Synthesis of 2,5-anhydro-(β-D-glucopyranosyluronate)- and (α-L-idopyranosyluronate)-D-mannitol hexa-O-sulfonate hepta sodium salt

Article abstract of DOI:10.1016/j.carres.2004.03.006

Glycosidation of 2,5-anhydro-1,6-di-O-benzoyl-D-mannitol with methyl(2,3,4-tri-O-acetyl-α-D-glucopyranosyl-1-O-trichloroacetimidate) uronate in the presence of trimethylsilyl triflate afforded the corresponding 3-O-β-glycoside, which after deprotection wa

Full text of DOI:10.1016/j.carres.2004.03.006

Carbohydrate
RESEARCH
Carbohydrate Research 339 (2004) 1569–1579
Note
Synthesis of 2,5-anhydro-(b- -glucopyranosyluronate)- and
D
(a-L
-idopyranosyluronate)- -mannitol hexa-O-sulfonate
D
hepta sodium saltq
*
ꢀ
ꢀ
ꢀ
Janos Kuszmann, Gabor Medgyes and Sandor Boros
IVAX Drug Research Institute, PO Box 82, H-1325 Budapest, Hungary
Received 14 January 2004; accepted 9 March 2004
Dedicated to the memory of Christian Pedersen who passed away September 14, 2003
Abstract—Glycosidation of 2,5-anhydro-1,6-di-O-benzoyl-
D
-mannitol with methyl(2,3,4-tri-O-acetyl-a-
D
-glucopyranosyl-1-O-tri-
chloroacetimidate)uronate in the presence of trimethylsilyl triflate afforded the corresponding 3-O-b-glycoside, which after depro-
tection was converted into its hexa-O-sulfate with DMFÆSO3 to give after treatment with sodium acetate and subsequent
saponification of the methyl ester with sodium hydroxide the hepta sodium salt of 2,5-anhydro-3-O-(b-
D
-glucopyranosyl uronate)-
D
-mannitol hexa-O-sulfate. Glycosidation of the same acceptor with the a-thiophenylglycoside of methyl 2,4-di-O-acetyl-3-O-
benzyl-
L
-idopyranosyl uronate in the presence of NIS/TfOH afforded the corresponding 3-O-a-glycoside in very low yield, therefore
-idopyranose was used as donor. The terminal hydrox-
ymethyl group of the obtained disaccharide was subsequently oxidised with NaOCl/TEMPO and the obtained iduronic acid
the a-thiophenylglycoside of 2-O-acetyl-2,4-O-benzylidene-3-O-benzyl-
L
derivative was converted into the hepta sodium salt of 2,5-anhydro-3-O-(-a-
with DMFÆSO3 and subsequent treatment with sodium acetate.
Ó 2004 Elsevier Ltd. All rights reserved.
L-idopyranosyluronate)-D-mannitol hexa-O-sulfonate
Keywords:
D-Glucuronic acid derivatives; L-Iduronic acid derivatives; Supersulfated disaccharides
Heparin is a member of the large family of glycosa-
minoglycans, which are polyanionic, complex carbohy-
drate macromolecules. It was discovered in 1916 and
became well known as an antithrombotic agent, which
has been used clinically since 1935.1 However, this
macromolecule possess other very important and sig-
nificant biological activities too, among others antiin-
flammatory, antiallergic and even antiasthmatic
properties.2–5 Despite the fact that heparin is con-
structed from a repeating disaccharide building block
containing an uronic acid attached to glucosamine at
O-4, it is a very complex molecule, as the uronic acid
residue can be either b-
acid both of which can be sulfated at O-2. Furthermore
the a- -glucosamine unit may either be N-acetylated or
D
-glucuronic- or a-L-iduronic
D
N-sulfated, both are 6-sulfated and may also be 3-sul-
fated. It was presumed that the aforementioned different
biological activities can be attributed to different regions
of the macromolecules, but their microheterogeneity
made the exact structure elucidation very difficult. It
took decades until the researchers were able to prove,6;7
that a pentasaccharide unit 1 is responsible for the an-
tithrombotic effect (Fig. 1). As far as the whole molecule
of heparin is concerned, it should be mentioned that the
ratio of L-iduronic to D-glucuronic acid varies between
9:1 and 7:3, depending of the source of isolation.8 The
antiinflammatory, antiallergic and antiasthmatic activity
is however independent from the anticoagulant activity
of native heparin, and is displayed by low, and even
ultraslow molecular weight heparin fragments, obtained
qSupplementary data associated with this article can be found in the
online version at doi:10.1016/j.carres.2004.03.006
* Corresponding author. Tel.: +36-1-399-3300; fax: +36-1-399-3356;
e-mail: janos.kuszmann@idri.hu
0008-6215/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2004.03.006

1570
J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
ROH2C
O
NaOOC
O
ROH2C
O
NaOOC
ROH2C
O
O
O
O
O
O
*
O
O
*
NHR
HO
OR
NHR HO
RO
OH
n
NHX HO
HO
IdoA
GlcN
GlcN
GlcA
GlcN
1 R = SO3Na, X = Ac/SO3Na
RO
RO
O
NaOOC
NaOOC
O
O
O
O
O
RO
RO
RO
OR
OR
OR
OR
OR
RO
OR
2 R = H
3 R = SO3Na
4 R = H
5 R = SO3Na
Figure 1.
by degradation of the original GAGs.9;10 Recently it was
claimed by Ahmed and Smith,11 that hypersulfated
disaccharides, obtained by degradation of heparin with
HNO2 subsequent reduction by NaBH4 followed by
O-sulfation possess pronounced antiasthmatic activity.
It is well known,12 that the primary degradation product
obtained by depolymerisation of GAGs by HNO2 when
treated with NaBH4 results in a mixture, containing
the two disaccharides 2 and 4. Accordingly, the struc-
ture of the main components obtained after sulfation
corresponds to the hepta sodium salt of 2,5-anhydro-3-
type glycoside containing the 3-O-acetate group at the
aglycon unit (10)––as well as the expected glycoside 12
could be separated by column chromatography (Scheme
1). The latter compound was obtained as a syrup in a
relatively low yield (36%) and according to NMR its
purity was ꢁ60%. For further purification, it was con-
verted into its crystalline tribenzoate 13. For avoiding
the migration of the 2-O-acetyl group of the donor to
the acceptor, the same glycosylation reaction was re-
peated using tribenzoate 9 as acceptor––which was ob-
tained as a by-product14 in the benzoylation reaction of
O-(b-
luronate)-
D
-glucopyranosyluronate)- and (a-
L
-idopyranosy-
-mannitol hexa-O-sulfate 3 and 5, respec-
2,5-anhydro-D
-mannitol.13;17 Despite the fact, that in
D
this reaction crude imidate was applied, the yield of the
obtained pseudotrisaccharide (counted on the imidate
content) was excellent (92%), but the isolated material
did not crystallise and was not identical with 13. De-
tailed investigation of the isolated product by NMR
revealed the fact, that instead of 13 the ortho-ester 11
was formed. This could not be rearranged into the for-
mer on treatment with TfOH or BF3ÆEt2O in CH2Cl2 as
only decomposition took place (Scheme 1).
tively (Fig. 1). As their separation represents a very
difficult problem, it was decided to synthesise both of
them for comparing their biological activity.
1. Synthesis of the glucuronic acid derivative 3
For the coupling reaction, 1,6-di-O-benzoate 713;14 was
For the obtention of the target molecule 3, the tri-
ꢀ
used as acceptor and methyl (2,3,4-tri-O-acetyl-a-D-
glucopyranosyl bromide)uronate15 as the donor mole-
cule in the presence of mercury cyanide as promoter in
acetonitrile as solvent at ꢀ5 °C. No reaction took place
according to TLC, therefore the temperature was raised
to 20 °C and later to 50 °C, but only decomposition of
the acetobromo derivative took place and the acceptor
molecule remained unchanged.
benzoate 13 was submitted to Zemplen deacylation, which
was a very slow process, as the isolated 3-O-benzoyl
group is very resistant towards transesterification.18 The
obtained hexahydroxy compound 14 was converted with
DMFÆSO3 into its hexa-O-sulfate, which after treatment
with sodium acetate afforded the hexa-O-sulfate hexa
sodium salt 15. Finally the terminal methyl ester was
saponified with NaOH to give the corresponding hepta-
sodium salt 3, which was submitted to biological testing.
It should be mentioned, that according to NMR the
glucuronide part of this molecule adopts a rather dis-
torted boat conformation, due to the electrostatic
repulsion of the adjacent O-sulfate groups in position 20,
Next, the more active imidate 616 was used as donor
1,6-di-O-benzoate 7 as acceptor and trimethylsilyl tri-
fluoromethanesulfonate as promoter. The reaction was
carried out in CH2Cl2 at ꢀ40 °C and was finished in
ꢁ5 min. From the resulting complex mixture, the 3-O-
acetate of the acceptor anhydride (8)––an ortho-ester

J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
1571
CCl3
MeOOC
AcO
O
O
O
O
BzO
OBz
BzO
OBz
NH
+
OAc
HO
OH
HO
OAc
OAc
8
7
6
+
BzO
O
O
O
BzO
OBz
MeOOC
O
O
O
HO
OBz
AcO
9
OAc
OBz
OAc
10
BzO
O
O
BzO
OBz
O
MeOOC
AcO
O
O
O
MeOOC
O
O
OR
OBz
OBz
OAc
AcO
OAc
11
OAc
12 R = H
13 R = Bz
O
O
RO
OR
NaO3SO
O
OSO3Na
OSO3Na
MeOOC
O
O
OR
NaOOC
NaO3SO
O
RO
OR
OSO3Na
OSO3Na
OR
14 R = H
15 R = SO3Na
3
Scheme 1.
30 and 40. This is evident from the value of the corre-
column chromatography: 1,2-(R):5,6-(S)-di-O-benzylid-
ene- -idofuranose (17) a 1:1 mixture of the aforemen-
0
0
0
0
0
0
sponding coupling constants (J2 ;3 3.4, J3 ;4 5.3, J4 ;5
3.8 Hz) which in the case of the unsubstituted starting
L
tioned compound and the corresponding 1,2-(R):5,
6-(R)-di-O-benzylidene isomer (17 þ 18), 1,2-(R):4,6-
0
0
0
0
material 15 had much higher values (J2 ;3 8.2, J3 ;4 9.0,
0
0
J4 ;5 9.3 Hz) as expected for the normal chair confor-
(R)-di-O-benzylidene-L-idopyranose (19) and the needed
4,6-(R)-O-benzylidene-L-idopyranose (20) in yields of
4
mation C1.
1%, 3%, 7% and 58%, respectively (Scheme 2). The
configuration of the benzylidene groups was determined
by NMR using NOE measurements. The monobenzy-
lidene derivative 20 gave on acetylation the known19 1,
2-di-O-acetate 21 as an anomeric mixture. The O-ben-
zylidene group of the latter was split off without sepa-
ration of the anomers with aqueous trifluoroacetic acid
in CH2Cl2 solution and the obtained 4,6-dihydroxy
derivative 22 (61%) gave on treatment with tert-butyl-
dimethylsilyl chloride in the presence of Et3N the 6-O-
silylated derivative 23 containing the a/b-anomers in a
ratio of 1:2. When acetic anhydride was added after
silylation to the same reaction mixture, no acetylation
2. Attempted synthesis of 5 using an
derivative as donor
L-iduronic acid
In our first attempt we decided to use an L-iduronic acid
thioglycoside as donor, which was synthesised by using
the method described by Tabeur et al.19 for the synthesis
of a 4-O-levulinoyl analogue. Accordingly 3-O-benzyl-L-
idose 16 was prepared by the method elaborated by van
Boeckel et al.20 and was treated with benzaldehyde in the
presence of trifluoroacetic acid.19 From the resulting
mixture the following components could be separated by

1572
J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
O
O
Ph
Ph
S
R
O
O
O
OH
OH
HO
O
O
+
O
BnO
HO
O
BnO
O
R
R
OBn
O
Ph
Ph
16
17
18
O
OH
OH
O
O
OAc
OAc
O
R
O
O
O
+
Ph
R
R
R
O
Ph
O
Ph
O
Ph
O
OBn
OBn
OBn
20
21
19
O
O
O
OAc
R1O
R2O
O
SPh
OAc
O
OAc
OAc
R1O
R2O
MeO
OAc
AcO
OBn
OBn
31
OBn
22 R1 = R2 = H
27 R1 = Me; R2 = H
28 R1 = H; R2 = Ac
29 R1 = Me; R2 = Ac
30 R1 = R2 = H
23 R1 = TBDMSi; R2 = H
24 R1 = TBDMSi; R2 = Ac
25 R1 = Ac; R2 = H
+
6
O
26 R1 = H; R2 = Ac
BzO
O
OBz
O
O
OR
MeO
AcO
OAc
OBn
32
Scheme 2.
took place. Finally isolated 23 could be converted into
triacetate 24 on treatment with acetyl chloride in pyri-
dine. The two anomers of 24 could be partially sepa-
rated by column chromatography, but the further
reactions were carried out with the anomeric mixture.
When the 6-O-silyl group was removed from 24 by
treating its methanolic solution with aqueous HCl at
0 °C, besides hydrolysis a partial 4-O ! 6-O acetyl
migration took place resulting in anomeric mixtures of
two isomeric tetraacetates 25 and 26. They could be
separated by column chromatography yielding the ne-
eded 6-OH isomer 26 in a yield of 40%. Oxidation of the
terminal hydroxymethyl group was carried out with
sodium hypochlorite in the presence of TEMPO21 and
the sodium salt of the formed carboxylic acid 28 was
treated with methyl iodide affording the methyl ester 29
in an overall yield of 24% counted on 22. This low
overall yield could be increased to 42% by oxidising 22
directly without protecting the secondary 4-OH group.
The formed carboxylic acid 30 was converted into its
methyl ester 27, which on acetylation gave 29. Treat-
ment of triacetate 29 with thiophenol in the presence of
BF3ÆEt2O afforded the thioglycoside 31 as a-anomer in
moderate yield (52%). This was used as donor for the
glycosidation of the 1,6-di-O-benzoate 7 applying NIS
as activator and a catalytic amount of TfOH as pro-
moter and carrying out the reaction at ꢀ40 °C in
CH2Cl2. The formed protected disaccharide 32 was
obtained after column chromatography as a-anomer in
a very low yield (21%). As the yield could not be
increased by changing the reaction conditions, this
approach had to be abandoned.
3. Synthesis of 5 using an L-idopyranose thioglycoside
derivative as donor
In our further attempts, 3-O-benzyl-L-idopyranose-per-
acetate 3320 was converted into its 1-bromide 3420, which
was coupled with dibenzoate 7 using Helferich’s condi-
tions, which according to literature data20 were suc-
cessfully applied in the synthesis of the corresponding
levoglucosan disaccharide. However in our case no
reaction took place at room temperature only a slow

J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
1573
decomposition of 34 was observed. Therefore 33 was
treated with thiophenol in the presence of BF3ÆEt2O19
affording thioglycoside 35 as an a=b ꢁ 5 : 1 anomeric
mixture, which could be separated by column chroma-
tography (Scheme 3). Deacetylation of the major ano-
mer 35a afforded 36a, which was converted into the
corresponding 4,6-O-benzylidene derivative 37a on
treatment with benzaldehyde dimethylacetal. When, in
the same reaction sequence the anomeric mixture of 35
was applied as starting material, both anomers 37a and
37b were obtained, which could be separated by column
chromatography. Acetylation of 37a afforded the 2-O-
acetate 38a, which could be obtained by an alternative
approach using benzylidene diacetate 21 as starting
material and converting it into 38a by treatment with
thiophenol in the presence of BF3ÆEt2O. Nevertheless
the overall yields of these two approaches counted on
the tetraacetate 33 were almost the same (Scheme 3).
Condensation of the thioglycoside 38a with the
aglycon 6 in CH2Cl2 at low temperature (ꢀ40 °C) using
NIS as activator and TfOH as promoter afforded the
needed glycoside 39 as a-anomer in excellent yield
(81%). The benzylidene and benzyl group of the latter
were removed by hydrogenation over Pd/C and the
obtained trihydroxy derivative 45 was converted into its
6-O-t-butyldimethylsilyl derivative, which was not iso-
lated but converted directly into its 4,4,40-tri-O-benzoyl
derivative 44. The terminal silyl group of 44 was re-
moved by treatment with aqueous sulfuric acid in EtOH
to yield the 6-OH compound 44 in excellent yield. Par-
tial oxidation of the terminal hydroxymethyl group of
44 was carried out with NaOCl in the presence of
TEMPO21 affording after column chromatography 40 in
satisfactory yield (70%) as a ꢁ1:3 mixture of the free
carboxylic acid and its sodium salt. This was converted
into its polysulfate with SO3ÆDMF to yield the hepta
sodium salt 5 after removing the excess of sulfate ions
with Sr(OAc)2 and treatment of the solution with a
CHELEX 100 (Na) resin.
4. Experimental
4.1. General methods
Organic solutions were dried over MgSO4 and concen-
trated under diminished pressure at or below 40 °C.
TLC: E. Merck precoated Silica Gel 60 F254 plates, with
EtOAc (A), EtOAc–hexane mixtures (B, 1:1; C, 1:2; D,
1:3; E, 1:5; F, 2:1; G, 2:3; H, 3:1), EtOAc–EtOH mixture
(I, 5:1); detection by spraying the plates with a 0.02 M
solution of I2 and a 0.3 M soln of KI in 10% aqueous
H2SO4 solution followed by heating at ca. 200 °C. For
column chromatography Kieselgel 60 was used. The mp
are uncorrected. Optical rotations were determined on
1.0% solutions in CHCl3 at 20 °C unless stated other-
wise. The NMR spectra were recorded on a Bruker
Avance 500 spectrometer at 500 (1H, see Supplementary
Material, Tables 1,2,4 and 5) and 125 (13C see Supple-
mentary Material, Tables 3 and 6) MHz, respectively, at
ambient temperature. The chemical shifts were refer-
enced to dTMS ¼ 0 ppm. The solvent is indicated at the
1H NMR spectral data. For structure determination 1H,
21
O
BzO
O
OBz
O
X
O
SPh
OR
RO
O
+ 7
O
OH
O
RO
OR
Ph
O
OBn
Ph
O
OAc
OBn
OBn
33 R = Ac, X = OAc
34 R = Ac, X = Br
35 R = Ac, X = SPh
36 R = H, X = SPh
37 R = H
38 R = Ac
39
O
O
R2O
O
OR2
O
BzO
O
OBz
BzO
O
OBz
OR2
O
O
OR2
R1O
O
R1O
R2O
O
OH
HO
R2O
OR3
OAc
HO
OAc
OR2
OR2
OH
40 R1 = H, R2 = Bz, R3 = Ac
41 R1 = Na, R2 = R3 = H
42 R1 = TBDMSi, R2 = H
43 R1 = TBDMSi, R2 = Bz
44 R1 = H, R2 = Bz
45
5 R1 = Na, R2 = R3 = SO3Na
Scheme 3.

1574
J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
1H COSY, TOCSY, HMQC, HMBC as well as selective
1D TOCSY and NOESY spectra were recorded.
tially sulfated derivatives); ½aꢂ ꢀ5 (c 1, water). Anal.
D
Calcd for C12H13O29S6Na7: C, 14.79; H, 1.34; Na,
16.51; S, 19.74. Found: C, 14.43; H, 1.48; Na, 16.44; S,
19.52.
4.2. 2,5-Anhydro-3-O-(b-D-glucopyranosyl uronate)-D-
mannitol hexa-O-sulfate hepta sodium salt (3)
4.4. Methyl(2,3,4-tri-O-acetyl-a- -glucopyranosyl-1-O-
D
trichloroacetimidate)uronate (6)
To a stirred slurry of DMFÆSO3 (48%, 1.7 g, 10 mmol) in
DMF (3 mL) a soln of 14 (0.35 g, 1 mmol) in DMF
(3 mL) was gradually added at ꢀ20 °C at such a rate to
keep the temperature below ꢀ15 °C. After 15 min, the
temperature of the mixture was raised to ꢀ5 °C and kept
there for 45 min. Thereafter it was cooled to ꢀ25 °C and
EtOH (0.5 mL) was added at such a rate to keep the
temperature below ꢀ15 °C. Thereafter the mixture was
poured into a stirred and cooled (ꢀ5 °C) soln of NaOAc
(2 g) in MeOH (20 mL). The resulting precipitate was
filtered and washed with MeOH. The solid residue was
dissolved in water (5 mL), the pH of the solution was
adjusted to 8–9 with M NaOH. Thereafter M NaOH
(1 mL) was added to hydrolyse the formed methyl ester
15. The mixture was kept for 15 h at rt thereafter it was
diluted with water (25 mL) and a soln of aq M Sr(OAc)2
was added until no more precipitate (SrSO4) was formed
(ꢁ10 mL). The precipitate was filtered off and the filtrate
was submitted to a column loaded with CHELEX 100
(Na form) (10 mL) for removing Sr ions. The column
was eluted with distilled water and the eluate was con-
centrated. The residue was filtered with EtOH to yield 3
To a stirred soln of methyl(2,3,4-tri-O-acetyl-a-D-glu-
copyranose)uronate16 (24.7 g, 74 mmol) in 1,2-dichloro-
ethane (120 mL), trichloroacetonitrile (25 mL) and
K2CO3 (25 g) were added at rt. The mixture was stirred
for 3 h, thereafter the solid material was filtered off and
the filtrate was concentrated. According to NMR spec-
troscopy, the imidate content of the residue (34.6 g,
98%) was ꢁ50%. It could be purified by column chro-
matography (C ! B) and the residue obtained on con-
centration of the fractions having Rf 0.6 (C) gave after
recrystallisation from 2-propanol pure 6 (5.8 g, 16%),
mp 114–115 °C, lit.16 mp 108 °C.
4.5. 2,5-Anhydro-1,6-di-O-benzoyl- (7) and 1,3,6-tri-O-
benzoyl-D-mannitol (9)
To a stirred soln of 2,5-anhydro-
D
-mannitol13;17 (25.5 g,
15.5 mmol) in pyridine (250 mL), a soln of benzoyl
chloride (45 mL, 39 mmol) in CH2Cl2 (200 mL) was ad-
ded dropwise at 0 °C. The mixture was stirred at 0 °C for
1.5 h and then kept at 20 °C for 30 min. Thereafter it was
poured into water, the separated aq soln was extracted
with CH2Cl2 and the combined organic solutions gave
after usual processing and concentration a residue,
which was submitted to column chromatography. As
eluent first solvent C was applied for removing the by-
products (Rf 0.9 and 0.6) and then A for eluting the
product. Concentration of the latter fraction gave crude
(0.75 g, 79%); ½aꢂ þ15 (c 1, water). Anal. Calcd for
D
C12H13O29S6Na7: C, 14.79; H, 1.34; Na, 16.51; S, 19.74.
Found: C, 14.58; H, 1.72; Na, 16.42; S, 19.55.
4.3. 2,5-Anhydro-3-O-(-a-L-idopyranosyluronate)-D-
mannitol hexa-O-sulfate hepta sodium salt (5)
7 (33.5 g, 58%), mp 99–101 °C (toluene); Rf 0.5 (F); ½aꢂ
D
To a stirred slurry of 48% SO3ÆDMF (30 g, 175 mmol) in
dry DMF (50 mL) the sodium salt 41 (5.0 g, 14 mmol)
was added below ꢀ15 °C. Thereafter the temperature
was raised to ꢀ5 °C and kept there for 45 min. The
formed clear soln was kept at 0 °C for 45 min and was
then poured into a cooled (0 °C) soln of NaHCO3 (28 g)
in water (350 mL). The soln was neutralised with M
H2SO4 and concentrated. The residue was filtered and
washed with MeOH. The resulting crude material was
dissolved in water (250 mL) and a soln of aq M
Sr(OAc)2 was added until no more precipitate (SrSO4)
was formed (ꢁ120 mL). The precipitate was filtered off
and the filtrate was submitted to a column loaded with
CHELEX 100 (Na form) (20 mL) for removing Sr ions.
The column was eluted with distilled water and the
eluate was concentrated. The residue was filtered with
EtOH to give 5 (12.2 g, 90%) which, according to NMR
spectroscopy, contained 0.2 equiv EtOH and 0.75 equiv
NaOAc but was free from any other by-product (par-
þ21 (c 1, CHCl3); ½aꢂ þ29 (c 1, MeOH), lit.13 mp 100–
D
102 °C, ½aꢂ þ31 (c 1.5, MeOH).
D
The residue, obtained on concentration of the frac-
tions containing the by-products, afforded a syrup (16 g)
from which the tribenzoate 9 (9.9 g, 13.3%) could be
obtained after repeated column chromatography with
solvent B; Rf 0.5 (C); mp 75–80 °C (ether–hexane); ½aꢂ
D
þ43 (c 1, CHCl3). Lit.14 mp 80–84 °C; ½aꢂ þ54 (c 0.1,
D
CHCl3).
4.6. Reaction of trichloroimidate 6 with dibenzoate 7
A soln of 7 (0.74 g, 2 mmol) and 6 (0.96 g, 2 mmol) in
CH2Cl2 (25 mL) was stirred in the presence of molecular
ꢁ
sieve (4 A) (5 g) for 2 h. Thereafter the mixture was
cooled to ꢀ40 °C and TMSOTf (0.1 mL) was added.
After 5 min the reaction was stopped by adding Et3N
(0.5 mL). After dilution with CH2Cl2 (25 mL) it was
washed with 5% aq NaHCO3 and water, dried and

J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
1575
concentrated. The residue was submitted to column
chromatography (B). Concentration of the fraction
having Rf 0.8 afforded 3-O-acetyl-1,6-dibenzoyl-2,5-an-
cation exchange resin, filtered and concentrated. The
residue was dissolved in water, extracted with ether and
the aq soln was concentrated to give 14 (0.5 g, 93%) as a
syrup. Rf 0.3 (H). Anal. Calcd for C13H22O11: C, 44.07,
H, 6.26. Found: C, 43.88, H, 6.52.
hydro-D-mannitol (8) (0.1 g, 12%). Anal. Calcd for
C22H22O8: C, 63.76; H, 5.35. Found: C, 63.67; H, 5.57.
Concentration of the fraction having Rf 0.65 gave
methyl 3,4-di-O-acetyl-1,2-(S)-O-[10-O-(3-O-acetyl-2,5-
4.10. Reaction of 3-O-benzyl-L-idose (16) with benzalde-
hyde
anhydro-1,6-di-O-benzoyl-
a-
Calcd for C35H38O17: C, 57.53; H, 5.24. Found: C, 57.45;
D-mannito-4-yl)-ethylidene]-
D
-glucopyranuronate 10 (0.15 g, 11%); ½aꢂ þ12. Anal.
D
To a stirred soln of 1620 (3.1 g, 11.5 mmol) in benzal-
dehyde (10 mL), CF3COOH (0.5 mL) was added. The
mixture was stirred at 20 °C for 3 h, then it was neu-
tralised with Et3N (1.5 mL), diluted with CH2Cl2,
washed with water, dried and concentrated. The residue
was treated with hexane (2 ꢃ 25 mL), the hexane soln
was decanted, and the residue (4.3 g) submitted to col-
umn chromatography using first E and then B for elu-
tion.
H, 5.38.
Concentration of the third fraction having Rf 0.5 gave
2,5-anhydro-1,6-di-O-benzoyl-4-O-(methyl 2,3,4-tri-O-
acetyl-
D
-glucopyranosyl
uronate)-
D
-mannitol
(12)
(0.5 g, 36%), the purity of which was ꢁ60% according to
NMR.
4.7. Benzoylation of 12
Concentration of the first fraction gave 3-O-benzyl-
-idofuranose
(30 mg, 1%), Rf 0.3 (E). Anal. Calcd for C27H26O6: C,
72.63; H, 5.87. Found: C, 72.55; H, 5.96.
Concentration of the second fraction gave a 1:1
mixture of 17 and the corresponding 3-O-benzyl-1,2-
(R):5,6-(R)-di-O-benzylidene isomer (18), (150 mg, 3%),
Rf 0.3 (E). Anal. Calcd for C27H26O6: C, 72.63; H, 5.87.
Found: C, 72.47; H, 5.99.
To a stirred and cooled (0 °C) soln of crude 12 (1.5 g) in
pyridine (10 mL), benzoyl chloride (0.5 mL) was added
at such a rate to keep the temperature below 20 °C. After
1.5 h at rt the mixture was diluted with CH2Cl2 to give
after usual processing and concentration of the organic
soln 2,5-anhydro-1,3,6-tri-O-benzoyl-4-O-(methyl 2,3,4-
1,2-(R):5,6-(S)-di-O-benzylidene-
L
(17)
tri-O-acetyl-D-glucopyranosyl uronate)-D-mannitol 13
(0.9 g, 52%), mp 140–141 °C (EtOH), Rf 0.6 (B); ½aꢂ
D
ꢀ18. Anal. Calcd for C40H40O17: C, 60.60; H, 5.09.
Concentration of the third fraction gave 3-O-benzyl-
-idopyranose
Found: C, 60.72; H, 5.12.
1,2-(R):4,6-(R)-di-O-benzylidene-
L
(19),
(360 mg, 7%), Rf 0.2 (E), Rf 0.8 (B). Anal. Calcd
for C27H26O6: C, 72.63; H, 5.87. Found: C, 72.47; H,
5.56.
Concentration of the last fraction, using solvent B for
elution gave 3-O-benzyl-4,6-(R)-O-benzylidene-L-ido-
4.8. Reaction of trichloroimidate 6 with tribenzoate 9
To a stirred soln of crude imidate 6 (purity ꢁ50%,12 g,
12.5 mmol) and tribenzoate 9 (5.7 g, 12 mmol) in CH2Cl2
ꢁ
(100 mL) molecular sieve (4 A) (20 g) was added. After
pyranose (20) (2.4 g, 58%), Rf 0.5 (B) which according to
NMR contained the a/b-anomers in a ratio of 3:7.
According to lit.19 the two anomers were isolated as a
1:1 mixture in a yield of 49%.
30 min the mixture was cooled to ꢀ35 °C and TMSOTf
(0.5 mL) was added. The temperature was kept at
ꢀ30 °C for 8 min, thereafter the reaction was quenched
with Et3N (1 mL), diluted with CH2Cl2, washed with
water, dried and concentrated. The residue was sub-
mitted to column chromatography (G) to give after
concentration of the fractions having Rf 0.5 a syrup (8 g,
84%) the structure of which according to NMR corre-
sponded to methyl 3,4-di-O-acetyl-1,2-(S)-O-[10-O-(2,5-
4.11. Conversion of 20 into 1,2,4-tri-O-acetyl-3-O-benzyl-
6-O-t-butyldimethylsilyl-L-idopyranose (24)
A soln of 20 (13 g, 35.5 mmol) in pyridine (50 mL) and
acetic anhydride (30 mL) was kept at rt for 20 h (Rf
0.2 ! 0.6, EtOAc–hexane 1:2), to give after usual pro-
cessing crude 1,2-di-O-acetyl-3-O-benzyl-4,6-(R)-O-
anhydro-1,3,6-tri-O-benzoyl-
a-
for C40H40O17: C, 60.60; H, 5.09. Found: C, 60.43; H,
5.18.
D-mannito-4-yl)-ethylidene]-
-glucopyranuronate 11; ½aꢂ þ11. Anal. Calcd
D
D
benzylidene-L-idopyranose 21 (13.9 g, 80%) as syrup
containing according to NMR spectroscopy the a,b-
anomers in a ratio of 3:7.
To a soln of crude 21 (2.9 g) in CH2Cl2 (300 mL)
CF3COOH (10 mL) and water (5 mL) were added at
0 °C. The mixture was kept at this temperature for 4 h
(Rf 0.6 ! 0.05, C) and was then treated with a cold
(0 °C) aq NaHCO3 soln. The organic soln was washed
4.9. 2,5-Anhydro-3-O-(methyl b-
nate)- -mannitol (14)
D-glucopyranosyl uro-
D
A stirred slurry of 13 (1.2 g, 1.5 mmol) in MeOH (20 mL)
and 2 M methanolic NaOMe (0.3 mL) was stirred at
45 °C for 5 h. The cooled soln was neutralised with a

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J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
with water, dried and concentrated to give after column
chromatography 1,2-di-O-acetyl-3-O-benzyl- -idopyra-
4.13. Methyl 1,2,4-tri-O-acetyl-3-O-benzyl-L-idopyr-
anosyluronate (29)
L
nose 22 (1.3 g, 61%) as syrup Rf 0.3, H) as a mixture of
the two anomers. The H NMR spectrum of this mix-
1
Method (a). To a stirred soln of 26 (1.13 g) and TEMPO
(10 mg) in CH2Cl2 (15 mL) saturated aqueous NaHCO3
(9 mL), KBr (50 mg) and Bu4NBr (75 mg) were added.
The mixture was cooled to 0 °C and a mixture, contain-
ing 0.6 M NaOCl soln (37 mL), satd aq NaHCO3 (5 mL)
and satd NaCl soln (10 mL) was added during a period of
45 min. The organic phase was separated and washed
with water (2 ꢃ 10 mL). The combined aqs solutions were
acidified with 5 N HCl and extracted with CH2Cl2
(3 ꢃ 20 mL). The combined organic solns were dried over
Na2SO4 and concentrated to yield crude 6-carboxylic
acid 28 (0.76 g), which was dissolved in DMF (20 mL)
and stirred in the presence of KHCO3 (1.0 g) and MeI
(0.6 mL) at rt for 16 h. The residue of the concentrated
mixture was dissolved in CH2Cl2, washed with water,
dried and concentrated to yield 29 (0.74 g, 61%) as a
syrup. According to NMR, this was a mixture containing
the a,b-anomers in a ratio of ꢁ1:2. Anal. Calcd for
C20H24O10: C, 56.60; H, 5.70. Found: C, 56.37; H, 5.88.
Method (b). A soln of 27 (0.96 g) in pyridine (7 mL)
and Ac2O (0.5 mL) was kept at rt overnight to give after
usual processing 29 (0.75 g, 71%) as a syrup, which was
identical with that, obtained according method (a).
ture was identical with that, described in lit.19
To a stirred soln of crude 22 (1.3 g, 3.67 mmol) in
CH2Cl2 (25 mL), Et3N (0.7 mL), TBDMSi-Cl (0.66 g,
1.2 equiv) and subsequently DMAP (25 mg) were added
at rt. After 24 h the reaction (Rf 0.3 ! 0.95, H), was not
completed, therefore further TBDMSi-Cl (0.1 g) was
added. After 24 h at rt acetic anhydride (3 mL) and Et3N
(3 mL) was added but no change could be monitored by
TLC (Rf 0.4, D). After 1 h, MeOH (5 mL) was added
and after 30 min the mixture was processed the usual
way to give after concentration of the organic solution
1,2-di-O-acetyl-3-O-benzyl-6-O-tert-butyldimethylsilyl-
L
-idopyranose 23 (1.7 g, ꢁ100%), which according to
NMR was a 1:2 mixture of the a,b-anomers). Anal.
Calcd for C23H36O8Si: C, 58.95; H, 7.74; Si, 5.99.
Found: C, 58.73; H, 7.52; Si, 5.08.
To a stirred soln of an anomeric mixture of crude 23
(1.8 g, 3.85 mmol) in CH2Cl2 (20 mL), pyridine (3 mL)
and subsequently acetyl chloride (1 mL) were added at
0 °C. The mixture was kept at rt for 3 days, then MeOH
(1 mL) was added and after 30 min the mixture was
processed the usual way to give after concentration a
syrup, which was submitted to column chromatography
(D). Concentration of the first fraction afforded 1,2,4-tri-
4.14. Methyl 1,2-di-O-acetyl-3-O-benzyl-L-idopyranosy-
luronate (27)
O-acetyl-3-O-benzyl-6-O-tert-butyldimethylsilyl-a-
L
-ido-
pyranose 24a (120 mg, 6.1%), ½aꢂ ꢀ33 (c 0.7, CHCl3), Rf
D
0.5 (D). Anal. Calcd for C25H38O9Si: C, 58.80; H, 7.50;
Si, 5.50. Found: C, 58.72; H, 7.57; Si, 5.37.
To a stirred soln of 22 (1.42 g) and TEMPO (14 mg) in
CH2Cl2 (20 mL), satd aq NaHCO3 (12 mL), KBr
(66 mg) and Bu4NBr (100 mg) were added. The mixture
was cooled to 0 °C and a mixture, containing a 0.6 M
NaOCl soln (50 mL), satd aq NaHCO3 (6.6 mL) and
satd NaCl soln (13 mL) was added during a period of
45 min. The organic phase was separated and washed
with water (2 ꢃ 15 mL). The combined aq solutions were
acidified with 5 N HCl and extracted with CH2Cl2
(3 ꢃ 25 mL). The dried organic soln was concentrated to
yield crude 6-carboxylate 30 (1.0 g), which was dissolved
in DMF (30 mL) and stirred in the presence of KHCO3
(1.35 g) and MeI (0.8 mL) at rt for 16 h. The residue of
the concentrated mixture was dissolved in CH2Cl2, wa-
shed with water, dried and concentrated to yield 27
(0.96 g, 62%) as a syrup. According to NMR, this was a
mixture containing the a,b-anomers in a ratio of ꢁ1:2.
Anal. Calcd for C18H22O9: C, 56.54; H, 5.80. Found: C,
56.35; H, 6.00.
Concentration of the second fraction gave 24a þ 24b
(550 mg, 28%), while concentration of the third fraction
gave pure 1,2,4-tri-O-acetyl-3-O-benzyl-6-O-t-butyl-
dimethylsilyl-b-
L
-idopyranose 24b (420 mg, 21%), ½aꢂ
D
þ30 (c 1, CHCl3), Rf 0.45 (D). Anal. Calcd for
C25H38O9Si: C, 58.80; H, 7.50; Si, 5.50. Found: C, 58.68;
H, 7.72; Si, 5.39.
4.12. 1,2,6-Tri-O-acetyl- (25) and 1,2,4-tri-O-acetyl-3-O-
benzyl-L-idopyranose (26)
To a soln of the anomeric mixture of the 6-O-silyl
derivative 24a þ 24b (6.5 g, 12.7 mmol) in acetone
(65 mL) 10 N aq sulfuric acid (6 mL) was added at 0 °C.
After 2 h the mixture was neutralised with solid
NaHCO3 (10 g), filtered, concentrated and the residue
submitted to column chromatography using B for elu-
tion. Concentration of the first fraction (Rf 0.4) afforded
25 (0.9 g, 18%), which according to NMR was a 1:2
mixture of the a,b-anomers.
4.15. Methyl(phenyl-2,4-di-O-acetyl-3-O-benzyl-1-thio-a-
L
-idopyranosyl)uronate (31)
Concentration of the second fraction (Rf 0.3) afforded
26 (2.0 g, 40%), which, according to NMR was a 2:3
mixture of the a,b-anomers. Anal. Calcd for C19H24O9:
C, 57.57; H, 6.10. Found: C, 57.33; H, 6.18.
To a stirred soln of an anomeric mixture of 29 (2.12 g,
5.0 mmol) and thiophenol (0.7 mL, 6.8 mmol) in CH2Cl2
(40 mL), BF3ÆEt2O (2 mL) was added at rt. After 2 h the

J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
1577
mixture was poured into 4% aq NaHCO3 solution,
4.19. Phenyl 3-O-benzyl-1-thio-a- -idopyranoside (36a)
L
washed with water, dried and concentrated. The residue
was submitted to column chromatography (C), to yield
31 (1.24 g, 52%), Rf 0.5. Anal. Calcd for C24H26O8S:
C, 60.75; H, 5.52; S, 6.76. Found: C, 60.77; H, 5.77; S,
6.66.
To a soln of 35a (6.4 g) in MeOH (70 mL), 2 M meth-
anolic NaOMe was added and after 2 h at rt the mixture
was neutralised with solid CO2. The residue of the
concentrated mixture was purified by column chroma-
tography (B) to yield 36a (3.4 g, 71.5%), ½aꢂ ꢀ151 (c 1,
D
4.16. 2,5-Anhydro-1,6-di-O-benzoyl-3-O-[methyl (2,4-di-
-manni-
CHCl3), Rf 0.2 (B). Anal. Calcd for C19H22O5S: C,
62.96; H, 6.12; S, 8.85. Found: C, 63.08; H, 6.19; S, 8.72.
O-acetyl-3-O-benzyl-a-
tol (32)
L
-idopyranosyl)uronate]-
D
4.20. Phenyl 3-O-benzyl-4,6-O-benzylidene-1-thio-L-ido-
pyranoside (37)
A soln of 31 (0.94 g, 2.0 mmol) and 6 (0.74 g, 2.0 mmol)
in dry CH2Cl2 (25 mL) was stirred in the presence of
molecular sieve (5 g) for 30 min. Thereafter the mixture
was cooled to ꢀ40 °C and NIS (1.35 g, 6.0 mmol) as well
as TMSOTf (120 lL) were added. The mixture was
stirred at ꢀ40 °C for 20 min, then Et3N (2 mL) was ad-
ded and the temperature was raised to rt. The mixture
was filtered, the filtrate was diluted with CH2Cl2 and
was washed with aq Na2S2O3 and subsequently with a
NaHCO3 soln and water. The dried organic soln was
concentrated and the residue purified by column chro-
matography (B). Concentration of the fractions having
To a soln of 36a (10 g) and p-tolylsulfonic acid (50 mg)
in dry DMF (100 mL) benzaldehyde dimethyl acetal
(10 mL) was added and the mixture was stirred at 70 °C
under diminished pressure (10 kP) for 5 h. The cooled
solution was diluted with ether, washed with water,
dried over Na2SO4 and concentrated. The residue was
submitted to column chromatography (E). Concentra-
tion of the fraction having Rf 0.55 yielded 37a (8 g,
64%), ½aꢂ ꢀ145 (c 1, CHCl3). Anal. Calcd for
D
C26H26O5S: C, 69.31; H, 5.82; S, 7.12. Found: C, 69.22;
H, 5.99; S, 6.89.
When an anomeric mixture of crude 36 was used as
Rf 0.5 gave 32 (0.3 g, 21%); ½aꢂ ꢀ13 (c 1, CHCl3). Anal.
D
Calcd for C38H40O15: C, 61.95; H, 5.47. Found: C, 62.17;
H, 5.59.
starting material, besides 37a (46%) some of the b-
anomer 37b (1 g, 8%) was isolated too; ½aꢂ þ80 (c 1,
D
4.17. 2,4,6-Tri-O-acetyl-3-O-benzyl-a-
bromide (34)
L
-idopyranosyl
CHCl3); Rf 0.4. Anal. Calcd for C26H26O5S: C, 69.31; H,
5.82; S, 7.12. Found: C, 69.14; H, 5.70; S, 6.92.
Under Ar, a soln of TiBr4 (3.1 g, 8.4 mmol) in CH2Cl2
(30 mL) was added to a stirred soln of tetraacetate 33
(2.7 g, 6.2 mmol) in CH2Cl2 (15 mL) and EtOAc
(7.5 mL). The dark brown soln was stirred at rt for 6 h
when according to TLC the reaction was completed (Rf
0.3 ! 0.2, (C). Thereafter toluene (60 mL) and subse-
quently sodium acetate (10 g) were added gradually to
the mixture until its colour turned yellow. The slurry
was filtered, washed with toluene and the filtrate evap-
orated to yield 34 as a pale yellow syrup (2.8 g, 98%), Rf
0.3 (B). No data are given in lit.20
4.21. Phenyl 2-O-acetyl-3-O-benzyl-4,6-O-benzylidene-1-
thio-a- -idopyranoside (38a)
L
(a) A soln of 37a (3.5 g, 7.8 mmol) in pyridine (10 mL)
and Ac2O (5 mL) was kept overnight at rt to give after
usual processing a semisolid residue (3.64 g, 95%), which
was recrystallised from 1.5-fold EtOH to give 38a
(2.5 g). The mother liquor was concentrated and the
residue purified by column chromatography (E) to give
a second crop of 38a (0.6 g). Combined yield 80%. Mp
120–122 °C; Rf 0.4 (E), ½aꢂ ꢀ123 (c 1, CHCl3). Anal.
D
Calcd for C28H28O6S: C, 68.27; H, 5.73; S, 6.51. Found:
C, 68.22; H, 5.79; S, 6.60.
4.18. Phenyl 2,4,6-tri-O-acetyl-3-O-benzyl-1-thio-L-ido-
pyranoside (35)
When 37b was used as starting material, the corre-
sponding b-anomer 38b was obtained as syrup; Rf 0.4
To a stirred soln of crude 33 (40 g, 91 mmol) in CH2Cl2
(500 mL), thiophenol (11 mL, 107 mmol) and BF3ÆEt2O
(31 mL, 245 mmol) were added at 0 °C. Stirring was
continued at rt for 1.5 h, thereafter the mixture was
washed with a 5% NaHCO3 soln and water, dried,
concentrated and the residue (46 g) was submitted to
column chromatography using solvent D for elution.
Concentration of the fraction having Rf 0.5 (C) gave
35a (28 g, 63%); ½aꢂ ꢀ95 (c 1, CHCl3). Lit.19 ½aꢂ ꢀ91 (c
(E), ½aꢂ þ16 (c 1, CHCl3). Anal. Calcd for C28H28O6S:
D
C, 68.27; H, 5.73; S, 6.51. Found: C, 68.11; H, 5.95; S,
6.41.
(b) To a stirred soln of diacetate 21 (13.5 g,
30.5 mmol) and thiophenol (4 mL, 36 mmol) in CH2Cl2
(240 mL) BF3ÆEt2O (10 mL, 79 mmol) was added at
ꢀ20 °C. The mixture was stirred this temperature for
30 min and subsequently at ꢀ10 °C for 45 min. There-
after it was cooled to ꢀ20 °C and Et3N (17 mL) was
added. The mixture was warmed to rt, washed with
water, dried and concentrated. The resulting semisolid
D
D
0.56, CHCl3). The 1H NMR spectrum was identical with
that described in lit.19

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J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
residue was recrystallised from 1.5-fold EtOH to give
38a (5.5 g). The mother liquor was concentrated and the
residue purified by column chromatography (E) to give
a second crop of 38a (2 g). Combined yield 50%. Iden-
tical with that described above.
dissolved in water (10 mL) and extracted with CHCl3 for
removing methyl benzoate. The pH of the aq soln was
adjusted to 8 with M NaOH to give after freeze-drying
the sodium salt 41 (0.7 g, 82.5%), which was filtered with
EtOH. According to NMR investigations this adopts in
Me2SO soln predominantly the 4C1 conformation, ½aꢂ 0
D
4.22. 3-O-(2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-a-
(c 1, water). When TFA was added to the NMR soln, the
1
L
-idopyranosyl)-2,5-anhydro-1,6-di-O-benzoyl-
tol (39)
D
-manni-
liberated free acid was present in the C4 conformation.
The free acid showed a negative optical rotation of ½aꢂ
D
ꢀ12 (c 1, water). Anal. Calcd for C12H19NaO11: C, 39.79;
A soln of thioglycoside 38a (6.2 g, 12.6 mmol) and
2,5-anhydro-1,6-di-O-benzoyl- -mannitol (5.6 g,
H, 5.29; Na, 6.35. Found: C, 39.99; H, 5.38; Na, 6.30.
D
7
15 mmol) in dry CH2Cl2 (180 mL) was stirred in the
presence of molecular sieve (18 g) for 30 min. Thereafter
the mixture was cooled to ꢀ40 °C and NIS (5.6 g,
25 mmol) as well as TfOH (0.35 mL) were added. The
mixture was stirred at ꢀ40 °C for 20 min, then Et3N
(1 mL) was added and the temperature was raised to rt.
The mixture was filtered, the filtrate was diluted with
CH2Cl2 and was washed with aq Na2S2O3 and subse-
quently with NaHCO3 solution and water. The dried
organic solution was concentrated and the residue
purified by column chromatography (D ! C). Concen-
tration of the fractions having Rf 0.3 (C) gave 39 (7.7 g,
4.25. 3-O-(2-O-Acetyl-3,4-di-O-benzoyl-6-O-t-butyltrim-
-idopyranosyl)-2,5-anhydro-1,2,6-tri-O-ben-
zoyl-D-mannitol (43)
ethylsilyl-a-
L
To a stirred soln of 45 (11.4 g, 20.14 mmol) in pyridine
(70 mL) tert-butyldimethylsilyl chloride (3.65 g,
24 mmol) was added at 0 °C. Stirring was continued at
20 °C for 2 h, then further tert-butyldimethylsilyl chlo-
ride (1 g, 6.6 mmol) was added and the mixture was kept
overnight at rt. According to TLC, the starting material
was completely converted into 42 (Rf 0.2 ! 0.7, A).
After cooling the mixture to 0 °C, benzoyl chloride
(8.75 mL, 75.5 mmol) was gradually added (10 min) and
the temperature was raised to rt. After 2 h, the mixture
was poured onto ice, extracted with CH2Cl2 to give after
usual processing and concentration a residue, which was
purified by column chromatography (C). The fractions
having Rf 0.7 afforded on concentration 43 (20 g,
81%) as syrup, ½aꢂ ꢀ28 (c 1, CHCl3). Anal. Calcd for
D
C42H42O13: C, 66.84; H, 5.61. Found: C, 66.61; H, 5.77.
4.23. 2,5-Anhydro-1,4,6-tri-O-benzoyl-3-O-(2-O-acetyl-
3,4-di-O-benzoyl-a-L-idopyranosyluronic acid)-D-manni-
tol (40)
ꢁ100%) as syrup, ½aꢂ ꢀ55 (c 1, CHCl3). Anal. Calcd for
D
To a soln of 44 (13.85 g, 15.65 mmol) in CH2Cl2
(100 mL), TEMPO (50 mg), KBr (260 mg), Bu4NBr
(400 mg) and 4% aq NaHCO3 (100 mL). Thereafter a
mixture of 0.6 M aq NaOCl (180 mL), 4% aq NaHCO3
(25 mL) and brine (50 mL) was added gradually at 0 °C
during 45 min. The mixture was separated, the aq soln
was extracted with CH2Cl2, the combined organic
solutions were washed water, dried over Na2SO4 and
concentrated. The residue was purified by column
chromatography, using first 2:1 EtOAC–hexane for
eluting the faster running by-products and then 5:1
EtOAc–EtOH for eluting the main product (Rf 0.85).
Concentration of this fraction gave 40 (10.65 g, 74.7%)
as solid foam, which was a ꢁ1:3 mixture of the free
C55H58O16Si: C, 65.85; H, 5.83; Si, 2.80. Found: C,
65.61; H, 5.97; Si, 2.62.
4.26. 3-O-(2-O-Acetyl-3,4-di-O-benzoyl-a-
L-idopyrano-
syl)-2,5-anhydro-1,4,6-tri-O-benzoyl- -mannitol (44)
D
To a stirred soln of 43 (20 g, 20.36 mmol) in MeOH
(300 mL) and EtOH (300 mL), M H2SO4 (40 mL) was
added at rt. After 30 min, further M H2SO4 (20 mL) was
added and after 5 h when according to TLC the reaction
was completed (Rf 0.7 ! 0.4, C) solid NaHCO3 was
added gradually until a pH of 5 was obtained. The
mixture was filtered and concentrated. The residue was
dissolved in CH2Cl2, washed with 5% NaHCO3 and
water, dried and concentrated. The residue was purified
by column chromatography (C), to give 44 (17 g, 97%)
carboxylic acid and its sodium salt, ½aꢂ ꢀ40 (c 1,
D
CHCl3). Anal. Calcd for C49H42O17: C, 65.19; H, 4.69.
Found: C, 65.08; H, 4.79.
as syrup, ½aꢂ ꢀ61 (c 1, CHCl3). Anal. Calcd for
D
C49H44O16: C, 66.21; H, 4.99. Found: C, 66.14; H, 5.09.
4.24. Sodium 2,5-anhydro-3-O-(-a-L-idopyranosyluro-
nate)-D-mannitol (41)
4.27. 3-O-(2-O-Acetyl-a-L-idopyranosyl)-2,5-anhydro-
1,6-di-O-benzoyl-D-mannitol (45)
To a soln of 40 (2.25 g, 2.5 mmol) in dry MeOH (50 mL),
2 M NaOMe (1.5 mL, 3 mmol) was added. The mixture
was kept at rt for 30 h, treated with a cation exchange
resin (Hþ), filtered and concentrated. The residue was
A soln of 39 (4.7 g, 6.2 mmol) in MeOH (150 mL) water
(15 mL) and AcOH (0.5 mL) was saturated at rt with
hydrogen using Pd–C (10%, 0.5 g) as catalyst. After 6 h,

J. Kuszmann et al. / Carbohydrate Research 339 (2004) 1569–1579
1579
9. Ahmed, T.; Broder, S.; Whisnant, J. K. U.S. Patent
5,690,910, 1997; Chem. Abstr. 1977, 126, 233706v.
10. Ahmed, T. U.S. Patent 5,980,865, 1999; Chem. Abstr.
1999, 131, 317774g.
11. Ahmed, T.; Smith, G. A. WO Patent 02/083700, 2002;
Chem. Abstr. 2002, 137, 311148h.
€€
12. Jacobsson, I.; Hook, M.; Pettersson, I.; Lindahl, U.;
when according to TLC the reaction was completed (Rf
0.9 ! 0.3, A) the filtered soln was concentrated. Toluene
was added to and evaporated from the residue which,
after recrystallisation from EtOAc–hexane, gave 45
(3.44 g, 95%), mp 142–143 °C, Rf 0.3; ½aꢂ ꢀ13 (c 1,
D
CHCl3). Anal. Calcd for C28H32O13: C, 58.33; H, 5.59.
Found: C, 58.29; H, 5.63.
ꢀ
Larm, O.; Wiren, E.; von Figura, K. Biochem. J. 1979,
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13. Otero, D. A.; Simpson, R. Carbohydr. Res. 1984, 128, 79–86.
14. Lei, Z.; Min, J. M.; Zhang, L. H. Tetrahedron: Asymmetry
2000, 11, 2899–2906.
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