Highly efficient syntheses of hyaluronic acid oligosaccharides

Article abstract of DOI:10.1002/chem.200601090

Highly efficient syntheses of hyaluronic acid oligosaccharides have been accomplished through the pre-activation based iterative one-pot strategy. A series of oligosaccharides ranging from di- to hexasaccharides were rapidly assembled using only near stoi

Full text of DOI:10.1002/chem.200601090

FULL PAPER
DOI: 10.1002/chem.200601090
Highly Efficient Syntheses of Hyaluronic AcidOligosaccharides
[a]
Lijun Huang andXuefei Huang*
Abstract: Highly efficient syntheses of
hyaluronic acid oligosaccharides have
been accomplished through the pre-ac-
tivation based iterative one-pot strat-
egy. A series of oligosaccharides rang-
ing from di- to hexasaccharides were
rapidly assembled using only near stoi-
chiometric amounts of the building
blocks without aglycon adjustment or
purifications of intermediate oligosac-
charides. Deprotection and oxidation
protocols were developed for protec-
tive group removal and oxidation-state
adjustment. The availability of such
structurally well defined synthetic hya-
luronic acid oligosaccharides will great-
ly facilitate the establishment of de-
tailed structure–function relationships.
Keywords:
glycosylation
carbohydrates
hyaluronic acid
·
·
·
oligosaccharides
Introduction
up-regulate a heat-shock protein expression and suppress
cell death under stress conditions while the corresponding
di-, hexa- and octasaccharides are inactive.[10] However, in
most cases, detailed understandings of structure–activity re-
lationships remain to be established due to the lack of struc-
turally defined sHA. Access to synthetic sHA with distinct
length and sequence can greatly facilitate a systematic inves-
tigation of its structure–activity relationship, providing excit-
ing opportunities for the development of novel therapeutics
for a variety of diseases.
Chemical syntheses of sHA are typically carried out fol-
lowing two general approaches.[5,19] In the first method, glu-
curonic acid building blocks are directly utilized to react
with a glucosamine derivative.[20] The newly formed disac-
charide was transformed into either an acceptor by selective
deprotection or a glycosyl donor through aglycon adjust-
ment. Repetition of the glycosylation, selective deprotec-
tion, aglycon adjustment and glycosylation processes led to
the impressive synthesis of a sHA octasaccharide.[20] Due to
the low reactivity of glucuronic acid, as an alternative, more
reactive glucose can be used as building blocks.[21–27] With
this strategy, a selectively removable protective group must
be installed on the 6-hydroxyl group of glucose to allow for
oxidation-state adjustment. The complete deprotection and
oxidation of 6-OH on all glucose units can present signifi-
cant challenges.
Glycosaminoglycans (GAG) are a family of linear and nega-
tively charged oligosaccharides, which are involved in many
important biological processes such as lymphocyte traffick-
ing, tumor metastasis, inflammatory response, and neuron
growth.[1–6] As the only unsulfated GAG, hyaluronic acid
(HA) is comprised of tandem disaccharide repeats of b-1,4-
d-glucuronic acid-b-1,3-d-N-acetylglucosamine. Biological
studies of HA are receiving increased interests due to their
mediatory roles in cell adhesion, cell migration, innate im-
munity and wound healing.[2,7]
Endogenous HA can be transformed into hyaluronan oli-
gosaccharides (sHA) in vivo. sHA have novel biological
properties[8–18] distinct from high molecular weight (~2”
106 D) and low molecular weight (~8”104 D) HA polymers.
It has been reported that sHA can not only suppress tumor
cell growth[12] but also sensitize multidrug resistant tumor
cells towards a variety of chemotherapeutic drugs,[9] while
HA is ineffective. In addition, sHA have been shown to be
angiogenic, whereas their high molecular weight counter-
parts suppress angiogenesis.[17,18] It has become evident that
the biological activities of sHA are sequence specific,[10,14]
an example of which is the report that sHA tetrasaccharides
[a] Dr. L. Huang, Prof. X. Huang
All current sHA syntheses are characterized by their step-
wise nature, which require multiple protective group adjust-
ment, aglycon modification and purification of intermediate
oligosaccharides.[5,19–27] To facilitate biological studies of
sHA, a robust method needs to be developed so that fast
and efficient assembly of multiple sHA can be achieved.
Department of Chemistry, The University of Toledo
2801 W. Bancroft St. MS 602, Toledo OH 43606 (USA)
Fax : (+1)419-530-4033
E-mail: xuefei.huang@utoledo.edu
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
Chem. Eur. J. 2007, 13, 529 –540
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
529

Results andDiscussion
entry 1). However, even after the reaction temperature was
raised to room temperature, only donor hydrolysis product
was isolated without the desired disaccharide 3. In order to
improve the nucleophilicity of the acceptor, we replaced the
bulky phthalimido (Phth) moiety in 2 with trichloroethyl
carbamate (Troc) (acceptor 4).[36] However, this did not
result in any improvements. Glycosylation of acceptor 2
with glycosyl bromide 5 using promoter AgOTf or reaction
of acceptor 6[37] with donor 1 promoted by N-iodosuccini-
mide (NIS)/AgOTf did not produce significant amounts of
disaccharides. These results demonstrated low reactivities of
these glucuronic acid donors and pointing to the necessity of
using more reactive glucosyl donors.
Recently, we have developed a new reactivity independent
pre-activation based iterative one-pot oligosaccharide syn-
thesis method, where multiple sequential glycosylations can
be carried out in the same reaction vessel without inter-
mediate purification, allowing construction of oligosacchar-
ides within a few hours.[28,29] Moreover, unlike the traditional
reactivity based one-pot approach where glycosylation reac-
tions must be performed in the order of decreasing donor
anomeric reactivity values,[30,31] it is not necessary to fine-
tune anomeric reactivities using the pre-activation
method.[29] This is particularly advantageous for syntheses of
oligosaccharides, which consist of repeating units, as the
same building blocks can be used repeatedly without resort-
ing to anomeric reactivity adjustments.[28,29] Herein, we ex-
plore the applicability of the iterative one-pot method in
construction of the highly challenging sHA.
Peracetylated thioglucosyl donor 7[31] and p-methoxyben-
zylidene containing donor 8 were examined next with glu-
cosamine acceptors 2, 4, 9, and 10 under the pre-activation
condition, which did not produce much desired disacchar-
ides in dichloromethane, diethyl ether or a mixed solvent di-
chloromethane/diethyl ether system (Table 1, entries 2–8).
Finally, we decided to introduce the tert-butyldimethylsilyl
(TBS) moiety into the glucosyl donor (donor 11), due to
beneficial effects of TBS on glycosylation in our previous
chitotetraose syntheses.[28]
Thioglucosyl donor 11 was prepared from p-tolyl-1-thio-b-
d-glucopyranoside (16),[31] which was first protected with p-
methoxybenzylidene (Scheme 1). Dibutyltin oxide mediated
selective benzylation[38] followed by benzoylation gave thio-
glycoside 8 in 66% yield over three steps. Regioselective
opening of the p-methoxybenzylidene group and TBS pro-
tection produced donor 11 (90% yield for two steps). The p-
methoxybenzyl (PMB) moiety in 11 can be selectively re-
moved by oxidation in the presence of other protective
groups, which is crucial for future oxidation-state adjust-
ments.
Building block evaluations: Previous syntheses of sHA have
been dominated by the usage of powerful glycosyl trichlor-
oacetimidates.[5,19] We plan to examine the alternative of
using thioglycosides as building blocks, because thioglyco-
sides are stable to most functional group transformation and
yet can be easily activated by a wide range of thiophilic pro-
moters.[32,33] Moreover, they can be conveniently stored on
bench top for months without decomposition. Despite the
fact that thioglycosides have been one of the most popular
glycosyl donors in syntheses of complex oligosacchar-
ides,[32,33] they have been rarely used for sHA assembly.[34,35]
The direct usage of glucuronic acid as the glycosyl donor
was investigated first. Thioglucuronic acid 1 was activated in
the absence of an acceptor by p-TolSOTf, formed in situ by
reacting p-TolSCl with AgOTf at ꢀ658C,[29] which was fol-
lowed by addition of thioglycosyl acceptor 2 (Table 1,
The glycosylation of thioglucoside donor 11 with acceptor
2 was carried out first in diethyl ether (Table 1, entry 9). The
Table 1. Evaluations of building blocks.
desired thioglycosyl disaccharide 14b (1H NMR: dH1’
4.73 ppm, JH1’,H2’ =8.4 Hz) was obtained in 75% yield along
=
3
with 5% of the corresponding
a disaccharide 14a
(1H NMR: dH1’ = 5.48 ppm, JH1’,H2’ =4.2 Hz). The structure
of 14a was confirmed by the presence of Bz carbonyl in the
13C NMR spectrum with a chemical shift of dBz = 164.9 ppm
and a strong HMBC correlation between C1’ and H3. The
decrease in the stereospecificity of this reaction despite the
presence of participating benzoyl moiety on O2’ is due to
the competing a-directing effect of ethereal solvents,[39–44]
presumably through stabilization of the oxo-carbenium ion
by the oxygen lone pair of diethyl ether from the b-face,
leading to a-glycoside. To enhance the stereoselectivity, we
discovered that by simply adding the acceptor dissolved in
dichloromethane to the pre-activated donor in diethyl ether,
the formation of disaccharide 14a can be suppressed to neg-
ligible amount without affecting the yield of the desired b-
disaccharide (Table 1, entry 10).[45] Disaccharide 15 bearing
a methoxy group at the reducing end was also synthesized in
good yield by glycosylating methyl glycoside 6 with donor
11 (Table 1, entry 11).
3
Entry
Donor
Acceptor
Disaccharide (yield/%)
1
2
3
4
5
6
7
8
1
7
7
7
7
8
8
8
2
2
4
9
10
2
4
9
2
2
3 (< 5)
12a (< 5)
12b (< 10)
12c (< 5)
12d (< 20)
13a (< 5)
13b (< 5)
13c (< 5)
14b (75) 14a (5)[a]
14b (75)[b]
15 (88)[c]
9
10
11
11
11
11
6
[a] Acceptor 2 was added as a solution in diethyl ether to pre-activated
donor in diethyl ether. [b] Acceptor 2 was added as a solution in CH2Cl2
to pre-activated donor in diethyl ether. Final ratio of CH2Cl2/diethyl
ether 1:1. [c] Reaction was carried out by mixing donor and acceptor to-
gether in CH2Cl2/diethyl ether 1:1 followed by addition of the promoter.
530
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Chem. Eur. J. 2007, 13, 529 –540

Oligosaccharides
FULL PAPER
of disaccharide as the acceptor.
The disaccharides 14b and 15
were deprotected with HF·pyri-
dine producing thioglycoside 21
and disaccharide 22 in 92 and
87% yield, respectively (Sche-
me 2c). Gratifyingly, glycosyla-
tion of 21 by 14b formed tetra-
saccharide 23 in 75% yield
(Scheme 2d).
From results of these glycosy-
lations, we conclude that it is
advantageous to perform donor
pre-activation in diethyl ether
particularly for building blocks
having high anomeric reactivi-
ties (e.g. 11). This corroborates
with our observation that glyco-
sylation of glucoside 24 by the
reactive perbenzylated thioglu-
coside 25 proceeded cleanly in
diethyl ether in 75% yield,
while the corresponding reac-
tion in dichloromethane led to
a lower yield (~48%) with sev-
eral side products isolated resulting from donor decomposi-
tion. This may be due to stabilization of the reactive oxo-
carbenium ion intermediate by diethyl ether.
Scheme 1. Building block 11: a) p-methoxybenzylidene dimethyl acetal,
camphorsulfonic acid, DMF, 60–708C; b) nBu2SnO, toluene, reflux;
BnBr, CsF, DMF, 1408C; c) BzCl, N,N-dimethylaminopyridine, 66% for
three steps; d) NaCNBH3, TFA, MS-AW 300, DMF; e) TBSOTf, 2,6-luti-
dine, CH2Cl2, 90% for two steps.
Another important factor to consider in the synthesis is
solubilities of the building blocks because the reactions are
carried out at low temperatures. The TBS moiety in thiogly-
coside donor 11 renders it more soluble in diethyl ether
compared with donor 8, leading to significantly improved
yields in reaction with acceptor 2. Higher glycosylation
yields obtained with disaccharide 21 (Scheme 2d) versus
monosaccharide acceptor 17 (Scheme 2a) can also be parti-
ally attributed to better solubility of disaccharide 21 in the
reaction medium.
With the thiotolyl moiety at its reducing end, disaccharide
14b was directly used as a glycosyl donor without any agly-
con adjustments. Glycosylation of acceptor 17 by disacchar-
ide 14b formed trisaccharide 18 in 50% yield with 20% of
the hydrolyzed donor as the major side product (Sche-
me 2a). Reaction of trisaccharide 18 with the o-glycoside ac-
ceptor 6 led to the desired tetrasaccharide 19 in 47% yield
(Scheme 2b). Small amount of trisaccharide 20 could also be
isolated from the reaction mixture, which was formed due to
the assistance of electron rich 6-OPMB in stabilization of
the oxo-carbenium ion followed by removal of the p-me-
thoxybenzyl moiety. This long range participation by 6-O
protective group has been reported when the glycosyl donor
contains a participating group on 6-OH.[39,46,47] Although we
have obtained the tetrasaccharide, the yields for formation
of tri- and tetrasaccharides are not sufficiently high enough
to enable one-pot synthesis. We investigated next the usage
One-pot syntheses of sHA: With suitable building blocks
and reaction conditions identified, one-pot syntheses were
performed. Pre-activation of donor 11 (1 equiv) by p-Tol-
SOTf was followed by addition of 2 (0.9 equiv) and a steri-
cally hindered non-nucleophilic base 2,4,6-tri-tert-butylpyri-
midine (TTBP).[48] The reaction was allowed to proceed for
90 minutes resulting in the complete disappearance of ac-
ceptor 2 based on TLC analysis. The reaction mixture was
then warmed up to 08C for 15 minutes to decompose the
slight excess of activated donor, and cooled back down to
ꢀ658C. Addition of the second acceptor 22 (0.81 equiv) and
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531

X. Huang and L. Huang
reaction protocol A produced
pentasaccharide 28 (65% yield)
(Table 2, entry 2, protocol A).
The other possible pentasac-
charide sequence 29 with glu-
cose at the reducing end was
rapidly synthesized through
consecutive condensations of
four components, that is, 11, 2,
21 and 27[25] (Table 2, entry 3,
protocol B), in 55% overall
yield for the one-pot reactions.
Because it is unnecessary to
achieve the precise anomeric re-
activities with our pre-activation
based one-pot strategy,[29] build-
ing blocks can be pooled to
generate various sHA without
anomeric reactivity adjustment.
Following the exact reaction se-
quence for the one-pot synthe-
sis of 19 except for the insertion
of 21 as the second acceptor,
Scheme 2.
TTBP to the reaction mixture
followed by activation with p-
TolSOTf produced sHA tetra-
saccharide 19 in 64–75% over-
all yield in just three hours
(Table 2, entry 1), which was
the only compound needed pu-
rification in this three compo-
nent one-pot synthesis.
sHA sequences containing
odd number of monosaccharide
units can also be synthesized.
Sequential one-pot reactions of
26,[28] 21 and 22 following the
Table 2. Iterative one-pot synthesis of sHA. The values in the parenthesis denote the number of equivalents
of each reagent.[a]
sHA hexasaccharide 30 was
produced in 54–60% yield
(Table 2, entry 4, protocol B),
which corresponded to an aver-
age of 90% yield for the five
synthetic steps carried out in a
one-pot reaction.
With close to stoichiometric
amounts of building blocks
used for each glycosylation re-
action and no oligosaccharide
intermediate purification in-
volved, these syntheses can be
easily scaled up. Near gram
quantity of sHA hexasaccharide
30 was obtained within several
Protocol
Donor
Acceptor 1 (A1)
Acceptor 2 (A2)
Acceptor 3 (A3)
Product
Yield/%
1
2
3
4
A
A
B
B
11
26
11
11
2
21
2
22
22
21
21
19
28
29
30
64–75
65
55
27
22
2
54–60
[a] Reagents and conditions: a) AgOTf, p-TolSCl, ꢀ658C, 10 min; then acceptor, TTBP, 90 min to 08C;
15 min, 08C; b) acceptor, TTBP, AgOTf, p-TolSCl, ꢀ65! 08C in 90 min.
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Oligosaccharides
FULL PAPER
hours in similar yields as the smaller scale. In comparison,
the overall yield for the traditional stepwise synthesis of a
sHA hexasaccharide was 27% for five synthetic steps start-
ing from an advanced disaccharide building block.[22] In ad-
dition, it required multiple chromatography separations of
synthetic intermediates. The scalability coupled with the
speed of glycoassembly and higher overall yields highlights
the advantages of using the iterative one-pot approach for
complex oligosaccharide synthesis.
Deprotection of sHA: Deprotection of large complex oligo-
saccharides can be a highly challenging task due to the pres-
ence of large number of protective groups. This is further
compounded by the necessity of oxidation-state adjustment
in sHA synthesis and thus the need to differentiate 6-hy-
droxyl groups of the glucose units from others. Treatment of
hexasaccharide 30 with HF·pyridine cleanly removed the
TBS moiety and the resulting free hydroxyl group was pro-
tected by acetate. Although it has been reported that a
PMB group was easily removed by cerium ammonium ni-
trate (CAN) or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
(DDQ) oxidation from hyaluronan di- and trisacchar-
ides,[21,25] cleavage of all three PMB groups in 32 turned out
to be very problematic. Treatment of 32 with CAN or DDQ
both failed to produce the desired triol 33 in good yields
with multiple decomposition products formed. Simultaneous
removal of the phthalimide, acetate and benzoyl groups in
32 followed by per-acetylation led to hexasaccharide 34 in
50% yield. Unfortunately, CAN or DDQ oxidation of 34
again did not generate the desired triol 35 either. Surprising-
ly, we discovered that the presence of TBS moiety was bene-
ficial for deprotection of PMB, as CAN oxidation of hexa-
saccharide 30 produced triol 36
Scheme 3. a) HF·pyridine; b) Ac2O, pyridine; c) CAN, CH3CN, H2O; d)
DDQ, H2O, CH2Cl2; e) NH2CH2CH2NH2, nBuOH, 808C then Ac2O, pyr-
idine; f) TEMPO, NaOCl, NaBr, Bu4NBr, NaHCO3, then NaClO2, 2-
methy-2-butene, NaH2PO4; PhCHN2; g) H2, Pd(OH)2; CH3NH2 then
Ac2O, MeOH.
cleanly, which was followed by benzyl ester formation with
phenyl diazomethane producing ester 37.[60] Removal of
TBS, catalytic hydrogenation, transamidation with methyl
amine and selective acetylation led to fully deprotected
sHA hexasaccharide 38 in 44% overall yield from 36 (Sche-
me 3b). Identical deprotection sequences on sHA 15, 19, 28,
and 29 provided free sHA oligosaccharides 39–42 in good
overall yields (Scheme 3c). sHA sequences obtained through
enzymatic degradation are limited to oligosaccharides con-
taining even number of monosaccharide units.[11,13] This is
the first time that the sHA pentasaccharide sequence 41 has
been acquired through either chemical synthesis or degrada-
tion.
in 74% yield (Scheme 3a).
Subsequent
oxidation-state
adjustment of 36 to tricarboxyl-
ic acid proves to be non-trivial.
In contrast to literature results,
2,2,6,6-tetramethylpiperidinyl-1-
oxy (TEMPO)/NaOCl[21,49–56] or
TEMPO/iodobenzene
diace-
tate[57] oxidation led to a mix-
ture of partially oxidized prod-
ucts, which is probably due to
the hydrophobic nature of our
fully protected oligosacchar-
ides.[58] A two-step process of
Dess–Martin oxidation and sub-
sequent
NaClO2
treatment
also gave inconsis-
with
[59]
tent results. Through extensive
experimentation, we discovered
that with a two-step one-pot ox-
idation protocol of NaOCl/
TEMPO followed by addition
of NaClO2,[58] we were able to
carry out this transformation
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533

X. Huang and L. Huang
sumed judged by TLC. A solution of acceptor 1 (0.289 mmol) and TTBP
(80 mg, 0.321 mmol) in anhydrous CH2Cl2 (10 mL) was added slowly to
the pre-activated donor along the wall of the reaction flask. The reaction
was continued for 90 min from ꢀ65 to 08C. A solution of acceptor 2
(0.261 mmol) and TTBP (71 mg, 0.289 mmol) in anhydrous CH2Cl2
(10 mL) was added and the resulted solution was cooled down to ꢀ658C
followed by the addition of AgOTf (200 mg, 0.783 mmol) in Et2O (8 mL)
and p-TolSCl (45 mL, 0.289 mmol). The reaction was stirred for 90 min
from ꢀ65 to 08C and quenched with triethylamine (300 mL). The ob-
tained reaction mixture was concentrated under reduced pressure, re-sus-
pended in CH2Cl2 (50 mL) and filtered. The filtrate was concentrated
and purified by flash column chromatography (hexanes, EtOAc and
CH2Cl2) to afford the desired product.
Conclusion
We have developed highly efficient syntheses of sHA oligo-
saccharides through the pre-activation based iterative one-
pot strategy. Glycoassemblies were accomplished rapidly
using only near stoichiometric amounts of building blocks
without aglycon adjustment or purification of intermediate
oligosaccharides. Reaction solvents and protective groups
are important to ensure high yielding glycosylations. The se-
quence of deprotection is found to be crucial for oxidation-
state adjustments and protective group removal. Preliminary
studies indicate that this methodology can also be applied to
syntheses of other GAGs, such as chondroitin and heparin
oligosaccharides. We anticipate that the availability of these
structurally well defined sHA will greatly facilitate our un-
derstanding of the versatile biological roles of sHA.
Protocol B: The mixture of donor (230 mg, 0.321 mmol) and freshly acti-
vated MS 4 Š (500 mg) in anhydrous Et2O (10 mL) was stirred for 1 h at
room temperature, then cooled to ꢀ658C. A solution of AgOTf (250 mg,
0.96 mmol) in Et2O (10 mL) was added directly to the solution without
touching the wall of the reaction flask. After 10 min at ꢀ658C, p-TolSCl
(50 mL, 0.321 mmol) was added via a syringe. The mixture was stirred for
5 min until the yellow color dissipated and donor was consumed judged
by TLC. A solution of acceptor 1 (0.289 mmol) and TTBP (71 mg,
0.289 mmol) in anhydrous CH2Cl2 (10 mL) was added slowly to the pre-
activated donor along the wall of the reaction flask. The reaction was
continued for 90 min from ꢀ65 to 08C and cooled back down to ꢀ658C.
To the reaction mixture, AgOTf (220 mg, 0.866 mmol) in Et2O (8 mL)
and p-TolSCl (45 mL, 0.289 mmol) were sequentially added. The mixture
was stirred for 15 min until no donor was left when a solution of acceptor
2 (0.255 mmol) and TTBP (71 mg, 0.289 mmol) in anhydrous CH2Cl2
(10 mL) was added slowly. The reaction was kept for 90 min from ꢀ65 to
08C. Then acceptor 3 (0.261 mmol) and TTBP (63 mg, 0.253 mmol) in an-
hydrous CH2Cl2 (10 mL) was added. The mixture was cooled down to
ꢀ658C followed by the sequential addition of AgOTf (200 mg,
0.783 mmol) in Et2O (8 mL) and p-TolSCl (41 mL, 0.261 mmol). The reac-
tion was stirred for 90 min from ꢀ65 to 08C and quenched with triethyla-
mine (400 mL). The obtained reaction mixture was concentrated under
reduced pressure, re-suspended in CH2Cl2 (100 mL) and filtered. The fil-
trate was concentrated and purified by flash column chromatography
(hexanes, EtOAc and CH2Cl2) to afford the desired product.
Experimental Section
General conditions: Chemicals used were reagent grade as supplied
except where noted. All reactions were performed under a nitrogen at-
mosphere unless specified otherwise. Analytical thin-layer chromatogra-
phy was performed using silica gel 60 F254 glass plates (EM Science);
compound spots were visualized by UV light (254 nm) and/or by staining
with
a
solution
containing
Ce
A
(NO3)6
(0.5 g)
and
(NH4)6Mo7O24·4H2O (24.0 g) in 6% H2SO4 (500 mL) or a solution of
KMnO4 (3 g), K2CO3 (20 g) and NaOH (0.25 g) in water (300 mL). Flash
column chromatography was performed on silica gel 60 (230–400 mesh,
EM Science). 1H NMR and 13C NMR spectra were recorded on a Varian
VXRS-400 or Inova-600 instrument and were referenced using Me4Si
(0 ppm), residual CHCl3 (d 1H NMR 7.26 ppm) CDCl3 (d 13C NMR
77.0 ppm), residual CHDCl2 (d 1H NMR 5.32 ppm), CD2Cl2 (d 13C NMR
54.0 ppm). ESI mass spectra were recorded on an ESQUIRE LC-MS op-
erated in both positive and negative ion mode. High-resolution mass
spectra were recorded on a Micromass electrospray Tof II (Micromass,
Wythenshawe, UK) mass spectrometer equipped with an orthogonal elec-
trospray source (Z spray) operated in positive ion mode, which is located
at the Mass Spectrometry and Proteomics Facility, the Ohio State Univer-
sity.
General procedures for deprotection and oxidation-state adjustment
Deprotection of PMB: An aqueous solution (2.5 mL) of CAN (1.16 g,
2.14 mmol) was added at 08C to a solution of the PMB-protected com-
pound (0.42 mmol) in acetonitrile (10 mL). The reaction mixture was stir-
red for 1 h from 08C to room temperature then diluted with EtOAc
(100 mL) and washed with water (30 mL) three times. The organic
phases were collected and dried over MgSO4. The obtained residue was
purified by flash column chromatography to give the desired product.
General procedure for pre-activation based single-step glycosylation: The
reaction mixture of donor (0.321 mmol) and freshly activated MS 4 Š
(500 mg) in anhydrous Et2O (10 mL) was stirred for 1 h at room tempera-
ture, then cooled to ꢀ658C. A solution of AgOTf (250 mg, 0.96 mmol) in
Et2O (10 mL) was added directly to the solution without touching the
wall of the reaction flask. After 10 min at ꢀ658C, p-TolSCl (50 mL,
0.321 mmol) was added via a syringe. The mixture was stirred for 5 min
until the yellow color dissipated and the donor was completely consumed
judged by TLC. A solution of acceptor 1 (0.289 mmol) and TTBP
(80 mg, 0.321 mmol) in anhydrous CH2Cl2 (10 mL) was added slowly to
the pre-activated donor along the wall of the reaction flask. The reaction
was continued for 90 min from ꢀ65 to 08C and quenched with triethyla-
mine (500 mL). The obtained reaction mixture was concentrated under
reduced pressure, re-suspended in CH2Cl2 (50 mL) and filtered. The fil-
trate was concentrated and purified by flash column chromatography
(hexanes, EtOAc and CH2Cl2) to afford the desired product.
Oxidation of alcohols to carboxylic acids: A 1m aqueous solution of
NaBr (25 mL), 1m aqueous solution of tetrabutylammonium bromide
(50 mL), TEMPO (2.2 mg, 0.014 mmol, 0.3 equiv per hydroxyl group) and
a saturated aqueous solution of NaHCO3 (125 mL) were added to a solu-
tion of the alcohol (0.045 mmol) in CH2Cl2 (1 mL) and H2O (170 mL)
cooled with an ice-water bath. The resulted mixture was treated with an
aqueous solution of NaOCl (150 mL, chlorine content not less than 4%)
and continuously stirred for 1 h from 08C to RT. The reaction media was
neutralized with 1n HCl (about 50 mL) to pH 6–7. It is important to keep
the acidity of the reaction close to neutral as lower pH had resulted in
formation of large amount of hemiacetal side product. After neutraliza-
tion, tBuOH (0.7 mL), 2m 2-methyl-but-2-ene (1.4 mL) in THF and a sol-
ution of NaClO2 (50 mg, 0.44 mm) and NaH2PO4 (40 mg, 0.34 mm) in
water (200 mL) were added. The reaction mixture was kept at room tem-
perature for 1–2 h, diluted with saturated aqueous NaH2PO4 solution
(5 mL) and extracted with EtOAc (10 mL) three times. The organic
layers were combined and dried over MgSO4. After removal of the sol-
vent, the desired compound was purified by flash column chromatogra-
phy (hexanes, EtOAc + 1% AcOH).
General procedures for one-pot synthesis of oligosaccharide
Protocol A: The mixture of donor (0.321 mmol) and freshly activated
MS 4 Š (500 mg) in anhydrous Et2O (10 mL) was stirred for 1 h at room
temperature, then cooled to ꢀ658C. A solution of AgOTf (250 mg,
0.96 mmol) in Et2O (10 mL) was added directly to the solution without
touching the wall of the reaction flask. After 10 min at ꢀ658C, p-TolSCl
(50 mL, 0.321 mmol) was added via a syringe. The mixture was stirred for
5 min until the yellow color dissipated and the donor was completely con-
Benzyl ester formation: The crude product from the oxidation reaction
was dissolved in dichloromethane (5 mL) and treated with phenyl diazo-
methane solution in diethyl ether (~2 equiv per acid) for 2–3 h until the
534
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 529 –540

Oligosaccharides
FULL PAPER
disappearance of all starting material as judged by TLC. The residue
after evaporation was purified by flash column chromatography to pro-
vide the benzyl ester.
bons), 155.2; ESI-MS: m/z: calcd for C23H25Cl3NNaO6S: 571.1, found:
571.0 [M+Na]+.
p-Tolyl 2-O-benzoyl-3-O-benzyl-4,6-O-p-methoxybenzylidene-1-thio-b-d-
glucopyranoside (8): The solution of p-tolyl-1-thio-b-d-glucopyranoside
16 (10 g, 35 mmol), p-anisaldehyde dimethyl acetal (7.1 mL, 42 mmol)
and camphorsulfonic acid (1.6 g, 7 mmol) in anhydrous DMF (80 mL)
was swirled on a rotary evaporator under aspirator pressure at 508C for
3 h, then was warmed up to 708C to remove methanol generated until
the reaction was completed judging by TLC. The resulting solution was
diluted with diethyl ether (150 mL) followed by washing with saturated
NaHCO3 and drying over MgSO4. The residue was purified by flash
column chromatography (hexanes/EtOAc 5:5 ! 3:7) to afford the de-
sired diol p-tolyl 4,6-O-p-methoxybenzylidene-1-thio-b-d-glucopyrano-
side (13 g, 92%) after purification. 1H NMR (400 MHz, CDCl3): d=2.36
Removal of TBS: The TBS-protected compound (0.5 mmol) was dis-
solved in pyridine (4 mL) in a plastic flask followed by the addition of
65–70% HF·pyridine solution (4 mL, diluted with 2 mL pyridine) at 08C.
The solution was stirred for 48 h until complete disappearance of the
starting material as judged from TLC analysis. The reaction mixture was
diluted with EtOAc (30 mL) and washed with 10% aqueous CuSO4 solu-
tion (20 mL). The aqueous phase was extracted with EtOAc (30 mL)
twice and the combined organic layers were washed with saturated aque-
ous NaHCO3 solution (3”50 mL). After drying over MgSO4 and concen-
trated, the obtained residue was purified by flash column chromatogra-
phy (hexanes/EtOAc) to give the desired product.
(s, 3H, CH3), 2.71 (br, 1H, OH), 2.81 (br, 1H, OH), 3.42 (t, 3J
8.8 Hz, 1H), 3.46–3.49 (m, 2H), 3.74 (t, 3J
(H,H)=10.0 Hz, 1H), 3.77 (s,
3H, OCH3), 3.82 (t, 3J(H,H)=8.8 Hz, 1H), 4.36 (dd, 3J
(H,H)=4.0,
10.0 Hz, 1H), 4.54 (d, 3J
(H,H)=10.0 Hz, 1H), 5.47 (s, PhCH), 6.87–7.44
(H,H)=
Hydrogenation: Pd(OH)2 (80 mg) was added to a solution of the oligo-
saccharide (0.045 mmol) in THF (1.5 mL), MeOH (2 mL) and acetic acid
(1.5 mL). The reaction flask was evacuated using a water aspirator and
filled with hydrogen. The process was repeated two times and the reac-
tion mixture was stirred under hydrogen atmosphere until a single de-
sired peak was observed by ESI mass spectrum (~48 h). The solution was
filtered and concentrated to provide the crude product.
AHCTREUNG
A
ACHTREUNG
AHCTREUNG
(m, 8H); 13C NMR (100 MHz, CDCl3): d=21.4, 55.2, 68.6, 70.6, 72.8,
74.8, 80.4, 88.8, 102.0, 114.0–138.8 (aromatic carbons); ESI-MS: m/z:
calcd for C21H25O6S: 405.3, found: 405.2 [M+H]+.
The diol p-tolyl 4,6-O-p-methoxybenzylidene-1-thio-b-d-glucopyranoside
(8.5 g, 21 mmol) was heated under reflux with Bu2SnO (5.7 g, 23 mmol)
in a flask equipped with a Dean–Stark device in anhydrous toluene
(400 mL) for 3 h and concentrated to approximate 100 mL. After cooling
the reaction mixture down to room temperature, anhydrous DMF
(150 mL dried over 5% w/v MS 4 Š twice overnight) was added followed
by addition of CsF (3.5 g, 23 mmol) and BnBr (2.76 mL, 23.1 mmol) and
the obtained solution was stirred for 4 h at 1408C. After the reaction was
complete, DMF was removed under reduced pressure. The residue was
dissolved in CH2Cl2 and extracted by 1m aqueous solution of KF. The or-
ganic phase was dried over MgSO4 and purified by flash column chroma-
tography (hexanes/EtOAc/CH2Cl2 5:1:1) to offer the desired product p-
tolyl 3-O-benzyl-4,6-O-p-methoxybenzylidene-1-thio-b-d-glucopyranoside
Removal of benzoyl andphthalimido groups by MeNH 2: The crude prod-
uct from hydrogenation was treated with 33% methyl amine solution in
ethanol (1 mL per mmol of compound) until only the desired peak was
observed by ESI mass spectrum (~72 h).
Acetylation: The crude reaction product from methyl amine treatment
(0.05 mmol) was dissolved in methanol (2 mL) followed by addition of
acetic anhydride (5 equiv) and triethylamine at 08C. The reaction was
run for 2–3 h, and treated with Amberlite IR-120 for 30 min. After filtra-
tion, the solvents were removed and the residue was dissolved in water
(5 mL), washed with Et2O (3 mL) and purified by Sephadex G-15 size-
exclusion chromatography and anion-exchange chromatography (DE 52,
Whatman) to give the desired product.
1
p-Tolyl-2,3,4-tri-O-acetyl-1-thio-b-d-glucopyranuronic acidmethyl ester
(1): p-TolSH (312 mg, 2.52 mmol) and tetrabutylammonium iodide
(465 mg, 1.26 mmol) at room temperature were added to a solution of
bromo-2,3,4-tri-O-acetyl-a-d-glucopyranuronic acid methyl ester (5;
500 mg, 1.26 mmol) in EtOAc (5 mL) and 1m aqueous Na2CO3 (5 mL).
The reaction was stirred for 1 h until no starting material was observed
by TLC. Extraction by EtOAc and washing of the organic layer with sa-
turated NaHCO3 followed by flash column chromatography gave com-
pound 1 (499 mg, 90%). 1H NMR (400 MHz, CDCl3): d=1.99 (s, 3H,
OAc), 2.01 (s, 3H, OAc), 2.09 (s, 3H, OAc), 2.35 (s, 3H, OCH3), 3.76 (s,
(8.4 g, 80%). H NMR (400 MHz, CDCl3): d=2.35 (s, 3H, CH3), 2.52 (br,
1H, OH), 3.44–3.51 (m, 2H), 3.61 (t, 3J
ACHTREUNG
3J
OCH3), 4.36 (dd, 3J
1H), 4.77 (d, 3J
A
ACHTREUNG
E
ACHTREUNG
U
ACHTREUNG
5.52 (s, 1H, PhCH), 6.88–7.43 (m, 13H); ESI-MS: m/z: calcd for
C28H30NaO6S: 517.6, found: 517.7 [M+Na]+.
p-Tolyl 3-O-benzyl-4,6-O-p-methoxybenzylidene-1-thio-b-d-glucopyrano-
side (7.5 g, 15.2 mmol) was treated with benzoyl chloride (2.12 mL,
18.2 mmol), N,N-dimethylaminopyridine (DMAP, 4.4 g, 36.4 mmol) in an-
hydrous CH2Cl2 (50 mL) overnight at room temperature. The reaction
mixture was washed with an aqueous NH4Cl solution (30 mL) and an
aqueous saturated NaHCO3 solution (30 mL) followed by drying over
MgSO4. The desired product 8 was obtained (8.2 g, 90%) after purifica-
tion by flash column chromatography (hexanes/EtOAc/CH2Cl2 4:1:1).
3H, CO2CH3), 4.10 (d, 3J
10.0 Hz, 1H), 4.93 (t, 1H, 3J
9.6 Hz, 1H), 5.25 (t, 3J(H,H)=9.6 Hz, 1H), 7.13 (d, 3J
2H), 7.39 (d, 3J(H,H)=12 Hz, 2H); 13C NMR (100 MHz, CDCl3): d=
A
ACHTREUNG
A
ACHTREUNG
A
ACHTREUNG
ACHTREUNG
20.7, 20.8, 21.0, 21.4, 53.1, 69.4, 69.9, 73.5, 76.4, 86.4, 127.3, 130.0, 134.2,
139.2, 167.1, 169.3, 169.5, 170.3; ESI-MS: m/z: calcd for C21H24NaO6S:
463.1, found: 463.2 [M+Na]+.
1H NMR (400 MHz, CDCl3): d=2.32 (s, 3H, CH3), 3.75 (dt, 3J
ACHTREUNG
4.8, 9.2 Hz, 1H), 3.78 (t, 3J
ACHTREUNG
3
3
ACHTREUNG
3.78–3.84 (m, 1H), 3.86 (t, J
G
p-Tolyl-2-deoxy-2-N-Troc-4,6-O-benzylidene-b-d-glucopyranoside
(4):
3
3
ACHTREUNG
10.0 Hz, 1H), 4.64 (d, J
(H,H)=12.0 Hz, 1H), 4.77 (d, J
The solution of compound 2 (1.25 g, 2.48 mmol) and ethylenediamine
(2 mL) in n-butanol (15 mL) was refluxed for 1.5 h until no starting mate-
rial was observed by TLC. The solution was dried under reduced pres-
sure followed by chromatography to afford free amine (881 mg, 95%).
The free amine (750 mg, 2.16 mmol) was dissolved in a biphasic system
of aqueous saturated NaHCO3 (15 mL) and THF (15 mL) followed by
addition of 2,2,2-trichloroethoxy chloroformate (349 mL, 2.60 mmol) at
08C. The reaction was stirred for 1 h and diluted with dichloromethane
followed by extraction and flash chromatography to provide the desired
1H), 4.78 (d, 3J(H,H)=12.0 Hz, 1H), 5.25 (dd, 3J
U
1H), 5.56 (s, 1H, PhCH), 6.90–8.05 (m, 18H); 13C NMR (100 MHz,
CDCl3): d=21.4, 55.5, 68.8, 70.8, 72.3, 74.4, 79.6, 81.6, 87.4, 101.5, 113.9–
138.8 (aromatic carbons), 160.3, 165.2 (carbonyl groups); ESI-MS: m/z:
calcd for C35H35O7S: 599.2, found: 599.0 [M+H]+.
p-Tolyl 4,6-O-benzylidene-2-deoxy-2-N-trichloroacetyl-b-d-glucopyrano-
side (9): A solution of compound 2 (1.25 g, 2.48 mmol) and ethylenedia-
mine (2 mL) in n-butanol (15 mL) was heated under reflux for 1.5 h until
no starting material was observed by TLC. The solution was dried under
reduced pressure followed by chromatography to afford free amine
(881 mg, 95%). The free amine (534 mg, 1.43 mmol) was dissolved in an-
hydrous THF (3 mL) followed by addition of triethylamine (216 mg,
2.14 mmol) and trichloroacetyl chloride (167 mL, 1.50 mmol) at 08C. The
reaction was stirred for 1 h and diluted with dichloromethane followed
by extraction and flash chromatography (hexanes/EtOAc 3:1) to provide
product
4
(1.40 g, 99%). 1H NMR (400 MHz, CDCl3
+
1
drop of
(H,H)=
(H,H)=4.4,
(H,H)=10.0 Hz,
CD3OD): d=2.26 (s, 3H, CH3), 3.36–3.48 (m, 3H), 3.71 (t, 3J
ACHTREUNG
10.0 Hz, 1H), 3.77 (t, 3J
A
ACHTREUNG
3
3
ACHTREUNG
10.0 Hz, 1H), 4.62 (d, J
(H,H)=12.0 Hz, 1H), 4.75 (d, J
1H), 4.77 (d, 3J
(H,H)=12.0 Hz, 1H), 5.47 (s, 1H, PhCH), 7.03–7.42 (m,
U
9H); 13C NMR (100 MHz, CDCl3 + 1 drop of CD3OD): d=21.2, 57.4,
68.7, 70.5, 72.3, 74.7, 81.4, 87.8, 95.7, 101.9, 126.4–138.5 (aromatic car-
Chem. Eur. J. 2007, 13, 529 –540
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
535

X. Huang and L. Huang
1
desire product 9 (740 mg, 99%). H NMR (400 MHz, CDCl3 + 1 drop of
CD3OD): d=2.25 (s, 3H, CH3), 3.42–3.45 (m, 2H), 3.61 (t, 3J
(H,H)=
10.2 Hz, 1H), 3.69 (t, 3J(H,H)=10.2 Hz, 1H), 3.93 (t, 3J
(H,H)=9.6 Hz,
1H), 4.24 (dd, 3J(H,H)=4.2, 10.2 Hz, 1H), 4.93 (d, 3J
(H,H)=10.2 Hz,
dried followed by separation by flash column chromatography (hexanes/
EtOAc/CH2Cl2 20:1:1) to give target molecule 11 (6.27 g, 90%) along
with a 1:1 mixture (~5%) of compound 11 with its regioisomer p-tolyl 2-
O-benzoyl-3-O-benzyl-6-O-tert-butyldimethylsilyl-4-O-p-methoxybenzyl-
1-thio-b-d-glucopyranoside. 1H NMR (400 MHz, CDCl3): d=ꢀ0.05 (s,
3H, CH3Si), 0.00 (s, 3H, CH3Si), 0.85 (s, 9H, (CH3)3CSi), 2.30 (s, CH3,
3H), 3.57–3.69 (m, 4H), 3.80–3.84 (m, 1H), 3.82 (s, 3H, OCH3), 4.45 (d,
AHCTREUNG
G
ACHTREUNG
G
ACHTREUNG
1H), 5.45 (s, 1H, PhCH), 7.03–7.39 (m, 9H); 13C NMR (100 MHz, CDCl3
+ 1 drop of CD3OD): d=21.3, 57.3, 68.7, 70.6, 71.4, 81.5, 86.8, 101.9,
126.4–138.8 (aromatic carbons), 165.6 (carbonyl group); ESI-MS: m/z:
calcd for C22H22Cl3NNaO5S: 541.8, found: 542.1 [M+Na]+.
3J
2H), 4.75 (d, 3J
A
ACHTREUNG
A
ACHTREUNG
p-Tolyl-2-deoxy-2-azido-4,6-O-benzylidene-1-thio-a-d-glucopyranoside
(10): Borontrifluoride etherate (15 mL, 120 mmol) was added slowly at
08C under an atmosphere of N2 to a solution of 2-deoxy-2-azido-3,4,6-tri-
O-acetyl-a/b-d-glucopyranosyl acetate[61] (7.6 g, 20 mmol) and p-TolSH
(3.72 g, 30 mmol) in dichloromethane (50 mL). The reaction was kept at
room temperature for 5 d and carefully quenched with saturated aqueous
solution of NaHCO3. The aqueous layer was then separated and washed
twice with dichloromethane. The organic layers were combined and dried
over Na2SO4. p-Tolyl-2-deoxy-2-azido-3,4,6-tri-O-acetyl-1-thio-a/b-d-glu-
copyranoside (6.0 g, 13.7 mmol, 70%) was isolated by flash chromatogra-
phy (hexanes/EtOAc 2:1).
6.87–7.99 (m, 18H); 13C NMR (100 MHz, CDCl3): d=ꢀ4.5, ꢀ3.5, 18.2,
21.4, 26.2, 55.5, 69.5, 71.3, 73.2, 73.4, 75.4, 81.2, 85.0, 86.6, 113.9–138.0 (ar-
omatic carbons), 159.4, 165.4 (carbonyl groups); HRMS: m/z: calcd for
C41H50NaO7SSi: 737.2944, found: 737.2953 [M+Na]+.
p-Tolyl
2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-6-O-p-me-
(1!3)-4,6-O-benzylidene-2-deoxy-2-N-
thoxybenzyl-b-d-glucopyranosyl-
AHCTREUNG
phthalimido-1-thio-b-d-glucopyranoside (14b): The mixture of donor 11
(714 mg, 1 mmol) and freshly activated MS 4 Š (800 mg) in diethyl ether
(20 mL) was stirred for 1 h at room temperature, and cooled down to
ꢀ658C followed by the addition of AgOTf (771 mg, 3 mmol) in anhy-
drous Et2O (10 mL) directly to the solution without touching the wall of
the reaction flask. After 5 min, p-TolSCl (157 mL, 1 mmol) was added via
a syringe to activate the donor. The yellow color of the reaction disap-
peared quickly and TLC analysis showed the donor was completely con-
sumed. A solution of acceptor 2 (451 mg, 0.9 mmol) and TTBP (248 mg,
1 mmol) in CH2Cl2 (3 mL) was then slowly added to the reaction mixture
along the wall of the reaction flask. It was stirred for 90 min until the
temperature reached 08C, and triethylamine (300 mL) was added. The re-
action mixture was concentrated to remove most Et2O, re-suspended in
CH2Cl2 (100 mL), and filtered. The filtrate was concentrated and purified
by flash column chromatography using a three solvent system (CH2Cl2,
hexanes and EtOAc) to give the desired disaccharide 14b (740 mg,
0.675 mmol, 75%). 1H NMR (400 MHz, CDCl3): d=ꢀ0.16 (s, 3H,
CH3Si), ꢀ0.09 (s, 3H, CH3Si), 0.74 (s, 9H, (CH3)3CSi), 2.28 (s, 3H, p-
Sodium methoxide in MeOH (5m, 4 mL) was added at room temperature
to
a solution of p-tolyl-2-deoxy-2-azido-3,4,6-tri-O-acetyl-1-thio-a/b-d-
glucopyranoside (6.0 g, 13.7 mmol) in MeOH (20 mL). After 2 d, the sol-
ution was neutralized with Amberlite IR-120, filtered and evaporated.
The crude mixture of p-tolyl 2-deoxy-2-azido-1-thio-d-glucopyranosides
obtained was azotropically dried with anhydrous toluene and then dis-
solved in anhydrous CH3CN (30 mL). Benzaldehyde dimethyl acetal
(4.2 mL, 27.4 mmol) and camphorsulfonic acid (0.9 g, 4.1 mmol) were
added and the reaction mixture was stirred at room temperature over-
night. The reaction was quenched with Et3N and evaporated. Silica gel
column chromatography (hexanes/EtOAc 3:1) afforded compound 10
(3.2 g) and the corresponding b-isomer (1.6 g) in 90% total yield.
1H NMR (400 MHz, CDCl3): d = 2.37 (s, 3H), 2.88 (brs, 1H, OH), 3.60
(t, 3J
A
ACHTREUNG
CH3ArS), 3.12 (m, 1H), 3.29 (m, 1H), 3.38 (t, 3J
3.42 (dd, 3J
(H,H)=2.0, 8.4 Hz, 1H), 3.57–3.67 (m, 3H), 3.83 (s, 3H, p-
CH3OAr), 3.87 (t, 3J
(H,H)=8.8 Hz, 1H), 4.28–4.44 (m, 5H), 4.58 (d, J=
12 Hz, 1H), 4.66 (t, 3J(H,H)=8.8 Hz, 1H), 4.73 (d, 3J
(H,H)=8.4 Hz,
1H), 5.03 (t, 3J
(H,H)=8.4 Hz, 1H), 5.33 (s, 3H, PhCH), 5.44 (d,
3J(H,H)=10.8 Hz, 1H), 6.90–7.95 (m, 27H); 13C NMR (100 MHz,
A
3J
3J
3J
A
ACHTREUNG
3
ACHTREUNG
AHCTREUNG
(H,H)=5.0, 10.2 Hz, 1H), 4.44 (dt, J
AHCTREUNG
ACHTREUNG
A
ACHTREUNG
(50 MHz, CDCl3): d = 21.2, 63.3, 63.9, 68.5, 70.7, 81.7, 88.1, 102.2, 126.3,
128.4, 129.0, 129.5, 130.0, 133.1, 136.8, 138.5; ESI-MS: m/z: calcd for
C20H21N3NaO4S: 422.1, found: 422.2 [M+Na]+.
AHCTREUNG
AHCTREUNG
CDCl3): d=ꢀ4.7, ꢀ3.7, 18.2, 21.4, 26.1, 54.7, 55.6, 68.7, 70.8, 71.0, 73.1,
74.4, 74.6, 76.2, 76.5, 81.2, 83.4, 84.7, 99.6, 101.6, 114.0, 126.7–138.5 (aro-
matic carbons), 159.5, 164.7 (carbonyl groups); HRMS: m/z: calcd for
C62H67NNaO13SSi: 1116.4000, found: 1116.3998 [M+Na]+.
p-Tolyl 2-O-benzoyl-3-O-benzyl-6-O-p-methoxybenzyl-1-thio-b-d-gluco-
pyranoside (17): Acetal 8 (6.5 g, 10.8 mmol) in anhydrous DMF (80 mL)
was cooled down to 08C followed by sequential addition of solid
NaCNBH3 (5.44 g, 86.4 mmol) and TFA (12.4 g, 108 mmol). The resulting
suspension was stirred for 48 h until no starting material was found.
After neutralization by solid NaHCO3, the solution was filtered and di-
p-Tolyl
thoxybenzyl-a-d-glucopyranosyl-
phthalimido-1-thio-b-d-glucopyranoside (14a): When acceptor
2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-6-O-p-me-
(1!3)-4,6-O-benzylidene-2-deoxy-2-N-
was
AHCTREUNG
2
luted with EtOAc followed by washing with
a saturated aqueous
added as a solution in diethyl ether, 14a (~5%) was separated from the
reaction along with 14b (75%). 1H NMR (600 MHz, CDCl3): d=ꢀ0.20
(s, 3H, CH3Si), ꢀ0.14 (s, 3H, CH3Si), 0.70 (s, 9H, (CH3)3CSi), 2.30 (s, 3H,
NaHCO3 solution. The organic phase was collected and applied to flash
column to afford alcohol 17 (6.1 g, 95%) containing trace amount of re-
gioisomer p-tolyl 2-O-benzoyl-3-O-benzyl-4-O-p-methoxybenzyl-1-thio-b-
d-glucopyranoside. Pure 17 was obtained after removal of TBS from
compound 11 following the general procedure for TBS deprotection.
1H NMR (400 MHz, CDCl3): d=2.31 (s, 3H, CH3), 3.52–3.60 (m, 1H),
3
3
ACHTREUNG
p-CH3ArS), 2.74 (dd, J
A
10.8 Hz, 1H), 3.04–3.08 (m, 1H), 3.54–3.62 (m, 2H), 3.66 (t, 3J
9.0 Hz, 1H), 3.74 (dd, 3J
CH3OAr), 4.21 (dd, 3J
(t, 3J
4.69 (d, J
(dd, 3J(H,H)=4.2, 9.6 Hz, 1H), 5.48 (d, 3J
3J(H,H)=10.8 Hz, 1H), 6.90–7.92 (m, 27H); 13C NMR (100 MHz,
ACHTREUNG
AHCTREUNG
3.69 (t, 3J
ACHTREUNG
AHCTREUNG
4.49 (d, 3J
G
ACHTREUNG
A
ACHTREUNG
3
3
ACHTREUNG
3J
3J
A
ACHTREUNG
A
(H,H)=9.0, 9.6 Hz, 1H), 5.09
3
ACHTREUNG
A
ACHTREUNG
A
18H); 13C NMR (100 MHz, CDCl3): d=21.4, 55.5, 70.4, 72.3, 72.4, 73.7,
74.9, 78.5, 83.9, 86.9, 114.1, 128.0–138.3 (aromatic carbons), 159.6, 165.4
(carbonyl groups); ESI-MS: m/z: calcd for C35H36NaO7S: 623.2, found:
623.3 [M+Na]+.
AHCTREUNG
CDCl3): d=ꢀ5.1, ꢀ3.5, 18.2, 21.4, 26.3, 54.5, 55.6, 67.2, 68.6, 73.1, 73.1,
73.2, 74.0, 75.0, 79.7, 83.0, 85.1, 96.8, 101.3, 113.9, 123.7, 124.2, 126.2–
138.7 (aromatic carbons), 159.3, 164.9, 167.4; ESI-MS: m/z: calcd for
C62H67NNaO13SSi: 1116.4, found: 1116.2 [M+Na]+.
p-Tolyl
2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-6-O-p-me-
Methyl
2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-6-O-p-me-
thoxybenzyl-1-thio-b-d-glucopyranoside (11): A solution of alcohol 17
(5.56 g, 9.26 mmol) in anhydrous CH2Cl2 (50 mL) was cooled down to
ꢀ208C followed by sequential addition of 2,6-lutidine (1.98 g, 18.5 mmol)
and TBSOTf (3.67 g, 13.9 mmol). The resulting solution was warmed to
room temperature slowly until no starting material was left judged by
TLC. The reaction mixture was diluted with CH2Cl2 (50 mL) and washed
with saturated NaHCO3 solution. The organic phase was collected and
thoxybenzyl-b-d-glucopyranosyl-
(1!3)-4,6-O-benzylidene-2-deoxy-2-N-
phthalimido-1-thio-b-d-glucopyranoside (15): The mixture of donor 7
(714 mg, 1 mmol), acceptor 10 (370 mg, 0.9 mmol) and freshly activated
MS 4 Š (800 mg) in diethyl ether (20 mL) and CH2Cl2 (10 mL) was stir-
red for 1 h at room temperature, and cooled down to ꢀ658C. A solution
of AgOTf (771 mg, 3 mmol) in anhydrous Et2O (10 mL) was added di-
536
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 529 –540

Oligosaccharides
FULL PAPER
rectly to the solution without touching the wall of the reaction flask.
After 10 min, p-TolSCl (157 mL, 1 mmol) was added via a syringe. The re-
action mixture was stirred for 1.5 h until the temperature reached 08C,
and triethylamine (300 mL) was added. The reaction mixture was concen-
trated to remove most Et2O, resuspended in CH2Cl2 (100 mL), and fil-
tered. The filtrate was concentrated and purified by flash column chro-
matography (hexanes/EtOAc 4:1 ! 2.5:1) to give the desired disacchar-
ide 15 (800 mg, 0.792 mmol, 88%). 1H NMR (400 MHz, CDCl3): d=
5.28 (m, 2H), 6.84–8.06 (m, 33H); ESIMS: m/z: calcd for
C75H79NNaO19Si: 1348.5, found: 1348.6 [M+Na]+.
Method2 : Tetrasaccharide 19 (948 mg, 0.51 mmol) was synthesized in
64–75% yield using building blocks 11 (540 mg, 0.75 mmol), 2 (342 mg,
0.68 mmol), and 22 (870 mg, 0.68 mmol) following protocol A for one-pot
synthesis. 1H NMR (400 MHz, CDCl3): d=ꢀ0.18 (s, 3H, CH3Si), ꢀ0.12
(s, 3H, CH3Si), 0.73 (s, 9H, (CH3)3CSi), 2.64 (m, 1H), 2.73 (m, 1H), 2.92
(m, 1H), 3.06 (m, 1H), 3.15 (m, 1H), 3.26–3.33 (m, 2H), 3.31 (s, 3H,
ꢀ0.16 (s, 3H, CH3Si), ꢀ0.08 (s, 3H, CH3Si), 0.75 (s, 9H, (CH3)3CSi), 3.07
CH3O), 3.38–3.43 (m, 3H), 4.38 (m, 1H), 3.55 (t, 3J
3.60–3.65 (m, 2H), 3.75 (s, 3H, CH3O), 3.78 (s, 3H, CH3O), 3.91–3.95 (m,
2H), 4.02 (d, 3J
(H,H)=12 Hz, 1H), 4.17–4.43 (m, 9H), 4.50–4.59 (m,
3H), 4.64 (m, 2H), 4.88 (m, 3H), 4.98 (s, 1H, PhCH), 5.19 (d, 3J
(H,H)=
A
3
(m, 1H), 3.29 (dd, J
N
3.44 (m, 2H), 3.56–3.61 (m, 2H), 3.68 (t, 3J
AHCTREUNG
p-CH3OAr), 3.87 (m, 1H), 4.27–4.33 (m, 4H), 4.35 (d, 3J
ACHTREUNG
1H), 4.44 (d, 3J
(H,H)=11.2 Hz, 1H), 5.58 (d, 3J
8.4 Hz, 1H), 5.23 (s, 1H, PhCH), 6.79–7.82 (m, 46H); 13C NMR
(100 MHz, CDCl3): d=ꢀ4.7, ꢀ3.7, 18.1, 26.0, 55.2, 55.5, 55.50, 55.51,
56.1, 57.0, 66.2, 66.4, 66.8, 68.7, 68.9, 71.0, 72.2, 73.1, 73.9, 73.9, 74.1, 74.4,
74.5, 75.2, 75.4, 76.0, 76.1, 80.9, 81.3, 81.6, 83.4, 97.6, 99.4, 99.7, 100.4,
101.4, 101.6, 113.9–138.7 (aromatic carbons), 159.5, 159.4, 164.5, 164.7
(carbonyl groups); HRMS: m/z: calcd for C105H108N2NaO27Si: 1879.6806,
found: 1879.6783 [M+Na]+.
3
4.67 (dd, J
(H,H)=8.4, 10.0 Hz, 1H), 4.73 (d, J
(d, 3J
(H,H)=8.4 Hz, 1H), 5.04 (t, 3J
PhCH), 6.91–7.46 (m, 23H); 13C NMR (100 MHz, CDCl3): d=ꢀ4.7,
ꢀ3.7, 18.1, 21.4, 26.1, 55.4, 55.5, 57.1, 66.7, 68.6, 68.9, 70.9, 73.0, 74.5, 74.6,
75.6, 76.1, 81.8, 83.4, 99.7, 99.7, 101.6, 114.0, 126.7–138.0 (aromatic car-
bons), 159.5, 164.7 (carbonyl groups); HRMS: m/z: calcd for
C56H63NNaO14Si: 1024.3916, found: 1024.3879 [M+Na]+.
p-Tolyl 2-O-benzoyl-3-O-benzyl-6-O-p-methoxybenzyl-b-d-glucopyrano-
p-Tolyl
thoxybenzyl-b-d-glucopyranosyl-
benzylidene-b-d-glucopyranosyl-
(1!4)-2-O-benzoyl-3-O-benzyl-6-O-p-
2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-6-O-p-me-
syl-
G
AHCTREUNG
pyranoside (21): Compound 21 was synthesized in 92% yield from com-
pound 14b following the general procedure for TBS removal. 1H NMR
(400 MHz, CDCl3): d=2.28 (s, 3H, p-CH3ArS), 2.70 (d, J=2.4 Hz, 1H),
3.06 (m, 1H), 3.37–3.46 (m, 3H), 3.64–3.68 (m, 2H), 3.68–3.85 (m, 2H),
AHCTREUNG
methoxybenzyl-b-d-glucopyranoside (18): Compound 18 (100 mg, 50%)
was synthesized using donor 14b and acceptor 17 following the general
procedure for single-step pre-activation based glycosylation. 1H NMR
(400 MHz, CDCl3): d=ꢀ0.16 (s, 3H, CH3Si), ꢀ0.11 (s, 3H, CH3Si), 0.73
(s, 9H, (CH3)3CSi), 2.23 (s, 3H, CH3), 3.10 (m, 1H), 3.16-.20 (m, 2H),
3.27–3.32 (m, 2H), 3.35–3.45 (m, 4H), 3.56–3.68 (m, 3H), 3.75 (s, 3H,
OCH3), 3.78 (s, 3H, OCH3), 3.81 (m, 1H), 3.99–4.21 (m, 2H), 4.18 (d,
3.82 (s, 3H, p-CH3OAr), 4.31–4.38 (m, 4H), 4.44 (d, 3J
1H), 4.50 (d, J
9.6 Hz, 1H), 5.44 (s, 1H, PhCH), 5.44 (d, 3J
7.81 (m, 27H); 13C NMR (100 MHz, CDCl3): d=21.4, 54.5, 55.6, 68.9,
70.4, 70.7, 72.8, 73.2, 73.5, 73.8, 74.2, 81.4, 82.4, 84.7, 100.3, 101.8, 114.1,
126.5–138.6 (aromatic carbons), 159.6, 164.7 (carbonyl groups); HRMS:
m/z: calcd for C56H53NNaO13S: 1002.3135, found: 1002.3140 [M+Na]+.
3J
2H), 4.35 (d, 3J
4.98 (d, 3J(H,H)=8.4 Hz, 1H), 4.57 (d, 3J
3J(H,H)=11.6 Hz, 1H), 4.67 (dd, 3J
(H,H)=8.8, 9.2 Hz, 1H), 4.74 (d, J=
8.0 Hz, 1H), 4.83 (d, 3J(H,H)=12 Hz, 1H), 5.03 (t, 3J
(H,H)=8.8 Hz,
1H), 5.10 (t, 3J(H,H)=9.2 Hz, 1H), 5.25 (d, 3J
(H,H)=8.4 Hz, 1H), 5.29
A
ACHTREUNG
A
ACHTREUNG
A
ACHTREUNG
Methyl 2-O-benzoyl-3-O-benzyl-6-O-p-methoxybenzyl-b-d-glucopyrano-
A
ACHTREUNG
syl-
G
A
ACHTREUNG
pyranoside (22): Compound 22 (500 mg) was synthesized in 87% yield
from compound 15 following the general procedure for TBS removal.
A
ACHTREUNG
(s, 1H, PhCH), 6.78–7.94 (m, 37H); 13C NMR (100 MHz, CDCl3): d=
ꢀ4.7, ꢀ3.7, 18.1, 21.4, 26.0, 55.5, 56.1, 66.4, 68.0, 68.7, 68.8, 71.0, 72.1,
72.6, 73.1, 74.4, 74.5, 74.8, 75.5, 75.7, 76.1, 79.0, 81.4, 81.9, 83.4, 86.2, 97.9,
99.6, 101.4, 113.9–138.5 (aromatic carbons), 159.3, 159.5, 164.7, 165.3 (car-
bonyl groups); ESI-MS: m/z: calcd for C90H95NNaO20SSi: 1592.6, found:
1592.7 [M+Na]+.
1H NMR (400 MHz, CDCl3): d=2.70 (d, 3J
(H,H)=2.4 Hz, 1H), 3.13 (m,
1H), 3.35 (s, 3H, CH3O), 3.39–3.51 (m, 3H), 3.56- 3.71 (m, 2H), 3.78
3
ꢀ3.88 (m, 2H), 3.82 (s, 3H, p-CH3OAr), 4.27 (dd, J
A
1H), 4.30–4.34 (m, 3H, 1H), 4.45 (d, 3J
G
3
3
ACHTREUNG
3J
A
G
9.6 Hz, 1H), 5.00 (t, 3J
A
Methyl
thoxybenzyl-b-d-glucopyranosyl-
phthalimido-b-d-glucopyranosyl-
2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-6-O-p-me-
1H), 5.45 (s, 1H), 6.88–7.47 (m, 23H); 13C NMR (100 MHz, CDCl3): d=
55.2, 55.5, 57.1, 66.5, 69.0, 70.4, 72.8, 73.1, 73.5, 73.8, 74.2, 76.1, 81.7, 82.4,
99.7, 100.3, 101.8, 114.1, 126.5–138.2 (aromatic carbons), 159.6, 164.7 (car-
bonyl groups); HRMS: m/z: calcd for C50H49NNaO14: 910.3051, found:
910.3055 [M+Na]+.
AHCTREUNG
A
methoxybenzyl-b-d-glucopyranosyl-(1!3)-2-deoxy-4,6-O-benzylidene-2-
N-phthalimido-b-d-glucopyranoside (19)
Tetrasaccharide 19 was synthesized by two methods.
p-Tolyl
thoxybenzyl-b-d-glucopyranosyl-
benzylidene-b-d-glucopyranosyl-
(1!4)-2-O-benzoyl-3-O-benzyl-6-O-p-
2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-6-O-p-me-
Method1 : A mixture of donor 18 (100 mg, 0.063 mmol), acceptor 6
(28 mg, 0.056 mmol) and freshly activated MS 4 Š (200 mg) in diethyl
ether (3 mL) and CH2Cl2 (3 mL) was stirred for 1 h at room temperature,
and cooled down to ꢀ658C. A solution of AgOTf (45 mg, 0.18 mmol) in
anhydrous Et2O (1 mL) was added directly to the solution without touch-
ing the wall of the reaction flask. After 10 min, p-TolSCl (9 mL, 1 equiv)
was added via a syringe. The reaction mixture was stirred for 1.5 h until
the temperature reached 08C, and triethylamine (100 mL) was added. It
was concentrated to remove most Et2O, resuspended in CH2Cl2 (20 mL),
and filtered. The filtrate was concentrated and purified by flash column
AHCTREUNG
AHCTREUNG
methoxybenzyl-b-d-glucopyranosyl-(1!3)-2-deoxy-2-N-phthalimido-3,6-
O-benzylidene-b-d-glucopyranoside (23): Compound 23 (50 mg) was syn-
thesized in 75% yield using donor 14b and acceptor 21 following the
general procedure for single-step pre-activation based glycosylation.
1H NMR (600 MHz, CDCl3): d=ꢀ0.19 (s, 3H, CH3Si), ꢀ0.14 (s, 3H,
CH3Si), 0.71 (s, 9H, (CH3)3CSi), 2.23 (s, 3H, CH3), 2.60 (m, 1H), 2.71 (m,
1H), 2.91 (m, 1H), 3.04 (m, 1H), 3.12 (m, 1H), 3.23 (m, 2H), 3.32–3.41
(m, 3H), 3.49–3.62 (m, 4H), 3.70 (m, 1H), 3.71 (s, 3H, OCH3), 3.76 (s,
3H, OCH3), 3.89–3.92 (m, 2H), 4.01 (m, 1H), 4.15–4.21 (m, 3H), 4.24–
chromatography (hexanes/EtOAc/CH2Cl2 4:1:1
!
2:1:1) to give 19
(49 mg, 0.026 mmol, 47%), along with small amount of trisaccharide 20.
4.28 (m, 2H), 4.32 (d, 3J
4.56 (m, 3H), 4.63 (d, 3J(H,H)=11.4 Hz, 1H), 4.67 (d, 3J
1H), 4.85 (t, 3J(H,H)=8.4 Hz, 1H), 4.95 (t, 3J
(H,H)=7.8 Hz, 1H), 4.96
(s, 1H, PhCH), 5.16 (d, 3J
(H,H)=9.0 Hz, 1H), 5.21 (s, 1H, PhCH), 5.35
ACHTREUNG
Compound 20: 1H NMR (400 MHz, CDCl3): d=ꢀ0.16 (s, 3H, CH3Si),
A
ACHTREUNG
ꢀ0.09 (s, 3H, CH3Si), 0.74 (s, 9H, (CH3)3CSi), 3.02–3.08 (m, 1H), 3.22–
3
A
ACHTREUNG
3.76 (m, 10H), 3.78 (s, 3H, CH3O), 4.00–4.04 (m, 2H), 4.21 (d, J
A
5.2 Hz, 1H), 4.27 (d, 3J
(H,H)=12 Hz, 1H), 4.33 (dd, 3J
ACHTREUNG
AHCTREUNG
(d, J=10.2 Hz, 1H), 6.78–7.82 (m, 50H); 13C NMR (100 MHz, CDCl3):
d=ꢀ4.7, ꢀ3.6, 18.1, 21.4, 26.0, 54.4, 55.5, 55.5, 56.1, 66.2, 66.8, 68.6, 68.7,
68.8, 70.5, 71.0, 72.2, 73.1, 73.9, 74.0, 74.0, 74.4, 75.1, 75.4, 76.0, 76.8, 77.0,
80.8, 81.3, 83.4, 84.6, 97.5, 99.4, 100.3, 101.3, 101.6, 113.9–138.6 (aromatic
3
3
ACHTREUNG
10.0 Hz, 1H), 4.35 (d, J
A
3
3
ACHTREUNG
1H), 4.52 (dd, J
4.60 (d, 3J(H,H)=12 Hz, 1H), 4.69 (d, 3J
3J
A
A
ACHTREUNG
A
ACHTREUNG
Chem. Eur. J. 2007, 13, 529 –540
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
537

X. Huang and L. Huang
carbons), 159.4, 159.4, 164.5, 164.7 (carbonyl groups); ESI-MS: m/z:
calcd for C111H112N2NaO26SSi: 1973.3, found: 1973.0 [M+Na]+.
(m, 2H), 3.42 (m, 2H), 3.47 (m, 1H), 3.55–3.60 (m, 2H), 3.63–3.66 (m,
2H), 3.69 (s, 3H, p-CH3OPh), 3.72 (s, 3H, p-CH3OPh), 3.74 (s, 3H, p-
CH3OPh), 3.78 (t, 3J
ACHTREUNG
Methyl 4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-2-deoxy-2-N-phtha-
limido-b-d-glucopyranosyl-(1!4)-2-O-benzoyl-3-O-benzyl-6-O-p-me-
3J
A
ACHTREUNG
ACHTREUNG
thoxybenzyl-b-d-glucopyranosyl-
G
AHCTREUNG
phthalimido-b-d-glucopyranosyl-
(1!4)-2-O-benzoyl-3-O-benzyl-6-O-p-
AHCTREUNG
methoxybenzyl-b-d-glucopyranosyl-(1!3)-4,6-O-benzylidene-2-deoxy-2-
N-phthalimido-b-d-glucopyranoside (28): Pentasaccharide 28 (350 mg,
0.156 mmol) was synthesized in 65% yield using building blocks 26
(154 mg, 0.25 mmol), 21 (220 mg, 0.22 mmol), and 22 (200 mg,
PhCH), 5.11 (d, J=8.4 Hz, 1H), 5.14 (d, J=8.4 Hz, 1H), 5.30 (s, 1H,
PhCH), 6.80–7.82 (m, 69H, ArH); 13C NMR (100 MHz, CDCl3): d=
ꢀ4.8, ꢀ3.7, 18.1, 26.0, 55.1, 55.4, 55.5, 57.0, 65.9, 66.2, 66.4, 68.6, 68.8,
71.0, 72.2, 72.3, 73.1, 73.8, 73.9, 74.0, 74.1, 74.3, 74.5, 75.0, 75.1, 75.4, 75.8,
75.9, 76.1, 76.7, 76.8, 80.8, 81.3, 81.4, 81.5, 83.4, 97.4, 97.5, 99.4, 99.7,
100.2, 100.3, 101.4, 101.4, 101.6, 113.9–138.6 (aromatic carbons), 159.4,
159.5, 164.4, 164.6 (carbonyl groups); HRMS: m/z: calcd for
0.22 mmol) following protocol
A
for one-pot synthesis. 1H NMR
(400 MHz, CDCl3): d=ꢀ0.31 (s, 3H, CH3Si), ꢀ0.16 (s, 3H, CH3Si), 0.54
(s, 9H, (CH3)3CSi), 2.61–2.70 (m, 3H), 2.88–2.94 (m, 2H), 3.09 (d,
3J
ACHTREUNG
C
154H153N3NaO40Si: 2734.9697, found: 2734.9697 [M+Na]+.
3
CH3OPh), 3.92–4.15 (m, 9H), 4.24 (dd, J(H,H)=4.8, 10.4 Hz, 1H), 4.25–
A
Methyl 2-O-benzoyl-3-O-benzyl-6-O-p-methoxybenzyl-b-d-glucopyrano-
syl-(1!3)-4,6-O-benzylidene-2-deoxy-2-N-phthalimido-b-d-glucopyrano-
4.31 (m, 4H), 4.41–4.56 (m, 6H), 4.65–4.77 (m, 4H), 4.95 (d, 3J
8.4 Hz, 1H), 5.08 (s, 3H, PhCH), 5.09 (s, 3H, PhCH), 5.15 (d, 3J
ACHTREUNG
AHCTREUNG
syl-
nosyl-
nosyl-
(1!4)-2-O-benzoyl-3-O-benzyl-6-O-p-methoxybenzyl-b-d-glucopyra-
8.8 Hz, 1H), 5.22 (d, 3J
(H,H)=8.4 Hz, 1H), 5.41 (s, 1H, PhCH), 6.89–
A
N
7.93 (m, 51H, ArH); 13C NMR (100 MHz, CDCl3): d=ꢀ5.1, ꢀ4.2, 17.8,
25.4, 55.2, 55.4 (3C), 55.7, 56.9, 58.4, 66.0, 66.1, 66.3, 67.1, 67.4, 68.7 (2C),
68.8, 69.6, 72.2, 72.4, 73.5, 74.0, 74.2, 74.3, 74.3, 74.7, 75.0, 76.1, 76.3, 80.5,
80.6, 81.5, 81.6, 82.8, 97.4, 97.6, 99.6, 100.2, 100.3, 101.6 (2C), 102.0,
113.9–138.5 (aromatic carbons), 159.5, 159.5, 164.6 (carbonyl groups);
HRMS: m/z: calcd for C126H125N3NaO33Si: 2258.7862, found: 2258.7900
[M+Na]+.
(1!4)-2-O-benzoyl-3-O-benzyl-6-O-p-methoxybenzyl-b-d-gluco-
pyranosyl-(1!3)-3,6-O-benzylidene-2-deoxy-2-N-phthalimido-b-d-gluco-
pyranoside (31): Compound 31 was obtained from compound 30 in 90%
yield following the general procedure for TBS removal. 1H NMR
3
(600 MHz, CDCl3): d=2.59–2.69 (m, 5H), 2.87 (d, J
N
3
2.92 (d, J
3J
(H,H)=10.2 Hz, 1H), 3.28–3.37 (m, 8H), 3.43–3.47 (m, 3H), 3.58–3.63
(m, 7H), 3.65 (s, 3H, OCH3), 3.73 (s, 3H, OCH3), 3.82 (s, 3H, OCH3),
3.83–3.91 (m, 4H), 3.96 (d, 3J
(H,H)=12 Hz, 1H), 4.03–4.21 (m, 8H),
(H,H)=12 Hz, 1H), 4.47 (t, 3J
(H,H)=
(H,H)=8.4 Hz, 1H), 4.84 (d,
(H,H)=10.2 Hz, 1H), 3.01–3.04 (m, 2H), 3.10 (m, 1H), 3.17 (t,
AHCTREUNG
Methyl
thoxybenzyl-b-d-glucopyranosyl-
phthalimido-b-d-glucopyranosyl-(1!4)-2-O-benzoyl-3-O-benzyl-6-O-p-
methoxybenzyl-b-d-glucopyranosyl-
(1!3)-4,6-O-benzylidene-2-deoxy-2-
N-phthalimido-b-d-glucopyranosyl-
(1!4)-2-O-benzoyl-3-O-benzyl-6-O-
2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-6-O-p-me-
AHCTREUNG
AHCTREUNG
4.27–4.40 (m, 8H), 4.45 (d, 3J
E
10.2 Hz, 1H), 4.50–4.61 (m, 4H), 4.81 (t, 3J
ACHTREUNG
AHCTREUNG
3J
(H,H)=8.4 Hz, 1H), 4.86 (d, J
5.09 (s, 1H, PhCH), 5.11 (s, 1H, PhCH), 5.25 (s, 1H, PhCH), 5.35 (d,
3J(H,H)=10.2 Hz, 1H), 6.78–7.82 (m, 69H); 13C NMR (100 MHz,
CDCl3): d=55.1, 55.4, 55.46, 55.48, 55.8, 55.9, 57.1, 60.6, 64.6, 65.9, 66.0,
66.3, 66.7, 67.1, 68.6, 68.8, 70.5, 72.1, 72.3, 72.8, 72.9, 73.5, 73.6, 73.7, 73.8,
73.8, 74.0, 74.2, 74.9, 75.1, 75.7, 75.8, 75.9, 80.7, 80.7, 81.3, 81.4, 81.5, 82.3,
97.3, 97.5, 99.6, 100.0, 100.2, 100.3, 101.4, 101.5, 101.6, 113.9–138.6 (aro-
matic carbons), 159.37, 159.39, 159.6, 164.5, 164.6 (carbonyl groups); ESI-
MS: m/z: calcd for C148H139N3NaO40: 2622.6, found: 2622.7 [M+Na]+.
(H,H)=9.0 Hz, 1H), 4.90–4.94 (m, 3H),
3
AHCTREUNG
p-methoxybenzyl-b-d-glucopyranoside (29): Pentasaccharide 29 (224 mg,
0.096 mmol) was synthesized in 55% yield using building blocks 11
(156 mg, 0.218 mmol), 2 (99 mg, 0.196 mmol), 21 (173 mg, 0.176 mmol)
and 27 (87 mg, 0.176 mmol) following protocol B for one-pot synthesis.
1H NMR (600 MHz, CD2Cl2): d=ꢀ0.14 (s, 3H, CH3Si), ꢀ0.07 (s, 3H,
CH3Si), 0.76 (s, 9H, (CH3)3CSi), 2.63 (m, 1H), 2.74 (m, 1H), 2.98 (m,
1H), 3.03–3.05 (m, 2H), 3.09 (m, 1H), 3.17–3.22 (m, 2H), 3.29–3.45 (m,
AHCTREUNG
7H), 3.39 (s, 3H), 3.58 (t, 3J
9.0 Hz, 1H), 3.72 (s, 3H, p-CH3OPh), 3.73 (s, 3H, p-CH3OPh), 3.75 (s,
3H, p-CH3OPh), 3.80–3.83 (m, 2H), 3.91 (dd, 3J
(H,H)=4.8, 10.8 Hz,
1H), 3.98 (t, 3J(H,H)=10.8 Hz, 1H), 4.03 (dd, 3J
(H,H)=4.8, 10.8 Hz,
1H), 4.08 (d, 3J
(H,H)=7.8 Hz, 1H), 4.13–4.20 (m, 5H), 4.30–4.34 (m,
4H), 4.43 (d, 3J(H,H)=7.8 Hz, 1H), 4.45 (d, 3J
(H,H)=10.8 Hz, 1H),
4.52–4.59 (m, 4H), 4.68–4.75 (m, 5H), 4.85–4.87 (m, 2H), 5.07 (s, 1H,
PhCH), 5.17 (d, 3J(H,H)=8.4 Hz, 1H), 5.25 (d, 3J
(H,H)=8.4 Hz, 1H),
A
A
Methyl 2-O-acetyl-3-O-benzyl-6-O-p-methoxybenzyl-b-d-glucopyranosyl-
AHCTREUNG
(1!3)-2-deoxy-2-N-acetyl-4,6-O-benzylidene-b-d-glucopyranosyl-
2-O-acetyl-3-O-benzyl-6-O-p-methoxybenzyl-b-d-glucopyranosyl-
(1!3)-
2-deoxy-2-N-acetyl-4,6-O-benzylidene-b-d-glucopyranosyl-
(1!4)-2-O-
G
ACHTREUNG
ACHTREUNG
R
ACHTREUNG
acetyl-3-O-benzyl-6-O-p-methoxybenzyl-b-d-glucopyranosyl-(1!3)-2-
deoxy-2-N-acetyl-3,6-O-benzylidene-b-d-glucopyranoside (34): Acetic an-
hydride (0.3 mL) and DMAP (50 mg) was added to a solution of com-
pound 31 (100 mg) in anhydrous pyridine (5 mL). The reaction mixture
was stirred for 1 h at room temperature, diluted with dichloromethane
and washed with aqueous solution of 1n HCl. The organic layer was
dried over Na2SO4 and the desired compound 32 (102 mg) was obtained
from flash chromatography (hexanes/EtOAc/CH2Cl2 1:1:1) in 100%
yield. A solution of compound 32 (50 mg) and ethylenediamine (0.5 mL)
in n-butanol (5 mL) was heated under reflux for 1.5 h until no starting
material was observed by TLC. The solution was dried under reduced
pressure followed by chromatography to afford free amine. The free
amine was dissolved in anhydrous pyridine (3 mL) followed by addition
of acetic anhydride (0.2 mL) and DMAP (100 mg). The reaction was stir-
red for 1 h and diluted with dichloromethane followed by extraction and
flash chromatography (CH2Cl2/MeOH 30:1) to provide the desired prod-
uct 34 (40 mg, 50%). 1H NMR (600 MHz, CD2Cl2): d=1.74 (s, 3H), 1.76
(s, 3H), 1.88 (s, 3H), 1.89 (s, 3H), 1.91 (s, 3H), 1.95 (s, 3H), 1.96 (s, 3H),
3.09 (m, 1H), 3.17–3.22 (m, 3H), 3.24–3.33 (m, 4H), 3.45 (s, 3H, OCH3),
U
ACHTREUNG
5.31 (s, 1H, PhCH), 6.81–7.85 (m, 60H, ArH); 13C NMR (150 MHz,
CD2Cl2): d=ꢀ3.8, ꢀ4.3, 18.0, 25.8, 55.4, 55.4, 55.9, 56.0, 56.9, 66.1, 66.3,
67.3, 68.1, 68.6, 69.0, 71.0, 72.3, 72.4, 73.1, 73.5, 74.1, 74.2, 74.3, 74.4, 74.5,
74.6, 74.8, 74.9, 75.5, 75.8, 76.1, 76.2, 80.5, 81.3, 81.5, 81.8, 82.7, 83.4, 97.3,
97.8, 99.4, 100.3, 101.4, 101.6, 104.6, 113.7–139.6 (aromatic carbons),
159.4, 159.5, 164.6, 164.7 (carbonyl groups); HRMS: m/z: calcd for
C
133H138N2NaO33Si: 2341.8849, found: 2341.8850 [M+Na]+.
Methyl 2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-6-O-p-me-
thoxybenzyl-b-d-glucopyranosyl-
(1!3)-4,6-O-benzylidene-2-deoxy-2-N-
phthalimido-b-d-glucopyranosyl-(1!4)-2-O-benzoyl-3-O-benzyl-6-O-p-
methoxybenzyl-b-d-glucopyranosyl-
(1!3)-4,6-O-benzylidene-2-deoxy-2-
N-phthalimido-b-d-glucopyranosyl-
(1!4)-2-O-benzoyl-3-O-benzyl-6-O-
AHCTREUNG
AHCTREUNG
AHCTREUNG
p-methoxybenzyl-b-d-glucopyranosyl-(1!3)-4,6-O-benzylidene-2-deoxy-
2-N-phthalimido-b-d-glucopyranoside (30): Hexasaccharide 30 (327 mg,
0.12 mmol) was synthesized in 54–60% yield using building blocks 11
(178 mg, 0.249 mmol), 2 (113 mg, 0.224 mmol), 21 (198 mg, 0.201 mmol)
and 22 (178 mg, 0.201 mmol) following protocol B for one-pot synthesis.
1H NMR (600 MHz, CDCl3): d=ꢀ0.17 (s, 3H, CH3Si), ꢀ0.08 (s, 3H,
3.37–3.49 (m, 8H), 3.52–3.57 (m, 4H), 3.65 (t, 3J
(H,H)=9.0 Hz, 1H),
3.69–3.71 (m, 3H), 3.75 (s, 3H, OCH3), 3.77 (s, 3H, OCH3), 3.78 (s, 3H,
OCH3), 3.86–3.97 (m, 4H), 4.09 (m, 1H), 4.22–4.29 (m, 4H), 4.36–4.39
(m, 2H), 4.43–4.50 (m, 6H), 4.54–4.57 (m, 4H), 4.65 (d, J
1H), 4.69–4.75 (m, 3H), 4.78–4.95 (m, 4H), 4.98 (t, 3J
G
CH3Si), 0.75 (s, 9H, (CH3)3CSi), 2.56–2.61 (m, 2H), 2.67 (dd, 3J
A
3.0, 10.2 Hz, 1H), 2.71 (dd, 3J
3J(H,H)=9.6 Hz, 1H), 2.95 (d, 3J
R
U
U
1H), 5.37 (s, 1H, PhCH), 5.40 (s, 1H, PhCH), 5.44 (s, 1H, PhCH), 6.81–
538
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 529 –540

Oligosaccharides
FULL PAPER
7.44 (m, 42H); ESI-MS: m/z: calcd for C117H136N3O38: 2190.9, found:
2190.3 [M+H]+.
103.3, 103.3, 174.38, 174.32, 174.9, 175.08, 175.08, 175.6 (carbonyl
groups); HRMS: m/z: calcd for C43H67N3NaO34
: 1192.3504, found:
1192.3550 [M+Na]+.
Methyl 2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-b-d-glucopyr-
Methyl (b-d-glucopyranosyluronic acid)-
G
anosyl-
anosyl-(1!4)-2-O-benzoyl-3-O-benzyl-b-d-glucopyranosyl-
benzylidene-2-deoxy-2-N-phthalimido-b-d-glucopyranosyl-
benzoyl-3-O-benzyl-b-d-glucopyranosyl-(1!3)-4,6-O-benzylidene-2-
deoxy-2-N-phthalimido-b-d-glucopyranoside (36): Compound 36 (103 mg,
0.437 mmol) was synthesized in 74% yield from compound 30 (160 mg,
ACHTREUNG
glucopyranoside) (39): Compound 39 (2.6 mg, 6 mmol) was obtained from
disaccharide 15 (13 mg, 14.6 mmol) following the general procedures for
deprotection and oxidation-state adjustment in 41% overall yield.
1H NMR (600 MHz, D2O): d=2.47 (s, 3H, AcNH), 3.80 (m, 1H), 3.91–
AHCTREUNG
AHCTREUNG
4.03 (m, 4H), 3.96 (s, 3H, OCH3), 4.18 (t, 3J
(dd, 3J
1.8, 12.6 Hz, 1H), 4.91 (d, 3J
1
A
0.059 mmol) following the general procedure for PMB removal. H NMR
H
(600 MHz, CDCl3): d=ꢀ0.19 (s, 3H, CH3Si), ꢀ0.07 (s, 3H, CH3Si), 0.77
7.8 Hz, 1H); HRMS: calcd for C15H25NNaO12: 434.1274, found:434.1266
(s, 9H, (CH3)3CSi), 2.67–2.72 (m, 2H), 2.85–2.86 (m, 2H), 3.03 (m, 1H),
[M+Na]+.
3.11–3.16 (m, 2H), 3.22 (t, 3J
(H,H)=10.2 Hz, 1H), 3.28 (s, 3H, OCH3),
N
3
ACHTREUNG
3.29–3.42 (m, 4H), 3.47–3.57 (m, 3H), 3.63 (t, J
(t, 3J(H,H)=9.0 Hz, 1H), 3.73–3.79 (m, 3H), 3.94 (dd, 3J
10.2 Hz, 1H), 4.01 (dd, 3J
(H,H)=4.8, 10.2 Hz, 1H), 4.03–4.08 (m, 1H),
4.14–4.18 (m, 1H), 4.28–4.37 (m, 4H), 4.42–4.50 (m, 3H), 4.5–4.65 (m,
4H), 4.83 (t, 3J(H,H)=8.4 Hz, 1H), 4.85 (t, 3J
(H,H)=9.0 Hz, 1H), 4.91
(d, 3J(H,H)=9.0 Hz, 1H), 4.97 (t, 3J
(H,H)=8.4 Hz, 1H), 5.08 (d,
3J(H,H)=8.4 Hz, 1H), 5.12 (d, 3J
(H,H)=8.4 Hz, 1H), 5.22 (s, 1H,
Methyl (b-d-glucopyranosyluronic acid)-
glucopyranosyl)-
C
G
ACHTREUNG
G
AHCTREUNG
2-N-acetyl-b-d-glucopyranoside (40): Compound 40 (32 mg, 39 mmol) was
obtained from tetrasaccharide 19 (210 mg, 0.112 mmol) following the
general procedures for deprotection and oxidation-state adjustment in
35% overall yield. 1H NMR (600 MHz, D2O): d=1.98 (s, 3H, AcNH),
1.99 (s, 3H, AcNH), 3.11–3.15 (m, 2H), 3.25–3.48 (m, 8H), 3.47 (s, 3H,
A
ACHTREUNG
A
ACHTREUNG
A
ACHTREUNG
CH3O), 3.48–3.63 (m, 8H), 4.68–4.71 (m, 2H), 4.24 (d, 3J
1H), 4.26 (d, 3J(H,H)=7.8 Hz, 2H), 4.33 (d, 3J
PhCH), 5.39 (s, 1H, PhCH), 5.41 (s, 1H, PhCH), 6.83–7.62 (m, 57H,
ArH); 13C NMR (100 MHz, CDCl3): d=ꢀ4.7, ꢀ3.8, 18.1, 26.0, 55.5, 56.1,
56.3, 57.1 (2C), 60.82, 60.83, 62.0, 66.1, 66.2, 66.5, 68.6, 68.7, 68.9, 70.6,
73.8 (2C), 74.2, 74.3, 74.5, 74.6, 74.7, 74.9, 75.3 (2C), 75.4, 75.6, 76.7, 80.7
(2C), 80.8, 83.3, 98.1 (2C), 99.76, 99.83, 100.0 (2C), 101.8, 101.9, 102.0,
123.6–138.4 (aromatic carbons), 164.8, 164.8, 164.4, 164.9 (carbonyl
groups); HRMS: m/z: calcd for C130H129N3NaO37Si: 2374.7972, found:
2374.7881 [M+Na]+.
N
13C NMR (150 MHz, D2O): d=22.3, 22.6, 54.3, 54.5, 57.2, 60.6, 60.8, 68.6,
68.7, 71.8, 72.5, 72.8, 73.7, 75.4, 75.45, 75.49, 75.9, 76.5, 80.1, 82.4, 83.1,
100.7, 101.9, 103.1, 103.2, 174.3, 174.9, 175.0, 175.6; HRMS: m/z: calcd
for C29H46N2NaO23: 813.2389, found: 813.2351 [M+Na]+.
Methyl (2-deoxy-2-N-acetyl-b-d-glucopyranosyl)-(1!4)-(b-d-glucopyra-
nosyluronic acid)-
A
4)-(b-d-glucopyranosyluronic acid)-(1!3)-(2-deoxy-2-N-acetyl-b-d-glu-
copyranoside) (41): Compound 41 (18 mg, 0.018 mmol) was obtained
from pentasaccharide 28 (130 mg, 0.058 mmol) following the general pro-
cedures for deprotection and oxidation-state adjustment in 31% overall
yield. 1H NMR (600 MHz, D2O): d=1.96 (s, 3H, AcNH), 1.97 (s, 3H,
AcNH), 1.99 (s, 3H, AcNH), 3.29–3.31 (m, 2H), 3.40–3.55 (m, 9H), 3.46
(s, 3H, CH3O), 3.65–3.72 (m, 10H), 3.78–3.80 (m, 2H), 3.86–3.88 (m,
Methyl (benzyl 2-O-benzoyl-3-O-benzyl-4-O-tert-butyldimethylsilyl-b-d-
glucopyranosyluronate)-
dene-b-d-glucopyranosyl)-(1!4)-(benzyl
glucopyranosyluronate)-
(1!3)-(4,6-O-benzylidene-2-deoxy-2-N-phthali-
mido-b-d-glucopyranosyl)-
(1!4)-(benzyl 2-O-benzoyl-3-O-benzyl-b-d-
ACHTREUNG
ACHTREUNG
AHCTREUNG
glucopyranosyluronate)-(1!3)-(2-deoxy-2-N-phthalimido-4,6-O-benzyli-
dene-b-d-glucopyranoside) (37): Compound 37 (238 mg, 0.089 mmol) was
synthesized in 82% yield from compound 36 (258 mg, 0.109 mmol) fol-
lowing the general procedure for oxidation and benzyl ester formation.
1H NMR (600 MHz, CD2Cl2): d=ꢀ0.14 (s, 3H, CH3Si), ꢀ0.26 (s, 3H,
3H), 4.39 (d, 3J
ACHTREUNG
3J(H,H)=8.4 Hz, 1H), 4.50 (d, 3J
A
ACHTREUNG
(150 MHz, D2O): d=22.3, 22.5, 22.6, 54.4, 54.5, 55.5, 57.2, 60.59, 60.60,
60.8, 68.45, 68.7, 69.8, 72.5, 72.6, 73.6, 73.7, 74.0, 75.4, 75.5, 76.0, 76.4,
76.5, 79.9, 80.1, 82.4, 82.6, 100.7, 100.8, 101.9, 103.23, 103.24, 173.3, 174.4,
174.9, 175.0, 175.1; HRMS: calcd for C37H59N3NaO28: 1016.3183, found:
1016.3179 [M+Na]+.
CH3Si), 0.72 (s, 9H, (CH3)3CSi), 3.04 (t, 3J
(H,H)=10.2 Hz, 1H), 3.11–
E
3.15 (m, 2H), 3.21–3.31 (m, 5H), 3.27 (s, 3H, OCH3), 3.38–3.47 (m, 6H),
3
3
ACHTREUNG
3.56–3.61 (m, 2H), 3.67 (t, J
10.2 Hz, 1H), 3.93–4.04 (m, 6H), 4.07–4.12 (m, 2H), 4.18 (dd, 3J
4.2, 9.6 Hz, 1H), 4.27–4.38 (m, 6H), 4.45 (d, 3J
(H,H)=12 Hz, 1H), 4.48
(dd, 3J
(H,H)=8.4, 10.2 Hz, 1H), 4.52–4.58 (m, 3H), 4.62–4.68 (m, 3H),
4.97 (d, 3J
(H,H)=8.4 Hz, 1H), 4.99 (s, 1H, PhCH), 5.01 (s, 1H, PhCH),
5.03 (d, 3J(H,H)=8.4 Hz, 1H), 5.10 (d, 3J
(H,H)=12 Hz, 1H), 5.12 (s,
1H, PhCH), 5.17 (d, 3J
(H,H)=12 Hz, 1H), 4.91–4.93 (m, 3H), 6.86–7.73
A
AHCTREUNG
Methyl (b-d-glucopyranosyluronic acid)-
glucopyranosyl)-(1!4)-(b-d-glucopyranosyluronic acid)-
2-N-acetyl-b-d-glucopyranosyl)-
(42): Compound 42 (21 mg, 0.021 mmol) was obtained from pentasac-
charide 29 (180 mg, 0.077 mmol) following the general procedures for de-
ACHTREUNG
AHCTREUNG
ACHTREUNG
(1!4)-(b-d-glucopyranosyluronic acid)
ACHTREUNG
A
ACHTREUNG
1
(m, 72H, ArH); 13C NMR (100 MHz, CD2Cl2): d=ꢀ5.2, ꢀ4.3, 17.9, 25.7,
53.6, 53.9, 54.1, 55.1, 55.6, 55.7, 57.0 (2C), 65.7, 65.9, 66.3, 67.28, 67.31,
68.2, 68.4, 68.5, 71.9, 72.9, 73.9, 72.2, 74.2, 74.6, 74.7, 75.8 (2C), 76.1, 77.0,
77.5, 79.8, 79.9, 80.7, 81.0, 81.152, 82.2, 98.2 (2C), 99.5, 99.6, 99.7, 99.8,
101.0, 101.1, 101.5, 123.2–138.3 (aromatic carbons), 164.5, 164.6, 164.6,
166.9, 166.9, 168.1 (carbonyl groups); HRMS: calcd for
protection and oxidation-state adjustment in 27% overall yield. H NMR
(600 MHz, D2O): d=1.97 (s, 3H, AcNH), 1.99 (s, 3H, AcNH), 3.26–3.31
(m, 3H), 3.43–3.57 (m, 8H), 3.36 (s, 3H, MeO), 3.65–3.74 (m, 9H), 3.75–
3.80 (m, 2H), 3.85–3.87 (m, 2H), 4.34 (d, 3J
ACHTREUNG
3J
A
ACHTREUNG
(150 MHz, D2O): d=22.43, 22.44, 54.3, 54.4, 57.6, 60.5, 68.2, 68.3, 71.2,
72.2, 72.4, 72.5, 73.3, 73.5, 73.7, 73.9, 74.2, 75.1, 75.4, 80.2, 80.3, 82.4, 82.7,
101.32, 101.32, 102.7, 102.9, 103.6, 171.11, 171.11, 172.6, 174.79, 174.84
(carbonyl groups); HRMS: m/z: calcd for C35H54N2NaO29: 989.2710,
found: 989.2687 [M+Na]+.
C
151H141N3NaO40Si: 2686.8758, found: 2686.8855 [M+Na]+.
Methyl (b-d-glucopyranosyluronic acid)-
(1!3)-(2-deoxy-2-N-acetyl-b-d-
glucopyranosyl)-(1!4)-(b-d-glucopyranosyluronic acid)-(1!3)-(2-deoxy-
2-N-acetyl-b-d-glucopyranosyl)-
(1!4)-(b-d-glucopyranosyluronic acid)-
AHCTREUNG
AHCTREUNG
AHCTREUNG
(1!3)-(2-deoxy-2-N-acetyl-b-d-glucopyranoside) (38): Compound 38
(27 mg, 0.023 mmol) was synthesized in 53% yield from compound 37
(102 mg, 0.043 mmol) following the general procedures for hydrogena-
tion, benzoyl/phthalimide removal and acetylation. 1H NMR (400 MHz,
D2O): d=2.01 (s, 3H, AcNH), 2.02 (s, 3H, AcNH), 2.03 (s, 3H, AcNH),
3.31–3.39 (m, 3H), 3.49–3.59 (m, 10H), 3.51 (s, 3H, MeO), 3.70–3.94 (m,
17H), 4.26 (d, 3J
3J(H,H)=8.4 Hz, 1H), 4.36 (d, 3J
N
Acknowledgements
G
ACHTREUNG
(100 MHz, D2O): d=22.4, 22.64, 22.64, 54.4, 54.4, 54.5, 57.3, 60.6, 60.7,
60.8, 68.6, 68.7, 68.8, 71.9, 72.6, 72.6, 72.9, 73.7, 73.8, 75.45, 75.49, 75.5,
75.9, 76.45, 76.54, 80.08, 80.14, 82.5, 82.6, 83.2, 100.7, 100.7, 101.9, 103.1,
We are grateful for financial supports from the University of Toledo, the
National Institutes of Health (R01-GM-72667) and a CAREER award
from the National Science Foundation (CHE 0547504).
Chem. Eur. J. 2007, 13, 529 –540
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
539

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