was achieved via 8-oxo-12-nordrimanic acid methyl ester. The cytotoxic
activity of yahazunol and seven other sesquiterpene hydroquinones and sesquiterpene quinones has been determined.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
2. Results and discussion
The both nordrimanes (C)-(8S)-12-nordrimane-8,11-diace-
tate ((C)-4) and (C)-11-hydroxy-12-nordrim-9-en-8-one
((C)-6) have been isolated from the marine sponge Dysidea
sp.1 (Fig. 1). Compound (C)-4 exhibited a weak inhibition
of the bioluminescence reaction of Photobacterium
leiognathi, a symbiotic luminous bacterium of tropical fish.1
According to the procedure of Furuichi et al.9 the racemate
of (G)-8-oxo-12-nordrimanic acid methyl ester ((G)-1)
was transformed with (2S,3S)-1,4-di-O-benzylthreitol to the
diastereomeric mixture of dioxolanes. Hydrogenolytic
splitting of the benzyl groups led to the diols, which could
be separated by silica gel MPLC. Hydrolysis of the both
dioxolanes with 2 N sulfuric acid in MeOH yielded (C)-1
and (K)-1. The keto group in position 8 of (K)-1 was
selectively reduced with NaBH4/CeCl3 to the hydroxy
function in (C)-2 (Scheme 1). In the second step the methyl
ester (C)-2 was reduced with DIBAH to the diol (C)-3. The
one pot reduction of (K)-1 to (C)-3 with NaBH4/CeCl3 and
DIBAH showed a better yield. Acetylation of (C)-3 with
acetyl chloride/pyridine gave (C)-(8S)-12-nordrimane-
8,11-diacetate ((C)-4).
The sesquiterpene hydroquinone yahazunol (11),2 zonarol
(12), zonarone (13), isozonarol (14), isozonarone (15),3
cyclozonarone (16),4 zonaroic acid and chromazonarol have
been obtained from the brown algae Dictyopteris undulata
Okamura.2 The compounds 12–16 and chromazonarol show
feeding-deterrent activity against the young abalone
Heliotis discus hannai.4 The sesquiterpene hydroquinones
and quinones 12–15, chromazonarol, zonaroic acid and
dictyochromenol possess toxicity against killifish.5
(C)-11-Hydroxy-12-nordriman-8-one ((C)-5) was
obtained as follows.9 The racemate of (G)-1 reacted with
(2R,3R)-2,3-butanediol to the both diastereomers which
were reduced with DIBAH to the diastereomeric alcohols.
These could be separated by silica gel MPLC. Hydrolysis of
both dioxolanes with Nafion NR 50 led to (C)-5 and (K)-5.
Pyridinium chlorochromate (PCC) oxidation of (C)-5 gave
in quantitative yield (C)-11-hydroxy-12-nordrim-9-en-8-
one ((C)-6) (Scheme 2).
Recently, we published the total syntheses of 11,6 12–16,6,7
spongiaquinone (17) and hyatellaquinone (18)8 starting
from (K)- and (C)-albicanal (Fig. 1).
In this paper, we describe the syntheses of the 12-
nordrimanes (C)-4, (C)-6 and yahazunol ((K)-11) starting
from (G)-8-oxo-12-nordrimanic acid methyl ester ((G)-1).
Our synthesis of the building block (G)-1 was reported
earlier.6 The marine sesquiterpene hydroquinones and
sesquiterpene quinones 11–18 were tested for their
cytotoxic activity.
The comparison of the optical rotations of (C)-(8S)-12-
nordrimane-8,11-diacetate ((C)-4) ([a]DZC72, MeOH)
and (C)-11-hydroxy-12-nordrim-9-en-8-one ((C)-6)
([a]DZC9.5, MeOH) with natural (C)-41 ([a]DZC36,
MeOH) and (C)-61 ([a]DZC9.6, MeOH) led to the
absolute configurations of the both nordrimanes. We assume
Keywords: Terpenes; Phenols; Quinones.
* Corresponding author. Tel.: C49 0921553396; fax: C49 0921555358;
e-mail: karlheinz.seifert@uni-bayreuth.de
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.11.059

1142
T. Laube et al. / Tetrahedron 61 (2005) 1141–1148
Figure 1. 12-Nordrimanes and pharmacologically tested sesquiterpene hydroquinones and sesquiterpene quinones.
that the determination of the optical rotation of natural 4 was
not correct. It is interesting that the two 12-nordrimanes
have been isolated from the same sponge Dysidea sp. but
their absolute configurations are different: (C)-4 (5S,10S),
(C)-6 (5R,10R).
Our first seven step synthesis of yahazunol ((K)-11) started
from (C)-albicanal. The change of the protecting group
tetrahydopyranyl (THP) to benzyl (Bn) in (C)-10
(Scheme 3) was a disadvantage of this route.6 For that
reason we used (C)-11-hydroxy-12-nordriman-8-one ((C)-
5) which was transformed with p-toluene sulfonic acid by
elimination of water to the enone (C)-7 (Scheme 3)
synthesized before starting from 12-nordrimane-8,11-
diol10,11 and (K)-7 from 11-hydroxy-12-nordriman-8-
one.12 The cuprate catalyzed conjugated 1,4-addition10 of
2,4-dibenzyloxyphenylmagnesium bromide to (C)-12-
nordrim-9-en-8-one ((C)-7) yielded the enolate anion
trapping with acetic anhydride. Treatment of the resulting
enolacetate (K)-8 with potassium hydroxide in methanol
afforded the ketone (C)-9. Wittig reaction of (C)-9 with
Ph3PCH2 gave (C)-zonarol dibenzyl ether (C)-10.
Scheme 1. Synthesis of (C)-(8S)-12-nordrimane-8,11-diacetat ((C)-4).
(a) NaBH4, CeCl3, THF/MeOH (2:1), room temperature, 30 min;
(b) DIBAH, CH2Cl2, room temperature, 30 min; (c) NaBH4, CeCl3, THF,
30 min; DIBAH, room temperature, 30 min; (d) AcCl, DMAP, Pyridin,
CH2Cl2, room temperature, 16 h.
Scheme 2. Synthesis of (C)-11-hydroxy-12-nordrim-9-en-8-one ((C)-6).
(a) PCC, CaCO3, CH2Cl2, room temperature, 20 min.

T. Laube et al. / Tetrahedron 61 (2005) 1141–1148
1143
Scheme 3. Synthesis of yahazunol ((K)-11). (a) PTS, benzene, 50 8C, 30 min; (b) CuI, 0 8C, 10 min, room temperature, 1 h; (c) Ac2O, 0 8C, room temperature,
20 min; (d) KOH, MeOH, room temperature, 6 h; (e) Ph3PCH2, THF, 80 8C, 48 h; (f) MCPBA, CH2Cl2, room temperature, 50 min; (g) LiAlH4, Et2O, reflux;
2 h; (h) H2, Pd/C, EtOH, 40 8C, 30 min.
yahazunol ((K)-11) could be improved from 54 to 61% by
heating the reaction mixture at 40 8C for 30 min.
Table 1. Cytoxic activity against the tumour cell lines L-929 (murine
fibroblasts), K-562 (human leukaemia) and HeLa (human cervix carci-
noma) of (C)-zonarol ((C)-12), (C)-zonarone ((C)-13), (C)-isozonarol
((C)-14) and (C)-isozonarone ((C)-15)
The sesquiterpene hydroquinones and sesquiterpene
quinones 11–18 (Fig. 1) were tested for their cytotoxic/
cytostatic activity.
Compound
L-929
K-562
HeLa
Zonarol ((C)-12)
2
2
2
1
2
2
2
2
2
1
2
1
Zonarol ((C)-12), zonarone ((C)-13) and isozonarol ((C)-
14) show a good cytotoxic activity against tumour cell lines
L-929 (murine fibroblasts) and K-562 (human leukemia)
and (C)-12, (C)-14 a good activity against the HeLa cell
line (human cervix carcinoma) (Table 1). The cytotoxic
Zonarone ((C)-13)
Isozonarol ((C)-14)
Isozonarone ((C)-15)
3, high activity; 2, middle activity; 1, low activity
¨
activity was determined at the Hans-Knoll-Institute in Jena
according to Ref. 13.
The overall yield leading to (C)-10 starting from (G)-8-
oxo-12-nordrimanic acid methyl ester ((G)-1) is 24% over
seven steps according to Scheme 3. The overall yield
starting from (G)-1 to (C)-10 of our first yahazunol
synthesis is 18% over 11 steps.6 The yields of the racemate
separations of (G)-1 and (G)-albicanic acid were con-
sidered as 50%. (C)-Zonarol dibenzyl ether ((C)-10) was
epoxidized in position 8, 12 with MCPBA. The oxirane ring
was opened with LiAlH4 to (C)-yahazunol dibenzyl ether
as described before.6 The yield of debenzylation of (C)-
yahazunol dibenzyl ether with H2 and Pd/C in EtOH to
(G)-Yahazunol ((G)-11), (G)-cyclozonarone ((G)-16),
(G)-spongiaquinone ((G)-17) and (G)-hyatellaquinone
((G)-18) were investigated for their cytostatic/cytotoxic
activity against the human tumour cell lines HM02 (gastric
adenocarcinoma), HepG2 (hepatocellular carcinoma) and
MCF 7 (breast carcinoma). (G)-Spongiaquinone ((G)-17)
possesses the highest cytostatic/cytotoxic activity (the
lowest GI50-value) against the cell lines HMO2 and
Table 2. Cytostatic/cytotoxic activity of (G)-yahazunol ((G)-11), (G)-cyclozonarone ((G)-16), (G)-spongiaquinone ((G)-17) and (G)-hyatellaquinone
((G)-18) against the tumour cell lines HM02 (gastric adenocarcinoma), HepG2 (hepatocellular carcinoma) and MCF 7 (breast carcinoma)
TGIb (mg/ml)
a
GI50 (mg/ml)
Compound
HM02
HepG2
MCF 7
HM02
HepG2
MCF 7
(G)-Yahazunol (G)-11
4.2
5.7
3.1
5.3
7.1
9.6
3.6
6.0
6.0
10.0
7.8
O10c
O10
95
(G)-Cyclozonarone (G)-16
(G)-Spongiaquinone (G)-17
(G)-Hyatellaquinone (G)-18
O10
2.6
2.4
O10
7.1
6.9
O10d
O10f
O10e
O10 g
a Drug concentration causing 50% growth inhibition.
b Drug concentration causing 100% growth inhibition.
c 70% inhibition at 10 mg/ml.
d 66% inhibition at 10 mg/ml.
e 52% inhibition at 10 mg/ml.
77% inhibition at 10 mg/ml.
f
g 64% inhibition at 10 mg/ml.

1144
T. Laube et al. / Tetrahedron 61 (2005) 1141–1148
Table 3. Cell cycle analysis of MCF 7 cells exposed to (G)-yahazunol ((G)-11), (G)-spongiaquinone ((G)-17) and (G)-hyatellaquinone ((G)-18)
Compound
SubG1-phase
G1-phase
S-phase
G2/M-phase
(G)-Yahazunol ((G)-11) (20 mg/ml)
(G)-Spongiaquinone ((G)-17) (40 mg/ml)
(G)-Hyatellaquinone ((G)-18) (40 mg/ml)
Control
16.8G2.7*
17.3G4.9*
23.5G3.6*
6.8G0.28
44.0G3.9*
44.0G2.4*
43.7G0.6*
61.0G0.8
13.4G3.6
21.7G1.0*
22.2G0.4*
16.0G1.6
29.0G3.0*
16.3G1.5
6.8G1.3*
15.6G0.7
Data represent percentage of cells in each stage of the cell cycle. Values are meanGSE of four experiments. *p!0.05 versus control (t test).
HepG2 and hyatellaquinone ((G)-18) against the cell line
MCF 7 (Table 2).
was added and stirring continued for 30 min. HCl (60 ml,
10%) and saturated NaCl-solution (20 ml) were added and
the mixture was extracted three times with ethyl acetate.
The combined organic layers were washed with saturated
KHCO3-solution and dried with Na2SO4. After filtration
through silica gel and removing the solvent further
purification was carried out by MPLC (LiChrospherw Si-
60 (15 mm); hexane/ethyl acetate 7:1, 20 bar, 30 ml/min) to
obtain (C)-2 (564 mg, 2.22 mmol, 56%) as colourless
crystals. Mp 164–165 8C (hexane/ethyl acetate). [a]2D5Z
C54 (c 1.00, CHCl3). Ref. 10: [a]2D4ZC53.8 (c 1.13,
CHCl3). IR (cmK1): 3522 (w), 3010 (m), 2954 (s), 2927 (s),
2871 (m), 2850 (m), 1743 (s), 1706 (s), 1459 (m), 1438 (m),
1348 (m), 1272 (w), 1258 (w), 1232 (w), 1196 (s). MS m/z
(%): 254 (17, MC%), 236 (39), 221 (94), 205 (13), 189 (10),
177 (19), 161 (61), 137 (100), 123 (95), 109 (80), 95 (85), 81
(89), 69 (87), 55 (73), 41 (89). HRMS: Calcd for C15H26O3
254.1882. Found 254.1882. 1H and 13C NMR: Tables 4 and 5.
The cell cycle analysis of MCF 7 cells exposed to (G)-
yahazunol ((G)-11), (G)-cyclozonarone ((G)-16), (G)-
spongiaquinone ((G)-17) and (G)-hyatellaquinone
((G)-18) led to the following results (Table 3): (G)-
yahazunol ((G)-11) locks the cells initially (as vincristine)
in the mitose phase (G2/M-phase) and induces apoptose.
(G)-Spongiaquinone ((G)-17) and (G)-hyatellaquinone
((G)-18) lock the cells initially (as 5-fluorouracil) in the
synthesis phase with replication of the DNA (S-phase).
This is connected with a decrease in the cell number in the
G1-phase. The apoptose of the cells is based on the blockade
of the DNA replication (increase in the cell number of the
SubG1-phase). (G)-Cyclozonarone ((G)-16) was investi-
gated in a broad concentration range. In each case, an
increase in apoptotic/necrotic cells was found. A lock of the
cell cycle in a specific cell phase could not be observed (data
are not given). In this way (G)-yahazunol ((G)-11), (G)-
spongiaquinone ((G)-17) and (G)-hyatellaquinone ((G)-
18) block the growth of tumour cells phase specific in the
G2/M- and S-phase.
3.2.2. (C)-(8S)-12-Nordrimane-8,11-diol ((C)-3). To a
solution of (C)-2 (470 mg, 1.85 mmol) in 10 ml of abs.
CH2Cl2 DIBAH (Aldrich, 1.0 M in abs. CH2Cl2, 7.4 ml,
7.4 mmol) was added dropwise. After 30 min the solution
was slowly poured into a mixture of 10 ml of concd HCl and
25 g of ice. The organic layer was separated and the aqueous
layer extracted two times with ethyl acetate. The combined
organic layers were washed with saturated KHCO3-
solution, saturated NaCl-solution and dried with Na2SO4.
After filtration through silica gel and removing the
solvent further purification was carried out by MPLC
(LiChrospherw Si-60 (15 mm); hexane/ethyl acetate 2:1,
20 bar, 30 ml/min) to yield (C)-3 (394 mg, 1.74 mmol,
94%) as colourless crystals. Mp 146–147 8C (hexane/ethyl
acetate). [a]D25Z C26 (c 1.00, CHCl3). Ref. 14: [a]2D3Z
C26.1 (c 0.93, CHCl3). IR (cmK1): 3500 (b), 2957 (s), 2925
(s), 2875 (m), 2847 (m), 2363 (w), 2330 (w), 1729 (m), 1457
(w), 1416 (m), 1389 (w), 1368 (w), 1334 (m), 1286 (w),
1160 (w). MS m/z (%): 226 (2, MC%), 208 (100), 193 (74),
175 (28), 165 (7), 152 (8), 149 (15), 137 (63), 123 (81), 109
(74), 95 (61), 81 (63), 69 (46), 55 (20), 41 (16). HRMS:
3. Experimental
3.1. General
All solvents were dried and purified prior to use. THF and
diethyl ether were dried by distillation from Na/K under Ar.
Flash chromatography: Merck silica gel 60, 0.040–
0.063 mm (230–400 mesh). MPLC: Bu¨chi B688 pump
and Bu¨chi B687 gradient former. IR: Perkin-Elmer 1420
Ratio Recording Spectrometer; solvent CHCl3. Optical
rotation values: JASCO Polarimeter P-1020 (589 nm). MS:
Finnigan MAT 8500 and Finnigan MAT SS 300; 70 eV.
NMR: Bruker Avance 300 and Bruker DRX 500, CDCl3/
CHCl3, acetone-D6/acetone and DMSO-D6/DMSO as
internal standards.
Calcd for C14H26O2 226.1933. Found 226.1933. 1H and 13
NMR: Tables 4 and 5.
C
For TLC runs, precoated silica-gel foils 60 F254 (5!10 cm2)
from Merck were used. Spots were visualised by irradiation
under UV lamp or by treatment with phosphomolybdic acid
test spray.
3.2.3. (C)-(8S)-12-Nordrimane-8,11-diol ((C)-3)
directly from (K)-1. To a solution of CeCl3 (0.4 M,
40 mmol) in THF (100 ml) (K)-1 (1.00 g, 3.96 mmol) was
added and stirred for 15 min. NaBH4 (650 mg, 17.2 mmol)
was added and stirring continued for 30 min. DIBAH
(Aldrich, 1.0 M in abs. CH2Cl2, 16 ml, 16 mmol) was added
dropwise. After 30 min the solution was slowly poured into
a mixture of 30 ml of concd HCl and 75 g of ice. Further
procedure is the same as described under Section 3.2.2 and
yielded (C)-3 (672 mg, 2.97 mmol, 75%).
3.2. Preparation, physical and spectroscopic data of the
compounds
3.2.1. (C)-(8S)-8-Hydroxy-12-nordrimanic acid methyl
ester ((C)-2). To a solution of CeCl3 (0.4 M, 40 mmol) in
THF/MeOH (100 ml, 2:1) (K)-1 (1.00 g, 3.96 mmol) was
added and stirred for 15 min. NaBH4 (650 mg, 17.2 mmol)

1
Table 4. H NMR data of compounds (C)-2, (C)-3, (C)-4, (C)-6, (C)-7, (K)-8, (C)-9, (C)-10 and (K)-11
Position
1
(C)-2a (CDCl3)
(C)-3a (D.-D6)
(C)-4a (CDCl3)
(C)-6a (CDCl3)
(C)-7a (CDCl3)
(K)-8b (CDCl3)
(C)-9b (CDCl3)
(C)-10a (CDCl3)
(K)-11a (A.-D6)
1.06
1.31
1.27
1.47
1.05
1.28
0.93
1.67
1.36
1.48
1.12
1.35
1.01 dd (13.1/3.5) 1.27
1.69
1.37
1.56
1.13
1.37
0.88
1.39
1.47
1.45
1.95
5.10 ddd (3.4)
1.51
3.99 d (10.7)
4.11 dd (10.7/3.8)
—
1.42
1.75
1.52
1.57
1.19
1.46
1.38
1.60
1.74
2.23
2.65
—
0.90
1.61
1.28
1.61
1.01
1.61
1.21
1.42
1.01
1.73
1.41
1.55
1.10
1.32
1.10
1.30
1.73
1.95
2.32
—
0.72 dd (17.9/4.4)
1.84
1.34
1.62
1.11
1.33
0.94
1.34
2.01
1.53
1.58
1.17
1.41
1.14
1.55
1.77
2.41
2.45
—
2
3
1.07 dd (13.2/4.4) 1.01
1.28
1.19
1.68
1.79
1.35
1.34
1.61
1.98
5
6
0.82 dd (12.3/2.0) 0.82
1.36
1.56
1.30
1.88
3.99
2.07 d (2.2)
—
1.37
1.56
1.38
1.79
3.53
0.98
4.04
1.66
1.57
7
2.17 dd (17.0/6.2) 2.15
2.45
—
2.31
—
2.49 d (9.4)
2.69 dd (13.1/1.7) 2.73
2.85 dd (13.1/9.4) 2.81
—
1.92 dd (16.9/4.0)
—
1.57
2.40 dd (20.7/8.5)
2.85 dd (20.7/2.7)
1.30 s
8
9
11
—
8.59 d (4.4)
—
—
2.23
4.97 d (1.2)
5.50 d (1.2)
—
3.31
3.33
—
12
—
—
—
4.63
4.72
13
14
0.77 s
0.74 s
1.08 s
—
—
—
—
—
—
—
—
—
—
3.80 br s
—
0.83 s
0.79 s
0.91 s
—
—
—
—
—
—
—
—
—
—
3.50
3.97
—
0.83 s
0.81 s
0.97
—
—
—
—
—
—
—
0.89 s
0.83 s
1.13 s
—
—
—
—
—
—
—
—
—
0.93 s
0.98 s
0.89 s
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0.91 s
0.82 s
1.00 s
—
—
6.79 d (8.8)
6.71 dd (8.8/3.0)
—
6.81 d (3.0)
5.04
5.02
1.91 s
—
—
—
0.91 s
0.81 s
0.73 s
—
—
6.78 d (8.8)
6.71 dd (8.8/3.0)
—
7.04 d (3.0)
4.96
4.99
—
—
—
—
—
0.86 s
0.80 s
0.76 s
—
—
6.78 d (8.7)
6.68 dd (8.7/2.8)
—
6.81 d (2.8)
4.97
5.01
0.86 s
0.83 s
0.97 s
—
—
6.53 d (8.5)
6.49 dd (8.5/2.7)
—
6.64 d (2.7)
—
—
—
—
—
—
—
—
15
10
20
30
40
50
60
C20OCH2
C50OCH2
Ac (8)
Ac (11)
OH
—
1.98 s
2.00 s
—
—
—
—
15.37 d (4.4)
—
—
—
OH
Me
Benzyl
3.57 s
—
—
7.43—7.24
—
—
7.46—7.25
7.44—7.30
Coupling constants J in Hz. A.-D6, acetone-D6; D.-D6, DMSO-D6.
a Bruker DRX 500 spectrometer.
b Bruker AC 300 spectrometer.

Table 5. 13C NMR data of compounds (C)-2, (C)-3, (C)-4, (C)-6, (C)-7, (K)-8, (C)-9, (C)-10 and (K)-11
Position
(C)-2a (CDCl3)
(C)-3a (D.-D6)
(C)-4a (CDCl3)
(C)-6a (CDCl3)
(C)-7a (CDCl3)
(K)-8b (CDCl3)
(C)-9b (CDCl3)
(C)-10a (CDCl3)
(K)-11a (A.-D6)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
40.1
17.9
41.7
33.1
55.1
16.6
33.0
67.4
58.6
37.7
175.7
—
33.3
21.3
16.5
—
—
—
—
—
—
—
—
—
—
—
39.3
18.0
41.7
32.9
55.4
16.9
35.2
64.5
56.2
36.7
57.4
—
33.6
21.7
16.5
—
—
—
—
—
—
—
—
—
—
—
39.3
18.2
41.7
33.1
55.1
17.2
31.4
69.1
51.4
36.9
60.9
—
33.6
21.6
15.9
—
—
—
—
—
—
—
—
—
—
21.3
21.0
170.5
171.3
—
38.0
18.7
41.2
32.8
50.0
17.5
32.6
188.6
122.5
35.0
183.0
—
33.0
21.1
24.8
—
—
—
—
—
—
—
—
—
—
—
37.7
18.7
41.8
33.7
50.5
20.6
40.8
204.2
159.0
40.5
113.5
—
33.5
21.5
21.0
—
—
—
—
—
—
—
—
—
—
—
35.8
18.7
41.4
33.2
51.1
18.7
28.0
144.9
132.1
38.6
24.3
—
33.2
21.7
20.4
130.7
150.1
112.5
112.9
152.8
115.9
70.8
70.2
137.6c
137.7c
20.9
—
38.6
18.9
41.8
33.6
54.1
24.1
42.6
211.6
63.9
43.1
23.2
—
33.5
21.6
14.5
131.8
151.0
112.5
112.0
152.5
118.9
70.9
70.4
137.2
137.5
—
38.9
19.4
42.1
33.6
55.6
24.4
38.3
148.4
55.7
39.9
24.0
107.6
33.7
21.7
14.5
132.5
152.7
112.5
111.2
151.1
117.6
70.9
70.5
137.5
137.4
—
41.4
19.1
42.6
33.8
57.0
21.2
44.6
75.1
62.4
40.6
28.0
24.6
33.9
21.9
15.9
131.2
149.7
117.4
114.3
150.4
118.9
—
15
10
20
30
40
50
60
C20OCH2
C50OCH2
C20Bn 1
C50Bn 1
Ac (8)
Ac (11)
CO (8)
CO (11)
Me
—
—
—
—
—
—
—
—
—
—
—
51.0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
128.4
128.3
128.2
128.0
127.7
127.5
—
—
—
—
128.5
128.4
127.8
127.7
127.6
127.5
169.2
—
—
Benzyl
—
—
—
—
127.7
127.6
127.3
127.2
—
A.-D6, acetone-D6; D.-D6, DMSO-D6.
a Bruker DRX 500 spectrometer.
b Bruker AC 300 spectrometer.
c Signals are exchangeable.

T. Laube et al. / Tetrahedron 61 (2005) 1141–1148
1147
3.2.4. (C)-(8S)-12-Nordrimane-8,11-diacetate ((C)-4).
To a solution of (C)-3 (149 mg, 0.66 mmol) in abs.
CH2Cl2 (10 ml) DMAP (20 mg), abs. pyridine (1 ml,
12 mmol) and AcCl (0.85 ml, 10 mmol) were added. After
16 h MeOH (1 ml) was added and stirring continued for
30 min. The solution was filtered through silica gel and
purified using MPLC (LiChrospherw Si-60 (15 mm);
hexane/ethyl acetate 6:1, 20 bar, 30 ml/min) to get (C)-4
(172 mg, 0.55 mmol, 84%) as colourless crystals. Mp 84–
85 8C (hexane/ethyl acetate). [a]2D4ZC72 (c 1.00, MeOH).
Ref. 1: [a]2D5ZC36.0 (c 0.20, MeOH). IR (cmK1): 2954 (s),
2934 (s), 2871 (m), 2850 (m), 1729 (s), 1459 (m), 1438 (w),
1390 (m), 1369 (m), 1265 (s), 1155 (w), 1125 (w), 1025 (m).
MS m/z (%): 310 (2, MC%), 267 (15), 250 (8), 235 (6), 207
(61), 190 (100), 175 (76), 147 (38), 137 (49), 136 (71), 109
(54), 95 (48), 69 (36), 55 (14), 43 (56). HRMS: Calcd for
solution of (C)-7 (620 mg, 3.0 mmol) in THF (10 ml) was
added to the above cuprate reagent, stirred for 15 min at
0 8C and then 1 h at room temperature. After cooling to 0 8C
Ac2O (2 ml, 21.8 mmol) was added to the mixture and
stirring was continued for 20 min at room temperature. The
reaction mixture was diluted with saturated NH4Cl-solution
and saturated NaHCO3-solution, extracted with t-butyl
methyl ether and the organic layer was separated. The
aqueous layer was extracted two times with ethyl acetate,
the combined organic layers were washed with saturated
NaCl-solution and dried with Na2SO4. After filtration
through silica gel and removing the solvent further
purification was carried out by MPLC (LiChrospherw Si-
60 (15 mm); hexane/ethyl acetate 12:1, 20 bar, 30 ml/min)
to get (K)-8 (1374 mg, 2.55 mmol, 85%) as a colourless oil.
[a]2D3ZK4 (c 0.80, CHCl3). IR (cmK1): 3030 (s), 2915 (m),
1747 (s), 1505 (m), 1235 (w), 1200 (m), 1020 (w). MS m/z
(%): 538 (2, MC%), 495 (14), 91 (100), 43 (36). HRMS:
1
C18H30O4 310.2144. Found 310.2144. H and 13C NMR:
Tables 4 and 5.
Calcd for C36H42O4 538.3083. Found 538.3087. 1H and 13
NMR: Tables 4 and 5.
C
3.2.5. (C)-11-Hydroxy-12-nordrim-9-en-8-one ((C)-6).
Pyridinium chlorochromate (1.44 g, 6.7 mmol) and CaCO3
(0.65 g, 6 mmol) were stirred for 15 min in 30 ml of abs.
CH2Cl2. A solution of (C)-5 (100 mg, 0.45 mmol) was
added. The reaction was monitored until the educt has
completely disappeared (20 min). The mixture was filtered
through a short silica gel column (10 cm) to separate the
chromium salts. Removing the solvent in vacuo at room
temperature gave (C)-6 (99 mg, 0.45 mmol, 99%) as
colourless crystals. Mp 79–80 8C (CH2Cl2), [a]2D3ZC9.5
(c 0.95, MeOH). Ref. 1: [a]2D5ZC9.6 (c 0.10, MeOH). IR
(cmK1): 3500 (s), 2930 (s), 2870 (m), 1620 (s), 1590 (s),
1460 (m), 1380 (m), 1290 (w), 1200 (m), 940 (w). MS m/z
(%): 222 (13, MC%), 207 (100), 189 (18), 179 (60), 137 (11),
69 (17), 41 (19). HRMS: Calcd for C14H22O2 222.1619.
3.2.8. (C)-11-(20,50-Dibenzyloxyphenyl)-8-oxo-12-nor-
drimane ((C)-9). A mixture of (K)-8 (1.8 g, 3.34 mmol)
and KOH (4.0 g) in MeOH (40 ml) was stirred at room
temperature for 6 h. The reaction mixture was diluted with
saturated NaCl-solution, extracted with t-butyl methyl ether
and the organic layer was separated. The aqueous layer was
extracted two times with ethyl acetate, the combined
organic layers were washed with saturated NaCl-solution
and dried with Na2SO4. After filtration through silica gel
and removing the solvent further purification was carried
out by MPLC (LiChrospherw Si-60 (15 mm); hexane/ethyl
acetate 12:1, 20 bar, 30 ml/min) to yield (C)-9 (1593 mg,
3.21 mmol, 96%) as a colourless oil. [a]2D4ZC7 (c 0.90,
CHCl3). IR (cmK1): 3035 (s), 2925 (m), 1709 (s), 1485 (m),
1255 (w), 1190 (m), 1020 (w). MS m/z (%): 496 (1, MC%),
332 (10), 91 (100), 65 (13). HRMS: Calcd for C34H40O3
1
Found 222.1621. H and 13C NMR: Tables 4 and 5.
3.2.6. (C)-12-Nordrim-9-en-8-one ((C)-7). To a solution
of (C)-5 (400 mg, 1.78 mmol) in benzene (50 ml) p-toluene
sulfonic acid (50 mg, 0.26 mmol) was added and the
mixture was stirred for 30 min at 50 8C. Saturated
Na2CO3-solution was added, the organic layer was separ-
ated and the aqueous layer extracted two times with ethyl
acetate. The combined organic layers were washed with
saturated NaCl-solution and dried with Na2SO4. After
filtration through silica gel and removing the solvent further
purification was carried out by MPLC (LiChrospherw Si-60
(15 mm); hexane/ethyl acetate 20:1, 20 bar, 30 ml/min) to
obtain (C)-7 (341 mg, 1.65 mmol, 93%) as a colourless oil.
[a]D24ZC70 (c 1.00, CHCl3). Ref. 10: [a]2D3ZC71.9 (c
0.69, CHCl3). IR (cmK1): 3095 (s), 2950 (m), 2930 (m),
2870 (m), 2845 (s), 1700 (s), 1610 (m), 1460 (m), 1415 (m),
1380 (w), 1300 (w), 1280 (m), 1240 (w), 1200 (m), 1175
(m), 1100 (w), 1060 (w), 1040 (w). MS m/z (%): 206 (100,
1
496.2977. Found 496.2979. H and 13C NMR: Tables 4
and 5.
3.2.9. (C)-Zonarol dibenzyl ether ((C)-10). n-BuLi
(1.8 ml, 2.88 mmol) was added to a suspension of Ph3-
PCMeBrK (1.37 g; 5.76 mmol) in THF (40 ml) at K78 8C
under argon and the mixture was stirred for 30 min. A
solution of (C)-9 (790 mg; 2.28 mmol) in THF (5 ml) was
added. After stirring at 80 8C for 48 h the reaction mixture
was diluted with saturated NaCl-solution (20 ml) and
extracted with t-butyl methyl ether. The organic layer was
washed with H2O and dried with Na2SO4. After filtration
through silica gel and removing the solvent further
purification was carried out by MPLC (LiChrospherw Si-
60 (15 mm); pentane/Et2O 25:1, 20 bar, 30 ml/min) to get
(C)-10 (846 mg, 1.71 mmol, 75%) as colourless crystals.
Mp 110–111 8C (pentane/Et2O). [a]2D3ZC18 (c 1.00,
CHCl3). IR (cmK1): 3020 (s), 2930 (m), 1495 (m), 1227
(m), 1205 (w), 1024 (w). MS m/z (%): 494 (72, MC%), 403
(6), 213 (8), 137 (7), 123 (8), 91 (100). HRMS: Calcd for
M
C%), 191 (72), 69 (9), 55 (10). HRMS: Calcd for C14H22O
206.1670. Found 206.1678. 1H and 13C NMR: Tables 4 and 5.
3.2.7. (K)-11-(20,50-Dibenzyloxyphenyl)-12-nordrim-8,9-
en-8-yl acetate ((K)-8). A mixture of Mg (320 mg,
13 mmol) and 2-bromo-1,4-hydroquinone dibenzyl ether
(4.42 g, 12 mmol) in THF (75 ml) was refluxed for 2.5 h
under argon. The generated Grignard reagent was added
dropwise to CuI (30 mg, 3.83 mmol) at 0 8C under argon
and the whole mixture was stirred at 0 8C for 10 min. A
1
C35H42O2 494.3185. Found 494.3184. H and 13C NMR:
Tables 4 and 5.
The synthesis of 8,12-epoxyzonarol dibenzyl ether, (C)-
yahazunol dibenzyl ether and yahazunol ((K)-11) was

1148
T. Laube et al. / Tetrahedron 61 (2005) 1141–1148
1
described before.6 The H and 13C NMR data of (K)-11
were given in Tables 4 and 5.
Forschungsgemeinschaft (Se-595/9-1) is gratefully
acknowledged. We thank Dr. Ernst Roemer from the
¨
Hans-Knoll-Institute in Jena for the determination of the
cytotoxic activity of compounds 12–15.
3.3. Determination of the pharmacological activity
3.3.1. Test for cytostatic/cytotoxic activity. The investi-
gations were carried out according to the NCI guidelines
with the tumour cell lines HMO2, HepG2 and MCF 7. The
cells were cultivated in RPMI 1640 medium with 10% fetal
bovine serum on 96-well microtiter plates. After sowing the
test samples (24 h) (concentrations: 0.1, 0.5, 1.0, 5.0,
10.0 mg/ml) were added and the cells were cultivated for
further 48 h. The cell number was obtained by protein
determination with sulforhodanine. The test samples were
dissolved in MeOH. The MeOH concentration in the test
was 0.1%. The concentration activity curves led to the
following values: GI50Zconcentration which produces a
half maximum inhibition of the cell growth; TGIZ
concentration which produces a complete inhibition of the
cell growth.
References and notes
1. Paul, V. J.; Seo, Y.; Cho, K. W.; Rho, J.-R.; Shin, J.; Bergquist,
P. R. J. Nat. Prod. 1997, 60, 1115–1120.
2. Ochi, M.; Kotsuki, H.; Muraoka, K.; Tokoroyama, T. Bull.
Chem. Soc. Jpn 1979, 52, 629–630.
3. Fenical, W.; Sims, J. J.; Sqatrito, D.; Wing, R. M.; Radlick, P.
J. Org. Chem. 1973, 38, 2383–2386.
4. Kurata, K.; Taniguchi, K.; Suzuki, M. Phytochemistry 1996,
41, 749–752.
5. Dave, M.-N.; Kusumi, T.; Ishitsuka, M.; Iwashita, T.;
Kakisawa, H. Heterocycles 1984, 22, 2301–2307.
¨
6. Laube, T.; Schroder, J.; Stehle, R.; Seifert, K. Tetrahedron
3.3.2. Cell cycle analysis. Cell cycle distribution was
determined by staining DNA with propidium iodide. Cells
were treated for 24 h with indicated concentrations of each
drug, harvested by trypsination, washed with RPMI 1640
containing 1% fetal bovine serum and resuspended in 125 ml
of a solution containing 150 mg/ml propidium iodide, 1%
Triton X-100, 1% bovine serum albumin and 4 mM sodium
citrate buffer, pH 7.4. After 15 min incubation at room
temperature under light exclusion, the same volume of
RNase A (10 mg/ml in 10 mM Tris and 15 mM NaCl,
pH 7.4) was added and cells were incubated for additional
30 min at room temperature. At the end of incubation period
cells were analyzed using a Becton Dickinson FACSscan
and Lysis II software.
2002, 58, 4299–4309.
¨
7. Schroder, J.; Matthes, B.; Seifert, K. Tetrahedron Lett. 2001,
42, 8151–8152.
¨
8. Bernet, A.; Schroder, J.; Seifert, K. Helv. Chim. Acta 2003, 86,
2009–2020.
9. Furuichi, N.; Hata, T.; Soetjipto, H.; Kato, M.; Katsumura, S.
Tetrahedron 2001, 57, 8425–8442.
10. Mori, K.; Komatsu, M. Bull. Soc. Chim. Belg. 1986, 95,
771–781.
11. Akita, H.; Nozawa, M.; Shimizu, H. Tetrahedron: Asymmetry
1998, 9, 1789–1799.
´
12. Pena, W.; Lopez, J. T.; Cortes, M. Synth. Commun. 1989, 16,
´
2841–2850.
¨
13. Dahse, H.-M.; Schlegel, B.; Grafe, U. Pharmazie 2001, 56,
489–491.
Acknowledgements
14. Toshima, H.; Oikawa, H.; Toyomasu, T.; Sassa, T.
Tetrahedron 2000, 56, 8443–8450.
Support of this research by a grant of the Deutsche