A convenient synthetic route to mannose 6-phosphonate-cholesteryl conjugate

Article abstract of DOI:10.1002/hc.10134

The synthesis of mannose 6-phosphonate-based glycolipid was discussed. The synthesis involved a one-carbon chain elongation at the 6-position of mannose, followed by phosphonation, using tris(trimethylsilyl) phosphite. The final step of synthesis involved an Arbuzov reaction between the alkyl bromide derivative and tris(trimethylsilyl) phosphite, followed by deprotection of the acetate under Zemplen conditions.

Full text of DOI:10.1002/hc.10134

Heteroatom Chemistry
Volume 14, Number 3, 2003
A Convenient Synthetic Route to Mannose
6-Phosphonate–Cholesteryl Conjugate
Se´bastien Vidal, Alain More`re, and Jean-Louis Montero
Laboratoire de Chimie Biomole´culaire (UMR 5032), Universite´ Montpellier II, ENSCM,
8 Rue de l’Ecole Normale, 34296—Montpellier Cedex 05, France
Received 26 September 2002
complex [3]. We recently [4] demonstrated that an
ABSTRACT: A multistep synthesis of a mannose 6-
amphiphilic steroidal mannose 6-phosphonate can
phosphonate-based glycolipid is described involving
be incorporated into the liposome lipidic bilayer
(1) a one-carbon chain elongation at the 6-position
and that the resulting “functionalized” vesicle in-
of mannose, followed by (2) phosphonation, using
teracted strongly with MCF-7 breast cancer cells
tris(trimethylsilyl)phosphite. This method was shown
(overexpressing the M6P/IGFIIR), demonstrating
to be efficient and provides a general route to various
the high potential of such system for drug delivery
mannose 6-phosphonate-based compounds for the de-
applications.
ꢀ
C
sign of drug delivery systems. 2003 Wiley Periodicals,
However, during the preparation of M6Pn/CSA
Inc. Heteroatom Chem 14:241–246, 2003; Published online
[4] (where M6Pn and CSA stands for mannose 6-
in Wiley InterScience (www.interscience.wiley.com). DOI
phosphonate and CholesterylSuccinylAnilinyl, re-
10.1002/hc.10134
spectively) used in that investigation, we observed
(Fig. 1) partial degradation of this molecule, using
Rabinowitz’s procedure [5] for the deprotection of
the diethylphosphonate (using Me3SiBr), and par-
tial cleavage of the anomeric bond and/or amide
bond(s).
It is worth pointing out that similar degrada-
tion problems have been described previously for
aminoacids [6] or carbohydrate [7] frameworks.
We therefore decided to prepare a modified am-
phiphilic M6Pn compound in which the hydrophilic
carbohydrate head will be linked to the hydrophobic
steroidal tail through a triethyleneglycol (TEG)
moiety (Fig. 1).
INTRODUCTION
Lectins are involved in a wide variety of biological
functions such as cell–cell communication, virus–
cell, toxin–cell, or bacterium–cell interactions, all of
which occur through lectin–carbohydrate recogni-
tion at the cell surface [1]. As part of our ongoing
work, we focus on one lectin target from the P-type
family, namely, the Mannose 6-Phosphate/Insulin-
like II Receptor (M6P/IGFIIR). This 300 kDa type I
transmembrane glycoprotein was shown [2] to bind
Mannose 6-Phosphate (M6P)-bearing glycoproteins
with high affinity (ꢀM–nM range) and then internal-
ize them through endocytosis of the receptor–ligand
RESULTS AND DISCUSSION
We decided to use the Arbuzov phosphonation as the
key step to introduce the phosphonate moiety at the
very end of our synthetic scheme. This approach al-
lowed us to use tris(trimethylsilyl)phosphite, which
reacts with an alkyl halide derivative affording bis-
silylated phosphonates, which are easily hydrolyzed
Correspondence to: Alain More`re; e-mail: morere@univ-
montp2.fr.
Contract grant sponsor: Scientific Council of the Universite´
Montpellier II.
Contract grant sponsor: Fondation pour la Recherche Me´dicale.
Contract grant sponsor: Mayoly-Spindler Laboratories.
2003 Wiley Periodicals, Inc.
c
ꢀ
241

242 Vidal, More`re, and Montero
FIGURE 1 Partial degradations of M6Pn/CSA observed and
structure of the target glycolipid M6Pn/TEGC.
to the corresponding phosphonic acids through mild
basic hydrolysis with saturated NaHCO3(aq) during
the reaction work-up.
This new strategy requires a one-carbon chain
elongation at the 6-position of mannose to obtain the
alkyl halide intermediate. This mannose derivative
was therefore prepared through (1) a cautiously se-
lected one-carbon chain elongation method and (2)
a glycosylation reaction.
The synthesis of the M6Pn/TEGC was accom-
plished as outlined in Scheme 1. Many studies
have been performed concerning the one-carbon
chain elongation of various alcohols [8]. From these
methods, we decided to use a one-carbon chain elon-
gation at the 6-position of benzyl 2,3,4-tri-O-benzyl-
α-D-mannopyranoside [9] (1) through triflate activa-
tion of the primary alcohol followed by substitution
[10] with 2-lithio-1,3-dithiane affording compound
2 in 80% yield over both steps.
SCHEME 1 Preparation of the M6Pn/TEGC. Reagents and
conditions: (i) Tf2O, CH2Cl2, 2,6-di-t-butyl-4-methylpyridine,
−10◦C to r.t., 5 min; (ii) 1,3-dithiane, THF, n-BuLi, HMPA,
−78◦C to r.t., 10 min, 80% over both steps; (iii) CH3I,
CH3CN/H2O (11:2), CaCO3, 50◦C,
3 h; (iv) NaBH4,
EtOH/H2O (1:1), r.t., 10 min, 90% over both steps; (v) H2,
THF/H2O/AcOH (50:50:1), Pd(OH)2/C (20%), r.t., 24 h, 98%;
(vi) TsCl, C5H5N, r.t., 5 h; (vii) Ac2O, C5H5N, 0◦C to r.t., 12 h;
(viii) LiBr, butanone, 85◦C, 1 h, 45% over three steps; (ix)
HBr/AcOH, CH2Cl2, r.t., 16 h; (x) 8-(cholest-5-en-3β-yloxy)-
3,6-dioxaoctan-1-ol, CH2Cl2, AgOTf, sym-collidine, 0◦C to r.t.,
15 min, 45% over both steps; (xi) TMSOTf, CH2Cl2, m◦olecular
◦
˚
sieves (3 A), −5 C, 5 min, 40%; (xii) P(OSiMe3)3, 60 C, 16 h
then NaHCO3(aq); (xiii) NaOMe, MeOH, r.t., 16 h, 55% over
both steps.
The dithioacetal 2 was subsequently unmasked
to the aldehyde [11] (not isolated), which was re-
duced to furnish the homologated mannoheptose
derivative 3 in 90% yield over both steps. This four-
step procedure could be performed rapidly since
each reaction in the synthetic scheme only takes
5–10 min and only one purification step is neces-
sary, i.e., purification of the 1,3-dithianyl derivative
2. Hydrogenolysis of 3, using a catalytic amount of
acetic acid [12] to aid in the deprotection of the
anomeric center, afforded the deprotected 6-deoxy-D-
mannoheptose 4. Next, we had to functionalize the
pyranose ring to allow (1) the introduction of the
steroidal moiety via glycosylation and (2) the phos-
phonation reaction to obtain the final amphiphilic
phosphonate. Thus, compound 4 was first activated
at the 7-position, using tosyl chloride in pyridine fol-
lowed by in situ peracetylation of the pyranose ring
[13] and subsequent bromination utilizing lithium
bromide in refluxing butanone [14], affording com-
pound 5 in 45% yield over three steps. The poor
yield obtained for this one-pot synthesis is probably
a consequence of the low solubility of compound 4 in
pyridine. Koenigs–Knorr glycosylation [15] of 5, us-
ing known 8-(cholest-5-en-3β-yloxy)-3,6-dioxaoctan-
1-ol [16] as the glycosyl acceptor, affords the or-
thoester derivative 6 as the major product, which
upon subsequent treatment with a Lewis acid un-
derwent rearrangement [17] to furnish the desired
glycoside 7.
The final step in our synthesis involved an
Arbuzov reaction between the alkyl bromide deriva-
tive 7 and tris(trimethylsilyl)phosphite, followed by
deprotection of the acetate under Zemple´n con-
ditions affording the final M6Pn/TEGC in good
yields.

A Convenient Synthetic Route to Mannose 6-Phosphonate–Cholesteryl Conjugate 243
Benzyl 6-Deoxy-6-(2ꢁ-dithianyl)-2,3,4-tri-O-
CONCLUSION
benzyl-α-D-mannopyranoside (2)
In summary, we have demonstrated that a new
route to steroidal M6Pn is possible through (1)
one-carbon chain elongation at the 6-position
of mannose, followed by (2) phosphonation us-
ing the tris(trimethylsilyl)phosphite under Arbuzov
conditions. Preparation of liposomes incorporat-
ing M6Pn/TEGC and evaluation of their interac-
tions with MCF-7 cells are now being investi-
gated in our group with the aim of developing
a new drug delivery system. Although the over-
all yield is still low (1.9% over 18 steps starting
from D-mannose), this strategy provides a general
route to a wide variety of functionalized M6Pn
where the anomeric center will be substituted
with any biologically active molecule during the
glycosylation.
To a cooled (−10◦C) solution of benzyl 2,3,4-tri-O-
benzyl-6-deoxy-α-D-mannopyranoside (1) [9] (3.29 g,
6.08 mmol) and 2,6-di-tert-butyl-4-methylpyridine
(1.56 g, 7.6 mmol) in CH2Cl2 (20 ml) was added
triflic anhydride (1.79 ml, 6.7 mmol). The reaction
mixture was stirred at r.t. for 10 min then neutral-
ized with NaHCO3(aq) (200 ml, 0.1 g/l) and the aque-
ous layer was extracted with CH2Cl2 (3 × 300 ml).
Organic layers were combined, dried (Na2SO4), fil-
tered, and evaporated under reduced pressure. The
crude triflate was used for next step without fur-
ther purification. To a cooled (−78◦C) solution of
1,3-dithiane (2.56 g, 21.29 mmol) in THF (20 ml)
was added HMPA (1.06 ml, 6.08 mmol). Next, n-
BuLi (5 ml, 21.29 mmol, 1.6 M in hexanes) was
added dropwise. After 10 min, a solution of triflate
dissolved in THF (30 ml) was added dropwise, and
after a further 10 min, the reaction was neutral-
ized with NH4Cl(aq) (200 ml, 0.1 g/l) and the aque-
ous layer extracted with CH2Cl2 (2 × 300 ml). Or-
ganic layers were combined, dried (Na2SO4), filtered,
and evaporated under reduced pressure. The residue
was purified by silica gel column chromatography
(light petroleum/ether 4:1) affording 2 (2.87 g, 80%).
Rf = 0.50 (light petroleum/ether 7:3). [α]20D + 31.0◦
(c 0.72, CHCl3). 1H NMR (CDCl3): δ = 1.80–2.20 (m,
EXPERIMENTAL
General Methods
Analytical TLC were performed using aluminum-
coated TLC plates 60-F254 (Merck). Plates were devel-
oped with (1) UV light (254 nm), and (2) immersion
in a 10% H2SO4/EtOH solution followed by charring
or (3) immersion in a 5% Rhodanine/EtOH solu-
tion followed by charring (for aldehydes), or (4) im-
mersion in a phosphomolybdic solution (for phos-
phorus containing compounds). Silica gel column
chromatography was performed with silica gel 60A
(Carlo Erba). Optical rotations were measured at the
sodium D-line with a Perkin–Elmer-241 polarime-
ter. IR Spectra were obtained on Perkin–Elmer FT-
1600 spectrometer in CH2Cl2 solutions. Fast Atom
Bombardment (FAB) mass spectra were recorded
on a Jeol JMS-DX300 spectrometer in either posi-
tive (>0) or negative (<0) modes and using either 3-
nitrobenzylic alcohol (NBA) or glycerol/thioglycerol
(1:1) mixture (G/T). 1H NMR Spectra were recorded
on a Bru¨ker DRX 400 (400 MHz), at 25◦C. Chem-
ical shifts (δ) are given in ppm and referenced us-
ing residual solvent signals (7.24 ppm for CHCl3
and 4.79 ppm for HOD). The following abbrevia-
tions were used to explain the signal multiplicities
or characteristics: s (singlet), d (doublet), dd (dou-
ble doublet), t (triplet), td (triplet doublet), m (mul-
tiplet). 13C NMR Spectra were recorded on a Bru¨ker
DRX 400 (100.6 MHz). Chemical shifts (δ) are given
3H, H-6a and CH CH2S), 2.35–2.55 (m, 1H, H-6b),
2
2.65–2.90 (m, 4H, CH2CH S), 3.76 (t, 1H, J = 9.4 Hz,
2
H-4), 3.86 (dd, 1H, J = 1.9, 3.0 Hz, H-2), 4.00 (dd,
1H, H-3), 4.10 (td, 1H, J = 2.3, 9.4 Hz, H-5), 4.38
(dd, 1H, J = 4.0, 11.1 Hz, H-7), 4.45 (d, 1H, J =
11.5 Hz, CH Phanom), 4.65 (s, 2H, CH Ph), 4.69 (d,
2
2
1H, J = 10.9 Hz, CH Ph), 4.73 (d, 1H, J = 12.4 Hz,
2
CH Ph), 4.81 (d, 1H, CH Ph), 4.90 (d, 1H, CH Phanom),
2
2
2
4.92 (d, 1H, H-1), 5.00 (d, 1H, CH Ph), 7.30–7.45 (m,
2
20H, H-ar). 13C NMR (CDCl3): δ = 26.5 (CH2CH2S),
29.7, 30.3 (CH2CH2S), 38.2 (C-6), 43.8 (C-7), 68.6–
80.7 (C-2, C-3, C-4, and C-5), 69.4 (CH2Phanom), 72.7,
73.3, 75.9 (CH2Ph), 97.4 (C-1), 128.0–129.4 (CH-
ar), 137–137.5 (Cquat-ar). MS FAB > 0 (NBA): m/z =
589 (M)+, 551 (M-CH2Ph)+, 535 (M-OCH2Ph)+,
443 (M-OCH2Ph-CH2Ph)+, 91 (CH2Ph)+. Anal for
C38H42O5S2: Calcd: C 71.00, H 6.59; Found: C 71.28,
H 6.64.
Benzyl 6-Deoxy-2,3, 4-tri-O-benzyl-α-D-manno-
heptopyranoside (3)
in ppm relative to TMS as an external reference. 31
P
NMR Spectra were recorded on a Bru¨ker DPX 200
(81.0 MHz). Chemical shifts (δ) are given in ppm
relative to phosphoric acid (85%) as an external
reference.
To a solution of 2 (1 g, 1.56 mmol) dissolved
in CH3CN/H2O (52 ml, 11:2) was added calcium
carbonate (470 mg, 4.67 mmol) and methyl iodide

244 Vidal, More`re, and Montero
(2.15 ml, 34.3 mmol). The reaction was heated (50◦C)
for 3 h then neutralized with saturated Na2S2O3(aq)
(100 ml). The aqueous layer was extracted with
EtOAc (2 × 100 ml), and the organic layers com-
bined, dried (Na2SO4), filtered, and evaporated un-
der reduced pressure. The crude product was dis-
solved in absolute ethanol (25 ml) and a solution
of sodium borohydride (148 mg, 3.89 mmol), dis-
solved in EtOH/H2O (25 ml, 1:1) was added drop-
wise. The reaction was neutralized with 1 M HCl
to pH ≈ 6. The reaction mixture was then diluted
with H2O (150 ml), and the aqueous layer ex-
tracted with EtOAc (5 × 100 ml). The organic lay-
ers were combined, dried (Na2SO4), filtered, and
evaporated under reduced pressure. The residue
was purified by silica gel column chromatography
(light petroleum/ether 3:7) affording 3 (778 mg,
7-Bromo-6,7-dideoxy-1,2,3,4-tri-O-acetyl-α-D-
manno-heptopyranoside (5)
To a solution of 4 (730 mg, 3.76 mmol) in C5H5N
(50 ml) was added tosyl chloride (1.08 g, 5.64 mmol).
Reaction was stirred for 5 h, then Ac2O (7.2 ml,
75.26 mmol) was added to the cooled (0◦C) reaction
mixture. After 12 h, the reaction was diluted with
brine (125 ml) and the aqueous layer extracted with
CH2Cl2 (3 × 150 ml). The organic layers were com-
bined, dried (Na2SO4), filtered, and evaporated un-
der reduced pressure, utilizing toluene (3 × 100 ml)
to coevaporate C5H5N. The crude product was dis-
solved in butanone (20 ml) and lithium bromide
(1 g, 11.5 mmol) added. The reaction was heated
(85◦C) for 1 h then diluted with brine (100 ml).
The aqueous layer was extracted with CH2Cl2 (3 ×
100 ml) and the organic layers were combined, dried
(Na2SO4), filtered, and evaporated under reduced
pressure. The resulting residue was purified by silica
gel column chromatography (light petroleum/ether
9:1) affording 5 (716 mg, 45%). Rf = 0.61 (light
petroleum/ether 3:7) 1H NMR (CDCl3): δ = 1.80–2.00
90%). Rf = 0.44 (light petroleum/ether 3:7). [α]20
+
D
54.9◦ (c 1.02, CHCl3). IR (NaCl): ν = 3460. 1H
NMR (CDCl3): δ = 1.80–2.00 (m, 1H, H-6a), 2.10–
2.30 (m, 1H, H-6b), 3.75–4.05 (m, 6H, H-2, H-
3, H-4, H-5, H-7a, and H-7b), 4.46 (d, 1H, J =
11.8 Hz, CH Ph), 4.66 (s, 2H, CH Ph), 4.67 (d, 1H,
2
2
(m, 2H, H-6a and H-6b), 2.00 (s, 3H, CH CO), 2.07
3
J = 10.8 Hz, CH Phanom), 4.71 (d, 1H, J = 12.4 Hz,
2
(s, 3H, CH CO), 2.15 (s, 3H, CH CO), 3.40–3.70 (m,
3
3
CH Ph), 4.72 (d, 1H, CH Ph), 4.80 (d, 1H, CH Ph)
2
2
2
2H, H-7a and H-7b), 4.08 (td, 1H, J = 3.0, 9.9 Hz, H-
5), 5.16 (t, 1H, H-4), 5.26 (dd, 1H, J = 1.8, 3.5 Hz,
H-2), 5.34 (dd, 1H, H-3), 5.99 (d, 1H, H-1). 13C
NMR (CDCl3): δ = 20.9–21.2 (CH3CO), 29.2 (C-7),
33.9 (C-6), 68.4–69.6 (C-2, C-3, C-4, and C-5), 90.6
(C-1), 170.1, 170.2, 170.3, 170.4 (CH3CO). MS
FAB > 0 (NBA): m/z = 447 (M + Na)+, 365 (M-OAc)+,
345 (M-Br)+, 245 (M-2OAc-2H)+, 203 (M-2OAc-
CH3CO-H)+, 43 (CH3CO)+. Anal for C15H21BrO9:
Calcd: C 42.37, H 4.95; Found: C 42.29, H 4.92.
4.89 (d, 1H, J = 1.6 Hz, H-1), 5.01 (d, 1H, CH Phanom),
2
7.20–7.45 (m, 20H, H-ar). 13C NMR (CDCl3): δ =
34.2 (C-6), 61.5 (C-7), 69.4 (CH2Phanom), 72.2–80.6
(C-2, C-3, C-4, and C-5), 72.6, 73.3, 75.8 (CH2Ph),
97.5 (C-1), 128.0–128.9 (CH-ar), 137.5–138.8 (Cquat
-
ar). MS FAB > 0 (NBA): m/z = 577 (M + Na)+, 553
(M-H)+, 447 (M-OCH2Ph)+, 91 (CH2Ph)+. Anal for
C35H38O6: Calcd: C 75.79, H 6.91; Found: C 75.96,
H 6.95.
6-Deoxy-α-D-manno-heptopyranose (4)
7-Bromo-6,7-dideoxy-2,3,4-tri-O-acetyl-1,2-O-
[8-(cholest-5-en-3β-yloxy)-3,6-dioxaoctan-1-
yloxyethylidene]-β-D-manno-heptopyranose (6)
A solution of 3 (4.44 g) and Pd(OH)2/C (20%, 2.5 g)
in THF/H2O (100 ml, 1:1) and glacial acetic acid
(5 ml) was vigorously stirred under a hydrogen at-
mosphere for 24 h. The reaction was then filtered
through celite and the filtrate concentrated under
reduced pressure then freeze-dried from H2O af-
fording 4 (1.52 g, 98%). Rf = 0.50 (CH2Cl2/MeOH
7:3). 1H NMR (D2O): δ = 1.40–2.10 (m, 2H, H-6a
and H-6b), 3.20–3.85 (m, 6H, H-2, H-3, H-4, H-5, H-
7a, and H-7b), 4.70–4.75 (m, 1H, H-1ꢁ), 4.98–5.02
(m, 1H, H-1ꢂ). 13C NMR (D2O): δ = 33.5, 33.6 (C-
6ꢂ and C-6ꢁ), 58.8, 58.6 (C-7ꢂ and C-7ꢁ), 69.4–73.6
(C-2ꢂ, C-2ꢁ, C-3ꢂ, C-3ꢁ, C-4ꢂ, C-4ꢁ, C-5ꢂ, and C-
5ꢁ), 94.0, 94.3 (C-1ꢂ and C-1ꢁ). MS FAB > 0 (G/T):
m/z = 195 (M + H)+, 177 (M-OH)+. Anal for C7H14O6:
To a solution of 5 (220 mg, 0.52 mmol) in CH2Cl2
(15 ml) was added HBr (2.28 ml, 13 mmol, 5.7 M
in acetic acid). The reaction was stirred at r.t. for
16 h and then neutralized with saturated NaHCO3(aq)
(50 ml). The aqueous layer was extracted with
CH2Cl2 (3 × 70 ml), and the organic layers com-
bined, dried (Na2SO4), filtered, and evaporated un-
der reduced pressure. The crude product dissolved
in CH2Cl2 (15 ml) was added dropwise to a solu-
tion of 8-(cholest-5en-3ꢁ-yloxy)-3,6-dioxaoctan-1-ol
(287 mg, 0.57 mmol), silver trifluoromethanesul-
fonate (146 mg, 0.57 mmol) and sym-collidine (76 ꢀl,
0.57 mmol) in CH2Cl2 (5 ml). The reaction was stirred
at RT for 15 min before filtering through celite. The
filtrate was concentrated under reduced pressure,
Calcd:
7.32.
C 43.30, H 7.27; Found: C 43.13, H

A Convenient Synthetic Route to Mannose 6-Phosphonate–Cholesteryl Conjugate 245
and the residue purified by silica gel column
C46H75BrO11: Calcd: C 62.50, H 8.55; Found: C 62.77,
H 8.63.
chromatography (light petroleum/ether 4:1 → ether)
affording
6
(210 mg, 45%). Rf = 0.41 (light
1
petroleum/ether 1:4). H NMR (CDCl3): δ = 0.67 (s,
3H, H-18ꢁ), 0.86 (d, 6H, J = 6.6 Hz, H-26ꢁ), 0.91
(d, 3H, J = 6.4 Hz, H-21ꢁ), 0.99 (s, 3H, H-19ꢁ),
0.80–2.50 (m, 30H, H-Chol H-6a and H-6b), 1.71
(s, 3H, Orthoester-CH ), 2.07 (s, 3H, CH CO), 2.11
8-(Cholest-5-en-3β-yloxy)-3,6-dioxaoctan-1-yl-
6-Deoxy-6-dihydroxyphosphinylmethylene-α-D-
mannopyranoside Disodium Salt (M6Pn/TEGC)
A
solution of 7 (67 mg, 76 ꢀmol) in tris-
3
3
(s, 3H, CH CO), 3.10–3.30 (m, 1H, H-3ꢁ), 3.45–3.70
(trimethylsilyl)phosphite (5 ml) was refluxed (160◦C)
for 16 h. The reaction mixture was poured into
saturated NaHCO3(aq) (50 ml). The aqueous layer
was extracted with CH2Cl2 (3 × 50 ml), and the or-
ganic layers were combined, dried (Na2SO4), fil-
tered, and evaporated under reduced pressure. The
crude mixture (showing a single signal by 31P NMR
spectroscopy at 27 ppm) was dissolved in MeOH
(5 ml) and NaOMe (35 mg, 610 ꢀmol) was added.
After 24 h, the reaction was neutralized with 1 M
HCl and concentrated under reduced pressure. The
residue was purified by silica gel column chromatog-
raphy (i-PrOH/NH4OH/H2O 6:3:1), then treated with
ion exchange resin (DOWEX 50WX2, Na+ form)
affording M6Pn/TEGC (31 mg, 55%). Rf = 0.52 (i-
PrOH/NH4OH/H2O 6:3:1). 1H NMR (D2O): δ = 0.70–
2.30 (m, 47H, H-Chol, H-6a, H-6b, H-7a, and H-
7b), 3.20–4.00 (m, 17H, OCH CH O, H-2, H-3, H-4,
3
(m, 15H, OCH CH O, H-5, H-7a, and H-7b), 4.59
2
2
(dd, 1H, J = 2.6, 3.5 Hz, H-2), 5.00–5.20 (m, 2H,
H-3 and H-4), 5.30–5.38 (m, 1H, H-6ꢁ), 5.44 (d,
1H, H-1). 13C NMR (CDCl3): δ = 12.2 (C-18ꢁ), 15.6–
41.7 (C-Chol, Orthoester-CH3 and C-6), 21.1, 21.2
(CH3CO), 29.1 (C-7), 50.6, 56.5, 57.2 (C-9ꢁ, C-14ꢁ, and
C-17ꢁ), 62.4, 66.2 (OCH2CH2O), 67.7 (C-4), 69.0, 70.3
(OCH2CH2O), 70.9 (C-3), 71.0 (OCH2CH2O), 71.1 (C-
5), 71.3 (OCH2CH2O), 76.8 (C-2), 79.9 (C-3ꢁ), 97.9 (C-
1), 121.9 (Orthoester-Cquat), 141.4 (C-5ꢁ), 170.2, 170.7
(CH3CO).
8-(Cholest-5-en-3β-yloxy)-3,6-dioxaoctan-1-yl-
7-Bromo-6,7-dideoxy-2,3,4-tri-O-acetyl-α-D-
manno-heptopyranoside (7)
2
2
To a cooled (−5◦C) solution of 6 (160 mg, 0.18 mmol)
H-5, and H-3ꢁ), 5.30–5.40 (m, 1H, H-6ꢁ). 31P NMR
(D2O): δ = 23.0 (s, P(O)(ONa)2). MS FAB > O (G/T):
m/z = 803 (M + H)+, 781 (M-Na + 2H)+. MS FAB < 0
(G/T): m/z = 757 (M-2Na + H)−.
˚
and molecular sieves (3 A) in CH2Cl2 (5 ml) was
added trimethylsilyl trifluoromethanesulfonate (3.3
ꢀl, 18 ꢀmol). The reaction was stirred for 5 min then
neutralized with Et3N (50 ꢀl) before being diluted
with H2O (50 ml). The aqueous layer was extracted
with CH2Cl2 (3 × 50 ml), and the organic layers com-
bined, dried (Na2SO4), filtered, and evaporated un-
der reduced pressure. The resulting residue was pu-
rified by silica gel column chromatography (light
petroleum/ether 9:1 → ether) affording 7 (65 mg,
40%). Rf = 0.58 (light petroleum/ether 1:4). 1H NMR
(CDCl3): δ = 0.60 (s, 3H, H-18ꢁ), 0.79 (d, 3H, J =
6.6 Hz, H-26ꢁ), 0.80 (d, 3H, H-26ꢁ), 0.84 (d, 3H,
J = 6.5 Hz, H-21ꢁ), 0.92 (s, 3H, H-19ꢁ), 0.70–2.35
(m, 28H, H-Chol), 1.85–1.95 (m, 1H, H-6a), 1.91
(s, 3H, CH CO), 1.99 (s, 3H, CH CO), 2.07 (s, 3H,
REFERENCES
[1] (a) Sharon, N.; Lis, H. Sci Am 1993, 268, 82–88; (b)
Varki, A. Glycobiology 1993, 3, 97–130; (c) Lis, H.;
Sharon, N. Chem Rev 1998, 98, 637–674.
[2] (a) Tong, P. Y.; Gregoy, W.; Kornfeld, S. J Biol Chem
1989, 264, 7962–7969; (b) Tong, P. Y.; Kornfeld, S. J
Biol Chem 1989, 264, 7970–7975.
[3] (a) Dahms, N. M.; Lobel, P.; Kornfeld, S. J Biol Chem
1989, 264, 12115–12118; (b) Me´resse, S.; Bauer, U.;
Ludwig, T.; Mauxion, F.; Schmidt, A.; Hoflack, B. Med
Sci 1993, 9, 148–156.
[4] Barragan, V.; Menger, F. M.; Caran, K. L.; Vidil, C.;
More`re, A.; Montero, J.-L. Chem Commun 2001, 85–
86.
[5] Rabinowitz, R. J Org Chem 1963, 28, 2975–2978.
[6] Garbay-Jaureguiberry, C.; Ficheux, D.; Roques, B. P.
Int J Peptide Protein Res 1992, 39, 523–527.
[7] (a) Le Mare´chal, P.; Froussios, C.; Level, M.; Azerad,
R. Carbohydr Res 1981, 94, 1–10; (b) Wang, M.
F.; Crilley, M. M. L.; Golding, B. T.; McInally, T.;
Robinson, D. H.; Tinker, A. J Chem Soc Commun
1991, 667–668.
[8] For Several examples of one-carbon chain elonga-
tion of alcohols see: (a) Baer, H. H.; Hanna, H. R.
Carbohydr Res 1982, 102, 169–183; (b) Rouzaud, D.;
Sinay¨, P. J Chem Soc Chem Commun 1983, 1353–
1354; (c) Burford, C.; Cooke, F.; Roy, G.; Magnus, P.
3
3
CH CO), 2.00–2.10 (m, 1H, H-6b), 3.05–3.15 (m, 1H,
3
H-3ꢁ), 3.40–3.50 (m, 1H, H-7a), 3.50–3.70 (m, 13H,
OCH CH O and H-7b), 3.97 (td, 1H, J = 2.5, 9.9 Hz,
2
2
H-5), 4.75 (d, 1H, J = 1.5 Hz, H-1), 5.04 (t, 1H, H-
4), 5.21 (dd, 1H, J = 3.5 Hz, H-2), 5.25–5.30 (m, 1H,
H-6ꢁ), 5.27 (dd, 1H, H-3). 13C NMR (CDCl3): δ = 12.3
(C-18ꢁ), 19.1–42.7 (C-Chol), 21.1, 21.2, 21.5 (CH3CO),
29.2 (C-7), 34.9 (C-6), 50.6, 56.6, 57.2 (C-9ꢁ, C-14ꢁ,
and C-17ꢁ), 62.6, 67.7 (OCH2CH2O), 67.9 (C-5), 69.5
(C-3), 69.8 (C-4), 70.1 (C-2), 70.5, 71.0, 71.2, 71.3
(OCH2CH2O), 79.9 (C-3ꢁ), 97.8 (C-1), 121.9 (C-6ꢁ),
141.4 (C-5ꢁ), 170.2, 170.3, 170.5 (CH3CO). Anal for

246 Vidal, More`re, and Montero
Tetrahedron 1983, 39, 867–876; (d) Anderson,
R. Synthesis 1985, 717–734; (e) Jones, K.; Mood,
W. W. Carbohydr Res 1986, 155, 217–222; (f) Baer, H.
H.; Breton, L. R.; Shen, Y. Carbohydr Res 1990, 200,
377–398; (g) Goekjian, P. G.; Wu, T.-C.; Kang, H.-Y.;
Kishi, Y. J Org Chem 1991, 56, 6422–6434; (h) van
der Klein, P. A. M.; van Boom, J. H. Carbohydr Res
1992, 224, 193–200; (i) Baer, H. H.; Shen, Y.; Wu, X.
Carbohydr Res 1993, 241, 117–129; (j) De Raddt, A.;
Griengl, H.; Klempier, N. J Org Chem 1993, 58, 3179–
3184; (k) Aspinall, G. O.; McDonald, A. G.; Sood,
R. K. Can J Chem 1994, 72, 247–251; (l) Pakulski,
Z.; Zamojski, A. Polish J Chem 1994, 68, 1109–1114;
(m) El Garrouj, D.; Aliau, S.; Aumelas, A.; Borgna,
J.-L. J Med Chem 1995, 38, 2339–2348; (n) Pakulski,
Z.; Zamojski, A. Tetrahedron 1995, 51, 871–908;
(o) Barbud, C.; Bols, M.; Lundt, I.; Sierks, M. R.
Tetrahedron 1995, 51, 9063–9078; (p) Leeuwenburgh,
M. A.; Picasso, S.; Overkleeft, H. S.; van der Marel,
G. A.; Vogel, P.; van Boom, J. H. Eur J Org Chem
1999, 1185–1189; (q) Xin, Y.-C.; Zhang, Y.-M.; Mallet,
J.-M.; Glaudemans, C. P. J.; Sinay¨, P. Eur J Org Chem
1999, 471–476.
Synth Commun 1994, 24, 1519–1530; (c) Berkowitz,
D. B.; Bose, M.; Pfannenstiel, T. J.; Doukov, T. J Org
Chem 2000, 65, 4498–4508.
[11] Greene, T. W.; Wuts, P. G. Protective Groups in Or-
ganic Synthesis, 3rd ed.; Wiley: New York, 1999.
[12] Lay, L.; Manzoni, L.; Schmidt, R. R. Carbohydr Res
1998, 310, 157–171.
[13] Wang, P.; Shen, G.-J.; Wang, Y.-F.; Ichikawa, Y.; Wong,
C.-H. J Org Chem 1993, 58, 3985–3990.
[14] Bernet, B.; Vasella, A. Helv Chim Acta 1979, 62, 2400–
2410.
[15] For a review about glycosylation reactions see:
(a) Hanessian, S. In Preparative Carbohydrate
Chemisry; Hanessian, S. (Ed.); Marcel Dekker: New
York, 1997; (b) Collins, P.; Ferrier, R. Monosaccha-
rides: Their Chemistry and Their Roles in Natural
Products; Wiley: New York, 1995.
[16] Lafont, D.; Boullanger, P.; Chierici, S. New J Chem
1996, 20, 1093–1101.
[17] (a) Wang, W.; Kong, F. J Org Chem 1998, 63, 5744–
5745; (b) Wang, W.; Kong, F. Tetrahedron Lett 1998,
39, 1937–1940; (c) Crich, D.; Dai, Z.; Gastaldi, S. J Org
Chem 1999, 64, 5224–5229; (d) Wang, W.; Kong, F.
Tetrahedron Lett 1999, 40, 1361–1364; (e) Wang, W.;
Kong, F. J Org Chem 1999, 64, 5091–5095; (f) Wang,
W.; Kong, F. Angew Chem Int Ed Engl 1999, 38,
1247–1250.
[9] Dziewiszek, K.; Zamojski, A. Carbohydr Res 1986,
150, 163–171.
[10] (a) Seebach, D.; Corey, E. J. J Org Chem 1975, 40,
231–237; (b) Shen, Q.; Sloss, D. G.; Berkowitz, D. B.