Synthesis of uronic acid-containing xylans found in wood and pulp

Article abstract of DOI:10.1039/b009670a

Two uronic acid-containing trisaccharides, (4-deoxy-β-L-threo-hex-4-enopyranosyluronic acid)- and (4-O-methyl-α-D-gluropyranosyluronic acid)-(1→2)-β-D-xylopyranosyl-(1→4)-D-xylopyranose, found in enzyme hydrolysates from pulp are synthesised. A common dixyloside 2′-OH acceptor, p-methoxyphenyl[3,4-O-(2′,3′-dimethoxybutane-2′,3′- diyl)-β-D-xylopyranosyl]-(1→4)-2,3-di-O-benzoyl-β- D-xylopyranoside, is constructed and coupled with two glucuronate thioglycoside donors differently substituted in the 4-position, O-methyl and O-mesyl, respectively, to give trisaccharides. DMTST as promoter in diethyl ether gives exclusively the α-linked products in high yield. Treatment of the 4″-O-mesyl trisaccharide with DBU then gives the α,β-unsaturated uronic acid derivative. The protection pattern introduced in the acceptor allows continued synthesis of larger oligosaccharides. Removal of the butanedione acetal produces 3′,4′-acceptors, and the p-methoxyphenyl glycoside can be transformed into various glycosyl donors, e.g. thioglycosides and sugar halides. Complete deprotection gives the two target reducing trisaccharides.

Full text of DOI:10.1039/b009670a

View Article Online / Journal Homepage / Table of Contents for this issue
Synthesis of uronic acid-containing xylans found in wood and pulp
Stefan Oscarson* and Pär Svahnberg
Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University,
S-106 91 Stockholm, Sweden
1
Received (in Cambridge, UK) 1st December 2000, Accepted 18th January 2001
First published as an Advance Article on the web 19th February 2001
Two uronic acid-containing trisaccharides, (4-deoxy-β--threo-hex-4-enopyranosyluronic acid)- and (4-O-methyl-
α--gluropyranosyluronic acid)-(1→2)-β--xylopyranosyl-(1→4)--xylopyranose, found in enzyme hydrolysates
from pulp are synthesised. A common dixyloside 2Ј-OH acceptor, p-methoxyphenyl [3,4-O-(2Ј,3Ј-dimethoxybutane-
2Ј,3Ј-diyl)-β--xylopyranosyl]-(1→4)-2,3-di-O-benzoyl-β--xylopyranoside, is constructed and coupled with two
glucuronate thioglycoside donors differently substituted in the 4-position, O-methyl and O-mesyl, respectively, to give
trisaccharides. DMTST as promoter in diethyl ether gives exclusively the α-linked products in high yield. Treatment
of the 4Љ-O-mesyl trisaccharide with DBU then gives the α,β-unsaturated uronic acid derivative. The protection
pattern introduced in the acceptor allows continued synthesis of larger oligosaccharides. Removal of the butanedione
acetal produces 3Ј,4Ј-acceptors, and the p-methoxyphenyl glycoside can be transformed into various glycosyl donors,
e.g. thioglycosides and sugar halides. Complete deprotection gives the two target reducing trisaccharides.
Introduction
Wood consists mainly of cellulose, lignin and hemicellulose.
The several different hemicelluloses found in wood are all small
heteropolymers that comprise several hundred monosaccharide
units. The amount of hemicellulose in wood is usually between
20 and 30% of the dry weight. The most common hemicellulose
in hardwood is a glucuronoxylan. The backbone structure
consists of β-(1→4)-linked D-xylopyranose units, about 70%
of which have an O-acetyl group at either position 2 or 3. In
addition, at about every tenth xylose unit there is an α-(1→2)-
linked 4-O-methylglucuronic acid (MeGlcA) residue.1 The
alkaline conditions used during kraft pulping of the wood
cleave the acetate groups of glucuronoxylan. In addition, the
MeGlcA side groups are partly converted into hexenuronic acid
(HexA) via β-elimination and into 4-O-methyl--iduronic acid
via C-5 epimerisation. Partial enzyme hydrolysis of the kraft
pulp generates an array of oligosaccharides with different
length, preferably with the uronic acid substituent at the non-
reducing end.2–4 To aid in the characterisation of such complex
mixtures synthetic oligosaccharide model compounds are use-
ful. Syntheses of the 4-O-methylglucuronic acid residue5 as well
as the 4-O-Me-α--GlcA-(1→2)-β--Xyl disaccharide6 have
been published. In this article the syntheses of the MeGlcA-
and HexA-containing trisaccharides 17 and 21 are described.
The synthetic pathway chosen allows continued synthesis of
larger fragments of the glucuronoxylan.
Scheme 1
Results and discussion
Since the target trisaccharides contain a common dixyloside
remove to give the target reducing trisaccharides, but also
motif, it was decided to first construct this as a common
should preferably directly function as a donor leaving group or
acceptor derivative (7, Scheme 1) and then introduce the uronic
be easily transformed into one to allow the production of larger
acid residues. As glycosyl donors thioglycosides were selected,
xylan fragments. The trimethylsilylethyl group, thoroughly
because of our good experiences with such donors, but the
investigated by G. Magnusson and co-workers,7 was considered
choice of anomeric protecting group to be introduced at the
as well as an allyl group. Finally, a p-methoxyphenyl (PMP)
reducing end of the acceptor was not obvious. Other things to
glycoside was chosen, which, besides being stable under most
consider were when to introduce the carboxy function and the
coupling and protecting-group-manipulation conditions, is
unsaturation.
easily hydrolysed to give the hemiacetal, and, furthermore, effi-
ciently can be transformed into halide sugars or thioglycosides,
Preparation of the dixyloside acceptor
as recently reported by Zhang and Magnusson.8 Accordingly,
The aglycone part in the acceptor xyloside should be easy to
DOI: 10.1039/b009670a
the known9 acetylated p-methoxyphenyl xyloside
1
was
J. Chem. Soc., Perkin Trans. 1, 2001, 873–879
873
This journal is © The Royal Society of Chemistry 2001

View Article Online
prepared and deacetylated. The selective protection of hydroxy
groups in xyloside derivatives is not trivial since all hydroxy
groups are secondary, equatorial, and trans. However, using
stannylene activation a reactivity difference between the three
hydroxy groups in a β-xyloside has been observed and the
reactivity is known to be OH-4 > OH-3 > OH-2.10 Thus, sub-
sequent stannylene activation and monochloroacetylation gave
the 4-O-protected derivative 2 (47%) (Scheme 1). Benzoylation
followed by selective removal of the chloroacetyl group by
hydrazine acetate treatment then yielded the acceptor 3 (62%).
As precursor for the donor, ethyl thioxyloside11 4 was selected.
Treatment of 4 with butanedione and camphor-10-sulfonic acid
(CSA) in the presence of trimethyl orthoformate gave the 3,4-
O-(2Ј,3Ј-dimethoxybutane-2Ј,3Ј-diyl) ketal (BDA)12–14 together
with the 2,3-regioisomer, which could easily be separated on a
silica gel column. Chloroacetylation of the 3,4-isomer then gave
donor 5 (55% overall yield from 4). An analogue to donor 5
with a 4-O-tert-butyldimethylsilyl (TBDMS) and a 3-O-acetyl
group was first prepared and used in couplings to 3 to give a
dixyloside.15 However, when the chloroacetyl goup was
removed and the resulting 2Ј-OH compound was tried as
acceptor in couplings with glucuronate donors 11 and 13 no
trisaccharides at all were obtained. One explanation for the low
reactivity of the 2Ј-hydroxy group could be the deactivating
effect of the 3Ј-O-acetyl group, and consequently another pro-
tection pattern was introduced. Coupling between acceptor
3 and donor 5 promoted by N-iodosuccinimide–trifluoro-
methanesulfonic acid (NIS–TfOH) efficiently gave disaccharide
6 (83%), dechloroacetylation of which gave the dixyloside
acceptor 7 (71%) (Scheme 1).
Scheme 2
Trisaccharide synthesis
As had been shown earlier,22,23 glucuronate thioglycosides
proved effective as donors to produce trisaccharides. Primary
model couplings with the 4-O-benzoyl-protected donor
afforded insight into the stereospecific outcome of the reaction,
which proved to be very sensitive to changes in the reaction
conditions (Scheme 3). Coupling with 7 using dimethyl(methyl-
Preparation of the glucuronate donors
Since the native glucuronic acid is α-linked a non-participating
protecting group in the 2-position was necessary. A benzyl
group was chosen, which more or less excluded glucuronic acid
precursors, since these are difficult to benzylate in good yields.
Instead, glucose derivative 816 was selected as starting material
and regioselectively tritylated to give 9 (93%) (Scheme 2). Com-
pound 9 was either methylated or mesylated and the trityl
group then removed to yield the primary alcohol derivatives 10
(67%) and 12 (68%), respectively. In spite of the large number
of oxidation methods available the oxidation of these alcohols
to a uronic acid derivative is still not trivial. Often an optimis-
ation has to be performed for each specific compound to find
optimum reagents and conditions, and the yield is seldom excel-
lent or even very high, which makes it an advantage to perform
the oxidation early in the synthesis. The use of thioglycosides
brings in an additional possible complication, i.e. oxidation
of sulfur, but the use of dimethyl sulfoxide (DMSO)-based
oxidation methods usually circumvents this problem. Swern
oxidation17 of 10 followed by pyridinium dichromate (PDC)-
oxidation of the intermediate aldehyde in the presence of
MeOH18 gave the methyl ester glucuronate 11 (57%). Swern
oxidation of 12, however, gave mainly the 4,5-unsaturated alde-
hyde, which proved impossible to oxidise further with PDC.
Instead, a Pfitzner–Moffat oxidation19,20 was tried, to produce
the saturated aldehyde, which was then oxidised to the methyl
ester derivative 13 (49%) by PDC–MeOH. Originally, com-
pound 13 was designed as the 4-O-benzoyl derivative,15 since an
elimination reaction of this using 1,7-diazabicyclo[5.4.0]undec-
7-ene (DBU) as base proceeded smoothly at the monosacchar-
ide stage to give the 4,5-unsaturated glucuronic acid as has also
been shown by others (Scheme 3).21 However, at the trisacchar-
ide level it proved impossible to eliminate the benzoate
irrespective of the base used.15 Also, the corresponding galacto
analogue proved inert in spite of the supposed more favourable
trans-diaxial arrangement of the groups to be eliminated. In
addition a tosyl group was tried as leaving group, but the mesyl
group was found to be the best alternative.
Scheme 3
thio)sulfonium triflate (DMTST) as promoter in diethyl ether,
conditions known to promote α-glycosylation,24 yielded 76% of
the α-linked trisaccharide 14ꢀ (δC 96.3, C-1Љ), whereas NIS as
promoter in CH2Cl2 gave 62% of the β-product 14ꢁ (δC 102.5 or
102.8, C-1Љ). Thus, good conditions for obtaining the desired
α-glycoside were found and these were shown to be general for
the other donors as well. Coupling of acceptor 7 with donor 11
with DMTST as promoter gave trisaccharide 15 (δC 97.1, C-1Љ)
in 89% yield, and coupling with donor 13 gave trisaccharide 18
(δC 95.9, C-1Љ) in 80% yield (Schemes 4 and 5).
To obtain the unsaturated derivative, trisaccharide 18 was
first subjected to catalytic hydrogenolysis to remove the benzyl
groups (which removal in the presence of a double bond might
have caused problems) and then treated with DBU to accom-
plish the elimination (→19, 72%). Efforts were also made to
produce an unsaturated trisaccharide derivative by using an
unsaturated glucuronate thioglycoside donor, (as mentioned
above) easily obtained by DBU treatment of derivative 13 or its
4-O-benzoyl analogue (Scheme 3). This donor, however, turned
out to be inert to activation by any thiophilic promoter. Even
under rather harsh conditions (DMTST ϩ NIS, TfOH, reflux
CH2Cl2) the unsaturated glucuronate thioglycoside was stable.
874
J. Chem. Soc., Perkin Trans. 1, 2001, 873–879

View Article Online
configuration of the glucuronic acid residues could be verified
by 1H NMR [δH(acetone-d6) 5.28 (1 H, d, J1,2 3.8 Hz, H-1MeGlcA
)
and δH(CDCl3–MeOH) 5.36 (1 H, d, J1,2 2.2 Hz, H-1HexA]. How-
ever, when removal of the PMP group in these compounds was
attempted, hydrolysis of the linkage between the two xylose
residues was observed, probably due to the acidity of the
reagent, cerium() ammonium nitrate (CAN) in CH3CN–
water. For stabilisation and to make the products organic-
soluble, the tetraols obtained after removal of the benzyl
groups and/or BDA ketals from 15 and 19 were therefore first
acetylated to give compounds 16 and 20. Removal of the PMP
group from these derivatives now proceeded in good to excel-
lent yields (64 and 99%, respectively, the HexA trisaccharide
isolated as its anomeric acetate) without any detected hydrolysis
of the resulting trisaccharides. Finally, deacylation under
Zemplén conditions and saponification of the methyl ester gave
the target compounds 17 and 21, whose NMR data were in
excellent agreement with those recorded for similar structures
obtained through enzymatic degradation of pulp.4
Conclusions
Scheme 4
The syntheses of two uronic acid-containing trisaccharide
structures found in hemicellulose pulp have been completed.
Features of the syntheses are: Use of a BDA ketal to temporar-
ily protect the 3- and 4-hydroxy groups in a xylose residue
without lowering the reactivity of the 2-OH group; Use of
glucuronate thioglycoside donors with a 2-O-nonparticipating
group, with which the stereoselectivity in glycosylations can be
controlled by the conditions employed. DMTST in diethyl
ether gave α-glycosides, whereas NIS in CH2Cl2 yielded
β-glycosides; Use of PMP glycosides, which can be either
hydrolysed to obtain the target reducing saccharides or
converted to a donor for continued synthesis.
In the preparation of the unsaturated structure it was experi-
enced that the usually easy β-elimination reaction required a
very good leaving group when performed at the trisaccharide
stage. It was also found that a 4-deoxyhex-4-enuronate thio-
glycoside donor was inert towards activation even with strong
thiophilic promoters.
Experimental
General
TLC was carried out on Merck precoated 60 F254 plates using
UV light and/or 8% sulfuric acid for visualisation. Column
chromatography was performed on silica gel (0.040–0.063 mm,
Amicon). NMR spectra were recorded in CDCl3 (internal
Me4Si, δ = 0.00) or D2O (internal acetone; δC = 31.0, δH = 2.21)
at 25 ЊC on a Varian 300 MHz or 400 MHz instrument. Opti-
mal rotations were measured on a Perkin-Elmer 241 polar-
imeter; [α]D-values are given in units of 10Ϫ1 deg cm2 gϪ1.
Organic phases were dried over Na2SO4 before evaporation,
which was performed under reduced pressure.
Scheme 5
This inertness may be due to an inductive effect and/or a tor-
sional ‘disarming’ effect in the formation of the intermediate
oxocarbenium ion, as has been suggested for 4,6-O-benzylidene
donors,25 and will have to be investigated.
p-Methoxyphenyl 2,3-di-O-benzoyl-ꢁ-D-xylopyranoside 3
The two derivatives 15 and 19 are both designed to allow
their transformation into new acceptors and donors for con-
tinued syntheses of larger glucuronoxylan fragments. After
debenzylation (of 15) and acetylation, removal of the BDA
ketal will give 3Љ,4Љ-diol acceptors, whereas conversion of
the PMP glycoside into halide sugars, trichloroimidates or
thioglycosides will produce trisaccharide donors.8
A solution of 19 (13 g, 34.4 mmol) in MeOH (250 ml) was
treated with a catalytic amount of 1 M methanolic NaOMe at
room temperature overnight. Dowex 50 (Hϩ) ion-exchange
resin was added until neutral pH and the mixture was then
filtered and concentrated. The deacetylated material and
dibutyltin oxide (9.0 g, 36.1 mmol) were suspended in toluene
(500 ml) and the mixture was refluxed overnight in a flask
equipped with a Dean–Stark trap. The resulting clear solution
was cooled to Ϫ40 ЊC under Ar and chloroacetyl chloride (3 ml,
37.8 mmol) was added dropwise. After the addition was
complete, the reaction mixture was allowed to attain room
temperature (4 h). The crude mixture was concentrated, the
residue was dissolved in MeCN, and the solution was washed
Deprotection
Removal of all the protecting groups except the methyl ester
and the p-methoxyphenyl group from compounds 15 and 19
proceeded smoothly to give compounds in which the assumed
(from 13C-shift of the anomeric signals in 15 and 18) anomeric
J. Chem. Soc., Perkin Trans. 1, 2001, 873–879
875

View Article Online
twice with light petroleum (40–65 ЊC). Evaporation of the sol-
vent followed by silica gel chromatography (toluene–EtOAc
1 : 3) afforded p-methoxyphenyl 4-O-chloroacetyl-β--xylo-
pyranoside 2 (5.3 g, 47%) as a white solid, δC(CDCl3) 40.7
(ClCH2CO), 55.8 (OMe), 61.4 (C-5), 72.1, 72.3 and 72.7
(C-2–4), 101.7 (C-1).
yielded 7 (2.65 g, 71%) (Found: C, 62.35; H, 6.09. Calc. for
C37H42O14: C, 62.53; H, 5.96%); δC(CDCl3) 17.5 and 17.6
(BDA), 47.8 and 47.9 (BDA), 55.6 (OMe), 62.3, 63.9, 65.5, 70.3,
70.9, 71.4, 72.2 and 75.0 (C-2–5, 2Ј–5Ј), 99.4, 99.5, 99.7 and
104.1 (C-1, -1Ј, BDA), 114.6–155.4 (Ph), 165.3 and 165.5
(PhCO); δH(CDCl3) 4.37 (1 H, d, J1,2 6.6 Hz, H-1Ј), 5.30 (1 H,
d, J1,2 5.5 Hz, H-1).
Benzoyl chloride (318 µl, 2.74 mmol) was added to a solution
of 2 (225 mg, 0.69 mmol) in CH2Cl2–pyridine (15 : 1; 16 ml) at
0 ЊC. After being stirred overnight at room temperature the
mixture was washed successively with water, 1 M HCl and
saturated aq. NaHCO3, dried, filtered and concentrated. Purifi-
cation of the residue by silica gel chromatography (toluene–
EtOAc 6 : 1) gave the dibenzoylated material, which was
dissolved in MeOH (15 ml), and hydrazine acetate (59 mg, 0.64
mmol) was added. After 6 h at room temperature the reaction
mixture was concentrated, and purified by silica gel chrom-
atography (toluene–EtOAc 3 : 1) to give 3 (203 mg, 62%); [α]D
ϩ70 (c 0.1 in CHCl3) (Found: C, 67.05; H, 5.21. Calc. for
C26H24O8: C, 67.23; H, 5.21%); δC(CDCl3) 55.6 (OMe), 64.6,
68.4, 70.4 and 75.2 (C-2–5), 99.9 (C-1), 114.6–155.5 (Ph), 165.2
and 167.0 (PhCO).
Methyl (ethyl 2,3-di-O-benzyl-4-O-methyl-1-thio-ꢁ-D-gluco-
pyranosid)uronate 11
Chlorotriphenylmethane (2.27 g, 8.14 mmol) was added to a
solution of 816 (3.00 g, 7.42 mmol) in pyridine (16 ml) at room
temperature. After being stirred overnight at 55 ЊC the mixture
was diluted with toluene and concentrated. Co-evaporation
twice from toluene gave a crude product, which was purified
by silica gel chromatography (toluene–EtOAc 19 : 1) to yield
ethyl 2,3-di-O-benzyl-6-O-triphenylmethyl-1-thio-β--gluco-
pyranoside 9 (4.46 g, 93%); δC(CDCl3) 15.2 (SEt), 24.7 (SEt),
64.4 (C-6), 72.2, 75.4, 75.5, 78.0, 81.3, 84.7, 86.1 and 87.0 (C-1–
5, Ph3C, PhCH2), 126.7–143.7 (Ph).
Sodium hydride (60% dispersion in oil; 92 mg, 2.32 mmol)
was washed with dry light petroleum (40–65 ЊC). DMF (5 ml)
was added and subsequently a solution of 9 (1.0 g, 1.55 mmol)
in DMF (10 ml) dropwise at 0 ЊC. After 1 h, a solution of
methyl iodide (135 µl, 2.16 mmol) in DMF (3 ml) was added
and the solution was allowed to attain room temperature. After
3 h, MeOH (1 ml) was carefully added and the mixture was
diluted with toluene, washed three times with water, dried, and
concentrated in vacuo. The residue was dissolved in CHCl3–
MeOH (2 : 1; 75 ml) and the pH was adjusted to 2 by addition
of toluene-p-sulfonic acid (PTSA). After 2 h, the mixture was
washed successively with water and saturated aq. NaHCO3,
dried, concentrated, and purified on a silica gel column
(toluene–EtOAc 6 : 1) to give ethyl 2,3-di-O-benzyl-4-O-methyl-
1-thio-β--glucopyranoside 10 (435 mg, 67%); δC(CDCl3) 15.1
(SEt), 25.2 (SEt), 60.8, 62.1 (OMe, C-6), 75.6, 75.7, 79.3, 79.9,
81.6, 85.2 and 86.3 (C-1–5. PhCH2), 127.7–138.5 (Ph).
A stirred solution of oxalyl dichloride (348 µl, 4.06 mmol) in
CH2Cl2 (5 ml) in a 50 ml round-bottomed flask equipped with a
pressure-equalising dropping funnel was cooled to Ϫ60 ЊC. A
mixture of DMSO (655 µl, 9.23 mmol) in CH2Cl2 (5 ml) was
added dropwise to the stirred oxalyl dichloride solution, fol-
lowed by dropwise addition of a solution of 10 (1.54 g, 3.69
mmol) in CH2Cl2 (10 ml). Stirring was continued for 15 min,
NEt3 (1.69 ml, 12.18 mmol) was added and the reaction mixture
was stirred for 5 min more at Ϫ60 ЊC and then allowed to attain
room temperature. 1 M HCl (30 ml) was added, the phases were
separated, and the aqueous layer was reextracted with CH2Cl2
(30 ml). The combined organic layers were washed with satur-
ated aq. NaCl (50 ml), dried and concentrated. The crude alde-
hyde was dissolved in dry DMF (40 ml) containing MeOH (0.9
ml, 22.1 mmol) and the solution was cooled on ice for 30 min in
a vessel covered to exclude light. PDC (8.3 g, 22.1 mmol) was
added in one portion. The mixture was allowed to attain room
temperature and react overnight and was then poured into a
beaker containing EtOAc in order to precipitate chromium
salts. The mixture was filtered through Celite, concentrated,
and purified on a silica gel column (toluene–EtOAc 12 : 1) to
give 11 (934 mg, 57%), mp 67–68 ЊC; [α]D ϩ4 (c 1 in CHCl3)
(Found: C, 64.55; H, 6.75. Calc. for C24H30O6S: C, 64.55; H,
6.77%); δC(CDCl3) 14.9 (SEt), 25.1 (SEt), 52.4 (6-OMe), 60.6
(4-OMe), 75.4, 75.6, 77.8, 80.8, 81.0, 85.5 and 85.7 (C-1–5,
PhCH2), 127.5–138.1 (Ph), 168.5 (C-6).
Ethyl 2-O-chloroacetyl-3,4-O-(2Ј,3Ј-dimethoxybutane-2Ј,3Ј-
diyl)-1-thio-ꢁ-D-xylopyranoside 5
CSA (420 mg, 1.8 mmol) was added to a solution of 412 (3.5 g,
18 mmol), butanedione (1.74 ml, 19.8 mmol), and trimethyl
orthoformate (5.93 ml, 54 mmol) in dry MeOH (100 ml). The
mixture was refluxed for 2 h and then neutralised with NEt3 (0.5
ml), concentrated, and purified by silica gel chromatography
(toluene–EtOAc 3 : 1) to give the 3,4-BDA derivative (3.3 g,
59%) and 1.9 g (34%) of the 2,3-BDA isomer.
Chloroacetyl chloride (179 µl, 2.24 mmol) was added to a
solution of the 3,4-BDA derivative (393 mg, 1.12 mmol) in
CH2Cl2–pyridine (15 : 1; 16 ml) at 0 ЊC. The reaction mixture
was stirred for 3 h at room temperature, then diluted with tolu-
ene, concentrated, and purified by silica gel chromatography
(toluene–EtOAc 9 : 1) to afford 5 (381 mg, 92%); [α]D ϩ110 (c 1
in CHCl3) (Found: C, 46.69; H, 6.59. Calc. for C15H25ClO7S: C,
46.81; H, 6.55%); δC(CDCl3) 14.8 (SEt), 17.5 and 17.6 (BDA),
23.6 (SEt), 40.7 (ClCH2CO), 47.8 and 48.0 (BDA), 65.9, 67.8,
70.7 and 71.9 (C-2–5), 84.2 (C-1), 99.6 and 100.0 (BDA), 165.9
(ClCH2CO).
p-Methoxyphenyl [3,4-O-(2Ј,3Ј-dimethoxybutane-2Ј,3Ј-diyl)-ꢁ-
D-xylopyranosyl]-(1→4)-2,3-di-O-benzoyl-ꢁ-D-xylopyranoside 7
A mixture of 3 (3.00 g, 6.52 mmol) and 5 (3.61 g, 9.77 mmol)
in dry CH2Cl2 (150 ml) containing powdered molecular sieves
(4 Å) was stirred under Ar at room temperature for 30 min. The
solution was then cooled to 0 ЊC, NIS (2.20 g, 9.77 mmol) and
triflic acid (288 µl, 3.2 mmol) were added, and the mixture was
stirred for 1 h. The reaction was quenched with the addition of
NEt3 (0.5 ml). The mixture was stirred for 10 min and then
filtered through Celite. The filtrate was washed successively with
Na2S2O3 (10% aq.), NaHCO3 (saturated aq.) and water, dried
and concentrated. The residue was purified by silica gel chro-
matography (toluene–EtOAc 6 : 1) to yield p-methoxyphenyl [2-
O-chloroacetyl-3,4-O-(2Ј,3Ј-dimethoxybutane-2Ј,3Ј-diyl)-β--
xylopyranosyl]-(1→4)-2,3-di-O-benzoyl-β--xylopyranoside 6
(4.25 g, 83%). δC(CDCl3) 17.4 and 17.6 (BDA), 40.5 (ClCH2-
CO), 47.7 and 47.9 (BDA), 55.6 (OMe), 62.3, 63.8, 65.3, 70.2,
70.3, 71.4, 72.7 and 75.8 (C-2–5, 2Ј–5Ј), 99.5, 99.6, 99.7 and
102.4 (C-1, -1Ј, BDA), 114.6–155.5 (Ph), 165.2, 165.3 and 165.5
(PhCO, ClCH2CO).
Hydrazine acetate (724 mg, 7.87 mmol) was added to a solu-
tion of 6 (4.13 g, 5.25 mmol) in MeOH (100 ml) and the mixture
was stirred overnight. Additional hydrazine acetate (200 mg,
2.17 mmol) was added and after 2 h the solution was diluted
with CHCl3, washed with water, dried and concentrated. Silica
gel chromatography (toluene–EtOAc 3 : 1) of the residue
Methyl (ethyl 2,3-di-O-benzyl-4-O-methylsulfonyl-1-thio-ꢁ-D-
glucopyranosid)uronate 13
NEt3 (1.47 ml, 10.5 mmol) and methanesulfonyl chloride (818
µl, 10.5 mmol) were added to a solution of 9 (2.27 g, 3.5 mmol)
in EtOAc (50 ml) at 0 ЊC. The mixture was stirred for 1 h, then
876
J. Chem. Soc., Perkin Trans. 1, 2001, 873–879

View Article Online
diluted with EtOAc (50 ml), washed successively with water and
1 M HCl, dried and concentrated. The residue was dissolved in
CHCl3–MeOH (2 : 1; 75 ml) and the pH was adjusted to 2 by
addition of PTSA. After 2 h, the mixture was washed succes-
sively with water and saturated aq. NaHCO3 (aq, sat), dried,
concentrated and purified on a silica gel column (toluene–
EtOAc 2 : 1) to give ethyl 2,3-di-O-benzyl-4-O-methylsulfonyl-
1-thio-β--glucopyranoside 12 (1.15 g, 68%); δC(CDCl3) 15.0
(SEt), 25.2 (SEt), 38.3 (OMs), 61.0 (C-6), 75.4, 75.6, 78.1, 81.8,
83.1 and 85.1 (C-1–5, PhCH2), 127.4–137.1 (Ph).
mg, 2.48 mmol) and the stirring was continued for 1.5 h. After
neutralisation with NEt3 (0.5 ml), the mixture was filtered
through Celite and concentrated. The residue was purified on a
silica gel column (toluene–EtOAc 6 : 1) to yield the 14ꢀ (560 mg,
76%); δC(CDCl3) 17.2 and 17.5 (BDA), 47.7 and 47.8 (BDA),
52.3 (6Љ-OMe), 55.6 (PMP-OMe), 61.5, 63.4, 65.5, 68.4, 69.9,
70.6, 70.9, 72.0, 73.3, 73.7, 74.1, 75.0, 77.9 and 78.7 (C-2–5, -2Ј–
5Ј, -2Љ–5Љ, PhCH2), 96.3, 99.0, 99.2, 99.8 and 103.0 (C-1, 1Ј, 1Љ,
BDA), 114.3–155.2 (Ph), 164.9 and 165.0 (PhCO), 169.0 (C-6Љ).
Pyridine (192 µl, 2.38 mmol), CF3COOH (89 µl, 1.19 mmol)
and dicyclohexylcarbodiimide (DCC) (1.72 g, 8.35 mmol) were
added to a solution of 12 (1.15 g, 2.38 mmol) in DMSO (30 ml)
at room temperature. The mixture was stirred overnight. Oxalic
acid (1 g) dissolved in MeOH (25 ml) was added to the reaction
mixture in order to precipitate formed N,N-dicyclohexylurea,
and after 30 min the mixture was filtered. Toluene and saturated
aq. NaCl were added to the filtrate and the phases were separ-
ated. The organic phase was washed successively with water,
saturated aq. NaHCO3 and water. After drying and concen-
tration of the organic phase, the obtained crude aldehyde
was dried on a pump and used for the next oxidation without
further purification. The crude aldehyde was dissolved in dry
DMF (25 ml) containing MeOH (0.55 ml, 14.28 mmol) and the
solution was cooled on ice for 30 min in a vessel covered to
exclude light. PDC (5.4 g, 14.28 mmol) was added in one por-
tion. The mixture was allowed to attain room temperature and
react overnight and then poured into a beaker containing
EtOAc in order to precipitate chromium salts. The mixture was
filtered through Celite and the solvents were evaporated. Fur-
ther purification was accomplished through silica gel chrom-
atography (toluene–EtOAc 10 : 1) and recrystallisation to give
13 (526 mg, 49%), mp 82–83 ЊC (from EtOAc–hexane); [α]D ϩ3
(c 1 in CHCl3) (Found: C, 55.60; H, 5.98. Calc. for C24H30O8S2:
C, 56.45; H, 5.92%); δC(CDCl3) 14.9 (SEt), 25.0 (SEt), 38.5
(OMs), 52.7 (6-OMe), 75.2, 75.5, 76.5, 77.7, 81.0, 82.5 and 85.2
(C-1–5, PhCH2), 127.5–137.2 (Ph), 166.8 (C-6).
p-Methoxyphenyl (methyl 2,3-di-O-benzyl-4-O-methyl-ꢀ-D-
glucopyranosyluronate)-(1→2)-[3,4-O-(2Ј,3Ј-dimethoxybutane-
2Ј,3Ј-diyl)-ꢁ-D-xylopyranosyl]-(1→4)-2,3-di-O-benzoyl-ꢁ-D-
xylopyranoside 15
A solution of 7 (120 mg, 0.28 mmol) and 11 (114 mg, 0.42
mmol) in dry diethyl ether (10 ml) containing powdered
molecular sieves (4 Å) was stirred at 0 ЊC in an Ar atmosphere
for 30 min. To the mixture was added DMTST (174 mg, 1.12
mmol) and stirring was continued for 6 h. After neutralisation
with NEt3 (0.5 ml), the mixture was filtered through Celite and
concentrated. The residue was purified on a silica gel column
(toluene–EtOAc 6 : 1) to yield 15 (165 mg, 89%); [α]D ϩ61 (c 0.7
in CHCl3) (Found: C, 64.55; H, 6.16. Calc. for C59H66O20: C,
64.71; H, 6.07); δC(CDCl3) 17.8 and 17.9 (BDA), 48.1 and 48.5
(BDA), 52.5 (6Љ-OMe), 56.0 (PMP-OMe), 61.0, 61.8, 63.8, 65.0,
70.3, 70.4, 71.1, 71.2, 73.5, 74.0, 74.8, 75.7, 79.2, 81.4 and 82.8
(4Љ-OMe, C-2–5, -2Ј–5Ј, -2Љ–5Љ, PhCH2), 97.1, 99.4, 99.7, 100.2
and 103.4 (C-1, 1Ј, 1Љ, BDA), 114.7–155.5 (Ph), 165.2 and 165.3
(PhCO), 171.1 (C-6Љ).
(4-O-Methyl-ꢀ-D-glucopyranosyluronic acid)-(1→2)-D-xylo-
pyranosyl-(1→4)-D-xylopyranose 17
To a solution of 15 (72 mg, 0.07 mmol) in EtOAc–MeOH–
water–HOAc 4 : 4 : 1 : 1 (5 ml) was added Pd(OH)2 on activated
carbon powder and the mixture was hydrogenolyzed at 100 psi
for 24 h. The mixture was then filtered through Celite and the
filter washed with CH2Cl2 (50 ml). The filtrate was concen-
trated to 5 ml, diluted with EtOAc (20 ml), washed successively
with water and saturated aq. NaHCO3, dried and concentrated.
The residue was dissolved in CH3CN (1 ml) and cooled in
ice. CF3COOH (aq. 95%; 2 ml) was added and the mixture
was stirred for 1 h, then diluted with toluene and concen-
trated to give the crude tetraol. This was stirred overnight
at room temperature in acetic anhydride–pyridine (1 : 1; 5 ml).
The mixture was diluted with toluene and concentrated.
Co-evaporation of the residue twice from toluene followed
by silica gel chromatography (toluene–EtOAc 1 : 1) gave
p-methoxyphenyl (methyl 2,3-di-O-acetyl-4-O-methyl-α--
glucopyranosyluronate)-(1→2)-(3,4-di-O-acetyl-β--xylopyran-
osyl)-(1→4)-2,3-di-O-benzoyl-β--xylopyranoside 16 (64 mg,
80%); δC(CDCl3) 20.6, 20.7 and 20.8 (MeCO), 52.5 (6Љ-OMe),
55.5 (PMP-OMe), 60.1, 60.1, 62.3, 69.2, 69.3, 69.8, 69.9, 70.2,
71.2, 72.1, 73.2, 74.2 and 78.8 (4Љ-OMe, C-2–5, -2Ј–5Ј, -2Љ–5Љ),
95.5, 98.0 and 101.7 (C-1, -1Ј, -1Љ), 114.4–155.0 (Ph), 164.8 and
165.0 (PhCO), 169.0, 169.3, 169.6 and 169.9 (MeCO and C-6Љ).
CAN (65 mg, 0.12 mmol) was added at 0 ЊC to a solution of
16 (64 mg, 0.06 mmol) in CH3CN–water (2 : 1; 6 ml). The mix-
ture was stirred for 10 min, then diluted with EtOAc (20 ml)
and washed successively with water and brine. The organic
phase was dried and concentrated. Silica gel chromatography
(toluene–EtOAc 1 : 1) afforded the hemiacetal (35 mg, 61%);
δC(CDCl3) 21.0, 21.2 and 21.3 (MeCO), 53.0 (6Љ-OMe), 59.7,
60.5, 62.6, 69.5, 70.5, 70.6, 71.3, 71.4, 72.5, 72.9, 75.4, 76.0, 77.5
and 79.4 (4Љ-OMe, C-2–5, -2Ј–5Ј, -2Љ–5Љ), 90.8, 96.9 and 101.5
(C-1, -1Ј, -1Љ), 128.5–133.5 (Ph), 165.8 and 166.0 (PhCO), 169.5,
170.1, 170.2 and 170.7 (MeCO and C-6Љ).
p-Methoxyphenyl (methyl 4-O-benzoyl-2,3-di-O-benzyl-ꢁ-D-
glucopyranosyluronate)-(1→2)-[3,4-O-(2Ј,3Ј-dimethoxybutane-
2Ј,3Ј-diyl)-ꢁ-D-xylopyranosyl]-(1→4)-2,3-di-O-benzoyl-ꢁ-D-
xylopyranoside 14ꢁ
A mixture of methyl (ethyl 4-O-benzoyl-2,3-di-O-benzyl-1-
thio-β--glucopyranosid)uronate (100 mg, 0.19 mmol) and 7
(89 mg, 0.12 mmol) in dry CH2Cl2 (10 ml) containing powdered
molecular sieves (4 Å) was stirred under Ar at room tempera-
ture for 30 min. The solution was cooled to 0 ЊC, NIS (42 mg,
0.19 mmol) and triflic acid (5.5 µl, 0.06 mmol) were added, and
the mixture was stirred at room temperature overnight. The
reaction mixture was quenched with the addition of NEt3 (0.1
ml), stirred for 10 min, and filtered through Celite. The filtrate
was washed successively with 10% aq. Na2S2O3, saturated aq.
NaHCO3, and water, dried and evaporated. The residue was
purified by silica gel chromatography (toluene–EtOAc 9 : 1) to
yield 14ꢁ (92 mg, 62%); δC(CDCl3) 17.5 and 17.7 (BDA), 47.8
and 47.9 (BDA), 52.5 (6Љ-OMe), 55.5 (PMP-OMe), 62.0, 63.5,
65.1, 70.3, 71.7, 72.7, 73.9, 74.9, 75.1, 78.1, 81.4 and 82.0 (C-2–
5, -2Ј–5Ј, -2Љ–5Љ, PhCH2), 99.1, 99.4, 99.5, 102.5 and 102.8 (C-1,
-1Ј, -1Љ, BDA), 114.3–155.1 (Ph), 165.0 (PhCO), 167.7 (C-6Љ).
p-Methoxyphenyl (methyl 4-O-benzoyl-2,3-di-O-benzyl-ꢀ-D-
glucopyranosyluronate)-(1→2)-[3,4-O-(2Ј,3Ј-dimethoxybutane-
2Ј,3Ј-diyl)-ꢁ-D-xylopyranosyl]-(1→4)-2,3-di-O-benzoyl-ꢁ-D-
xylopyranoside 14ꢀ
A solution of methyl (ethyl 4-O-benzoyl-2,3-di-O-benzyl-1-
thio-β--glucopyranosid)uronate (500 mg, 0.93 mmol) and 7
(442 mg, 0.62 mmol) in dry diethyl ether (10 ml) containing
powdered molecular sieves (4 Å) was stirred at 0 ЊC in an Ar
atmosphere for 30 min. To the mixture was added DMTST (642
1 M NaOMe (5 drops) was added to a solution of the hemi-
acetal (35 mg, 0.040 mmol) in MeOH (2 ml). After 2 h, water
(1 ml) was added to saponify the methyl ester. The mixture was
J. Chem. Soc., Perkin Trans. 1, 2001, 873–879
877

View Article Online
stirred for 3 h, then neutralised with 0.1 M HCl and concen-
trated. The residue was dissolved in water, washed successively
with diethyl ether and EtOAc, and subsequently purified on a
Bio-Gel P-2 column to give 17 (12 mg, 64%) after freeze-drying;
[α]D ϩ40 (c 0.4 in H2O); δC(D2O) 60.7 (4Љ-OMe), 62.0, 64.5,
64.9, 67.0, 71.5, 71.9, 73.0, 73.3, 74.3, 75.9, 76.3, 78.2, 78.3,
78.9, 83.7 (C-2–5, -2Ј–5Ј, -2Љ–5Љ), 93.9, 98.4, 99.7, 103.4 and
103.5 (C-1, -1Ј, -1Љ), 175.9 (C-6Љ); m/z 497.1 [M ϩ Na]ϩ.
-1Ј, -1Љ), 112.0 (C-4Љ), 114.4–155.2 (Ph), 140.5 (C-5Љ), 162.8
(C-6Љ), 165.1 and 165.3 (PhCO).
The diol (127 mg, 0.16 mmol) was stirred in acetic
anhydride–pyridine (1 : 1; 5 ml) at room temperature for 1 h,
when the mixture was diluted with toluene and concentrated.
Co-evaporation of the residue twice from toluene followed by
silica gel chromatography (toluene–EtOAc 3 : 1) yielded 20 (108
mg, 75%); [α]D ϩ49 (c 1 in CHCl3) (Found: C, 58.98; H, 5.28.
Calc. For C46H48O21: C, 58.97; H, 5.16%); δC(CDCl3) 20.4, 20.6,
20.6 and 20.8 (MeCO), 52.3 (6Љ-OMe), 55.5 (PMP-OMe), 60.1,
62.5, 66.2, 67.8, 68.7, 69.0, 69.5, 71.4, 73.5, and 75.2 (C-2–5,
-2Ј–5Ј, -2Љ, -3Љ), 95.9, 97.9 and 102.2 (C-1, -1Ј, -1Љ), 107.8 (C-4Љ),
114.4–155.0 (Ph), 141.9 (C-5Љ), 161.3 (C-6Љ), 164.7 and 164.9
(PhCO), 169.4 and 169.5 (MeCO).
p-Methoxyphenyl (methyl 2,3-di-O-acetyl-4-deoxy-ꢁ-L-threo-
hex-4-enopyranosyluronate)-(1→2)-(3,4-di-O-acetyl-ꢁ-D-xylo-
pyranosyl)-(1→4)-2,3-di-O-benzoyl-ꢁ-D-xylopyranoside 20
A solution of 7 (186 mg, 0.26 mmol) and 13 (200 mg, 0.39
mmol) in dry diethyl ether (15 ml) containing powdered
molecular sieves (4 Å) was stirred at 0 ЊC in an Ar atmosphere
for 30 min. To the mixture was added DMTST (270 mg, 1.04
mmol) and stirring was continued for 6 h. After neutralisation
with NEt3 (0.5 ml), the mixture was filtered through Celite and
concentrated. The residue was purified on a silica gel column
(toluene–EtOAc 6 : 1) to yield p-methoxyphenyl (methyl 2,3-
di-O-benzyl-4-O-methylsulfonyl-α--glucopyranosyluronate)-
(1→2)-[3,4-O-(2Ј,3Ј-dimethoxybutane-2Ј,3Ј-diyl)-β--xylo-
(4-Deoxy-ꢁ-L-threo-hex-4-enopyranosyluronic acid)-(1→2)-ꢁ-D-
xylopyranosyl-(1→4)-D-xylopyranose 21
CAN (70 mg, 0.13 mmol) was added to a cooled (0 ЊC) solution
of 20 (25 mg, 0.027 mmol) in CH3CN–water (2 : 1; 3 ml). The
reaction mixture was stirred for 30 min, then diluted with
EtOAc (20 ml) and washed successively with water and brine.
The organic phase was dried (MgSO4), filtered and concen-
trated to give the crude hemiacetal, which was directly dissolved
in acetic anhydride–pyridine (1 : 1; 2 ml) and the solution was
stirred overnight at room temperature. Dilution of the solution
with toluene followed by concentration and silica gel chromato-
graphy (toluene–EtOAc 3 : 1) afforded the anomeric acetate
(23 mg, 99%); δC(CDCl3) 20.5, 20.6 and 20.8 (MeCO), 52.4
(6Љ-OMe), 61.5, 62.5, 66.0, 67.8, 68.5, 68.7, 69.8, 71.3, 73.5 and
75.8 (C-2–5, -2Ј–5Ј, -2Љ, -3Љ), 91.3, 96.1 and 102.1 (C-1, -1Ј, -1Љ),
107.4 (C-4Љ), 128.0–133.2 (Ph), 142.3 (C-5Љ), 161.4 (C-6Љ), 164.7
and 164.9 (PhCO), 168.4, 169.5 and 169.6 and 169.7 (MeCO).
1 M NaOMe (5 drops) was added to a solution of the hemi-
acetal (23 mg, 0.028 mmol) in MeOH (2 ml). After 30 min,
water (1 ml) was added to hydrolyze the methyl ester and the
mixture was stirred for an additional 30 min. Dowex 50
(Hϩ) ion-exchange resin was added to neutralise the solution.
Filtration and concentration gave a crude product, which was
dissolved in water, washed with diethyl ether, and purified on a
Bio-Gel P-2 column to give 21 (8 mg, 64%) after freeze-drying;
[α]D ϩ57 (c 0.3 in H2O); δC(D2O) 59.4, 63.7, 65.8, 66.6, 69.8,
70.7, 71.7, 72.0, 74.6, 74.7, 74.9, 77.1, 77.3 and 78.6 (C-2–5,
-2Ј–5Ј, -2Љ, -3Љ), 92.6, 97.2, 98.8 and 102.2 (C-1, -1Ј, -1Љ), 107.7
(C-4Љ), 146.7 (C-5Љ), 169.6 (C-6Љ); m/z 464.2 [M ϩ Na]ϩ.
pyranosyl]-(1→4)-2,3-di-O-benzoyl-β--xylopyranoside
18
(244 mg, 80%); [α]D ϩ42 (c 1 in CHCl3); δC(CDCl3) 17.2 and
17.5 (BDA), 38.4 (OMs), 47.7 and 48.0 (BDA), 52.4 (6Љ-OMe),
55.5 (PMP-OMe), 61.3, 63.6, 65.5, 69.0, 69.8, 70.6, 70.8, 72.5,
73.2, 74.6, 75.5, 78.1, 78.8 and 79.3 (C-2–5, -2Ј–5Ј, -2Љ–5Љ,
PhCH2), 95.9, 98.9, 99.3, 100.0 and 102.4 (C-1, -1Ј, -1Љ, BDA),
114.3–155.2 (Ph), 164.9 and 165.0 (PhCO), 168.5 (C-6Љ).
Compound 18 (298 mg, 0.26 mmol) in EtOAc–MeOH–
water–HOAc 4 : 4 : 1 : 1 (10 ml) was hydrogenolyzed over
Pd(OH)2 on activated carbon powder at 100 psi for 24 h. Addi-
tional catalyst was added and the mixture was hydrogenolyzed
for another 16 h at 100 psi and then filtered through Celite. The
filter was washed with CH2Cl2 (50 ml) after which the filtrate
was concentrated to 10 ml, diluted with EtOAc (30 ml), washed
successively with water and saturated aq. NaHCO3, dried and
concentrated to give the crude 2Љ,3Љ-diol (218 mg, 87%);
δC(CDCl3) 17.3 and 17.5 (BDA), 38.5 (OMs), 47.8 and 47.9
(BDA), 52.4 (6Љ-OMe), 55.5 (PMP-OMe), 60.8, 63.6, 65.5, 68.8,
69.6, 70.4, 70.7, 71.3, 71.8, 73.8, 75.0 and 79.1, (C-2–5, -2Ј–5Ј,
-2Љ–5Љ), 97.4, 99.0, 99.4, 99.9 and 103.2 (C-1, -1Ј, -1Љ, BDA),
114.6–155.4 (Ph), 164.9 and 165.1 (PhCO), 168.4 (C-6Љ).
DBU (54 µl, 0.36 mmol) was added under nitrogen to the
crude diol (218 mg, 0.22 mmol) in dry CH2Cl2 (5 ml) and the
mixture was stirred at room temperature for 16 h. Additional
DBU (27 µl, 0.18 mmol) was then added and the mixture was
stirred for another 24 h, whereafter NH4Cl (saturated aq., 5 ml)
was added. The phases were separated and the water phase was
extracted twice with CH2Cl2 (10 ml). The combined organic
extracts were washed with water, dried and concentrated.
Purification on a silica gel column (toluene–EtOAc 1 : 2) gave
Acknowledgements
This project is a collaboration with the Swedish Pulp and Paper
Research Institute. We thank the Swedish Natural Science
Research Council for financial support. This article is dedicated
to Professor Göran Magnusson, in memory of an excellent
chemist and a very good friend.
p-methoxyphenyl
(methyl
4-deoxy-β--threo-hex-4-eno-
References
pyranosyluronate)-(1→2)-[3,4-O-(2Ј,3Ј-dimethoxybutane-
2Ј,3Ј-diyl)-β--xylopyranosyl]-(1→4)-2,3-di-O-benzoyl-β--
xylopyranoside 19 (141 mg, 72%); δC(CDCl3) 16.8 and 17.2
(BDA), 47.1 and 47.3 (BDA), 51.8 (6Љ-OMe), 55.2 (PMP-OMe),
60.8, 63.3, 65.1, 66.8, 69.4, 70.3, 70.9, 73.7 and 75.4 (C-2–5, -2Ј–
5Ј, -2Љ, 3Љ), 98.6, 98.9, 99.0, 99.1 and 102.8 (C-1, -1Ј, -1Љ, BDA),
111.5 (C-4Љ), 114.2–154.9 (Ph), 140.3 (C-5Љ), 162.0 (C-6Љ), 164.7
and 164.8 (PhCO).
Aq. CF3COOH (95%; 2 ml) was added to an ice-cooled solu-
tion of 19 (93 mg, 0.10 mmol) in CH3CN (1 ml) and the mixture
was stirred for 2 h, then diluted with toluene and evaporated.
Co-evaporation of the residue twice from toluene followed by
silica gel chromatography (CHCl3–MeOH 9 : 1) yielded the
3Ј,4Ј-diol (79 mg, 96%); δC(CDCl3) 52.7 (6Љ-OMe), 55.5
(PMP-OMe), 61.8, 65.0, 66.1, 69.3, 70.2, 70.4, 71.4, 74.7, 74.9
and 79.8 (C-2–5, -2Ј–5Ј, -2Љ, -3Љ), 98.8, 99.3 and 102.3 (C-1,
1 E. Sjöström, Wood Chemistry, Fundamentals and Applications,
Academic Press, New York, 1993, pp. 63–70.
2 N. Roy and T. E. Timell, Carbohydr. Res., 1968, 6, 482.
3 A. Rydlund and O. Dahlman, Carbohydr. Res., 1997, 300, 95.
4 A. Teleman, M. Siika-aho, H. Sorsa, J. Buchert, M. Perttula,
T. Hausalo and M. Tenkanen, Carbohydr. Res., 1996, 293, 1.
5 K. Li and R. F. Helm, Carbohydr. Res., 1995, 273, 249.
6 J. Hirsch, M. Koós and P. Kovác, Carbohydr. Res., 1998, 310, 145.
7 K. Jansson, S. Ahlfors, T. Frejd, J. Kihlberg and G. Magnusson,
J. Org. Chem., 1988, 53, 5629.
8 Z. Zhang and G. Magnusson, Carbohydr. Res., 1996, 295, 41.
9 R. López and A. Fernández-Mayoralas, J. Org. Chem., 1994, 59,
737.
10 R. F. Helm, J. Ralph and L. Anderson, J. Org. Chem., 1991, 56,
7015.
11 M. Gehrke and W. Kohler, Ber. Dtsch. Chem. Ges., Abt. B, 1931, 64,
2696.
878
J. Chem. Soc., Perkin Trans. 1, 2001, 873–879

View Article Online
12 S. V. Ley, H. W. M. Priepke and S. L. Warriner, Angew. Chem.,
Int. Ed. Engl., 1994, 33, 2290.
13 N. L. Douglas, S. V. Ley, H. M. I. Osborn, D. R. Owen, H. W. M.
Priepke and S. L. Warriner, Synlett, 1996, 793.
14 N. L. Douglas, S. V. Ley, U. Lücking and S. L. Warriner, J. Chem.
Soc., Perkin Trans. 1, 1998, 51.
15 P. Svahnberg, Licentiate Thesis, Stockholm University, 1999.
16 P. J. Garegg, I. Kvarnström, A. Niklasson, G. Niklasson and
S. C. T. Svensson, J. Carbohydr. Chem., 1993, 12, 933.
17 A. J. Mancuso, S.-L. Huang and D. Swern, J. Org. Chem., 1978, 43,
2480.
18 B. O’Connor and G. Just, Tetrahedron Lett., 1987, 28, 3235.
19 K. E. Pfitzner and J. G. Moffat, J. Am. Chem. Soc., 1963, 85, 3027.
20 K. E. Pfitzner and J. G. Moffat, J. Am. Chem. Soc., 1965, 87, 5661.
21 H. G. Bazin, M. W. Wolff and R. J. Linhardt, J. Org. Chem., 1999,
64, 144.
22 P. J. Garegg, L. Olsson and S. Oscarson, J. Org. Chem., 1995, 60,
2200.
23 C. Krog-Jensen and S. Oscarson, Carbohydr. Res., 1998, 308, 287.
24 H. Lönn, J. Carbohydr. Chem., 1987, 6, 301.
25 C. W. Andrews, R. Rodebaugh and B. Fraser-Reid, J. Org. Chem.,
1996, 61, 5280.
J. Chem. Soc., Perkin Trans. 1, 2001, 873–879
879