Total synthesis of an immunosuppressive glycolipid, (2S,3S,4R)-1-O- (α-D-galactosyl)-2-tetracosanoylamino-1,3,4-nonanetriol

Article abstract of DOI:10.1021/jo048151y

(Chemical Equation Presented) A practical and efficient total synthesis of (2S,3S,4R)-1-O-(α-D-galactosyl)-2-tetracosanoylamino-1,3,4-nonanetriol, OCH 1b, a potential therapeutic candidate for Th1-mediated autoimmune diseases, is described. The synthesis

Full text of DOI:10.1021/jo048151y

Total Synthesis of an Immunosuppressive
Glycolipid, (2S,3S,4R)-1-O-
(r-D-Galactosyl)-2-
tetracosanoylamino-1,3,4-nonanetriol
FIGURE 1. Structure of KRN7000 1a and OCH 1b.
Kenji Murata,† Tetsuya Toba,† Kyoko Nakanishi,†
Bitoku Takahashi,† Takashi Yamamura,‡
Sachiko Miyake,‡ and Hirokazu Annoura*,†
(IL)-4 production, 1b induces a predominant production
of IL-4, a key Th2 cytokine controlling autoimmunity.
Compound 1b is significantly effective in animal models
of Th1-mediated autoimmune diseases such as experi-
mental autoimmune encephalomyelitis (EAE) and col-
lagen-induced arthritis (CIA), while 1a showed only a
minor effect.3,4 It has recently been demonstrated that
conversion of 1a to its C-glycoside analogue leads to
striking enhancement of activity on in vivo animal models
of malaria and lung cancer.5 Furthermore, similar sub-
stances including a tetraglycosylated glycolipid have
recently been isolated from Agelas Clathrodes.6 Conse-
quently, considerable attention has been generated among
synthetic chemists toward 1a, 1b, and their derivatives
as new synthetic targets because of their distinctive
biological and pharmacological properties as well as
unique structural features. We present herein a practical
and efficient total synthesis of immunosuppressive gly-
colipid 1b.7
Daiichi Suntory Biomedical Research Co., Ltd., 1-1-1,
Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka
618-8513, Japan, and Department of Immunology, National
Institute of Neuroscience, National Center for Neuroscience
and Psychiatry, Tokyo 187-8502, Japan
hirokazu_annoura@dsup.co.jp
Received October 20, 2004
The significant structural difference between 1a and
1b is the length of a sphingosine side chain R2. Reported
procedures2,8 for the syntheses of 1a and its sphingosine
derivatives, which essentially utilize Wittig-type or aldol-
type reaction for the installation of the sphingosine side
chain, gave low overall yields for 1b and its analogues
with a chain length shorter than C5 for R2 and proved to
be impractical.9 Our strategy for resolving this problem
is based upon the direct alkylation on epoxide 5, which
A practical and efficient total synthesis of (2S,3S,4R)-1-O-
(R-D-galactosyl)-2-tetracosanoylamino-1,3,4-nonanetriol, OCH
1b, a potential therapeutic candidate for Th1-mediated
autoimmune diseases, is described. The synthesis incorpo-
rates direct alkylation onto epoxide 5 and stereospecific
halide ion catalyzed R-glycosidation reaction. A key inter-
mediate 10 was obtained in only eight steps and 37% overall
yield from commercially available D-arabitol 2, and the total
synthesis of 1b was accomplished in 12 steps and 19%
overall yield. This method will enable the synthesis of a
variety of phytosphingolipids, especially that with the
shorter sphingosine side chain than 1a, in a highly stereo-
selective manner.
(2) (a) Morita, M.; Motoki, K.; Akimoto, K.; Natori, T.; Sakai, T.;
Sawa, E.; Yamaji, K.; Koezuka, Y.; Kobayashi, E.; Fukushima, H. J.
Med. Chem. 1995, 38, 2176. (b) Morita, M.; Sawa, E.; Yamaji, K.; Sakai,
T.; Natori, T.; Koezuka, Y.; Fukushima, H.; Akimoto, K. Biosci.
Biotechnol. Biochem. 1996, 60, 288. (c) Takikawa, H.; Muto, S.; Mori,
K. Tetrahedron 1998, 54, 3141. (d) Graziani, A.; Passacantilli, P.;
Piancatelli, G.; Tani, S. Tetrahedron: Asymmetry 2000, 11, 3921. (e)
Plettenburg, O.; Bodmer-Narkevitch, V.; Wong C.-H. J. Org. Chem.
2002, 67, 4559.
Natural killer (NK) T cells are potent producers of
immunoregulatory cytokines and specific for glycolipid
antigens bound by a nonpolymorphic major histocom-
patibility complex (MHC) class I-like molecule, CD1d.1
The glycolipids, an R-galactosylceramide named KRN7000
1a2 and an altered analogue, OCH 1b,3 possessing a
shorter C5 sphingosine side chain, have been identified
as NKT cell ligands (Figure 1). Whereas 1a has been
shown to cause both interferon (IFN)-γ and interleukin
(3) (a) Miyamoto, K.; Miyake, S.; Yamamura, T. Nature 2001, 413,
531. (b) Yamamura, T.; Miyake, S. PCT Int. Appl. WO 2003/016326,
2003; Chem. Abstr. 2003, 138, 205292m. (c) Yamamura, T.; Miyamoto,
K.; Illes, Z.; Pal, E.; Araki, M.; Miyake, S. Curr. Top. Med. Chem. 2004,
4, 561. (d) Oki, S.; Chiba, A.; Yamamura, T.; Miyake, S. J. Clin. Invest.
2004, 113, 1631.
(4) Chiba, A.; Oki, S.; Miyamoto, K.; Hashimoto, H.; Yamamura,
T.; Miyake, S. Arthritis Rheum. 2004, 50, 305.
(5) (a) Schmieg, J.; Yang, G.; Frank, R. W.; Tsuji, M. J. Exp. Med.
2003, 198, 1631. (b) Yang, G.; Schmieg, J.; Tsuji, M.; Frank, R. W.
Angew. Chem., Int. Ed. 2004, 43, 3818.
(6) Costantino, V.; Fattorusso, E.; Imperatore, C.; Mangoni, A. J.
Org. Chem. 2004, 69, 1174.
* To whom correspondence should be addressed. Phone: +81-75-
962-8188. Fax: +81-75-962-6448.
(7) Annoura, H.; Murata, K.; Yamamura, T. PCT Int. Appl. WO2004/
072091, 2004; Chem. Abstr. 2004, 141, 225769n.
† Daiichi Suntory Biomedical Research Co., Ltd.
(8) (a) Schmidt, R. R., Maier, T. Carbohydr. Res. 1988, 174, 169. (b)
Kobayashi, S.; Hayashi, T.; Kawasuji, T. Tetrahedron Lett. 1994, 35,
9573. (c) Azuma, H.; Tamagaki, S.; Ogino, K. J. Org. Chem. 2000, 65,
3538. (d) Fernandes, R. A.; Kumar, P. Tetrahedron Lett. 2000, 41,
10309. (e) Ndakala, J.; Hashemzadeh, M.; So, R. C.; Howell, A. R. Org.
Lett. 2002, 4, 1719. (f) Ayad, T.; Ge´nisson, Y.; Verdu, A.; Baltas, M.;
Gorrichon, L. Tetrahedron Lett. 2003, 44, 579. (g) Lin, C.-C.; Fan, G.-
T.; Fang, J.-M. Tetrahedron Lett. 2003, 44, 5281. (h) Chiu, H.-Yi; Tzou,
D.-L. J. Org. Chem. 2003, 68, 5788.
‡ National Institute of Neuroscience, NCNP.
(1) For reviews: (a) Porcelli, S. A.; Modlin, R. L. Annu. Rev.
Immunol. 1999, 17, 297. (b) Hong, S.; Scherer, D. C.; Singh, N.;
Mendiratta, S. K.; Serizawa, I.; Koezuka, Y.; Van Kaer, L. Immunol.
Rev. 1999, 169, 31. (c) Sidobre, S.; Kronenberg, M. J. Immunol.
Methods 2002, 268, 107. (d) Wilson, M. T.; Van Kaer, L. Curr. Pharm.
Des. 2003, 9, 201. (e) Brigl, M.; Brenner, M. B. Annu. Rev. Immunol.
2004, 22, 817.
10.1021/jo048151y CCC: $30.25 © 2005 American Chemical Society
Published on Web 02/16/2005
2398
J. Org. Chem. 2005, 70, 2398-2401

SCHEME 1a
SCHEME 2a
a Reagents and conditions: (a) 11a, BF3‚Et2O, MS4Å, CHCl3,
-50 °C, 57% for 12a, 25% for 12b; (b) 11b, n-Bu4NBr, MS4Å,
DMF-toluene (1:2.5), rt, 68% for 12a; (c) H2, Lindlar catalyst,
EtOH, rt, quant; (d) n-C23H47COOH, EDCI, HOBt, i-Pr2NEt,
DMF-CH2Cl2 (1:3.5), 40 °C, 89%; (e) (i) HCl-dioxane, rt; (ii) H2,
cat. Pd(OH)2, MeOH-CHCl3 (3:1), rt, 84%
a Reagents and conditions: (a) PhCHO, dry HCl, rt, 91%; (b)
p-TsCl, Et3N, cat. Bu2SnO, CH2Cl2, rt, quant; (c) t-BuOK, THF,
rt, 91%; (d) n-Bu2CuLi, THF, -40 °C, 98%; (e) MsCl, pyridine, -40
°C, 93%; (f) H2, cat. Pd(OH)2, EtOH, rt, quant; (g) NaN3, DMF, 95
°C, 66%; (h) (i) cat. p-TsOH, 2,2-dimethoxypropane, rt; (ii) MeOH,
rt, 75%.
Deprotection of the benzylidene acetal in 7 by hydrogen-
ation at atmospheric pressure in the presence of pal-
ladium hydroxide [Pd(OH)2] in EtOH and subsequent
azidation of 8 with sodium azide in DMF afforded 9 in
66% overall yield. Protection of the vicinal diols in 9 with
a catalytic amount of p-toluenesulfonic acid (p-TsOH) in
2,2-dimethoxypropane at room temperature and quench-
ing with MeOH afforded 3,4-isopropylidene acetal 10 in
75% yield.
As the key intermediate 10, a glycosyl acceptor, was
available, we next examined R-selective glycosidation
reaction employing a variety of Lewis acids. After exten-
sive experimentation, we found that glycosidation cata-
lyzed by BF3‚Et2O or n-Bu4NBr with molecular sieves 4Å
(MS4Å) worked well, but AgClO4 reported for the syn-
thesis2 of 1a gave only the undesired â-glycosylated
product. Thus, treatment of 10 with benzyl protected
galactosyl fluoride 11a (1.8 equiv) in the presence of BF3‚
Et2O and MS4Å in CHCl3 at -50 °C afforded R-galacto-
sylceramide 12a in 57% yield along with its â-isomer 12b
in 25% yield (Scheme 2). The stereochemistry of galac-
toside linkage was unambiguously determined by their
NMR spectra13 as well as conversion of 12a into 1b (vide
infra). Surprisingly, when benzyl protected galactosyl
bromide 11b14a (1.8 equiv) and n-Bu4NBr14b (3 equiv) with
MS4Å were employed in toluene-DMF (2.5:1) at room
temperature, 12a was exclusively obtained in 68% yield.
The corresponding â-galactosylated isomer 12b could not
be detected on TLC and NMR spectra. Upon using other
ammonium bromides such as n-Hex4NBr and Et4NBr, the
isolated yield of 12a was decreased.
has adequate stereocenters for the desired sphingosine
side chain.10
Upon treatment of compound 3,11 which was readily
prepared from D-arabitol 2 and benzaldehyde in 91%
yield, with p-toluenesulfonyl chloride (p-TsCl) and tri-
ethylamine in the presence of a catalytic amount of
dibutyltin oxide (Bu2SnO),12 regiospecific tosylation pro-
ceeded at the primary alcohol moiety to give 4 quanti-
tatively (Scheme 1). The use of Bu2SnO not only reduced
the cost of this transformation but also greatly simplified
the purification process since the yield was decreased to
less than 30% when the reaction was carried out in the
absence of Bu2SnO. Treatment of 4 with t-BuOK pro-
duced the requisite epoxide 5 in 91% yield. Direct
n-butylation onto 5 using organocopper lithium reagent
in THF at -40 to -20 °C afforded 1,3-O-benzylidene-
1,2,3,4-nonanetetrol 6 in 98% yield as the single product.
Regioselective mesylation of the axial-OH in 6 with 1
equiv of methanesulfonyl chloride (MsCl) in pyridine at
-40 °C to room temperature afforded 7 in 93% yield.
(9) According to the procedure reported in ref 2a, periodate oxidation
of readily available tri-O-benzyl-D-galactose followed by Wittig-type
reaction with a 5-fold molar excess of butylidene(triphenyl)phosphorane
gave the desired (2R,3S,4R)-1,3,4-tri-O-benzyl-5-nonane-1,2,3,4-tetraol
in less than 20% yield and consequently gave 1b in low overall yield;
see ref 3b. Also, when the more practical method for 1a reported by
Wong et al.2e was pursued for 1b, similar Wittig reaction employing
3,4-di-O-benzyl-2-deoxy-6-O-triisopropylsilyl-D-galactopyranoside and
propylidene(triphenyl)phosphorane resulted in complex mixtures con-
taining an unavoidable byproduct in which the 3-benzyloxy group of
galactopyranoside was eliminated. Therefore, our method is more
efficient and practical for the synthesis of 1b than those previously
reported; however, this might not be the case for the synthesis of 1a.
(10) During the preparation of this manuscript, Savage et al. have
reported an alternative and efficient route for 1b, although it requires
the separation step of a 2:1 mixture of diastereomeric diols: Goff, R.
D.; Gao, Y.; Mattner, J.; Zhou, D.; Yin, N.; Cantu, C., III; Teyton, L.;
Bendelac, A.; Savage, P. B. J. Am. Chem. Soc. 2004, 126, 13602.
(11) (a) Hudson, C. S.; Hann, R. M.; Haskins, W. T. J. Am. Chem.
Soc. 1943, 65, 1663. (b) Hough, L.; Theobald, R. S. Methods Carbohydr.
Chem. 1963, 1, 94. (c) Dew, K. N.; Church, T. J.; Basu, B.; Vuorinen,
T.; Serianni, A. S. Carbohydr. Res. 1996, 284, 135.
(13) In the 13C NMR (100 MHz, CDCl3), the signal attributable to
the anomeric carbon of 12a appeared at δ 99.3, whereas that of 12b
was at δ 104.1. For 13C NMR of glycosides: Pretsch, E.; Buhlmann,
P.; Affolter, C. In Structure Determination of Organic Compounds, 3rd
ed.; Springer-Verlag: 2000; pp 152-153. Also, in the 1H NMR (400
MHz, CDCl3/CD3OD 3:1) of 1b derived from 12a, the signal assignable
to the hydrogen on the anomeric position was at δ 4.71 (d, 1H, J ) 3.8
Hz), showing R-glycosidation product.
(14) Halide ion catalyzed glycosidation reaction was reported for the
synthesis of R-linked disaccharide: (a) Spohr, U.; Le, N.; Ling, C.-C.;
Lemieux, R. U. Can. J. Chem. 2001, 79, 238. (b) Lemieux, R. U.;
Hendriks, K. B.; Stick, R. V.; James, K. J. Am. Chem. Soc. 1975, 97,
4056. Similar glycosidation methodology although in lower yield was
reported: (c) Vo-Hoang, Y.; Micouin, L.; Ronet, C.; Gachelin, G.; Bonin,
M. ChemBioChem 2003, 4, 27.
(12) Martinelli, M. J.; Nayyar, N. K.; Moher, E. D.; Dhokte, U. P.;
Pawlak, J. M.; Vaidyanathan, R. Org. Lett. 1999, 1, 447.
J. Org. Chem, Vol. 70, No. 6, 2005 2399

Na2SO4, and concentrated in vacuo. The residue was purified
by column chromatography (n-hexane/EtOAc 1:1) to give 5 (26.2
g, 91%) as a white solid: 1H NMR (CDCl3) δ 7.52-7.34 (m, 5H),
5.57 (s, 1H), 4.25 (dd, 1H, J ) 12, 1.8 Hz), 4.08 (dd, 1H, J ) 12,
1.2 Hz), 3.78-3.75 (m, 2H), 3.35-3.31 (m, 1H), 2.93-2.84 (m,
3H); 13C NMR (CDCl3) δ 137.4, 129.3, 128.4, 126.0, 101.4, 79.7,
72.3, 64.4, 50.8, 45.9; MS-ESI (m/z) 223 [M + H]+; HRMS-FAB
(m/z) [M + H]+ calcd for C12H15O4, 223.0971, found 223.0895.
(2R,3S,4R)-1,3-O-Benzylidene-1,2,3,4-nonanetetrol (6).
To a suspension of cupper iodide (I) (42.9 g, 225 mmol) in dry
THF (560 mL) was added dropwise a solution of n-butyllithium
(341 mL, 900 mmol, 2.64 M in hexane) at -40 °C under a
nitrogen atmosphere. The reaction mixture was stirred for 30
min at -30 °C and then a solution of epoxide 5 (50.0 g, 225
mmol) in dry THF (400 mL) was added dropwise at -40 °C. After
being stirred for 3 h at -20 °C, sat. NaHCO3 aq. was added and
the product was extracted with EtOAc. The organic layer was
washed with brine, dried over anhydrous MgSO4, and concen-
trated in vacuo to give 6 (61.7 g, 98%) as a white solid: 1H NMR
(CDCl3) δ 7.52-7.50 (m, 2H), 7.42-7.38 (m, 3H), 5.60 (s, 1H),
4.28 (dd, 1H, J ) 12, 1.8 Hz), 4.05 (1H, dd, J ) 12, 1.3 Hz),
3.95-3.88 (m, 2H), 3.71 (dd, 1H, J ) 6.6, 1.3 Hz), 3.25 (d, 1H, J
) 8.7 Hz), 2.34 (d, 1H, J ) 4.5 Hz), 1.73-1.53 (m, 2H), 1.40-
1.30 (m, 6H), 0.90 (t, 3H, J ) 6.7 Hz); 13C NMR (CDCl3) δ 129.1,
128.3, 126.0, 105.0, 101.2, 81.3, 72.6, 71.2, 63.8, 32.8, 31.8, 25.2,
22.6, 14.0; MS-FAB (m/z) 281 [M + H]+; HRMS-FAB (m/z) [M
+ H]+ calcd for C16H25O4, 281.1753, found 281.1658.
(2R,3S,4R)-1,3-O-Benzylidene-2-O-methanesulfonyl-
1,2,3,4-nonanetetrol (7). To a solution of 6 (3.90 g, 13.9 mmol)
in dry pyridine (142 mL) was added methansulfonyl chloride
(1.05 mL) at -40 °C under a nitrogen atmosphere. The mixture
was stirred at the same temperature for 5 h and then gradually
warmed to room temperature over 16 h. Azeotropic removal of
pyridine by using toluene twice gave a residue that was
subjected to column chromatography (n-hexane/EtOAc 3:2) to
give 7 (4.65 g, 93%) as a white solid: 1H NMR (CDCl3) δ 7.51-
7.48 (m, 2H), 7.42-7.35 (m, 3H), 5.59 (s, 1H), 4.99 (d, 1H, J )
1.4 Hz), 4.53 (dd, 1H, J ) 13, 1.6 Hz), 4.18 (dd, 1H, J ) 13, 1.1
Hz), 3.84-3.75 (m, 2H), 3.19 (s, 3H), 1.60-1.27 (m, 8H), 0.90 (t,
3H, J ) 6.8 Hz); 13C NMR (CDCl3) δ 129.3, 128.4, 126.1, 101.1,
80.9, 70.4, 70.0, 68.7, 38.7, 33.0, 32.0, 25.1, 22.8, 14.2; MS-FAB
(m/z) 359 [M + H]+; HRMS-FAB (m/z) [M + H]+ calcd for
Selective reduction of the azido group of 12a was
achieved by hydrogenation with Lindlar catalyst in EtOH
at room temperature to give amine 13 quantitatively.
Compound 13 was acylated with n-tetracosanoic acid in
the presence of 1-[3-(dimethylamino)propyl]-3-ethylcar-
bodiimide hydrochloride (EDCI), 1-hydroxybenzotriazole
(HOBt) and N,N-diisopropylethylamine (i-Pr2NEt) at 40
°C in DMF-CH2Cl2 (1:3.5) to afford amide 14 in 89%
yield. Finally, deprotection of the isopropylidene acetal
of 14 under acidic conditions and subsequent removal of
the benzyl groups by hydrogenation with Pd(OH)2 in
MeOH-CHCl3 (3:1) at room temperature furnished 1b
in 84% yield. The synthetic sample displayed satisfactory
1H and 13C NMR spectra, FABMS, and elemental analy-
sis [mp 142-145 °C (recrystalized from EtOH/H2O), [R]30
D
+53.9 (c 0.5, pyridine)].
In conclusion, we have developed an efficient and
practical protocol for the synthesis of 1b involving 12
steps starting from commercially available D-arabitol 2
in 19% overall yield. The key intermediate 10 as a
glycosyl acceptor was obtained in only eight steps and
37% overall yield. Our method, amenable for large-scale
synthesis, can provide a dozen grams of 1b and enables
the synthesis of a variety of phytosphingolipids related
to 1a and 1b, especially those with the shorter sphin-
gosine side chain or substituents other than aliphatic
alkyl groups, in a highly stereoselective manner. The
synthesis and structure-activity relationships of this
series of compounds will be reported elsewhere in due
course.7
Experimental Section
1,3-O-Benzylidene-D-arabitol (3). According to the reported
procedures,11 dry HCl was slowly bubbled into a mixture of
D-arabitol 2 (98.8 g, 649 mmol) and benzaldehyde (78.8 mL, 775
mmol) for 15 min at room temperature. The mixture was allowed
to stand at room temperature for 18 h. The resulting solid
crystalline mass was broken up and placed in an evacuated
desiccator containing KOH and H2SO4 for 24 h. The mass was
triturated with Et2O, neutralized with sat. NaHCO3 aq., and
filtered and washed with H2O until the pH of the filtrate was
neutral. The product was washed with Et2O and recrystallized
from 2-PrOH containing 0.5% v/v NH4OH to give 3 (142.2 g, 91%
C
17H27O6S, 359.1528, found 359.1448.
(2R,3S,4R)-2-O-Methanesulfonyl-1,2,3,4-nonanetetrol (8).
To a solution of 7 (87.0 mg, 242 µmol) in EtOH (5.0 mL) was
added palladium hydroxide (Pd(OH)2) (45 mg). After hydrogena-
tion of the mixture for 16 h at atmospheric pressure, the catalyst
was filtered off and the filtrate was concentrated in vacuo to
give 8 (65.7 mg, quant) as a white solid: 1H NMR (CDCl3) δ
5.03-5.00 (m, 1H), 4.02-4.00 (m, 2H), 3.62-3.60 (m, 2H), 3.19
(s, 3H), 1.76-1.72 (m, 1H), 1.56-1.28 (m, 7H), 0.90 (t, 3H, J )
6.7 Hz); 13C NMR (CD3OD) δ 83.8, 74.1, 71.3, 62.6, 38.6, 34.6,
33.2, 26.1, 23.8, 14.4; MS-ESI (m/z) 293 [M + Na]+; HRMS-
FAB (m/z) [M - OH]+ calcd for C10H21O5S, 253.1110, found
253.1069.
(2S,3S,4R)-2-Azido-1,3,4-nonanetriol (9). To a solution of
8 (36.9 mg, 136 µmol) in dry DMF (1.0 mL) was added NaN3
(17.7 mg, 272 µmol) under a nitrogen atmosphere. The mixture
was stirred for 3 h at 95 °C and then quenched with water. After
being extracted with ethyl acetate, the organic layer was washed
with brine twice, dried over anhydrous Na2SO4, and concen-
trated in vacuo. The residue was purified by column chroma-
tography (CH2Cl2/MeOH 15:1) to give 9 (19.5 mg, 66%) as a white
solid: 1H NMR (CDCl3) δ 4.05-3.98 (m, 1H), 3.91-3.74 (m, 3H),
3.71-3.66 (m, 1H), 2.67 (brs 1H), 2.52 (d, 1H, J ) 4.4 Hz), 2.20
(brs, 1H), 1.61-1.52 (m, 2H), 1.40-1.31 (m, 6H), 0.91 (t, 3H, J
) 6.6 Hz); 13C NMR (CDCl3) δ 74.8, 72.7, 63.3, 61.9, 32.0, 31.9,
25.6, 22.7, 14.2; MS-FAB (m/z) 218 [M + H]+; HRMS-FAB (m/
z) [M + H]+ calcd for C9H20N3O3, 218.1505, found 218.1469.
(2S,3S,4R)-2-Azido-3,4-O-isopropylidene-1,3,4-nonane-
triol (10). To a solution of 9 (4.00 g, 18.4 mmol) in dimethox-
ypropane (73 mL) was added a catalytic amount of p-toluene-
sulfonic acid monohydrate (175 mg, 92 µmol) at 0 °C. Stirring
was continued for 2 h at room temperature. The mixture was
1
yield) as colorless crystals; mp 130-131 °C; H NMR (CD3OD)
δ 7.51-7.30 (m, 5H), 5.58 (s, 1H), 4.18 (d, 1H, J ) 12 Hz), 4.11
(d, 1H, J ) 12 Hz), 3.87-3.28 (m, 5H); HRMS calcd for C12H17O5
[M + H]+ 241.1076, found 241.1086.
1,3-O-Benzylidene-5-O-toluenesulfonyl-D-arabitol (4). To
a suspension of 3 (34.0 g, 141 mmol) in CH2Cl2 (1200 mL) were
added p-toluenesulfonyl chloride (27.0 g, 141 mmol), triethyl-
amine (19.7 mL, 141 mmol) and dibutyltinoxide (702 mg, 2.82
mmol) at 0 °C. After being stirred for 21 h at room temperature,
the mixture was concentrated in vacuo. The obtained residue
was purified by column chromatography (CH2Cl2/MeOH 20:1)
to give 4 (55.3 g, quant) as a white solid: 1H NMR (DMSO-d6)
δ 7.73 (d, 2H, J ) 8.2 Hz), 7.37-7.24 (m, 7H), 5.43 (s, 1H), 5.34
(d, 1H, J ) 6.1 Hz), 4.77 (d, 1H, J ) 6.5 Hz), 4.11 (dd, 1H, J )
9.8, 1.9 Hz), 4.04-3.85 (m, 4H), 3.71 (d, 1H, J ) 9.2 Hz), 3.59
(d, 1H, J ) 5.7 Hz), 2.32 (s, 3H); 13C NMR (CDCl3) δ 145.1, 137.3,
132.5, 129.9, 129.1, 128.2, 128.0, 125.8, 101.0, 77.9, 72.4, 70.9,
67.6, 62.7, 21.6; MS-ESI (m/z) 395 [M + H]+; HRMS-FAB (m/
z) [M + H]+ calcd for C19H23O7S, 395.1164, found 395.1189.
4,5-Anhydro-1,3-O-benzylidene-D-arabitol (5). To a solu-
tion of 4 (51.1 g, 130 mmol) in dry THF (800 mL) was added
potassium tert-butoxide (18.1 g, 161 mmol) at 0 °C. The reaction
mixture was stirred for 38 h at room temperature and then
quenched with water. After being extracted with ethyl acetate,
the organic layer was washed with brine, dried over anhydrous
2400 J. Org. Chem., Vol. 70, No. 6, 2005

quenched with MeOH and then stirred for 1 h at room temper-
ature. Removal of the solvent gave a residue, which was purified
by column chromatography (n-hexane/EtOAc 4:1) to give 10 (3.61
g, 75%) as a colorless oil: 1H NMR (CDCl3) δ 4.21-4.16 (m, 1H),
4.02-3.95 (m, 2H), 3.90-3.84 (m, 1H), 3.50-3.45 (m, 1H), 2.11
(t, 1H, J ) 5.6 Hz), 1.63-1.54 (m, 2H), 1.43 (s, 3H), 1.40-1.34
(m, 9H), 0.91(t, 3H, J ) 6.9 Hz); 13C NMR (CDCl3) δ 108.6, 77.8,
76.6, 63.9, 61.2, 31.8, 29.4, 28.0, 26.2, 25.6, 22.6, 14.0; MS-ESI
(m/z) 280 [M + Na]+; HRMS-FAB (m/z) [M + H]+ calcd for
(761 mg, 3.97 mmol) and 1-hydroxybenzotriazol (HOBt) (536 mg,
3.97 mmol) at 0 °C. After the mixture was stirred for 30 min at
room temperature, 13 (2.46 g, 3.26 mmol) and i-Pr2NEt (1.38
mL, 7.97 mmol) in CH2Cl2 (120 mL) were added and stirred for
16 h at 30 °C. The mixture was diluted with EtOAc/Et2O (4:1)
and sat. NaHCO3 aq., and then the organic layer was separated
and washed with 1 M HCl aq. and brine, and dried over
anhydrous MgSO4. Removal of the solvent gave a residue, which
was purified by column chromatography (n-hexane/EtOAc 3:1)
to give 14 (3.25 g, 89%) as a white solid: 1H NMR (CDCl3) δ
7.41-7.24 (m, 20H), 6.28 (d, 1H, J ) 8.4 Hz), 4.95-4.90 (m, 2H),
4.83-4.73 (m, 2H), 4.75 (d, 1H, J ) 12 Hz), 4.66 (d, 1H, J ) 11
Hz), 4.58 (d, 1H, J ) 12 Hz), 4.49 (d, 1H, J ) 12 Hz), 4.38 (d,
1H, J ) 12 Hz), 4.13-4.03 (m, 4H), 3.98 (t, 1H, J ) 6.2 Hz),
3.93-3.90 (m, 3H), 3.63-3.53 (m, 2H), 3.39 (dd, 1H, J ) 9.4,
5.7 Hz), 2.08-1.95 (m, 2H), 1.55-1.25 (m, 50H), 1.40 (s, 3H),
1.32 (s, 3H), 0.90-0.84 (m, 6H); 13C NMR (CDCl3) δ 172.4, 138.7,
138.4, 137.6, 128.5, 128.4, 128.4, 128.4, 128.3, 128.0, 127.9, 127.8,
127.7, 127.6, 127.5, 107.8, 99.9, 79.0, 77.8, 76.8, 75.5, 74.8, 74.7,
73.6, 73.5, 73.0, 70.8, 69.9, 69.6, 48.7, 36.8, 31.9, 31.8, 29.7, 29.7,
29.6, 29.5, 29.4, 29.3, 28.9, 28.2, 26.2, 26.0, 25.7, 22.7, 22.6, 14.1,
14.1; MS-FAB 1105 [M + H]+; HRMS-FAB (m/z) [M + H]+
calcd for C70H106NO9, 1104.7868, found 1104.7589.
C
12H24N3O3, 258.1818, found 258.1737.
(2S,3S,4R)-2-Azido-3,4-O-isopropylidene-1-O-(2,3,4,6-tetra-
O-benzyl-R-D-galactosyl)-1,3,4-nonanetriol (12a). To a sus-
pension of 10 (100 mg, 389 µmol), 11b (428 mg, 710 µmol), and
molecular sieves 4Å (powder, 340 mg) in dry toluene (3.4 mL)
and dry DMF (1.4 mL) was added tetra-n-butylammonium
bromide (n-Bu4NBr) (377 mg, 1.17 mmol) under a nitrogen
atmosphere. The reaction mixture was stirred for 5 days at room
temperature. The mixture was quenched with MeOH (0.1 mL)
and stirred for 1 h at room temperature. After being passed
through Celite, the filtrate was washed with sat. NaHCO3 aq.
and brine and then dried over anhydrous MgSO4. Removal of
the solvent gave a residue, which was purified by column
chromatography (n-hexane/EtOAc 7:1) to give 12a (206 mg, 68%)
as a colorless oil: 1H NMR (CDCl3) δ 7.40-7.26 (m, 20H), 4.97-
4.93 (m, 2H), 4.87-4.79 (m, 2H), 4.74-4.70 (m, 2H), 4.57 (d, 1H,
J ) 12 Hz), 4.49 (d, 1H, J ) 12 Hz), 4.41 (d, 1H, J ) 12 Hz),
4.10-3.94 (m, 7H), 3.75-3.70 (m, 1H), 3.56-3.44 (m, 3H), 1.62-
1.49 (m, 2H), 1.40-1.26 (m, 12H), 0.91 (t, 3H, J ) 6.6 Hz); 13C
NMR (CDCl3) δ 139.3, 139.1, 138.5, 128.8, 128.8, 128.7, 128.7,
128.7, 128.2, 128.1, 128.1, 128.0, 127.9, 108.6, 99.3, 79.1, 78.2,
77.0, 75.8, 75.7, 75.2, 73.9, 73.8, 73.3, 70.3, 70.0, 69.6, 60.3, 32.3,
29.7, 28.6, 26.7, 26.2, 23.0, 14.5; MS-ESI (m/z) 803 [M + Na]+;
HRMS-FAB (m/z) [M - N2]+ calcd for C46H57NO8, 751.4084,
found 751.4134.
(2S,3S,4R)-1-O-(r-D-Galactosyl)-2-tetracosanoylamino-
1,3,4-nonanetriol (1b). To a solution of 14 (89 mg, 81 µmol) in
MeOH (1.0 mL) and CH2Cl2 (5.0 mL) was added 4 M HCl aq. in
dioxane (100 µL) at 0 °C. After the mixture was stirred for 2 h
at room temperature, evaporation of the solvent gave a residue,
which was purified by column chromatography (CH2Cl2/MeOH
30:1) to give the product by which the acetal group was
deprotected. To a solution of the obtained diol in MeOH (3.0 mL)
and CHCl3 (1.0 mL) was added Pd(OH)2 (25 mg). After hydro-
genation was carried out for 3 h at atmospheric pressure, the
catalyst was filtered off and the filtrate was evaporated to give
1b (46 mg, 84%) as colorless crystals, mp 142-145 °C (recrystal-
(2S,3S,4R)-2-Azido-3,4-O-isopropylidene-1-O-(2,3,4,6-tetra-
O-benzyl-â-D-galactosyl)-1,3,4-nonanetriol (12b). To a sus-
pension of 10 (100 mg, 389 µmol), 11a (285 mg, 524 µmol), and
molecular sieves 4Å (powder, 400 mg) in dry CHCl3 (5 mL) was
added BF3‚Et2O (47 µL, 368 µmol) in dry CHCl3 (2 mL) at -50
°C under a nitrogen atmosphere. After stirring was continued
for 14 h at the same temperature, the workup in the same
manner for the reaction of 10 and 11b provided 12a (173 mg,
57%) along with 12b (76 mg, 25%) as a colorless oil. Data for
12b: 1H NMR (CDCl3) δ 7.38-7.23 (m, 20H), 4.96-4.90 (m, 2H),
4.83-4.61 (m, 4H), 4.46-4.39 (m, 3H), 4.12-4.04 (m, 2H), 3.92-
3.77 (m, 4H), 3.62-3.51 (m, 5H), 1.64-1.23 (m, 14H), 0.91 (t,
3H, J ) 6.3 Hz); 13C NMR (CDCl3) δ 138.9, 138.6, 138.5, 137.9,
128.5, 128.4, 128.3, 128.3, 128.2, 128.0, 127.9, 127.8, 127.6, 127.6,
127.6, 108.3, 104.1, 82.2, 79.7, 77.8, 75.8, 75.3, 74.6, 73.6, 73.6,
73.5, 73.1, 70.6, 68.7, 60.5, 31.9, 29.4, 28.2, 26.1, 25.7, 22.6, 14.1;
MS-ESI (m/z) 803 [M + Na]+; HRMS-FAB (m/z) [M - N2]+ calcd
for C46H57NO8, 751.4084, found 751.4005.
(2S,3S,4R)-2-Amino-3,4-O-isopropylidene-1-O-(2,3,4,6-
tetra-O-benzyl-r-D-galactosyl)-1,3,4-nonanetriol (13). To a
solution of 12a (2.58 g, 3.31 mmol) in EtOH (260 mL) was added
palladium on calcium carbonate poisoned with lead (Lindlar
catalyst) (2.60 g). After hydrogenation was carried out for 16 h
at atmospheric pressure, the catalyst was filtered off and the
filtrate was concentrated in vacuo to give 13 (2.46 g, quant) as
a colorless oil: 1H NMR (CDCl3) δ 7.40-7.25 (m, 20H), 4.96-
4.92 (m, 2H), 4.84-4.64 (m, 4H), 4.58 (d, 1H, J ) 11 Hz), 4.50
(d, 1H, J ) 12 Hz), 4.41 (d, 1H, J ) 12 Hz), 4.13-3.86 (m, 6H),
3.58-3.51 (m, 2H), 3.42-3.37 (m, 1H), 3.07-3.01 (m, 1H), 1.65-
1.20 (m, 14H), 0.90 (t, 3H, J ) 5.6 Hz); 13C NMR (CDCl3) δ 138.8,
138.7, 138.6, 138.0, 128.4, 128.4, 128.2, 127.8, 127.8, 127.7, 127.6,
127.6, 127.5, 127.4, 107.9, 99.0, 79.1, 79.0, 77.9, 74.9, 74.8, 73.5,
73.3, 73.0, 72.4, 69.5, 69.0, 50.7, 31.9, 29.8, 28.3, 26.0, 25.9, 22.6,
14.1; MS-ESI (m/z) 754 [M + H]+; HRMS-FAB (m/z) [M + H]+
calcd for C46H60NO8, 754.4319, found 754.4194.
lized from EtOH/H2O 10:1); [R]30 +53.9 (c 0.5, pyridine); 1H
D
NMR (CDCl3/CD3OD 3:1) δ 4.71 (d, 1H, J ) 3.8 Hz), 4.01-3.98
(m, 1H), 3.74-3.65 (m, 2H), 3.62-3.45 (m, 6H), 3.35-3.31 (m,
2H), 2.00 (t, 2H, J ) 7.6 Hz), 1.51-1.01 (m, 50H), 0.71-0.67
(m, 6H); 13C NMR (pyridine-d5) δ 173.8, 102.1, 77.3, 73.6, 73.0,
72.2, 71.6, 70.9, 69.2, 63.2, 52.0, 37.4, 34.9, 33.0, 32.7, 30.6, 30.6,
30.5, 30.4, 30.4, 30.3, 30.2, 27.0, 26.7, 23.6, 23.5, 14.8; MS-FAB
(m/z) 704 [M + H]+; HRMS-FAB (m/z) [M + H]+ calcd for
C
39H78NO9, 704.5677, found 704.5687. Anal. Calcd for C39H77-
NO9‚H2O: C, 64.87; H, 11.03; N, 1.94. Found: C, 64.71; H, 10.88;
N, 1.94.
Acknowledgment. We thank Mr. N. Takemoto, Ms.
M. Akabane, Mr. N. Ogou, and Ms. J. Futamura for
their contribution to the synthesis of related analogues.
We also thank Drs. T. Nishihara and G. Nakayama for
their support and encouragement throughout this study.
Note Added after ASAP Publication. As the result
of a production error, the formatting of the compound
names in the Experimental Section was inconsistent in
the version published ASAP February 16, 2005. These
have been corrected, and the solvent was changed in the
synthesis of 12b. The corrected version was published
February 18, 2005.
Supporting Information Available: 1H and/or 13C NMR
spectra of 1b, 3-10, 12a, 12b, 13, and 14. This material is
available free of charge via the Internet at http://pubs.acs.org.
(2S,3S,4R)-3,4-O-Isopropylidene-1-O-(2,3,4,6-tetra-O-ben-
zyl-r-D-galactosyl)-2-tetracosanoylamino-1,3,4-nonanetri-
ol (14). To a suspension of n-tetracosanoic acid (1.22 g, 3.31
mmol) in DMF (90 mL) and CH2Cl2 (210 mL) were added 1-ethyl-
3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDCI)
JO048151Y
J. Org. Chem, Vol. 70, No. 6, 2005 2401