Synthetic study on Campylobacter jejuni lipopolysaccharides: An improved synthesis of a branched, heptose-containing trisaccharide core structure and its conversion into ganglioside GD3 related hexasaccharide

Article abstract of DOI:10.1002/ejoc.200300309

The first synthesis of the oligosaccharide skeleton of the Campylobacter jejuni lipooligosaccharide composed of a branched, heptose-containing trisaccharide core structure and, including a substantially improved preparation of the core structure, the ganglioside GD3 related trisaccharide epitope is reported. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

Full text of DOI:10.1002/ejoc.200300309

FULL PAPER
Synthetic Study on Campylobacter jejuni Lipopolysaccharides: An Improved
Synthesis of a Branched, Heptose-Containing Trisaccharide Core Structure and
Its Conversion into Ganglioside GD3 Related Hexasaccharide[‡]
Koji Hori,[a] Naoki Sawada,[a] Hiromune Ando,[a] Hideharu Ishida,*[a] and Makoto Kiso*[a]
Keywords: Bioorganic chemistry / Ganglioside GD3 / Heptose / Natural products / Oligosaccharides / Carbohydrates
The first synthesis of the oligosaccharide skeleton of the
Campylobacter jejuni lipooligosaccharide composed of a
branched, heptose-containing trisaccharide core structure
and, including a substantially improved preparation of the
core structure, the ganglioside GD3 related trisaccharide
epitope is reported.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Introduction
attention has focused on the possibility that molecular
mimicry might be a factor in the pathogenesis of human
neurological disease.[4Ϫ6] The ganglioside-mimicking struc-
tures have been found to be located at the terminal regions
of the core oligosaccharides (OSs) of the LPS molecules.
OS structures mimicking human gangliosides GM2, GM1,
GD1a,[3,7] and GQ1b[6] have been found.
MillerϪFischer syndrome (MFS) is a neuropathy associ-
ated with ataxia, areflexia, and opthalmoplegia and is con-
sidered to be an infrequently occurring variation of the
´
more common form known as Guillain-Barre syndrome
(GBS).[2] Renewed interest in the etiology of these neuro-
pathies has stemmed from the finding that the onset of both
MFS and GBS in some patients is preceded by intestinal
infections with Campylobacter jejuni. It is known that lipo-
polysaccharides (LPSs) from some strains of C. jejuni mimic
the structures of human gangliosides (Figure 1),[3] and
In this study we describe an efficient construction of the
C. jejuni LPS mimicking the human ganglioside GD3,
which was recovered from a patient who developed MFS,[8]
as a part of the study to corroborate the molecular mimicry
hypothesis proposed for the onset of MFS and GBS.
Figure 1. Structure of lipooligosaccharide of Campylobacter jejuni PEN19 OH4382
[‡]
Synthetic Studies on Sialoglycoconjugates, 132. Part 131: Ref.[1]
Department of Applied Bioorganic Chemistry, Gifu University,
Gifu 501-1193, Japan
Results and Discussion
[a]
The main problems needing to be faced in the construc-
tion of the title compound 28 are: (i) the development of a
facile synthesis of -glycero--manno-heptose (-Hep; 8),
(ii) efficient construction of the branched, heptose-contain-
Fax:(internat.) ϩ 81-58/293-2840
E-mail: ishida@cc.gifu-u.ac.jp
kiso@cc.gifu-u.ac.jp
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
3752
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejoc.200300309
Eur. J. Org. Chem. 2003, 3752Ϫ3760

Synthetic Study on Campylobacter jejuni Lipopolysaccharides
FULL PAPER
ing trisaccharide core structure 26, and (iii) coupling of the sequent benzylation of alcohol 7 gave the suitably protected
core trisaccharide and GD3-related trisaccharide (see Fig- derivative of -Hep 8 (Scheme 1).
ure 2).
Our next objective was the efficient construction of the
A suitably protected -Hep derivative, in which the -Hep-containing trisaccharide core structure. Bernlind
hydroxy groups at C-1,3,4 are protected with different spec- and Oscarson[12] found that the preparation of branched
ies, was synthesized by the procedure described by Dasser trisaccharides with an α--linked moiety at an equatorial
et al.[9] Starting from known[10] 2-(trimethylsilyl)ethyl β-- O-3 position and a β--moiety at an equatorial O-4 posi-
mannopyranoside, 6-O-triphenylmethylation (94%), 2,3-O- tion was a difficult task, mainly due to steric crowding.
isopropylidenation
(87%),
4-O-p-methoxybenzylation They solved this problem by forming a 1,6-anhydro ring to
(95%), and the acidic hydrolysis of the triphenylmethyl change the conformation of the heptose ring of the acceptor
1
group with acetic acid/methanol (63%) gave the desired 6- from C1 to C. This approach succeeded in increasing the
OH derivative 4. Partial hydrolysis of the isopropylidene yield for the construction of the desired trisaccharide, but
group, affording the corresponding 2,3,6-OH derivative additional steps are required both to form the 1,6-anhydro
(37%), was observed under these conditions. This by-prod- bridge and later to cleave it. Our strategy is based on the
uct could be transformed into 4 (71%) after further isopro- use of the acetyl-protected disaccharide acceptor 20 as the
pylidenation, however. Swern oxidation[11] of the alcohol 4 key intermediate for the construction of the trisaccharide
gave the corresponding aldehyde, which was immediately structure, avoiding the presence of the bulkier benzoyl
condensed with commercially available vinylmagnesium groups used in the above work. Benzylation of 7 gave 8
bromide in tetrahydrofuran at Ϫ60 °C to afford alcohol 5 (97%), which was treated with DDQ[13] to give the desired
(82% in two steps). The stereochemistry at the new chiral -Hep acceptor 9 (93%). The -Hep donor 16, in which
center was determined by comparison of the NMR spectro- the hydroxy group at O-3 was protected as the correspond-
scopic data with those reported.[9] The allylic alcohol 5 was ing levulonate ester, was obtained from 9 in seven steps.
then protected as the benzyl ether 6 in 96% yield. The Compound 9 was benzylated (95%) and then treated with
double bond of 6 was oxidatively cleaved with sodium per- 85% aq. acetic acid to give the 2,3-diol derivative 11 (95%).
iodate in the presence of osmium tetraoxide in aqueous di- Phase-transfer-catalyzed benzylation[14] of 11 preferentially
ethyl ether. The intermediate aldehyde was immediately re- afforded the 2-O-benzylated derivative 12 (78%), which was
duced with sodium borohydride (71% in three steps). Sub- treated with levulinic acid, 4-(dimethylamino)pyridine, and
Scheme 1. Reagents: a) TrCl, DMAP/Pyr.; b) DMP, p-TsOH; c) MPMCl, NaH/DMF; d) AcOH; e) BnBr, NaH/DMF; f) (i) OsO4, NaIO4/
tBuOH, (ii) NaBH4/CH3OH, H2O; g) BnBr, NaH/DMF; h) DDQ, H2O/CH2Cl2; i) BnBr, NaH/DMF; j) 85% aq. AcOH; k) BnBr, TBAB/
10% aq. NaOH, (CH2Cl2); l) LevOH, DCC, DMAP/CH2Cl2; m) TFA/CH2Cl2; n) Ac2O/Pyr.; o) TMS·SMe, TMSOTf/CH2Cl2
Eur. J. Org. Chem. 2003, 3752Ϫ3760
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3753

K. Hori, N. Sawada, H. Ando, H. Ishida, M. Kiso
FULL PAPER
DCC to give 3-O-levulinoylated derivative 13 (99%). The 22 at O-2 (to give 23; 94%), the MPM group was removed
position protected with the levulinoyl group was confirmed by treatment with ceric ammonium nitrate (CAN) to afford
to be O-3 by NMR spectroscopic data [δ ϭ 5.31 ppm (dd, the desired Glcβ(1Ϫ4)-Hep glycosyl acceptor 24 (95%).
J2,3 ϭ 3.3, J3,4 ϭ 9.2 Hz, 1 H, 3-H)]. Compound 13 was The position protected with the benzoyl group was con-
converted into the methylthio derivative 16 by selective firmed to be O-2 by NMR spectroscopic data [δ ϭ 5.39
cleavage of the 2-(trimethylsilyl)ethyl group (to give 14; ppm (m, 1 H, 2a-H)]. NIS/TMSOTf-promoted coupling of
83%),[15] acetylation (to give 15; 98%), and treatment with 24 with suitably protected -Hep donor 16 gave the de-
trimethyl(methylthio)silane (TMS·SMe; 1:1 equiv.) and tri- sired α-linked trisaccharide 25 (54%). This result, in com-
methylsilyl trifluoromethanesulfonate at Ϫ10 °C (82%). It parison with the work of Bernlind and Oscarson com-
is worth mentioning that an increase in the amount of mented on above, underlines the importance of the choice
TMS·SMe or the reaction temperature resulted in decreased of the protecting groups, even in the residue next to the
yields, due to a concomitant side reaction involving the oxo residue to be glycosylated, for the outcome of glycosyl-
function in the levulinoyl group and the methylthio group ation reactions.
(Scheme 1). Alternatively, we also prepared the correspond-
The levulinoyl group in 25 was selectively removed by
ing trichloroacetimidate donor from 14, but this was too treatment with hydrazine monoacetate,[18] and the resulting
labile to be used as a glycosyl donor in our hands.
compound 26 was glycosylated with the trichloroacetimid-
Coupling of 9 with perbenzoylated glucosyl bromide ate[19] of the suitably protected disialylgalactose 27[20] in the
17[16] stereoselectively gave the β(1Ǟ4)-linked disaccharide presence of trimethylsilyl trifluoromethanesulfonate to af-
18 (89%), the benzoyl group of which was replaced with ford the desired hexasaccharide 28, in fully protected form
´
acetyl group by Zemplen transesterification (to give 19; (48%). Hexasaccharide 28 is a suitable precursor, after con-
99%) and conventional acetylation with acetic anhydride version into the corresponding glycosyl donor, for further
and pyridine (96%) to give 20. Removal of the isopropylid- coupling with KDO derivatives. Work in that direction is
ene acetal in 20 afforded the 2,3-diol 21 (96%), which was currently underway in our laboratory.
then glycosylated with 16 to give mainly the 2-O-glycosyl-
In conclusion, an improved synthesis of a branched, -
ated derivative (about 60%; data not shown). Tin acti- Hep-containing trisaccharide core structure was ac-
vation[17] of 21, followed by p-methoxybenzylation, gave 22 complished by appropriate manipulation of the protecting
(74%) as the major reaction product. After benzoylation of groups in Glcβ(1Ϫ4)-Hep glycosyl acceptor, and the ob-
Scheme 2. Reagents: a) CH3ONa/CH3OH; b) Ac2O/Pyr.; c) 80% aq. AcOH; d) (i) Bu2SnO/benzene, (ii) MPMCl, TBAB/benzene; e) BzCl/
Pyr.; f) CAN/CH3CN, H2O; g) NH2NH2·AcOH/CH3CH2OH
3754
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 3752Ϫ3760

Synthetic Study on Campylobacter jejuni Lipopolysaccharides
FULL PAPER
Figure 2. Synthetic plan for the title compound
2,3,4,5,6,6Ј-H), 4.82 (d, J1,2 ϭ 1.4 Hz, 1 H, 1-H), 7.20Ϫ7.50 (m, 15
H, 3 Ph). C30H38O6Si (522.71): calcd. C 68.93, H 7.33; found C
68.69, H 7.31.
tained trisaccharide was used as an efficient building block
in the construction of a ganglioside GD3 related hexasac-
charide.
2-(Trimethylsilyl)ethyl 2,3-O-Isopropylidene-6-O-trityl-α-D-manno-
pyranoside (2): A solution of 1 (1.83 g, 3.5 mmol) in 2,2-dimeth-
oxypropane (11 mL) was treated with p-toluenesulfonic acid
monohydrate (24 mg) and then stirred at room temperature. After
45 min, the solution was neutralized with triethylamine and ex-
tracted with chloroform. The organic layer was dried with anhy-
drous Na2SO4 and concentrated. The residue was chromato-
graphed on a column of silica gel (ethyl acetate/hexane, 1:5) to give
2 (1.72 g, 87%). [α]D ϭ ϩ0.74 (c ϭ 0.5, CHCl3). 1H NMR
(200 MHz, CDCl3): δ ϭ 0.02 (s, 9 H, Me3SiCH2CH2), 0.96 (m, 2
H, Me3SiCH2CH2), 1.33, 1.47 (2 s, 6 H, 2 CMe), 3.37 (m, 2 H, 6-
H, 6Ј-H), 3.5Ϫ4.0 (m, 4 H, Me3SiCH2CH2, 4-H, 5-H), 4.10 (m, 2
H, 2-H, 3-H), 5.01 (s, 1 H, 1-H), 7.1Ϫ7.5 (m, 15 H, 3 Ph).
C33H42O6Si (562.78): calcd. C 70.43, H 7.52; found C 70.16, H
7.26.
Experimental Section
General Remarks: Specific rotations were determined with a Horiba
SEPA-300 high-sensitivity polarimeter at ambient temperature
1
(25Ϯ1 °C ). H NMR spectra were recorded with Varian Gemini
2000 (200 MHz) and Varian Unity Inova (400 and 500 MHz) spec-
trometers with CDCl3 as solvent and TMS as the internal standard.
Preparative thin-layer chromatography (TLC) was performed on
silica gel 60 (E. Merck). Column chromatography on silica gel (Fuji
Silysia Co., 300 mesh) was performed with the solvent systems
specified (v/v). Concentrations and evaporations were conducted
in vacuo.
2-(Trimethylsilyl)ethyl 6-O-Trityl-α-
D-mannopyranoside (1): Trityl
chloride (1.3 g, 4.7 mmol) and 4-(dimethylamino)pyridine (50 mg)
2-(Trimethylsilyl)ethyl 2,3-O-Isopropylidene-4-O-(p-methoxy-
were added to a solution of 2-(trimethylsilyl)ethyl α--mannopyr- benzyl)-6-O-trityl-α-D-mannopyranoside (3): A solution of 2 (1.21 g,
anoside (1.1 g, 3.9 mmol) in pyridine (5 mL), and the mixture was
stirred at 40 °C for 24 h. After addition of methanol, the mixture
was stirred at room temperature for 30 min to quench the reaction
2.1 mmol) in DMF (9 mL) was treated with sodium hydride (65%;
135 mg, 3.6 mmol) at 0 °C for 30 min. p-Methoxybenzyl chloride
(0.32 mL, 2.3 mmol) was added at 0 °C to the mixture, which was
and concentrated. The residue was extracted with chloroform, and stirred at room temperature for 2 h. After addition of methanol,
the organic layer was washed with 2  HCl and sat. Na2CO3, and
dried with anhydrous Na2SO4. The solvent was evaporated, and
the residue was chromatographed on a column of silica gel (ethyl
the mixture was stirred for 30 min at room temperature and con-
centrated. The residue was extracted with diethyl ether, and the
organic layer was washed with water, dried with anhydrous
acetate) to give 1 (1.8 g, 89%). [α]D ϭ ϩ15.60 (c ϭ 0.5, CHCl3). Na2SO4, and concentrated. The residue was chromatographed on
1H NMR (200 MHz, CDCl3): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), a column of silica gel (ethyl acetate/hexane, 1:20) to give 3
0.95 (m, 2 H, Me3SiCH2CH2), 3.50Ϫ3.90 (m, 8 H, Me3SiCH2CH2, (1.39 g, 95%). 1H NMR (200 MHz, CDCl3): δ ϭ 0.00 (s, 9 H, Me3-
Eur. J. Org. Chem. 2003, 3752Ϫ3760
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3755

K. Hori, N. Sawada, H. Ando, H. Ishida, M. Kiso
FULL PAPER
SiCH2CH2), 0.96 (m, 2 H, Me3SiCH2CH2), 1.33, 1.47 (2 s, 6 H, 2 H, Me3SiCH2CH2), 3.56 (dd, J4,5 ϭ 9.8, J5,6 ϭ 1.6 Hz, 1 H, 5-H),
CMe), 3.17 (dd, J ϭ 5.9, J ϭ 9.8 Hz, 1 H, 6-H), 3.3Ϫ4.0 (m, 8 H, 3.75 (m, 1 H, Me3SiCH2CH2), 3.75 (s, 3 H, OMe), 3.86 (dd, J3,4
Me3SiCH2CH2, 4-H, 5-H, 6Ј-H, OMe), 3.77 (s, 3 H, OMe), 4.20 6.9, J4,5 ϭ 9.8 Hz, 1 H, 4-H), 4.05Ϫ4.35 (m, 5 H, 2-H, 3-H, 6-H,
(m, 1 H, 2-H), 4.26 (t, 1 H, 3-H), 4.26, 4.63 (d, 2 H, PhCH2), 5.19 PhCH2), 4.68, 4.76 (2 d, 2 H, PhCH2), 5.11 (s, 1 H, 1-H), 5.32 (m,
(s, 1 H, 1-H), 6.8Ϫ7.0 (m, 4 H, ArH), 7.1Ϫ7.5 (m, 15 H, 3 Ph). 2 H, 8-H, 8Ј-H), 6.7Ϫ7.4 (m, 9 H, ArH). C31H44O7Si (556.77):
ϭ
C41H50O7Si (682.93): calcd. C 72.11, H 7.38; found C 71.86, H
7.26.
calcd. C 66.87, H 7.97; found C 66.62, H 7.88.
2-(Trimethylsilyl)ethyl 6-O-Benzyl-2,3-O-isopropylidene-4-O-(p-
2-(Trimethylsilyl)ethyl 2,3-O-Isopropylidene-4-O-(p-methoxy-
methoxybenzyl)- -glycero-α- -manno-heptopyranoside (7): Water
L
D
benzyl)-α-
D
-mannopyranoside (4):
A
solution of
3
(109 mg,
(8 mL), osmium tetraoxide (2.5 wt% in tert-butyl alcohol,
1.59 mL), and sodium periodate (1.71 g, 8.0 mmol) were added to
a solution of 6 (890 mg, 1.6 mmol) in diethyl ether (8 mL), and the
0.15 mmol) in acetic acid (11 mL) was stirred at 60 °C for 11 h,
and then concentrated. The residue was diluted with chloroform,
and the organic layer was washed with sat. Na2CO3, dried with mixture was stirred at room temperature for 24 h. After evapor-
anhydrous Na2SO4, and concentrated. The residue was chromato-
graphed on a column of silica gel (ethyl acetate) to give 4 (43 mg,
ation of the solvent, the residue was dissolved in methanol (32 mL)
and water (16 mL). The solution was treated with sodium borohyd-
61%). [α]D ϭ ϩ55.7 (c ϭ 0.4, CHCl3). IR: ν˜ ϭ 3500 (OH), 2950 ride (242 mg, 6.4 mmol) at room temperature for 1 h, neutralized
(CH), and 860 and 840 (CϪSi) cmϪ1. 1H NMR (200 MHz, CDCl3): with 2  HCl, and then concentrated. The residue was extracted
δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), 0.89 (m, 2 H, Me3SiCH2CH2), with chloroform, and the organic layer was washed with water,
1.37, 1.51 (2 s, 6 H, 2 CMe), 3.4Ϫ3.9 (m, 6 H, Me3SiCH2CH2, 4-
H, 5-H, 6-H, 6Ј-H), 3.80 (s, 3 H, OMe), 4.12 (d, J2,3 ϭ 5.8 Hz, 1
dried with anhydrous Na2SO4, and concentrated. The residue was
chromatographed on a column of silica gel (ethyl acetate/hexane,
H, 2-H), 4.31 (t, 1 H, J2,3 ϭ J3,4 ϭ 6.2 Hz, 3-H), 4.55, 4.82 (d, 2 1:5) to give 7 (640 mg, 71%). [α]D ϭ ϩ58.7 (c ϭ 1.0, CHCl3). IR:
H, PhCH2), 5.20 (s, 1 H, 1-H), 6.8Ϫ7.3 (m, 4 H, ArH), 7.1Ϫ7.5 ν˜ ϭ 3500 (OH), 2950 (CH), 860 and 840 (CϪSi), and 740 and
(m, 15 H, 3 Ph). C22H36O7Si (440.61): calcd. C 59.97, H 8.24; found
C 59.88, H 8.12.
700 (phenyl) cmϪ1 1H NMR (200 MHz): δ ϭ 0.00 (s, 9 H,
.
Me3SiCH2CH2), 0.91 (m, 2 H, Me3SiCH2CH2), 1.38, 1.56 (2 s, 6
H, 2 CMe), 3.4Ϫ3.9 (m, 7 H, Me3SiCH2CH2, 4-H, 5-H, 6-H, 7-H,
7Ј-H), 3.75 (s, 3 H, OMe), 4.11 (d, J2,3 ϭ 5.8 Hz, 1 H, 2-H), 4.33
(t, 1 H, J2,3 ϭ J3,4 ϭ 5.8 Hz, 3-H), 4.25Ϫ4.9 (4 d, 4 H, 2 PhCH2),
5.09 (s, 1 H, 1-H), 5.32 (m, 2 H, 8-H, 8Ј-H), 6.7Ϫ7.3 (m, 9 H,
ArH). C30H44O8Si (560.76): calcd. C 64.26, H 7.91; found C 64.11,
H 7.74.
2-(Trimethylsilyl)ethyl
7,8-Dideoxy-2,3-O-isopropylidene-4-O-(p-
-manno-oct-7-enopyranoside (5): A
methoxybenzyl)- -glycero-α-
L
D
solution of oxalyl chloride (225 µL, 2.5 mmol) in THF (7 mL) was
cooled to Ϫ60 °C, and a solution of dimethyl sulfoxide (367 µL,
5.1 mmol) in THF (3 mL) was added. The reaction mixture was
stirred at room temperature for 5 min. A solution of 4 (950 mg,
2.1 mmol) in THF (7 mL) was added dropwise at Ϫ60 °C, and the
mixture was stirred at Ϫ60 °C for 15 min. A solution of triethyl-
2-(Trimethylsilyl)ethyl 6,7-Di-O-benzyl-2,3-O-isopropylidene-4-O-
(p-methoxybenzyl)-L-glycero-α-D-manno-heptopyranoside (8):
A
amine (1.5 mL, 10 mmol) in THF (3 mL) was added at Ϫ60 °C and solution of 7 (612 mg, 1.1 mmol) in DMF (12 mL) was treated with
the reaction mixture was allowed to warm to room temperature.
sodium hydride (65%, 68 mg, 1.8 mmol) and benzyl bromide (168
After completion of the reaction, the mixture was cooled to Ϫ60
µL, 1.4 mmol) as described for the p-methoxybenzylation of 2 to
°C again. Vinylmagnesium bromide (1.0  in THF, 10.7 mL, give 3. After the workup, the residue was chromatographed on a
10 mmol) was added, and the mixture was stirred at Ϫ60 °C for
24 h and then allowed to warm to room temperature. After ad-
dition of ethanol and sat. NH4Cl, the mixture was extracted with
column of silica gel (ethyl acetate/hexane, 1:10) to give 8 (689 mg,
97%). [α]D ϭ ϩ51.9 (c ϭ 1.8, CHCl3). IR: ν˜ ϭ 2950 (CH), 860 and
840 (CϪSi), and 740 and 700 (phenyl) cmϪ1. 1H NMR (200 MHz):
diethyl ether. The organic layer was washed with water, dried with δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), 0.90 (m, 2 H, Me3SiCH2CH2),
anhydrous Na2SO4, and concentrated. The residue was chromato- 1.41, 1.59 (2 s, 6 H, 2 CMe), 3.40Ϫ4.20 (m, 8 H, Me3SiCH2CH2,
graphed on a column of silica gel (ethyl acetate/hexane, 1:10) to 2-H, 4-H, 5-H, 6-H, 7-H, 7Ј-H), 3.78 (s, 3 H, OMe), 4.20Ϫ4.90 (6
give 5 (820 mg, 82%). [α]D ϭ ϩ27.0 (c ϭ 0.8, CHCl3). IR: ν˜ ϭ
d, 6 H, 3 PhCH2), 5.13 (s, 1 H, 1-H), 6.80Ϫ7.40 (m, 14 H, ArH).
C37H50O8Si (650.88): calcd. C 68.28, H 7.74; found C 68.21, H
1
3500 (OH), 2950 (CH), and 860 and 840 (CϪSi) cmϪ1. H NMR
(200 MHz, CDCl3): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), 0.89 (m, 2 7.61.
H, Me3SiCH2CH2), 1.36, 1.51 (2 s, 6 H, 2 CMe), 3.30Ϫ3.90 (m, 7
2-(Trimethylsilyl)ethyl 6,7-Di-O-benzyl-2,3-O-isopropylidene-
L-gly-
H, Me3SiCH2CH2, 4-H, 5-H), 3.78 (s, 3 H, OMe), 4.09 (d, J2,3
ϭ
cero-α- -manno-heptopyranoside (9): Water (0.45 mL) and 2,3-di-
D
5.8 Hz, 1 H, 2-H), 4.32 (t, 1 H, J2,3 ϭ J3,4 ϭ 6.2 Hz, 3-H), 4.43 (m,
1 H, 6-H), 4.55, 4.85 (d, 2 H, PhCH2), 5.02 (s, 1 H, 1-H), 5.18 (m,
1 H, 8-H), 5.34 (m, 1 H, 8Ј-H), 5.95 (m, 1 H, 7-H), 6.80Ϫ7.40 (m,
4 H, ArH). C22H36O7Si (440.61): calcd. C 61.77, H 8.21; found C
61.53, H 8.16.
chloro-5,6-dicyano-p-benzoquinone (DDQ; 470 mg, 2.0 mmol)
were added at 0 °C to a solution of 8 (900 mg, 1.3 mmol) in di-
chloromethane (9 mL), and the mixture was stirred at room tem-
perature for 1.5 h. Insoluble materials were removed by filtration
(Celite) and washed with chloroform. The filtrate and washings
were combined, washed with sat. Na2CO3, dried with Na2SO4, and
concentrated. The residue was chromatographed on a column of
silica gel (ethyl acetate/hexane, 1:5) to give 9 (685 mg, 93%). [α]D ϭ
2-(Trimethylsilyl)ethyl 6-O-Benzyl-7,8-dideoxy-2,3-O-isopropyl-
idene-4-O-(p-methoxybenzyl)-
L-glycero-α-D-manno-oct-7-eno-
pyranoside (6): A solution of 5 (118 mg, 0.25 mmol) in DMF
(3 mL) was treated with sodium hydride (65%, 15 mg, 0.42 mmol) ϩ35.8 (c ϭ 1.2, CHCl3). IR: ν˜ ϭ 3600Ϫ3500 (OH), 3100Ϫ2950
and benzyl bromide (39 µL, 0.32 mmol) as described for the p-
(CH), 860 and 840 (CϪSi), and 740 and 700 (phenyl) cmϪ1 1H
methoxybenzylation of 2, to give 3. After the workup, the residue NMR (400 MHz): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), 0.81Ϫ0.98
.
was chromatographed on a column of silica gel (ethyl acetate/hex-
ane, 1:20) to give 6 (136 mg, 96%). [α]D ϭ ϩ70.2 (c ϭ 1.0, CHCl3).
IR: ν˜ ϭ 2950 (CH), 860 and 840 (C-Si), and 740 and 700 (phenyl)
(m, 2 H, Me3SiCH2CH2), 1.36, 1.53 (2s, 6 H, Me2C), 2.13 (b, 1 H,
OH-4), 3.49 (m, 1 H, Me3SiCH2CH2), 3.65 (dd, J4,5 ϭ 10.3, J5,6
2.2 Hz, 1 H, 5-H), 3.73Ϫ3.82 (m, 4 H, Me3SiCH2CH2, 4-H, 7-H,
ϭ
cmϪ1. 1H NMR (400 MHz): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), 0.88 7Ј-H), 3.96 (dt, 1 H, J5,6 ϭ 2.2, J6,7 ϭ J6,7Ј ϭ 5.5 Hz, 6-H), 4.08
(m, 2 H, Me3SiCH2CH2), 1.38, 1.56 (2 s, 6 H, 2 CMe), 3.45 (m, 1 (m, 2 H, 2-H, 3-H), 4.54Ϫ4.86 (4 d, 4 H, 2 PhCH2), 5.08 (s, 1 H,
3756
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 3752Ϫ3760

Synthetic Study on Campylobacter jejuni Lipopolysaccharides
1-H), 7.28Ϫ7.41 (m, 10 H, ArH). C29H42O7Si (530.733): calcd. C (48 mL), and the mixture was stirred at room temperature for 1 h.
FULL PAPER
65.63, H 7.98; found C 65.37, H 7.68.
After addition of methanol, the mixture was stirred at room tem-
perature for 30 min, and then concentrated. The residue was chro-
matographed on a column of silica gel (ethyl acetate/hexane, 1:5)
to give 13 (5.5 g, 99%). [α]D ϭ ϩ24.0 (c ϭ 1.6, CHCl3). IR: ν˜ ϭ
3100Ϫ2800 (CH), 1730 (carbonyl), 860 and 840 (CϪSi), and 740
2-(Trimethylsilyl)ethyl 4,6,7-Tri-O-benzyl-2,3-O-isopropylidene-L-
glycero-α-D-manno-heptopyranoside (10): A solution of 9 (5.5 g,
10 mmol) in DMF (9 mL) was treated with sodium hydride (65%;
650 mg, 17 mmol) at 0 °C for 30 min. Benzyl bromide (2.0 mL,
17 mmol) was added at 0 °C to the mixture, which was stirred at
room temperature for 3 h. After addition of water, the mixture was
stirred at room temperature for 30 min. It was then diluted with
toluene and the organic layer was washed with water, dried with
anhydrous Na2SO4, and concentrated. The residue was chromato-
graphed on a column of silica gel (ethyl acetate/hexane, 1:10) to
give 10 (6.1 g, 95%). [α]D ϭ ϩ45.4 (c ϭ 0.9, CHCl3). IR: ν˜ ϭ
3100Ϫ2800 (CH), 860 and 840 (CϪSi), and 740 and 700 (phenyl)
cmϪ1. 1H NMR (400 MHz): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), 0.91
(m, 2 H, Me3SiCH2CH2), 1.40, 1.58 (2 s, 6 H, 2 CMe), 3.50 (m, 1
H, Me3SiCH2CH2), 3.72Ϫ3.86 (m, 5 H, Me3SiCH2CH2, 4-H, 5-H,
and 700 (phenyl) cmϪ1 1H NMR (400 MHz): δ ϭ 0.03 (s, 9 H,
.
Me3SiCH2CH2), 0.91 (m, 2 H, Me3SiCH2CH2), 2.12 (s, 3 H, MeC-
OCH2CH2), 2.34Ϫ2.68 (m, 4 H, MeCOCH2CH2), 3.47 (m, 1 H,
Me3SiCH2CH2), 3.72Ϫ3.79 (m,
2 H, Me3SiCH2CH2, 7Ј-H),
3.84Ϫ3.92 (m, 3 H, 2-H, 5-H, 7-H), 4.10 (t, J6,7 ϭ J6,7Ј ϭ 5.5 Hz,
1 H, 6-H), 4.21 (t, J3,4 ϭ J4,5 ϭ 9.2 Hz, 1 H, 4-H), 4.32Ϫ4.91 (8 d,
8 H, 4 PhCH2), 4.94 (d, J1,2 ϭ 1.8 Hz, 1 H, 1-H), 5.31 (dd, J2,3
ϭ
3.3, J3,4 ϭ 9.2 Hz, 1 H, 3-H), 7.20Ϫ7.42 (m, 20 H, ArH).
C45H56O9Si (769.018): calcd. C 70.28, H 7.34; found C 70.24, H
7.08.
2,4,6,7-Tetra-O-benzyl-3-O-levulinoyl-L-glycero-D-manno-hepto-
pyranose (14): Trifluoroacetic acid (28 mL) was added at 0 °C to a
solution of 13 (5.6 g, 7.2 mmol) in dichloromethane (56 mL), which
was stirred at 0 °C. After 3 h, the solution was concentrated. The
residue was chromatographed on a column of silica gel (ethyl acet-
ate/hexane, 1:2) to give 14 (4.0 g, 83%, α:β ϭ 10:1). IR: ν˜ ϭ
3600Ϫ3200 (OH), 3100Ϫ2800 (CH), 1730 (carbonyl), and 740 and
7-H, 7Ј-H), 4.14 (m, 2 H, 2-H, 6-H), 4.38 (t, 1 H, J2,3 ϭ J3,4
ϭ
5.8 Hz, 3-H), 4.30, 4.50Ϫ4.91 (6 d, 6 H, PhCH2), 5.14 (s, 1 H, 1-
H), 7.22Ϫ7.37 (m, 15 H, ArH). C36H48O7Si (620.857): calcd. C
69.65, H 7.79; found C 69.57, H 7.50.
2-(Trimethylsilyl)ethyl
4,6,7-Tri-O-benzyl-L-glycero-α-D-manno-
1
700 (phenyl) cmϪ1. H NMR (400 MHz) of α-form: δ ϭ 2.07 (s, 3
heptopyranoside (11): A solution of 10 (6.1 g, 9.8 mmol) in acetic
acid (60 mL) and water (10 min) was stirred at 50 °C for 24 h. After
concentration in vacuo, the residue was diluted with chloroform
and the organic layer was washed with sat. Na2CO3, dried with
anhydrous Na2SO4, and concentrated. The residue was chromato-
graphed on a column of silica gel (ethyl acetate/hexane, 1:3) to give
H, MeCOCH2CH2), 2.29Ϫ2.66 (m,
4 H, MeCOCH2CH2),
3.66Ϫ3.83 (m, 3 H, 2-H, 7-H, 7Ј-H), 3.97 (d, J4,5 ϭ 9.5 Hz, 1 H,
5-H), 4.02 (dd, J6,7 ϭ 6.2, J6,7Ј ϭ 5.9 Hz, 1 H, 6-H), 4.16 (dd, J3,4 ϭ
9.2, J4,5 ϭ 9.5 Hz, 1 H, 4-H), 4.28Ϫ4.82 (8 d, 8 H, 4 PhCH2), 5.19
(d, J1,2 ϭ 1.1 Hz, 1 H, 1-H), 5.31 (dd, J2,3 ϭ 2.9, J3,4 ϭ 8.8 Hz, 1
H, 3-H), 7.13Ϫ7.39 (m, 20 H, ArH). C40H44O9 (668.78): calcd. C
71.84, H 6.63; found C 71.75, H 6.37.
11 (5.5 g, 96%). [α]D ϭ ϩ80.5 (c ϭ 1.3, CHCl3). IR: ν˜
3600Ϫ3200 (OH), 3100Ϫ2800 (CH), 860 and 840 (CϪSi), and 740
and 700 (phenyl) cmϪ1 1H NMR (400 MHz): δ ϭ 0.00 (s, 9 H,
ϭ
.
1-O-Acetyl-2,4,6,7-tetra-O-benzyl-3-O-levulinoyl-L-glycero-α,β-D-
Me3SiCH2CH2), 0.88 (m, 2 H, Me3SiCH2CH2), 2.81 (broad s, 1 H,
OH-3), 3.23 (broad s, 1 H, OH-2), 3.43 (m, 1 H, Me3SiCH2CH2),
3.68Ϫ3.87 (m, 6 H, Me3SiCH2CH2, 2-H, 4-H, 5-H, 7-H, 7Ј-H),
3.85 (broad s, 1 H, 3-H), 4.14 (t, 1 H, J6,7 ϭ J6,7Ј ϭ 5.8 Hz, 6-H),
4.41Ϫ4.87 (d and m, 6 H, PhCH2), 4.83 (s, 1 H, 1-H), 7.24Ϫ7.38
(m, 15 H, ArH). C33H44O7Si (580.79): calcd. C 68.25, H 7.64; found
C 68.16, H 7.45.
manno-heptopyranose (15): Acetic anhydride (1 mL) was added to
a solution of 14 (470 mg, 0.7 mmol) in pyridine (5 mL) at 0 °C,
and the mixture was then stirred at room temperature for 24 h.
After addition of methanol at 0 °C, the solution was stirred for
30 min at room temperature, and then concentrated with toluene.
The residue was extracted with chloroform, and the organic layer
was washed with 2  HCl and water, dried with anhydrous Na2SO4,
and concentrated. The residue was chromatographed on a column
of silica gel (ethyl acetate/hexane, 1:3) to give 15 (490 mg, 98%, α/
β ϭ 10:1). IR: ν˜ ϭ 3100Ϫ2800 (CH), 1730 (carbonyl), and 740 and
2-(Trimethylsilyl)ethyl 2,4,6,7-Tetra-O-benzyl-L-glycero-α-D-manno-
heptopyranoside (12): NaOH (10% aq., 30 mL), benzyl bromide
(2.4 mL, 20 mmol), and tetrabutylammonium bromide (1.3 g,
4.0 mmol) were added to a solution of 11 (5.9 g, 10 mmol) in 1,2-
dichloroethane (36 mL), and the mixture was stirred at 50 °C for
24 h. The mixture was extracted with chloroform, and the organic
layer was washed with water, dried with anhydrous Na2SO4, and
concentrated. The residue was chromatographed on a column of
1
700 (phenyl) cmϪ1. H NMR (500 MHz) of α-form: δ ϭ 1.95 (s, 3
H, AcO), 2.10 (s, 3 H, MeCOCH2CH2), 2.34Ϫ2.65 (m, 4 H, MeC-
OCH2CH2), 3.64 (dd, J6,7Ј ϭ 6.6, J7,7Ј ϭ 9.6 Hz, 1 H, 7-H), 3.81
(dd, J6,7Ј ϭ 6.2, J7,7Ј ϭ 9.6 Hz, 1 H, 7Ј-H), 3.85 (m, 1 H, 2-H), 3.93
(d, J4,5 ϭ 9.8 Hz, 1 H, 5-H), 4.05 (t, J6,7 ϭ J6,7Ј ϭ 6.2 Hz, 1 H, 6-
H), 4.25 (dd, J3,4 ϭ 9.2, J4,5 ϭ 9.6 Hz, 1 H, 4-H), 4.34Ϫ4.81 (8 d,
8 H, 4 PhCH2), 5.25 (dd, J2,3 ϭ 3.2, J3,4 ϭ 9.2 Hz, 1 H, 3-H), 6.18
(d, J1,2 ϭ 1.8 Hz, 1 H, 1-H), 7.12Ϫ7.42 (m, 20 H, ArH). C42H46O10
(710.82): calcd. C 70.97, H 6.52; found C 70.72, H 6.42.
silica gel (ethyl acetate/hexane, 1:5) to give 12 (5.3 g, 78%). [α]D
ϩ20.6 (c ϭ 1.8, CHCl3). IR: ν˜ ϭ 3600Ϫ3300 (OH), 3100Ϫ2800
(CH), 860 and 840 (CϪSi), and 740 and 700 (phenyl) cmϪ1 1H
ϭ
.
NMR (400 MHz): δ ϭ 0.05 (s, 9 H, Me3SiCH2CH2), 0.88 (m, 2 H,
Me3SiCH2CH2), 2.39 (d, JOH,3 ϭ 9.9 Hz, 1 H, OH-3), 3.47 (m, 1
H, Me3SiCH2CH2), 3.71Ϫ3.78 (m, 4 H, Me3SiCH2CH2, 2-H, 5-H,
7Ј-H), 3.86Ϫ3.92 (m, 2 H, 4-H, 7-H), 4.04 (m, 1 H, 3-H), 4.17 (m,
1 H, 6-H), 4.36Ϫ4.91 (8 d, 8 H, 4 PhCH2), 5.03 (d, J1,2 ϭ 1.1 Hz,
1 H, 1-H), 7.25Ϫ7.41 (m, 20 H, ArH). C40H50O7Si (670.92): calcd.
C 71.61, H 7.51; found C 71.40, H 7.36.
Methyl 2,4,6,7-Tetra-O-benzyl-3-O-levulinoyl-1-thio-
manno-heptopyranoside (16): Trimethyl(methylthio)silane (26 µL,
0.18 mmol) and trimethylsilyl trifluoromethanesulfonate
L-glycero-α-D-
(TMSOTf; 32 µL, 0.16 mmol) were added at Ϫ10 °C to a solution
of 15 (119 mg, 0.16 mmol) in dichloromethane (2 mL). The reac-
tion mixture was diluted with chloroform, and the organic layer
was washed with sat. Na2CO3, dried with anhydrous Na2SO4, and
2-(Trimethylsilyl)ethyl 2,4,6,7-Tetra-O-benzyl-3-O-levulinoyl-
L-gly-
cero-α-D-manno-heptopyranoside (13): Levulinic acid (1.5 mL, concentrated. The residue was chromatographed on a column of
14 mmol), 4-(dimethylamino)pyridine (DMAP; 175 mg, 1.4 mmol),
and 1,3-dicyclohexylcarbodiimide (DCC; 2.9 g, 14 mmol) were ad-
ded to a solution of 12 (4.8 g, 7.1 mmol) in dichloromethane
silica gel (ethyl acetate/hexane, 1:3) to give 16 (96 mg, 82%). [α]D ϭ
ϩ43.1 (c ϭ 1.0, CHCl3). IR: ν˜ ϭ 3100Ϫ2800 (CH), 1730 (car-
bonyl), and 740 and 700 (phenyl) cmϪ1. 1H NMR (500 MHz): δ ϭ
Eur. J. Org. Chem. 2003, 3752Ϫ3760
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3757

K. Hori, N. Sawada, H. Ando, H. Ishida, M. Kiso
FULL PAPER
2.05 (s, 3 H, MeS), 2.10 (s, 3 H, MeCOCH2CH2), 2.36Ϫ2.64 (m, 4 and 840 (CϪSi), and 740 and 700 (phenyl) cmϪ1
H, MeCOCH2CH2), 3.70 (dd, J6,7 ϭ 5.9, J7,7Ј ϭ 9.6 Hz, 1 H, 7- (400 MHz): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), 0.88 (m, 2 H, Me3S-
H), 3.82 (dd, J6,7Ј ϭ 6.4, J7, 7Ј ϭ 9.8 Hz, 1 H, 7Ј-H), 3.91 (dd, J1,2 ϭ iCH2CH2), 1.34, 1.52 (2 s, 6 H, Me2C), 1.98Ϫ2.07 (4 s, 12 H, 4
.
1H NMR
2.7, J2,3 ϭ 2.9 Hz, 1 H, 2-H), 4.07 (dt, J5,6 ϭ 1.4, J6,7 ϭ J6,7Ј
6.2 Hz, 1 H, 6-H), 4.12 (dd, J4,5 ϭ 9.6, J5,6 ϭ 1.1 Hz, 1 H, 5-H),
4.19 (dd, J3,4 ϭ 8.7, J4,5 ϭ 9.4 Hz, 1 H, 4-H), 4.29Ϫ4.84 (d and m,
ϭ
AcO), 2.86 (m, 1 H, 5b-H), 3.49 (m, 1 H, Me3SiCH2CH2),
3.70Ϫ3.79 (m, 3 H, Me3SiCH2CH2, 5a-H, 7a-H), 3.88Ϫ4.04 (m, 4
H, 4a-H, 6a-H, 6b-H, 7a-H), 4.08 (d, J2,3 ϭ 5.5 Hz, 1 H, 2a-H),
8 H, PhCH2), 5.19 (dd, J2,3 ϭ 3.2, J3,4 ϭ 8.5 Hz, 1 H, 3-H), 5.28 4.13 (dd, J5,6Ј ϭ 4.4, J6,6Ј ϭ 12.1 Hz, 1 H, 6Јb-H), 4.30 (d, J1,2
ϭ
(d, J1,2 ϭ 2.9 Hz, 1 H, 1-H), and 7.17Ϫ7.38 (m, 20 H, ArH). 7.3 Hz, 1 H, 1b-H), 4.31 (t, J2,3 ϭ J3,4 ϭ 5.5 Hz, 1 H, 3a-H),
C41H46O8S (698.87): calcd. C 70.46, H 6.63; found C 70.40, H 6.52.
2-(Trimethylsilyl)ethyl (2,3,4,6-Tetra-O-benzoyl-β- -glucopyrano-
4.52Ϫ4.59 (3 d, 3 H, PhCH2), 4.92 (m, 4 H, 2b-H, 3b-H, 4b-H,
PhCH2), 5.10 (s, 1 H, 1a-H), 7.28Ϫ7.45 (m, 10 H, ArH).
C43H60O16Si (861.02): calcd. C 59.98, H 7.02; found C 59.85, H
6.83.
D
syl)-(1Ǟ4)-6,7-di-O-benzyl-2,3-O-isopropylidene- -glycero-α-D-
L
manno-heptopyranoside (18): A solution of 17 (1.39 g, 2.1 mmol)
and 9 (625 mg, 1.1 mmol) in dichloromethane (15 mL) was stirred
in the presence of 2,4,6-trimethylpyridine (248 µL, 1.8 mmol) and
2-(Trimethylsilyl)ethyl (2,3,4,6-Tetra-O-acetyl-β-
D-glucopyranosyl)-
(1Ǟ4)-6,7-di-O-benzyl- -glycero-α- -manno-heptopyranoside (21):
L
D
˚
molecular sieves (4 A; 2.0 g) at room temperature for 1 h and then
Compound 20 (810 mg, 0.94 mmol) was treated with acetic acid
(8 mL) and water (2 mL) as described for the synthesis of 11. After
the workup, the residue was chromatographed on a column of silica
cooled to
0 °C. Silver trifluoromethanesulfonate (595 mg,
2.3 mmol) was added to the mixture at 0 °C in the dark, and the
system was stirred in the dark at 0 °C for 24 h. After addition of
triethylamine for neutralization, insoluble materials were removed
by filtration (Celite) and washed with chloroform. The filtrate and
washings were combined and concentrated to a syrup, which was
chromatographed on a column of silica gel (ethyl acetate/hexane,
gel (ethyl acetate/hexane, 1:2) to give 21 (741 mg, 96%). [α]D
ϭ
ϩ61.9 (c ϭ 1.2, CHCl3). IR: ν˜ ϭ 3650Ϫ3200 (OH), 3100Ϫ2800
(CH), 1760 and 1240 (ester), 860 and 840 (C-Si), and 740 and 700
(phenyl) cmϪ1 1H NMR (500 MHz): δ ϭ 0.00 (s, 9 H, Me3S-
.
iCH2CH2), 0.86, 0.94 (m, 2 H, Me3SiCH2CH2), 2.01Ϫ2.11 (4 s, 12
1:3) to give 18 (1.1 g, 89%). [α]D ϭ ϩ24.7 (c ϭ 1.34, CHCl3). IR: H, 4 AcO), 3.24 (m, 1 H, 5b-H), 3.47 (m, 1 H, Me3SiCH2CH2),
ν˜ ϭ 3100Ϫ2800 (CH), 1730 and 1260 (ester), 860 and 840 (CϪSi), 3.66Ϫ3.94 (m, 8 H, Me3SiCH2CH2, 2a-H, 3a-H, 4a-H, 5a-H, 6a-
and 740 and 700 (phenyl) cmϪ1. 1H NMR (400 MHz): δ ϭ 0.00 (s, H, 7a-H, 7Јa-H), 4.07 (dd, J5,6 ϭ 5.5, J6,6Ј ϭ 12.4 Hz, 1 H, 6b-H),
9 H, Me3SiCH2CH2), 0.79Ϫ0.98 (m, 2 H, Me3SiCH2CH2), 1.29, 4.18 (dd, J5,6Ј ϭ 2.9, J6,6Ј ϭ 12.4 Hz, 1 H, 6Јb-H), 4.30 (d, J1,2
1.55 (2 s, 6 H, Me2C), 3.47 (m, 2 H, Me3SiCH2CH2, 5b-H), 3.66 8.0 Hz, 1 H, 1b-H), 4.52Ϫ4.57 (3 d, 3 H, PhCH2), 4.85Ϫ5.01 (m,
(dd, J6,7 ϭ 5.5, J7,7Ј ϭ 9.5 Hz, 1 H, 7a-H), 3.69Ϫ3.80 (m, 3 H, 5 H, 1a-H, 2b-H, 3b-H, 4b-H, PhCH2), 7.28Ϫ7.48 (m, 10 H, ArH).
ϭ
Me3SiCH2CH2, 5a-H, 7Јa-H), 4.03 (t, J6,7 ϭ J6,7Ј ϭ 5.5 Hz, 1 H, C40H56O16Si (820.96): calcd. C 58.52, H 6.88; found C 58.46, H
6a-H), 4.07Ϫ4.13 (m, 2 H, 2a-H, 4a-H), 4.37Ϫ4.50 (m, 5 H, 3a-H, 6.81.
6b-H, PhCH2), 4.56 (dd, J6,6Ј ϭ 11.7 Hz, 1 H, 6b-H), 4.83 (d, J1,2 ϭ
8.1 Hz, 1 H, 1b-H), 4.82Ϫ4.86 (4 d, 3 H, 2 PhCH2), 5.11 (s, 1 H,
2-(Trimethylsilyl)ethyl (2,3,4,6-Tetra-O-acetyl-β-
(1Ǟ4)-6,7-di-O-benzyl-3-O-(p-methoxybenzyl)-
manno-heptopyranoside (22): A solution of 21 (358 mg, 0.43 mmol)
D
-glucopyranosyl)-
L
-glycero-α-D-
1a-H), 5.60 (dd, J1,2 ϭ 8.1, J2, ϭ 9.9 Hz, 1 H, 2b-H), 5.65 (t,
3
J3,4 ϭ 9.5, J4,5 ϭ 9.9 Hz, 1 H, 4b-H), 5.78 (t, J2,3 ϭ 9.9, J3, 4
ϭ
in benzene (7 mL) was stirred in the presence of molecular sieves
9.5 Hz, 1 H, 3b-H), 7.25Ϫ8.06 (m, 30 H, ArH). C63H68O16Si
(1109.37): calcd. C 68.21, H 6.18; found C 68.06, H 5.98.
˚
(4 A; 0.7 g) at room temperature for 1 h, and dibutyltin oxide
(217 mg, 0.86 mmol) was added. After the system had been stirred
under reflux for 12 h, tetrabutylammonium bromide (140 mg,
0.43 mmol) and p-methoxybenzyl chloride (118 µL, 0.86 mmol)
were added, and the mixture was stirred under reflux for an ad-
ditional 6 h. Insoluble materials were removed by filtration (Celite),
2-(Trimethylsilyl)ethyl (β-
benzyl-2,3-O-isopropylidene-
D
-Glucopyranosyl)-(1Ǟ4)-6,7-di-O-
L
-glycero-α- -manno-heptopyranoside
D
(19): Sodium methoxide was added to a solution of 18 (1.1 g,
0.99 mmol) until pH ϭ 12, and the mixture was stirred at room
temperature for 24 h. After neutralization with Amberlite IR 120 and washed with chloroform. The filtrate and washings were com-
(Hϩ), the resin was removed by filtration and washed with meth-
anol. The filtrate and washings were combined and concentrated
to syrup, which was chromatographed on a column of silica gel
bined and concentrated to a syrup, which was chromatographed on
a column of silica gel (ethyl acetate/hexane, 1:3) to give 22 (307 mg,
74%). [α]D ϭ ϩ45.6 (c ϭ 1.8, CHCl3). IR: ν˜ ϭ 3650Ϫ3200 (OH),
(ethyl acetate/hexane, 5:1) to give 19 (673 mg, 98%). [α]D ϭ ϩ7.1 3100Ϫ2800 (CH), 1760 and 1240 (ester), 860 and 840 (CϪSi), and
(c ϭ 1.0, CHCl3). IR: ν˜ ϭ 3700Ϫ3100 (OH), 3100Ϫ2800 (CH), 860
740 and 700 (phenyl) cmϪ1 1H NMR (500 MHz): δ ϭ 0.00 (s, 9
and 840 (C-Si), and 740 and 700 (phenyl) cmϪ1 1H NMR H, Me3SiCH2CH2), 0.87 (m, 2 H, Me3SiCH2CH2), 1.96Ϫ2.00 (4 s,
.
.
(500 MHz): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), 0.88 (m, 2 H, Me3S-
iCH2CH2), 1.35, 1.50 (2 s, 6 H, Me2C), 2.92 (t, J5,6 ϭ 6.9 Hz, 1 H,
12 H, 4 AcO), 2.79 (m, 1 H, 5b-H), 3.43 (m, 1 H, Me3SiCH2CH2),
3.64Ϫ3.73 (m, 4 H, Me3SiCH2CH2, 3a-H, 5a-H, 7Јa-H), 3.79 (s, 3
H, MeO), 3.83 (broad d, 1 H, 2a-H), 3.87Ϫ3.94 (m, 2 H, 6Јb-H,
7a-H), 4.04Ϫ4.13 (m, 4 H, 1b-H, 4a-H, 6a-H, 6b-H), 4.48Ϫ4.74 (5
5b-H), 3.48 (m, 1 H, Me3SiCH2CH2), 3.58 (dd, J5,6 ϭ 6.9, J6,6Ј
ϭ
11.4 Hz, 1 H, 6b-H), 4.07 (d, J2,3 ϭ 6.2 Hz, 1 H, 2a-H), 4.13 (m, 1
H, 6a-H), 4.36 (t, J2,3 ϭ J3,4 ϭ 6.2 Hz, 1 H, 3a-H), 4.49Ϫ4.89 (4 d, 5 H, PhCH2), 4.84Ϫ4.99 (m, 5 H, 1a-H, 2b-H, 3b-H, 4b-H,
d, 4 H, 2 PhCH2), 7.25Ϫ7.38 (m, 10 H, ArH). C35H52O12Si PhCH2), 6.82Ϫ7.44 (m, 14 H, ArH). C48H64O17Si (941.11): calcd.
(692.88): calcd. C 60.67, H 7.56; found C 60.51, H 7.57.
C 61.26, H 6.85; found C 61.12, H 6.72.
2-(Trimethylsilyl)ethyl (2,3,4,6-Tetra-O-acetyl-β- -glucopyranosyl)-
D
2-(Trimethylsilyl)ethyl (2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl)-
(1Ǟ4)-6,7-di-O-benzyl-2,3-O-isopropylidene- -glycero-α- -manno-
heptopyranoside (20): Compound 19 (685 mg, 0.95 mmol) was
treated with pyridine (7 mL) and acetic anhydride (0.8 mL, 0.22 mmol) was added at 0 °C to a solution of 22 (110 mg,
L
D
(1Ǟ4)-2-O-benzoyl-6,7-di-O-benzyl-3-O-(p-methoxybenzyl)-
L-
glycero-α- -manno-heptopyranoside (23): Benzoyl chloride (26 µL,
D
7.7 mmol) as described for the synthesis of 15. After the workup,
0.11 mmol) in pyridine (2 mL), and the mixture was stirred for 8 h
the residue was chromatographed on a column of silica gel (ethyl
at room temperature. After addition of methanol at 0 °C, the mix-
acetate/hexane, 1:3) to give 20 (817 mg, 99%). [α]D ϭ ϩ15.6 (c ϭ ture was concentrated with toluene. The residue was extracted with
1.0, CHCl3). IR: ν˜ ϭ 3100Ϫ2800 (CH), 1760 and 1220 (ester), 860 chloroform, and the organic layer was washed with 2  HCl and
3758
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 3752Ϫ3760

Synthetic Study on Campylobacter jejuni Lipopolysaccharides
FULL PAPER
water, dried with anhydrous Na2SO4, and concentrated. The resi-
due was chromatographed on a column of silica gel (ethyl acetate/
H, 1c-H), 5.42 (dd, J1,2 ϭ 1.8, J2,3 ϭ 2.9 Hz, 2a-H), 7.15Ϫ8.11 (m,
35 H, ArH). C87H102O25Si (1575.83): calcd. C 66.31, H 6.52; found
hexane, 1:2) to give 23 (114 mg, 94%). [α]D ϭ Ϫ22.4 (c ϭ 1.8, C 66.15, H 6.48.
CHCl3). IR: ν˜ ϭ 3100Ϫ2800 (CH), and 1760 and 1240 (ester), 860
and 840 (CϪSi), and 740 and 700 (phenyl) cmϪ1 1H NMR
.
2-(Trimethylsilyl)ethyl (2,4,6,7-Tetra-O-benzyl-
manno-heptopyranosyl)-(1Ǟ3)-[(2,3,4,6-tetra-O-acetyl-β-
glucopyranosyl)-(1Ǟ4)]-2-O-benzoyl-6,7-di-O-benzyl- -glycero-α-
L
-glycero-α-
D
-
-
-
(400 MHz): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2), 0.89 (m, 2 H, Me3S-
iCH2CH2), 1.75Ϫ1.99 (4 s, 12 H, 4 AcO), 2.89 (m, 1 H, 5b-H), 3.47
(m, 1 H, Me3SiCH2CH2), 3.68Ϫ3.82 (m, 7 H, Me3SiCH2CH2, 5a-
H, 6Јb-H, 7Јa-H, MeO), 3.89 (m, 2 H, 3a-H, 7a-H), 4.00 (dd, 1 H,
6b-H), 4.11Ϫ4.19 (m, 2 H, 1b-H, 6a-H), 4.29 (t, 1 H, 4a-H),
4.50Ϫ4.63 (6 d, 6 H, 3 PhCH2), 4.90Ϫ4.96 (m, 4 H, 1a-H, 2b-H,
3b-H, 4b-H), 5.46 (m, 1 H, 2a-H), 6.77Ϫ8.06 (m, 19 H, ArH).
C55H68O18Si (1045.22): calcd. C 63.20, H 6.56; found C 62.99, H
6.34.
D
L
D
manno-heptopyranoside (26): Hydrazine acetate (69 mg, 0.72 mmol)
was added to a solution of 25 (115 mg, 72 µmol) in ethanol (2 mL),
which was stirred at room temperature for 2 h and concentrated.
The residue was extracted with chloroform, and the organic layer
was washed with water, dried with anhydrous Na2SO4, and concen-
trated. The residue was chromatographed on a column of silica gel
(ethyl acetate/hexane, 1:2) to give 26 (80 mg, 74%). [α]D ϭ Ϫ16.5
(c ϭ 1.6, CHCl3). IR: ν˜ ϭ 3650Ϫ3400 (CH), 3100Ϫ2800 (CH),
1760 and 1220 (ester), 860 and 840 (CϪSi), and 740 and 700 (phe-
nyl) cmϪ1. 1H NMR (500 MHz): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2),
0.94 (m, 2 H, Me3SiCH2CH2), 1.69Ϫ2.03 (4 s, 12 H, 4 AcO), 2.31
(d, JOH,3 ϭ 9.2 Hz, 1 H, OH-3), 2.58 (m, 1 H, 5b-H), 3.48 (m, 1
H, Me3SiCH2CH2), 3.69Ϫ4.24 (m, 15 H, 1b-H, 2c-H, 3c-H, 4c-H,
5a-H, 5c-H, 6a-H, 6b-H, 6Јb-H, 6c-H, 7a-H, 7Јa-H, 7c-H, 7Јc-H),
4.23 (dd, J2,3 ϭ 2.9, J3,4 ϭ 9.4 Hz, 3a-H), 4.37 (t, J3,4 ϭ 9.8, J4,5 ϭ
9.6 Hz, 4a-H), 4.42 (d, 1 H, PhCH2), 4.54Ϫ4.61 (6 d, 6 H, 3
PhCH2), 4.69Ϫ4.92 (m, 7 H, 2b-H, 3b-H, 4b-H, PhCH2), 4.93 (d,
J1,2 ϭ 1.4 Hz, 1 H, 1a-H), 5.14 (d, 1 H, PhCH2), 5.33 (s, 1 H, 1c-
H), 5.42 (dd, J1,2 ϭ 1.8, J2,3 ϭ 2.9 Hz, 2a-H), 7.22Ϫ8.09 (m, 35 H,
ArH). C82H96O23Si (1477.73): calcd. C 66.65, H 6.55; found C
66.50, H 6.29.
2-(Trimethylsilyl)ethyl (2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl)-
(1Ǟ4)-2-O-benzoyl-6,7-di-O-benzyl- -glycero-α-
L
D
-manno-
heptopyranoside (24): Diammonium cerium() nitrate (CAN;
151 mg, 0.27 mmol) was added to a solution of 23 (96 mg, 91 µmol)
in a mixture of acetonitrile (2.7 mL) and water (0.3 mL), and the
mixture was stirred at room temperature for 1 h. The mixture was
extracted with chloroform, and the organic layer was washed with
sat. NaHCO3 and water, dried with anhydrous Na2SO4, and con-
centrated. The residue was chromatographed on a column of silica
gel (ethyl acetate/hexane, 1:3) to give 24 (80 mg, 95%). [α]D ϭ ϩ9.7
(c ϭ 1.8, CHCl3). IR: ν˜ ϭ 3600Ϫ3400 (OH), 3100Ϫ2800 (CH),
1760 and 1220 (ester), 860 and 840 (CϪSi), and 740 and 700 (phe-
nyl) cmϪ1. 1H NMR (500 MHz): δ ϭ 0.00 (s, 9 H, Me3SiCH2CH2),
0.99 (m, 2 H, Me3SiCH2CH2), 1.71Ϫ2.03 (4 s, 12 H, 4 AcO), 3.23
(m, 1 H, 5b-H), 3.47 (m, 1 H, Me3SiCH2CH2), 3.60 (s, 1 H, OH-
3), 3.67Ϫ3.75 (m, 3 H, Me3SiCH2CH2, 3a-H, 7Јa-H), 3.84 (t, J3,4 ϭ
J4,5 ϭ 9.4 Hz, 4a-H), 3.88Ϫ3.93 (m, 3 H, 6a-H, 6b-H, 7a-H),
4.01Ϫ4.07 (m, 2 H, 3a-H, 6b-H), 4.50Ϫ4.58, 5.04 (4 d, 4 H, 2
PhCH2), 4.80Ϫ4.87 (m, 2 H, 2b-H, 4b-H), 4.93Ϫ4.96 (m, 2 H, 1a-
H, 3b-H), 5.39 (m, 1 H, 2a-H), 7.24Ϫ8.08 (m, 15 H, ArH).
C47H60O17Si (925.07): calcd. C 61.02, H 6.54; found C 60.77, H
6.46.
2-(Trimethylsilyl)ethyl [Methyl 5-acetamido-8-O-(5-acetamido-
4,7,8,9-tetra-O-acetyl-3,5-dideoxy-
nonulopyranosylono-1,9-lactone)-4,7-di-O-acetyl-3,5-dideoxy-
glycero-α-
benzoyl-β-
glycero-α-
β- -glucopyranosyl)-(1Ǟ4)]-2-O-benzoyl-6,7-di-O-benzyl-
α- -manno-heptopyranoside (28): A solution of 26 (61 mg, 41 µmol)
D-glycero-α-D-galacto-2-
D
-
D
-galacto-2-nonulopyranosylonate]-(2Ǟ3)-(2,4,6-tri-O-
D
-galactopyranosyl)-(1Ǟ3)-(2,4,6,7-tetra-O-benzyl-L
-
D
-manno-heptopyranosyl)-(1Ǟ3)-[(2,3,4,6-tetra-O-acetyl-
-glycero-
D
L
D
2-(Trimethylsilyl)ethyl
glycero-α- -manno-heptopyranosyl)-(1Ǟ3)-[(2,3,4,6-tetra-O-acetyl-
β- -glucopyranosyl)-(1Ǟ4)]-2-O-benzoyl-6,7-di-O-benzyl- -glycero-
α- -manno-heptopyranoside (25):
0.31 mmol) and 24 (178 mg, 0.19 mmol) in dichloromethane (2 mL) were removed by filtration (Celite) and washed with chloroform.
(2,4,6,7-Tetra-O-benzyl-3-O-levulinoyl-
L-
and 27 (106 mg, 72 µmol) in dichloromethane (2 mL) was stirred
D
at room temperature for 2 h in the presence of molecular sieves (4
A; 0.8 g). TMSOTf (2.6 µL, 14 µmol) was added to the mixture,
˚
D
L
D
A solution of 16 (222 mg, which was stirred at room temperature for 24 h. Insoluble materials
was stirred at room temperature for 2 h in the presence of molecu-
lar sieves (4 A; 1 g). After the mixture had been cooled to Ϫ50 °C,
The filtrate and washings were combined and washed with sat.
NaHCO3, dried with anhydrous Na2SO4, and concentrated. The
˚
N-iodosuccinimide (NIS; 86 mg, 0.38 mmol) and TMSOTf (4 µL, residue was chromatographed on a column of silica gel (chloro-
19 µmol) were added, and the mixture was stirred at Ϫ50 °C for
24 h. Insoluble materials were removed by filtration (Celite) and
washed with chloroform. The filtrate and washings were combined
and diluted with chloroform, and the organic layer was washed
with sat. Na2CO3 and sat. Na2S2O3, dried with anhydrous Na2SO4,
and concentrated. The residue was chromatographed on a column
form/methanol, 50:1) to give 28 (55 mg, 48%). [α]D ϭ Ϫ23.6 (c ϭ
1.3, CHCl3). IR: ν˜ ϭ 3700Ϫ3100 (NH), 3100Ϫ2800 (CH), 1740
and 1240 (ester), 1680Ϫ1540 (amide), 860 and 840 (CϪSi), and 740
and 700 (phenyl) cmϪ1 1H NMR (500 MHz): δ ϭ 0.07 (s, 9 H,
.
Me3SiCH2CH2), 0.89 (m, 2 H, Me3SiCH2CH2), 1.61 (m, 1 H, 3fax-
H), 1.70Ϫ2.11 (12 s, 36 H, 10 AcO, 2 AcN), 1.87 (m, 1 H, 3eax-
of silica gel (ethyl acetate/hexane, 2:3) to give 25 (116 mg, 54%). H), 2.02 (m, 1 H, 3eeq-H), 2.45 (dd, Jgem ϭ 13.5, J3,4 ϭ 5.3 Hz, 1
[α]D ϭ Ϫ19.2 (c ϭ 1.2, CHCl3). IR: ν˜ ϭ 3100Ϫ2800 (CH), 1760
H, 3feq-H), 2.86 (m, 1 H, 5b-H), 3.25 (s, 3 H, MeO), 3.40 (m, 1
H, Me3SiCH2CH2), 3.51 (bd, 1 H, 9Јe-H), 3.64 (m, 1 H, Me3S-
and 1220 (ester), 860 and 840 (CϪSi), and 740 and 700 (phenyl)
cmϪ1. 1H NMR (500 MHz): δ ϭ 0.07 (s, 9 H, Me3SiCH2CH2), 0.89 iCH2CH2), 3.83 (dd, J5,6 ϭ 10.5, J6,7 ϭ 2.9 Hz, 1 H, 6f-H), 4.36
(m, 2 H, Me3SiCH2CH2), 1.54Ϫ2.04 (5 s, 15 H, 4 AcO, MeC-
OCH2CH2), 2.21Ϫ2.53 (m, 4 H, MeCOCH2CH2), 2.58 (m, 1 H, 3d-H, 4b-H, PhCH2), 4.74Ϫ4.81 (m, 4 H, 1a-H, 1d-H, 7e-H,
5b-H), 3.43, 3.67 (m, 2 H, Me3SiCH2CH2), 3.72Ϫ4.14 (m, 12 H, PhCH2), 4.94 (t, J2,3 ϭ J3,4 ϭ 9.4 Hz, 3b-H), 5.06 (m, 1 H, 4e-H),
(m, 1 H, 4a-H), 4.43 (d, 1 H, PhCH2), 4.49Ϫ4.67 (m, 11 H, 2b-H,
1b-H, 2c-H, 5a-H, 5c-H, 6a-H, 6b-H, 6Јb-H, 6c-H, 7a-H, 7Јa-H, 5.11Ϫ5.16 (m, 3 H, 8f-H, PhCH2), 5.27Ϫ5.33 (m, 4 H, 1c-H, 7f-
7c-H, 7Јc-H), 4.22Ϫ4.36 (m, 3 H, 3a-H, 4a-H, 4c-H), 4.39 (d, 1 H, H, 5e-NH, 5f-NH), 5.40 (s, 1 H, 2a-H), 5.53Ϫ5.59 (m, 2 H, 2d-H,
PhCH2), 4.50Ϫ4.74 (m, 11 H, 2b-H, 4b-H, PhCH2), 4.84Ϫ4.88 (m, 4f-H), 5.63(d, J3,4 ϭ 2.7 Hz, 4d-H), 6.83Ϫ8.08 (m, 50 H, ArH).
2 H, 3b-H, PhCH2) 4.89 (d, J1,2 ϭ 1.6 Hz, 1 H, 1a-H), 5.10 (d, 1 C144H164N2O52Si (2782.95): calcd. C 62.15, H 5.94; found C 61.98,
H, PhCH2), 5.18 (dd, J2,3 ϭ 2.9, J3,4 ϭ 10.1 Hz, 3c-H), 5.29 (s, 1
H 5.80.
Eur. J. Org. Chem. 2003, 3752Ϫ3760
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3759

K. Hori, N. Sawada, H. Ando, H. Ishida, M. Kiso
FULL PAPER
Nan Shin, L. A. Kurjanczyk, J. L. Penner, Infect. Immun. 1996,
64, 2945Ϫ2949.
M. Dasser, F. Chretin, Y. Chapleur, J. Chem. Soc., Perkin
Acknowledgments
[9]
´
This study was supported in part by Grants-in-Aid (nos. 12306007
and 10660107) for Scientific Research from the Ministry of
Education, Culture, Sports, Science, and Technology Japan, and
Japan Society for Promotion of Science. We thank Ms. Kiyoko Ito
for technical assistance.
Trans. 1 1990, 3091Ϫ3094.
[10]
[11]
V. Posgay, Tetrahedron Lett. 1993, 34, 7175Ϫ7178.
A. J. Mancuso, D. S. Brownfrain, D. Swern, J. Org. Chem.
1979, 44, 4148Ϫ4150.
[12]
[13]
C. Bernlind, S. Oscarson, J. Org. Chem. 1998, 63, 7780Ϫ7788.
K. Horita, T. Yoshioka, T. Tanaka, Y. Okikawa, O. Yonemitsu,
Tetrahedron 1986, 42, 3201Ϫ3208.
P. J. Garegg, I. Kvarnström, A. Niklasson, G. Niklasson, S. C.
T. Svensson, J. Carbohydr. Chem. 1993, 12, 933Ϫ953.
K. Jansson, S. Ahlfors, T. Frejd, J. Kihlberg, G. Magnusson, J.
Dahmen, G. Noori, K. Stenvall, J. Org. Chem. 1988, 53,
5629Ϫ5647.
R. K. Ness, H. G. Fletcher, Jr., C. S. Hudson, J. Am. Chem.
Soc. 1950, 72, 2200Ϫ2205.
S. David, S. Hanessian, Tetrahedron 1985, 41, 643Ϫ663.
H. J. Koeners, J. Verhoeven, J. H. van Boom, Recl. Trav. Chim.
Pays-Bas 1981, 100, 65Ϫ72.
[1]
[14]
[15]
A. Ishihara, H. Ishida, T. Ikami, N. Tomiya, H. Ando, M.
Kiso, J. Carbohydr. Chem., accepted.
A. H. Ropper, New Engl. J. Med. 1992, 326, 1130Ϫ1136.
G. O. Aspinall, A. G. McDonald, T. S. Raju, H. Pang, S. D.
[2]
[3]
Mills, L. A. Kurjanczyk, J. L. Penner, J. Bacteriol. 1992, 174,
[16]
1324Ϫ1332.
[4]
S. Fujimoto, N. Yuki, T. Itoh, K. Amako, J. Infect. Dis. 1992,
165, 183.
G. O. Aspinall, S. Fujimoto, A. G. McDonald, H. Pang, L. A.
[17]
[18]
[5]
Kurjanczyk, J. L. Penner, Infect. Immun. 1994, 62, 2122Ϫ2125.
N. Yuki, T. Taki, M. Takahashi, K. Saito, H. Yoshino, T. Tai,
[6]
[19]
[20]
R. R. Schmidt, Angew. Chem. 1986, 98, 213Ϫ236; Angew.
Chem. Int. Ed. Engl. 1986, 25, 212Ϫ235.
S. Handa, T. Miyatake, Ann. Neurol. 1994, 36, 791Ϫ793.
G. O. Aspinall, A. G. McDonald, H. Pang, L. A. Kurjanczyk,
[7]
H.-K. Ishida, Y. Ohta, Y. Tsukada, M. Kiso, A. Hasegawa,
Carbohydr. Res. 1993, 246, 75Ϫ88.
J. L. Penner, Biochemistry 1994, 33, 241Ϫ249.
S. Salloway, L. A. Mermel, M. Seamans, G. O. Aspinall, J. E.
[8]
Received May 19, 2003
3760
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 3752Ϫ3760