Stereoselective synthesis of α-L-Fucp-(1,2)- and -(1,3)-β-D-Galp(1)-4-methylumbelliferone using glycosyl donor substituted by propane-1,3-diyl phosphate as leaving group

Article abstract of DOI:10.1039/b002754p

Stereoselective synthesis of α-L-Fucp-(1,2)- and -(1,3)-β-D-Galp(1)-4-methyllumbelliferone was accomplished using glycosyl donor substituted by propane-1,3-diyl phosphate as leaving group. The α-stereochemistry for the anomeric centre was assigned on the basis of the observed ¹³C-H coupling constant of 165.4 Hz for the bond. The results suggested that the bond-forming reaction intermediate was formed through participation of the second carbon acetoxy function or by an S_N2-like process.

Full text of DOI:10.1039/b002754p

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Stereoselective synthesis of ꢀ-L-Fucp-(1,2)- and -(1,3)-ꢁ-D-Galp(1)-
4-methylumbelliferone using glycosyl donor substituted by propane-
1,3-diyl phosphate as leaving group
1
Hariprasad Vankayalapati and Gurdial Singh*
Department of Chemistry, University of Sunderland, Sunderland, UK SR1 3SD.
E-mail: gurdial.singh@sunderland.ac.uk
Received (in Cambridge, UK) 6th April 2000, Accepted 2nd June 2000
Published on the Web 27th June 2000
The synthesis of the disaccharides α--Fucp-(1,2)- and α--Fucp-(1,3)-β-D-Galp(1)-4-methylumbelliferone as
fucosidase substrates was accomplished by activation of the anomeric centre of 2,3,4-tri-O-acetyl- and 2,3,4,6-tetra-
O-acetyl-α,β--fuco- and --galactopyranosyl propane-1,3-diyl phosphates with TMSOTf and with minimal
protection of 4-methylumbelliferyl β--galactopyranoside.
Introduction
The importance of the role that carbohydrates play in the main-
tenance of health and the onset of disease has received due
recognition during the last two decades. The diversity of these
carbohydrate structures can be found in oligosaccharides that
are covalently attached to lipids and proteins both at cell sur-
faces and in biological fluids. The length of these oligosacchar-
ides is normally less than twenty sugar residues, yet the possible
changes in configuration, oxidation and/or reduction states,
and points of attachment give them a wide range of biological
functions. Research in organic chemistry and molecular biology
has been stimulated by the desire to attain an understanding
of how and why these structures are recognised by enzymes,
antibodies and lectins.
The fucose-containing disaccharides, e.g. -Fuc-α-1,3-β--
Galp and -Fuc-α-1,2-β-D-Galp, are usually found at the
non-reducing terminus of oligosaccharides of the blood-group-
specific glycoproteins and glycolipid1 with the structures
-Fuc-α-1,2-Gal-β-1,4-GlcNAc-β- and the grouping -Fuc-α-
1,3-Gal-β-1,4-Glu both occurring among human milk
oligosaccharides.2 Furthermore in sialyl Lewis X the α--
Scheme 1 Reagents and conditions: i, Ac2O, Py, RT, 12 h; ii, 33% HBr–
fucopyranosyl group plays a pivotal role in binding to E-,
L- and P-selectins.3 As part of our ongoing programme of syn-
thesis of oligosaccharides that occur in human milk and of
their analogues as fucosidase substrates, we describe the syn-
thesis of both α--Fuc-1,3-β-galactopyranoses, α--Fuc-1,2-β-
galactopyranoses and also the corresponding disaccharides
having a 4-methylumbelliferyl moiety attached at the anomeric
centre of -galactopyranose.
AcOH, RT, 15 min; iii, Ag2CO3, acetone, 0.5 h.
ose 4 in 90% overall yield.7 Treatment of 4 with propane-1,3-
diyldioxyphosphoryl chloride 54d afforded the phosphates 6
and 7, as an inseparable crystalline mixture, in 65% yield,
1
in the ratio 9:1 as determined by H NMR. For the major
isomer 6 a resonance at δ 5.92 was observed as a doublet of
doublets (dd) for the anomeric proton and exhibited couplings
of 3.3 and 2.6 Hz, whilst for the isomer 7 this resonance
occurred at δ 5.35 with couplings of 5.9 and 7.9 Hz. The 13C
NMR data were most informative for assignment of the stereo-
chemistry at C-1 of 6 and 7; in the case for the former the
resonance was observed at δC 94.63 with a JC-P of 4.9 Hz whilst
for the latter anomer this was found at δC 96.71 with JC-P of
4.4 Hz.
1,3,4,6-Tetra-O-acetyl-α--galactopyranose 8 was prepared
as reported by Chittenden8 in a yield of 70%. Having both
saccharides available we investigated the coupling of the phos-
phate 6 and 7 with 8, Scheme 2, and were gratified that this
proceeded uneventfully when we employed trimethylsilyl triflate
(TMSOTf) as the activating agent, and gave the peracetylated
derivative of disaccharide α--Fucp-(1,2)-α--Galp, compound
9, in 63% yield after chromatographic purification on silica gel.
The α-stereochemistry for the anomeric centre was assigned on
Results and discussion
We chose to employ propane-1,3-diyl phosphate as the ano-
meric activating group for the synthesis of these compounds
as we had successfully used it to obtain β-O-glycosides.4 In
addition we reasoned that the displacement of this function
with 4-methylumbelliferone would provide access to glycosides
that are used as convenient substrates for the fluorimetric assay
of glycoside hydrolyase activity5 and as ligands in carbohydrate–
protein interaction studies.6
Acetylation of -fucopyranose 1 with acetic anhydride and
pyridine, Scheme 1, afforded 1,2,3,4-tetra-O-acetyl-α,β--fuco-
pyranose 2, which was converted to the α--fucopyranosyl
bromide 3. Oxidation of the latter with silver carbonate in
acetone gave the required 2,3,4-tri-O-acetyl-α,β--fucopyran-
DOI: 10.1039/b002754p
J. Chem. Soc., Perkin Trans. 1, 2000, 2187–2193
This journal is © The Royal Society of Chemistry 2000
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Scheme 2 Reagents and conditions: i, 1.5 equiv. TMSOTf, CH2Cl2, Ϫ78 ЊC; ii, NH3(g), MeCN, 0 ЊC; iii, 5, N-MeIm, 16 h; iv, NaOMe, MeOH, RT,
30 min.
the basis of the observed 13C–1H coupling constant of 165.4 Hz
for the newly formed bond.9 To further establish that the coup-
ling reaction had proceeded with the desired stereochemical
outcome we undertook the removal of the acetate protecting
groups in 9 with NaOMe in methanol and obtained the corre-
sponding disaccharide which displayed spectral and physical
properties that were in agreement with those reported by
Lemieux.10 However, if the coupling of 6 and 7 with 8 was
conducted with a catalytic amount of TMSOTf, the formation
of the β-isomer of 9 was observed in 46% yield along with
recovered starting material (39%). In this case a coupling of
159.6 Hz was observed for the 1,2-linkage. These observations
suggest that the disaccharide 9 is the thermodynamic product
and is the result of the bond-forming reaction proceeding via
an oxonium ion intermediate whilst the corresponding β-isomer
is formed via participation of the C-2 acetoxy function or by an
SN2-like process.
basis of the 13C–1H coupling constant which was determined as
159.2 Hz.
Having had success in the introduction of the 4-methyl-
umbelliferone function we decided to investigate its introduc-
tion at the anomeric centre of galactose at an early stage and to
study the subsequent coupling reaction with the fucopyranosyl
phosphates 6 and 7, Scheme 3. Hence, selective removal of the
anomeric acetate group of 148b afforded 2,3,4,6-tetra-O-acetyl-
α,β--galactopyranose 15 in 96% yield. Treatment of 15 with
propane-1,3-diyldioxyphosphoryl chloride
5 afforded the
phosphates 16 as a mixture of separable crystalline α (mp 143–
145 ЊC) and β isomers in the ratio of 20:1, respectively, in a
combined yield of 63%. The displacement of the phosphate 16ꢀ
was accomplished with 4-methylumbelliferone and gave 4-
methylumbelliferyl† 2,3,4,6-tetra-O-acetyl-β--galactopyrano-
side 17 in 68% yield; the same outcome was observed if the
mixture of 16ꢀ,ꢁ was used. The stereochemistry of the ano-
meric linkage was assigned on the basis of a 13C–1H coupling
constant of 160.2 Hz. Subsequent deacetylation of the galac-
tose derivative 17 with sodium methoxide in methanol cleanly
afforded the saccharide 18 in 83% yield. The primary hydroxy
group of the latter was protected as the silyl ether on treatment
with tert-butyldiphenylsilyl chloride (TBDPSCl) and afforded
the partially protected 4-methylumbelliferyl β--galactopyran-
oside 19 in 79% yield after chromatographic purification. At
this juncture we investigated the chemistry of 19 with the
fucopyranosyl phosphates 6 and 7, employing one mole equiv-
alent of TMSOTf as the activator. This treatment resulted in
the formation of the disaccharide 20 in 52% isolated yield along
with a trace amount of the corresponding 1,2-linked disacchar-
ide (23; see below) as evidenced by TLC; all of our attempts to
isolate the 1,2-linked product by chromatography proved
unfruitful. That the coupling reaction had proceeded regio-
specifically at the C-3 OH function was tentatively assigned on
The anomeric acetate group of 9 was selectively removed
by employing ammonia gas in acetonitrile11 and gave the
disaccharide 10 in 69% yield after chromatographic purifi-
cation. Treatment of 10 with propane-1,3-diyldioxyphosphoryl
chloride 5 afforded the mixture of anomeric phosphates 11 in
1
60% yield, in the ratio 20:1 (11ꢀ major) as determined by H
NMR. In the 31P NMR spectrum the resonance for 11ꢀ
occurred at δP Ϫ10.5 whilst that for 11ꢁ was found at δP Ϫ11.5.
At this juncture we embarked upon a study of the displacement
reaction of the mixture of phosphates 11 with 4-methylum-
belliferone, as this function has been used extensively in the
fluorimetric assay of glycosides. The propane-1,3-diyl phos-
phate group was successfully displaced by 4-methylumbelli-
ferone using 0.2 mol equiv. of TMSOTf as the activator and
afforded the β-linked disaccharide 12 in 56% yield following
chromatography. This result is an improvement on the reported
methods for the introduction of the 4-methylumbelliferone
group which normally proceed in yields in the order of 14%.
Removal of the acetate function of 12 yielded the fully
deprotected disaccharide 13, Scheme 2. The stereochemical
integrity of the anomeric centre of 13 was established on the
1
the basis of H and 13C NMR data. Removal of the primary
silyl ether group afforded 21, which on treatment gave the fully
† ‘4-Methylumbelliferyl’ refers to 4-methylcoumarin-7-yl.
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Scheme 3 Reagents and conditions: i, NH3(gas), MeCN, 0 ЊC; ii, N-MeIm, CH2Cl2, 0 ЊC, 16 h; iii, TMSOTf, 0.2 equiv., Ϫ78 ЊC, 0.5 h; iv, NaOMe,
MeOH, RT, 0.5 h; v, TBDPSCl, Im, DMF, RT, 8 h; vi, TMSOTf, 1 equiv., Ϫ78 ЊC, 1 h; vii, Bu4NF, THF; viii, NaOMe, MeOH.
deprotected α--Fucp-1,3-β--Gal(1)-4-methylumbelliferone 22
in 59% yield for the two steps, Scheme 3. That the newly formed
bond had a 1,3-linkage was strongly supported by the fact that
the spectral and physical properties of 22 were different from
those of the 1,2-linked isomer 13 that we had prepared earlier.
In order to further support these conclusions we undertook the
synthesis of both 13 and 22 by employing classical coupling
chemistry, Scheme 4. Thus coupling of 2,3,4-tri-O-acetyl-α--
fucopyranosyl bromide 3 with the partially protected derivative
19 using tetraethylammonium bromide afforded the disacchar-
ides 20 and 23 in yields of 27% and 51%, respectively. Removal
of the silyl and acetate functions resulted in the formation of
the isomeric fully deprotected disaccharides 22 and 13 which
had spectral and physical properties in agreement with the
compounds prepared using the propane-1,3-diyl phosphate
coupling protocol, Schemes 2 and 3.
as follows: chemical shifts δ (ppm), [number of protons,
multiplicity, coupling constants J (Hz), and assignment].
Residual protic solvent CHCl3 (δH 7.26) was used as the internal
reference. 13C NMR spectra were recorded in CDCl3, at 67.8
MHz on the JEOL GSX 270 NMR spectrometer, using the
central resonance of CDCl3 (δC 77.0) as the internal reference.
13P NMR spectra were recorded in CDCl3, at 109.25 MHz on
a JEOL GSX 270 NMR spectrometer, using trimethyl phos-
phate as the external reference. IR spectra were recorded on
a UNICAM series FTIR spectrometer. Mass spectra were
obtained on an AEI MS 902 or a VG ZAB-E spectrometer. UV-
visible spectra were measured on a UNICAM UV/VIS spectro-
photometer. Microanalysis were performed by MEDAC Ltd,
Surrey. Mps were determined on a GallenKamp capillary
melting-point apparatus and are uncorrected. Optical rotations
were measured in CHCl3 solution using a Bellingham & Stanley
ADP 220 polarimeter. [α]D-Values are in units of 10Ϫ1 deg cm2
Conclusions
g
Ϫ1. Flash chromatography was carried out using Fluka silica
gel 60 (230–400 mesh) unless otherwise indicated. Analytical
TLC was performed using precoated aluminium plates (Merck
Kiselgel 60 F254) and visualised by UV, phosphomolybdic acid
or basic aq. potassium permanganate solutions. ‘Petrol’ refers
to petroleum spirit (distillation range 40–60 ЊC) which was
distilled prior to use, and ether refers to diethyl ether.
In summary we have established that fucose-containing
disaccharides can be prepared using propane-1,3-diyl phos-
phate activation of the anomeric centre of glycosides in a regio/
stereoselective manner.
All reactions were carried out under an argon or nitrogen
atmosphere in oven-dried glassware unless otherwise stated.
CH2Cl2 and DMF were distilled from calcium hydride and
stored over 4 Å molecular sieves. Aqueous solutions are
saturated unless otherwise specified.
Experimental
General methods
1H NMR spectra were recorded in CDCl3 (unless stated other-
wise) on a JEOL GSX 270 NMR spectrometer and are reported
J. Chem. Soc., Perkin Trans. 1, 2000, 2187–2193
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Scheme 4 Reagents and conditions: ii, Bu4NF, THF; iii, NaOMe, MeOH, RT, 0.5 h.
1,2,3,4-Tetra-O-acetyl-ꢀ,ꢁ-L-fucopyranose 27
graphy (1:1 EtOAc–petrol) and afforded 2,3,4-tri-O-acetyl-α,β-
-fucopyranose 4 (7.35 g, 94%).
A solution of -fucose 1 (5 g, 30.45 mmol) in dry pyridine (50
ml) containing acetic anhydride (35 ml) was stored at 4 ЊC for
12 h. Following this water (10 ml) was added and, after 1 h, the
solution was extracted with CH2Cl2 (100 ml). The combined
CH2Cl2 layers were back-extracted with 100 ml of cold 1 M
H2SO4 and then with cold aq. NaHCO3 (100 ml), and finally
washed with water (100 ml). The organic phase was dried
(Na2SO4) and concentrated to give α,β--fucopyranosyl tetra-
acetate 2 as a thick syrup (11.00 g, 100%).
For isomer 4ꢀ, IR (film) νmax 3357, 1745, 1369 cmϪ1; δH 1.24
(3H, d, J 6.6), 2.00 (3H, s), 2.10 (3H, s), 2.17 (3H, s), 4.39 (1H,
appt d, J 6.6), 5.12 (1H, dd, J 4.0, 3.3), 5.31 (1H, dd, J 4.0, 1.3),
5.43 (1H, dd, J 4.0, 3.3), 5.46 (1H, d, J1,2 3.3, H-1); δC 15.86,
20.55, 20.60, 20.75, 64.33, 67.72, 68.45, 71.26, 90.57 (C-1),
170.13, 170.43, 170.66.
For isomer 4ꢁ, δH 1.14 (3H, d, J 6.6), 2.05 (3H, s), 2.10 (3H,
s), 2.18 (3H, s), 3.83 (1H, appt d, J 6.6), 4.64 (1H, d, J1,2 7.9,
H-1), 5.01 (1H, dd, J 5.3, 2.6), 5.25 (1H, d, J 1.3), 5.39 (1H, d,
J 4.0); δC 14.09, 20.50, 20.53, 20.93, 60.38, 69.42, 70.26, 70.78,
95.75 (C-1), 170.10, 170.47, 170.57.
For isomer 2ꢀ, IR (film) νmax 1751, 1371 cmϪ1; δH 1.29 (3H, d,
J 6.6), 2.00 (3H, s), 2.05 (3H, s), 2.10 (3H, s), 2.18 (3H, s), 4.08
(1H, appt d, J 7.3), 4.39 (1H, appt d, J 6.6), 5.10–5.16 (1H, m),
5.39 (1H, d, J 3.3), 6.29 (1H, d, J1,2 4.6, H-1); δC 15.97, 20.44,
20.56, 20.60, 20.64, 67.65, 69.04, 70.19, 83.22, 90.29 (C-1),
169.88, 170.12 (2C), 170.47.
2Ј,3Ј,4Ј-Tri-O-acetyl-ꢀ,ꢁ-L-fucopyranosyloxy-1,3,2-dioxa-
phosphinane 2-oxide 6 and 7
For isomer 2ꢁ, δH 1.13 (3H, d, J 6.6), 2.09 (3H, s), 2.12 (3H,
s), 2.13 (3H, s), 2.19 (3H, s), 3.86–3.92 (1H, m), 4.20–4.34 (1H,
m), 5.01–5.07 (1H, m), 5.30 (1H, dd, J 3.3, 1.3), 5.43 (1H, d, J1,2
7.3, H-1); δC 15.91, 20.41, 20.49, 20.57, 20.90, 64.02, 68.39,
70.84, 82.07, 95.45 (C-1), 170.01, 170.32, 170.65, 170.82.
2,3,4-Tri-O-acetyl-α,β-L-fucopyranose 4 (5.00 g, 17.2 mmol)
was dissolved in CH2Cl2 (50 ml) and the solution was cooled to
0 ЊC. To this solution were added 2-chloro-1,3,2-dioxaphosphin-
ane 2-oxide (5.4 g, 34.39 mmol) and 1-methylimidazole (2.8 g,
34.48 mmol) dropwise over a period of 15 min. Stirring was
continued for 16 h, with gradual warming to room temperature.
The solvent was removed, the residue was re-dissolved in
CH2Cl2 (50 ml), and the solution was evaporated to remove
traces of 1-methylimidazole. Addition of CH2Cl2 (50 ml) to the
residue gave a pale yellow solution, which was washed succes-
sively with ice–water (50 ml), aq. NaHCO3 (2 × 50 ml) and
water (50 ml). The organic layer was dried over Na2SO4 and
the solvent was removed in vacuo. The oily residue was purified
by column chromatography (EtOAc–petrol 1:1) to afford the
phosphates 6 and 7 (ratio 9:1) as an inseparable crystalline
mixture (4.68 g, 65%), mpmix 151–153 ЊC; [α]D22 Ϫ100.6 (c 3.2,
CHCl3).
2,3,4-Tri-O-acetyl-ꢀ-L-fucopyranosyl bromide 37
The mixture of α,β-fucopyranosyl tetraacetates 2 (10 g, 30.1
mmol) was dissolved in glacial acetic acid (20 ml) and 30 ml of
33% HBr–HOAc was added slowly at 20 ЊC. Stirring was
continued for 15 min and the yellow coloured solution was
dissolved in CH2Cl2 (200 ml), and back-extracted with cold
water (2 × 200 ml), cold 1 M aq. NaHCO3 (200 ml) and finally
with 200 ml of water. The CH2Cl2 layer was dried over Na2SO4
and concentrated in vacuo to give the α--fucopyranosyl
bromide 3 as a thick syrup (10.32 g, 97%), δH 1.21 (3H, d, J 7.3),
2.05 (3H, s), 2.11 (3H, s), 2.18 (3H, s), 4.08 (1H, appt d, J 7.3),
4.37 (1H, appt d, J 6.6), 5.00 (1H, appt d, J 4.0), 5.36 (1H, dd,
J 3.3, 2.6), 6.68 (1H, d, J1,2 4.0, H-1); δC 15.50, 20.49, 20.56,
20.72, 67.84, 68.40, 69.79, 69.98, 89.27, 169.79, 170.12, 170.25.
For isomer 6, IR (KBr) νmax 1745, 1373, 1216 cmϪ1; δH 1.24
(3H, d, J 6.6, CH3), 1.85–1.89 (1H, m, JP-H 15.17, Hax-5), 2.02
(3H, s), 2.10 (3H, s), 2.19 (3H, s), 2.30–2.36 (1H, m, JP-H 15.2,
Heq-5), 3.90 (1H, dq, J 7.3, 6.6), 4.33–4.59 (4H, m), 5.01 (1H,
appt d, J 3.3, 3.3), 5.22 (1H, dd, J 3.3, 2.6), 5.31–5.33 (1H, m),
5.92 (1H, dd, J1,2 3.3, 2.6, H-1); δC 15.82, 20.52, 20.60 (2C),
25.63, 66.92, 67.35, 68.80, 68.86 (2C), 69.75, 70.36, 94.63 (d,
JC-P 4.93, C-1), 170.14 (2C), 170.46; δP Ϫ10.36.
For isomer 7 δH 1.19 (3H, d, J 6.6), 1.78–1.83 (1H, m, JP-H
15.2, Hax-5), 2.02 (3H, s), 2.10 (3H, s), 2.19 (3H, s), 2.23–2.28
(1H, m, JP-H 15.2, Heq-5), 3.67 (1H, dq, J 6.0, 5.9), 4.07–4.31
(2H, m), 4.33–4.59 (4H, m), 5.31–5.33 (1H, m), 5.35 (1H, dd,
2,3,4-Tri-O-acetyl-ꢀ,ꢁ-L-fucopyranose 47
The α--fucopyranosyl bromide 3 (9.5 g, 26.9 mmol) was dis-
solved in acetone (50 ml) containing 1.4 ml of water at 0 ЊC. To
the resulting solution was added Ag2CO3 (7.4 g, 26.9 mmol)
and the mixture was stirred for 0.5 h. The reaction mixture was
filtered through a pad of Celite and the filtrate was evaporated
to give a thick syrup, which was purified by column chromato-
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J1,2 5.9, 7.9, H-1); δC 15.85, 20.49, 20.65, 20.74, 25.79, 66.83,
68.91, 68.97, 69.31, 70.27, 70.74, 96.71 (d, JC-P 4.41, C-1),
170.41, 170.43, 170.49; δP Ϫ10.80; m/z (CI, NH3) (Found: Mϩ,
410.0978. C15H23O11P requires M, 410.0978) (Found: C, 43.68;
H, 5.58; P, 7.58. C15H23O11P requires C, 43.91; H, 5.65; P,
7.55%).
2-[3Ј,4Ј,6Ј-Tri-O-acetyl-2Ј-O-(2Љ,3Љ,4Љ-tri-O-acetyl-ꢀ-L-fuco-
pyranosyl)-ꢀ,ꢁ-D-galactopyranosyloxy]-,1,3,2-dioxaphosphinane
2-oxide 11ꢀ and 11ꢁ
The title compounds were prepared using a similar procedure to
that employed for compounds 6 and 7, by treating compound
10 (1.2 g, 2.1 mmol) with propane-1,3-diyldioxyphosphoryl
chloride 5 (0.64 g, 4.0 mmol) in CH2Cl2 (15 ml) and 1-
methylimidazole (0.34 g, 4.15 mmol) at RT for 16 h. Chromato-
graphic purification of the resulting residue (EtOAc–‘petrol’
1:1) gave an inseparable crystalline mixture of 11ꢀ and 11ꢁ
(ratio 9:1) (861 mg, 60%), mp 109–112 ЊC; [α]D20 ϩ36.23 (c 2.8,
CHCl3).
1,3,4,6-Tetra-O-acetyl-ꢀ-D-galactopyranose 8
The title compound was prepared as detailed by Chittenden.8
Thus β--galactose pentaacetate (5 g, 12.8 mmol) in TFA (17.5
ml) containing water (1.75 ml) was stirred at RT for 5 h and
concentrated in vacuo. The residue was dissolved in toluene (20
ml), which was subsequently removed in vacuo. The residual
product was crystallised from Pri2O to give 8 (6.23 g, 70%), mp
149–151 ЊC; [α]D20 ϩ125.3 (c 1.4, CHCl3); IR (film) νmax 3444,
1747, 1373 cmϪ1; δH 2.04 (3H, s), 2.06 (3H, s), 2.15 (3H, s), 2.18
(3H, s), 4.07–4.09 (2H, m), 4.14 (1H, dd, J 10.6, 4.0), 4.26 (1H,
t, J 6.6), 5.15 (1H, appt d, J 3.3), 5.44 (1H, dd, J 3.3, 1.3), 6.29
(1H, d, J1,2 4.0, H-1); δC 20.49, 20.55, 20.67, 20.86, 61.23, 65.87,
67.48, 68.60, 70.27, 91.87 (C-1), 169.49, 170.08, 170.44, 170.88.
For isomer 11ꢀ, IR (KBr) νmax 1749, 1214 cmϪ1; δH 1.23 (3H,
d, J 7.3), 1.78–1.84 (1H, m, JP-H 15.2, Hax-5), 2.24–2.30 (1H, m,
JP-H 15.2, Heq-5), 1.97 (3H, s), 2.04 (3H, s), 2.05 (6H, s), 2.08
(3H, s), 2.17 (3H, s), 3.80 (1H, appt d, J 8.6), 3.92–4.04 (2H, m),
4.07 (1H, dd, J 7.3, 3.3), 4.15 (1H, t, J 5.3), 4.43–4.54 (4H, m),
4.62 (1H, d, J 7.9), 4.96 (1H, dd, J 9.2, 2.0), 5.07 (1H, d, J 7.3),
5.21–5.38 (2H, m), 5.43 (1H, d, J1Љ,2Љ 2.6, H-1Љ), 5.90 (1H, dd,
J1Ј,2Ј 3.3, H-1Ј); δC 16.00 (CH3), 20.33, 20.38, 20.42, 20.51, 20.60,
20.79, 25.62, 61.67, 66.64, 67.39, 67.65, 68.65, 68.45 (d, J 4.67),
68.79, 68.94, 69.26, 69.97, 71.58, 95.14 (d, J 5.46, C-1Ј), 95.39
(d, J 6.23, C-1Љ), 169.15, 169.68, 169.87, 169.98, 170.21, 171.41;
δP Ϫ10.54.
1Ј,3Ј,4Ј,6Ј-Tetra-O-acetyl-2Ј-O-(2,3,4-tri-O-acetyl-ꢀ-L-fuco-
pyranosyl)-ꢀ-D-galactopyranose 9
Propane-1,3-diyl 2,3,4-tri-O-acetyl-α,β-L-fucopyranosyl phos-
phate 6/7 (2.0 g, 4.9 mmol) was dissolved in dry CH2Cl2 (20 ml)
and the solution was cooled to Ϫ78 ЊC. To the resultant solu-
tion was added TMSOTf (1.62 g, 7.3 mmol) and, after 5 min
stirring, a solution of glycosyl acceptor 8 (1.69 g, 4.85 mmol) in
CH2Cl2 (5 ml) was added. The reaction mixture was stirred at
Ϫ78 ЊC for 30 min and was then allowed to warm up to 0 ЊC.
The reaction mixture was quenched with aq. NaHCO3 (20 ml)
and extracted into CH2Cl2 (20 ml). The organic layer was dried
over anhydrous Na2CO3, concentrated, and the residue was
purified by column chromatography (EtOAc–‘petrol’ 1:1) to
give compound 9 (1.93 g, 63%), mp 113–117 ЊC; [α]D22 ϩ32.85
(c 2.8, CHCl3); IR (film) νmax 1751, 1373 cmϪ1; δH 1.19 (3H, d,
J 6.6), 1.97 (3H, s), 2.00 (3H, s), 2.02 (3H, s), 2.03 (3H, s), 2.04
(3H, s), 2.14 (3H, s), 2.17 (3H, s), 3.78 (1H, dd, J 6.6, 5.9), 4.06–
4.16 (3H, m), 4.25 (1H, t, J 6.6), 4.49 (1H, d, J 7.9), 4.94 (1H, dd,
J 9.9, 3.3), 5.07 (1H, dd, J 10.6, 7.9), 5.20 (1H, d, J 2.6), 5.28
(1H, dd, J 9.2, 3.3), 5.47 (1H, d, J1,2 2.6, H-1), 6.26 (1H, d, J1Ј,2Ј
4.0, H-1); δC 16.12 (CH3), 20.49, 20.57 (3C), 20.65 (2C), 20.70,
61.09, 67.73, 68.09, 68.38, 68.69, 69.22, 69.90, 71.34, 73.76,
89.77 (C-1Ј), 101.67 (C-1), 169.22, 169.33, 169.84, 169.94,
170.12, 170.35, 170.58; m/z (CI, NH3) [Found: (M ϩ NH4),
638.2294. C26H40NO17 requires m/z, 638.2296].
For isomer 11ꢁ, (selected features) δH 1.20 (3H, d, J 6.6), 5.82
(1H, dd, J1Ј,2Ј 6.6, H-1Ј); δC 97.88 (d, J 5.71, C-1Љ); δP Ϫ11.50;
m/z (CI, NH3) [Found: (M ϩ NH4), 716.1266. C27H43NO19P
requires m/z, 716.1267] (Found: C, 46.46; H, 5.52; P, 4.65.
C27H39O19P requires C, 46.42; H, 5.58; P, 4.44%).
4-Methylumbelliferyl 3Ј,4Ј,6Ј-tri-O-acetyl-2Ј-(2Љ,3Љ,4Љ-tri-O-
acetyl-ꢀ-L-fucopyranosyl)-ꢁ-D-galactopyranoside 12
The title compound was prepared using a similar method to
that employed for 9, by activating phosphates 11ꢀꢁ (1 g, 1.4
mmol) with TMSOTf (0.08 g, 0.35 mmol) at Ϫ78 ЊC in CH2Cl2
(10 ml). Following the addition of 4-methylumbelliferone (0.25
g, 1.43 mmol) at the same temperature the reaction mixture
was stirred for 0.5 h and allowed to warm to 0 ЊC. The solution
was quenched with aq. NaHCO3 (10 ml) and the solvent was
removed in vacuo. The resultant residue was dissolved in
CH2Cl2 (10 ml), and the extract was dried over Na2CO3, con-
centrated, and purified by column chromatography (EtOAc–
‘petrol’ 1:1) to afford 12 as a white solid (560 mg, 56%), mp
121–123 ЊC; [α]D18 ϩ37.2 (c 0.8, CHCl3); IR (KBr) νmax 1745,
1614, 1371 cmϪ1; δH 1.15 (3H, d, J 6.6), 1.96 (3H, s), 1.98 (3H,
s), 2.03 (3H, s), 2.05 (3H, s), 2.07 (3H, s), 2.13 (3H, s), 2.43 (3H,
s, CH3), 3.93 (1H, dd, J 7.3, 6.6), 4.07–4.16 (3H, m), 4.24 (1H,
dd, J 5.3, 4.6), 4.56 (1H, appt d, J 7.9), 4.95 (1H, dd, J 6.6, 4.0),
5.15 (1H, d, J1Љ,2Љ 7.9, H-1Љ), 5.19 (1H, dd, J 7.3, 4.0), 5.34 (1H,
d, J 3.3), 5.47–5.52 (1H, m), 5.67 (1H, dd, J1Ј,2Ј 4.0, 3.3, H-1Ј),
6.20 (1H, s), 7.02 (1H, dd, J 7.9, 2.0), 7.12 (1H, d, J 4.0),
7.53 (1H, d, J 9.2); δC 16.00 (CH3), 18.59 (CH3), 20.47, 20.47,
20.50, 20.57, 20.60, 20.62, 20.96, 61.25, 67.58, 67.86, 68.44,
69.46, 69.91, 71.20, 72.95, 83.26, 96.04 (C-1Ј), 103.85 (C-1Љ),
104.24, 113.04, 114.14, 115.20, 125.74, 152.18, 154.84, 159.12,
168.83, 169.86, 170.04, 170.08, 170.28, 170.52, 170.54; m/z (CI,
NH3) [Found: (M ϩ NH4), 754.2560. C34H44NO18 requires
m/z, 754.2558].
3,4,6-Tri-O-acetyl-2-O-(2,3,4-tri-O-acetyl-ꢀ-L-fucopyranosyl)-
ꢀ,ꢁ-D-galactopyranose 10
To solution of ammonia in CH3CN (25 ml), prepared by bub-
bling ammonia gas through the solvent at 0 ЊC (10 min), was
added compound 9 (1.5 g, 2.4 mmol) and the mixture was
stirred at RT for 24 h. The solvent was then removed in vacuo
and the residue was purified by column chromatography
(EtOAc–‘petrol’ 1:1) to give a mixture of 10ꢀ and 10ꢁ anomers
in the ratio 3:1 (960 mg, 69%), mp 74–78 ЊC; [α]D19 ϩ24.6 (c 2.4,
CHCl3).
For isomer 10ꢀ IR (KBr) νmax 3352, 1753 cmϪ1; δH 1.24 (3H, t,
J 7.3), 1.99 (3H, s), 2.01 (3H, s), 2.03 (3H, s), 2.05 (3H, s), 2.07
(3H, s), 2.18 (3H, s), 3.69 (1H, dd, J 7.9, 2.0), 3.79 (1H, t, J 7.9),
3.88 (1H, m), 3.98–4.20 (2H, m), 4.66 (1H, d, J 7.9), 4.72 (1H, dd,
J 7.9, 4.6), 5.00 (1H, dd, J 7.3, 3.3), 5.08–5.18 (2H, m), 5.21
(1H, d, J1Ј,2Ј 3.3), 5.30–5.37 (1H, m), 5.39 (1H, d, J1,2 3.3); δC
16.02 (CH3), 20.51, 20.57 (2C), 20.66, 20.70, 20.94, 60.34, 61.46,
67.38, 68.14, 69.05, 69.45, 70.00, 71.03, 71.46, 91.53 (C-1Ј),
96.22 (C-1), 169.70, 169.81, 170.09, 170.14, 170.61, 170.52.
For isomer 10ꢁ, (selected features) δH 1.18 (3H, t, J 5.94,
CH3), 4.44 (1H, d, J1,2 6.6, H-1); δC 101.86 (C-1).
4-Methylumbelliferyl 2Ј-O-(ꢀ-L-fucopyranosyl)-ꢁ-D-galacto-
pyranoside 13
To a solution of the disaccharide 12 (500 mg, 0.68 mmol) in
methanol (50 ml) was added NaOMe (0.055 g, 1 mmol) and the
resultant solution was stirred at RT for 0.5 h. The solution was
neutralised by passage down a Dowex 50 (Hϩ) ion-exchange
resin. Evaporation of the combined fractions gave the title
compound as a white solid (205 mg, 62%), mp 251–253 ЊC; [α]D22
ϩ24.7 (c 0.7, H2O); IR (KBr) νmax 3480, 1709, 1615, 834 cmϪ1
;
J. Chem. Soc., Perkin Trans. 1, 2000, 2187–2193
2191

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λmax (H2O) 318, 294, 252 nm; δH (DMSO-d6) 1.09 (3H, d, J 6.6),
2.39 (3H, s), 3.46–3.69 (3H, m), 3.53 (1H, appt d, J 6.0), 3.76
(1H, dd, J 10.0, 7.3), 3.86 (1H, br d, J 4.0), 3.92 (1H, br d,
J 2.7), 4.06 (1H, dd, J 9.6, 3.3), 4.24 (1H, q, J 7.3), 4.34 (1H, dd,
J 5.3, 3.3), 5.09 (1H, appt d, J1Љ,2Љ 8.0, H-1Љ), 5.70 (1H, d, J1Ј,2Ј
3.30, H-1Ј), 6.23 (1H, s), 7.03 (1H, dd, J 7.3, 2.0), 7.09 (1H, d,
J 2.7), 7.67 (1H, d, J 9.3); δC (DMSO-d6) 16.52, 18.10, 60.21,
67.82, 68.18, 69.06, 70.62, 71.00, 72.53, 73.12, 73.21, 96.91 (JCH
173.5, C-1Љ), 101.99 (JCH 159.2, C-1Ј), 104.16, 111.73, 114.15,
114.21, 126.36, 153.33, 154.32, 159.99, 160.11; m/z (CI, NH3)
[Found: (M ϩ NH), 502.1925. C22H37NO12 requires 502.1924].
residue was purified by column chromatography (EtOAc–
‘petrol’ 1:1) to afford 17 (2.25 g, 68%), mp 142–143 ЊC; [α]D21
Ϫ10.0 (c 1.3, CHCl3); IR (KBr) νmax 1750, 1614; δH 2.03 (3H, s),
2.09 (3H, s), 2.11 (3H, s), 2.20 (3H, s), 2.42 (3H, d, J 1.3), 4.08–
4.24 (3H, m), 5.16 (1H, d, J 6.0), 5.17 (1H, dd, J 10.6, 4.0), 5.49
(1H, d, J 3.3), 5.51 (1H, dd, J 10.6, 7.3), 6.19 (1H, d, J 1.3), 6.93
(1H, dd, J 8.6, 2.6), 6.99 (1H, d, J 2.6), 7.52 (1H, d, J 8.6);
δC 18.48, 20.39, 20.46 (2C), 20.50, 61.31, 66.72, 68.26, 70.53,
71.32, 98.72 (JC-H 160.18), 103.86, 113.00, 113.72, 115.34,
125.57, 152.08, 154.69, 159.15, 160.60, 169.21, 169.89, 170.04,
170.30; m/z (CI, NH3) [Found: (M ϩ Na), 529.1325.
C24H26NaO12 requires m/z, 529.1322].
2,3,4,6-Tetra-O-acetyl-ꢀ,ꢁ-D-galactopyranose 15
4-Methylumbelliferyl ꢁ-D-galactopyranoside 186d
β--Galactose pentaacetate 14 (5 g, 12.8 mmol) was added to a
solution of ammonia in CH3CN (200 ml), prepared by bubbling
ammonia gas through the solvent at 0 ЊC (20 min). The mixture
was stirred at RT for 24 h. The solvent was removed in vacuo
and the residue was purified by column chromatography
(EtOAc–‘petrol’ 3:2) to afford tetraacetate 15 (4.32 g, 96%),
[α]D19 ϩ31.66 (c 1.2, CHCl3).
Compound 17 (2 g, 3.95 mmol) was O-deacetylated as
described for the preparation of 13 above. Recrystallisation from
ethanol gave the title compound 18 as a white solid (1.17 g,
83%), mp 261–263 ЊC; IR (KBr) νmax 3521, 1721, 1614 cmϪ1
;
δH 2.38 (3H, s), 3.52–3.72 (2H, m), 4.54 (1H, d, J 4.6), 4.66 (1H,
t, J 5.3), 4.90 (1H, d, J 6.0), 4.97 (1H, d, J 7.9), 5.24 (1H, d,
J 5.3), 6.21 (1H, s), 6.99–7.02 (2H, m), 7.65 (1H, d, J 9.2);
δC 18.11, 60.44, 68.12, 70.15, 73.24, 75.74, 100.62, 103.17,
111.67, 113.46, 114.03, 126.41, 153.37, 154.44, 160.17, 160.29;
m/z (CI, NH3) [Found: (M ϩ H), 339.1080. C16H19O8 requires
m/z, 339.1080].
For α isomer, IR (film) νmax 3417, 1747, 1371 cmϪ1; δH 2.07
(3H, s), 2.16 (6H, s), 2.18 (3H, s), 4.13–4.18 (2H, m), 4.21 (1H,
dd, J 7.9, 6.6), 5.07 (1H, d, J 7.9), 5.34 (1H, d, J 4.0), 5.50
(1H, d, J 3.3), 6.32 (1H, d, J1,2 3.3, H-1); δC 20.52, 20.55, 20.59,
20.70, 61.73, 66.06, 67.23, 68.17, 68.35, 90.55 (C-1), 170.10,
170.28, 170.43, 170.60.
For β isomer, δH 1.98 (3H, s), 2.00 (3H, s), 2.03 (3H, s), 2.04
(3H, s), 3.90 (1H, dd, J 7.3, 6.6), 4.05–4.11 (2H, m), 4.57 (1H, d,
J1,2 7.9, H-1), 4.93 (1H, q, J 3.3), 5.29 (1H, d, J 3.3), 5.43
(1H, d, J 2.64); δC 20.44, 20.49, 20.57, 20.65, 60.40, 61.41, 67.12,
70.41, 70.91, 95.85 (C-1), 170.06, 170.20, 170.55, 170.95.
4-Methylumbelliferyl 6-O-(tert-butyldiphenylsilyl)-ꢁ-D-galacto-
pyranoside 19
4-Methylumbelliferyl β--galactopyranoside 18 (1 g, 2.9 mmol)
was dissolved in DMF (10 ml) and the solution was cooled to
0 ЊC. To the resultant solution was added, with stirring, tert-
butyldiphenylsilyl chloride (0.8 g, 2.9 mmol) and imidazole (0.4
g, 5.9 mmol) over a period of 5 min. Stirring was continued for
8 h at RT. The solvent was removed in vacuo, the residue was
dissolved in dichloromethane (50 ml) and this solution was
washed with water (20 ml). The organic layer was dried
(Na2SO4), and the solvent removed in vacuo. Column chromato-
graphy (EtOAc–‘petrol’, 5:1) gave 19 (1.34 g, 79%), [α]D22 Ϫ30.4
(c 3.0, CHCl3); IR (film) νmax 3413, 1727, 1614 cmϪ1; δH 1.03
(9H, s), 2.30 (3H, s), 3.67–3.76 (2H, m), 3.90 (1H, d, J 6.0), 3.94
(2H, s), 4.01 (1H, dd, J 7.9, 3.3), 4.91 (1H, d, J 7.9), 6.09 (1H, d,
J 1.3), 6.84 (1H, d, J 2.6), 6.95 (1H, dd, J 8.6, 2.6), 7.24–7.37
(7H, m), 7.60–7.65 (3H, m), 7.99 (1H, s); δC 18.48, 19.02, 26.67
(2C), 31.40, 63.13, 68.76, 71.10, 73.67, 75.21, 100.56 (JC-H
160.43), 104.24, 112.52, 113.42, 114.77, 125.20, 127.67 (3C),
129.73, 132.76, 132.89, 135.45 (2C), 135.50 (2C), 152.36,
159.83, 160.96, 162.65; m/z (CI, NH3) [Found: (M ϩ H),
577.2263. C32H37O8Si requires m/z, 577.2257].
2-(2Ј,3Ј,4Ј,6Ј-Tetra-O-acetyl-ꢀ,ꢁ-D-galactopyranosyloxy)-1,3,2-
dioxaphosphinane 2-oxide 16ꢀ and 16ꢁ
Treatment of 2,3,4,6-tetra-O-acetyl-α,β--galactopyranose 15
(5 g, 14.4 mmol) with propane-1,3-diyldioxyphosphoryl chlor-
ide (4.5 g, 29.0 mmol) in CH2Cl2 (50 ml) and 1-methylimidazole
(2.35 g, 28.7 mmol), at RT for 16 h as for the preparation of 6
above, afforded the title compounds in the crude state. Chrom-
atographic separation of the resulting residue using (EtOAc–
‘petrol’ 1:1) gave crystalline oxides 16ꢀ, 16ꢁ in a combined
yield of 4.22 g (63%), mp 143–145 ЊC; [α]D21 ϩ55.5 (c 4.0,
CHCl3).
For isomer 16ꢀ, IR (KBr) νmax 1751, 1214 cmϪ1; δH 1.81–1.90
(1H, m, JP-H 15.2, Hax-5), 2.02 (3H, s), 2.05 (3H, s), 2.11 (3H, s),
2.17 (3H, s), 2.25–2.38 (1H, m, JP-H 15.2, Heq-5), 4.04–4.21 (2H,
m), 4.37–4.57 (4H, m), 5.26 (1H, t, J 4.6), 5.30 (1H, dd, J 7.9,
3.3), 5.37 (1H, appt d, J 3.3), 5.51 (1H, appt d, J 3.3), 5.95 (1H,
appt d, J1Ј,2Ј 3.3 H-1Ј); δC 20.46, 20.52 (2C), 20.64, 25.69 (d, JC-P
7.27 C-5), 61.24, 66.80 (d, JC-P 7.79, C-4), 67.21 (C-6), 68.23
(2C), 69.00 (2C), 94.09 (d, JC-P 4.67, C-1Ј), 170.02 (2C), 170.05,
170.32; δP Ϫ10.55 (Found: C, 43.45; H, 5.32; P, 6.88.
C17H25O13P requires C, 43.60; H, 5.38; P, 6.61%).
4-Methylumbelliferyl 6Ј-O-(tert-butyldiphenylsilyl)-3Ј-O-(2Љ,3Љ,
4Љ-tri-O-acetyl-ꢀ-L-fucopyranosyl)-ꢁ-D-galactopyranoside 20
To
a
solution of 2,3,4-tri-O-acetyl-α,β--fucopyranosyl
propane-1,3-diyl phosphate 6/7 (1 g, 2.4 mmol) in dichloro-
methane (10 ml) at Ϫ78 ЊC was added TMSOTf (0.54 g, 2,44
mmol). After 2 min, a solution of compound 19 (1.40 g, 2.44
mmol) in dichloromethane (10 ml) was added to the reaction
flask. The reaction mixture was stirred at Ϫ78 ЊC for 1 h and
was then allowed to warm up to 0 ЊC before quenching with aq.
NaHCO3 (10 ml). The organic layer was dried over (Na2SO4),
and concentrated in vacuo. Column chromatography (EtOAc –
‘petrol’, 6:4) gave 20 as a white crystalline solid (1.01 g, 52%),
mp 109–111 ЊC; [α]D22 Ϫ38.7 (c 3.0, CHCl3); IR (KBr) νmax 3457,
1747, 1614 cmϪ1; δH 1.05 (9H, s), 1.17 (3H, d, J 6.6), 1.98 (3H,
s), 2.04 (3H, s), 2.19 (3H, s), 2.37 (3H, s), 3.70 (1H, dd, J 5.9,
3.3), 3.90–3.96 (3H, m), 4.06–4.16 (3H, m), 4.70 (1H, d, J1,2 7.3,
H-1Ј), 5.02 (1H, br d, J 7.0), 5.08 (1H, d, J1Љ,Љ2 3.3, H-1Љ), 5.13–
5.22 (2H, m), 5.27 (1H, dt, J 7.3, 2.6), 6.17 (1H, s), 6.94 (1H, d,
J 2.0), 6.97 (1H, dd, J 8.6, 2.0), 7.28–7.44 (7H, m), 7.62–7.67
For isomer 16ꢁ, δH 5.22 (1H, dd, J1,2 5.3, 3.3, H-1Ј); δC 96.56
(d, JC-P 4.4, C-1Ј); δP Ϫ10.90.
4-Methylumbelliferyl 2,3,4,6-tetra-O-acetyl-ꢁ-D-galacto-
pyranoside 176d
Propane-1,3-diyl 2,3,4,6-tetra-O-acetyl-β--galactopyranosyl
phosphate 16ꢀ (3 g, 6.4 mmol) was dissolved in CH2Cl2 (30 ml),
and the solution was cooled to Ϫ78 ЊC and treated with
TMSOTf (0.35 g, 1.6 mmol). To the resultant mixture was
added 7-hydroxy-4-methylcoumarin (1.13 g, 6.41 mmol) whilst
the temperature was maintained at Ϫ78 ЊC, and the mixture
was stirred for an additional 0.5 h. Following this the reaction
mixture was warmed to 0 ЊC, neutralised with aq. NaHCO3 (30
ml), and extracted into CH2Cl2 (20 ml), and the extract was
dried over Na2CO3 and concentrated in vacuo. The resultant
2192
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(4H, m); δC 14.04, 15.78, 18.50, 19.04, 20.29, 20.42, 20.47,
20.51, 26.67, 60.29, 62.90, 67.70, 68.59, 69.63, 70.89, 71.87,
75.05, 80.81, 98.79 (C-1Љ), 101.63 (C-1Ј), 104.13, 112.95,
113.17, 115.01, 125.59, 127.58, 127.65 (2C), 127.69, 129.72,
129.74, 132.78, 132.95, 134.73, 135.46, 135.52, 152.02,
159.46, 160.73, 169.44, 169.97, 170.43; m/z (CI, NH3) [Found:
(M ϩ NH4), 866.3480. C44H56NO15Si requires m/z, 866.3419].
Na2SO4, and evaporated in vacuo. Column chromatography
(EtOAc–‘petrol’ 1:4) gave compound 23 as a major (750 mg,
51%) and compound 20 as a minor product (390 mg, 27%), mp
79–81 ЊC; [ꢀ]D20 Ϫ27.32 (c 1.8, CHCl3); IR (KBr) νmax 3452, 1745,
1614 cmϪ1; δH 1.05 (9H, s), 1.16 (3H, d, J 6.6), 2.06 (3H, s), 2.17
(6H, s), 2.37 (3H, s), 3.59 (1H, dd, J 4.0, 2.6), 3.68–3.72 (1H,
m), 3.90–3.99 (2H, m), 4.10–4.22 (3H, m), 5.04 (1H, d, J 7.26,
H-1Ј), 5.17–5.22 (2H, m), 5.27 (1H, dd, J 7.3, 2.6), 5.46 (1H, dd,
J 4.0, 3.3, H-1Љ), 6.16 (1H, s), 6.93 (1H, d, J 1.98), 6.97 (1H, dd,
J 8.5, 2.6), 7.28–7.46 (7H, m), 7.62–7.65 (4H, m); δC 14.09,
15.87, 18.53, 19.07, 20.31, 20.50, 20.54, 20.72, 20.93, 26.70,
60.32, 62.92, 67.74, 68.44, 69.67, 70.79, 71.91, 80.83, 98.83
(C-1Љ), 101.67 (C-1Ј), 104.22, 112.98, 113.22, 115.05, 125.61,
127.68 (2C), 127.73, 127.75, 127.81, 129.75, 129.77, 132.82,
135.47, 135.49, 135.55, 152.05, 152.23, 154.75, 159.50, 169.01,
170.01, 170.42; m/z (CI, NH3) [Found: (M ϩ NH4), 866.5243.
C44H56NO15Si requires m/z, 866.3075].
4-Methylumbelliferyl 3Ј-O-(2Љ,3Љ,4Љ-tri-O-acetyl-ꢀ-L-fuco-
pyranosyl)-ꢁ-D-galactopyranoside 21
To a THF solution (5 ml) of silyl compound 20 (0.5 g, 0.58
mmol) was added tetrabutylammonium fluoride (0.1 M solu-
tion in THF; 15 ml) and the mixture was stirred for 12 h at RT.
The solvent was removed in vacuo, the residue was dissolved in
CH2Cl2 (10 ml), and the solution was washed with water (10
ml), dried over Na2SO4, and concentrated. The resultant
material was purified by column chromatography (EtOAc–
‘petrol’ 3:2) and gave thiol 21 (250 mg, 69%), [α]D23 Ϫ28.4 (c 1.8,
CHCl3); IR (film) νmax 3437, 1745, 1612 cmϪ1; δH 1.26 (3H, d,
J 7.3), 1.98 (3H, s), 2.04 (3H, s), 2.19 (3H, s), 2.40 (3H, s), 3.72–
3.78 (2H, m), 3.86–4.03 (2H, m), 4.08 (1H, d, J 7.3), 4.13 (1H,
dd, J 7.3, 2.6), 4.28 (1H, dd, J 7.3, 6.6), 4.71 (1H, d, J1Ј,2Ј 7.9,
H-1Ј), 5.05–5.10 (2H, m), 5.14 (1H, appt d, J 7.9), 5.27 (1H, d,
J1Љ,2Љ 2.6, H-1Љ), 6.18 (1H, s), 6.95–7.00 (2H, m), 7.51 (1H, d,
J 9.9); δC 15.84, 18.56, 20.30, 20.46, 20.55, 62.17, 67.90, 68.32,
68.65, 69.72, 69.85, 71.72, 74.76, 80.63, 98.86 (JC-H 167.70,
C-1Љ), 101.64 (JC-H 161.99, C-1Ј), 104.10, 113.04, 113.23, 115.16,
125.70, 152.17, 154.84, 159.45, 160.81, 169.45, 170.02, 170.46;
m/z (CI, NH3) [Found: (M ϩ NH4), 628.1928. C28H38NO15
requires m/z, 628.1928].
Acknowledgements
We thank the EPSRC for access to the mass spectrometry
service at the University of Wales, Swansea (Director,
Prof. D. E. Games).
References
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4-Methylumbelliferyl 1-O-(ꢀ-L-fucopyranosyl)-ꢁ-D-galacto-
pyranoside 22
The disaccharide 21 (0.2 g, 0.32 mmol) was O-deacetylated as
described for the preparation of compound 13 above. Recrystal-
lisation from EtOH afforded the title compound 22 as a white
solid (138 mg, 87%), mp 287–289 ЊC; [α]D21 Ϫ27.3 (c 0.2, H2O); IR
(KBr) νmax 3440, 1698, 1619 cmϪ1; λmax (H2O) 320, 292, 252 nm;
δH (DMSO-d6) 1.06 (3H, d, J 6.6), 2.40 (3H, s), 3.53–3.59 (2H,
m), 3.63 (1H, dd, J 9.9, 3.3), 3.71 (1H, m), 3.78 (1H, dd, J 9.9,
7.3), 4.40 (1H, d, J 7.3), 4.45 (1H, q, J 3.3), 4.51 (1H, d, J 1.3),
4.69–4.72 (2H, m), 4.94 (1H, d, J 4.0), 5.08 (1H, d, J 6.6), 6.24
(1H, s), 7.00–7.10 (2H, m), 7.67 (1H, d, J 8.6); δC (DMSO-d6)
16.40, 18.08, 60.34, 67.33, 70.21 (2C), 70.97, 71.49, 73.32, 75.57,
78.31, 100.08 (JCH 173.7), 103.04 (JCH 159.4), 103.96, 111.71,
113.96, 114.27, 126.23, 153.31, 154.24, 160.07, 160.25; m/z (CI,
NH3) [Found: (M ϩ NH4), 502.1920. C22H32NO12 requires m/z,
502.1924].
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4-Methylumbelliferyl 6Ј-O-(tert-butyldiphenylsilyl)-2Ј-O-
(2Љ,3Љ,4Љ-tri-O-acetyl-ꢀ-L-fucopyranosyl)-ꢁ-D-galactopyranoside
23
To a solution of the galactopyranoside 19 (1.01 g, 1.74 mmol)
in CH2Cl2 (10 ml), containing Et4NϩBrϪ (0.36 g, 1.74 mmol)
and molecular sieves (4 g), was added 2,3,4-tri-O-acetyl-α--
fucopyranosyl bromide 3 (0.62 g, 1.74 mmol). The resulting
mixture was stirred at RT for 48 h. The solid residue was
removed by passage through a pad of Celite and the filtrate was
washed with water (10 ml). The CH2Cl2 layer was dried over
J. Chem. Soc., Perkin Trans. 1, 2000, 2187–2193
2193