Synthesis of non-THF analogs of acetogenin toward simplified mimics

Article abstract of DOI:10.1016/j.tetlet.2005.05.150

Acetogenin analogs in which the bis-adjacent THF ring was replaced with an enantioselectively synthesized 1,2-cyclopentanediol bis-ether skeleton were synthesized to obtain simplified mimics, and their inhibitory effect on mitochondrial NADH-ubiquinone oxidoreductase (complex I) was examined. The results clearly demonstrate that the 1,2-cyclopentanediol bis-ether motif can substitute for the bis-THF ring while maintaining very potent inhibitory activity at the nanomolar level.

Full text of DOI:10.1016/j.tetlet.2005.05.150

Tetrahedron
Letters
Tetrahedron Letters 46 (2005) 5775–5779
Synthesis of non-THF analogs of acetogenin toward
simplified mimics
Daisuke Fujita, Naoya Ichimaru, Masato Abe, Masatoshi Murai, Takeshi Hamada,
Takaaki Nishioka and Hideto Miyoshi*
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
Received 27 April 2005; revised 16 May 2005; accepted 20 May 2005
Available online 6 July 2005
Abstract—Acetogenin analogs in which the bis-adjacent THF ring was replaced with an enantioselectively synthesized 1,2-cyclo-
pentanediol bis-ether skeleton were synthesized to obtain simplified mimics, and their inhibitory effect on mitochondrial NADH–
ubiquinone oxidoreductase (complex I) was examined. The results clearly demonstrate that the 1,2-cyclopentanediol bis-ether motif
can substitute for the bis-THF ring while maintaining very potent inhibitory activity at the nanomolar level.
ꢀ 2005 Elsevier Ltd. All rights reserved.
1. Introduction
Wu and co-workers have developed a series of aceto-
genin mimics in which the bis-adjacent THF ring and
flanking OH groups were replaced with an ethylene gly-
col bis-ether unit and all chiral centers of the THF
region were eliminated, namely ꢀlinear mimicsꢁ.3 These
analogs with simplified structures elicited fairly potent
cytotoxicity against several tumor cell lines, being nearly
equipotent with adriamycin.4 One of the analogs (i.e.,
AA005) was shown to inhibit mitochondrial complex I
at a sufficiently high concentration.3e It is however
unclear whether the potent inhibitory effect on mito-
chondrial complex I can be retained with this kind of
drastic structural simplification since cytotoxicity assays
have to take into consideration factors such as mem-
brane transport, intracellular transport and metabolic
inactivation. Actually, in Ref. 3a, it seems to be some-
what confusing that bullatacin, one of the most potent
acetogenins so far reported,1 showed rather lower cyto-
toxicity than the mimics. Furthermore, since no natural
acetogenin was investigated as a control in related
reports,3b,c,d one cannot directly compare the changes
in the cytotoxicity of the mimics. It should be noted that
similar structural simplification by another research
Acetogenins isolated from the plant family Annonaceae
have potent and diverse biological effects such as anti-
tumor, antimalarial, pesticidal, and antifeedant activities.1
The inhibitory effect of acetogenins on mitochondrial
NADH–ubiquinone oxidoreductase (complex I) is of
particular importance since their diverse biological activ-
ities are thought to be attributable to this effect.1 Their
structures are characterized by an a,b-unsaturated c-lac-
tone ring, one to three tetrahydrofuran (THF) ring(s)
with flanking OH group(s), an alkyl spacer linking the
c-lactone and THF, and a long alkyl tail. These unique
structural features and multiple chiral centers, especially
more than four chiral centers in the THF portion, make
them challenging synthetic targets. A number of total
synthesis of acetogenins has been reported since 1990s.2
However, all methods reported to date require at least
about 20 reaction steps. Structural simplification while
maintaining all the essential functionalities of aceto-
genins may reduce the task of synthesizing a variety of
acetogenin mimics, which can be used to probe the struc-
tural and functional features of mitochondrial complex I.
5
groupresulted in a drastic decrease in cytotoxicity.
In the present study, we remarked a structural similarity
between the hydroxylated bis-THF skeleton of natural
acetogenins and the hydroxylated 1,2-cyclopentanediol
bis-ether motif, especially the relative spatial position
of four oxygen atoms as illustrated in Figure 1. To
examine whether the latter can substitute for the former
Keywords: Acetogenin; Structure–activity relationship; Mitochondrial
complex I.
*
Corresponding author. Tel.: +81 75 753 6119; fax: +81 75 753
6408; e-mail: miyoshi@kais.kyoto-u.ac.jp
0040-4039/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2005.05.150

5776
D. Fujita et al. / Tetrahedron Letters 46 (2005) 5775–5779
while maintaining a potent inhibitory effect on complex
OH
OH
OH
OH
O
O
I, we synthesized acetogenin mimics, wherein the bis-
THF skeleton was replaced with an enantioselectively
synthesized 1,2-cyclopentanediol bis-ether unit (Fig. 2),
and examined their inhibitory activities using bovine
heart mitochondrial complex I.
O
O
OH
OH
OH
OH
O
O
O
O
2. Results and discussion
Superimposition
The synthetic procedures for the construction of the 1,2-
cyclopentanediol bis-ether moiety are outlined in
Scheme 1. ( )-trans-1,2-Cyclopentanediol was acetyl-
ated to give mono- and diacetates (6 and 7, respec-
tively). Racemic monoacetate 6 was subjected to
enantioselective hydrolysis by Pseudomanas fluorescens
lipase (Amano AK, Wako Pure Chemical Ind., Ltd) in
vinyl acetate6 to afford compound 8a. The optical rota-
tion of 8a was in good agreement with that of known
Figure 1. Superimposition of the hydroxylated bis-THF and the
hydroxylated 1,2-cyclopentanediol bis-ether skeletons.
S
O
R
HO
threo
O
trans
trans
O
26
22
sample (½aꢀ +30.7, c 1.3, CH3CN; lit.7 ½aꢀ +29.2, c
threo
threo
Natural-type Acetogenin (1)
D
D
O
1.0, CH3CN). The optical purity was determined after
conversion of 8a into 10a, which was prepared by
MOM ether protection of 8a and the hydrolysis of the
resultant acetate 9a.8 Mitsunobu inversion of alcohol
10a using diethyl azodicarboxylate (DEAD), TPP, and
p-nitrobenzoic acid and subsequent hydrolysis provided
compound 11a.8 The optical purities of 10a (>98% ee)
and 11a (>98% ee) were determined by 1H NMR analy-
ses of the corresponding (R)-MTPA esters. The 1H
NMR spectra showed a clear resolution of the a-meth-
oxy (d 3.54 and 3.61 for 10a and 11a, respectively) and
MOM methyl (d 3.31 and 3.35) protons.
HO
R
S
O
R
HO
O
O
O
A
B
Simplified Mimics
HO
R
(A-R, B-R) : Compound 2
(A-R, B-S) : Compound 3
(A-S, B-R) : Compound 4
(A-S, B-S) : Compound 5
On the other hand, diacetate 7 was subjected to enantio-
selective hydrolysis by P. fluorescens lipase (Amano AK,
Wako Pure Chemical Ind., Ltd) in 100 mM potassium
phosphate buffer (pH 7.0)6 at 26 ꢁC to afford compound
8b. The specific rotation of 8b was in good agreement
Figure 2. Structures of natural-type acetogenin and its simplified
mimics synthesized in this study.
26
D
with the reported value (½aꢀ ꢁ27.3, c 1.4, CH3CN;
OH
OH
OAc
OAc
a
+
OH
(trans, racemic)
S
OAc
6
7
(trans, racemic)
(trans, racemic)
S
S
S
OH
OMOM
OAc
OMOM
OH
OMOM
OH
b
c
e
d
6
7
OAc
S
S
S
R
8a
11a (S, R)
[α]D26 +27.5 (c 1.1, CH2Cl2)
9a
10a (S, S)
[α]D26 +96.3 (c 1.5, CH2Cl2)
R
R
R
R
OH
OMOM
OAc
OMOM
OMOM
c
e
f
d
OAc
OH
OH
R
R
R
S
8b
9b
10b (R, R)
[α]D26 -100.0 (c 1.0, CH2Cl2)
11b (R, S)
[α]D26 -28.0 (c 1.0, CH2Cl2)
Scheme 1. Reagents and conditions: (a) acetic anhydride (10 equiv), YbCl3, THF, rt, 1 day, 6 (53%), 7 (44%); (b) lipase Amano AK, vinyl acetate, rt,
1 day, 40%; (c) MOMCl, (i-Pr)2NEt, CH2Cl2, rt, 1 day, 97%; (d) K2CO3, MeOH, 40 ꢁC, 1 h, 89%; (e) (i) DEAD, Ph3P, p-NO2C6H4COOH, toluene,
80 ꢁC, 1 h, 86%, (ii) K2CO3, MeOH, 40 ꢁC, 1 h, 99%; (f) lipase Amano AK, 100 mM potassium phosphate buffer (pH 7.0), rt, 1 day, 48%.

D. Fujita et al. / Tetrahedron Letters 46 (2005) 5775–5779
5777
22
D
lit.7 ½aꢀ ꢁ28.2, c 1.0, CH3CN). Compounds 10b and
provided enyne 19. Since selective hydrogenation of 19
with Wilkinsonꢁs catalyst resulted in appreciable
reduction of the butenolide double bond as pointed
out by Marshall and Chen,14 hydrogenation was carried
out with diimide, generated in situ from tosylhydr-
azine,15 to obtain 3.16 Compounds 2, 4, and 5 were
synthesized by the same method starting from the corre-
sponding enantiomerically pure alcohols.16 All final
products were purified by a preparative HPLC (Wako-
sil-II 5C18HG, 20 · 250 mm) to separate a trace amount
of byproducts in which the butenolide double bond was
reduced and/or the spacer portion is still partially
unsaturated.
11b were synthesized by the same procedures as
described above in the enantiomerically pure form
(>98% ee, from the 1H NMR spectra of the correspond-
ing (R)-MTPA esters).8
Construction of the entire acetogenin molecule was
performed according to a procedure similar to that
reported,9 as outlined in Scheme 2 taking the (R,S)
derivative (11b) as an example. The structural features
other than the bis-THF ring portion were set to be same
as those of the synthetic acetogenin (1) since the inhibi-
tory potency of 1 is identical to that of the most potent
natural acetogenins like bullatacin.10 Reaction of the
alkoxide of 11b with (2R)-glycidyl tosylate gave a 97:3
mixture of the desired 12 and its epimer wherein the
glycidyl configuration was inversed due to initial epox-
ide attack by the alkoxide followed by extrusion of tos-
ylate.11 These isomers could be separated by
chromatography on silica gel after conversion to the
benzyl derivative 14. Opening of epoxide 12 with
1-lithio-1-nonyne in the presence of BF3 etherate12 pro-
vided 13. Protection of the alcohol by benzyl ether and
subsequent deprotection of MOM ether gave 14. Reac-
tion of the alkoxide of 14 with (2R)-glycidyl tosylate
gave a 95:5 mixture of the desired 15 and its epimer as
described above. The diastereomers were separable after
conversion to the alcohol 16 that was obtained by the
reaction of 15 with lithium TMS acetylide in the pres-
ence of BF3 etherate. Deprotection of the benzyl ether
of 16 was achieved by treatment with 2,3-dichloro-5,6-
dicyano-1,4-benzoquinone (DDQ) in CH2Cl2/H2O
(20:1) at room temperature without saturation of the tri-
ple bonds. Pd(0)-catalyzed coupling of alkyne 17 with
vinyl iodide 18, which was prepared as described,13
We examined the inhibitory activities of the acetogenin
mimics synthesized in this study against bovine heart
mitochondrial complex I according to the method
described previously (Table 1).17 All the test compounds
(2–5) elicited very potent inhibition at the nanomolar
level, being nearly equipotent with bullatacin. No
Table 1. Summary of the inhibitory potencies (IC50) of the test
compoundsa
Compounds
IC50 (nM)
1
0.83 ( 0.03)
1.9 ( 0.06)
1.0 ( 0.04)
1.4 ( 0.04)
0.90 ( 0.03)
0.85 ( 0.03)
2
3
4
5
Bullatacin
a The IC50 value is the molar concentration needed to reduce the
control NADH oxidase activity (0.60–0.65 lmol NADH/min/mg of
protein) in submitochondrial particles by half. Values are
means SD of three independent experiments.
O
R
OMOM
O
OMOM
O
OH
O
O
O
R
S
OMOM
OH
c
a
a
b
O
R
R
TsO
R
O
OH
C7H15
OBn
C7H15
OBn
C7H15
11b
12
13
14
15
O
OH
TMS
OH
H
OH
O
5
R
f
R
O
O
O
O
O
d
e
g
3
S
O
O
S
I
C7H15
R
7
O
OBn
C7H15
OH
OH
C7H15
18
19
17
16
Scheme 2. Reagents and conditions: (a) NaH, THF/DMF (1:1), rt, 1 h, then (2R)-glycidyl tosylate, rt, 6 h, 85%; (b) 1-nonyne, n-BuLi, BF3ÆEt2O,
THF, ꢁ78 ꢁC, 15 min, 91%; (c) (i) BnBr, NaH, THF/DMSO (1:1), rt, 1 day, 88%, (ii) 3% AcCl (in MeOH), CH2Cl2, 40 ꢁC, 3 h, 87%; (d) TMS–
acetylene, n-BuLi, BF3ÆEt2O, THF, ꢁ78 ꢁC, 15 min, 65%; (e) (i) DDQ, CH2Cl2/H2O (20:1), rt, 1 day, 70%, (ii) K2CO3, MeOH, rt, 1 h, 95%; (f)
Pd(Ph3P)4, CuI, Et3N, rt, 5 h, 64%; (g) TsNHNH2, NaOAc, DME/H2O (5:3), reflux, 4 h, 85%.

5778
D. Fujita et al. / Tetrahedron Letters 46 (2005) 5775–5779
1987, 838–839; (c) Xie, Z.-F.; Nakamura, I.; Suemune, H.;
Sakai, K. J. Chem. Soc., Chem. Commun. 1988, 966–967.
significant difference was observed between the cis and
trans isomers. On the basis of structure–activity studies
of ordinary acetogenins possessing the hydroxylated
mono- or bis-THF ring(s), we previously concluded that
the stereochemistry of the hydroxylated THF ring por-
tion does not significantly affect the inhibitory
potency.18 It should however be realized that the stereo-
chemical difference in the bis-THF portion makes little
difference in the three-dimensional structure of this moi-
ety because of the flexibility, which was corroborated by
an exhaustive conformational space search analysis.18a
Using enantioselectively synthesized 1,2-cyclopentane-
diol bis-ether analogs in which the relative spatial posi-
tion of the two ether oxygen atoms is almost completely
fixed, the present study unambiguously supports the
previous conclusion. At the same time, it was also shown
that the spatial position of the two oxygen atoms slightly
affects the inhibitory potency (2 vs 5).
´
´
´
7. Bodai, V.; Orovecz, O.; Szakacs, G.; Novak, L.; Poppe, L.
Tetrahedron: Asymmetry 2003, 14, 2605–2612.
8. The data for 10a: 1H NMR (400 MHz, CDCl3): d 4.72,
4.69 (each d, J = 7.0 Hz, 2H), 4.00 (dt, J = 7.1, 7.1 Hz,
1H), 3.73 (dt, J = 7.1, 7.1 Hz, 1H), 3.43 (s, 3H), 3.41 (br s,
1H), 2.06–1.99 (m, 2H), 1.74–1.52 (m, 4H). ESI-MS (m/z)
169.2 [M+Na]+. Anal. Calcd for C7H14O3: C, 57.51; H,
9.65. Found: C, 57.31; H, 9.47. For 11a: 1H NMR
(500 MHz, CDCl3): d 4.73–4.70 (m, 2H), 4.08–4.07 (m,
1H), 3.95–3.91 (m, 1H), 3.41 (s, 3H), 2.56 (br s, 1H), 1.88–
1.69 (m, 5H), 1.55–1.51 (m, 1H). ESI-MS (m/z) 169.2
[M+Na]+. Anal. Calcd for C7H14O3: C, 57.51; H, 9.65.
1
Found: C, 57.33; H, 9.51. For 10b: H NMR (400 MHz,
CDCl3): d 4.73, 4.69 (each d, J = 8.0 Hz, 2H), 3.98 (dt,
J = 7.0, 7.0 Hz, 1H), 3.72 (dt, J = 7.0, 7.0 Hz, 1H), 3.43 (s,
3H), 3.33 (br s, 1H), 2.07–1.99 (m, 2H), 1.74–1.54 (m, 4H).
ESI-MS (m/z) 169.2 [M+Na]+. Anal. Calcd for C7H14O3:
1
C, 57.51; H, 9.65. Found: C, 57.42; H, 9.62. For 11b: H
NMR (500 MHz, CDCl3): d 4.73–4.70 (m, 2H), 4.09–4.06
(m, 1H), 3.94–3.92 (m, 1H), 3.41 (s, 3H), 2.54 (br s, 1H),
1.87–1.69 (m, 5H), 1.55–1.51 (m, 1H). ESI-MS (m/z) 169.2
[M+Na]+. Anal. Calcd for C7H14O3: C, 57.51; H, 9.65.
Found: C, 57.24; H, 9.49.
In conclusion, our work for the first time has demon-
strated that the hydroxylated bis-THF skeleton of natu-
ral acetogenins can be replaced with a much simpler
structure while maintaining very potent inhibitory activ-
ity at the enzyme level.
9. (a) Motoyama, T.; Yabunaka, H.; Miyoshi, H. Bioorg.
Med. Chem. Lett. 2002, 12, 2089–2092; (b) Yabunaka, H.;
Abe, M.; Kenmochi, A.; Hamada, T.; Nishioka, T.;
Miyoshi, H. Bioorg. Med. Chem. Lett. 2003, 13, 2385–
2388.
Acknowledgements
10. (a) Kuwabara, K.; Takada, M.; Iwata, J.; Tatsumoto, K.;
Sakamoto, K.; Iwamura, H.; Miyoshi, H. Eur. J. Biochem.
2000, 267, 2538–2546; (b) Takada, M.; Kuwabara, K.;
Nakato, H.; Tanaka, A.; Iwamura, H.; Miyoshi, H.
Biochim. Biophys. Acta 2000, 1460, 302–310.
This work was supported in part by a Grant-in-aid for
Scientific Research from the Japan Society for the Pro-
motion of Science (Grant 15380083 to H.M.).
11. (a) McClure, D. E.; Arison, B. H.; Baldwin, J. J. J. Am.
´
Chem. Soc. 1979, 101, 3666–3668; (b) Huerou, Y. L.;
Doyon, J.; Gree, R. L. J. Org. Chem. 1999, 64, 6782–6790.
References and notes
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12. Yamaguchi, M.; Hirao, I. Tetrahedron Lett. 1983, 24, 391–
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J.; Ley, S. V. Angew. Chem., Int. Ed. 2005, 44, 580–584. In
this article, a number of papers concerning the total
synthesis of natural acetogenins are listed in chronological
order.
3. (a) Yan, Z.-J.; Wu, H.-P.; Wu, Y.-L. J. Med. Chem. 2000,
43, 2484–2487; (b) Zeng, B.-B.; Wu, Y.; Yu, Q.; Wu,
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2002, 67, 3404–3408; (d) Zeng, B.-B.; Wu, Y.; Jiang, S.;
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X.-G.; Wu, Y.-L. Chem. Eur. J. 2003, 9, 282–290; (e)
Huang, G.-R.; Jiang, S.; Wu, Y.-L.; Jin, Y.; Yao, Z.-J.;
Wu, J.-R. ChemBioChem 2003, 4, 1216–1221; (f) Jiang, S.;
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15. Hart, D. J.; Hong, W.-P.; Hsu, L.-Y. J. Org. Chem. 1987,
52, 4665–4673.
24
16. The data for 2: colorless oil. ½aꢀ +20.7 (c 0.06, EtOH). 1H
NMR (400 MHz, CDCl3): dD6.99 (m, 1H), 5.00 (dq,
J = 1.5, 7.0 Hz, 1H), 3.80–3.74 (m, 4H), 3.47 (dd, J = 3.0,
9.6 Hz, 2H), 3.30 (dd, J = 9.5, 11.0 Hz, 2H), 2.43 (br s,
2H), 2.26 (t, J = 7.4 Hz, 2H), 1.98–1.86 (m, 2H), 1.59–1.53
(m, 4H), 1.45–1.26 (m, 40H), 1.41 (d, J = 7.0 Hz, 3H), 0.88
(t, J = 6.8 Hz, 3H). 13C NMR (100 MHz, CDCl3): d
174.02, 148.96, 134.41, 85.32, 73.72, 70.43, 33.21, 32.00,
29.79, 29.70, 29.69, 29.43, 29.41, 29.28, 27.48, 25.67, 25.26,
22.78, 20.90, 19.31, 14.22. ESI-MS (m/z) 617.5 [M+Na]+.
Anal. Calcd for C36H66O6: C, 72.68; H, 11.18. Found: C,
24
72.44; H, 10.96. For 3: colorless oil. ½aꢀD +28.5 (c 0.04,
EtOH). 1H NMR (400 MHz, CDCl3): d 6.99 (m, 1H), 5.00
(dq, J = 1.5, 7.0 Hz, 1H), 3.82–3.76 (m, 4H), 3.72 (br s,
1H), 3.64 (dd, J = 2.4, 9.3 Hz, 1H), 3.48 (dd, J = 3.0,
10.0 Hz, 1H), 3.45 (br s, 1H), 3.43 (dd, J = 6.8, 10.0 Hz,
1H), 3.20 (dd, J = 9.3, 9.3 Hz, 1H), 2.26 (t, J = 7.3 Hz,
2H), 1.85–1.70 (m, 6H), 1.61–1.25 (m, 40H), 1.41 (d,
J = 7.0 Hz, 3H), 0.88 (t, J = 6.8 Hz, 3H). 13C NMR
(100 MHz, CDCl3): d 173.94, 148.86, 134.35, 81.26,
80.41, 74.95, 73.72, 70.60, 69.93, 33.13, 32.80, 31.92,
29.71, 29.63, 29.58, 29.53, 29.35, 29.19, 28.55, 28.46, 27.40,
25.75, 25.54, 25.18, 22.70, 19.23, 19.17, 14.14. ESI-MS
4. It should be realized that cytotoxicity of potent natural
acetogenins like bullatacin is generally much more potent
than that of adriamycin (see Ref. 1).
´
5. Rodier, S.; Huerou, Y. L.; Renoux, B.; Doyon, J.; Renard,
P.; Pierre, A.; Gesson, J.-P.; Gree, R. Bioorg. Med. Chem.
´
´
Lett. 2000, 10, 1373–1375.
6. (a) Xie, Z.-F.; Suemune, H.; Nakamura, I.; Sakai, K.
Chem. Pharm. Bull. 1987, 35, 4454–4459; (b) Xie, Z.-F.;
Suemune, H.; Sakai, K. J. Chem. Soc., Chem. Commun.

D. Fujita et al. / Tetrahedron Letters 46 (2005) 5775–5779
5779
(m/z) 617.5 [M+Na]+. Anal. Calcd for C36H66O6: C, 72.68;
H, 11.18. Found: C, 72.47; H, 11.01. For 4: colorless oil.
1.90 (m, 2H), 1.59–1.53 (m, 4H), 1.45–1.26 (m, 40H), 1.41
(d, J = 7.0 Hz, 3H), 0.88 (t, J = 6.9 Hz, 3H). 13C NMR
(125 MHz, CDCl3): d 173.94, 148.87, 134.32, 85.60, 74.00,
70.64, 33.07, 31.91, 29.72, 29.68, 29.61, 29.45, 29.52, 29.34,
29.32, 29.19, 27.39, 25.55, 25.17, 22.69, 20.81, 19.22, 14.13.
ESI-MS (m/z) 617.5 [M+Na]+. Anal. Calcd for C36H66O6:
C, 72.68; H, 11.18. Found: C, 72.48; H, 10.94.
24
½aꢀD +16.6 (c 0.10, EtOH). 1H NMR (400 MHz, CDCl3): d
6.99 (m, 1H), 5.00 (dq, J = 1.5, 7.0 Hz, 1H), 3.82–3.76 (m,
4H), 3.72 (br s, 1H), 3.64 (dd, J = 2.4, 9.3 Hz, 1H), 3.48
(dd, J = 3.0, 10.0 Hz, 1H), 3.45 (br s, 1H), 3.43 (dd,
J = 6.7, 10.0 Hz, 1H), 3.20 (dd, J = 9.3, 9.3 Hz, 1H), 2.26
(t, J = 7.3 Hz, 2H), 1.85–1.70 (m, 6H), 1.61–1.25 (m, 40H),
1.41 (d, J = 7.0 Hz, 3H), 0.88 (t, J = 6.8 Hz, 3H). 13C
NMR (100 MHz, CDCl3): d 173.93, 148.86, 134.35, 81.26,
80.41, 74.96, 73.71, 70.60, 69.93, 33.13, 32.80, 31.92, 29.70,
29.62, 29.60, 29.58, 29.52, 29.35, 29.19, 28.58, 28.46, 27.40,
25.74, 25.55, 25.18, 22.70, 19.23, 19.17, 14.14. ESI-MS (m/
z) 617.5 [M+Na]+. Anal. Calcd for C36H66O6: C,72.68; H,
11.18. Found: C, 72.39; H, 11.03. For 5: colorless oil.
17. Ichimaru, N.; Murai, M.; Abe, M.; Hamada, T.; Yamada,
Y.; Makino, S.; Nishioka, T.; Makabe, H.; Makino, A.;
Kobayashi, T.; Miyoshi, H. Biochemistry 2005, 44, 816–
825.
18. (a) Miyoshi, H.; Ohshima, M.; Shimada, H.; Akagi, T.;
Iwamura, H.; McLaughlin, J. L. Biochim. Biophys. Acta
1998, 1365, 443–452; (b) Makabe, H.; Miyawaki, A.;
Takahashi, R.; Hattori, Y.; Konno, H.; Abe, M.; Miyoshi,
H. Tetrahedron Lett. 2004, 45, 973–977; (c) Makabe, H.;
Hattori, Y.; Kimura, Y.; Konno, H.; Abe, M.; Miyoshi,
H.; Tanaka, A.; Oritani, T. Tetrahedron 2004, 60, 10651–
10657.
24
½aꢀD +69.4 (c 0.04, EtOH). 1H NMR (500 MHz, CDCl3): d
6.99 (m, 1H), 5.00 (dq, J = 1.5, 7.0 Hz, 1H), 3.80–3.73 (m,
4H), 3.52 (dd, J = 2.9, 9.6 Hz, 2H), 3.26 (dd, J = 8.3,
8.3 Hz, 2H), 2.52 (br s, 2H), 2.25 (t, J = 7.4 Hz, 2H), 1.95–