Catalytic asymmetric syntheses of antifungal sphingofungins and their biological activity as potent inhibitors of serine palmitoyltransferase (SPT)

Article abstract of DOI:10.1021/ja9730829

Unambiguous synthetic routes to sphingofungins B and F and to their stereoisomers have been developed based on the tin(II)-catalyzed asymmetric aldol reaction (Chiral Lewis Acid-Controlled Synthesis (CLAC Synthesis)). Efficient enantioselective synthesis using a catalytic amount of a chiral source as well as the effectiveness of this strategy for the synthesis of the sphingofungin family have been successfully demonstrated. Using the stereoisomers of sphingofungin B synthesized, the relevance of its stereochemistry to its SPT inhibitory activity has been revealed.

Full text of DOI:10.1021/ja9730829

908
J. Am. Chem. Soc. 1998, 120, 908-919
Catalytic Asymmetric Syntheses of Antifungal Sphingofungins and
Their Biological Activity as Potent Inhibitors of Serine
Palmitoyltransferase (SPT)
Shuj Kobayashi,*,† Takayuki Furuta,† Takaomi Hayashi,† Masahiro Nishijima,‡ and
Kentaro Hanada‡
Contribution from the Department of Applied Chemistry, Faculty of Science, Science UniVersity of Tokyo
(SUT), Kagurazaka, Shinjuku-ku, Tokyo 162, Japan, and Department of Biochemistry and Cell Biology,
National Institute of Infectious Diseases, Toyama, Shinjuku-ku, Tokyo, 162, Japan
ReceiVed September 2, 1997
Abstract: Unambiguous synthetic routes to sphingofungins B and F and to their stereoisomers have been
developed based on the tin(II)-catalyzed asymmetric aldol reaction (Chiral Lewis Acid-Controlled Synthesis
(CLAC Synthesis)). Efficient enantioselective synthesis using a catalytic amount of a chiral source as well as
the effectiveness of this strategy for the synthesis of the sphingofungin family have been successfully
demonstrated. Using the stereoisomers of sphingofungin B synthesized, the relevance of its stereochemistry
to its SPT inhibitory activity has been revealed.
Introduction
center.1b In 1994, Mori et al. reported the first formal synthesis
of sphingofungin D from N-acetyl D-mannosamine and (R)-
epoxyoctane.4 They also prepared its C-14 isomer but could
find no difference between two steroisomers on which to base
assignment of the natural products stereochemistry. In 1995,
Chida and Ogawa et al. reported a total synthesis of sphingo-
fungin D from myo-inositol and (R)-epoxyoctane, and they also
determined the absolute stereochemistry of C-14.5 In this paper,
we report a general synthetic route to the sphingofungins and
their stereoisomers from simple achiral compounds via catalytic
asymmetric aldol reactions.6 The utility of the route has been
demonstrated by the catalytic asymmetric synthesis of sphin-
gofungins B and F and of their stereoisomers. Their SPT
inhibitory activity and the relevance of the stereochemistry has
also been investigated.
The sphingofungins are a new family of antifungal agents,
isolated by Merck’s group in 1992.1 They are sphingosine-
like compounds which potently inhibit serine palmitoyltrans-
ferase (SPT), an enzyme catalyzing the initial step in the
biosynthesis of sphingolipids (vide infra).2 Because of their
novel polyhydroxyamino acid structures containing five asym-
metric centers and of recent interest in the chemistry and
biochemistry of sphingolipids,3 there is a strong requirement
for synthesis of these natural products as well as related
compounds.
In the initial work, the relative and absolute stereochemistries
of sphingofungins A, B, C, and D were determined with the
exception of the absolute configuration of the C-14 stereogenic
† Science University of Tokyo.
‡ National Institute of Infectious Diseases.
Results and Discussion
§ Former National Institute of Health.
(1) (a) VanMiddlesworth, F.; Giacobbe, R. A.; Lopez, M.; Garrity, G.;
Bland, J. A.; Bartizal, K.; Fromtling, R. A.; Polishook, J.; Zweerink, M.;
Edison, A. M.; Rozdilsky, W.; Wilson, K. E.; Monaghan, R. L. J. Antibiot.
1992, 45, 861. Structure elucidation (b) VanMiddlesworth, F.; Dufresne,
C.; Wincott, F. E.; Mosley, R. T.; Wilson, K. E. Tetrahedron Lett. 1992,
33, 297.
Synthesis of Sphingofungin B and Its Stereoisomers. Our
retrosynthetic analysis for sphingofungin B is shown in Scheme
1. Sphingofungin B consists of three parts; a glycine head part,
a triol part containing three contiguous asymmetric centers and
a trans olefin, and a hydrophobic side chain. We planned to
connect the three parts successively. The final stage was
envisaged as an aldol reaction of a glycine enolate with 10,
which would be prepared by alkylation of 13 with 12. While
alkyl bromide 12 would be synthesized from 14, acetylene 13
would be prepared from 15 whose four stereoisomers can be
readily prepared by tin(II)-catalyzed asymmetric aldol reactions
using chiral Lewis acid-controlled synthesis (CLAC synthesis).7
Because the reaction of 10 with 11 can be controlled to afford
each of the four stereoisomers selectively and, moreover, amino
(2) Zweerink, M. M.; Edison, A. M.; Well, G. B.; Pinto, W.; Lester, R.
L. J. Biol. Chem. 1992, 267, 25032.
(3) Reviews: (a) Merrill, A. H., Jr.; Sweeley, C. C. In Biochemistry of
Lipids, Lipoproteins and Membranes; Vance, D. E., Vance, J., Eds; Elsevier
Science B. V.: Amsterdam, 1996; pp 309-339. (b) Hannun, Y. A. Science
1996, 274, 1855. See, also: (c) Hannun, Y. A.; Loomis, C. R.; Merrill, A.
H. Jr.; Bell, R. M. J. Biol. Chem. 1986, 261, 12604. (d) Okazaki, T.; Bell,
R. M.; Hannun, Y. A. J. Biol. Chem. 1989, 264, 19076. (e) Hanada, K.,
Nishijima, M., Kiso, M., Hasegawa, A., Fujita, S., Ogawa, T., and Akamatsu,
Y. J. Biol. Chem. 1992, 267, 23527. (f) Zhang, H.; Desai, N. N.; Olivera,
A.; Seki, T.; Brooker, G.; Spiegel, S. J. Cell Biol. 1991, 114, 155. (g) Wang,
E.; Norred, W. P.; Bacon, C. W.; Riley, R. T.; Merrill, A. H., Jr. J. Biol.
Chem. 1991, 266, 14486. (h) Obeid, L. M.; Linardic, C. M.; Karolak, L.
A.; Hannun, Y. A. Science 1993, 259, 1769. (i) Joseph, C. K.; Wright, S.
D.; Bornmann, W. G.; Randolph, J. T.; Kumar, E. R.; Bittman, R.; Liu, J.;
Kolesnick, R. N. J. Biol. Chem. 1994, 269, 17606. (j) Wiegmann, K.;
Schutze, S.; Machleidt, T.; Witte, D.; Kronke, M. Cell 1994, 78, 1005. (k)
Miyake, Y.; Koizumi, Y.; Nakamura, S.; Fujita, T.; Kawasaki, T. Biochem.
Biophys. Res. Commun. 1995, 211, 396. (l) Pinto, W. J., Wells, G. W.,
Lester, R. L. J. Bacteriol. 1992, 174, 2575.
(4) Mori, K.; Otaka, K. Tetrahedron Lett. 1994, 35, 9207.
(5) Chida, N.; Ikemoto, H.; Noguchi, A.; Amano, S.; Ogawa, S. Natural
Product Lett. 1995, 6, 295.
(6) Preliminary communications: (a) Kobayashi, S.; Hayashi, T.; Iwa-
moto, S.; Furuta, T.; Matsumura, M. Synlett 1996, 672. (b) Kobayashi, S.;
Matsumura, M.; Furuta, T.; Hayashi, T.; Iwamoto, S. Synlett 1997, 301.
S0002-7863(97)03082-5 CCC: $15.00 © 1998 American Chemical Society
Published on Web 01/27/1998

Syntheses of Antifungal Sphingofungins
J. Am. Chem. Soc., Vol. 120, No. 5, 1998 909
Chart 1. Sphingosine Family
Scheme 2a
Scheme 1. Retrosynthetic Analysis
a (a) Sn(OTf)2 (20 mol %), (R)-1-methyl-2-[(N-1-naphthylamino)-
methyl]pyrrolidine (24 mol %), SnO (20 mol %), C2H5CN, -78 °C,
slow addition for 4 h, 87%, syn/anti ) 97/3, 91% ee (syn); (b) CH2Cl2,
-78 °C; (c) TsOH (catalyst), DMF, 97%, (d) CH2Cl2, 97%; then
recrystallized from hexane, 89%; (e) THF-HMPA, -78 °C to room
temperature; (f) Et3N, DMAP (catalyst), CH2Cl2, 0 °C; (g) THF, reflux;
(h) imidazole, DMF, 98% (three steps); (i) Et3N, CH2Cl2, -50 °C,
>95%; (j) THF, -78 °C, 93%, 67% ds; (k) CH2Cl2, 85%; (l) THF-
H2O, 0 °C; (m) THF, 93% (two steps); (n) liquid NH3-THF, -50 °C.
biological activity. The synthesis was performed according to
Scheme 2. Phenyl ester 15 was prepared from trimethylsilyl-
propynal (18) and (Z)-2-benzyloxy-1-phenoxy-1-trimethylsi-
loxyethene (19) via a tin(II)-catalyzed asymmetric aldol reaction
as a key step.7-9 It should be noted that all the stereoisomers
of 15 can be selectively prepared based on this methodology.
Phenyl ester 15 was reduced using DIBAL to give diol 20, which
was protected as its acetonide 21, after which desilylation with
tetrabutylammonium fluoride gave 13. Acetylene 13 was
isolated as white crystals and could be purified by recrystalli-
zation (>99% de, >99% ee). After introduction of the C-13
side unit giving 22, the acetonide group was removed under
(7) (a) Kobayashi, S.; Horibe, M. J. Am. Chem. Soc. 1994, 116, 9805.
(b) Kobayashi, S.; Hayashi, T. J. Org. Chem. 1995, 60, 1098. (c) Kobayashi,
S.; Horibe, M.; Matsumura, M. Synlett 1995, 675. (d) Kobayashi, S.; Horibe,
M. Tetrahedron Asym. 1995, 6, 2565. (e) Kobayashi, S.; Horibe, M. Chem.
Lett. 1995, 1029. (f) Kobayashi, S.; Horibe, M. Tetrahedron 1996, 52, 7277.
(g) Kobayashi, S.; Horibe, M. Chem. Eur. J. in press. See, also: (h)
Kobayashi, S.; Ishitani, H. J. Am. Chem. Soc. 1994, 116, 4083. (i)
Kobayashi, S.; Ishitani, H.; Hachiya, I.; Araki, M. Tetrahedron 1994, 50,
11623. (j) (g) Kobayashi, S.; Kawasuji, T.; Mori, N. Chem. Lett. 1994,
217.
acids other than glycine such as serine (sphingofungin E) or
alanine (sphingofungin F) could be introduced in this step, this
route could be applied to the synthesis of stereoisomers and
other members of the sphingofungin family.
At the time this research project was started the absolute
configuration of C-14 of sphingofungin B had not yet been
determined. We set out to synthesize 14-deoxy sphingofungin
B first, as a model study for the synthesis of sphingofungin B
as well as to examine the effect of the 14-hydroxyl group on
(8) Kobayashi, S.; Kawasuji, T. Synlett. 1993, 911.
(9) We have previously prepared sphingosine and phytosphingosine using
catalytic asymmetric aldol reactions. Kobayashi, S.; Hayashi, T.; Kawasuji,
T. Tetrahedron Lett. 1994, 35, 9573.

910 J. Am. Chem. Soc., Vol. 120, No. 5, 1998
Kobayashi et al.
Table 1
Figure 1.
acidic conditions to give diol 23. The primary hydroxyl group
of 23 was protected as its mono-p-methoxytrityl (MMTr) ether,
the acetylene part of 23 was reduced to the trans olefin by
lithium aluminum hydride (LAH),10 and the free secondary
alcohol was protected as its tert-butyldimethylsilyl (TBS) ether.
Deprotection of the MMTr group followed by Swern oxidation
gave the key aldehyde 26.
Scheme 3a
The aldol reaction of 26 with the glycine enolate derived from
1111 was examined under several conditions (Table 1). When
the glycine zinc enolate, which was prepared from the glycine
lithium enolate and zinc chloride, was used in THF, the desired
adduct (27c) was obtained in high yield with good selectivity
(after protection of the amino group using Boc2O). It was also
found that the four stereoisomers could be easily separated at
this stage by silica gel column chromatography. The stereo-
chemical assignments were made by NOE experiments after
conversion to δ-lactones (Figure 1).12 In addition, the isomeric
27a was obtained in good selectivity when 26 was reacted with
the glycine lithium enolate in THF-HMPA. On the other hand,
isomeric 27d was produced with good selectivity when 26 was
reacted with the silyl enolate derived from 11 under the influence
of BF3‚OEt2. These selectivities using the zinc enolate and the
silyl enol ether/BF3‚OEt2 can be explained by assuming the
following chelation and acyclic transition models, respectively.13
It should be noted that in both cases, re face of the aldehyde 26
reacted selectively.14
a (a) Sn(OTf)2 (20 mol %), (S)-1-methyl-2-[(N-1-naphthylamino)-
methyl]pyrrolidine (24 mol %), SnO (20 mol %), CH2Cl2, -78 °C,
slow addition for 4 h, 87%, 94% ee; (b) i-Pr2NEt, CH2Cl2; (c) THF, 0
°C, 98%; (d) CH2Cl2, 0 °C; (e) BuLi, THF-HMPA, 78 °C to room
temperature; (f) EtOH, 96%; (g) CH2Cl2, 0 °C.
cleaved under Birch conditions, and finally the Boc group was
removed with trifluoroacetic acid (TFA) to give 14-deoxysph-
ingofungin B (30).
We next undertook the synthesis of sphingofungin B (Schemes
3 and 4). The chiral hydrophobic chain 12 was prepared
according to Scheme 3. The tin(II)-catalyzed asymmetric aldol
reaction was a powerful tool again, and the thioester 14 was
obtained in 94% ee from the achiral compounds, heptanal (16)
and 1-ethylthio-1-trimethylsiloxyethene (17). The hydroxyl
group of 14 was protected as its MOM ether, and the thioester
group was reduced using LAH. Alcohol 33 was brominated to
give alkyl bromide 34 and the coupling reaction of 34 with
4-benzyloxy-1-butyne proceeded smoothly in THF-HMPA to
give alkyne 35. Reduction of the alkyne of 35 and deprotection
of the benzyl ether were carried out in one pot using Pd/C under
an H2 atmosphere. The resulting alcohol (36) was brominated
Hydrolysis of the ethyl ester followed by deprotection of the
TBS ether afforded carboxylic acid 28. The benzyl ether was

Syntheses of Antifungal Sphingofungins
J. Am. Chem. Soc., Vol. 120, No. 5, 1998 911
Scheme 4a
Table 2
(Table 2). When the glycine zinc enolate was used, the desired
adduct (42c) was obtained in high yield with good selectivity.
While the isomeric 42a was obtained in good selectivity when
10 was reacted with the glycine lithium enolate in THF-HMPA,
isomeric 42d was produced with good selectivity when 10 was
reacted with the silyl enolate derived from 11 under the influence
of BF3‚OEt2. The four stereoisomers could be easily separated
by silica gel column chromatography. Furthermore, the reac-
tions of 10 with the bislactim ether prepared from either D- or
L-valine and glycine ethyl ester15 were examined (Table 3). It
was found that the tin(II) aza-enolate, which was prepared from
the lithium enolate of the D-lactim ether and tin(II) chloride,
reacted with 10 to afford 46b in quantitative yield with complete
diastereoselectivity. Similarly, L-valine was used to obtain 46d
quantitatively. In these reactions, the stereochemistry of the
C-2 stereogenic centers of the products were derived from those
of the bislactim ether and hence from the D- or L-valine used.
While the adduct predicted by the Felkin-Anh model was
obtained using the tin(II) aza-enolate, the adduct predicted by
the chelation model was predominantly obtained using the zinc
aza-enolate.16 46b-d were readily converted to carboxylic acid
esters 42b-d.
Hydrolysis of the resulting ester 42c and deprotection of the
TBS groups with tetrabutylammonium fluoride afforded car-
boxylic acid 43c. After removal of the Boc group with TFA,
the benzyl ether was finally cleaved under Birch conditions.
Sphingofungin B (4) was obtained after purification using
reverse-phase column chromatography.17 Its spectral and
chromatographic properties are identical with those of an
authentic sample of the natural product. Similarly, 42a, 42b,
and 42d were converted to stereoisomers of 4a, 4b, and 4d,
respectively, and by similar routes the stereoisomers 4e, 4f, and
4g were also prepared.
a (a) THF-HMPA, -78 °C to 0 °C; (b) MeOH, 94%; (c) Et3N,
DMAP (catalyst), CH2Cl2, 0 °C; (d) LAH, THF, reflux; (e) imid., DMF,
93% (two steps); (f) HCOOH:Et2O (1:2), 85%; (g) Et3N, CH2Cl2, -50
°C; (h) ZnCl2, THF, -78 °C, 93%, 56% ds; (i) CH2Cl2, 61%; (j) THF-
H2O, 0 °C; (k) THF, 60 °C, 96% (two steps); (l) TFA:CH2Cl2 (1:1), 0
°C, quant.; (m) liquid NH3-THF, -50 °C.
with carbon tetrabromide (CBr4) and triphenylphosphine (Ph3P)
to give the desired chiral hydrophobic chain (12) in high yield
(Scheme 3). This chiral chain was then coupled with 13 to
afford ether 37, which was treated with concentrated HCl to
produce 38. Triol 38 was converted to aldehyde 10 in five steps
(Scheme 4). The primary hydroxyl group of 38 was protected
as its MMTr ether, the acetylene was reduced to the trans olefin
with LAH, and the free secondary hydroxyl groups were
protected as their TBS ethers. The MMTr group was selectively
deprotected under mild acidic conditions to give alcohol 41.
Swern oxidation of 41 then gave the key aldehyde 10.
It was found that the selectivities observed in the aldol
reaction of 10 with the glycine enolate derived from 11 was
similar to those in the reaction of 26 with the glycine enolate
(10) Rossi, R.; Carpita, A. Synthesis 1977, 561.
(11) Djuric, S.; Venit, J.; Magnus, P. Tetrahedron Lett. 1981, 22, 1787.
(12) Ishihara, K.; Kubota, M.; Kurihara, H.; Yamamoto, H. J. Org. Chem.
1996, 61, 4560.
(13) Reetz, M. T. Angew. Chem., Int. Ed. Engl. 1984, 23, 556 and
references therein.
(14) Complete re face selectivity was observed in the model reaction of
26 with 1-ethylthio-1-trimethylsiloxyethene under the influence of a Lewis
acid.
Inhibition of SPT Activity by Stereoisomers of Sphingo-
fungin B. The biosynthesis of sphingolipids starts from the
(15) (a) Scho¨llkopf, U. Pure Appl. Chem. 1983, 55, 1799. (b) Scho¨llkopf,
U.; Hartwig, W.; Groth, U.; Westphalen, K. Liebigs Ann. Chem. 1981, 696.
(16) Cf.: Ruiz, M.; Ojea, V.; Quintela, J. M. Tetrahedron Lett. 1996,
37, 5743.
(17) Kurosawa, K.; Ohfune, Y. J. Am. Chem. Soc. 1986, 108, 6041. We
are grateful to Professor Y. Ohfune for helpful discussion on isolation of
sphingofungin B. As for the remote chiral center (C-14) of the synthetic
sphingofungin B (4), 3% of its epimer was included.

912 J. Am. Chem. Soc., Vol. 120, No. 5, 1998
Kobayashi et al.
Table 3
Table 4. Inhibition of SPT Activity by Stereoisomers of
Sphingofungin Ba
compd
ID50 value for SPT activity/nM
4
4e
30
4d
4b
4a
4f
16.6 ( 0.8
17.1 ( 0.6
3590 ( 150
238 ( 16
3080 ( 360
10000 ( 1000
>10000
4g
>10000
a SPT activity of membranes exposed to stereoisomers of sphingo-
fungin B at various concentrations (0-10 µM) was determined as
described under Experimental Procedures. The data shown are the mean
values (SD of the ID50 values from triplicate experiments.
Chart 2. Sphingofungin B and Stereoisomers
condensation of palmitoyl-CoA with serine, which is catalyzed
by serine palmitoyltransferase (SPT).3a The fact that cell
mutants defective in SPT require exogenous sphingolipids for
growth of the cells has revealed that sphingolipids are essential
for growth of various types of cells.3a,3l Significant roles of
sphingolipids have been indicated in various cellular events
including proliferation, differentiation, death, and inflammatory
responses.3 Sphingofungin B was reported to inhibit SPT, and
it has a striking resemblance to sphingosine and its biosynthetic
intermediates. Although the five stereogenic centers of sphin-
gofungin B would be expected to play important roles in its
biological activity, the effect of their chirality on activity has
not yet been investigated.
Structure-activity relationships of sphingofungin B as an
inhibitor of SPT were examined using the synthesized stereo-
isomers. Natural type sphingofungin B (4) inhibited SPT
activity with a dose producing 50%-inhibition (ID50) of about
15 nM, confirming it as a potent SPT inhibitor. The C-14
hydroxyl group stereoisomer (4e) inhibited SPT activity similar
to 4, whereas dehydroxylation of C-14 (30) markedly weakened
the observed inhibition (Table 4). In contrast, the C-3 hydroxyl
group stereoisomer (4b) was about 200-fold less efficient in
inhibiting SPT, and the C-2 amino group stereoisomer (4d) was
14-fold less efficient than 4 (Table 4). Simultaneous isomer-
ization of both C-2 amino and C-3 hydroxyl groups (4a), or
both C-4 and C-5 hydroxyl groups (4g), further weakened SPT
inhibition. It is noted that the enantiomer of sphingofungin B
(4f) was virtually inactive as an SPT inhibitor (Table 4).
4d, 30 > 4a, 4f, 4g) similar to that observed under the cell-free
SPT assay conditions described above.
These results indicate that (i) the C-14 hydroxyl group of
sphingofungin B is relevant to potent SPT inhibition, but that
its stereoconfiguration is not crucial for activity, and that (ii)
the stereoconfigurations of the other chiral centers (C-2, -3, -4,
and -5) are relevant to activity. The stereochemical requirements
of the C-2 amino and C-3 hydroxyl groups for potent activity
may suggest that sphingofungin B mimics a transition state
intermediate of the SPT reaction.3a,18
Synthesis of Sphingofungin F (the Determination of Its
Stereochemistry). Our basic strategy shown in Scheme 1
should be useful not only for the synthesis of sphingofungin B
and its stereoisomers but also with minor modification for the
synthesis of related compounds. Simply changing the amino
acid part and the hydrophobic side chain is required. To
We also examined the effect of these compounds on sphin-
golipid biosynthesis in intact cells by metabolic labeling of lipids
in CHO-K1 cells with radioactive serine and observed that they
inhibited sphingolipid biosynthesis in the order (4, 4e . 4b,
(18) Krisnangkura, K.; Sweeley, C. C. J. Biol. Chem. 1976, 251, 1597.

Syntheses of Antifungal Sphingofungins
J. Am. Chem. Soc., Vol. 120, No. 5, 1998 913
Scheme 5a
Scheme 6a
a (a) THF -78 °C, 92%; (b) THF; (c) EtOH (70% aqueous), room
temperature; (d) 0.5 N NaOH, MeOH, 55% (two steps); (e) liquid NH3-
THF, -50 °C, 44%; (f) EtOH (70% aqueous), 100 °C.
demonstrate the utility of this strategy, we undertook the total
synthesis of sphingofungin F (8).19 This compound was isolated
from a fermentation of Poecilomyces Variotii. While it bears a
strong structural resemblance to myriocin,20 its stereochemistry
has not yet been determined.
First, the synthesis of 14-deoxy sphingofungin F was carried
out (Scheme 5). A key step is the aldol reaction of 26 with an
alanine enolate. After several trials, we found a tin(II) aza-
enolate of Scho¨lkopf’s bislactim ether 4714,21 reacted with 26
to afford the desired adduct in 92% yield (diastereomer ratio )
45:42:13:0). After the TBS group of the major stereoisomer
was removed, the resulting diol was treated with p-toluene-
sulfonic acid in aqueous ethanol and then NaOH in methanol
to afford amino acid 50. Finally, deprotection of the benzyl
ether was performed under Birch conditions to give 14-deoxy
sphingofungin F (51). 1H and 13C NMR of synthetic 51 were
very similar to those of sphingofungin F. The stereochemistry
was finally determined by NOE experiments after conversion
to lactone 52. This clarified that the absolute configuration of
the contiguous chiral centers of 51 is similar to that of
sphingofungin B and myriocin.
We then undertook the synthesis of sphingofungin F. The
hydrophobic side chain was prepared according to Scheme 6.
The Yb(OTf)3-catalyzed aldol reaction22 was very useful for
the preparation of 14. The route from racemic 14 to alkyl
(19) Horn, W. S.; Smith, J. L.; Bills, G. F.; Raghoobar, S. L.; Helms, G.
L.; Kurtz, M. B.; Marrinan, J. A.; Frommer, B. R.; Thornton, R. A.;
Mandala, S. M. J. Antibiotics 1992, 45, 1692.
(20) (a) Kluepfel, D.; Bagli, J.; Baker, H.; Charest, M. P.; Kudelski, A.;
Sehgal, S. N.; Ve´zina, C. J. Antibiotics 1972, 25, 109. (b) Aragozzini, F.;
Manachini, P. L.; Craveri, R.; Rindone, B.; Scolastico, C. Tetrahedron 1972,
28, 5493. (c) Destro, R.; Colombo, A. J. Chem. Soc., Perkin Trans 2 1979,
896. (d) Fujita, T.; Inoue, K.; Yamamoto, S.; Ikumoto, T.; Sasaki, S.;
Toyama, R.; Chiba, K.; Hoshino, Y.; Okumoto, T. J. Antibiotics 1994, 47,
208.
(21) Cf.: Sano, S.; Kobayashi, Y.; Kondo, T.; Takebayashi, M.;
Maruyama, S.; Fujita, T.; Nagao, Y. Tetrahedron Lett. 1995, 36, 2097.
(22) (a) Kobayashi, S.; Hachiya, I.; Takahori, T. Synthesis 1993, 371.
(b) Kobayashi, S. Synlett 1994, 689.
a (a) CH2Cl2 0 °C; (b) MeOH, 50 °C, quant.; (c) Et3N, CH2Cl2, room
temperature; (d) THF-HMPA, 78 °C to 0 °C, 89%; (e) THF, room
temperature, quant.; (f) Et3N, CH2Cl2, -78 °C to -50 °C; (g) 3 N
HCl, THF, room temperature, 99%; (h) catalyst TMSOTf, CH2Cl2, 0
°C; (i) Et3N, DMAP (catalyst), CH2Cl2, 0 °C; (j) THF, reflux; (k) imid.,
DMF, 91% (three steps); (l) HCOOH:Et2O (1:2); (m) Et3N, CH2Cl2,
-50 °C; (n) 47, BuLi, SnCl2, THF, -78 °C, 83%; (o) THF; (p) THF-
H2O (7:3), 0 °C; (q) 5 N NaOH, MeOH, room temperature, 58% (two
steps); (r) CH2Cl2, -78 °C.

914 J. Am. Chem. Soc., Vol. 120, No. 5, 1998
Kobayashi et al.
serine to the medium, the cells were incubated at 37 °C for 2 h, and
bromide 12 was performed according to Scheme 3 (asymmetric
synthesis). After deprotection of the MOM ether of 12, the
resulting alcohol (53) was protected as its TMS ether giving
54. Bromide 54 was then coupled with 13 to afford 55. The
trimethylsilyl group of 55 was deprotected, the resulting alcohol
(56) was oxidized (57), and this ketone was treated with HCl
to give diol 58. After the ketone group of 58 had been protected
(59), the primary hydroxyl group was protected with MMTrCl.
Reduction of the alkyne to the trans olefin was carried out using
LAH, and the secondary alcohol was protected as its TBS ether
(60). Deprotection of the MMTr ether followed by Swern
oxidation gave key aldehyde 62.
lipid extracted from the cells were analyzed as described previously.24
Phenyl (2R,3S)-2-benzyloxy-3-hydroxy-5-trimethylsilylpent-4-
ynoate (15): To a mixture of tin(II) trifluoromethansulfonate25 (834
mg, 2.0 mmol) and tin(II) oxide (269 mg, 2.0 mmol) in propionitrile
(20 mL) was added (R)-1-methyl-2-[(N-1-naphthylamino)methyl]pyr-
rolidine26 (576 mg, 2.4 mmol) in propionitrile (20 mL) at room
temperature. The solution was cooled to -78 °C, and 18 (1.26 g, 10
mmol) in propionitrile (15 mL) and 19 (3.77 g, 12 mmol) in propionitrile
(15 mL) were slowly added over 4 h. After the solution was stirred
for 1 h at -78 °C, it was saturated with aqueous NaHCO3 solution
which was added to quench the reaction. The organic layer was
separated, and the aqueous layer was extracted with ether. The ethereal
extract was washed with water and brine, dried over sodium sulfate,
and concentrated under reduced pressure. The residue was treated with
THF:1 N HCl ) 4:1 solution for 30 min. After neutralization using
saturated aqueous NaHCO3 solution, the aqueous layer was extracted
with ether. The ethereal extract was washed with water and brine,
dried over sodium sulfate, and concentrated. The residue was purified
by column chromatography on silica gel (hexane/ethyl acetate ) 20/
The aldol-type reaction of 62 with the tin(II) azaenolate of
47 proceeded smoothly to afford the desired adduct (63) in 83%
yield with good diastereoselectivity (70:25:5:0, Scheme 6). After
deprotection of the TBS group, successive hydrolysis (two steps)
of the major diastereomer and finally deprotection of the benzyl
ether using BCl3 worked well to afford sphingofungin F (8).
Its spectral properties are completely identical with those in the
literature.19 It is now confirmed unambiguously that the
structure of sphingofungin F, including the absolute configu-
ration of its chiral centers, is similar to that of sphingofungin B
and myriocin.
1) to give 15 (3.21 g, 87%, syn/anti ) 97/3, 91% ee (syn)) as a white
27
solid. [R]D +28.8 (c ) 1.03, CHCl3); IR (neat) 1643, 3379 cm-1
;
1H NMR δ 0.02 (s, 9H), 2.91 (d, 1H, J ) 8.1 Hz), 4.13 (d, 1H, J ) 4.4
Hz), 4.56 (d, 1H, J ) 11.9 Hz), 4.69 (dd, 1H, J ) 4.4, 8.1 Hz), 4.77
(d, 1H, J ) 11.9 Hz), 6.93-7.29 (m, 10H); 13C NMR δ -0.4, 64.0,
73.4, 80.6, 91.7, 102.0, 121.2, 126.1, 128.19, 128.24, 128.4, 129.4,
136.5, 150.1, 168.0. Anal. Calcd for C21H24O4Si: C, 68.45; H, 6.56.
Found: C, 68.59; H, 6.51. The enantiomeric excess was determined
by HPLC analysis. HPLC (Daicel Chiralcel AD, hexane/i-PrOH )
24/1, flow rate ) 1.0 mL/min): tR ) 17.5 min (2S,3R), tR ) 21.2 min
(2R,3S).
Conclusions
In summary, we have developed an unambiguous synthetic
route to sphingofungins B and F and their derivatives. The
synthesis is based on the catalytic asymmetric aldol reaction,
and efficient enantioselective synthesis using a catalytic amount
of a chiral source as well as the effectiveness of our synthetic
strategy for the sphingofungin family (Scheme 1) has been
successfully demonstrated. By using the stereoisomers of
sphingofungin B, the relevance of the stereochemistry of its
chiral centers to SPT inhibitory activity was revealed.
(2S,3S)-2-Benzyloxy-5-trimethylsilylpent-4-yne-1,3-diol (20): To
a solution of 15 (3.21 g, 8.7 mmol) in dichloromethane (80 mL) was
added diisobutylalminum hydride (1.5 M solution in toluene, 17.4 mL)
over 20 min at -78 °C. After stirring for 30 min at -78 °C, the mixture
was diluted with 1 N HCl. After the organic layer was separated, the
aqueous layer was extracted with dichloromethane. The combined
organic layer was washed with water and brine, dried over sodium
sulfate, and concentrated under reduced pressure. The residue was
purified by column chromatography on silica gel (hexane/ethyl acetate
) 6/1) to give 20 (2.01 g, 83%) as a white solid. [R]27 +13.0 (c )
D
Experimental Section
1.02, C6H6); IR (neat) 2171, 3363 cm-1; 1H NMR δ 0.19 (s, 9H), 2.08
(brs, 1H), 2.69 (brs, 1H), 3.63 (ddd, 1H, J ) 5.0, 5.0, 5.0 Hz), 3.56
(dd, 1H, J ) 5.0, 11.6 Hz), 3.64 (dd, 1H, J ) 5.0, 11.6 Hz), 4.30 (brs,
1H), 4.73 (d, 1H, J ) 11.4 Hz), 4.83 (d, 1H, J ) 11.4 Hz), 7.33-7.38
(m, 5H); 13C NMR δ -0.3, 61.7, 63.2, 73.6, 81.7, 91.5, 103.6, 128.0,
128.1, 128.6, 137.7. Anal. Calcd for C15H22O3Si: C, 64.71; H, 7.96.
Found: C, 64.84; H, 7.95.
General Methods. Melting points are uncorrected. IR spectra were
recorded on a Horiba FT-300. 1H and 13C NMR spectra were recorded
on a JEOL JNR-EX270L, JNM-LA300, or a JNM-LA400 spectrometer
in CDCl3 unless otherwise noted. Tetramethylsilane (TMS) served as
internal standard (δ ) 0) for 1H NMR, and CDCl3 was used as internal
standard (δ ) 77.0) for 13C NMR. When CD3OD was used, CD3OD
(4S,5S)-5-Benzyloxy-4-(2-trimethylsilylethynyl)-2,2-dimethyl-1,3-
dioxane (21): To a solution of 20 (2.01 g, 7.2 mmol) in N,N-
dimethylformamide (50 mL) was added a solution of 2,2-dimethoxy-
propane (2.2 g, 21.6 mmol) in N,N-dimethylformamide (10 mL) and
cat p-TsOH at room temperature. After stirring for 10 h, the reaction
was quenched with saturated aqueous NaHCO3. The organic layer was
separated, and the aqueous layer was extracted with ether. The ethereal
extract was washed with water and brine, dried over sodium sulfate,
and concentrated under reduced pressure. The residue was purified
by column chromatography on silica gel (hexane/ethyl acetate ) 30/
1) to give 21 (2.18 g, 95% (syn); 0.06 g, 3% (anti)) as a white solid.
[R]D26 +37.0 (c ) 2.13, CHCl3); 1H NMR δ 0.00 (s, 9H), 1.22 (s, 3H),
1.32 (s, 3H), 3.22 (dd, 1H, J ) 3.0, 5.9 Hz), 3.64 (dd, 1H, J ) 3.0,
12.5 Hz), 3.72 (dd, 1H, J ) 3.3, 12.5 Hz), 4.59-4.60 (m, 3H), 7.09-
7.24 (m, 5H); 13C NMR δ -0.3, 17.8, 20.3, 61.6, 64.1, 70.9, 71.7,
1
served as internal standard (δ ) 3.3 for H NMR (CH3OH) and δ )
49.0 for 13C NMR). Mass spectra were measured on a JEOL DX-
303HF spectrometer. HPLC was carried out using a Hitachi LC-
Organizer, L-4000 UV Detector, L-6200 Intelligent Pump, and D-2500
Chromato-Integrator. Optical rotations were recorded on a Jasco DIP-
360 digital polarimeter. Column chromatography was performed on
Silica gel 60 (Merck) or Wakogel B5F. All solvents were purified
according to standard procedures.
Membranes were prepared from CHO-K1 cells as described
previously.23 Membranes (1 mg of protein/mL) were incubated in 50
mM Hepes-Na (pH 7.5) containing 5 mM EDTA, 0.1% sucrose
monolaurate, and various concentrations of sphingofungin B isomers
at 4 °C for 30 min. A concentration of dimethyl sulfoxide, in which
sphingofungin B isomers were dissolved, was adjusted to be 1% in the
membrane incubation. After the incubation, SPT activity of the
membranes were determined as described previously.20 For examina-
tion of sphingolipid synthesis in intact cells, CHO-K1 cells were
preincubated in F-12 medium containing various concentrations of
sphingofungin B isomers at 37 °C for 1 h. After addition of L-[14C]-
(24) Hanada, K., Nishijima, M., and Akamatsu, Y. J. Biol. Chem. 1990,
265, 22137.
(25) (a) Batchelor, R. J.; Ruddick, J. N. R.; Sams, J. R.; Aubke, F. Inorg.
Chem. 1977, 16, 1414. (b) Mukaiyama, T.; Iwasawa, N.; Stevens, R. W.;
Haga, T. Tetrahedron 1984, 40, 1381.
(26) (a) Kobayashi, S.; Uchiro, H.; Fujishita, Y.; Shiina, I.; Mukaiyama,
T. J. Am. Chem. Soc. 1991, 113, 4247. (b) Mukaiyama, T.; Kobayashi, S.;
Sano, T. Tetrahedron 1990, 46, 4653
(23) Hanada, K., Horii, M., Akamatsu, Y. Biochim. Biophys. Acta 1991,
1086, 151.

Syntheses of Antifungal Sphingofungins
J. Am. Chem. Soc., Vol. 120, No. 5, 1998 915
91.5, 99.6, 101.4, 127.7, 127.9, 128.3, 138.0. Anal. Calcd for
C18H26O3Si: C, 67.88; H, 8.23. Found: C, 68.01; H, 8.16.
aqueous, the suspension was stirred vigorously, and the aqueous layer
was extracted with ether. The ethereal extract was washed with water
and brine, dried over sodium sulfate, and concentrated under reduced
pressure. The residue was purified by column chromatography on silica
gel (hexane/ethyl acetate ) 6/1) to give 33 (869.8 mg, 98%) as a
colorless oil. [R]D25 -27.0 (c ) 1.67, C6H6); IR (neat) 2929.3, 3392.2
(4S,5S)-5-Benzyloxy-4-ethynyl-2,2-dimethyl-1,3-dioxane (13) (100%
ee): To a solution of 21 (2.18 g, 6.8 mmol) in dichloromethane (50
mL) was added a solution of tetrabutylammoniumfluoride (1.96 g, 7.5
mmol) in dichloromethane (10 mL) at room temperature. After having
been stirred for 30 min, the reaction was quenched with phosphate
buffer (pH ) 7), and the aqueous layer was extracted with dichlo-
romethane. The extract was dried over sodium sulfate and concentrated
under reduced pressure. The residue was purified by column chro-
matography on silica gel (hexane/ethyl acetate ) 6/1) to give 13 (1.62
g, 97%) as white crystals. The crystals were recrystallized from hexane
to give optically pure 13 (>99% ee, 1.49 g, 89%). Mp 96-98 °C;
[R]D27 +34.3 (c ) 1.21, CHCl3); IR (KBr) 2117, 3220 cm-1; 1H NMR
δ 1.43 (s, 3H), 1.54 (s, 3H), 2.57 (d, 1H, J ) 2.3 Hz), 3.45 (dd, 1H,
J ) 3.1, 4.0 Hz), 3.86 (dd, 1H, J ) 3.1, 12.5 Hz), 3.93 (dd, 1H, J )
4.0, 12.5 Hz), 4.78-4.80 (m, 3H), 7.26-7.44 (m, 5H); 13C NMR δ
21.0, 27.4, 61.5, 63.6, 70.7, 71.9, 75.0, 80.0, 99.6, 127.8, 128.0, 128.3,
137.9; HRMS calcd for C15H18O3 (M + H) 247.1335, found 247.1338.
Anal. Calcd for C15H18O3: C, 73.15; H, 7.37. Found: C, 72.85; H,
7.57. HPLC (Daicel Chiralcel AD, hexane/i-PrOH ) 50/1, flow rate
) 0.5 mL/min): tR ) 22.5 min (4S,5S), tR ) 26.3 min (4R,5R).
Ethyl (3R)-3-hydroxynonanethioate (14): To a mixture of tin(II)
trifluoromethansulfonate (417 mg, 1.0 mmol) and tin(II) oxide (135
mg, 1.0 mmol) in dichloromethane (10 mL) was added (S)-1-methyl-
2-[(N-1-naphthylamino)methyl]pyrrolidine (288 mg, 1.2 mmol) in
dichloromethane (10 mL) at room temperature. The solution was
cooled to -78 °C, and a solution of 16 (570 mg, 5.0 mmol) and 17
(1.06 mg, 6.0 mmol) in dichloromethane (15 mL) was slowly added
over 4 h. After stirring for 1 h at -78 °C, the reaction was quenched
with aqueous NaHCO3 solution, and the aqueous layer was extracted
with ether. The ethereal extract was washed with water and brine,
dried over sodium sulfate, and concentrated under reduced pressure.
The residue was treated with THF:1 N HCl ) 4:1 solution for 30 min,
and the mixture was extracted with ether. The ethereal extract was
washed with water and brine, dried over sodium sulfate, and concen-
trated, and the residue was purified by column chromatography on silica
gel (hexane/ethyl acetate ) 20/1) to give 14 (950 mg, 87%, 94% ee)
1
cm-1; H NMR δ 0.87 (t, 3H, J ) 6.9 Hz), 1.29 (s, 8H), 1.41-1.60
(m, 2H), 2.99 (brs, 1H), 3.40 (s, 3H), 3.66-3.82 (m, 3H), 4.65 (d, 1H,
J ) 6.9 Hz), 4.69 (d, 1H, J ) 6.9 Hz); 13C NMR δ 13.9, 22.4, 25.0,
29.3, 31.6, 34.5, 36.6, 55.5, 59.4, 76.0, 95.6. Anal. Calcd for
C11H24O3: C, 64.67; H, 11.84. Found: C, 64.59; H, 11.82.
1-Bromo-(3R)-3-(methoxymethoxy)nonane (34): To a solution of
33 (869.8 mg, 4.26 mmol) in dichloromethane (5.0 mL) was quickly
added a solution of carbon tetrabromide (2.8 g, 8.51 mmol) in
dichloromethane (3.0 mL) and triphenylphosphine (2.2 g, 8.51 mmol)
in dichloromethane (3.0 mL) at 0 °C. After stirring for 30 min, the
solvent was removed. The residue was then diluted with ether, and
the solids were filtered off. The filtrate was concentrated under reduced
pressure, and the residue was purified by column chromatography on
silica gel (hexane/ethyl acetate ) 20/1) to give 34 (1.05 g, 92%) as a
colorless oil. [R]D22 -20.9 (c ) 0.40, C6H6); IR (neat) 1039.4, 2929.3
1
cm-1; H NMR δ 0.88 (t, 3H, J ) 6.9 Hz), 1.29 (s, 8H), 1.42-1.61
(m, 2H), 2.00-2.08 (m, 2H), 3.39 (s, 3H), 3.50 (t, 2H, J ) 6.9 Hz),
3.67-3.76 (m, 2H), 4.65 (d, 1H J ) 6.9 Hz), 4.69 (d, 1H, J ) 6.9
Hz); 13C NMR δ 14.1, 22.6, 25.0, 29.4, 30.1, 31.8, 34.2, 37.8, 55.7,
75.7, 95.7. Anal. Calcd for C11H23BrO2: C, 49.45; H, 8.68; Br, 29.90.
Found: C, 49.62; H, 8.49; Br, 29.68.
1-Benzyloxy-(7R)-7-(methoxymethoxy)-3-tridecyne (35): To a
solution of 4-benzyloxy-1-butyne (818.4 mg, 5.11 mmol) in THF (8.0
mL) was added n-BuLi (1.6 M solution in hexane, 4.72 mmol) dropwise
over 5 min. The solution was stirred for 15 min, and a mixture of 34
(1.05 g, 3.93 mmol) in THF (6.5 mL) and HMPA (3.2 mL) was added
dropwise. After having been stirred for 10 min at -78 °C, the solution
was warmed to 0 °C and stirred for further 4 h. The reaction was
quenched with water, and the aqueous layer was extracted with ether.
The ethereal extract was washed with water and brine, dried over
sodium sulfate, and concentrated under reduced pressure. The residue
was purified by column chromatography on silica gel (hexane/ethyl
24
as a colorless oil. [R]25 -18.0 (c ) 1.15, C6H6); IR (neat) 1683.6,
acetate ) 30/1) to give 35 (1.13 g, 83%) as a colorless oil. [R]D
D
1
2927.4, 3378.7, 3475.1 cm-1; H NMR δ 0.88 (t, 3H, J ) 6.6 Hz),
-9.0 (c ) 0.91, C6H6); IR (neat) 2927.4 cm-1; 1H NMR δ 0.88 (t, 3H,
J ) 5.9 Hz), 1.28 (s, 8H), 1.40-1.49 (m, 2H), 1.68 (dt, 2H, J ) 6.9,
13.0 Hz), 2.20-2.27 (m, 2H), 3.37 (s, 3H), 3.55 (t, 2H, J ) 7.1 Hz),
3.61-3.67 (m, 1H), 4.54 (s, 2H), 4.65 (s, 2H), 7.25-7.35 (m, 5H);
13C NMR δ 14.1, 14.9, 20.1, 22.6, 25.1, 29.4, 31.8, 33.6, 34.1, 55.5,
68.8, 72.8, 76.3, 76.8, 80.9, 95.5, 127.6, 128.3, 138.1. Anal. Calcd
for C22H34O3: C, 76.26; H, 9.89. Found: C, 76.41; H, 9.95.
1.24-1.56 (m, 13H), 2.61-2.81 (m, 3H), 2.91 (q, 2H, J ) 7.5 Hz),
4.01-4.08 (m, 1H); 13C NMR δ 14.0, 14.6, 22.5, 23.3, 25.3, 29.1, 31.7,
36.5, 50.6, 68.6, 199.6. Anal. Calcd for C11H22O2S: C, 60.73; H,
10.09; S, 14.46. Found: C, 60.51; H, 10.16; S, 14.68. Enantiomeric
excess was determined by HPLC analysis after acetylation of 14. HPLC
(Daicel Chiralcel AS, hexane/i-PrOH ) 100/1, flow rate ) 1.0 mL/
min): tR ) 3.6 min (3S), tR ) 7.2 min (3R).
(7R)-7-(Methoxymethoxy)-1-tridecanol (36): To a solution of 35
(1.13 g, 3.26 mmol) in ethanol (16 mL) was added a catalytic amount
of 10% palladium-carbon under argon. The solution was stirred under
H2 at 1 atm for 20 h. Palladium-carbon was then filtered off, and the
filtrate was concentrated under reduced pressure. The residue was
purified by column chromatography on silica gel (hexane/ethyl acetate
Ethyl (3R)-3-(methoxymethoxy)nonanethioate (32): To a solution
of 14 (94% ee, 950.0 mg, 4.35 mmol) in dichloromethane (18 mL)
was added a solution of diisopropylethylamine (1.7 g, 13.1 mmol) in
dichloromethane (11 mL) and methoxymethyl chloride (1.1 g, 13.1
mmol) in dichloromethane (11 mL) at 0 °C. The solution was warmed
to room temperature and stirred for 10 h. The reaction was quenched
with saturated aqueous NaHCO3 solution and the aqueous layer was
extracted with dichloromethane. The extract was dried over sodium
sulfate and concentrated under reduced pressure. The residue was
purified by column chromatography on silica gel (hexane/ethyl acetate
) 9/1) to give 32 (1.14 g, 100%) as a colorless oil. [R]28D -0.3 (c )
0.54, C6H6); IR (neat) 1689.3, 2927.4 cm-1; 1H NMR δ 0.88 (t, 3H, J
) 5.8 Hz), 1.01-1.46 (m, 11H), 1.48-1.58 (m, 2H), 2.67 (dd, 1H, J
) 5.6, 15.0 Hz), 2.83 (dd, 1H J ) 7.3, 15.0 Hz), 2.89 (q, 2H, J ) 7.4
Hz), 3.35 (s, 3H), 3.99-4.08 (m, 1H), 4.63 (d, 1H, J ) 7.3 Hz), 4.66
(d, 1H, J ) 7.3 Hz); 13C NMR δ 14.0, 14.7, 22.5, 23.4, 25.0, 29.2,
31.7, 34.7, 49.3, 55.6, 74.6, 95.8, 197.4. Anal. Calcd for C13H26O3S:
C, 59.50; H, 9.99; S, 12.22. Found: C, 59.61; H, 10.05; S, 12.09.
(3R)-3-(Methoxymethoxy)-1-nonanol (33): To a suspension of
lithium aluminum hydride (496.5 mg, 13.1 mmol) in THF (9 mL) was
slowly added a solution of 32 (1.14 g, 4.35 mmol) in THF (16 mL) at
0 °C. The mixture was warmed to room temperature and stirred for
1.5 h. The mixture was then cooled to 0 °C and quenched with
saturated aqueous sodium sulfate solution. After adding of 1 N HCl
25
) 6/1) to give 36 (815.3 mg, 96%) as a colorless oil. [R]D -0.1 (c
) 1.31, C6H6); IR (neat) 2931.3, 3378.7 cm-1; 1H NMR δ 0.88 (t, 3H,
J ) 6.6 Hz), 1.11-1.57 (m, 20H), 1.70 (brs, 1H), 3.38 (s, 3H), 3.45-
3.54 (m, 1H), 3.64 (t, 2H, J ) 6.6 Hz), 4.65 (s, 2H); 13C NMR δ 14.1,
22.6, 25.2, 25.7, 29.5, 29.5, 31.8, 32.7, 34.2, 34.3, 55.4, 62.9, 77.4,
95.3. Anal. Calcd for C15H32O3: C, 69.18; H, 12.39. Found: C, 68.85;
H, 12.22.
1-Bromo-(7R)-7-methoxymethoxytridecane (12): To a solution of
35 (815.3 mg, 3.13 mmol) in dichloromethane (6.0 mL) was quickly
added a solution of carbon tetrabromide (2.08 g, 6.26 mmol) in
dichloromethane (4.5 mL) and triphenylphosphine (1.64 g, 6.26 mmol)
in dichloromethane (4.5 mL) at 0 °C. After stirring for 30 min, the
solvent was removed under reduced pressure. The residue was then
diluted with ether, and the solids were filtered off. The filtrate was
concentrated under reduced pressure, and the residue was purified by
column chromatography on silica gel (hexane/ethyl acetate ) 20/1) to
26
give 12 (890.7 mg, 88%) as a colorless oil. [R]D -0.06 (c ) 0.97,
1
C6H6); IR (neat) 2931.3 cm-1; H NMR δ 0.88 (t, 3H, J ) 6.4 Hz),
1.18-1.60 (m, 18H), 1.86 (dt, 2H, J ) 6.6, 14.4 Hz), 3.38 (s, 3H),

916 J. Am. Chem. Soc., Vol. 120, No. 5, 1998
Kobayashi et al.
3.41 (t, 2H, J ) 5.6, 11.3 Hz), 4.65 (s, 2H); 13C NMR δ 14.1, 22.6,
25.1, 25.2, 28.1, 28.9, 29.5, 31.8, 32.7, 33.9, 34.1, 34.3, 55.5, 77.5,
95.3. Anal. Calcd for C15H31BrO2: C, 55.72; H, 9.66; Br, 24.71.
Found: C, 55.96; H, 9.51; Br, 23.47.
°C. The mixture was warmed to room temperature and stirred for 10
min. The mixture was refluxed for 1 h and then cooled to 0 °C. The
reaction was quenched with saturated aqueous potassium sodium
tartarate solution. After the suspension was stirred vigorously, the
aqueous layer was extracted with ether. The ethereal extract was
washed with water and brine, dried over sodium sulfate, and concen-
trated under reduced pressure to give a yellow oil. To a solution of
the yellow oil in DMF (12 mL) was added a solution of imidazole
(501.4 mg, 7.36 mmol) in DMF (6.0 mL) and tert-butyldimethylsilyl
chloride (1.11 g, 7.36 mmol) in DMF (6.0 mL) at 0 °C. After the
solution was stirred for 10 h at room temperature, the reaction was
quenched with water, and the aqueous layer was extracted with ether.
The ethereal extract was washed with water and brine, dried over
sodium sulfate, and concentrated under reduced pressure. The residue
was purified by column chromatography on silica gel (hexane/ethyl
acetate ) 30/1) to give 40 (1.56 g, 93%, two steps) as a yellow oil.
[R]D26 -7.5 (c ) 0.97, C6H6); IR (neat) 1251.6, 2919.7 cm-1; 1H NMR
δ -0.06 (s, 6H), 0.00 (s, 6H), 0.79-0.85 (m, 21H), 1.18-1.35 (m,
18H), 1.83 (m, 2H), 3.04 (dd, 1H, J ) 6.3, 9.6 Hz), 3.25 (d, 1H, J )
9.6 Hz), 3.47 (m, 1H), 3.56-3.59 (m, 1H), 3.70 (s, 3H), 4.22 (t, 1H,
J ) 5.8 Hz), 4.68 (d, 1H, J ) 11.9 Hz), 4.75 (d, 1H, J ) 11.9 Hz),
5.28 (dd, 1H, J ) 6.1, 15.3 Hz), 5.46 (m, 1H), 6.74 (d, 2H, J ) 8.6
Hz), 7.11-7.44 (m, 19H); 13C NMR δ -4.8, -4.4, -4.4, 14.1, 18.2,
22.6, 25.3, 25.9, 26.0, 29.1, 29.2, 29.6, 29.7, 31.9, 32.1, 37.2, 55.1,
63.9, 72.3, 73.1, 73.8, 82.7, 86.2, 112.9, 126.4, 127.3, 127.7, 127.7,
128.2, 128.3, 128.5, 129.3, 130.4, 132.0, 135.9, 139.2, 144.7, 158.3;
FABHRMS calcd for C57H86O5Si2 (M + Na) 929.5911, found 929.5905.
Anal. Calcd for C57H86O5Si2: C, 75.44; H, 9.55. Found: C, 75.58;
H, 9.49.
(2S,3S,9′R)-3-Benzyloxy-2-(9′-(methoxymethoxy)pentadec-1-ynyl)-
2,2-dimethyl-1,3-dioxane (37): To a solution of 13 (646.4 mg, 2.62
mmol) in THF (15.0 mL) at -78 °C was added n-BuLi (1.6 M solution
in hexane, 2.62 mmol) dropwise over 5 min. The mixture was stirred
for 15 min, and a mixture of 12 (890.7 mg, 2.75 mmol) in THF (4.0
mL) and HMPA (1.9 mL) was added dropwise. After stirring for 10
min at -78 °C, the mixture was warmed to 0 °C and stirred for a
further 10 h. The reaction was quenched with water, and the aqueous
layer was extracted with ether. The ethereal extract was washed with
water and brine, dried over sodium sulfate, and concentrated under
reduced pressure. The residue was purified by column chromatography
on silica gel (hexane/ethyl acetate ) 9/1) to give 37 (1.10 g, 86%) as
a colorless oil. [R]D24 +4.4 (c ) 1.06, C6H6); IR (neat) 1375.0, 1457.9,
2242.8, 2856.1 cm-1; 1H NMR δ 0.88 (t, 3H, J ) 6.4 Hz), 1.28-1.60
(m, 26H), 2.27 (dt, 2H, J ) 2.0, 7.1 Hz), 3.33-3.39 (m, 4H), 3.50 (t,
1H, J ) 5.6 Hz), 3.82-3.94 (m, 2H), 4.64 (s, 2H), 4.77-4.78 (m,
3H), 7.24-7.44 (m, 5H); 13C NMR δ 14.0, 18.9, 20.3, 22.5, 25.05,
25.14, 27.8, 28.3, 28.9, 29.3, 29.4, 31.7, 34.2, 55.3, 61.7, 63.8, 71.1,
71.7, 76.1, 77.5, 87.3, 95.2, 99.3, 127.5, 127.8, 128.1, 138.1; FAB-
HRMS calcd for C30H48O5 (M + Na) 511.3399, found 511.3396. Anal.
Calcd for C30H48O5: C, 73.73; H, 9.90. Found: C, 73.67; H, 9.95.
(2S,3S,12R)-2-Benzyloxyoctadec-4-yne-1,3,12-triol (38): To a solu-
tion of 37 (1.10 g, 2.26 mmol) in methanol (35 mL) was added
concentrated HCl (0.5 mL), and the mixture was stirred for 30 min at
60 °C. The mixture was cooled to room temperature, then diluted with
water (60 mL), and cooled to 0 °C. The mixture was neutralized with
potassium carbonate, and the aqueous layer was extracted with ether.
The ethereal extract was washed with saturated aqueous NaHCO3
solution, water, and brine, dried over sodium sulfate, and concentrated
under reduced pressure. The residue was purified by column chro-
matography on silica gel (hexane/ethyl acetate ) 2/1) to give 38 (876.4
(2R,3S,14R)-2-Benzyloxy-3,14-bis(tert-butyldimethylsiloxy)octa-
dec-4-ene-1-ol (41): To a solution of 40 (1.56 g, 1.72 mmol) in ether
(120 mL) was added 98% formic acid (60 mL). The mixture was stirred
for 30 min at 0 °C and then diluted with water (150 mL). The solution
was neutralized with potassium carbonate, and the aqueous layer was
extracted with ether. The ethereal extract was washed with water and
brine, dried over sodium sulfate, and concentrated under reduced
pressure. The residue was purified by column chromatography on silica
gel (hexane/ethyl acetate ) 20/1) to give 41 (927.1 mg, 85%) as a
colorless oil. [R]D27 +16.5 (c ) 1.81, C6H6); IR (neat) 1253.5, 2856.1,
24
mg, 96%) as a colorless oil. [R]D +0.6 (c ) 5.25, C6H6); IR (neat)
1
2337.3, 2927.4, 3371.0 cm-1; H NMR δ 0.80 (t, 3H, J ) 6.9 Hz),
1.20-1.44 (m, 20H), 1.87 (brs, 1H), 2.14 (t, 2H, J ) 5.9 Hz), 2.61
(brs, 1H), 3.08 (brs, 1H), 3.47-3.52 (m, 2H), 3.65 (dd, 1H, J ) 5.0,
11.9 Hz), 3.76 (dd, 1H, J ) 4.6, 11.5 Hz), 4.40 (m, 1H), 4.63 (d, 1H,
J ) 11.5 Hz), 4.71 (d, 1H, J ) 11.5 Hz), 7.20-7.29 (m, 5H); 13C
NMR δ 14.0, 18.6, 22.5, 25.3, 25.5, 28.2, 28.6, 28.9, 29.3, 31.7, 37.1,
37.3, 61.6, 62.9, 71.8, 73.3, 78.2, 82.0, 87.0, 127.9, 128.4, 137.8;
FABHRMS calcd for C25H40O4 (M + Na) 427.2824, found 427.2833.
Anal. Calcd for C30H48O5: C, 74.22; H, 9.97. Found: C, 74.38; H,
9.88.
(2S,3S,12R)-2-Benzyloxy-1-(4-methoxyphenyldiphenylmethoxy)-
octadec-4-yne-3,12-diol (39): To a solution of 38 (876.4 mg, 2.17
mmol) in dichloromethane (12 mL) was added a solution of triethyl-
amine (438.3 mg, 4.3 mmol) in dichloromethane (6.0 mL), and a
solution 4-methoxytrityl chloride (1.2 g, 4.3 mmol) in dichloromethane
(6.0 mL) at 0 °C. After a catalytic amount of N,N-(dimethylamino)-
pyridine was added, the mixture was stirred for 1 h. The reaction was
quenched with water, and the aqueous layer was extracted with
dichloromethane. The extract was dried over sodium sulfate and
concentrated under reduced pressure. The residue was purified by
1
2931.3 cm-1; H NMR δ 0.03 (s, 6H), 0.04 (s, 6H), 0.86 (t, 3H, J )
6.8 Hz), 0.886 (s, 9H), 0.888 (s, 9H), 1.27-1.39 (m, 20H), 2.04 (dt,
2H, J ) 6.8, 13.4 Hz), 2.18 (brs, 1H), 3.45-3.53 (m, 2H), 3.59 (dt,
1H, J ) 5.6, 11.5 Hz), 3.75 (dd, 1H, J ) 4.6, 11.2 Hz), 4.29 (d, 1H,
J ) 5.9 Hz), 4.62 (d, 1H, J ) 11.6 Hz), 4.75 (d, 1H, J ) 11.6 Hz),
5.49 (dd, 1H, J ) 6.3, 15.5 Hz), 5.67 (dt, 1H, J ) 6.6, 15.5 Hz), 7.16-
7.40 (m, 5H); 13C NMR δ -4.9, -4.5, -4.4, 14.1, 18.1, 22.6, 25.3,
25.8, 25.9, 29.2, 29.2, 29.5, 29.7, 31.9, 32.3, 37.1, 61.9, 72.4, 73.0,
74.0, 81.9, 127.8, 127.8, 128.5, 133.1, 138.5; FABHRMS calcd for
C37H70O4Si2 (M + Na) 657.4711, found 657.4714. Anal. Calcd for
C37H70O4Si2: C, 69.97; H, 11.11. Found: C, 69.82; H, 10.97.
(2R,3S,12R)-2-Benzyloxy-3,12-bis(tert-butyldimethyisiloxy)octa-
dec-4-enal (10): To a solution of oxalyl chloride (60.9 mg, 0.48 mmol)
in dichloromethane (1.5 mL) was added a solution of dimethyl sulfoxide
(48.8 mg, 0.62 mmol) in dichloromethane (1.1 mL) dropwise over 15
min at -78 °C. A solution of 41 (151.9 mg, 0.24 mmol) in
dichloromethane (1.7 mL) was added, and the mixture was stirred for
10 min at -78 °C and for 1 h at -50 °C. Triethylamine (176.0 mg,
1.67 mmol) was added, and the mixture warmed to 0 °C and stirred
for 20 min. The reaction was quenched with saturated aqueous NH4-
Cl solution, and the aqueous layer was extracted with dichloromethane.
The extract was washed with water and brine, dried over sodium sulfate,
and concentrated under reduced pressure. The residue was purified
by column chromatography on silica gel (hexane/ethyl acetate ) 20/
1) to give 10 (151.4 mg, quant.) as a colorless oil. 1H NMR δ 0.04 (s,
6H), 0.06 (s, 6H), 0.90-0.91 (m, 21H), 1.30-1.41 (m, 20H), 2.01-
2.06 (m, 2H), 3.64 (t, 1H, J ) 5.3 Hz), 3.76 (dd, 1H, J ) 1.5, 5.0 Hz),
4.43 (t, 1H, J ) 5.6 Hz), 4.59 (d, 1H, J ) 12.2 Hz), 4.71 (d, 1H, J )
12.2 Hz), 5.57 (dd, 1H, J ) 6.6, 15.5 Hz), 5.70 (dt, J ) 6.3, 15.5 Hz),
7.28-7.37 (m, 5H), 9.69 (d, 1H, J ) 1.5 Hz); 13C NMR δ -5.0, -4.4,
14.1, 18.1, 22.6, 25.3, 25.7, 25.9, 29.0, 29.1, 29.5, 29.7, 31.9, 32.1,
column chromatography on silica gel (hexane/ethyl acetate ) 2/1) to
25
give 39 (1.25 g, 85%) as a yellow oil. [R]
+8.6 (c ) 1.0, C6H6);
D
IR (neat) 2233.2, 2923.6, 3423.0 cm-1; H NMR δ 0.88 (t, 3H, J )
6.4 Hz), 1.28-1.40 (m, 20H), 2.12 (m, 2H), 2.87 (brs, 1H), 3.32 (dd,
1H, J ) 5.0, 9.6 Hz), 3.45 (dd, 1H, J ) 4.3, 10.2 Hz), 3.54 (brs, 1H),
3.63 (m, 1H), 3.76 (s, 3H), 4.55 (m, 1H), 4.61 (d, 1H, J ) 12.2 Hz),
4.73 (d, 1H, J ) 11.6 Hz), 6.79-7.47 (m, 19H); 13C NMR δ 14.0,
18.6, 22.5, 25.4, 25.4, 25.5, 28.3, 28.8, 29.0, 29.3, 31.8, 37.3, 37.4,
55.1, 62.8, 62.9, 71.8, 73.1, 78.2, 81.3, 86.4, 86.5, 113.0, 126.8, 127.7,
127.9, 128.2, 128.3, 130.3, 135.4, 137.9, 144.2, 158.4. Anal. Calcd
for C45H56O5: C, 79.84; H, 8.34. Found: C, 79.98; H, 8.33.
1
(2S,3S,12R)-2-Benzyloxy-3,12-bis(tert-butyldimethylsiloxy)-1-(4-
methoxyphenyldiphenylmethoxy)-4-octadecene (40): To a suspension
of lithium aluminum hydride (244.6 mg, 6.44 mmol) in THF (40 mL)
was added a solution of 39 (1.25 g, 1.84 mmol) in THF (40 mL) at 0

Syntheses of Antifungal Sphingofungins
J. Am. Chem. Soc., Vol. 120, No. 5, 1998 917
37.1, 72.3, 72.8, 73.8, 86.2, 127.9, 128.1, 128.4, 133.6, 137.4, 202.6;
FABHRMS calcd for C37H68O4Si2 (M + Na) 655.4553, found 655.4559.
(2S,3S,4S,5S,14R), tR ) 21.6 min (2S,3R,4S,5S,14R), tR ) 28.0 min
(2R,3R,4S,5S,14R).
(2S,3R,4R,5S,14R)-4-Benzyloxy-2-(tert-butoxycarbonylamino)-
3,5,14-trihydroxyeicos-6-enoic acid (43c): To a solution of 42c (60.9
mg, 0.073 mmol) in THF (3.0 mL) and water (1.0 mL) was added
lithium hydroxide (12.2 mg, 0.29 mmol) at 0 °C. The mixture was
stirred for 10 h and was neutralized with a resin (IRC-76). The resin
was filtered off, and the filtrate was concentrated under reduced pressure
to give a colorless oil of a carboxylic acid. To a solution of the
carboxylic acid in THF (1.2 mL) was added tetrabutylammonium
fluoride 1.0 N solution in THF (0.29 mmol) at room temperature. After
stirring for 48 h at 50 °C, the reaction was quenched with phosphate
buffer solution (pH ) 7). The aqueous layer was extracted with ether,
and the ethereal extract was washed with 10% aqueous citric acid
solution, saturated aqueous NaHCO3 solution, and brine, dried over
sodium sulfate, and concentrated under reduced pressure. The residue
was purified by column chromatography on silica gel (hexane/ethyl
acetate ) 10/1) to give 43c (40.4 mg, 96%, two steps) as a colorless
Ethyl (2S,3R,4S,5S,14R)-4-benzyloxy-2-(tert-butoxycarbonylamino)-
5,14-bis(tert-butyldimethylsiloxy)-3-hydroxyeicos-6-enoate (42c): To
a solution of diisopropylamine (41.3 mg, 0.41 mmol) in THF (1.9 mL)
was added n-BuLi (1.6 M solution in hexane, 0.38 mmol) dropwise at
0 °C. The mixture was stirred for 10 min and cooled to -78 °C. A
solution of 11 (94.3 mg, 0.38 mmol) in THF (1.8 mL) was then added,
and, after stirring for 30 min, a solution of zinc chloride (51.8 mg,
0.38 mmol) in THF (1.0 mL) was added. The mixture was warmed to
0 °C and stirred for a further 30 min. After the mixture was cooled to
-78 °C, a solution of 10 (152.0 mg, 0.24 mmol) in THF (1.7 mL) was
added. The mixture was stirred for 30 min at -78 °C and for 30 min
at 0 °C. The reaction was quenched with saturated aqueous NH4Cl
solution, and the aqueous layer was extracted with ether. The ethereal
extract was washed with water and brine, dried over sodium sulfate,
and concentrated under reduced pressure. The residue was purified
by column chromatography on silica gel to give an aldol adduct (163.8
mg, 93%). To a solution of the aldol adduct (163.8 mg, 0.22 mmol)
in dichloromethane (1.0 mL) was added a solution of di-tert-butyldi-
carbonate (72.8 mg, 0.33 mmol) in dichloromethane (1 mL) at room
temperature. After stirring for 10 h, the reaction was quenched with
water, and the aqueous layer was extracted with dichloromethane. The
extract was dried over sodium sulfate and concentrated under reduced
pressure. The residue was purified by column chromatography on silica
gel (hexane/ethyl acetate ) 20/1) to give 42a-d (113.5 mg, 61%) as
a colorless oil. Diastereomers 42a-d could be separated by column
chromatography on silica gel (hexane/ethyl acetate ) 20/1), and the
diastereomer ratio was determined by HPLC analyses. 42a: 1H NMR
δ 0.003 (s, 3H), 0.01 (s, 3H), 0.03 (s, 9H), 0.86-0.88 (m, 21H), 1.23-
1.39 (m, 23H), 1.43 (s, 9H), 2.01-2.06 (m, 2H), 3.59-3.66 (m, 2H),
4.02 (d, 1H, J ) 8.9 Hz), 4.10 (brs, 1H), 4.16 (dq, 2H, J ) 2.3, 7.3
Hz), 4.40 (m, 1H), 4.57 (d, 1H, J ) 8.9 Hz), 4.64 (d, 1H, J ) 11.6
Hz), 4.70 (d, 1H, J ) 11.6 Hz), 5.46 (d, 1H, J ) 8.6 Hz), 5.55-5.74
(m, 2H), 7.28-7.36 (m, 5H); 13C NMR δ -5.3, -4.7, -4.4, 14.1, 14.3,
18.0, 18.2, 22.6, 25.3, 25.7, 25.9, 28.3, 29.2, 29.3, 29.5, 29.7, 31.9,
32.3, 37.2, 53.4, 55.7, 61.2, 72.3, 72.9, 73.3, 73.7, 78.9, 79.7, 127.0,
127.8, 128.4, 133.6, 138.1, 155.8, 170.4; FABHRMS calcd for C46H85-
NO8Si2 (M + Na) 858.5712, found 858.5706. 42b: 1H NMR δ -0.02
(s, 6H), 0.03 (s, 6H), 0.86-0.88 (m, 21H), 1.11-1.43 (m, 23H), 1.50
(s, 9H), 2.06-2.08 (m, 2H), 3.35 (dd, 1H, J ) 4.0, 9.6 Hz), 3.55-
3.69 (m, 1H), 4.12-4.30 (m, 4H), 4.33 (m, 1H), 4.56-4.69 (m, 2H),
5.43 (d, 1H, J ) 10.2 Hz), 5.52-5.73 (m, 2H), 7.33-7.36 (m, 5H);
13C NMR δ -5.4, -4.8, -4.4, 14.1, 14.2, 18.0, 18.1, 22.6, 25.3, 25.7,
25.9, 28.4, 29.2, 29.5, 29.7, 31.9, 32.3, 37.2, 53.4, 54.6, 61.3, 72.3,
72.7, 73.5, 73.6, 77.2, 79.6, 126.4, 128.1, 128.5, 128.7, 134.0, 137.8,
156.1, 171.7; FABHRMS calcd for C46H85NO8Si2 (M + Na) 858.5712,
1
oil. 43c: H NMR (CD3OD) δ 0.90 (t, 3H, J ) 6.4 Hz), 1.30-1.42
(m, 29H), 2.01-2.04 (m, 2H), 3.48 (brs, 1H), 3.60 (brs, 1H), 3.95 (dd,
1H, J ) 3.3, 7.3 Hz), 4.27 (d, 1H, J ) 7.6 Hz), 4.37 (t, 1H, J ) 5.3
Hz), 4.69 (d, 1H, J ) 10.8 Hz), 4.77 (d, 1H, J ) 10.8 Hz), 5.58 (dd,
1H, J ) 6.6, 15.2 Hz), 5.75 (dt, 1H, J ) 6.3, 15.2 Hz), 7.22-7.46 (m,
5H); FABHRMS calcd for C32H53NO8 (M + Na) 602.3668, found
602.3663. Similarly, 42a, 42b, and 42d were prepared. 43a: 1H NMR
(CD3OD) δ 0.90 (t, 3H, J ) 6.9 Hz), 1.30-1.39 (m, 29H), 1.98 (brs,
2H), 3.48 (brs, 2H), 3.64 (brs, 1H), 4.14 (brs, 1H), 4.34 (brs, 1H), 4.45-
4.60 (m, 2H), 5.52-5.75 (m, 2H), 7.27-7.41 (m, 5H); FABHRMS
1
calcd for C32H53NO8 (M + Na) 602.3668, found 602.3680. 43b: H
NMR (CD3OD) δ 0.89 (t, 3H, J ) 6.6 Hz), 1.29-1.45 (m, 29H), 2.02-
2.07 (m, 2H), 3.38 (brs, 1H), 3.42 (brs, 1H), 3.47 (brs, 1H), 4.32 (d,
1H, J ) 9.2 Hz), 4.41 (t, 1H, J ) 5.4 Hz), 4.54 (d, 1H, J ) 12.2 Hz),
4.58 (d, 1H, J ) 10.2 Hz), 5.62 (dt, 1H, J ) 5.6, 9.9 Hz), 5.72 (dd,
1H, J ) 5.6 Hz), 7.22-7.46 (m, 5H); FABHRMS calcd for C32H53-
1
NO8 (M + Na) 602.3668, found 602.3662. 43d: H NMR (CD3OD)
δ 0.89 (t, 3H, J ) 6.9 Hz), 1.29-1.43 (m, 29H), 1.99-2.01 (m, 2H),
3.37 (d, 1H, J ) 4.3 Hz), 3.48 (brs, 1H), 4.23 (brs, 1H), 4.33-4.48
(m, 2H), 4.63 (d, 1H, J ) 10.9 Hz), 4.78 (d, 1H, J ) 11.2 Hz), 5.54
(dd, 1H, J ) 6.4, 15.3 Hz), 5.69 (dt, 1H, J ) 6.3, 15.2 Hz), 7.22-7.46
(m, 5H); FABHRMS calcd for C32H53NO8 (M + Na) 602.3668, found
602.3680.
(2S,3S,4R,5S,14R)-2-Amino-4-benzyloxy-3,5,14-trihydroxyeicos-
6-enoic acid (44c): To a solution of 43c (23.0 mg, 0.040 mmol) in
dichloromethane (1.5 mL) was added trifluoroacetic acid (1.5 mL) at
0 °C. After stirring for 45 min, the solution was concentrated under
reduced pressure, and the residue was diluted with THF (2.0 mL) and
water (1.0 mL). NaOH aqueous (1 N, 0.2 mL) was added, and the
mixture was stirred for 30 min at 0 °C and neutralized with a resin
(IRC-76). The resin was filtered off, and the filtrate was diluted with
ether (5.0 mL) and washed with water and brine. The combined organic
layer was dried over sodium sulfate and concentrated under reduced
pressure. The residue was purified by column chromatography on silica
gel (chloroform/methanol ) 6/1) to give 44c (20.0 g, 100%) as a white
solid.
(2S,3R,4R,5S,14R)-2-Amino-3,4,5,14-tetrahydroxyeicos-6-enoic acid
(sphingofungin B) (4): To a dark blue solution of sodium-ammonia
prepared from excess sodium and liquid ammonia (10 mL) was added
a solution of 44c (20.0 mg, 0.040 mmol) in THF (1.5 mL) at -78 °C.
The solution was warmed to -50 °C and was stirred for 1 h. The
reaction was quenched with ammonium chloride (254.5 mg, 4.8 mmol).
The cooling bath was removed, and after all ammonia was evaporated,
the mixture was diluted with water, and the aqueous layer extracted
with n-butanol. The extract was washed with water and was concen-
trated under reduced pressure. The residue was purified by Sephadex
(LH-20, H2O to H2O/methanol ) 1/2) and reverse phase column
chromatography (Wakogel, LP-60-C18, H2O to H2O/methanol ) 1/2)
to give 4 (8.2 mg, 53%) as a white solid. 4: 1H NMR (CD3OD) δ
0.89 (t, 3H, J ) 6.4 Hz), 1.18-1.60 (m, 20H), 1.98-2.06 (m, 2H),
3.49 (brs, 1H), 3.60 (d, 1H, J ) 6.9 Hz), 3.77 (d, 1H, J ) 3.6 Hz),
4.06-4.10 (m, 2H), 5.47 (dd, 1H, J ) 7.3, 15.2 Hz), 5.77 (dt, 1H, J )
6.6, 15.2 Hz); 13C NMR δ 14.4, 23.7, 26.79, 26.82, 30.2, 30.4, 30.6,
1
found 858.5713. 42c: H NMR δ 0.01 (s, 3H), 0.02 (s, 3H), 0.03 (s,
6H), 0.88-0.95 (m, 21H), 1.21-1.42 (m, 32H), 1.99-2.04 (m, 2H),
2.66 (d, 1H, J ) 8.9 Hz), 3.43 (d, 1H, J ) 5.0 Hz), 3.61 (t, 1H, J )
5.5), 3.96 (t, 1H, J ) 7.3 Hz), 4.11 (q, 2H, J ) 7.0 Hz), 4.27-4.41
(m, 2H), 4.63 (d, 1H, J ) 10.7 Hz), 4.89 (d, 1H, J ) 10.7 Hz), 5.31
(d, 1H, J ) 8.9 Hz), 5.50 (dd, 1H, J ) 6.9, 15.5 Hz), 5.66 (dt, J ) 6.3,
15.5 Hz), 7.29-7.46 (m, 5H); 13C NMR δ -4.8, -4.4, -4.2, 14.1,
18.07, 18.11, 22.6, 25.3, 25.86, 25.91, 28.2, 29.1, 29.2, 29.5, 29.7, 31.9,
32.3, 37.1, 56.8, 61.2, 70.0, 72.3, 73.9, 74.1, 79.8, 80.6, 127.8, 128.2,
128.4, 129.2, 133.9, 138.0, 155.3, 171.4; FABHRMS calcd for C46H85-
NO8Si2 (M + Na) 858.5712, found 858.5704. 42d: 1H NMR δ 0.03
(s, 9H), 0.04 (s, 3H), 0.86-0.88 (m, 21H), 1.20-1.42 (m, 23H), 1.44
(s, 9H), 1.99-2.04 (m, 2H), 2.76 (d, 1H, J ) 5.0 Hz), 3.42 (t, 1H, J
) 5.0 Hz), 3.60 (t, 1H, J ) 5.4 Hz), 4.27 (q, 2H, J ) 7.3 Hz), 4.24 (d,
1H, J ) 2.6 Hz), 4.29-4.39 (m, 2H), 4.57 (d, 1H, J ) 11.1 Hz), 4.80
(d, 1H, J ) 11.1 Hz), 5.33 (d, 1H, J ) 8.9 Hz), 5.52 (dd, 1H, J ) 6.9,
15.5 Hz), 5.67 (dt, 1H, J ) 6.3, 15.5 Hz), 7.29-7.35 (m, 5H); 13C
NMR δ -4.8, -4.4, -4.1, 14.1, 18.1, 22.6, 25.3, 25.9, 25.9, 28.3,
29.1, 29.3, 29.5, 29.7, 31.9, 32.3, 37.2, 56.4, 61.3, 69.7, 72.4, 73.6,
74.1, 79.7, 81.6, 127.9, 128.4, 129.0, 133.7, 137.9, 155.9, 171.0;
FABHRMS calcd for C46H85NO8Si2 (M + Na) 858.5712, found
858.5728. HPLC (Shodex SIL-5B, hexane/ethyl acetate ) 10/1, flow
rate ) 1.0 mL/min): tR ) 11.7 min (2R,3S,4S,5S,14R), tR ) 14.4 min

918 J. Am. Chem. Soc., Vol. 120, No. 5, 1998
Kobayashi et al.
30.7, 33.1, 33.5, 38.5, 60.8, 69.4, 72.5, 75.2, 76.0, 130.2, 135.5, 172.4;
was dried over sodium sulfate and concentrated under reduced pressure.
The residue was purified by column chromatography on silica gel
(hexane/ethyl acetate ) 50/1) to give 54 (2.08 g, 97%) as a colorless
FABHRMS calcd for C20H39NO6 (M + H) 390.2856, found 390.2859.
Similary, other stereoisomers, 4a, 4b, and 4d, ware prepared. 4a: 13
C
1
NMR (CD3OD) δ 14.4, 23.7, 26.8, 30.3, 30.47, 30.56, 30.64, 30.8,
33.1, 38.5, 57.3, 72.5; FABHRMS calcd for C20H39NO6 (M + H)
390.2856, found 390.2868. 4b: 1H NMR (CD3OD) δ 0.89 (t, 3H, J )
6.9 Hz), 1.28-1.58 (m,20H), 2.06-2.08 (m, 2H),3.50 (m,2H), 3.92
(brs, 1H), 4.20-4.28 (m,2H), 5.62 (dd, 1H, J ) 6.6, 15.5 Hz), 5.77
(dt, 1H, J ) 6.3, 15.5 Hz); 13C NMR δ 14.4, 23.7, 26.8, 30.3, 30.6,
30.7, 33.1, 33.5, 38.5, 57.3, 70.3, 72.5, 73.2, 77.1, 131.2, 134.2, 173.3;
FABHRMS calcd for C20H39NO6 (M + H) 390.2856, found 390.2844.
4d: 13C NMR (CD3OD) δ 14.4, 23.7, 26.8, 30.2, 30.4, 30.6, 30.7, 33.1,
33.5, 38.4, 61.5, 70.0, 72.4, 74.2, 77.6, 130.2, 135.5, 173.0; FABHRMS
calcd for C20H39NO6 (M + H) 390.2856, found 390.2865. Stereoisomer
4e was prepared using ent-12. Stereoisomer 4f and 4 g were
synthesized using ent-13. 4e: 1H NMR (CD3OD) δ 0.89 (t, 3H, J )
6.4 Hz), 1.18-1.60 (m, 20H), 1.98-2.06 (m, 2H), 3.49 (brs, 1H), 3.60
(d, 1H, J ) 6.9 Hz), 3.77 (d, 1H, J ) 3.6 Hz), 4.06-4.10 (m, 2H),
5.47 (dd, 1H, J ) 7.3, 15.2 Hz), 5.77 (dt, 1H, J ) 6.6, 15.2 Hz); 13C
NMR δ 14.4, 23.7, 26.79, 26.82, 30.2, 30.4, 30.6, 30.7, 33.1, 33.5,
38.5, 60.8, 69.4, 72.5, 75.2, 76.0, 130.2, 135.5, 172.4; FABHRMS calcd
for C20H39NO6 (M + H) 390.2856, found 390.2846. (2R,3S,4S,5R,14RS)-
2-Amino-3,4,5,14-tetrahydroxyeicos-6-enoic acid (4f): 1H NMR
(CD3OD) δ 0.89 (t, 3H, J ) 6.4 Hz), 1.18-1.60 (m, 20H), 1.98-2.06
(m, 2H), 3.49 (brs, 1H), 3.60 (d, 1H, J ) 6.9 Hz), 3.77 (d, 1H, J ) 3.6
Hz), 4.06-4.10 (m, 2H), 5.47 (dd, 1H, J ) 7.3, 15.2 Hz), 5.77 (dt,
1H, J ) 6.6, 15.2 Hz); 13C NMR δ 14.4, 23.7, 26.79, 26.82, 30.2,
30.4, 30.6, 30.7, 33.1, 33.5, 38.5, 60.8, 69.4, 72.5, 75.2, 76.0, 130.2,
135.5, 172.4; FABHRMS calcd for C20H39NO6 (M + H) 390.2856,
found 390.2845. (2S,3R,4S,5R,14RS)-2-Amino-3,4,5,14-tetrahydroxy-
eicos-6-enoic acid (4 g): 13C NMR (CD3OD) δ 14.4, 23.7, 26.8, 30.3,
30.47, 30.56, 30.64, 30.8, 33.1, 38.5, 57.3, 72.5; FABHRMS calcd for
C20H39NO6 (M + H) 390.2856, found 390.2871.
oil. IR (neat) 1252.0, 2859.0, 2932.0 cm-1; H NMR δ 0.00 (s, 9H),
0.78 (t, 3H, J ) 6.4 Hz), 1.17-1.51 (m, 18H), 1.70-1.80 (m, 2H),
3.30 (t, 2H, J ) 6.8 Hz), 3.36-3.58 (m, 1H); 13C NMR δ 0.8, 14.4,
22.9, 25.8, 26.0, 28.5, 29.2, 30.0, 32.2, 33.1, 34.3, 37.6, 37.8, 72.9;
HRMS calcd for C16H35BrOSi (M+) 350.1641, found 350.1662.
(16S,17S)-17-Benzyloxy-16,18-dihydroxyoctadec-14-yn-7-one eth-
ylene acetal (59): To a solution of trimethylsilyl trifluoromethane-
sulfonate (17.2 mg, 0.08 mmol) in dichloromethane (3.0 mL) was added
a solution of 1,2-bis(trimethylsilyloxy)ethane (479.1 mg, 2.3 mmol) in
dichloromethane (2.3 mL) and 58 (622.9 mg, 1.55 mmol) in dichlo-
romethane (5.0 mL) at 0 °C. After the mixture was stirred for 1 h, the
reaction was quenched with pyridine (0.2 mL) and saturated aqueous
NaHCO3 solution. The aqueous layer was extracted with ether. The
ethereal extract was washed with water and brine, dried over sodium
sulfate, and concentrated under reduced pressure. The residue was
purified by column chromatography on silica gel (hexane/ethyl acetate
) 9/1) to give 59 (649.8 mg, 94%) as a colorless oil. 1H NMR δ 0.88
(t, 3H, J ) 6.3 Hz), 1.28-1.59 (m, 20H), 2.04 (br, 1H), 2.22(dt, 2H,
J ) 1.7, 7.0 Hz), 2.69 (br, 1H), 3.58 (dd, 1H, J ) 4.7, 10.3 Hz), 3.79
(ddd, 2H, J ) 4.6, 11.6, 27.8 Hz), 3.91 (s, 4H), 4.49 (d, 1H, J ) 5.6
Hz), 4.76 (dd, 2H, J ) 11.5, 20.1 Hz), 7.26-7.37 (m, 5H); 13C NMR
δ 14.0, 18.7, 22.6, 23.6, 23.8, 28.3, 28.8, 29.3, 29.5, 31.8, 37.0, 37.1,
61.7, 63.1, 64.8, 73.4, 78.1, 82.1, 87.4, 111.8, 127.9, 128.0, 128.5, 137.8;
FABHRMS calcd for C27H42O5 (M + Na) 469.2930, found 469.2933.
(1′S,4′S,16S,17S,18R)-17-Benzyloxy-16-(tert-butyldimethylsiloxy)-
18-(3′,6′-diethoxy-1′,4′-dimethyl-4′H-2,5-diazyl)-18-hydroxyoctadec-
14-ene-7-one (63): To a solution of 47 (81.4 mg, 0.41 mmol) in THF
(1.5 mL) was added n-BuLi (1.6 M solution in hexane, 0.41 mmol)
dropwise at -78 °C. The mixture was warmed to 0 °C and stirred for
15 min, and a solution of tin(II) chloride (77.9 mg, 0.41 mmol) in THF
(1.5 mL) was added. The mixture was stirred for a further 15 min,
and after the solution was cooled to -78 °C, a solution of 62 (106.1
mg, 0.21 mmol) in THF (1.5 mL) was added. The mixture was stirred
for 3 h at -78 °C and quenched with phosphate buffer solution (pH )
7). The aqueous layer was extracted with ether. The ethereal extract
was washed with water and brine, dried over sodium sulfate, and
concentrated under reduced pressure. The residue was purified by
column chromatography on silica gel (hexane/ethyl acetate ) 20/1) to
give 63 (98.4 mg, 83%). Diastereomers of 63 could be separated by
the column chromatography (silica gel, hexane/ethyl acetate ) 20/1).
1H NMR δ 0.00 (s, 3H), 0.06 (s, 3H), 0.86 (s, 9H), 0.91-0.98 (m,
7H), 1.33-1.38 (m, 28H), 1.42 (s, 3H), 1.59-1.64 (br, 3H), 2.07-
2.38 (br, 2H), 2.44 (t, 4H, J ) 7.5 Hz), 3.17 (d, 1H, J ) 8.3 Hz), 3.44
(d, 1H, J ) 11.5 Hz), 3.52 (dd, 1H, J ) 6.9, 10.6 Hz), 3.87-4.34 (m,
5H), 3.93 (t, 1H, J ) 8.1 Hz), 4.96 (d, 1H, J ) 11.9 Hz), 5.45 (dd, 1H,
J ) 8.1, 15.4 Hz), 5.72 (dt, 1H, J ) 6.8, 16.5 Hz), 7.24-7.31 (m,
5H); 13C NMR δ -4.5, -4.2, 13.7, 14.0, 14.2, 18.1, 21.8, 22.4, 23.8,
25.9, 28.9, 29.0, 29.1, 31.6, 42.7, 52.2, 60.6, 60.8, 72.7, 73.7, 76.4,
77.1, 82.1, 126.1, 126.6, 127.8, 130.8, 133.7, 139.1, 162.3, 164.5, 211.5;
IR (neat) 1687.0, 2856.0, 2929.0 cm-1; FABHRMS calcd for C41H64N2O6-
Si (M + Na) 731.4431, found 731.4420.
(3RS)-S-Ethyl 3-hydroxynonanethioate (14): To a solution of
ytterbium(III) trifluoromethanesulfonate (129.9 mg, 0.21 mmol) in
dichloromethane (30 mL) was added a solution of 16 (2.33 g, 20.4
mmol) in dichloromethane (20 mL) and 17 (4.85 g, 27.5 mmol) in
dichloromethane (20 mL) at 0 °C. After stirring for 1 h at 0 °C, the
reaction was quenched with saturated aqueous NaHCO3 solution, and
the aqueous layer was extracted with dichloromethane. The extract
was dried over sodium sulfate and concentrated under reduced pressure.
The residue was treated with THF: 1 N HCl ) 4:1 solution for 30
min. After hexane was added, the organic layer was separated, and
the aqueous layer was extracted with ether. The ethereal extract was
washed with water and brine, dried over sodium sulfate, and concen-
trated under reduced pressure. The residue was purified by column
chromatography on silica gel (hexane/ethyl acetate ) 20/1) to give 14
(4.05 g, 91%) as a colorless oil. 1H NMR δ 0.88 (t, 3H, J ) 6.6 Hz),
1.24-1.56 (m, 13H), 2.61-2.81 (m, 3H), 2.91 (q, 2H, J ) 7.5 Hz),
4.01-4.08 (m, 1H); 13C NMR δ 14.0, 14.6, 22.5, 23.3, 25.3, 29.1, 31.7,
36.5, 50.6, 68.6, 199.6; IR (neat) 1683.6, 2927.4, 3378.7, 3475.1 cm-1
.
(7RS)-1-Bromo-7-tridecanol (53): To a solution of 12 (2.24 g, 6.94
mmol) in methanol (21 mL) was added concentrated HCl (0.7 mL),
and the solution was stirred for 3 h at 50 °C. The mixture was cooled
to room temperature, diluted with water (60 mL), and neutralized with
potassium carbonate at 0 °C. The aqueous layer was extracted with
ether. The ethereal extract was washed with water and brine, dried
over sodium sulfate, and concentrated under reduced pressure. The
residue was purified by column chromatography on silica gel (hexane/
(1′S,4′R,16S,17S,18R)-17-Benzyloxy-18-(3′,6′-diethoxy-1′,4′-di-
methyl-4′H-2′,5′-diazyl)-16,18-dihydroxyoctadec-14-ene-7-one (64):
To a solution of 63 (68.4 mg, 0.096 mmol) in THF (3.0 mL) was added
a solution of tetrabutylammonium fluoride (1 N solution in THF, 0.4
mmol) at room temperature. After stirring for 4 h, the reaction was
quenched with phosphate buffer solution (pH ) 7). The aqueous layer
was extracted with ether, and the ethereal extract was washed with
10% aqueous citric acid solution, saturated aqueous NaHCO3 solution,
and brine. The organic layer was dried over sodium sulfate and
concentrated under reduced pressure. The residue was purified by
column chromatography on silica gel (hexane/ethyl acetate ) 10/1) to
give 64 (54.0 mg, 94%) as a white solid. 1H NMR δ 0.81 (t, 3H, J )
6.6 Hz), 0.99 (t, 3H, J ) 7.1 Hz), 1.20-1.49 (m, 22H), 1.94-2.07 (br,
2H), 2.30 (t, 4H, J ) 7.5 Hz), 2.72 (br, 1H), 3.13 (d, 1H, J ) 6.6 Hz),
3.47 (d, 1H, J ) 11.6 Hz), 3.63 (dd, 1H, J ) 7.1, 10.7 Hz), 3.69-4.15
(m, 5H), 4.20 (t, 1H, J ) 6.9 Hz), 4.48 (d, 1H, J ) 11.2 Hz), 5.38 (dd,
1H, J ) 7.4, 15.3 Hz), 5.74 (dt, 1H, J ) 6.8, 15.2 Hz), 7.17-7.30 (m,
1
ethyl acetate ) 10/1) to give 53 (1.72 g, quant.) as a colorless oil. H
NMR δ 0.89 (t, 3H, J ) 6.9 Hz), 1.29-1.60 (m, 21H), 1.68-2.00 (m,
2H), 3.41 (t, 2H, J ) 6.9 Hz), 3.59 (br, 1H); 13C NMR d 14.1, 22.6,
25.4, 25.6, 28.1, 28.8, 29.3, 31.8, 32.7, 34.0, 37.3, 37.5, 71.9; HRMS
calcd for C13H27BrO (M+) 278.1245, found 278.1229.
(7RS)-1-Bromo-7-trimethylsiloxytridecane (54): To a solution of
53 (1.94 g, 6.16 mmol) in dichloromethane (21 mL) was added a
solution of triethylamine (1.34 g, 12.4 mmol) in dichloromethane (7.0
mL) and trimethylsilyl chloride (1.25 g, 12.3 mmol) in dichloromethane
(7.0 mL) at 0 °C. The mixture was warmed to room temperature and
stirred for 15 min. The reaction was then quenched with water, and
the aqueous layer was extracted with dichloromethane. The extract

Syntheses of Antifungal Sphingofungins
J. Am. Chem. Soc., Vol. 120, No. 5, 1998 919
5H); 13C NMR δ 13.9, 14.0, 14.2, 21.7, 22.4, 23.8, 27.2, 28.8, 28.9,
29.0, 29.1, 31.6, 32.4, 42.7, 42.8, 52.4, 60.4, 60.9, 61.0, 74.0, 74.6,
75.0, 82.0, 127.1, 127.5, 128.3, 129.0, 134.6, 138.1, 163.2, 164.5, 211.6;
IR (neat) 1689.0, 2855.0, 2929.0, 3361.0 cm-1; FABHRMS calcd for
C35H56N2O6 (M + Na) 623.4036, found 623.4033.
aqueous layer was extracted with tert-butyl alcohol. The extract was
washed with water and was concentrated under reduced pressure. The
residue was purified by column chromatography on silica gel (chloroform/
26
methanol ) 10/1) to give 8 (4.3 mg, 72%) as a white solid. [R]D
1
+0.8 (c ) 0.33, MeOH); H NMR (CD3OD) δ 0.89 (t, 3H, J ) 6.6
(2S,3S,4R,5S)-2-Amino-4-benzyloxy-2-methyl-3,5-dihydroxy-14-
oxoeicos-6-enoic acid (65): To a solution of 64 (54.0 mg, 0.09 mmol)
in THF (4.0 mL) was added p-toluensulfonic acid (171.2 mg, 0.9 mmol)
at room temperature. After stirring for 1 h, the mixture was neutralized
with a resin (IRA-93ZU). The resin was filtered off, and the filtrate
was concentrated under reduced pressure to give a mixture of an ester
and a lactone. To a solution ester and lactone in methanol (4.0 mL)
was added 1 N NaOH aqueous (4.0 mL) at room temperature. After
stirring for 30 min, the solution was neutralized with a resin (IRC-76).
The resin was filtered off, and the filtrate was extracted with ether.
The ethereal extract was washed with water and brine, dried over
sodium sulfate, and concentrated under reduced pressure. The residue
was purified by column chromatography on silica gel (chloroform/
methanol ) 10/1) to give 65 (25.6 mg, 58%, two steps) as a white
solid. [R]D26 +8.2 (c ) 0.23, C6H6); 1H NMR (CD3OD) δ 0.88 (t, 3H,
J ) 3.5 Hz), 1.12-1.56 (m, 19H), 2.03-2.15 (br, 2H), 2.43 (t, 4H, J
) 7.2 Hz), 3.77 (dd, 1H, J ) 1.8, 7.1 Hz), 3.95 (d, 1H, J ) 1.7 Hz),
4.43 (t, 1H, J ) 6.9 Hz), 4.55 (d, 1H, J ) 10.2 Hz), 5.08 (d, 1H, J )
9.9 Hz), 5.58 (dd, 1H, J ) 7.3, 15.5 Hz), 5.76 (dt, 1H, J ) 6.4, 14.1
Hz), 7.23-7.52 (m, 5H); 13C NMR (CD3OD) δ 14.4, 22.0, 23.6, 24.9,
30.0, 30.2, 32.8, 33.4, 43.5, 66.2, 73.0, 76.0, 76.5, 85.5, 129.1, 129.6,
130.0, 130.8, 134.7, 139.5, 214.4; FABHRMS calcd for C28H45NO6
(M + Na) 514.3144, found 514.3159.
Hz), 1.28-1.55 (m, 19H), 2.05 (br, 2H), 2.44 (t, 4H, J ) 7.4 Hz), 3.69
(d, 1H, J ) 7.3 Hz), 3.86 (br, 1H), 4.10 (t, 1H, J ) 7.3 Hz), 5.47 (dd,
1H, J ) 7.8, 15.6 Hz), 5.78 (dt, 1H, J ) 6.7, 15.6 Hz); 13C NMR
(CD3OD) δ 14.4, 21.8, 23.6, 24.9, 30.0, 30.2, 32.8, 33.5, 43.5, 67.7,
72.4, 75.7, 76.2, 130.2, 135.7, 214.4; FABHRMS calcd for C21H39-
NO6 (M + H) 402.2856, found 402.2861.
Acknowledgment. We are grateful to Drs. N. Yasuda, K.
E. Wilson, O. Hensens, and I. Shinkai (Merck Research
Laboratories) for providing us with an authentic sample of
sphingofungin B and spectral data. We also thank Ms. Masae
Matsumura, Mr. Shunsuke Iwamoto (SUT), Ms. Mamiko Haraki
(NIID), and Ms. Tomoko Hara (JST) for their experimental
supports. This work was partially supported by CREST, Japan
Science and Technology Corporation (JST), a Grant-in-Aid for
Scientific Research from the Ministry of Education, Science,
Sports, and Culture, Japan, and a SUT Special Grant for
Research Promotion.
Supporting Information Available: Experimental proce-
dures for the synthesis of compounds 22, 23, 24, 25, 26, 27a-
d, 28, 29, 30, 31c, 42c (from 46c), 46b-d, 48, 49, 50, 51, 52,
55, 56, 57, 58, 60, 61, and 62 including spectral data (17 pages).
See any current masthead page for ordering and Internet access
instructions.
(2S,3R,4R,5S)-2-Amino-2-methyl-3,4,5-trihydroxy-14-oxoeicos-
6-enoic acid (sphingofungin F) (8): To a solution of 65 (7.3 mg, 0.015
mmol) in dichloromethane (1.0 mL) was added trichloroborane 1 N
solution in hexane (0.045 mmol) dropwise at -78 °C. After stirring
for 10 min, the reaction was quenched with methanol (1.0 mL). The
solution was warmed to room temperature and diluted with water. The
JA9730829