Novel acyl α-pyronoids, dictyopyrone A, B, and C, from Dictyostelium cellular slime molds

Article abstract of DOI:10.1021/jo991338i

For the elucidation of the diversity of secondary metabolites of Dictyostelium cellular slime molds, we investigate the constituent of three species of slime molds. From the methanol extract of their fruit bodies, we obtained three novel compounds, dictyopyrone A (1) and B (2) from D. discoideum and D. rhizoposium and dictyopyrone C (3) from D. longosporum. They possess a unique α-pyrone moiety with a side chain at the C-3 position. Their relative structures were elucidated by spectral means, and the absolute configuration was confirmed by asymmetric synthesis of 1. Since these compounds were obtained from different species of Dictyostelium slime molds, they may be a type of compound common to this genus.

Full text of DOI:10.1021/jo991338i

J . Org. Chem. 2000, 65, 985-989
985
Novel Acyl r-P yr on oid s, Dictyop yr on e A, B, a n d C, fr om
Dictyosteliu m Cellu la r Slim e Mold s
Yoshiaki Takaya,† Haruhisa Kikuchi,† Yuichi Terui,† J un Komiya,† Ken-Ichi Furukawa,‡
Kazuhiko Seya,‡ Shigeru Motomura,‡ Akira Ito,§ and Yoshiteru Oshima*,†
Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-yama, Sendai 980-8578,
Hirosaki University School of Medicine, Zaifu-cho, Hirosaki 036-8562, and Kyorin Pharmaceutical Co.,
Ltd., 2-5 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, J apan
Received August 24, 1999
For the elucidation of the diversity of secondary metabolites of Dictyostelium cellular slime molds,
we investigate the constituent of three species of slime molds. From the methanol extract of their
fruit bodies, we obtained three novel compounds, dictyopyrone A (1) and B (2) from D. discoideum
and D. rhizoposium and dictyopyrone C (3) from D. longosporum. They possess a unique R-pyrone
moiety with a side chain at the C-3 position. Their relative structures were elucidated by spectral
means, and the absolute configuration was confirmed by asymmetric synthesis of 1. Since these
compounds were obtained from different species of Dictyostelium slime molds, they may be a type
of compound common to this genus.
In tr od u ction
slime molds exhaustively to classify the compounds
produced by the microorganism. In this paper, the
structure elucidation and an asymmetric total synthesis
of three novel R-pyrone compounds, dictyopyrone A (1),
B (2), and C (3), and the potency of inhibition against
smooth muscle contraction of 1 are described.
The cellular slime molds, Myxomycota, which is known
as the most primitive fungus, have long been established
as an excellent model organism for the study of various
aspects of multicellular development, because of their
short and very simple life cycle. The amoebas, germinated
from spores, feed on bacteria by phagocytosis, and
starving makes them aggregate to form a mount. The
mount differentiates into either stoke cells or spores.
Several chemical stimuli, such as DIF-1 (4),1 discad-
enine,2 and cAMP,3 are identified as physiologically active
substances which act during their life cycle, but few other
secondary metabolites have been reported. Many bioac-
tive compounds have been obtained from various kinds
of microorganisms; however, the frequency of encounter-
ing novel skeletal compounds is decreasing. On the other
hand, the chemistry of the slime molds is one of terrae
incognitae. Among the compounds isolated from cellular
slime molds, DIF-1 (4), a differentiation-inducing factor
of Dictyostelium slime molds, shows a unique structure
bearing a hexasubstituted benzene ring with two chlorine
atoms, and other compounds such as discadenine2 or
dictyosterol4 are also structurally characteristic. From
these facts, it is believed that slime molds have the ability
to produce novel metabolites. Accordingly, we set about
exploring the diversity of the secondary metabolites of
cellular slime molds and their utility as a resource to
develop drugs of the future. In the first step of this
project, we decided to examine the constituent of the
Resu lts a n d Discu ssion
Isola tion a n d Str u ctu r e Elu cid a tion . Ethyl acetate-
soluble oil (1.2 g), obtained from methanol extracts (5.6
g) of the cultured fruit body of D. discoideum (wet 109
g), was fractionated over silica gel. The fraction eluted
with n-hexane-ethyl acetate (4:1) afforded 1 (2.1 mg) and
2 (0.4 mg). In the same manner, 1 (3.3 mg) and 2 (2.7
mg) were obtained from D. rhizoposium, and 3 (0.5 mg)
was obtained from D. longosporum.
The molecular formula C19H30O3 indicated for 1, [R]25
D
+33.8 (c 0.071, CHCl3), a colorless needle, was estab-
lished by a molecular ion peak at m/ z 306.2260 [M]+ in
* To whom correspondence should be addressed. Phone:
+81-22-217-6822. Fax:
mail.pharm.tohoku.ac.jp.
† Tohoku University.
+81-22-217-6821. E-mail:
oshima@
1
its HREI-MS and analyses of its H and 13C NMR spectra
(Table 1). The 13C NMR spectrum displayed the presence
of a keto carbonyl, an ester carbonyl, four olefinic, an
oxymethine, nine methylene, and three methyl carbons.
1H-1H COSY and HMBC experiments showed three
partial structures, I, II, and III (Figure 1). The tetra-
substituted olefin of unit I was established by long-range
correlation peaks from C-3 and C-4 to both H-5 and H-7,
and from the methyl carbon (C-7) to H-5 in the HMBC
‡ Hirosaki University.
§ Kyorin Pharmaceutical Co., Ltd.
(1) Morris, H. R.; Taylor, G. W.; Masento, M. S.; J ermyn, K. A.; Kay,
R. R. Nature 1987, 328, 811-814.
(2) Abe, H.; Uchiyama, M.; Tanaka, Y.; Saito, H. Tetrahedron Lett.
1976, 42, 3801-3810.
(3) Konijn, T. M.; van de Meene, J . G. C.; Bonner, J . T.; Barkley, D.
S. Biochemistry 1967, 58, 1152-1154.
(4) Nes, W. D.; Norton, R. A.; Crumley, F. G.; Madigan, S. J .; Katz,
E. R. Proc. Natl. Acad. Sci. U.S.A. 1990, 87, 7565-7569.
10.1021/jo991338i CCC: $19.00 © 2000 American Chemical Society
Published on Web 01/27/2000

986 J . Org. Chem., Vol. 65, No. 4, 2000
Takaya et al.
Ta ble 1. NMR Da ta of 1, 2, a n d 3a
2
1
3
position
1Hb
13Cc
1Hb
1Hd
2
3
4
5
163.4 (s)
130.3 (s)
156.4 (s)
38.0 (t)
2.45 (1H, dd, 18.5, 11.6)
2.31 (1H, dd, 18.5, 3.7)
4.55 (1H, ddq, 11.6, 3.7, 6.1)
2.01 (3H, s)
2.44 (1H, dd, 18.3, 11.6)
2.30 (1H, dd, 18.3, 3.7)
4.54 (1H, ddq, 11.6, 3.7, 6.1)
2.01 (3H, s)
2.43 (1H, dd, 18.1, 10.7)
2.23 (1H, dd, 18.1, 4.1)
4.53 (1H, ddq, 10.7, 6.3, 4.1)
2.00 (3H, d, 0.8)
6
7
8
1′
2′
3′
4′-8′
73.3 (d)
21.1 (q)
20.7 (q)
203.7 (s)
43.7 (t)
24.0 (t)
29.4 (t)
29.4 (t)
29.6 (t)
29.6 (t)
29.8 (t)
32.8 (t)
131.9 (d)
124.8 (d)
18.2 (q)
1.44 (3H, d, 6.1)
1.44 (3H, d, 6.1)
1.42 (3H, d, 6.3)
2.73 (2H, td, 7.3, 2.4)
1.61 (2H, m)
1.2-1.4 (10H, m)
2.73 (2H, td, 7.3, 2.4)
1.61 (2H, m)
1.2-1.4 (14H, m)
2.71 (2H, td, J ) 7.7, 1.4)
1.5-1.7 (2H, m)
1.2-1.4 (16H, m, H-4′-11′)
9′
10′
11′
12′
14′
1.94 (2H, m)
5.39-5.42 (2H, m, H-10′-11′)
1.95 (2H, m)
5.39-5.42 (2H, m, H-12′-13′)
1.64 (3H, dd, 3.7, 1.2)
1.64 (3H, dt, 3.7, 1.4)
0.86 (3H, t, 7.1)
a
b
The number of protons, splitting patterns, and coupling constants (Hz) of 1H NMR are indicated in parentheses. Measured at 500
MHz. c Measured at 125 MHz. Measured at 300 MHz.
d
peared in the case of 3, and a triplet methyl signal (δH
0.86) was observed instead. As a result, the structure of
compound 3 with a saturated side chain was suggested.
Syn th esis a n d Absolu te Con figu r a tion . The wave-
length and intensity of the Cotton effect in the CD spectra
of 1, 2, and 3 are almost the same, suggesting that they
have the same absolute stereochemistry at C-6. The
structures of these compounds, including the absolute
F igu r e 1. Partial structures of dictyopyrone A (1).
spectrum. However, it was observed that there remained
an ester group and four methylene carbons which were
not included in these partial structures. The ester group
was attached to C-6 of unit I, since C-6 was assumed to
be an oxymethine carbon as judged from the chemical
shift of the 13C NMR signal (δC 73.3). Moreover, all
signals of the four methylene chains in the NMR spectra
were observed obviously in the aliphatic region, δH 1.2-
1.4 and δC 29.4-29.8, indicating that the methylene chain
must be connected between the methylene of unit II and
unit III. On the basis of consideration of these partial
structures mentioned above and the molecular formula,
the unique planar structure of compound 1, bearing an
R-pyrone moiety, was given. The base ion (m/ z 153),
which was formed by the bond cleavage between C-1′ and
C-2′, also agreed with the proposed structure. The E
configuration was assigned to the C-10′-C-11′ double
bond by comparison of the chemical shifts of C-9′ (δC 32.8)
and C-12′ (δC 18.2) with the calculated values (δC (E) 33.0,
(Z) 27.0 for C-9′; δC (E) 17.0, (Z) 11.0 for C-12′).
configuration, were established by an asymmetric total
synthesis of compound 1 and its stereoisomer using
commercially available (2R,4R)- or (2S,4S)-2,4-pen-
tanediol (5) as a chiral source. Our synthetic strategy is
to couple a â-keto acid moiety, corresponding to C-2-
C-3 and a side chain, with the 2,4-pentanediol (C-4-C-
8).
Tridecanedioic acid monopotassium salt prepared from
tridecanedioic acid (6) with an equimolar amount of
potassium hydroxide was transformed to its monobenzyl
ester (7) in 68% yield (Scheme 1).5 The monoester 7 was
converted into terminal olefinic ester 8 by oxidative
decarboxylation using lead tetraacetate and a catalytic
amount of cupric acetate.6 The terminal double bond was
isomerized predominantly to the desired E configuration
at the ∆10′ position with CoCl2/Ph3P/NaBH4 at -18 °C
for 6 h in 84% (Z: 7%).7 Hydrolysis of the benzyl ester
gave (E)-10-dodecenoic acid (10), which corresponds to
the side chain moiety of dictyopyrone A (1).
Elongation of a two-carbon unit (C-2-C-3) to the acid
10 was achieved by treatment of thionyl chloride followed
by the malonic ester synthesis using Meldrum’s acid.8
Transesterification and decarboxylation of acylated Mel-
drum’s acid (11) occurred in succession with (2S,4S)-2,4-
pentanediol (5S) in benzene by refluxing, and a â-ke-
toester (12) was obtained. Oxidation of the secondary
alcohol using PDC and subsequent intramolecular aldol
The HREI-MS of 2, [R]25 +36.6 (c 0.160, CHCl3), a
D
colorless needle, gave a molecular formula, C21H34O3,
which differs from that of 1 by two methylene units. The
1H and 13C NMR spectra of 2 were almost the same as
those of 1, except the appearance of signals assigned to
additional methylene moieties. These findings revealed
that 2 had an elongated side chain by two methylenes
compared with 1.
Dictyopyrone C (3), a colorless amorphous solid, [R]25
D
(5) Remaud, G.; Balgobin, N.; Glemarec, C.; Chattopadhyaya, J .
Tetrahedron 1989, 45, 1537-1548.
+71.0 (c 0.031, CHCl3), showed a molecular ion peak at
m/ z 308 in its EI-MS, which differs from that of 1 by 2
(6) Bacha, J . D. and Kochi, J . K. Tetrahedron 1968, 24, 2215-2226.
(7) Satyanarayana, N. and Periasamy, M. J . Organomet. Chem.
1987, 319, 113-117.
1
mass units. The H NMR spectra of 1 and 3 were very
similar, but the signals of two olefinic protons (δH 5.39-
5.42) and an allyl methyl proton (δH 1.64) of 1 disap-
(8) Oikawa, Y.; Sugano, K.; Yonemitsu, O. J . Org. Chem. 1978, 43,
2087-2088.

Novel Acyl R-Pyronoids from Dictyostelium Slime Molds
J . Org. Chem., Vol. 65, No. 4, 2000 987
Sch em e 1a
and chiral total synthesis. Though some R-pyronoids with
a hydroxyl group at the C-4 position are known,9 dicty-
opyrones bear a unique 3-acyl-4,6-dialkyl-R-pyrone ring,
which has not hitherto been reported, to the best of our
knowledge. Moreover, in this study, 1 and 2 were
obtained from two species, D. discoideum and D. rhizo-
posium, and 3 was obtained from D. longosporum, as the
comparatively major secondary metabolites except dic-
tyosterol. These facts suggest that the compounds have
an important role in the life cycle of cellular slime molds.
It is interesting that compounds 1 and 14 possessing
varying lengths of the side chain differ in inhibitory
activity against smooth muscle contraction. Further
investigations on the structure-activity relationships are
now in progress using compounds synthesized by the
methods shown in Scheme 1.
a
Exp er im en ta l Section
Reagents and conditions (corrected yields): (i) KOH, methanol;
(ii) PhCH2Br, n-Bu4NBr, toluene, reflux, 6 h (68% from 6); (iii)
Pb(OAc)4, Cu(OAc)2, pyridine, benzene, reflux, 4 h (76%); (iv) Ph3P,
CoCl2, NaBH4, THF, -18 °C (91%); (v) NaOH, CH3CN-H2O (99%);
(vi) SOCl2, benzene, reflux, 2 h; (vii) Meldrum’s acid, DMAP,
CH2Cl2, 0 °C f rt; (viii) 5S or 5R, benzene, reflux (65% from 10);
(ix) PDC, DMF (90%); (x) K2CO3, CH3CN, 50 °C (67% from 12).
Gen er a l Meth od s. Melting points were uncorrected. Ana-
lytical TLC was performed on silica gel 60 F254 (Merck).
Column chromatography was carried out on silica gel 60 (70-
230 mesh, Merck). All NMR spectra were recorded in CDCl3.
Chemical shifts for 1H and 13C NMR are given in parts per
million (δ) relative to tetramethylsilane (δH 0.00) and CDCl3
(δC 77.1) as internal standards, respectively.
condensation allowed us to complete the synthesis of (S)-
dictyopyrone A (1S). In the same manner, (R)-dictyo-
pyrone A (1R) was produced by using (2R,4R)-2,4-
pentanediol (5R). Specific rotation of the synthetic (S)-
dictyopyrone (1S) was identical with that of the natural
compound (1). From this result, the absolute configura-
tion of compound 1 was determined as S, and conse-
quently, compounds 2 and 3 were clarified to be of S
configuration.
Biologica l Eva lu a tion . Though very small amounts
of compounds 1-3 were isolated in this study to submit
to a bioassay, we investigated, as one of the pharmaco-
logical evaluations, the potency of inhibition against
smooth muscle contraction of synthesized 1 and a model
compound (14) of the transformation from 9 into 1 in the
Or ga n ism a n d Cu ltu r e Con d ition s. The cellular slime
molds used in this study were (i) D. discoideum (NC-4), D.
longosporum (C-193), and D. rhizoposium (C-224). D. discoi-
deum and the other two species were kindly supplied by
Professor Y. Maeda, Tohoku University, and Dr. H. Hagiwara,
National Science Museum, Ibaraki, J apan, respectively. Spores
of theses species were cultured at 22 °C with E. coli Br on
A-medium consisting of 0.5% glucose, 0.5% polypeptone, 0.05%
yeast extract, 0.225% KH2PO4, 0.137% Na2HPO4‚12H2O, 0.05%
MgSO4‚7H2O, and 1.5% agar. When the fruit body had been
formed in several days, they were harvested for extraction.
Mea su r em en t of Isom etr ic Con tr a ction . The thoracic
aorta was prepared from male wister rats. The endothelium
was removed by gently rubbing the endothelial surface with
cotton pellets. The deendothelialization was checked by the
abolition of acetylcholine-induced relaxation. The aorta was
cut into helical strips approximately 1.5-2 mm in width and
20 mm in length. One end of the strip was secured to the glass
tissue holder by a silk ligature, and the other end was
connected to a force-displacement transducer. The strip was
suspended in a 20 mL organ bath containing HEPES-buffered
Krebs solution of the following composition (mM): NaCl (120),
KCl, (4.8), MgSO4, (1.3), glucose, (5.8), CaCl2, (1.2), KH2PO4,
(1.2), NaHCO3, (12.6), HEPES, (10). The solution was gassed
with 95% O2-5% CO2. The tissues were equilibrated for 1 h
under a resting tension of 1 g. Isometric contraction was then
measured by the transducer. The strip was precontracted three
times by adding KCl (final concentration 60 mM).
Isola tion of Dictyop yr on e A (1) a n d B (2). The cultured
fruit body (wet 109 g) of D. discoideum was extracted twice
with methanol at room temperature to give the extract (5.6
g). The methanol extract (5.6 g) was partitioned with ethyl
acetate and water to yield ethyl acetate solubles (1.1 g). The
ethyl acetate solubles were chromatographed over SiO2, and
the column was eluted with n-hexane-ethyl acetate mixtures
with increasing polarity. n-Hexane-ethyl acetate (4:1) eluent
was further chromatographed over SiO2 using an n-hexane-
diethyl ether mixture, followed by SiO2 column chromatogra-
phy using n-hexane-chloroform to give crude dictyopyrones.
The crude sample was purified with ODS column, and then 1
(2.1 mg) and 2 (0.4 mg) were obtained. In the same manner,
the cultured fruit body (wet 202 g) of D. rhizoposium gave 1
(3.3 mg) and 2 (2.7 mg). A colorless needle crystal was
synthetic scheme. As a result, compound 14 inhibited the
contraction of rat aorta evoked by 30 mM KCl, 10-6
M
phenylephrine, and 10-6 M serotonin with IC50 values of
0.35, 1.4, and 0.14 µM, respectively, whereas 1 was
inactive. The inhibitory activities of 14 were not so strong
compared to those of verapamil (IC50 for KCl-induced
contraction, 0.1 µM), prazosin (IC50 for phenylephrine-
induced contraction, 1.4 nM), and methysergide (IC50 for
serotonin-induced contraction, 0.1 µM), but from the
results mentioned above, it is deduced that inhibitory
activity may be affected by the chain length of these
compounds, and structure-activity relationship studies
are hoped to give more effective compounds.
Con clu sion
Three novel R-pyronoids, dictyopyrones A (1), B (2), and
C (3), were isolated from the fruit body of Dictyostelium
silme molds, and their structures, including the absolute
configuration, were elucidated by spectroscopic analysis
(9) Tabuchi, H. and Ichihara, A. J . Chem. Soc., Perkin Trans. 1 1994,
125-133 and references cited therein.

988 J . Org. Chem., Vol. 65, No. 4, 2000
Takaya et al.
generated in a very concentrated solution of 1 or 2 in an
bined, evaporated, suspended with methanol (15 mL), and
extracted with n-hexane twice. The n-hexane layer was
combined and evaporated. The residue was separated by SiO2
column chromatography (n-hexane:benzene ) 3:1) to give a
mixture of 9 and benzyl (Z)-10-dodecenoate (232 mg, 0.806
mmol, 91%). HPLC analysis showed that the ratio of E-isomer
to Z-isomer was 12:1. The E/ Z mixture was used as 9 without
further purification throughout the following synthetic scheme.
Data for 9: a colorless oil; 1H NMR (300 MHz) δ 7.3-7.4 (5H,
m), 5.39-5.42 (2H, m), 5.11 (2H, s), 2.35 (2H, t, J ) 7.6 Hz),
1.9-2.0 (2H, m), 1.65 (2H, dt, J ) 4.7, 1.4 Hz), 1.6-1.7 (2H,
m), 1.2-1.4 (10H, m); 13C NMR (75 MHz) δ 173.9, 136.3, 131.8,
128.7 (2C), 128.3 (3C), 124.7, 66.1, 34.3, 32.6, 29.6, 29.5, 29.3,
29.2, 29.1, 24.9, 17.9; EI-MS m/ z 288 [M]+, 197, 179, 161, 137,
91 (base); HREI-MS m/ z 288.2079 (288.2088 calcd for C19H28O2).
(E)-10-Dod ecen oic Acid (10). 9 (841 mg, 2.92 mmol) was
dissolved in acetonitrile (50 mL), and 1 M sodium hydroxide
(10 mL) was added to this solution. The reaction was carried
out at 60 °C for 24 h. The mixture was poured into 1 M
hydrochloric acid (30 mL) and extracted with diethyl ether
three times. The organic layer was extracted with 1 M sodium
hydroxide three times to remove benzyl alcohol. The aqueous
layer was collected, acidified with 1 M hydrochloric acid again,
and extracted with diethyl ether three times. The organic layer
was washed with water and brine, dried over anhydrous
sodium sulfate, and evaporated. The residue was purified by
SiO2 column chromatography (n-hexane:EtOAc ) 4:1) to give
10 (contained Z-isomer) (571 mg, 99%). Data for 10: a colorless
oil; 1H NMR (300 MHz) δ 11.5-11.6 (1H, br.s), 5.39-5.42 (2H,
m), 2.32 (2H, t, J ) 7.5 Hz), 1.9-2.0 (2H, m), 1.65 (2H, dt, J
) 4.7, 1.4 Hz), 1.6-1.7 (2H, m), 1.2-1.4 (10H, m); 13C NMR
(75 MHz) δ 180.8, 131.7, 124.7, 34.1, 32.5, 29.6, 29.5, 29.3, 29.2,
29.1, 24.6, 17.8; EI-MS m/ z 198 [M]+, 180, 138, 55 (base);
HREI-MS m/ z 198.1593 (198.1620 calcd for C12H22O2).
(1S,3S)-3-Hyd r oxy-1-m eth ylbu tyl (E)-3-Oxotetr a d ec-
12-en oa te (12). Thionyl chloride (0.5 mL) and N,N-dimeth-
ylformamide (50 mg) were added to a solution of 10 (268 mg,
1.35 mmol) in benzene (2 mL). After the mixture was refluxed
for 2 h, the solvent was evaporated. The residue was dissolved
in dichloromethane (2 mL) at 0 °C. Meldrum’s acid (214 mg,
1.49 mmol; Nacalai Tesque, Kyoto) and 4-(dimethylamino)-
pyridine (330 mg, 2.70 mmol) in dichloromethane (2 mL) were
added to this solution. After being stirred for 1.5 h at 0 °C
and 1 h at room temperature, the mixture was evaporated and
dissolved in diethyl ether. This solution was poured into 1 M
hydrochloric acid and extracted with diethyl ether three times.
The organic layer was combined, washed with water and brine,
dried over anhydrous sodium sulfate, and evaporated. The
residue was mainly composed of 5-[(E)-10-dodecenoyl]-2,2-
dimethyl-1,3-dioxane-4,6-dione (11), but purification was not
carried out because of its unstableness. (2S,4S)-2,4-Pen-
tanediol (422 mg, 4.06 mmol; Wako Pure Chemicals, Osaka)
and 11 in benzene were refluxed for 3 h, cooled to room
temperature, and evaporated. The residue in diethyl ether was
washed with 0.5 M sodium hydroxide, water, and brine, dried
over anhydrous sodium sulfate, and evaporated. The residue
was separated by SiO2 column chromatography (n-hexane:
ethyl acetate ) 4:1) to give 12 (contained Z-isomer) (287 mg,
65%). Data for 12: a colorless oil; 1H NMR (300 MHz) δ 5.39-
5.42 (2H, m), 5.21 (1H, tq, J ) 3.3, 6.3 Hz), 3.75-3.9 (1H, m),
3.46 (2H, s), 2.85-2.9 (1H, br s), 2.52 (2H, t, J ) 7.4 Hz), 1.9-
2.0 (2H, m), 1.5-1.7 (6H, m), 1.2-1.4 (10H, m), 1.28 (3H, d, J
) 6.3 Hz), 1.19 (3H, d, J ) 6.0 Hz); 13C NMR (75 MHz) δ 203.5,
167.9, 131.6, 124.7, 69.6, 63.4, 49.4, 45.6, 43.1, 32.5, 29.4, 29.2,
29.1, 29.0, 28.9, 23.3, 23.1, 20.5, 17.8; EI-MS m/ z 327 [M]+,
309, 241, 222, 69, 55, 45 (base); HREI-MS m/ z 327.2515
(327.2533 calcd for C19H35O4).
n-hexane-ethyl acetate mixture. Data for 1: [R]25 +33.8 (c
D
0.071, CHCl3); a colorless needle; mp 31-32 °C; UV λmax
(hexane) (nm (log ꢀ)) 216 (sh, 3.72); CD λ (dioxane) (nm (∆ꢀ))
269.6 (1.67), 234.0 (3.92); IR νmax (CHCl3) 1707 cm-1; 1H NMR
(500 MHz) and 13C NMR (125 MHz) data are shown in Table
1; HREI-MS m/ z 306.2200 [M]+ (306.2193 calcd for C19H30O3).
Data for 2: [R]25 +36.6 (c 0.160, CHCl3); a colorless needle;
D
UV λmax (hexane) (nm (log ꢀ)) 215 (sh, 3.84); CD λ (dioxane)
(nm (∆ꢀ)) 261.6 (sh, 1.80), 236.2 (3.75), 207.8 (-0.58); 1H NMR
(500 MHz) data are shown in Table 1; HREI-MS m/ z 334.2467
[M]+ (334.2508 calcd for C21H34O3).
Isola tion of Dictyop yr on e C (3). 3 (0.5 mg) was obtained
in the same manner described in the case of 1 from the
methanol extract of the cultured fruit body of D. longosporum
(wet 11 g). Data for 3: [R]25 +71.0 (c 0.031, CHCl3); an
D
amorphous solid; UV λmax (hexane) (nm (log ꢀ)) 214 (sh, 3.80);
CD λ (dioxane) (nm (∆ꢀ)) 261.4 (sh, 2.26), 238.2 (4.67), 207.6
1
(-1.15); H NMR (300 MHz) data are shown in Table 1; EI-
MS m/ z 308 [M]+.
Ben zyl Hyd r ogen Tr id eca n ed ioa te (7). Potassium hy-
droxide solution (10%) in methanol (11.0 mL, 19.7 mmol) was
added dropwise to a stirred solution of tridecanedioic acid (6)
(4.8 g, 19.7 mmol, Wako Pure Chemicals, Osaka) in methanol
(150 mL) at room temperature, and then a colorless salt
precipitated. After being stirred for 20 min, the mixture was
evaporated to give the monopotassium salt of tridecanedioic
acid. This salt was suspended in dry toluene (50 mL), and the
reaction mixture was mixed with tetra-n-butylammonium
bromide (546 mg, 1.97 mmol) and benzyl bromide (2.57 mL,
21.6 mmol). The mixture was refluxed for 6 h. After being
cooled to room temperature, the mixture was poured into 0.5
M hydrochloric acid (100 mL) and extracted with diethyl ether
three times. The organic layer was washed with water and
brine, dried over anhydrous sodium sulfate, and evaporated.
The residue was purified by SiO2 column chromatography (n-
hexane:EtOAc ) 19:1, 4:1, and 2:1) to give dibenzyl ester (1.83
g, 22%), monobenzyl ester (7) (3.42 g, 52%), and recovered
tridecanedioic acid (1.15 g, 24%). Data for 7: a colorless needle;
1H NMR (300 MHz) δ 7.3-7.4 (5H, m), 5.12 (2H, s), 2.35 (2H,
t, J ) 7.4 Hz), 2.34 (2H, t, J ) 7.4 Hz), 1.55-1.70 (4H, m),
1.2-1.4 (14H, m); 13C NMR (75 MHz) δ 180.3, 174.0, 136.3,
128.7 (2C), 128.3 (3C), 66.1, 34.3, 34.0, 29.4, 29.3 (2C), 29.2
(2C), 29.0, 29.0, 24.9, 24.6; EI-MS m/ z 334 [M]+, 316, 306, 288,
227, 107, 91; HREI-MS m/ z 334.2133 (334.2144 calcd for
C
20H30O4).
Ben zyl 11-Dod ecen oa te (8). Monobenzyl tridecanedioate
(7) (5.64 g, 16.9 mmol), lead(IV) tetraacetate (15.0 g, 33.8
mmol), copper(II) acetate monohydrate (674 mg, 3.38 mmol),
and pyridine (682 mL, 8.44 mmol) were dissolved in benzene
(60 mL), stirred for 30 min at room temperature, and refluxed
for 4 h. After cooling, the mixture was filtrated through Celite
with diethyl ether. The filtrate was washed with 0.5 M
hydrochloric acid, water, and brine, dried over anhydrous
sodium sulfate, and evaporated. The residue was separated
by SiO2 column chromatography (n-hexane:EtOAc ) 19:1 and
4:1) to give 8 (2.13 g, 44%) and recovered 7 (2.35 g, 42%). Data
1
for 8: a colorless oil; H NMR (300 MHz) δ 7.3-7.4 (5H, m),
5.80 (1H, ddt, J ) 17.0, 10.2, 6.7 Hz), 5.11 (2H, s), 4.99 (1H,
ddt, J ) 17.0, 2.2, 1.1 Hz), 4.92 (1H, ddt, J ) 10.2, 2.2, 1.1
Hz), 2.35 (2H, t, J ) 7.5 Hz), 2.03 (2H, q, J ) 7.2 Hz), 1.64
(2H, quint, J ) 7.5 Hz), 1.2-1.4 (12H, m); 13C NMR (75 MHz)
δ 173.9, 139.4, 136.3, 128.7 (2C), 128.3 (3C), 114.3, 66.1, 34.3,
33.8, 29.4 (2C), 29.2, 29.1 (2C), 28.9, 24.9; EI-MS m/ z 288 [M]+,
197, 182, 108, 91 (base); HREI-MS m/ z 288.2087 (288.2088
calcd for C19H28O2).
Ben zyl (E)-10-Dod ecen oa te (9). Cobalt(II) chloride (230
mg, 1.77 mmol) and triphenylphosphine (1.39 g, 5.30 mmol)
were dissolved in dry THF (12 mL) under argon at -18 °C.
After being stirred for 15 min, this suspension was treated
with sodium borohydride (66.9 mg, 1.77 mmol) and stirred for
30 min. Solution of 8 (255 mg, 0.88 mmol) in dry THF (6 mL)
was added, and the mixture was kept for 24 h. The mixture
was poured into 1 M hydrochloric acid (10 mL) and extracted
with diethyl ether three times. The organic layer was com-
(S)-3-Oxo-1-m eth ylbu tyl (E)-3-Oxotetr a d ec-12-en oa te
(13). 12 (261 mg, 0.80 mmol) in DMF (5 mL) was treated with
PDC (904 mg, 2.40 mmol) at room temperature for 12 h. The
mixture was filtrated through Celite with diethyl ether. The
filtrate was washed with 0.5 M hydrochloric acid, water, and
brine, dried over anhydrous sodium sulfate, and evaporated.
The residue was separated by SiO2 column chromatography
(n-hexane:ethyl acetate ) 4:1) to give 13 (contained Z-isomer)

Novel Acyl R-Pyronoids from Dictyostelium Slime Molds
J . Org. Chem., Vol. 65, No. 4, 2000 989
(234 mg, 90%). Data for 13: a colorless oil; 1H NMR (300 MHz)
δ 5.35-5.45 (4H, m), 3.39 (2H, s), 2.84 (1H, dd, J ) 16.8, 6.9
Hz), 2.59 (1H, dd, J ) 16.8, 6.8 Hz), 2.51 (2H, t, J ) 7.4 Hz),
2.16 (3H, s), 1.9-2.0 (2H, m), 1.64 (3H, dd, J ) 3.2, 1.2 Hz),
1.55-1.65 (2H, m), 1.30 (3H, d, J ) 8.3 Hz), 1.2-1.4 (10H,
m); 13C NMR (75 MHz) δ 205.4, 203.2, 166.7, 131.7, 124.7, 68.0,
49.3, 49.1, 42.9, 32.5, 30.3, 29.5, 29.2, 29.1, 29.0, 28.9, 23.3,
19.7, 17.8; EI-MS m/ z 325 [M + H]+, 222, 85, 43 (base); HREI-
MS m/ z 325.2406 (325.2377 calcd for C19H33O4).
water-acetonitrile (4:6-0:10). Data for synthetic 1: [R]25
D
+33.9 (c 1.234, CHCl3); other spectral data were identical with
those of the natural product. Data for the Z-isomer of 1: 1H
NMR (300 MHz) δ 5.35-5.47 (2H, m), 4.55 (1H, ddq, J ) 3.8,
6.3, 11.7 Hz), 2.74 (2H, dt, J ) 1.4, 7.4 Hz), 2.45 (1H, dd, J )
18.1, 11.7 Hz), 2.33 (1H, dd, J ) 18.1, 3.8 Hz), 2.01 (3H, s),
1.95-2.10 (2H, m), 1.60 (3H, d, J ) 5.5 Hz), 1.55-1.65 (2H,
m), 1.44 (3H, d, J ) 6.3 Hz), 1.2-1.4 (10H, m).
(S)-3-[(E)-Dod ec-12-en oyl]-5,6-d ih yd r o-4,6-d im et h yl-
2H-p yr a n -2-on e (Dictyop yr on e A) (1). An acetonitrile solu-
tion (4 mL) of 13 (47.3 mg, 0.15 mmol) was treated with
potassium carbonate (300 mg) at 55 °C for 24 h. The reaction
mixture was filtered, and the filtrate was poured into 1 M
hydrochloric acid (15 mL) and extracted with diethyl ether
three times. The organic layer was combined, washed with
water and brine, dried over anhydrous sodium sulfate, and
evaporated. The residue was separated by SiO2 column chro-
matography (n-hexane:ethyl acetate ) 4:1) to give 1 (contained
Z-isomer) (17 mg, 37%) and 13 (21 mg, 45%). 1 and its Z-isomer
were separated by preparative HPLC using TSKgel ODS 120A
(25 i.d. × 250 mm, TOSOH, Tokyo) by a linear gradient of
Ack n ow led gm en t. This work was supported in part
by a Grant-in-Aid for Scientific Research (No. 11878104)
from the Ministry of Education, Science and Culture of
J apan.
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
spectra for natural and synthetic compound 1, and 1H NMR
spectra for 2, 3, and 1Z. This material is available free of
charge via the Internet at http://pubs.acs.org.
J O991338I