Determination of the absolute stereostructure of seco-macrosphelide E produced by a fungal strain from a sea hare.

Article abstract of DOI:10.1248/cpb.50.303

seco-Macrosphelide E has been isolated from a strain of Periconia byssoides originally separated from the sea hare Aplysia kurodai. Its absolute stereostructure, with the same configuration as that of macrosphelide E, have been elucidated on the basis of

Full text of DOI:10.1248/cpb.50.303

February 2002
Notes
Chem. Pharm. Bull. 50(2) 303—306 (2002)
303
Determination of the Absolute Stereostructure of seco-Macrosphelide E
Produced by a Fungal Strain from a Sea Hare
a
a
b
b
,a
*
Hiroshi NAKAMURA, Machiko ONO, Takeshi YAMADA, Atsushi NUMATA, and Hiroyuki AKITA
School of Pharmaceutical Sciences, Toho University,a 2–2–1 Miyama, Funabashi, Chiba 274–8510, Japan and Osaka
University of Pharmaceutical Sciences,b Nasahara, Takatsuki, Osaka 569–1094, Japan.
Received September 19, 2001; accepted November 26, 2001
seco-Macrosphelide E has been isolated from a strain of Periconia byssoides originally separated from the
sea hare Aplysia kurodai. Its absolute stereostructure, with the same configuration as that of macrosphelide E,
have been elucidated on the basis of spectroscopic analyses and unambiguous synthesis.
Key words seco-macrosphelide E; structure elucidation; total synthesis; Keck condensation
As part of our continuing search for antitumor metabolites
from marine microorganisms, we have previously isolated
pericosine A as an anticancer material and five 16-membered
macrolides, macrosphelides E (1)-I, as cell adhesion in-
hibitors from a strain of Periconia byssoides OUPS-N133
originally separated from the sea hare Aplysia kurodai.1)
Macrosphelide E (1) has been found to be the C-3 stereoiso-
mer of macrosphelide A (3) which had been isolated as a cell
adhesion inhibitor from a strain of Microsphaeropsis sp. by
Omura and co-workers.2) In addition, it inhibited the adhe-
sion of human-leukemia HL-60 cells to human-umbilical-
vein endothelial cells (HUVEC) potently as macrosphelide A
(3) did. Total syntheses of these metabolites 1 and 3 were
achieved by three research groups involving our group.3) Fur-
ther investigation of the secondary metabolites of this fungal
strain led to the isolation of the straight-chain triester 2 des-
ignated as seco-macrosphelide E. Now we report the deter-
mination of the absolute stereostructure for seco-macrosphe-
lide E (2) based on spectroscopic analysis and unambiguous
synthesis.
stants (J6,7ϭ15.7 Hz, J12,13ϭ15.6 Hz) of the olefinic protons.
The connection of these three units and the remaining ester
moieties was determined on the basis of the key heteronu-
clear multiple bond connectivity (HMBC) correlation sum-
marized in Fig. 1, and the planar structure of 2 was eluci-
dated.
The absolute stereostructure for seco-macrosphelide E is
assumed to be either 3R-isomer 2 or 3S-isomer 4, since 2 is
considered to be a precursor of macrosphelides E (1) or A
(3). We have therefore achieved synthesis of both these di-
astereisomers 2 and 4 in order to resolve the stereochemistry
for the natural product.
We reported that the enantioselective hydrolysis of (Ϯ)-
(4,5)-anti-5-acetoxy-4-benzyloxy-2(E)-hexenoate 5 using the
lipase “Amano P” from Pseudomonas sp. in phosphate buffer
solution gave the (4R,5S)-5-acetoxy ester 5 (Ͼ99% ee, 48%
yield) and the (4S,5R)-5-hydroxy ester 6 (Ͼ99% ee, 44%
yield), and methanolysis of (4R,5S)-5 provided the (4R,5S)-6
in 84% yield.4) The key compound in the synthesis of (ϩ)-1
and (ϩ)-3 is (4R,5S)-4-benzyloxy-5-silyloxy-2(E)-hexenoic
acid 7 and this compound was also used for the synthesis
of 2 or 4 as a starting material. Condensation of carboxylic
acid (4R,5S)-7 and commercially available (3R)-hydroxy
butanoate 8 via the Keck procedure5) (dicyclohexylcarbo-
diimide (DCC), 4-(dimethylamino)pyridine (DMAP), cam-
phorsulfonic acid (CSA)) provided diester (3R,8R,9S)-9
([a]D Ϫ23.1° (cϭ0.8, CHCl3)) in 64% yield, which was desi-
seco-Macrosphelide (2) had the molecular formula
C16H23O8 established by the [M]ϩ peak of 2 in high resolu-
tion (HR)-EI-MS. Its IR spectrum exhibited bands at 3429,
1718, 1665 and 1647 cmϪ1, characteristic of hydroxy and
carbonyl groups, and a double bond. A close inspection of
the 1H- and 13C-NMR spectra of 2 by distortionless enhance-
ment by polarization transfer (DEPT) and 1H–13C correlation
spectroscopy (COSY) experiments revealed the presence of
three secondary methyls, one sp3-hybridized methylene, five
oxygen-bearing sp3-methines including three hydroxyme-
thines, two 1, 2-disubstituted double bonds, one methoxyl
1
group and three ester carbonyl groups. The H–1H COSY
analysis of 2 led to three partial structural units as shown by
bold-faced lines in Fig. 1. The E-geometry of both the D6-
and D12-double bonds was deduced from the coupling con-
Fig. 1. Typical 2D NMR Correlations in seco-Macrosphelide (2)
Chart 1
To whom correspondence should be addressed. e-mail: akita@phar.toho-u.ac.jp
© 2002 Pharmaceutical Society of Japan

304
Vol. 50, No. 2
Chart 2
Chart 3
(1H-NMR, 13C-NMR, [d]D and MS) of (3R,8R,9S,14R,15S))-
2 and (3S,8R,9S,14R,15S)-4 quite resembled those of the nat-
ural product 2, respectively, while both retention times of
(3R,8R,9S,14R,15S)-2 (tRϭ19.3 min) and (3S,8R,9S,14R,
15S)-4 (tRϭ25.8 min) by mean of HPLC (column; CHIRAL-
CEL OD (0.46ϫ25 cm), solvent; n-hexane–EtOH (10 : 1);
detection; 254 nm) were quite different. The retention time of
(3R,8R,9S,14R,15S)-2 was found to be consistent with that
(tRϭ19.3 min) of the natural product 2.
In conclusion, absolute structure of the natural product
2 was found to be methyl (3R,8R,9S,14R,15S)-8,14,15-tri-
hydroxy-3,9-dimethyl-5,11-dioxo-4,10-dioxahexadeca-
(6E,12E)-dienoate in comparison with unambiguouly syn-
thesized (3R,8R,9S,14R,15S)-2. The absolute configurations
due to five chiral centers in 2 were the same as those of
macrosphelide E (1).
lylated to yield a hydroxy-diester (3R,8R,9S)-10 ([a]D
Ϫ26.5° (cϭ0.71, CHCl3)) in 62% yield. Second condensa-
tion of carboxylic acid (4R,5S)-7 and (3R,8R,9S)-10 via the
Keck procedure4) afforded triester (3R,8R,9S,14R,15S)-11
([a]D Ϫ35.6° (cϭ0.74, CHCl3)) in 57% yield, which was
desilylated to yield a hydroxy-triester (3R,8R,9S,14R,15S)-12
([a]D Ϫ64.3° (cϭ0.43, CHCl3)) in 51% yield. Deprotection
of benzyl group in (Ϫ)-12 using AlCl3 in the presence of m-
xylene4) gave trihydroxy-triester (3R,8R,9S,14R,15S)-2 ([a]D
ϩ40.0° (cϭ0.18, EtOH)) in 46% yield. The synthesis of
(3S,8R,9S,14R,15S)-4 was carried out by the way as for the
preparatiom of (3R,8R,9S,14R,15S)-2. Condensation of car-
boxylic acid (4R,5S)-7 and commercially available (3S)-
hydroxy butanoate 8 via the Keck procedure gave diester
(3S,8R,9S)-13 ([a]D Ϫ9.1° (cϭ0.7, CHCl3)) in 75% yield,
which was desilylated to yield a hydroxy-diester (3S,8R,9S)-
14 ([a]D Ϫ42.5° (cϭ0.54, CHCl3)) in 86% yield. Second
condensation of carboxylic acid (4R,5S)-7 and (3S,8R,9S)-14
via the Keck procedure afforded triester (3S,8R,9S,14R,15S)-
15 ([a]D Ϫ22.9° (cϭ0.5, CHCl3)) in 69% yield, which was
desilylated to yield a hydroxy-triester (3S,8R,9S,14R,15S)-16
([a]D Ϫ44.9° (cϭ0.54, CHCl3)) in 76% yield. Deprotection
of benzyl group in (Ϫ)-16 using AlCl3 in the presence of m-
xylene gave trihydroxy-triester (3S,8R,9S,14R,15S)-4 ([a]D
Experimental
1H- and 13C-NMR spectra were recorded on JEOL AL 400 or Varian
UNITY INOVA-500 spectrometers in CDCl3. Carbon substitution degrees
were established by DEPT pulse sequence. The fast atom bombardment
mass spectra (FAB-MS) were obtained with JEOL JMS-DX 303 and elec-
tron (impact) ionization mass spectra (EI-MS) were recorded a Hitachi M-
4000H spectrometer. IR spectra were recorded a JASCO FT/IR-300 spec-
trometer. Optical rotations were measured with a JASCO DIP-370 digital
polarimeter. All evaporations were performed under reduced pressure. For
ϩ57.2° (cϭ0.17, EtOH)) in 46% yield. Both physical data column chromatography, silica gel (Kieselgel 60) was employed.

February 2002
305
Jϭ12 Hz), 5.10 (1H, dq, Jϭ4, 6 Hz), 6.03 (1H, dd, Jϭ2, 16 Hz), 6.07 (1H,
dd, Jϭ2, 16 Hz), 6.85 (1H, dd, Jϭ6, 16 Hz), 6.90 (1H, dd, Jϭ2, 16 Hz),
7.22—7.36 (10H, m). Anal. Found: C, 66.73; H, 8.08. Calcd for C37H52O9Si:
C, 66.44; H, 7.84%.
Culturing and Isolation A strain of Periconia byssoides OUPS-N133,
separated from the sea hare Aplysia kurodai, was cultured at 27 °C for four
weeks in a liquid medium (90 l) containing malt extract 1%, glucose 1% and
peptone 0.05% in artificial seawater adjusted to pH 7.5. As reported previ-
ously,1b) the AcOEt extract (5.7 g) of the culture filtrate was successively
chromatographed on Sephadex LH-20 (CH2Cl2–MeOH, 1 : 1) and silica gel
(CH2Cl2/MeOH). The MeOH–CH2Cl2 (1 : 19) eluate (315.7 mg) from silica
gel column chromatography was purified by HPLC using MeOH–H2O (1 : 1)
as the eluent to afford 2 (1.2 mg) as a colorless oil.
Desilylation of (3R,8R,9S,14R,15S)-11 A mixture of (3R,8R,9S,14R,
15S)-11 (0.809 g, 1.3 mmol) in the mixed solvent (AcOH (4.5 ml), H2O
(3 ml) and THF (3 ml)) was stirred for 12 h at 80 °C. The reaction mixture
was evaporated and the residue was diluted with H2O, extracted with Et2O.
The organic layer was washed with 7% aqueous NaHCO3 and dried
over MgSO4. The organic layer was evaporated to give a crude residue,
which was chromatographed on silica gel (20 g, n-hexane : AcOEtϭ5 : 1)
to give (3R,8R,9S,14R,15S)-12 (0.358 g, 51%) as a homogeneous oil.
(3R,8R,9S,14R,15S)-12; IR (neat): 3505, 1720 cmϪ1; [a]D23 Ϫ64.3° (cϭ0.43,
CHCl3); 1H-NMR: d: 1.14 (3H, d, Jϭ6 Hz), 1.28 (3H, d, Jϭ6 Hz), 1.32 (3H,
d, Jϭ6 Hz), 2.00 (1H, br s), 2.52, 2.68 (each 1H, dd, Jϭ6, 16 Hz), 3.66 (3H,
s), 3.89 (1H, ddd, Jϭ2, 6, 6 Hz), 3.90 (1H, dq, Jϭ4, 6 Hz), 4.07 (1H, ddd,
Jϭ2, 4, 6 Hz), 4.40, 4.48, 4.62, 4.63 (each 1H, d, Jϭ12 Hz), 5.09 (1H, dq,
Jϭ4, 6 Hz), 5.33 (1H, qt, Jϭ6, 6 Hz), 6.03 (1H, dd, Jϭ2, 16 Hz), 6.06 (1H,
dd, Jϭ2, 16 Hz), 6.84 (1H, dd, Jϭ6, 16 Hz), 6.90 (1H, dd, Jϭ6, 16 Hz),
7.24—7.36 (10H, m). 13C-NMR: d 15.2 (q), 18.1 (q), 20.0 (q), 40.6 (t), 51.8
(q), 67.7 (d), 69.2 (d), 71.4 (t), 71.6 (t), 71.7 (d), 79.5 (d), 82.0 (d), 124.0
(d), 124.2 (d), 127.4 (d), 127.6 (d), 127.6 (d), 127.7 (d), 128.2 (d), 128.3 (d),
137.4 (s), 137.4 (s), 144.0 (d), 144.5 (d), 164.6 (s), 164.7 (s), 170.3 (s).
FAB-MS m/z: 555 (Mϩϩ1); Anal. Found: C, 66.92; H, 7.16. Calcd for
C31H38O9: C, 67.13; H, 6.91%.
seco-Macrosphelide (2): A colorless oil, [d]D ϩ56.0° (c 0.10, EtOH); UV
lmax (EtOH) nm (log e): 215 (4.21); IR nmax (neat) cmϪ1: 3429 (OH), 1718
(ester), 1665, 1647 (CϭC); EI-MS m/z: 374 (Mϩ, 0.2%), 212 (28), 111 (99),
84 (100), 69 (5); HR-EI-MS m/z: 374.1564 (Mϩ) (Calcd for C16H23O8:
1
374.1575); H-NMR d ppm (CDCl3, 500 MHz): 1.19 (3H, d, Jϭ6.4 Hz, H-
16), 1.29 (3H, d, Jϭ6.6 Hz, 9-CH3), 1.34 (3H, d, Jϭ6.2 Hz, 3-CH3), 2.02
(1H, br s, 15-OH), 2.47 (1H, br s, 14-OH), 2.52 (1H, br s, 8-OH), 2.55 (1H,
dd, Jϭ15.5, 5.2 Hz, H-2A), 2.69 (1H, dd, Jϭ15.5, 6.2 Hz, H-2B), 3.69 (3H,
s, 1-OCH3), 3.99 (1H, br s, H-15), 4.33 (1H, br s, H-14), 4.45 (1H, br s, H-8),
5.10 (1H, qd, Jϭ6.6, 3.2 Hz, H-9), 5.34 (1H, quintet d, Jϭ6.2, 5.2 Hz, H-3),
6.12 (1H, dd, Jϭ15.7, 1.8 Hz, H-6), 6.15 (1H, dd, Jϭ15.6, 1.8 Hz, H-12),
6.91 (1H, dd, Jϭ15.7, 4.2 Hz, H-7), 6.99 (1H, dd, Jϭ15.6, 4.2 Hz, H-13);
13C-NMR d ppm (CDCl3, 125 MHz): 14.95 (C-16), 17.71 (9-CH3), 19.91 (3-
CH3), 40.64 (C-2), 51.87 (1-OCH3), 67.56 (C-3), 69.85 (C-15), 73.36 (C-8),
73.50 (C-9), 74.51 (C-14), 122.05 (C-12), 122.75 (C-6), 144.64 (C-7),
146.56 (C-13), 165.15 (C-5), 165.91 (C-11), 170.81 (C-1); CD l (c
2.68ϫ10Ϫ4 M in EtOH)/nm 296 (De 0), 248 (Ϫ0.34), 239 (0) and 214
(ϩ9.72).
Methyl (3R,8R,9S,14R,15S))-8,14,15-Hydroxy-3,9-dimethyl-5,11-dioxo-
4,10-dioxadeca (6E,12E)-Dienoate (2) To a mixture of AlCl3 (0.146
g, 1.1 mmol) in CH2Cl2 (2 ml) was added dropwise
a solution of
Methyl (3R,8R,9S)-8-Benzyloxy-9-tert-butyldimethylsiloxy-3-methyl-
5-oxo-4-oxadeca (6E)-Enoate (9) To a mixture of DCC (2.260 g, 11
mmol), DMAP (1.780 g, 14.6 mmol) and (ϩ)-CSA (1.700 g, 14.6 mmol) in
CH2Cl2 (45 ml) was added a solution of (4R,5S)-7 (2.546 g, 7.3 mmol) and
(3R)-8 (1.720 g, 14.6 mmol) in CH2Cl2 (20 ml) and the reaction mixture was
stirred for 3 d at room temperature. After the generated precipitate was fil-
tered off and the filtrate was washed with 2 M aqueous HCl and 7% aqueous
NaHCO3. The organic layer was dried over MgSO4 and evaporated to give a
crude residue, which was chromatographed on silica gel (110 g, n-
hexane : AcOEtϭ10 : 1) to give (3R,8R,9S)-9 (2.106 g, 64%) as a homoge-
nous oil. (3R,8R,9S)-9; IR (neat): 1743 cmϪ1; [a]D25 Ϫ23.1° (cϭ0.8, CHCl3);
1H-NMR: d: 0.00 (3H, s), 0.03 (3H, s), 0.85 (9H, s), 1.19 (3H, d, Jϭ6 Hz),
1.32 (3H, d, Jϭ6 Hz), 2.52, 2.69 (each 1H, dd, Jϭ6, 16 Hz), 3.66 (3H, s),
3.75 (1H, dt, Jϭ2, 6 Hz), 3.80 (1H, qd, Jϭ6 Hz), 4.42, 4.59 (each 1H, d,
Jϭ12 Hz), 5.33 (1H, dq, Jϭ6 Hz), 5.99 (1H, dd, Jϭ2, 16 Hz), 6.90 (1H, dd,
Jϭ6, 16 Hz), 7.23—7.36 (5H, m). FAB-MS m/z: 451 (Mϩϩ1); Anal. Found:
C, 63.67; H, 8.45. Calcd for C24H38O6Si: C, 63.97; H, 8.50%.
Desilylation of (3R,8R,9S)-9 A mixture of (Ϫ)-9 (1.758 g, 3.9 mmol) in
the mixed solvent (AcOH (7.5 ml), H2O (5 ml) and THF (5 ml)) was stirred
for 12 h at 80 °C. The reaction mixture was evaporated and the residue was
diluted with H2O, extracted with Et2O. The organic layer was washed with
7% aqueous NaHCO3 and dried over MgSO4. The organic layer was evapo-
rated to give a crude residue, which was chromatographed on silica gel
(25 g, n-hexane : AcOEtϭ5 : 1) to give (3R,8R,9S)-10 (0.822 g, 62%) as a
homogeneous oil. (3R,8R,9S)-10; IR (neat): 3484, 1722 cmϪ1; [a]D26 Ϫ26.5°
(cϭ0.71, CHCl3); 1H-NMR: d: 1.12 (3H, d, Jϭ6 Hz), 1.32 (3H, d, Jϭ6 Hz),
2.51—2.63 (1H, br s), 2.52, 2.68 (each 1H, dd, Jϭ6, 16 Hz), 3.65 (3H, s),
3.89 (1H, ddd, Jϭ2, 4, 6 Hz), 3.92 (1H, qd, Jϭ4, 6 Hz), 4.39, 4.61 (each 1H,
d, Jϭ12 Hz), 5.32 (1H, dq, Jϭ6 Hz), 6.00 (1H, dd, Jϭ2, 16 Hz), 6.86 (1H,
dd, Jϭ6, 16 Hz), 7.23—7.38 (5H, m). FAB-MS m/z: 337 (Mϩϩ1); Anal.
Found: C, 63.85; H, 7.32. Calcd for C18H24O6: C, 64.27; H, 7.19%.
(3R,8R,9S,14R,15S)-12 (0.060 g, 0.11 mmol) and m-xylene (1 ml) at
Ϫ20 °C, and the reaction mixture was stirred for 1 h at 0 °C. The reaction
mixture was diluted with saturated brine and extracted with Et2O. The or-
ganic layer was dried over MgSO4 and evaporated to give a crude residue,
which was subjected to preparative SiO2 thin layer chromatography (n-
hexane : AcOEtϭ4 : 1) to give (3R,8R,9S,14R,15S)-2 (0.017 g, 46%) as col-
orless oil. (3R,8R,9S,14R,15S)-2; IR (KBr): 3438, 1708 cmϪ1; [a]D23 ϩ40.0°
(cϭ0.18, EtOH); HR-MS (FAB-MS, matrix: m-nitrobenzyl alcohol (NBA)):
1
Calcd for C17H27O9 (Mϩϩ1) 375.1655; Found 375.1649. H-NMR and 13C-
NMR data of (3R,8R,9S,14R,15S)-2 were identical with those of the natural
product 2.
Methyl (3S,8R,9S)-8-Benzyloxy-9-tert-butyldimethylsiloxy-3-methyl-
5-oxo-4-oxadeca (6E)-Enoate (13) To a mixture of DCC (3.030 g,
14.7 mmol), DMAP (2.390 g, 19.6 mmol) and (ϩ)-CSA (2.280 g, 9.8 mmol)
in CH2Cl2 (50 ml) was added a solution of (4R,5S)-7 (3.425 g, 9.8 mmol)
and (3S)-8 (2.310 g, 19.6 mmol) in CH2Cl2 (20 ml) and the reaction mixture
was stirred for 2 d at room temperature. After the generated precipitate was
filtered off and the filtrate was washed with 2 M aqueous HCl and 7% aque-
ous NaHCO3. The organic layer was dried over MgSO4 and evaporated to
give a crude residue, which was chromatographed on silica gel (200 g, n-
hexane : AcOEtϭ20 : 1) to give (3S,8R,9S)-13 (3.316 g, 75%) as a homoge-
nous oil. (3S,8R,9S)-13; IR (neat): 2953, 1743, 1722 cmϪ1; [a]D22 Ϫ9.1°
1
(cϭ0.7, CHCl3); H-NMR: d: 0.00 (3H, s), 0.02 (3H, s), 0.84 (9H, s), 1.18
(3H, d, Jϭ6 Hz), 1.32 (3H, d, Jϭ6 Hz), 2.56, 2.69 (each 1H, dd, Jϭ6,
16 Hz), 3.65 (3H, s), 3.73 (1H, ddd, Jϭ2, 6 Hz), 3.80 (1H, dq, Jϭ6, 6 Hz),
4.42, 4.58 (each 1H, d, Jϭ12 Hz), 5.33 (1H, sixtet, Jϭ6 Hz), 5.98 (1H, dd,
Jϭ2, 16 Hz), 6.88 (1H, dd, Jϭ6, 16 Hz), 7.23—7.35 (5H, m). FAB-MS m/z:
451 (Mϩϩ1); Anal. Found: C, 64.02; H, 8.69. Calcd for C24H38O6Si: C,
63.97; H, 8.50%.
Desilylation of (؊)-13 A mixture of (3S,8R,9S)-13 (3.139 g, 7 mmol) in
the mixed solvent (AcOH (15 ml), H2O (10 ml) and THF (10 ml)) was stirred
for 12 h at 80 °C. The reaction mixture was evaporated and the residue was
diluted with H2O, extracted with Et2O. The organic layer was washed with
7% aqueous NaHCO3 and dried over MgSO4. The organic layer was evapo-
rated to give a crude residue, which was chromatographed on silica gel
(50 g, n-hexane : AcOEtϭ5 : 1) to give (3S,8R,9S)-14 (2.031 g, 86%) as a ho-
mogeneous oil. (3S,8R,9S)-14; IR (neat): 3483, 1721 cmϪ1; [a]D22 Ϫ42.5°
(cϭ0.54, CHCl3); 1H-NMR: d: 1.14 (3H, d, Jϭ6 Hz), 1.34 (3H, d, Jϭ6 Hz),
2.32 (1H, br s), 2.54, 2.70 (each 1H, dd, Jϭ6, 16 Hz), 3.66 (3H, s), 3.91—
3.97 (1H, m), 3.88—3.92 (1H, m), 4.41, 4.63 (each 1H, d, Jϭ12 Hz), 5.34
(1H, sixtet, Jϭ6 Hz), 6.03 (1H, dd, Jϭ2, 16 Hz), 6.89 (1H, dd, Jϭ6, 16 Hz),
7.25—7.37 (5H, m). FAB-MS m/z: 337 (Mϩϩ1); Anal. Found: C, 63.43; H,
7.17. Calcd for C18H24O6: C, 64.27; H, 7.19%.
Methyl (3R,8R,9S,14R,15S))-8,14-Dibenzyloxy-15-tert-butyldimethyl-
siloxy-3,9-dimethyl-5,11-dioxo-4,10-dioxadeca (6E,12E)-Dienoate (11)
To a mixture of DCC (0.760 g, 3.7 mmol), DMAP (0.600 g, 4.9 mmol) and
(ϩ)-CSA (0.570 g, 2.5 mmol) in CH2Cl2 (30 ml) was added a solution of
(3R,8R,9S)-10 (0.822 g, 2.5 mmol) and (4R,5S)-7 (1.620 g, 4.6 mmol) in
CH2Cl2 (10 ml) and the reaction mixture was stirred for 12 h at room tem-
perature. After the generated precipitate was filtered off and the filtrate was
washed with 2 M aqueous HCl and 7% aqueous NaHCO3. The organ-
ic layer was dried over MgSO4 and evaporated to give a crude residue,
which was chromatographed on silica gel (40 g, n-hexane : AcOEtϭ10 : 1)
to give (3R,8R,9S,14R,15S)-11 (0.889 g, 57%) as a homogenous oil.
(3R,8R,9S,14R,15S)-11; IR (neat): 1732 cmϪ1; [a]D23 Ϫ35.6° (cϭ0.74,
1
CHCl3); H-NMR: d: 0.01 (3H, s), 0.03 (3H, s), 0.85 (9H, s), 1.19 (3H, d,
Methyl (3S,8R,9S,14R,15S))-8,14-Dibenzyloxy-15-tert-butyldimethyl-
siloxy-3,9-dimethyl-5,11-dioxo-4,10-dioxadeca (6E,12E)-Dienoate (15)
To a mixture of DCC (1.700g, 8.2 mmol), DMAP (1.340 g, 10.9 mmol) and
Jϭ6 Hz), 1.27 (3H, d, Jϭ6 Hz), 1.33 (3H, d, Jϭ6 Hz), 2.52, 2.69 (each 1H,
dd, Jϭ6, 16 Hz), 3.66 (3H, s), 3.77 (1H, ddd, Jϭ2, 6, 6 Hz), 3.84 (1H, dq,
Jϭ6 Hz), 4.11 (1H, ddd, Jϭ2, 4, 6 Hz), 4.44, 4.49, 4.60, 4.63 (each 1H, d,

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Vol. 50, No. 2
(ϩ)-CSA (1.280 g, 5.5 mmol) in CH2Cl2 (40 ml) was added a solution of 14R,15S)-16 (0.055 g, 0.1 mmol) and m-xylene (1 ml) at Ϫ20 °C and the re-
(3S,8R,9S)-14 (1.900 g, 5.7 mmol) and (4R,5S)-7 (1.930 g, 5.5 mmol) in action mixture was stirred for 1 h at 0 °C. The reaction mixture was diluted
CH2Cl2 (10 ml) and the reaction mixture was stirred for 48 h at room tem- with saturated brine and extracted with Et2O. The organic layer was dried
perature. After the generated precipitate was filtered off and the filtrate over MgSO4 and evaporated to give a crude residue, which was subjected to
was washed with 2
M aqueous HCl and 7% aqueous NaHCO3. The organ- preparative SiO2 thin layer chromatography (n-hexane : AcOEtϭ4 : 1) to give
ic layer was dried over MgSO4 and evaporated to give a crude residue, (3S,8R,9S,14R,15S)-4 (0.017 g, 46%) as colorless oil. (3S,8R,9S,14R,15S)-
which was chromatographed on silica gel (50 g, n-hexane : AcOEtϭ10 : 1) 4; IR (KBr): 3438, 1708 cmϪ1; [a]D22 ϩ57.2° (cϭ0.17, EtOH); 1H-NMR: d:
to give (3S,8R,9S,14R,15S)-15 (2.554 g, 69%) as a homogenous oil. 1.14 (3H, d, Jϭ6 Hz), 1.23 (3H, d, Jϭ6 Hz), 1.31 (3H, d, Jϭ6 Hz), 2.52,
(3S,8R,9S,14R,15S)-15; IR (neat): 2932, 1722 cmϪ1; [a]D25 Ϫ22.9° (cϭ0.5, 2.66 (each 1H, dd, Jϭ6, 16 Hz), 3.65 (3H, s), 3.92 (1H, dq, Jϭ4, 6 Hz), 4.25
1
CHCl3); H-NMR: d: 0.02 (3H, s), 0.04 (3H, s), 0.86 (9H, s), 1.20 (3H, d,
(1H, ddd, Jϭ2, 4, 6 Hz), 4.41 (1H, ddd, Jϭ2, 4, 6 Hz), 5.04 (1H, dq, Jϭ4,
Jϭ6 Hz), 1.28 (3H, d, Jϭ6 Hz), 1.35 (3H, d, Jϭ6 Hz), 2.54, 2.71 (each 1H, 6 Hz), 5.30 (1H, qt, Jϭ6, 6 Hz), 6.09 (1H, dd, Jϭ2, 16 Hz), 6.10 (1H, dd,
dd, Jϭ6, 16 Hz), 3.68 (3H, s), 3.78 (1H, ddd, Jϭ2, 6, 6 Hz), 3.85 (1H, dq, Jϭ2, 16 Hz), 6.88 (1H, dd, Jϭ6, 16 Hz), 6.96 (1H, dd, Jϭ6, 16 Hz). 13C-
Jϭ6, 6 Hz), 4.11—4.15 (1H, m), 4.45, 4.51, 4.61, 4.63 (each 1H, d, NMR: d 14.8 (q), 17.8 (q), 20.0 (q), 40.6 (t), 52.0 (q), 67.7 (d), 70.0 (d),
Jϭ12 Hz), 5.12 (1H, dq, Jϭ4, 6 Hz), 5.35 (1H, sixtet, Jϭ6, 16 Hz), 6.04 72.8 (d), 73.2 (d), 74.6 (d), 121.8 (d), 122.5 (d), 145.0 (d), 146.6 (d), 165.2
(1H, dd, Jϭ2, 16 Hz), 6.08 (1H, dd, Jϭ2, 16 Hz), 6.87 (1H, dd, Jϭ6, 16 Hz), (s), 165.7 (s), 170.6 (s). HR-MS (FAB-MS, matrix: m-nitrobenzyl alcohol
6.91 (1H, dd, Jϭ6, 16 Hz), 7.24—7.36 (10H, m). Anal. Found: C, 66.87; H, (NBA)): Calcd for C17H27O9 (Mϩϩ1) 375.1655; Found 375.1684.
7.89. Calcd for C37H52O9Si: C, 66.44; H, 7.84%.
Desilylation of (3S,8R,9S,14R,15S)-15 A mixture of (3S,8R,9S,14R,
Acknowledgement The authors are grateful to Professor Yoshiteru Ida,
15S)-15 (2.370 g, 3.5 mmol) in the mixed solvent (AcOH (8 ml), H2O (5 ml) School of Pharmaceutical Sciences, Showa University for measurement of
and THF (5 ml)) was stirred for 12 h at 80 °C. The reaction mixture was high resolution mass spectra (FAB-MS) of synthetic (3R,8R,9S,14R,15S)-2
evaporated and the residue was diluted with H2O, extracted with Et2O. and (3S,8R,9S,14R,15S)-4.
The organic layer was washed with 7% aqueous NaHCO3 and dried
over MgSO4. The organic layer was evaporated to give a crude residue, References
which was chromatographed on silica gel (20 g, n-hexane : AcOEtϭ5 : 1)
to give (3S,8R,9S,14R,15S)-16 (1.482 g, 76%) as a homogeneous oil.
(3S,8R,9S,14R,15S)-16; IR (neat): 3505, 1720, 1657 cmϪ1; [a]D25 Ϫ44.9°
(cϭ0.54, CHCl3); 1H-NMR: d: 1.15 (3H, d, Jϭ6 Hz), 1.30 (3H, d, Jϭ6 Hz),
1.34 (3H, d, Jϭ6 Hz), 2.28 (1H br s), 2.54, 2.70 (each 1H, dd, Jϭ6, 16 Hz),
3.67 (3H, s), 3.93 (1H, ddd, Jϭ2, 4, 6 Hz), 3.96 (1H, dq, Jϭ4, 6 Hz), 4.11
(1H, ddd, Jϭ2, 4, 6 Hz), 4.42, 4.49, 4.65, 4.65 (each 1H, d, Jϭ12 Hz), 5.11
(1H, qd, Jϭ4, 6 Hz), 5.35 (1H, sixtet, Jϭ6 Hz), 6.06 (1H, dd, Jϭ2, 16 Hz),
6.08 (1H, dd, Jϭ2, 16 Hz), 6.86 (1H, dd, Jϭ6, 16 Hz), 6.91 (1H, dd, Jϭ6,
16 Hz), 7.24—7.38 (10H, m). 13C-NMR: d 15.2 (q), 18.2 (q), 20.0 (q), 40.6
(t), 51.8 (q), 67.7 (d), 69.2 (d), 71.4 (t), 71.6 (t), 71.7 (d), 79.4 (d), 81.9 (d),
124.0 (d), 124.2 (d), 127.4 (d), 127.6 (d), 127.6 (d), 127.7 (d), 128.2 (d),
128.3 (d), 137.4 (s), 137.4 (s), 144.0 (d), 144.6 (d), 164.7 (s), 164.7 (s),
170.3 (s). FAB-MS m/z: 555 (Mϩϩ1); Anal. Found: C, 66.83; H, 6.90. Calcd
for C31H38O9: C, 67.13; H, 6.91%.
1) a) Numata A., Iritani M., Yamada T., Minoura K., Matsumura E.,
Yamori T., Tsuruo T., Tetrahedron Lett., 38, 8215—8218 (1997); b)
Yamada T., Iritani M., Doi M., Minoura K., Ito T., Numata A., J.
Chem. Soc. Perkin Trans 1, 2001, 3046—3053.
2) a) Hayashi M., Kim Y.-P., Hiraoka H., Natori M., Takamatsu S.,
Kawakubo T., Masuma R., Komiyama K., Omura S., J. Antibiot., 48,
1435—1439 (1995); b) Takamatsu S., Kim Y.-P., Hayashi M., Hiraoka
H., Natori M., Komiyama K., Omura S., ibid., 49, 95—98 (1996).
3) a) Sunazuka T., Hirose T., Harigaya Y., Takamatsu S., Hayashi M.,
Komiyama K., Omura S., Sprengeler P., A., Smith A. B., III, J. Am.
Chem. Soc., 119, 10247—10248 (1997); b) Kobayashi Y., Kumar B.
G., Kurachi T., Tetrahedron Lett., 41, 1559—1563 (2000); c) Ono M.,
Nakamura H., Konno F., Akita H., Tetrahedron:Asymmetry, 11,
2753—2764 (2000).
4) Ono M., Saotome C., Akita H., Tetrahedron:Asymmetry, 7, 2595—
2602 (1996).
5) Boden E. P., Keck G. E., J. Org. Chem., 50, 2394—2395 (1985).
Methyl (3S,8R,9S,14R,15S)-8,14,15-Hydroxy-3,9-dimethyl-5,11-dioxo-
4,10-dioxadeca (6E,12E)-Dienoate (4) To a mixture of AlCl3 (0.130 g,
1.0 mmol) in CH2Cl2 (2 ml) was added dropwise a solution of (3S,8R,9S,