Total syntheses of symbioramide derivatives from L-serine and their antileukemic activities

Article abstract of DOI:10.1021/jo0206824

Naturally occurring symbioramide, (2S,3R,2′R,3′E)-N-(2′-hydroxy-3′-octadecenoyl)- dihydrosphingosine 1a, was synthesized from D-erythro-dihydrosphingosine (amino part, 2) and (2R,3E)-2hydroxy-3-octadecenoic acid (acid part, 3a), both of which were prepared from L-serine. Its diastereomer, (2S,3R,2′S,3′E)-1b, having an enantiomer of the unnatural-type acid part that was prepared from D-mannitol, and its corresponding (Z)-isomers, (2S,3R,2′R,3′Z)-1c and (2S,3R,2′S,3′Z)1d, were also prepared. The antileukemic activities of 1a-d against HL-60 and L-1210 cells were appreciated by a MTT assay. None of the four symbioramide derivatives showed antileukemic activities in HL-60 cells. In L-1210 cells, all the symbioramide derivatives showed moderate antileukemic activities. Compound 1d had the most effective activity against L-1210 cells among the four derivatives. The data suggest that unnatural types of (2′S)-isomers of acid parts are more active than those of (2′R)-isomers.

Full text of DOI:10.1021/jo0206824

Tota l Syn th eses of Sym bior a m id e Der iva tives fr om L-Ser in e a n d
Th eir An tileu k em ic Activities
Hideki Azuma,* Ryoko Takao, Hayato Niiro, Keiji Shikata, Seizo Tamagaki,
Taro Tachibana, and Kenji Ogino*
Department of Applied & Bioapplied Chemistry, Graduate School of Engineering, Osaka City University,
Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, J apan
ogino@bioa.eng.osaka-cu.ac.jp
Received November 4, 2002
Naturally occurring symbioramide, (2S,3R,2′R,3′E)-N-(2′-hydroxy-3′-octadecenoyl)-dihydrosphin-
gosine 1a , was synthesized from D-erythro-dihydrosphingosine (amino part, 2) and (2R,3E)-2-
hydroxy-3-octadecenoic acid (acid part, 3a ), both of which were prepared from L-serine. Its
diastereomer, (2S,3R,2′S,3′E)-1b, having an enantiomer of the unnatural-type acid part that was
prepared from D-mannitol, and its corresponding (Z)-isomers, (2S,3R,2′R,3′Z)-1c and (2S,3R,2′S,3′Z)-
1d , were also prepared. The antileukemic activities of 1a -d against HL-60 and L-1210 cells were
appreciated by a MTT assay. None of the four symbioramide derivatives showed antileukemic
activities in HL-60 cells. In L-1210 cells, all the symbioramide derivatives showed moderate
antileukemic activities. Compound 1d had the most effective activity against L-1210 cells among
the four derivatives. The data suggest that unnatural types of (2′S)-isomers of acid parts are more
active than those of (2′R)-isomers.
In tr od u ction
or acidic sphingomyelinase via the so-called sphingomy-
elin cycle6 in response to various extracellular agents and
stress such as the antibody against FAS,7 tumor necrosis
factor R (TNF-R),8 and ionizing radiation.9 Although the
downstream of ceramide signaling is still not known,
ceramide-induced apoptosis has been well characterized.
Another recent advancement in sphingolipid research
was the identification of lipid microdomains, so-called
“rafts”.10 Membrane sphingolipids such as sphingomyelin
and glycosphingolipids constitute the microdomains by
clustering cholesterol, glycosylphosphatidylinositol-an-
chored proteins, and membrane-associated proteins.
In 1988, a new type of bioactive ceramide, symbiora-
mide (1a ) was isolated from the laboratory-cultured
dinoflagellate Symbiodium sp. obtained from the insides
of gill cells of an Okinawan bivalve Fragum sp. by
Kobayashi et al.11 They also reported that symbioramide
increased the sarcoplasmic reticulum Ca2+-ATPase ac-
tivity, which was the first example from marine sources,
and also exhibited antileukemic activity against L-1210
murine leukemia cells in vitro (IC50 ) 9.5 µg/mL).12
Symbioramide is composed of D-erythro-dihydrosphin-
gosine (2) as the amino part and (2R,3E)-2-hydroxy-3-
octadecenoic acid (3a ) as the acid part. Recently, a fatty
Sphingolipids and glycosphingolipids are ubiquitous
membrane components of essentially all eukaryotic cells
and serve physiologically important roles in bioorgan-
isms.1 Sphingolipids are structurally formed from three
units: a sphingoid base, a fatty acid, and a polar
headgroup. Recent studies have shown that sphingolipids
exert an important function as intracellular second
messengers in the regulation of cell growth,2,3 differentia-
tion,3,4 and programmed cell death (apoptosis).3,5 Cera-
mide, a metabolite or a precursor of sphingolipids, is an
important molecule in the second messenger role of
sphingolipid signaling. Ceramide is generated by neutral
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10.1021/jo0206824 CCC: $25.00 © 2003 American Chemical Society
Published on Web 03/04/2003
2790
J . Org. Chem. 2003, 68, 2790-2797

Total Syntheses of Symbioramide Derivatives
SCHEME 1. Syn th etic P la n for th e P r ep a r a tion of Sym bior a m id e (1a ) a n d th e Str u ctu r es of Th r ee
Dia ster eom er s (1b-d ) of 1a
acid variant of symbioramide, symbioramide-C16, was
isolated from a different Symbiodinium sp.13 R-Hydroxy-
â,γ-unsaturated carboxylic acids are a unique structure
in the natural product, because this type of acid is not
involved in biosynthesis and degradation of the usual
fatty acids.
Several methods for the preparation of 2 have been
published,14 and more recently, we reported a synthetic
method of preparing 2 from L-serine as a starting
material using Wittig olefination followed by asymmetric
epoxidation.15
the (Z)-configuration, 3c and 3d , respectively, were also
prepared. Four symbioramide derivatives (1a -d ) con-
taining these four acid parts were obtained, respectively,
and the ability of these compounds to induce cell death
in two leukemia cell lines (HL-60 and L-1210 cells) was
assessed by MTT assay. We aim to elucidate the struc-
ture-activity relationships in ceramide-mediated apop-
tosis.
Resu lts a n d Discu ssion
We focused our attention on protected (Z)-2-hydroxy-
3-octadecen-1-ol species for acid parts since they are
readily formed by the Wittig olefination of aldehydes from
L-serine and D-mannitol with a Wittig reagent. And their
related (E)-isomers could be prepared by photoisomer-
ization of (Z)-derivatives in the presence of a sensitizer.
I. Na tu r a l-Typ e Acid P a r t. The synthetic approach
to natural acid part 3a is outlined in Scheme 2. The first
approach is to convert the amino group of L-serine to the
secondary hydroxy group without inversion at the center
by the diazotization process. The preparation of chiral
1,2-dihydroxyester 4 was accomplished by a method
reported in the literature21 in 82% yield. Subsequent
protections of the primary hydroxyl group of 4 with tert-
butyldimethylsilyl chloride (TBDMSCl) and then the
remaining secondary hydroxyl group with chloromethyl
methyl ether (MOMCl) gave 6 in 67% yield (two steps),
which was reduced with DIBALH at -78 °C in toluene
to produce aldehyde 7 in 84% yield. The Wittig olefination
of 7 with pentadecyltriphenylphosphonium bromide us-
ing n-BuLi as a base at -78 °C in THF gave the olefin
R-Z-8 (J ) 11.2 Hz) as the sole product in 58% yield {-
[R]25D -60.6 (c 1.46, CHCl3)}. The use of freshly prepared
lithium hexamethyldisilazide (LHMDS, from n-BuLi and
NH(SiMe3)2 or sodium hexamethyldisilazide (NaHMDS))
as the base resulted in a slightly lower yield (42-44%)
The asymmetric total syntheses of 3a and 3b have been
carried out starting from two kinds of the chiral glycer-
aldehydes by Nakagawa et al., and 1a has been com-
pletely configured.16,17 Their method of preparing 3a is
convenient, but the method of (S)-glyceraldehyde prepa-
ration as a chiral component gave a low yield.18 Other
preparation methods of 3a and 3b have been reported.
Mori and co-worker19 synthesized 3a and 3b using
Sharpless asymmetric epoxidation of (E)-2-octadecen-1-
ol, and Sugimura et al.20 prepared 3a by reducing â,γ-
unsaturated R-oxo esters having a chiral auxiliary.
This report presents a new method for preparing the
natural-type acid part 3a from L-serine as the starting
material and a method for preparing the natural-type
amino part (2) (Scheme 1). The unnatural-type acid part
3b, an enantiomer of 3a , was also synthesized from
D-mannitol. Structural isomers of both 3a and 3b with
(13) Nakamura, H.; Kawase, Y.; Maruyama, K.; Murai, A. Bull.
Chem. Soc. J pn. 1998, 71, 781.
(14) a) Reist, E. J .; Christie, P. H. J . Org, Chem. 1970, 35, 3521. (b)
Roush, W. R.; Adam, M. A. J . Org, Chem. 1985, 50, 3752. (c) Sibi, M.
P.; Li, B. Tetrahedron Lett. 1992, 33, 4115.
(15) Azuma, H.; Tamagaki, S.; Ogino, K. J . Org. Chem. 2000, 65,
3538.
(16) Nakagawa, M.; Yoshida, J .; Hino, T. Chem. Lett. 1990, 1407.
(17) Yoshida, J .; Nakagawa, M.; Seki, H.; Hino, T. J . Chem. Soc.,
Perkin Trans. 1 1992, 343.
(18) Takano, S.; Numata, H.; Ogasawara, K. Heterocycles 1982, 19,
327.
(19) Mori, K.; Uenishi, K. Liebigs Ann. Chem. 1994, 41.
(20) Sugimura, H.; Yoshida, K. J . Org. Chem. 1993, 58, 4484.
(21) Mukaiyama, T.; Shiina, I.; Iwwadare, H.; Saitoh, M.; Nish-
imura, T.; Ohkawa, N.; Sakoh, H.; Nishimura, K.; Tani, Y.; Hasegawa,
M.; Yamada, K.; Saitoh, K. Chem. Eur. J . 1999, 5, 121.
J . Org. Chem, Vol. 68, No. 7, 2003 2791

Azuma et al.
SCHEME 2a
SCHEME 3
a
Conditions: (a) NaNO2, H2SO4, H2O, rt; then HC(OMe)3,
H2SO4, MeOH, 60 °C. (b) TBDMSCl, Et3N, cat. DMAP, CH2Cl2,
rt. (c) MOMCl, (i-Pr)2NEt, CH2Cl2, rt. (d) DIBALH, toluene, -78
°C. (e) C15H31PPh3Br, n-BuLi, THF, -78 °C. (f) Bu4NF, THF, 0
°C. (g) PhSSPh, hυ, cyclohexane-1,4-dioxane (3:1). (h) PDC, DMF,
40-50 °C.
a
Conditions: (a) C15H31PPh3Br, n-BuLi, -78 °C. (b) PhSSPh,
hυ, cyclohexane-dioxane (3:1). (c) H+, rt. (d) TBDMSCl, Et3N, cat.
DMAP, CH2Cl2, rt. (e) MOMCl, (i-Pr)2NEt, CH2Cl2, rt then Bu4NF,
THF, 0 °C. (f) PDC, DMF, 40-50 °C.
of olefin formation than the use of n-BuLi. The obtained
olefin R-Z-8 was photoisomerized using diphenyl disul-
fide (PhSSPh) as the sensitizer in a 1:3 v/v mixed solvent
of 1,4-dioxane and cyclohexane. The 1H NMR analysis
of this reaction mixture showed the presence of (E)- and
(Z)-olefins in a 74:26 ratio. Unfortunately, the separation
of these products and PhSSPh by column chromatogra-
phy was difficult; thus, the deprotection of R-Z-8 was
carried out before the photoisomerization. After removal
of the silyl protection, the resulting unsaturated primary
alcohol R-Z-9 was photoisomerized using the above
D-mannitol by a literature method.22 The photoisomer-
ization of Z-12 was carried out using the same method
described above. The H NMR analysis of this reaction
1
mixture showed the presence of (E)- and (Z)-olefins in a
91:9 ratio. The separation of (E)- and (Z)-isomers was
difficult by column chromatography; thus, the acetonide
groups of these isomers were deprotected by acid before
the purification. The obtained mixture of (E)- and (Z)-
1,2-diol isomers could not be separated, but after recrys-
tallization of the obtained crude solid, the mixture gave
pure S-E-13 in 69% yield based on Z-12. Two protections
of the primary hydroxy group with TBDMSCl and the
secondary hydroxy group with MOMCl followed by desi-
lylation produced the primary alcohol S-E-9 {[R]25D -80.9
(c 1.01, CHCl3)} in 65% yield based on S-E-13. This
alcohol was converted to the acid S-E-10 using the same
methodology for R-E-10. The isomer S-Z-10 was also
prepared without photoisomerization and obtained in
1
method. The H NMR analysis of this reaction mixture
showed the presence of (E)- and (Z)-olefins in a 76:24
ratio. Column chromatographic separation with n-hex-
ane-EtOAc (3:1) as an eluent and then recrystallization
of the obtained waxy solid with n-hexane gave pure R-E-9
(J ) 15.6 Hz) as a powdery solid in 55% yield {[R]25
D
-80.4 (c 1.24, CHCl3)}.
Finally, oxidation of R-E-9 with pyridinium dichromate
(PDC) in DMF provided the carboxylic acid R-E-10 in
78% yield. The protected MOM group of the obtained acid
was easily decomposed; thus, this protected acid was
immediately used in the next step of the amide formation
reaction. The isomer R-Z-10 was prepared using the
same methodology without photoisomerization and ob-
45% yield based on S-Z-13 {[R]25 +111.1 (c 1.36,
CHCl3)}.
D
III. Na tu r a l-Typ e Am in o P a r t (D-er yth r o-Dih y-
d r osp h in gosin e, 2). A synthetic method for preparing
D-erythro-dihydrosphingosine 2 from L-serine has been
reported15 (eight steps, 21% yield based on L-serine,
Scheme 4). The diol group of 2 was protected as an
acetonide to facilitate the next amide formation reaction.
Treatment of 2 with excess 2,2-dimethoxypropane and
tained in 69% yield based on R-Z-9 {[R]25 -116.1 (c
D
1.764, CHCl3)}.
II. Un n a tu r a l-Typ e Acid P a r t. The synthetic ap-
proach to unnatural acid part 3b is outlined in Scheme
3. The chiral acetonide Z-12 was readily prepared from
(22) Mulzer, J .; Brand, C. Tetrahedron 1986, 42, 5961.
2792 J . Org. Chem., Vol. 68, No. 7, 2003

Total Syntheses of Symbioramide Derivatives
SCHEME 4
F IGURE 1. MTT assay of L-1210 cells after treatment with
10 µM symbioramide derivative for 6 h.
a
Conditions: (a) C15H31PPh3Br, LiHMDS, THF, -78 °C. (b)
IV. Na tu r a l-Typ e Sym bior a m id e (1a ). Acid part
R-E-10 and amino part 19 were condensed to obtain a
natural type of symbioramide according to the method
of Nakagawa et al.17 This amide formation was success-
fully accomplished by the conventional method using
dicyclohexylcarbodiimide (DCC) in the presence of N-
hydroxybenzotriazole (HOBt) to give the full-protected
amide 20a as a solid in 79% yield. Two deprotection
reactions of the acetonide moiety with p-toluenesulfonic
acid and of the MOM group with BF3‚Et2O in EtSH
followed by recrystallization from acetone-benzene gave
a natural type of symbioramide 1a as a powdery solid
(two steps, 55%). The specific rotation value of our
synthetic 1a was [R]25D +1.19 (c 0.5, CHCl3) {natural 1a ,
m-CPBA, THF, rt. (c) Excess LiAlH4, Et2O, 0 °C. (d) TFA-H2O,
rt. (e) PPTS, (Me)2C(OMe)2, benzene, reflux.
SCHEME 5a
[R]19D +5.8 (c 1, CHCl3);12 Nakagawa’s synthetic 1a , [R]19
D
+2.65 (c 1, CHCl3)}.17 Mori et al. exhibited the temper-
ature dependence of the specific rotation value of 1a :
[R]19 +3.6, [R]23 +0.76, [R]28 -1.5, [R]35 -5.5 (c 0.31,
D
D
D
D
CHCl3).19 Accordingly, our value seems appropriate.
V. Un n a tu r a l Typ es of Sym bior a m id es (1b-d ). We
also synthesized three other diastereomers of symbiora-
mide (1b-d ). 1b, 1c, and 1d were prepared as described
above using S-E-10, R-Z-10, and S-Z-10, respectively.
The specific rotation values of 1b, 1c, and 1d were [R]25
D
+17.2 (c 0.502, CHCl3), [R]25 +49.9 (c 0.5, CHCl3), and
D
[R]25 +63.3 (c 0.5, CHCl3), respectively.
D
The obtained yields of three diastereomers 1b, 1c and
1d based on the corresponding acids were 36, 45, and
41%, respectively. 1c and 1d are newly synthesized
compounds.
VI. An tileu k em ic Activity of Sym bior a m id e De-
r iva tives a ga in st L-1210 a n d HL-60 Cells. To study
the influence of the different structures of the acid parts,
the cell death activity of the natural-type symbioramide
1a was compared with that of three unnatural-type
derivatives 1b-d by MTT assay. Two leukemia cell lines
(HL-60 cells and L-1210 cells) were treated with 10 µM
of a symbioramide derivative for 6 h. C2-Ceramide (N-
acetyl-D-erythro-sphingosine, C2-Cer ) and C2-dihydroce-
ramide (N-acetyl-D-erythro-dihydrosphingosine, C2-DH-
Cer ) were used as positive and negative controls,
respectively. None of the four symbioramide derivatives
showed antileukemic activities in HL-60 cells (data not
shown). In L-1210 cells, however, all symbioramide
a
Conditions: (a) DCC, HOBt, CH2Cl2, rt. (b) TsOH, CH2Cl2-
MeOH (1:1), rt. (c) BF3-Et2O, EtSH, rt.
equivalent pyridinium p-toluenesulfonate monohydrate
in benzene at reflux for 4 h gave acetonide 19 in 72%
yield as a waxy solid: [R]25 +31.5 (c 2, CHCl3) {lit.17
D
[R]22 +29.5 (c 1.178, CHCl3), as a brown oil; lit.19 [R]21
D
D
+32.4 (c 1.08, CHCl3), as a waxy solid}.
J . Org. Chem, Vol. 68, No. 7, 2003 2793

Azuma et al.
brine and extracted with CH2Cl2. The organic layer was dried
with Na2SO4 and concentrated to give a crude product.
Purification by column chromatography with n-hexane-EtOAc
(6:1) gave 7 (4.52 g, 84%) as a colorless oil: [R]25D -4.4 (c 2.859,
CHCl3); IR (NaCl) 2954, 2889, 1736, 1474, 1256, 1111, 1040,
derivatives showed moderate antileukemic activities
(Figure 1). Compound 1d was the most effective among
the symbioramide derivatives, and the antileukemic
activity is in the order C2-Cer > 1d > 1b > 1c > 1a >
C2-DHCer . It is interesting that unnatural types of (2′S)-
isomers of acid parts, 1d and 1b, are more active than
those of (2′R)-isomers, 1c and 1a .
920, 837, 779 cm-1 1H NMR (400 MHz, CDCl3) δ 0.07 (s, 6
;
H), 0.88 (s, 9 H), 3.43 (s, 3 H), 3.93 (d, 2 H, J ) 4.9 Hz), 4.04
(dt, 1 H, J ) 1, 4.9 Hz), 4.78 (dd, 2 H, J ) 6.8, 13.7 Hz), 9.72
(s, 1 H); HRMS (FAB, direct) calcd for C12H26O5Si, [M + H]+
249.1522; found, 249.1521 (25%).
Con clu sion
(2R,3Z)-1-(ter t-Bu t yld im et h ylsiloxy)-2-(m et h oxym e-
th oxy)-3-octa d ecen e (R-Z-8). To a solution of pentadecylt-
riphenylphosphonium bromide (4.15 g, 7.5 mmol) in dry THF
(10 mL) was added n-BuLi (1.6 M solution in hexane, 4.78 mL)
slowly over 10 min at 0 °C. The resulting dark red solution
was added dropwise to a solution of aldehyde 7 (1.69 g, 6.8
mmol) in dry THF (50 mL) at -78 °C and stirred for 1 h. After
stirring overnight at room temperature, the mixture was
poured into ice-cooled 1 M HCl and extracted with EtOAc.
After drying with Na2SO4, the solvent was concentrated, and
cold ether (100 mL) was added to deposit the resulting
triphenylphosphine oxide. After the precipitate was separated
and the solvent was removed, the residue was purified by
column chromatography with n-hexane-AcOEt (20:1) to give
R-Z-8 (1.75 g, 58%) as a colorless oil. The (E)-isomer was not
Naturally occurring symbioramide 1a and its three
diastereomers (1b-d ) having different acid part struc-
tures were synthesized. The proposed methods of prepar-
ing the (E)- and (Z)-isomers are useful because R-hydroxy-
â,γ-unsaturated fatty acid-containing symbioramide is
seldom found in natural sources.
All symbioramide derivatives showed antileukemic
activity against L-1210 cells, although these activities
were less than that of C2-Cer , which is known to induce
apoptosis in various cell types.23 Dihydroceramides are
considered to be physiologically inactive. In fact, C2-Cer
showed strong activity but C2-DHCer showed no cell
death (Figure 1). Nevertheless, dihydroceramide-types
1a -d had antileukemic activity against L-1210 cells. It
is possible that no activities of these derivatives against
HL-60 cells resulted from low cell-permeability. In the
future, we intend to prepare symbioramide analogues
having short-chain acid parts (a chain length less than
eight carbon atoms) to enhance the cell-permeability.
found (by 1H NMR analysis): [R]25 -46.3 (c 3.443, CHCl3);
D
IR (NaCl) 2926, 2855, 1473, 1256, 1213, 1126, 1101, 1034, 920,
837, 777 cm-1; 1H NMR (400 MHz, CDCl3) δ 0.07 (s, 6 H), 0.88
(t, 3 H, J ) 6.8 Hz), 0.90 (s, 9 H), 1.25 (brs, 24 H), 2.10 (q, 2
H, J ) 7.3 Hz), 3.37 (s, 3 H), 3.57 (dd, 1 H, J ) 4.4, 10.7 Hz),
3.68 (dd, 1 H, J ) 7.3, 10.7 Hz), 4.43-4.49 (m, 1 H), 4.59 (d,
1 H, J ) 6.8 Hz), 4.68 (d, 1 H, J ) 6.3 Hz), 5.21 (dd, 1 H, J )
9.5, 11.2 Hz), 5.65 (dt, 1 H, J ) 11.2, 7.3 Hz); HRMS (FAB,
direct) calcd for
441.3744 (30%).
C
26H53O3Si, [M - H]+ 441.3764; found,
Exp er im en ta l Section
(2R,3Z)-2-(Meth oxym eth oxy)-3-octa d ecen -1-ol (R-Z-9).
To a solution of R-Z-8 (2 g, 4.52 mmol) in dry THF (10 mL)
was added tetrabutylammonium fluoride (1 M solution in THF,
6 mL) dropwise at 0 °C, and the solution was stirred at room
temperature for 1 h. The solution was subsequently poured
into water and extracted with diethyl ether. The ether layer
was washed with brine and dried with Na2SO4. The solvent
was concentrated, and the residue was purified by column
chromatography with n-hexane-EtOAc (3:1) to give R-Z-9
All materials were obtained commercially (guaranteed
reagent grade) and used without further purification. All
solvents were freshly distilled under nitrogen before use. THF
and diethyl ether were distilled from LiAlH4; CH2Cl2 and
benzene were distilled from P2O5. Column chromatography
was performed on silica gel.
Met h yl (S)-3-(ter t-Bu t yld im et h ylsiloxy)-2-(m et h oxy-
m eth oxy)p r op ion a te (6). 521 (7.03 g, 30 mmol) and N,N-
diisopropylethylamine (19.4 g, 150 mmol) were dissolved in
dry CH2Cl2 (150 mL). The solution was stirred at room
temperature, and then chloromethyl methyl ether (MOMCl)
(9.66 g, 120 mmol) was added dropwise, and the solution was
stirred for 2 h. The mixture was subsequently poured into
water, and the organic layer was separated and washed with
water, dried with Na2SO4, and concentrated in vacuo. The
residue was purified by column chromatography with chloro-
(1.29 g, 87%) as a colorless oil: [R]25 -60.6 (c 1.46, CHCl3);
D
IR (NaCl) 3447, 2922, 2853, 1466, 1209, 1151, 1101, 1039, 920,
1
721 cm-1; H NMR (400 MHz, CDCl3) δ 0.88 (t, 3 H, J ) 6.8
Hz), 1.26 (brs, 24 H), 2.05-2.14 (m, 2 H), 2.44 (dd, 1 H, J )
4.9, 7.8 Hz), 3.41 (s, 3 H), 3.53-3.60 (m, 2 H), 4.46-4.52 (m,
1 H), 4.60 (d, 1 H, J ) 6.3 Hz), 4.73 (d, 1 H, J ) 6.8 Hz), 5.25
(dd, 1 H, J ) 9.0, 10.7 Hz), 5.67 (dt, 1 H, J ) 10.7, 7.6 Hz);
HRMS (FAB, direct) calcd for C20H40O3Na, [M + Na]+ 351.2875;
found, 351.2867 (52%).
form to give 6 as a colorless oil (6.91 g, 84%): [R]25 -26.0 (c
D
2.37, CHCl3); IR (NaCl) 2955, 2858, 1755, 1463, 1437, 1362,
(2R,3E)-2-(Meth oxym eth oxy)-3-octa d ecen -1-ol (R-E-9).
A solution of R-Z-9 (720 mg, 2.19 mmol) and diphenyl disulfide
(158 mg, 0.72 mmol) in dry cyclohexane-dioxane (3:1, 20 mL)
in a Pyrex test tube (25 mL) was degassed under N2. The
solution was irradiated by a water-cooled high-pressure mer-
cury lamp for 1 h. The slightly yellow solution was treated
twice with diphenyl disulfide (2 × 158 mg, 2 × 0.72 mmol)
and irradiated over a total period of 3 h. The reaction mixture
was then concentrated to give the residue containing the (E)-
1258, 1205, 1155, 1126, 1047, 922, 839, 779 cm-1 1H NMR
;
(400 MHz, CDCl3) δ 0.06 (s, 6 H), 0.88 (s, 9 H), 3.40 (s, 3 H),
3.75 (s, 3 H), 3.91 (d, 2 H, J ) 4.9 Hz), 4.25 (t, 1 H, J ) 4.9
Hz), 4.73 (s, 2 H); HRMS (FAB, direct) calcd for C12H26O5Si,
[M + H]+ 279.1628; found, 279.1624 (22%). Anal. Calcd: C,
51.77; H, 9.41. Found: C, 51.64; H, 9.64.
Met h yl (S)-3-(ter t-Bu t yld im et h ylsiloxy)-2-(m et h oxy-
m eth oxy)p r op a n a l (7). To a solution of 6 (6.0 g, 21.6 mmol)
in dry toluene (100 mL) at -78 °C was added DIBAL in toluene
(1.5 M, 21.6 mL). The reaction mixture was stirred for 1 h at
-78 °C, and then methanol (30 mL) and saturated phosphorus
buffer (pH 7.0, 200 mL) were added. After the reaction mixture
had been stirred for 30 min, the mixture was treated with
1
and (Z)-olefins 9 in a 74:26 ratio (by H NMR analysis). The
residue was purified by column chromatography with n-hex-
ane-EtOAc (3:1) and recrystallized from n-hexane to give
R-E-9 (370 mg, 51%) as a powdery solid: mp 44 °C (lit.19 mp
39-40 °C); [R]25 -80.4 (c 1.24, CHCl3) {lit.19 [R]23 -77.5 (c
D
D
0.9, CHCl3)}; IR (KBr) 3320, 2918, 2851, 1468, 1152, 1098,
(23) (a) Ito, A.; Uehara, T.; Tokumitsu, A.; Okuma, Y.; Nomura, Y.
Biochim. Biophys. Acta 1999, 1452, 263. (b) Monti, B.; Zanghellini, P.;
Contestabile, A. Neurochem. Int. 2001, 39, 11. (c) Itakura, A.; Tanaka,
A.; Aioi, A.; Tonogaito, H.; Matsuda, H. Exp. Hematology 2002, 30,
272.
1
1036, 966, 914, 721 cm-1; H NMR (400 MHz, CDCl3) δ 0.88
(t, 3 H, J ) 6.8 Hz), 1.25 (brs, 22 H), 1.34-1.41 (m, 2 H), 2.05
(q, 2 H, J ) 6.8 Hz), 2.37 (t, 3 H, J ) 6.83 Hz), 3.40 (s, 3 H),
3.56-3.60 (m, 2 H), 4.10 (dt, 1 H, J ) 4.9, 6.8 Hz), 4.61 (d, 1
2794 J . Org. Chem., Vol. 68, No. 7, 2003

Total Syntheses of Symbioramide Derivatives
H, J ) 6.8 Hz), 4.75 (d, 1 H, J ) 6.8 Hz), 5.31 (dd, 1 H, J )
7.8, 15.6 Hz), 5.76 (dt, 1 H, J ) 15.6, 6.8 Hz); MS (FAB, direct)
calcd for C20H40O3Na, [M + Na]+ 351.3; found, 351.4 (24%).
(1.74 g, 81%) as a colorless oil: [R]25 +10.9 (c 1.451, CHCl3)
D
{lit.19 [R]23D -11.4 (c 1.33, CHCl3)}; IR (NaCl) 2936, 2855, 1464,
1254, 1111, 968, 837, 777 cm-1; 1H NMR (400 MHz, CDCl3) δ
0.08 (s, 6 H), 0.89 (t, 3 H, J ) 7.2 Hz), 0.91 (s, 9 H), 1.26 (brs,
22 H), 1.34-1.42 (m, 2 H), 2.03 (q, 2 H, J ) 6.8 Hz), 2.57 (d,
1 H, J ) 2.8 Hz), 3.42 (dd, 1 H, J ) 8.4, 10 Hz), 3.62 (dd, 1 H,
J ) 3.6, 10 Hz), 4.08-4.18 (m, 1 H), 5.39 (dd, 1 H, J ) 3, 15.6
Hz), 5.76 (dt, 1 H, J ) 15.6, 6.8 Hz); HRMS (FAB, direct) calcd
for C24H49O2Si, [M - H]+ 397.3502; found, 397.3492 (100%).
(2R,3E)-2-(Meth oxym eth oxy)-3-octa d ecen oic Acid (R-
E-10). A mixture of R-E-9 (400 mg, 1.22 mmol) and PDC (2.74
g, 7.27 mmol) in N,N-dimethylformamide (DMF, 8 mL) was
stirred for 3 h at 40-50 °C under N2.The resulting mixture
was diluted with water and extracted with ethyl acetate. The
extract was washed with saturated brine, dried with Na2SO4,
and concentrated to give the crude acid as a brown oil. The
residue was purified by column chromatography with n-hex-
ane-EtOAc (1:1) to give R-E-10 (330 mg, 78%) as a solid. Since
the MOM group of R-E-10 could be easily decomposed, this
acid was used immediately in the next step: mp 57-58 °C;
[R]25D -64.5 (c 0.882, CHCl3); IR (KBr) 2918, 2851, 1736, 1464,
(2S,3Z)-1-(ter t-Bu tyld im eth ylsiloxy)-3-octa d ecen -2-ol
(S-Z-14). The reaction was carried out as described above,
using S-Z-1322 (500 mg, 1.76 mmol) to give S-Z-14 (500 mg,
71%) as a colorless oil: [R]25D +25.2 (c 1.608, CHCl3); IR (NaCl)
3463, 2955, 2855, 1464, 1312, 1256, 1107, 1069, 968, 837, 779,
1
721 cm-1; H NMR (400 MHz, CDCl3) δ 0.09 (s, 6 H), 0.88 (t,
1202, 1111, 1026, 970, 897, 719 cm-1 1H NMR (400 MHz,
;
3 H, J ) 6.8 Hz), 0.92 (s, 9 H), 1.26 (brs, 24 H), 2.02-2.15 (m,
2 H), 2.54 (d, 1 H, J ) 2.4 Hz), 3.41 (dd, 1 H, J ) 8.4, 10 Hz),
3.57 (dd, 1 H, J ) 3.6, 10 Hz), 4.43-4.50 (m, 1 H), 5.32 (dd,1
H, J ) 8.5, 11.2 Hz), 5.57 (dt, 1 H, J ) 11.2, 6.4 Hz); HRMS
(FAB, direct) calcd for C24H49O2Si [M - H]+ 397.3502; found,
397.3496 (100%).
CDCl3) δ 0.88 (t, 3 H, J ) 6.8 Hz), 1.25 (brs, 22 H), 1.36-1.42
(m, 2 H), 2.09 (q, 2 H, J ) 6.8 Hz), 3.41 (s, 1 H), 4.64 (d, 1 H,
J ) 7.3 Hz), 4.69 (d, 1 H, J ) 6.8 Hz), 4.77 (d, 1 H, J ) 6.8
Hz), 5.47 (dd, 1 H, J ) 7.3, 15.6 Hz), 5.94 (dt, 1 H, J ) 15.6,
6.8 Hz); HRMS (FAB, direct) calcd for C20H37O4, [M - H]+
341.2692; found, 341.2690 (100%).
(2S,3E)-2-(Meth oxym eth oxy)-3-octa d ecen -1-ol (S-E-9).
To a solution of S-E-14 (1.74 g, 4.36 mmol) and N,N-diisopro-
pylethylamine (2.32 g, 18 mmol) in dry CH2Cl2 (50 mL) was
added MOMCl (1.74 g, 21.6 mmol) dropwise at 0 °C. The
reaction mixture was stirred for 2 h at room temperature. The
mixture was subsequently poured into water, and the organic
layer was separated and washed with brine, dried with Na2-
SO4, and concentrated in vacuo. The residue was dissolved in
THF (50 mL), and the solution was stirred in an ice bath. Then,
tetrabutylammonium fluoride (1 M solution in THF, 5.8 mL)
was added dropwise at 0 °C, and the mixture was stirred at
room temperature for 1 h. The mixture was subsequently
poured into water and extracted with diethyl ether. The ether
layer was washed with brine, dried with Na2SO4, and concen-
trated in vacuo. The residue was purified by column chroma-
tography with n-hexane-EtOAc (3:1) and recrystallized from
n-hexane to give S-E-9 (1.15 g, 80%) as a powdery solid; mp
(2R,3Z)-2-(Meth oxym eth oxy)-3-octa d ecen oic Acid (R-
Z-10). The reaction was carried out as described above, using
R-Z-9 (400 mg, 1.22 mmol) to give R-Z-10 (290 mg, 69%) as a
colorless oil: [R]25 -116.1 (c 1.764, CHCl3); IR (NaCl) 2910,
D
2890, 1729, 1466, 1215, 1151, 1107, 1040, 920, 768, 721 cm-1
;
1H NMR (400 MHz, CDCl3) δ 0.88 (t, 3 H, J ) 6.8 Hz), 1.26
(brs, 22 H), 1.36-1.42 (m, 2 H), 2.05 (s, 1 H), 2.19 (q, 1 H, J )
7.3 Hz), 3.41 (s, 1 H), 4.12 (q, 1 H, J ) 7.3 Hz), 4.67 (d, 1 H,
J ) 6.8 Hz), 4.74 (d, 1 H, J ) 6.8 Hz), 5.05 (d, 1 H, J ) 9.3
Hz), 5.39 (dd, 1 H, J ) 9.3, 10.7 Hz), 5.85 (dt, 1 H, J ) 10.7,
7.3 Hz); HRMS (FAB, direct) calcd for C20H37O4, [M - H]+
341.2692; found, 341.2689 (100%).
(2S,3E)-3-Octadecen -1,2-diol (S-E-13). A solution of Z-1222
(4.58 g, 14.1 mmol) and diphenyl disulfide (340 mg, 1.55 mmol)
in dry cyclohexane-dioxane (3:1, 100 mL) in a Pyrex flask (100
mL) was degassed under N2. The solution was irradiated by a
water-cooled high-pressure mercury lamp for 1 h. The slightly
yellow solution was treated twice with diphenyl disulfide (2
× 340 mg, 2 × 1.55 mmol) and irradiated over a total period
of 3 h. The reaction mixture was then concentrated to give
the residue containing the (E)- and (Z)-olefins 13 in a 91:9 ratio
(by 1H NMR analysis). The residue was dissolved in a mixture
of acetic acid (25 mL), water (15 mL), THF (4.5 mL), and 1 M
sulfuric acid (1 mL) and stirred for 24 h at room temperature.
After neutralization with potassium carbonate and extraction
with ethyl acetate, the organic phase was dried with Na2SO4
and concentrated. The residue was purified by column chro-
matography with chloroform-methanol (10:1) and recrystal-
lized from n-hexane to give S-E-13 (2.77 g, 69%) as a solid:
44 °C; [R]25 +80.9 (c 1.01, CHCl3); MS (FAB, direct) calcd for
D
C
20H40O3Na, [M + Na]+ 351.3; found 351.4 (5%).
(2S,3Z)-2-(Meth oxym eth oxy)-3-octa d ecen -1-ol (S-Z-9).
The reaction was carried out as described above, using S-Z-
14 (800 mg, 2.01 mmol) to give S-Z-9 (500 mg, 76%) as a
colorless oil: [R]25D +59.6 (c 1.74, CHCl3); HRMS (FAB, direct)
calcd for C20H40O3Na [M + Na]+ 351.2875; found 351.2870
(28%).
(2S,3E)-2-(Meth oxym eth oxy)-3-octa d ecen oic Acid (S-
E-10). The reaction was carried out as described above, using
S-E-9 (400 mg, 1.22 mmol) to give S-E-10 (330 mg, 79%) as a
solid: mp 56-57 °C; [R]25D +64.8 (c 2.09, CHCl3); HRMS (FAB,
direct) calcd for C20H37O4, [M - H]+ 341.2692; found, 341.2673
(100%).
(2S,3Z)-2-(Meth oxym eth oxy)-3-octa d ecen oic Acid (S-
Z-10). The reaction was carried out as described above, using
S-Z-9 (300 mg, 0.91 mmol) to give S-Z-10 (260 mg, 83%) as a
colorless oil; [R]25D +111.1 (c 1.36, CHCl3); HRMS (FAB, direct)
calcd for C20H37O4, [M - H]+ 341.2692; found 341.2681 (100%).
mp 60.5-61.5 °C (lit.17 mp 60-60.5 °C); [R]25 +9.07 (c 1.534,
D
CHCl3) {lit.17 [R]29 +9.05 (c 0.398, CHCl3)}; IR (KBr) 3342,
D
2920, 2849, 1470, 1082, 1022, 976, 719 cm-1
;
1H NMR (400
MHz, CDCl3); δ 0.88 (t, 3 H, J ) 6.8 Hz), 1.26 (brs, 22 H),
1.34-1.42 (m, 2 H), 2.02 (q, 2 H, J ) 6.8 Hz), 2.10 (brs, 1 H),
2.19 (brs, 1 H), 3.49 (dd, 1 H, J ) 7.8, 10.7 Hz), 3.63 (d, 1 H,
J ) 11.2 Hz), 4.19 (m, 1 H), 5.44 (dd,1 H, J ) 6.8, 15.6 Hz),
5.78 (dt, 1 H, J ) 15.6, 6.8 Hz); MS (EI, direct) calcd for
1,3-Isop r op ylid en e-D-er yth r o-d ih yd r osp h in gosin e (19).
A solution of 215 (1.12 g, 3.71 mmol), pyridinium p-toluene-
sulfonate (0.94 g, 3.72 mmol), and 2,2-dimethoxypropane (9
mL) in dry benzene (20 mL) was heated under reflux for 4 h.
The mixture was cooled and washed with a saturated NaHCO3
solution. The organic layer was dried with Na2SO4 and
concentrated. The residue was purified by column chromatog-
raphy with chloroform-methanol (40:1) and crystallized with
n-hexane to give 19 (910 mg, 72%) as a waxy solid: mp 36-
C
18H35O2, [M]+ 284; found, 284 (0.4%), [M - CH2OH]+ 253;
found, 253 (87%).
(2S,3E)-1-(ter t-Bu tyld im eth ylsiloxy)-3-octa d ecen -2-ol
(S-E-14). To a solution of S-E-13 (1.54 g, 5.41 mmol), triethy-
lamine (0.66 g, 6.49 mmol), and 4-(dimethylamino)pyridine (27
mg, 0.22 mmol) in dry CH2Cl2 (50 mL) was added a solution
of tert-butylchlorodimethylsilane (0.9 g, 6 mmol) in dry CH2-
Cl2 (10 mL) at 0 °C. The reaction mixture was stirred overnight
at room temperature, and then phosphate buffer (pH 7.0) was
added. The mixture was extracted with diethyl ether, and the
organic layer was washed with brine and dried with Na2SO4.
After concentration of the solvent, the residue was purified
by column chromatography with chloroform to give S-E-14
37 °C (lit.17 brown oil and lit.19 mp 61-62 °C); [R]25 +31.7 (c
D
1.03, CHCl3) {lit.17 [R]22D +29.5 (c 1.178, CHCl3) and lit.19 [R]21
D
+32.4 (c 1.08, CHCl3); IR (KBr) 2914, 2851, 1468, 1375, 1202,
1
1167, 891, 719 cm-1; H NMR (400 MHz, CDCl3) δ 0.88 (t, 3
H, J ) 6.8 Hz), 1.01 (brs, 2 H), 1.26 (brs, 26 H), 1.39 (s, 3 H),
1.44 (s, 3 H), 1.45-1.55 (m, 1 H), 1.68-1.78 (m, 1 H), 2.64 (dt,
J . Org. Chem, Vol. 68, No. 7, 2003 2795

Azuma et al.
1 H, J ) 4.9, 9.5 Hz), 3.40 (dt, 1 H, J ) 2, 9 Hz), 3.45 (dd, 1 H,
J ) 11.2, 9.8 Hz), 3.81 (dd, 1 H, J ) 11.2, 5.4 Hz); MS (FAB,
direct) calcd for C21H43NO2, [M + H]+ 342.3; found 342.5 (73%).
of R-E-20 (510 mg, 0.763 mmol) and p-toluenesulfonic acid (20
mg) in CH2Cl2 (10 mL) was stirred for 1 h at room temperature.
The reaction mixture was washed with saturated NaHCO3,
dried with Na2SO4, and concentrated in vacuo. The residue
was purified by column chromatography with CH2Cl2-MeOH
(40:1) to give R-E-21 (380 mg, 79%) as a solid: mp 100-104
°C; [R]25 -24.2 (c 0.84, CHCl3) {lit.17 [R]23 -27.1 (c 0.981,
(2S ,3R ,2′R ,3′E )-2-N -(2′-Me t h oxym e t h oxy-3′-oct a d e -
cen oyl)-1,3-O-isop r op ylid en -[2-a m in o-octa d eca n -1,3-d i-
ol] (R-E-20). To a suspension of acid R-E-10 (169 mg, 0.49
mmol), DCC (104 mg, 0.49 mmol), and HOBt (67 mg, 0.49
mmol) in dry CH2Cl2 (10 mL) was added dropwise a solution
of primary amine 19 (167 mg, 0.49 mmol) in dry CH2Cl2 (2
mL), and the mixture was stirred overnight at room temper-
ature. The resulting suspension was filtered and concentrated.
The obtained residue was purified by column chromatography
with n-hexane-EtOAc (3:1) to give R-E-20 (260 mg, 79%) as
D
D
CHCl3)}; IR (KBr) 3289, 2918, 2849, 1653, 1541, 1466, 1155,
1
1072, 1036, 982, 918, 719 cm-1; H NMR (400 MHz, CDCl3,
50 °C) δ 0.88 (t, 6 H, J ) 6.8 Hz), 1.25 (brs, 48 H), 1.35-1.41
(m, 2 H), 1.45-1.58 (m, 2 H), 2.07 (q, 2 H, J ) 7.3 Hz), 2.71
(d, 1 H, J ) 5.9 Hz), 2.91 (brs, 1 H), 3.40 (s, 3 H), 3.79 (m, 3
H), 4.02 (d, 1 H, J ) 11.7 Hz), 4.50 (d, 1 H, J ) 7.3 Hz), 4.67
(d, 1 H, J ) 6.8 Hz), 4.75 (d, 1 H, J ) 6.8 Hz), 5.42 (dd, 1 H,
J ) 7.3, 15.1 Hz), 5.88 (dt, 1 H, J ) 15.1, 6.8 Hz), 7.38 (d, 1 H,
J ) 7.8 Hz); HRMS (FAB, direct) calcd for C38H75NO5, [M +
H]+ 626.5723; found, 626.5724 (53%).
a waxy solid: mp 58-60 °C; [R]25 -16.7 (c 2.07, CHCl3); IR
D
(KBr) 3320, 2920, 2849, 1647, 1520, 1464, 1375, 1205, 1153,-
1024, 986, 920, 719 cm-1; 1H NMR (400 MHz, CDCl3, 50 °C) δ
0.88 (t, 6 H, J ) 6.8 Hz), 1.25 (brs, 50 H), 1.39 (s, 3 H), 1.45 (s,
3 H), 1.37-1.54 (m, 2 H), 2.07 (q, 2 H, J ) 6.8 Hz), 3.38 (s, 3
H), 3.54-3.62 (m, 2 H), 3.85-3.94 (m, 2 H), 4.48 (d, 1 H, J )
7.3 Hz), 4.62 (d, 1 H, J ) 6.3 Hz), 4.74 (d, 1 H, J ) 6.3 Hz),
5.36 (dd, 1 H, J ) 7.3, 15.6 Hz), 5.86 (dt, 1 H, J ) 15.6, 6.8
(2S ,3R ,2′S ,3′E )-2-N -(2′-Me t h oxym e t h oxy-3′-oct a d e -
cen oyl)-[2-a m in o-octa d eca n -1,3-d iol] (S-E-21). The reac-
tion was carried out as described above, using S-E-20 (240 mg,
0.359 mmol) to give S-E-21 (180 mg, 80%) as a solid: mp 97-
98 °C; [R]25D +37.8 (c 0.943, CHCl3); IR (KBr) 3240, 2918, 2851,
Hz), 6.44 (d, 1 H, J ) 9.3 Hz); MS (FAB, direct) calcd for C41H80
-
NO5, [M + H]+ 666.60; found, 666.75 (17%).
1661, 1553, 1470, 1153, 1109, 1043, 974, 918, 719 cm-1 1H
;
NMR (400 MHz, CDCl3, 50 °C) δ 0.88 (t, 6 H, J ) 6.8 Hz),
1.25 (brs, 48 H), 1.36-1.42 (m, 2 H), 1.51-1.59 (m, 2 H), 2.07
(q, 2 H, J ) 7.3 Hz), 2.56 (d, 1 H, J ) 5.9 Hz), 2.60 (brs, 1 H),
3.39 (s, 3 H), 3.73-3.84 (m, 3 H), 4.02 (d, 1 H, J ) 11.7 Hz),
4.49 (d, 1 H, J ) 7.3 Hz), 4.66 (d, 1 H, J ) 6.8 Hz), 4.73 (d, 1
H, J ) 6.3 Hz), 5.44 (dd, 1 H, J ) 7.3, 15.1 Hz), 5.87 (dt, 1 H,
J ) 15.1, 6.8 Hz), 7.27 (d, 1 H, J ) 7.8 Hz); HRMS (FAB, direct)
calcd for C38H75NO5, [M + H]+ 626.5723; found, 626.5717
(76%).
(2S ,3R ,2′S ,3′E )-2-N -(2′-Me t h oxym e t h oxy-3′-oct a d e -
cen oyl)-1,3-O-isop r op ylid en -[2-a m in o-octa d eca n -1,3-d i-
ol] (S-E-20). The reaction was carried out as described above,
using S-E-10 (360 mg, 1.05 mmol) to give S-E-20 (440 mg,
63%) as a waxy solid: mp 51-52 °C; [R]25 -50.3 (c 1.114,
D
CHCl3); IR (KBr) 3280, 2916, 2849, 1651, 38 1468, 1379, 1202,
1153,1083, 1030, 966, 918, 721 cm-1 1H NMR (400 MHz,
;
CDCl3, 50 °C) δ 0.88 (t, 6 H, J ) 6.8 Hz), 1.26 (brs, 50 H), 1.38
(s, 3 H), 1.43 (s, 3 H), 1.35-1.58 (m, 2 H), 2.07 (q, 2 H, J ) 7.3
Hz), 3.37 (s, 3 H), 3.54 (dd, 1 H, J ) 7.8, 11.2 Hz), 3.60 (dd, 1
H, J ) 3.4, 8.3 Hz), 3.78-3.88 (m, 1 H), 3.90 (dd, 1 H, J ) 5.4,
11.2 Hz), 4.45 (d, 1 H, J ) 7.3 Hz), 4.61 (d, 1 H, J ) 6.8 Hz),
4.71 (d, 1 H, J ) 6.4 Hz), 5.37 (dd, 1 H, J ) 7.1, 15.6 Hz), 5.84
(dt, 1 H, J ) 15.6, 7.8 Hz), 6.41 (d, 1 H, J ) 9.3 Hz); HRMS
(FAB, direct) calcd for C41H79NO5, [M]+ 665.5958; found,
665.5962 (2.6%).
(2S ,3R ,2′R ,3′Z)-2-N -(2′-Me t h oxym e t h oxy-3′-oct a d e -
cen oyl)-1,3-O-isop r op ylid en -[2-a m in o-octa d eca n -1,3-d i-
ol] (R-Z-20). The reaction was carried out as described above,
using R-Z-10 (270 mg, 0.784 mmol) to give R-Z-20 (380 mg,
73%) as a colorless oil; [R]25D -54.5 (c 0.618, CHCl3); IR (NaCl)
3323, 2916, 2849, 1647, 1529, 1468, 1375, 1207, 1157,1105,
1051, 976, 922, 721 cm-1; 1H NMR (400 MHz, CDCl3, 50 °C) δ
0.88 (t, 6 H, J ) 6.8 Hz), 1.25 (brs, 50 H), 1.37-1.54 (m, 2 H),
1.39 (s, 3 H), 1.45 (s, 3 H), 2.21 (q, 2 H, J ) 7.3 Hz), 3.37 (s, 3
H), 3.58 (dd, 1 H, J ) 7.3, 11.2 Hz), 3.57-3.62 (m, 1 H), 3.84-
3.96 (m, 2 H), 4.59 (d, 1 H, J ) 6.8 Hz), 4.71 (d, 1 H, J ) 6.4
Hz), 4.87 (d, 1 H, J ) 9.3 Hz), 5.19 (dd, 1 H, J ) 9.3, 10.7 Hz),
5.85 (dt, 1 H, J ) 10.7, 7.3 Hz), 6.49 (d, 1 H, J ) 9.3 Hz);
HRMS (FAB, direct) calcd for C41H80NO5, [M + H]+ 666.6036;
found, 666.6059 (84%).
(2S ,3R ,2′R ,3′Z)-2-N -(2′-Me t h oxym e t h oxy-3′-oct a d e -
cen oyl)-[2-a m in o-octa d eca n -1,3-d iol] (R-Z-21). The reac-
tion was carried out as described above, using R-Z-20 (350
mg, 0.524 mmol) to give R-Z-21 (280 mg, 85%) as a solid: mp
62-63 °C; [R]25 -73.2 (c 0.22, CHCl3); IR (KBr) 3289, 2918,
D
2851, 1655, 1539, 1470, 1153, 1049, 980, 918, 719 cm-1
;
1H
NMR (400 MHz, CDCl3, 50 °C) δ 0.88 (t, 6 H, J ) 6.8 Hz),
1.25 (brs, 48 H), 1.38-1.48 (m, 2 H), 1.48-1.58 (m, 2 H), 2.22
(q, 2 H, J ) 7.3 Hz), 2.44 (d, 1 H, J ) 5.4 Hz), 2.58 (brs, 1 H),
3.39 (s, 3 H), 3.76-3.82 (m, 3 H), 4.01 (d, 1 H, J ) 11.7 Hz),
4.64 (d, 1 H, J ) 6.3 Hz), 4.71 (d, 1 H, J ) 6.3 Hz), 4.88 (d, 1
H, J ) 9.3 Hz), 5.29 (dd, 1 H, J ) 9.0, 10.7 Hz), 5.82 (dt, 1 H,
J ) 10.7, 7.3 Hz), 7.29 (d, 1 H, J ) 6.4 Hz); MS (FAB, direct)
calcd for C38H75NO5, [M + H]+ 626.6; found, 626.7 (35%).
(2S ,3R ,2′S ,3′Z)-2-N -(2′-Me t h oxym e t h oxy-3′-oct a d e -
cen oyl)-[2-a m in o-octa d eca n -1,3-d iol] (S-Z-21). The reac-
tion was carried out as described above, using S-Z-20 (300 mg,
0.449 mmol) to give S-Z-21 (210 mg, 74%) as a solid; mp 70.5-
72.5 °C; [R]25D -71.3 (c 1.1, CHCl3); IR (KBr) 3280, 2918, 2849,
1655, 1553, 1468, 1239, 1153, 1101, 1057, 980, 949, 907, 799,
1
721 cm-1; H NMR (400 MHz, CDCl3, 50 °C) δ 0.88 (t, 6 H, J
) 6.8 Hz), 1.25 (brs, 50 H), 1.47-1.58 (m, 2 H), 2.22 (q, 2 H,
J ) 6.8 Hz), 2.55 (d, 1 H, J ) 5.9 Hz), 2.61 (brs, 1 H), 3.39 (s,
3 H), 3.72-3.84 (m, 3 H), 4.01 (d, 1 H, J ) 11.2 Hz), 4.63 (d,
1 H, J ) 6.8 Hz), 4.71 (d, 1 H, J ) 6.3 Hz), 4.88 (d, 1 H, J )
9.3 Hz), 5.29 (dd, 1 H, J ) 8.9, 10.7 Hz), 5.82 (dt, 1 H, J )
10.7, 7.3 Hz), 7.29 (d, 1 H, J ) 6.8 Hz); HRMS (FAB, direct)
calcd for C38H75NO5, [M + H]+ 626.5723; found, 626.5714
(100%).
(2S ,3R ,2′S ,3′Z)-2-N -(2′-Me t h oxym e t h oxy-3′-oct a d e -
cen oyl)-1,3-O-isop r op ylid en -[2-a m in o-octa d eca n -1,3-d i-
ol] (S-Z-20). The reaction was carried out as described above,
using S-Z-9 (250 mg, 0.73 mmol) to give S-Z-20 (330 mg, 68%)
as a waxy solid: mp 44-45 °C; [R]25 +81.5 (c 1.525, CHCl3);
D
IR (KBr) 3422, 2920, 2853, 1680, 1506, 1472, 1387, 1159, 1109,
1057, 920, 799, 718 cm-1; 1H NMR (400 MHz, CDCl3, 50 °C) δ
0.88 (t, 6 H, J ) 6.8 Hz), 1.26 (brs, 50 H), 1.38 (s, 3 H), 1.43 (s,
3 H), 1.38-1.61 (m, 2 H), 2.21 (q, 2 H, J ) 6.8 Hz), 3.37 (s, 3
H), 3.55 (dd, 1 H, J ) 7.6, 11.2 Hz), 3.60 (dt, 1 H, J ) 3.4, 8.3
Hz), 3.78-3.87 (m, 1 H), 3.91 (dd, 1 H, J ) 5.4, 11.2 Hz), 4.59
(d, 1 H, J ) 6.8 Hz), 4.69 (d, 1 H, J ) 6.8 Hz), 4.85 (d, 1 H, J
) 9.3 Hz), 5.21 (dd, 1 H, J ) 9.3, 10.7 Hz), 5.81 (dt, 1 H, J )
10.7, 7.5 Hz), 6.44 (d, 1 H, J ) 8.8 Hz); HRMS (FAB, direct)
calcd for C41H80NO5, [M + H]+ 666.6036; found, 666.6040
(100%).
(2S,3R,2′R,3′E)-2-N-(2′-H yd r oxy-3′-oct a d ecen oyl)-[2-
am in o-octadecan -1,3-diol] (Sym bior am ide, 1a). To a stirred
suspension of R-E-22 (300 mg, 0.449 mmol) in ethanethiol (20
mL) was added a few drops of boron trifluoride-diethyl ether
under N2, and the mixture was stirred for 1 h at room
temperature. The resulting clear solution was poured into
saturated aqueous NaHCO3 and extracted with CHCl3. The
extract was dried with Na2SO4 and concentrated in vacuo. The
residue was purified by column chromatography with CHCl3-
MeOH (20:1) and recrystallized from acetone-benzene to give
1a (180 mg, 69%) as a powdery solid: mp 114-115 °C (lit.11
(2S ,3R ,3′R ,3′E )-2-N -(2′-Me t h oxym e t h oxy-3′-oct a d e -
cen oyl)-[2-a m in o-octa d eca n -1,3-d iol] (R-E-21). A solution
2796 J . Org. Chem., Vol. 68, No. 7, 2003

Total Syntheses of Symbioramide Derivatives
mp 105-107 °C, lit.17 mp 112-113 °C, and lit.19 mp 115-116.5
°C); [R]25 +1.19 (c 0.5, CHCl3) {lit.11 [R]22 +5.8 (c 1, CHCl3),
10.7, 7.8 Hz), 7.25 (d, 1 H, J ) 2 Hz); HRMS (FAB, direct)
calcd for C36H71NO4, [M + H]+ 582.5461; found, 582.5463
(100%). Anal. Calcd: C, 74.30; H, 12.30; N, 2.41. Found: C,
74.28; H, 12.41; N, 2.42.
D
D
lit.17 [R]19D +2.65 (c 0.378, CHCl3), and lit.19 [R]19D +3.6, [R]23
D
+0.76, [R]28D -1.5, [R]35D -5.5 (c 0.31, CHCl3)}; IR (KBr) 3280,
1
2918, 2849, 1651, 1626, 1541, 1468, 1069, 978, 721 cm-1; H
(2S,3R,2′S,3′Z)-2-N -(2′-H yd r oxy-3′-oct a d e ce n oyl)-[2-
a m in o-octa d eca n -1,3-d iol] (1d ). The reaction was carried
out as described above, using S-Z-22 (210 mg, 0.334 mmol) to
NMR (400 MHz, CDCl3, 50 °C) δ 0.88 (t, 6 H, J ) 6.8 Hz),
1.26 (brs, 50 H), 1.38 (m, 1 H), 1.53 (m, 1 H), 2.08 (q, 2 H, J )
7.0 Hz), 2.60 (d, 1 H, J ) 6.4 Hz), 2.77 (brs, 1 H), 3.26 (d, 1 H,
J ) 3.6 Hz), 3.77-3.84 (m, 3 H), 3.99 (d, 1 H, J ) 11.2 Hz),
4.53 (dd, 1 H, J ) 3.4, 6.8 Hz), 5.57 (dd, 1 H, J ) 6.8, 15.4
Hz), 5.89 (dt, 1 H, J ) 14.2, 6.8 Hz), 7.01 (d, 1 H, J ) 7.8 Hz);
HRMS (FAB, direct) calcd for C36H71NO4, [M + H]+ 582.5461;
found, 582.5455 (100%). Anal. Calcd: C, 74.30; H, 12.30; N,
2.41. Found: C, 74.30; H, 12.44; N, 2.35.
give 1d (160 mg, 82%) as a powdery solid; mp 87-88 °C; [R]25
D
+63.3 (c 0.5, CHCl3); IR (KBr) 3290, 2955, 2851, 1663, 1549,
1470, 1259, 1140, 1053, 926, 822, 719 cm-1; 1H NMR (400 MHz,
CDCl3, 50 °C) δ 0.88 (t, 6 H, J ) 6.8 Hz), 1.26 (brs, 50 H),
1.38-1.46 (m, 1 H), 1.48-1.56 (m, 1 H), 2.19-2.26 (m, 2 H),
2.42 (d, 1 H, J ) 4.8 Hz), 2.51 (brs, 1 H), 3.01 (brs, 1 H), 3.72-
3.84 (m, 3 H), 4.01 (d, 1 H, J ) 10.7 Hz), 4.87 (d, 1 H, J ) 8.8
Hz), 5.44 (dd, 1 H, J ) 9.3, 10.7 Hz), 5.77 (dt, 1 H, J ) 10.7,
7.6 Hz), 6.93 (d, 1 H, J ) 7.3 Hz); HRMS (FAB, direct) calcd
for C36H71NO4, [M + H]+ 582.5461; found, 582.5463 (100%).
Anal. Calcd: C, 74.30; H, 12.30; N, 2.41. Found: C, 74.33; H,
12.32; N, 2.40.
(2S,3R,2′S,3′E)-2-N-(2′-H yd r oxy-3′-oct a d e ce n oyl)-[2-
a m in o-octa d eca n -1,3-d iol] (1b). The reaction was carried
out as described above, using S-E-22 (180 mg, 0.287 mmol) to
give 1b (120 mg, 72%) as a powdery solid; mp 104 °C (lit.19
mp 99.5-100.5 °C); [R]25 +17.2 (c 0.502, CHCl3) {lit.19 [R]18
D
D
+42.9, [R]23 +37.2, [R]27 +30.6, [R]39 +27.5, [R]35 +22.3 (c
MTT Assa y. After washing with serum-free RPMI-1640
medium, cells were suspended at 4 × 105/mL with 10 µM of
symbioramide derivatives (stock solution, 10 mM in 98%
EtOH-2% dodecane) and plated in 96 well plates. Cells (4 ×
104/well) were cultured for 6 h. MTT (10 mL of 5 mg/mL) was
added to each well 2 h before the end of the culture, and
reactions were stopped by the addition of 100 µL of 0.04 M
HCl/2-propanol; two optical densities of the mixture were
measured at 570 and 650 nm. Final values were obtained by
subtracting 650 nm from 570 nm lectures.23c
D
D
D
D
0.15, CHCl3)}; IR (KBr) 3320, 2916, 2849, 1649, 1553, 1472,
1074, 1037, 964, 718 cm-1; 1H NMR (400 MHz, CDCl3, 50 °C)
δ 0.88 (t, 6 H, J ) 6.8 Hz), 1.26 (brs, 50 H), 1.38-1.46 (m, 1
H), 1.48-1.56 (m, 1 H), 2.08 (q, 2 H, J ) 7.3 Hz), 2.32 (d, 1 H,
J ) 5.9 Hz), 2.41 (brs, 1 H), 2.95 (d, 1 H, J ) 3.4 Hz), 3.72-
3.85 (m, 3 H), 4.02 (d, 1 H, J ) 11.2 Hz), 4.51 (d, 1 H, J ) 4.4
Hz), 5.56 (dd, 1 H, J ) 7, 15.6 Hz), 5.90 (dt, 1 H, J ) 15.1, 5.9
Hz), 6.89 (d, 1 H, J ) 6.8 Hz); HRMS (FAB, direct) calcd for
C
36H71NO4, [M + H]+ 582.5461; found 582.5441 (100%). Anal.
Calcd: C, 74.30; H, 12.30; N, 2.41. Found: C, 74.15; H, 12.30;
N, 2.40.
Ack n ow led gm en t. We thank Dr. Yasuhara (Osaka
University) and Dr. Kiyomiya (Osaka Pref. University)
for the generous gifts of HL-60 cells and L-1210 cells.
(2S,3R,2′R,3′Z)-2-N-(2′-H yd r oxy-3′-oct a d ecen oyl)-[2-
a m in o-octa d eca n -1,3-d iol] (1c). The reaction was carried
out as described above, using R-Z-22 (220 mg, 0.351 mmol) to
give 1c (150 mg, 73%) as a powdery solid; mp 92-93 °C; [R]25
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra of
all new compounds 6, 7, R-Z-8, R-Z-9, R-Z-10, S-Z-14, R-Z-
20, S-Z-20, R-Z-21, S-Z-21, 1c, and 1d and of the eight known
compounds R-E-9, R-E-10, S-E-13, 19, R-E-20, S-E-20, 1a ,
and 1b. This material is available free of charge via the
Internet at http://pubs.acs.org.
D
-49.9 (c 0.5, CHCl3); IR (KBr) 3289, 2918, 2851, 1655, 1539,
1470, 1153, 1049, 980, 918, 719 cm-1 1H NMR (400 MHz,
;
CDCl3, 50 °C) δ 0.88 (t, 6 H, J ) 6.8 Hz), 1.26 (brs, 48 H),
1.38-1.46 (m, 1 H), 1.48-1.56 (m, 1 H), 2.22 (q, 2 H, J ) 8
Hz), 2.56 (d, 1 H, J ) 5.9 Hz), 2.71 (brs, 1 H), 3.18 (brs, 1 H),
3.72-3.84 (m, 3 H), 3.98 (d, 1 H, J ) 11.1 Hz), 4.87 (d, 1 H, J
) 8.8 Hz), 5.44 (dd, 1 H, J ) 9, 10.7 Hz), 5.77 (dt, 1 H, J )
J O0206824
J . Org. Chem, Vol. 68, No. 7, 2003 2797