A modular approach for the synthesis of oligosaccharide mimetics

Article abstract of DOI:10.1021/jo005671u

To allow modular syntheses of oligosaccharide mimetics, the potentially trifunctional glycoside 7 was synthesized and used as a scaffold for the successive attachment of further monosaccharide derivatives to lead to the di-, tri-, and tetrasaccharide mimetics 11, 13, and 16. This synthetic strategy can also be used to prepare oligovalent neoglycoconjugates, e.g., 18, which contains nine mannosyl units. The applied concept implies numerous options for the synthesis of a wide array of structural variations, biolabeling, or solid-phase synthesis as well as combinatorial approaches.

Full text of DOI:10.1021/jo005671u

2674
J . Org. Chem. 2001, 66, 2674-2680
A Mod u la r Ap p r oa ch for th e Syn th esis of Oligosa cch a r id e
Mim etics
Anupama Patel and Thisbe K. Lindhorst*,†
Institute of Organic Chemistry, Christiana Albertina University Kiel,
Otto-Hahn-Platz 4, D-24111 Kiel, Germany
tklind@oc.uni-kiel.de
Received October 5, 2000
To allow modular syntheses of oligosaccharide mimetics, the potentially trifunctional glycoside 7
was synthesized and used as a scaffold for the successive attachment of further monosaccharide
derivatives to lead to the di-, tri-, and tetrasaccharide mimetics 11, 13, and 16. This synthetic
strategy can also be used to prepare oligovalent neoglycoconjugates, e.g., 18, which contains nine
mannosyl units. The applied concept implies numerous options for the synthesis of a wide array of
structural variations, biolabeling, or solid-phase synthesis as well as combinatorial approaches.
In tr od u ction
of relevant advantages. These include (i) simplified
synthesis, (ii) greater flexibility with regard to possible
structural modifications, (iii) feasible access to libraries
of structurally related mimetics, (iv) improvement of
stability and specificity, (v) improvement of affinity by
the incorporation of additional functional groups, and/or
(vi) increasing affinity by designing glycomimetics as
multivalent molecules.5
Various molecular scaffolds have been used for the
synthesis of oligosaccharide mimetics, such as branched,
oligofunctional non-carbohydrate core molecules6 or
monosaccharides as oligofunctional scaffolds for the
synthesis of oligosaccharide mimetics.7 Herein, we intro-
duce a trifunctional monosaccharide scaffold that can be
used for carbohydrate clustering while preserving some
of its hydroxyl groups for molecular recognition. In Figure
1 the principal structure of such a derivative is shown,
designed as an ABC-type building block, carrying three
potentially reactive sites, namely A, B, and C. These can
be subsequently addressed in coupling reactions leading
to disaccharide mimetics of type II or trisaccharide
mimetics of type III, carrying the remaining functional
group C. Eventually, C can be used in many different
ways, such as for the attachment of a further monosac-
charide unit to obtain tetrasaccharide mimetics, attach-
ment to the solid phase, biolabeling, or incorporation of
Complex oligosaccharides as part of glycoconjugates
play an important role in biological communication
processes.1 They store information in the form of their
three-dimensional structures which is “decoded” in mo-
lecular recognition processes involving carbohydrate-
recognizing proteins called lectins and selectins.2 How-
ever, the exact structures of optimal lectin ligands are
often not known, and therefore, the synthesis of car-
bohydrate ligands that are necessary for biological in-
vestigations cannot generally be based on a rational
design. While chemical and enzymatic methods for the
preparation of oligoantennary carbohydrates according
to the natural example structures has been developed
enormously during the last years,3 the synthesis of every
target molecule remains an individual and difficult task.
Consequently, efforts have been directed toward the
synthesis of structurally modified sugar-containing mol-
ecules, “glycomimetics”.4 These do not necessarily have
to be assembled by glycosidation reactions, while the
biological properties of their natural counterparts might
be preserved or even surpassed. No strict definition of
the term glycomimetic has yet been made. It seems to
be generally accepted that the approach to obtain biologi-
cally active carbohydrate-containing molecules by arti-
ficial design bears the potential to implement a number
(5) (a) Mammen, M.; Choi, S.-K.; Whitesides, G. M. Angew. Chem.
1998, 110, 2908-2953; Angew. Chem., Int. Ed. Engl. 1998, 37, 2754-
2794. (b) Kiessling, L. L.; Pohl, N. L. Chem. Biol. 1996, 3, 71-77. (c)
Lindhorst, Th. K.; Kieburg, C.; Krallmann-Wenzel, U. Glycoconjugate
J . 1998, 15, 605-613. (d) Roy, R.; Page, D.; Perez, S. F.; Bencomo, V.
V. Glycoconjugate J . 1998, 15, 251-263. (e) Sanders, W. J .; Gordon,
E. J .; Dwir, O.; Beck, P. J .; Alon, R.; Kiessling, L. L. J . Biol. Chem.
1999, 274, 5271-5278. (f) Ashton, P. R.; Hounsell, E. F.; J ayaraman,
N.; Nilsen, T. N.; Spencer, N.; Stoddart, J . F.; Young, M. J . Org. Chem.
1998, 63, 3429-3437. (g) Strong, L. E.; Kiessling, L. L. J . Am. Chem.
Soc. 1999, 121, 6193-6196. (h) Sadalapure, K.; Lindhorst, Th. K.
Angew. Chem. 2000, 112, 2066-2069; Angew. Chem., Int. Ed. 2000,
39, 2010-2013. (i) Turnbull, W. B.; Pease, A. R.; Fraser Stoddart, J .
ChemBioChem 2000, 1, 70-74.
(6) (a) Aoi, K.; Itoh, K.; Okada, M. Macromolecules 1995, 28, 5391-
5393. (b) Grandjean, C.; Rommens, C.; Gras-Masse, H.; Melnyk, O.
Angew. Chem. 2000, 112, 1110-1114; Angew. Chem., Int. Ed. 2000,
39, 1068-1072.
(7) (a) Dubber, M.; Lindhorst, Th. K. Carbohydr. Res. 1998, 310,
35-41. (b) Kitov, P. I.; Sadowska, J . M.; Mulvey, G.; Armstrong, G.
D.; Ling, H.; Pannu, N. S.; Read, R. J .; Bundle, D. R. Nature 2000,
403, 669-672.
* To whom correspondence should be addressed. Fax: Int (+49)431-
8807410.
† Dedicated to Prof. Dr. J oachim E. Thiem on the occasion of his
60th birthday.
(1) (a) Varki, A. Glycobiology 1993, 3, 97-130. (b) Essentials of
Glycobiology; Varki, A., Cummings, R., Esko, J ., Freeze, H., Hart, G.,
Marth J ., Eds.; Cold Spring Harbor Laboratory Press: Cold Spring
Harbor, 1999.
(2) (a) Lis, H.; Sharon, N. Chem. Rev. 1998, 98, 637-674. (b)
Lawrence, M. B. Curr. Opin. Chem. Biol. 1999, 3, 659-664.
(3) (a) Vankar, Y. D.; Schmidt, R. R. Chem. Soc. Rev. 2000, 29, 201-
216. (b) Gridley, J . J .; Osborn, H. M. I. J . Chem. Soc., Perkin Trans. 1
2000, 1471-1491. (c) Unverzagt, C. Angew. Chem. 1996, 108, 2507-
2510; Angew. Chem Int., Ed. Engl. 1996, 35, 2350-2353. (d) Seifert,
J .; Lergenmu¨ller, M.; Ito, Y. Angew. Chem. 2000, 112, 541-544; Angew.
Chem., Int. Ed. 2000, 39, 531-534. (e) Krˇen, V.; Thiem, J . Chem. Soc.
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10.1021/jo005671u CCC: $20.00 © 2001 American Chemical Society
Published on Web 03/23/2001

Synthesis of Oligosaccharide Mimetics
J . Org. Chem., Vol. 66, No. 8, 2001 2675
Sch em e 1a
a
Key: (a) Pd-C, H2, (Boc)2O, ethyl acetate, rt, 12 h, 91%; (b)
NH3-MeOH, 0 °C, 12 h, 94%; (c) TsCl, pyridine, 0 °C f rt, 2 h,
68%; (d) NaN3, DMF, 60 °C, 8 h, 78%; (e) Pd-C, H2, MeOH, rt, 6
h, 80%; (f) methyl acrylate, MeOH, 0 °C f rt, 15 h, 70%.
bacteria to their host cells,8 the concept outlined in Figure
1 was demonstrated on the basis of mannose as the
principal sugar. Thus, building block I was realized as
mannoside 7, II as the disaccharide analogue 11, and III
as 14. Furthermore, enlargement of 14 to the tetra-
saccharide analogue 16 was shown as well as its oligo-
merization to glycocluster 18, containing nine mannose
moieties. The prepared glycoclusters will eventually be
tested as inhibitors of mannose-specific bacterial adhe-
sion.
Syn th esis
F igu r e 1. ABC-type carbohydrate building block I , carrying
the three functions A, B, and C. These can be consecutively
functionalized with various sugar moieties to lead to di-
saccharide mimetics of type II and in the next step to
trisaccharide mimetics of type III. The remaining function C
in building block III can be utilized in different ways, e.g., for
the attachment of further carbohydrate units, for biolabeling
or solid-phase synthesis, for the combination with other
oligosaccharide mimetics, or for clustering of III to obtain the
respective multivalent analogues. ABC building block I was
realized as mannoside 7, II as compound 11, and III as the
derivative 13. Further enlargement of 13 was demonstrated
with the synthesis of 16 and 18.
The key steps in the synthetic route to the potentially
trifunctional building block 7 starting with D-mannose
are glycosidation, regioselective protection of the 6-posi-
tion of the sugar ring, and controlled Michael-analogue
addition reaction as the last step (Scheme 1). First, the
Lewis acid-catalyzed mannosylation of 2-bromoethanol9
with peracetylated mannose followed by nucleophilic
displacement of the bromo substituent in the aglycon part
of the resulting mannoside with sodium azide gave rise
to the known 2-azidoethyl mannoside derivative 1.10
Then, catalytic hydrogenation of the azide group in 1
succeeded in order to obtain the respective amine. This
reaction was carried out in the presence of Boc2O to avoid
a further group to add affinity. Furthermore, coupling
to other oligosaccharide mimetics or clustering on an
oligovalent scaffold is possible in order to obtain oligo-
valent oligosaccharide mimetics. This concept also im-
plies the possibility to synthesize oligosaccharide ana-
logues with mixed carbohydrate configurations as well
as combinatorial applications.
As we have been especially interested in the develop-
ment of mannose-containing glycoclusters for the inhibi-
tion of mannose-specific adhesion of Escherichia coli
(8) (a) Ko¨tter, S.; Krallmann-Wenzel, U.; Ehlers, S.; Lindhorst, Th.
K. J . Chem. Soc., Perkin Trans. 1 1998, 2193-2200. (b) Ko¨nig, B.;
Fricke, T.; Wassmann, A.; Krallmann-Wenzel, U.; Lindhorst, Th. K.
Tetrahedron Lett. 1998, 39, 2307-2310.
(9) Dahmen, J .; Frejd, T.; Gro¨nberg, G.; Lave, T.; Magnusson, G.;
Noori, G. Carbohydr. Res. 1983, 116, 303-307.
(10) Chernyak, A. Y.; Sharma, G. V. M.; Kononov, L. O.; Radha
Krishna, P.; Levinsky, A. B.; Kochetkov, N. K.; Ramarao, A. V.
Carbohydr. Res. 1992, 223, 303-309.

2676 J . Org. Chem., Vol. 66, No. 8, 2001
Patel and Lindhorst
Sch em e 2a
O f N acetyl group migration and to achieve in situ
protection of the resulting free amine in the same
reaction vessel. This procedure furnished the acetylated
N-Boc-protected mannoside 2 in 91% yield. For 2 an
upfield shift of the protons adjacent to the NHBoc group
(3.36 compared to 3.46 ppm for the azide 1) and a singlet
1
for the Boc group at 1.46 ppm were observed in its H
NMR spectrum. Mannoside 2 was easily deacetylated to
3, which was regioselectively tosylated to the 6-activated
glycoside 4. A nucleophilic substitution reaction using
sodium azide afforded the 6-azido-6-deoxy-mannoside 5,
which was reduced to the corresponding amine 6 by
catalytic hydrogenation in 92% overall yield.
The exhaustive Michael-analogue addition of primary
amines to methyl acrylate is known as one of two
synthetic steps in the construction of PAMAM dendrimer
generations.11 While in this reaction an excess of methyl
acrylate is used to obtain the bis-addition product, a
stoichiometric amount of methyl acrylate allowed the
conversion of the amine 6 into the mono-Michael adduct
7 in 70% yield. To avoid the formation of polymeric side
products resulting from photochemical reactions of meth-
yl acrylate, the reaction was carried out under the
exclusion of light. The structure of 7 was easily confirmed
1
by H and 13C NMR spectroscopy, which displayed the
signals for the methoxycarbonylethyl spacer as expected.
The chemical shifts for singlets of methoxycarbonyl
1
groups in H NMR are normally obtained in the range of
3.6-4.0 ppm, and a corresponding chemical shift of 3.63
ppm was recorded for the methoxycarbonyl group of 7
1
when the H NMR spectrum was recorded in acetone-d6.
However, when 7 was dissolved in methanol-d4 or D2O,
respectively, the CH3-singlet was observed at 3.33 ppm
after 12 h at ambient temperature, whereas the chemical
shifts of the other signals remained unchanged. NMR
studies revealed that this change was due to ester
hydrolysis of the methoxycarbonyl group by water, which
was also present in the methanol-d4 used. The observed
singlet at 3.33 ppm corresponds to the CH3 group of
resulting methanol. In the 13C NMR spectrum of 7, two
peaks were observed for the carbonyl carbon of the Boc
group (at 158.9 and 158.8 ppm), thus revealing the
presence of E,Z isomers that result from the partial
double-bond character of the Boc C-N bond. As a result
of this isomerism, broadening of the signal for the
a
Key: (a) CH2Cl2, rt, 6 h, 89%; (b) NH3-MeOH, rt, 2 h, 91%;
(c) LiOH‚H2O, MeOH-H2O (2:1), 0 °C, 12 h, quant; (d) HATU,
DIPEA, DMF, rt f 40 °C, 12 h, 43%; (e) Me2S-CF3CO2H (1:2), 0
°C, 4 h, quant; (f) HATU, DIPEA, DMF, rt f 40 °C, 12 h, 71%.
1
NCH2 protons in the H NMR spectrum. Furthermore,
the structure of 9 was confirmed by the appearance of a
peak for the thiocarbonyl group (CdS) in the 13C NMR
spectrum; MALDI-TOF analysis gave the expected peak
(m/z ) 798.6 for [M + H]+). Compound 9 can be regarded
as a disaccharide mimetic in which two monosaccharide
units are connected by nonglycosidic linkages. Treatment
of 9 under mild basic conditions afforded the OH-
unprotected methyl ester 10 in quantitative yield. Using
an excess of lithium hydroxide in aqueous methanol led
to concomitant hydrolysis of the acetates and the methyl
ester providing the propanoic acid derivative 11. This was
subjected to a peptide coupling reaction in order to
prepare the trisaccharide mimetic of type III (Figure 1).
Methyl 6-amino-6-deoxy-R-D-mannopyranoside (12)14 was
used as the amino component and uronium salt HATU15
as coupling reagent. This reaction provided the desired
glycopeptide mimetic 13, which was purified by two
subsequent size-exclusion chromatography steps. First
gel permeation chromatography (GPC) using Sephadex
1
anomeric proton is observed in the H NMR spectrum.
Mannoside 7 represents the desired building block of
type I as suggested in Figure 1. It carries three poten-
tially reactive functions, an unprotected secondary amine,
a methyl ester that is cleavable under basic conditions,
and a Boc-protected amine that can be liberated under
mild acidic conditions, which leave the glycosidic bond
intact. The secondary amino group in 7 can be function-
alized by thiourea bridging12 or peptide coupling, for
example, and was addressed first (Scheme 2). Thus, 7
was reacted with acetylated mannosyl isothiocyanate 8,13
allowing the formation of the partially protected thiourea
derivative 9. The formation of the thiourea bridge was
confirmed by downfield shifts (in the range of 1 ppm) of
the signals for both diastereotopic H-6 as well as the
(11) Meltzer, A. D.; Tirrell, D. A.; J ones, A. A.; Inglefield, P. T.;
Hedstrand, D. M.; Tomalia, D. A. Macromolecules 1992, 25, 4541-
4548.
(12) Lindhorst, Th. K.; Kieburg, C. Angew. Chem. 1996, 108, 2083-
2086; Angew. Chem., Int. Ed. Engl. 1996, 35, 1953-1956.
(13) Lindhorst, Th. K.; Kieburg, C. Synthesis 1995, 1228-1230.
(14) Wang, P.; Shen, G.-J .; Wang, Y.-F.; Ichikawa, Y.; Wong, C.-H.
J . Org. Chem. 1993, 58, 3985-3990.
(15) Carpino, L. A. J . Am. Chem. Soc. 1993, 115, 4397-4398.

Synthesis of Oligosaccharide Mimetics
J . Org. Chem., Vol. 66, No. 8, 2001 2677
Sch em e 3a
a
Key: (a) 14, HATU, DIPEA, DMF, rt f 40 °C, 12 h, 30%.
LH-20 and methanol as the eluent allowed the isolation
of a mixture of 13 and 11, which was separated from
reagent impurities. Then GPC on Bio-Gel P-2 using
15mM NH4HCO3 buffer as the eluent was suited to
separate 13 from 11 and furnished 13 in 43% yield and
35% recovered carboxylic acid 11. The NMR spectra of
13 showed the expected signals of the additional mono-
meric mannoside unit with its methyl aglycone as a
useful NMR reporter group. The MALDI-TOF spectrum
showed the correct [M + H]+ peak at m/z ) 791.2.
The obtained trisaccharide mimetic 13 carries a Boc-
protected amino group that was regarded as “function
C” in Figure 1. According to the possibilities outlined in
Figure 1, 13 can be modified in a variety of ways. Here,
we demonstrate the functionalization of 13 with another
mannose moiety leading to the tetrasaccharide mimetic
16 and, furthermore, the utilization of 13 as a molecular
wedge leading to the trivalent conjugate 18 (Scheme 3).
To synthesize the tetrasaccharide mimetic 16, 13 was
subjected to Boc deprotection in an anhydrous mixture
of trifluoroacetic acid and dimethyl sulfide (2:1)16 to yield
the respective free amine 14. In this reaction after
concentration of the reaction mixture it was important
to neutralize the last traces of TFA with aqueous am-
monia in order to avoid trifluoroacetylation of the product
amine 14 in the next step. The amine 14 was then sub-
jected to a peptide-coupling reaction using the manno-
uronic acid derivative 15. Analogous reaction conditions
as used previously for synthesis of compound 13 afforded
the mannose cluster 16 in 70% yield. The anomeric
hydrogen and carbon atoms resonated as distinct signals
both in the 1H as well as the 13C NMR spectrum. The
MALDI-TOF mass spectrum showed [M + H]+ at m/z )
881.8.
For clustering of 14, trimesic acid (17) was used as a
trivalent core (Scheme 3). Deprotection of 13 to 14,
followed by HATU-mediated peptide-coupling reaction
with 17, afforded the complex glycocluster 18 in 30%
yield. Compound 18 resembles a trimeric derivative of
the trisaccharide mimetic 14. Its purification was prob-
lematic and succeeded best when it was carried out using
GPC on Bio-gel P-2 on a small scale. NMR spectra of 18
were very similar to those of 13 except for the missing
signals for the Boc group and the appearance of those
for the aromatic core moiety, which were detected as
expected (8.34 ppm in 1H NMR). A clean MALDI-TOF
mass spectrum (m/z ) 2227.8 for [M + H]+) further
confirmed the structure of 18.
Discu ssion a n d Con clu sion s
En route to the oligosaccharide mimetics 13, 16, and
18, respectively, three peptide-coupling reactions were
elaborated. Interestingly, the coupling step proceeded
(16) Katano, K.; Aoyagi, H. A. Y.; Overhand, M.; Sucheck, S. J .;
Stevens, W. C., J r.; Hess, C. D.; Zhou, X.; Hecht, S. M. J . Am. Chem.
Soc. 1998, 120, 11285-11296.

2678 J . Org. Chem., Vol. 66, No. 8, 2001
Patel and Lindhorst
uncorrected. For MALDI-TOF measurements the samples
were prepared as solutions in TFA-acetonitrile-water, 0.1:
2:1, with a concentration of 1 mg of compound in 1 mL of
solution. Dihydroxybenzoic acid (DHB) was used as the matrix
for the crystallization of compounds 9, 11, 13, 16, and 18. The
mass peaks obtained with these samples were calibrated in
reference to the [M + H]+ peaks of angiotensin II (1046.54),
angiotensin I (1296.69), bombesin (1619.82), and to the [2M
+ H]+ peak of R-cyano-4-hydroxycinamic acid (380.02). Optical
rotations were recorded at the Na D line, 589 nm, 20 °C, cell
length 10 cm. Elemental analyses were carried out in the
microanalytical laboratory of the Institut fu¨r Organische
Chemie der Universita¨t Hamburg. Methyl R-D-mannopyran-
uronic acid 15 was synthesized from methyl R-D-manno-
pyranoside according to a literature procedure.17
with yields around 70%, when 14 was used as the amine
component. Consequently, cluster 18, in which three
peptide linkages had to be formed, was obtained in 30%
overall yield. On the other hand, peptide coupling under
the same conditions proceeded with modest yields when
the carboxylic function of 11 was addressed as significant
amounts of 11 did not react in this step. A possible reason
for the limited reactivity of this system may be the
formation of an intramolecular hydrogen bond between
the carboxylic acid proton and the nitrogen atom result-
ing in a stable six-membered-ring arrangement.
For the structural characterization of the OH-unpro-
tected compounds 9, 10, 13, 16, and 18 with molecular
weights 797.8, 629.7, 790.8, 880.8, and 2228.7, respec-
tively, extensive NMR-spectroscopic experiments were
2-ter t-Bu t yloxyca r b on yla m id oet h yl 2,3,4,6-Tet r a -O-
a cetyl-r-D-m a n n op yr a n osid e (2). A suspension of the azide
1 (7.10 g, 17.02 mmol), activated Pd catalyst (10% on charcoal,
100 mg), and di-tert-butyl dicarbonate (5.57 g, 25.53 mmol) in
ethyl acetate (50 mL) was hydrogenated under atmospheric
pressure for 6 h at rt. Then the reaction mixture was filtered
through a thin Celite bed, and the filtrate was concentrated.
The crude product was purified by flash chromatography (ethyl
acetate-petroleum ether, 1:2) to afford the Boc-protected
mannoside 2 in the form of a white solid (7.60 g, 15.47 mmol,
1
necessary. While some parts of their H NMR spectra are
rather poorly resolved, the anomeric protons of the
contained sugar moieties are always separated from the
other signals and can be used as immediate indicators
for the success of the reaction. 13C NMR spectra of these
compounds, on the other hand, were well resolved, and
thus, together with 2D NMR experiments all hydrogen
and carbon atoms of each derivative could be detected
and all signals unequivocally assigned. The structures
of all glycoclusters were confirmed by MALDI-TOF mass
spectrometry, which was also an excellent and important
tool for monitoring the reactions described herein.
On the basis of the presented building block system, a
wide array of oligosaccharide mimetics is accessible
without utilizing the notoriously difficult glycosylation
chemistry. The suggested concept implies synthetic routes
for biolabeling, combinatorial approaches, or synthesis
of oligovalent neoglycoconjugates, for example. It is
important to note that the orthogonal functional group
pattern in 7 allows the successive attachment of very
different (sugar) moieties including pharmacophores and
the preparation of “mixed” glycoclusters, representing
various three-dimensional ensembles of functional groups
that are otherwise assembled by the oligosaccharide parts
of complex glycoconjugates. This might be of relevance
when bacterial adhesion of wild-type strains has to be
inhibited, which normally carry pili of different specifici-
ties. We will explore the presented concept to optimize
ligand structures for various lectins and adhesion sys-
tems.
1
91%): [R]D ) +36° (c ) 1.10 in CHCl3); H NMR (400 MHz,
CDCl3) δ 5.33 (dd, J 3,4 ) 9.7 Hz, 1H, H-3), 5.28 (dd, J 4,5 ) 9.2
Hz, 1H, H-4), 5.26 (dd, J 2,3 )3.1 Hz, 1H, H-2), 4.93 (s, 1H,
NH), 4.83 (d, J 1,2 ) 1.5 Hz, 1H, H-1), 4.28 (dd, J 6a,6b ) 12.2
Hz, 1H, H-6a), 4.10 (dd, J 6a,6b ) 12.2, J 5,6b ) 5.1 Hz, 1H, H-6b),
3.98 (ddd, J 5,6 ) 2.5, J 5,6b ) 5.1 Hz, 1H, H-5), 3.76 (ddd, 1H,
OCHa), 3.54 (ddd, 1H, OCHb), 3.36 (mc, 2H, CH2N), 2.18, 2.12,
2.05, 2.01 (each s, each 3H, 4 COCH3), 1.46 (s, 9H, t-Bu); 13C
NMR (100.67 MHz, CDCl3) δ 172.7, 172.0, 171.9, 171.8 (4
COCH3), 158.8 (BocCO), 99.3 (C-1), 80.6 (C(CH3)3), 71.2 (C-2),
71.1 (C-3), 70.3 (C-5), 68.6 (OCH2), 67.7 (C-4), 63.9 (C-6), 41.4
(CH2N), 29.2 (C(CH3)3), 21.1, 21.07, 21.02 (4 COCH3). Anal.
Calcd for C21H33NO12 (491.49): C, 51.32; H, 6.77; N, 2.85.
Found: C, 51.30; H, 6.84; N, 2.83.
2-ter t-Bu tyloxycar bon ylam idoeth yl r-D-m an n opyr an o-
sid e (3). To a solution of the tetraacetylated mannoside 2 (7.60
g, 15.47 mmol) in methanol (50 mL), was added saturated
NH3-MeOH (10 mL) at 0 °C and the reaction mixture was
stirred at 0 °C for 2 h. Then it was concentrated and the crude
product was purified by flash chromatography (MeOH-
CH2Cl2, 1:10) to yield 3 in the form of a white solid (4.67 g,
14.45 mmol, 94%): [R]D ) +60° (c ) 1.21 in MeOH); 1H NMR
1
(400 MHz, [D4]-MeOH): δ ) 4.76 (d, J 1,2 ) 1.5 Hz, J C1,H1
)
168.5, 1H, H-1), 3.82 (dd, J 6a,5 ) 2.6 Hz, 1H, H-6a), 3.81 (dd,
J 2,3 ) 3.1 Hz, 1H, H-2), 3.75-3.68 (m, 2H, H-6b, OCHa), 3.69
(dd, J 3,4 ) 9.7 Hz, 1H, H-3), 3.61 (dd, J 4,3 ) 9.7 Hz, 1H, H-4),
3.56-3.44 (m, 2H, H-5, OCHb), 3.24 (mc, 2H, NCH2), 1.44 (s,
9H, t-Bu); 13C NMR (100.62 MHz, [D4]-MeOH): δ ) 158.3
(BocCO), 101.7 (C-1), 80.1 (C(CH3)3), 74.7 (C-5), 72.5 (C-3), 72.1
(C-2), 68.6 (C-4), 67.6 (OCH2), 62.9 (C-6), 41.2 (CH2N), 28.8
(C(CH3)3). Anal. Calcd for C13H25NO8 × 1H2O (341.36): C,
45.74; H, 7.97; N, 4.10. Found: C, 45.68; H, 7.74; N, 3.89.
Exp er im en ta l Section
Gen er a l Meth od s a n d Ma ter ia ls. TLC as well as flash
chromatography were performed on silica gel, and detection
was carried out by charring with 20% ethanolic sulfuric acid
solution containing 5% of R-naphthol and under UV light when
applicable. For size-exclusion chromatography, Sephadex LH-
20 was used with methanol as the eluent and Biogel P-2 with
15 mM aqueous NH4HCO3 buffer (pH ) 7.8-8.0) as the eluent.
Organic solutions were concentrated using a rotary evaporator
at bath temperatures <45 °C. Aqueous solutions were con-
centrated by lyophilization. 1H and 13C NMR spectra were
recorded at 298 K at 400 MHz (for 1H, 100.67 MHz for 13C
2-ter t-Bu t yloxyca r b on yla m id oet h yl 6-O-(t olu en e-4-
su lfon yl)-r-D-m a n n op yr a n osid e (4). To a solution of the
O-unprotected mannoside 3 (4.67 g, 14.45 mmol) in pyridine
(20 mL) was added tosyl chloride (4.13 g, 21.68 mmol) at 0 °C
under argon atmosphere. Then the reaction mixture was
allowed to attain rt and was further stirred for 2 h. The
reaction was quenched with MeOH at 0 °C and the solvent
was removed. The crude product so obtained was purified by
flash chromatography (CH2Cl2-MeOH, 10:1) to give the 6-O-
tosylated derivative 4 (4.60 g, 9.64 mmol, 68%) as a white
1
NMR) or 500 MHz (for H, 125.84 MHz for 13C NMR). Chemical
shifts are given in ppm relative to internal TMS (0.00 ppm
for 1H and 13C NMR), and when the samples were measured
in D2O the spectra were calibrated referring to internal HOD
1
solid: [R]D ) +36° (c ) 1.96 in MeOH); H NMR (400 MHz,
[D4]-MeOH): δ ) 7.80 (d, J ) 8.1 Hz, 2H, aryl-H), 7.40 (d, J
) 8.1 Hz, 2H, aryl-H), 4.66 (s, 1H, H-1), 4.32 (dd, J 5,6b ) 1.5,
J 6a,6b ) 10.7 Hz, 1H, H-6b), 4.17 (dd, J 6a,6b ) 10.7 Hz, 1H,
1
(4.63 ppm for H NMR) and in the case of 13C NMR to MeOH-
d4 (49.30 ppm for 13C NMR) which was added to the solution.
J values are given in Hz. Two-dimensional 1H-1H and 1H-
13C COSY (HMQC) experiments were performed for complete
signal assignments wherever necessary. Melting points are
(17) Davis, N. J .; Flitsch, S. L. Tetrahedron Lett. 1993, 34, 1181-
1184.

Synthesis of Oligosaccharide Mimetics
J . Org. Chem., Vol. 66, No. 8, 2001 2679
H-6a), 3.78 (dd, J 2,3 ) 3.1 Hz, 1H, H-2), 3.66 (mc, J 5,6a) 6.6,
J 5,6b ) 1.5 Hz, 1H, H-5), 3.64 (dd, J 3,4 ) 9.7 Hz, 1H, H-3), 3.6
(mc, 1H, OCHa), 3.52 (dd, 1H, H-4), 3.4(mc, 1H, OCHb), 3.2 (mc,
2H, CH2N), 2.45 (s, 3H, TsCH3), 1.43 (s, 9H, t-Bu); 13C NMR
(100.62 MHz, [D4]-MeOH): δ ) 158.1 (BocCO), 146.84 (aryl-
Cq), 134.81 (aryl-Cq), 131.4 (aryl-CH), 131.2 (aryl-CH), 129.6
(2 aryl-CH), 102.1 (C-1), 80.1 (C(CH3)3), 72.8 (C-5), 72.6 (C-3),
72.2 (C-2), 71.7 (C-6), 68.5 (C-4), 68.1 (OCH2), 41.5 (CH2N),
29.2 (C(CH3)3, 22.0 (TsCH3). Anal. Calcd for C20H31NO10S ×
1H2O (495.54): C, 48.48; H, 6.71; N, 2.83, S, 6.47. Found: C,
48.82; H, 6.51; N, 3.22, S, 6.34.
sid e (9). Mannoside 7 (1.10 g, 2.69 mmol) and the mannosyl
isothiocyanate derivative 8 (1.15 g, 2.96 mmol) were dissolved
in dry CH2Cl2 (10 mL) and stirred at rt for 12 h. When the
reaction was complete (monitored by TLC with MeOH-
CH2Cl2, 1:9) it was concentrated and the crude product was
purified by flash chromatography (MeOH-CH2Cl2, 1:9) to give
the thiourea-bridged disaccharide mimetic 9 as a white solid
1
(1.90 g, 2.38 mmol, 89%): [R]D ) +7° (c ) 1.30 in MeOH); H
NMR (500 MHz, [D4]-MeOH): δ ) 6.20 (d, J 1′,2′ ) 1.9 Hz, 1H,
H-1′), 5.36-5.25 (m, 3H, H-2′, H-4′, H-3′), 5.02 (s, 1H, H-1),
4.35 (dd, J 6′,5′ ) 4.1, J 6a′,6b′ ) 12.0 Hz, 1H, H-6a′), 4.3-4.0 (m,
J 6′,5′ ) 4.1, J 6a′,6b′ ) 12.0 Hz, 4H, H-5′, H-6b′, NCH2), 3.96-
3.85 (m, 3H, H-5, H-6a, H-6b), 3.83 (dd, J 1,2 ) 1.6, J 2,3 ) 2.8
Hz, 1H, H-2), 3.73 (dd, J 3,4 ) 9.2 Hz, 1H, H-3), 3.68 (s, 3H,
CO2CH3), 3.66 (mc, 1H, OCHa), 3.60-3.50 (m, 2H, H-4, OCHb),
3.23 (mc, 2H, CH2NHBoc), 2.90 (t, 2H, CH2CO), 1.90, 2.00, 2.10,
2.20 (each s, each 3H, 4 COCH3), 1.44 (s, 9H, t-Bu); 13C NMR
(125.84 MHz, [D4]-MeOH): δ ) 186.0 (CdS), 172.9, 172.1,
171.9, 171.7 (4 COCH3, CO2CH3), 158.8 (BocCO), 102.5 (C-1),
82.9 (C(CH3)3), 80.6 (C-1′), 72.7 (C-3), 72.1 (C-2, C-5), 71.5 (C-
5′), 71.4 (C-3′), 71.1 (C-2′), 69.4 (C-4), 68.5 (OCH2), 67.9 (C-4′),
63.7 (C-6′), 53.43 (NCH2), 52.7 (CO2CH3), 51.5 (C-6), 41.5
(CH2NHBoc), 32.8 (CH2CO), 29.2 (C(CH3)3), 21.16 (4 COCH3);
MALDI-TOF MS: m/z ) 798.6 [M+H]+, 820.7 [M+Na]+ and
836.6 [M+K]+ observed for C32H51N3O18S (797.28). Anal. Calcd
for C32H51N3O18S x 1H2O (815.84): C, 47.11; H, 6.55; N, 5.15;
S, 3.93. Found: C, 47.19; H, 6.46; N, 5.09; S, 4.14.
2-ter t-Bu t yloxyca r b on yla m id oet h yl 6-a zid o-6-d eoxy-
r-D-m a n n op yr a n osid e (5). A suspension of the tosylated
mannoside 4 (4.60 g, 9.64 mmol), NaN3 (1.90 g, 29.22 mmol)
and a catalytic amount of tetra-n-butylammonium iodide (100
mg) in dry DMF (25 mL) was stirred at 60 °C for 8 h. After
completion of the reaction (monitored by TLC with CH2Cl2-
MeOH, 10:1) DMF was removed under high vacuum and the
residual solid was dissolved in ethyl acetate and filtered
through a thin Celite bed to remove the excess of NaN3 from
the product mixture. Then the solvent was removed and the
crude product was purified by flash chromatography (CH2Cl2-
MeOH, 10:1) to yield the azide 5 (2.60 g, 7.47 mmol, 78%) as
1
a colorless syrup: [R]D ) +29° (c ) 4.43 in MeOH); H NMR
(400 MHz, [D4]-MeOH): δ ) 4.77 (s, 1H, H-1), 3.82 (dd, J 2,1
)
1.5, J 2,3 ) 3.1 Hz, 1H, H-2), 3.74 (mc, 1H, OCHb), 3.68 (dd, J 3,4
) 9.2 Hz, 1H, H-3), 3.66 (mc, 1H, H-5), 3.57 (dd, 1H, H-4), 3.43
(dd, J 6a,5 ) 6.6, J 6a,6b ) 13.2 Hz, 1H, H-6a), 3.43-3.53 (m, J 6a,6b
) 13.2 Hz, 2H, H-6b, OCHa), 3.24 (mc, 2H, CH2N), 1.45 (s, 9H,
t-Bu); 13C NMR (100.62 MHz, [D4]-MeOH): δ ) 158.9 (BocCO),
102.2 (C-1), 80.6 (C(CH3)3), 74.3 (C-5), 72.7 (C-3), 72.4 (C-2),
69.8 (C-4), 68.2 (OCH2), 53.3 (C-6), 41.6 (CH2N), 29.2 (C(CH3)3).
Anal. Calcd for C13H24N4O7 × 1H2O (366.1): C, 42.61; H, 7.10.
Found: C, 42.82; H, 6.98.
2-ter t-Bu tyloxyca r bon yla m id oeth yl 6-d eoxy-6-N-[(R-D-
m a n n op yr a n osyl)th ioca r ba m oyl]-N-[2-(m eth oxyca r bon -
yl)eth yl]a m in o-r-D-m a n n op yr a n osid e (10). A solution of
compound 9 (0.142 g, 0.178 mmol) in MeOH (2 mL) was treated
with saturated NH3-MeOH solution (2 mL) at 0 °C for 2 h.
Then the solvent was evaporated and the crude product was
purified by flash chromatography (MeOH-CH2Cl2, 1:1) provid-
ing 10 (0.102 g, 0.161 mmol, 91%) as a light yellow solid, which
showed hygroscopic properties: [R]D ) -41° (c ) 0.97 in H2O);
1H NMR (500 MHz, D2O): δ ) 5.97 (d, J 1′,2′ ) 1.9 Hz, 1H, H-1′),
4.85 (bs, 1H, H-1), 4.18 (mc, 1H, NCHa), 4.0 (mc, 1H, NCHb),
3.96-3.91 (m, 2H, H-2, H-2′), 3.81-3.73 (m, J 5,6a ) 4.1 Hz,
J 5′,6a′ ) 2.5 Hz, J 6a′,6b′ ) 13.6 Hz, 4H, H-6a, H-6b, H-6a′, H-6b′),
3.74 (mc, 1H, H-5), 3.71-3.67 (m, 2H, H-3′, H-3), 3.66 (s, 3H,
CO2CH3), 3.58-3.45 (m, 4H, OCH2, H-4′, H-4), 3.41 (mc, 1H,
H-5′), 3.23 (mc, 2H, CH2NHBoc), 2.83 (mc, 2H, CH2CO), 1.39
(s, 9H, t-Bu); 13C NMR (125 MHz, D2O): δ ) 183.2 (CdS),
174.9 (CO2CH3), 158.4 (BocCO), 100.5 (C-1), 83.5 (C′-1), 81.3
(C(CH3)3), 77.9 (C′-5), 74.5 (C′-4, C-4), 71.3 (C-5), 70.3, 70.2
(C′-2, C-2), 67.4 (OCH2), 67.2 (C-3, C′-3), 61.2 (C′-6), 52.8
(CO2CH3), 52.0 (C-6), 49.7 (NCH2), 39.9 (CH2NHBoc), 32.1
(CH2CO), 28.1 (C(CH3)3); MALDI-TOF MS m/z ) 630.8 [M +
H]+, 652.8 [M + Na]+ and 668.8 [M + K]+ obsd for C24H43N3O14S
(629.24). Anal. Calcd for C24H43N3O14S‚1H2O (647.69): C,
44.51; H, 7.00; N, 6.49; S, 4.95. Found: C, 44.3; H, 6.94; N,
6.63; S, 5.00.
2-ter t-Bu tyloxyca r bon yla m id oeth yl 6-Deoxy-6-N-[(r-D-
m a n n op yr a n osyl)t h ioca r b a m oyl]-N-[2-[(6′′-d eoxy-1′′-O-
m eth yl-r-D-m an n opyr an os-6′′-yl)car bam oyl]eth yl]am in o-
r-D-m a n n op yr a n osid e (13). The thiourea derivative 9 (500
mg, 0.627 mmol) was dissolved in MeOH-H2O (1:2; 5 mL) and
treated with LiOH‚1H2O (131.6 mg, 3.135 mmol) at 0 °C for
12 h. Then the pH of the basic reaction mixture was neutral-
ized at 0 °C to a value of 6 by the careful addition of 2 N HCl
solution. The clear solution that was obtained was freeze-dried
to afford the crude carboxylic acid 11 as a white solid (385
mg), which was subjected to peptide coupling without purifica-
tion. It was dissolved in dry DMF (10 mL), and the 6-amino-
modified methyl mannoside 12 (144 mg, 0.751 mmol), HATU
(285 mg, 0.751 mmol), and Hu¨nig’s base (DIPEA, 0.22 mL, 1.25
mmol) were added at rt under argon atmosphere. The reaction
mixture was stirred at 40 °C for 12 h, and then DMF was
removed in vacuo. The resulting crude product was a pale
yellow syrup that was subjected to gel permeation chroma-
tography on Biogel P-2. This afforded the title compound 13
(215 mg, 0.272 mmol, 43%) with 145 mg (0.235 mmol, 37%) of
the intermediate acid 11 being recovered in pure form. Product
13 was obtained as a white lyophilisate that showed hygro-
2-ter t-Bu tyloxyca r bon yla m id oeth yl 6-a m in o-6-d eoxy-
r-D-m a n n op yr a n osid e (6). To a solution of the azide 5 (2.60
g, 7.47 mmol) in MeOH (20 mL) was added activated Pd-
catalyst (10% on charcoal, 50 mg), and the reaction mixture
was hydrogenated under atmospheric pressure for 6 h at rt.
Then it was filtered through a thin Celite bed and the filtrate
was concentrated. The crude product was purified by flash
chromatography (MeOH-CH2Cl2, 1:1) to give 6 (1.93 g, 5.99
mmol, 80%) as a white solid: [R]D ) +45° (c ) 0.80 in MeOH);
1H NMR (400 MHz, [D4]-MeOH): δ ) 4.74 (s, 1H, H-1), 3.8 (s,
1H, H-2), 3.6-3.8 (m, 2H, OCHb, H-3), 3.55-3.4 (m, 2H, OCHa,
H-5), 3.5 (dd, 1H, H-4), 3.3 (d, 1H, H-6b), 3.22 (mc, 2H, CH2N),
2.8 (mc, 1H, H-6a), 1.5 (s, 9H, t-Bu); 13C NMR (100.62 MHz,
[D4]-MeOH): δ ) 158.4 (BocCO), 101.6 (C-1), 79.1 (C(CH3)3),
74.3 (C-5), 72.3 (C-3), 72.0 (C-2), 69.8 (C-4), 67.3 (OCH2), 43.5
(C-6), 41.2 (CH2N), 28.7 (C(CH3)3). A correct elemental analysis
for C13H26N2O7 (322.36) was not obtained.
2-ter t-Bu t yloxyca r b on yla m id oet h yl 6-d eoxy-6-[N-(2-
m eth oxycar bon yleth yl)am in o]-r-D-m an n opyr an oside (7).
To a solution of the amino-functionalized mannoside 6 (1.93
g, 5.99 mmol) in dry MeOH (8 mL) was added freshly distilled
methyl acrylate (0.54 mL, 5.99 mmol) at 0 °C under argon
atmosphere and the reaction mixture was stirred in the dark
for 15 h at rt. Then it was concentrated and the residue was
purified by flash chromatography (CH2Cl2-MeOH, 1:1) to
afford the Michael-adduct 7 (1.70 g, 4.16 mmol, 70%) as a white
1
solid: [R]D ) +35° (c ) 1.50 in MeOH); H NMR (400 MHz,
[D4]-MeOH): δ ) 4.74 (s, 1H, H-1), 3.80 (s, 1H, H-2), 3.76-
3.6 (m, 3H, H-5, OCHa, H-3), 3.68 (s, 3H, CO2CH3), 3.53-3.43
(m, 2H, H-4, OCHb), 3.34-3.15 (m, 2H, CH2NHBoc), 2.98 (dd,
1H, H-6a), 2.90 (mc, 2H, NCH2), 2.76 (dd, 1H, H-6b), 2.57 (mc,
2H, CH2CO), 1.43 (s, 9H, t-Bu); 13C NMR (100.62 MHz, [D4]-
MeOH): δ ) 174.9 (CO2CH3), 158.9 (BocCO), 102.1 (C-1), 80.5
(C(CH3)3), 72.8 (C-3), 72.5 (C-5), 72.4 (C-2), 71.2 (C-4), 68.0
(OCH2), 52.6 (CO2CH3), 52.2 (C-6), 46.3 (NCH2), 41.6 (CH2-
NBoc), 35.0 (CH2CO), 29.26 (C(CH3)3). Anal. Calcd for
C
17H32N2O9‚x 1H2O (426.46): C, 47.88; H, 8.04; N, 6.57.
Found: C, 48.34; H, 7.91; N, 6.17.
2-ter t-Bu tyloxyca r bon yla m id oeth yl 6-d eoxy-6-N-[(2′,3′,
4′,6′-tetr a -O-a cetyl-r-D-m a n n op yr a n osyl)th ioca r ba m oyl]-
N-[2-(m eth oxyca r bon yl)eth yl]a m in o-r-D-m a n n op yr a n o-

2680 J . Org. Chem., Vol. 66, No. 8, 2001
Patel and Lindhorst
scopic properties: [R]D ) -30° (c ) 1.15 in H2O); 1H NMR (500
MHz, D2O) δ 5.5 (bs, 1H, H-1′), 4.86 (bs, 1H, H-1), 4.68 (d,
J 1′′,2′′ ) 1.6 Hz, 1H, H-1′′), 4.2 (bs, 1H, NCHa), 3.93 (bs, 1H,
H-2′), 3.90 (bs, 1H, NCHb), 3.88 (bs, 1H, H-2), 3.87 (dd, J 2′′,3′′
) 3.2 Hz, 1H, H-2′′), 3.83 (bs, 1H, H-6a′), 3.76-3.70 (m, 3H,
H-6a, H-3, H-6b), 3.70-3.64 (m, 4H, H-5, H-3′′, H-3′, H-6b′),
3.61 (d, 1H, H-6a′′), 3.60-3.45 (m, 6H, H-4′′, OCHa, H-4, H-4′,
H-5′′, OCHb), 3.40 (mc, J 5′,6a′ ) 3.8, J 5′,6b′ ) 6.0, J 4′,5′ ) 9.8 Hz,
1H, H-5′), 3.35 (mc, 1H, H-6b′′), 3.33 (s, 3H, OCH3), 3.20 (mc,
2H, CH2NHBoc), 2.72 (mc, 2H, CH2CO), 1.4 (s, 9H, t-Bu); 13C
NMR (125.84 MHz, D2O, MeOH-d4) δ 183.5 (CdS), 174.5
(CONH), 158.8 (BocCO), 101.57 (C-1′′), 100.32 (C-1), 83.87 (C-
1′), 81.65 (C(CH3)3), 78.23 (C-5′), 74.18 (C-3′), 71.4 (C-2′), 71.37
(C-4′′), 71.1 (C-5, C-3′′), 70.66 (C-3), 70.59 (C-2, C-2′′), 68.82
(C-4′, C-5′′), 68.3 (C-4), 67.73 (OCH2), 61.95 (C-6′), 55.44
(OCH3), 52.29 (C-6), 51.3 (NCH2), 40.82 (C-6′′), 40.29 (CH2-
NHBoc), 34.22 (CH2CO), 28.47 (C(CH3)3); MALDI-TOF MS m/z
) 791.2 [M + H]+, 813.2 [M + Na]+ and 829.2 [M + K]+
83.57 (C-1′), 77.93 (C-5′), 73.85 (C-3′′), 72.56 (C-5′′′, C-2′), 71.06
(C-4′′), 70.78 (C-5), 70.76 (C-3′), 70.55(C-3′′′), 70.28 (C-2), 70.26
(C-2′′), 70.04 (C-2′′′), 68.74 (C-3, C-4′′′), 68.48 (C-5′′, C-4), 67.02
(C-4′), 66.26 (OCH2), 61.57 (C-6′), 55.63, 55.11 (2 OCH3), 52.01
(C-6), 50.92 (NCH2), 40.47 (C-6′′), 39.14 (CH2N), 33.89 (CH2-
CO); MALDI-TOF MS m/z 881.8 [M + H]+, 903.2 [M + Na]+,
919.2 [M + K]+ obsd for C32H56N4O22S (880.31). A correct
elemental analysis for C32H56N4O22S (880.87) was not obtained.
1,3,5-[Tr is-N-[2-(6-d eoxy-6-N-[(r-D-m a n n op yr a n osyl)-
th ioca r ba m oyl]-N-[2-((6′′-d eoxy-1′′-O-m eth yl-r-D-m a n n o-
p yr a n os-6′′-yl)ca r ba m oyl)eth yl]a m in o-r-D-m a n n op yr a n -
osyloxyeth yl]]ben zen etr ia m id e (18). The amino-function-
alized trisaccharide mimetic 14 (8.10 mg, 0.0117 mmol),
trimesic acid 17 (1.70 mg, 0.008 mmol), HATU (15.30 mg, 0.04
mmol), and Hu¨nig’s base (DIPEA, 8 µL, 0.048 mmol) were
dissolved in dry DMF (3 mL) at rt under argon atmosphere.
The reaction mixture was stirred at 40 °C for 12 h and then
concentrated to dryness. The resulting crude product was a
pale yellow syrup that was subjected to gel permeation
chromatography on Bio-gel P-2 to afford the title cluster 18
(7.80 mg, 0.0035 mmol, 30%) as a white lyophilisate that
showed hygroscopic properties: [R]D ) -9° (c ) 0.8 in H2O);
1H NMR (500 MHz, D2O) δ 8.34 (s, 3H, 3 aryl-H), 5.48 (bs,
3H, 3 H-1′), 4.9 (bs, 3H, 3 H-1), 4.67 (s, 3H, 3 H-1′′), 3.95 (bs,
3H, 3 H-2), 3.90-3.82 (m, 12H, 3 NCHa, 3 H-2′′, 3 H-6a′, 3
H-2′), 3.82-3.70 (m, 6H, 3 H-3, 3 OCHa), 3.72-3.60 (m, 27H,
3 OCHb, 3 CHaNHCO, 3 H-6b, 3 H-6b′, 3 H-3′, 3 H-5, 3 H-3′′,
3 H-6a, 3 CHbNHCO), 3.60-3.45 (m, 18H, 3 H-6a′′, 3 NCHb, 3
H-5′′, 3 H-4′′, 3 H-4′, 3 H-4), 3.45-3.36 (m, 3H, 3 H-5′), 3.36-
3.3 (m, 3H, 3 H-6b′′), 3.3 (s, 9H, 3 OCH3), 2.67-2.47 (m, 6H,
3 CH2CO); 13C NMR (125.84 MHz, D2O): δ ) 183.40 (3 CdS),
175.94 (3 aryl-CONH), 174.24 (3 NHCO), 129.75 (3 aryl-C),
101.22 (3 C-1′′), 100.00 (3 C-1), 83.51 (3 C-1′), 77.92 (3 C-5′),
73.81 (3 C-3′′, 3 C-5), 71.01 (3 C-5′′, 3 C-4′′), 70.98 (3 C-3′),
70.76 (3 C-3), 70.33 (3 C-2′′), 70.26 (3 C-2, 3 C-2′), 68.45 (3
C-4′, 3 C-4), 67.07 (3 OCH2), 61.82 (3 C-6′), 55.07 (3 OCH3),
52.36 (3 C-6), 51.4 (3 NCH2), 40.43 (3 C-6′′), 40.1 (3 CH2NH),
33.78 (3 CH2CO); MALDI-TOF MS m/z 2227.8 [M + H]+,
2250.0 [M + Na]+, 2265.9 [M + K]+, obsd for C84H138N12O51S3
(2226.77). A correct elemental analysis for C84H138N12O51S3
(2228.25) was not obtained.
observed for C30H54N4O18S (790.31). Anal. Calcd for C30H54
-
N4O18S‚2H2O (826.87): C, 43.58; H, 7.07; N, 6.78; S, 3.88.
Found: C, 43.25; H, 7.14; N, 6.90; S, 3.98.
2-Am in oeth yl
6-Deoxy-6-N-[(r-D-m a n n op yr a n osyl)-
th ioca r ba m oyl]-N-[2-[(6′′-d eoxy-1′′-O-m eth yl-r-D-m a n n o-
pyr an os-6′′-yl)car bam oyl]eth yl]am in o-r-D-m an n opyr an o-
sid e (14). The Boc-protected trisaccharide mimetic 13 (120
mg, 0.151 mmol) was dissolved in a freshly prepared solution
of Me2S-CF3CO2H (1:2; 2 mL) at 0 °C and stirred at 0 °C for
3 h. Then the reaction mixture was concentrated. Traces of
trifluoroacetic acid which were left in the reaction mixture
were carefully neutralized at 0 °C with saturated NH3-H2O
solution (5 mL). Then lyophilization of the mixture afforded
crude amine 14 (104 mg, quant) as a pale yellow solid, which
was used for the synthesis of 16 and 18 without purification.
2-[(6′′′-Deoxy-1′′′-O-m et h yl-r-D-m a n n op yr a n os-6′′′-yl)-
ca r ba m oyl]et h yl 6-Deoxy-6-N-[(r-D-m a n n op yr a n osyl)-
th ioca r ba m oyl]-N-[2-[(6′′-d eoxy-1′′-O-m eth yl-r-D-m a n n o-
pyr an os-6′′-yl)car bam oyl]eth yl]am in o-r-D-m an n opyr an o-
sid e (16). The amine 14 (32 mg, 0.0463 mmol), the manno-
uronic acid derivative 15 (18 mg, 0.086 mmol), HATU (34.35
mg, 0.090 mmol), and Hu¨nig’s base (DIPEA, 0.025 mL, 0.15
mmol) were dissolved in dry DMF (5 mL) at rt under argon
atmosphere and stirred at 40 °C for 12 h. Then the reaction
mixture was concentrated, and the resulting pale yellow syrup
was subjected to gel permeation chromatography on Bio-gel
P-2 to afford 16 (29 mg, 0.032 mmol, 71%) as a white lyo-
philisate that showed hygroscopic properties: [R]D ) -3° (c )
Ack n ow led gm en t. This work was made possible
through the support of the Deutsche Forschungsge-
meinschaft DFG (SFB 470), the VW Foundation, and
the Karl-Ziegler-Stiftung. We are indebted to Dr. V.
Sinnwell (Hamburg) and Dr. C. Wolff (Kiel) for NMR
experiments and to Dipl.-Chem. M. Dubber for MALDI-
TOF measurements.
1
1.23 in H2O); H NMR (500 MHz, D2O) δ 5.51 (bs, 1H, H-1′),
4.87 (bs, 1H, H-1), 4.77 (s, 1H, H-1′′′), 4.68 (s, 1H, H-1′′), 4.16
(bs, 1H, NCHa), 4.5-3.8 (m, 7H, NCHb, H-5′′′, H-2′, H-2, H-2′′,
H-2′′′, H-6a′), 3.8-3.64 (m, 9H, H-6a, H-3, H-4′′′, H-6b, H-3′′′,
H-6b′, H-5, H-3′′, H-3′), 3.64-3.42 (m, 8H, H-6b′′, OCHa, H-4′′,
OCHb, H-4′, H-4, H-5′′, CHbN), 3.42-3.32 (m, 3H, H-5′, H-6a′′,
Abbr evia tion s u sed : HATU, O-(7-azabenzotriazol-
1-yl)-N ,N ,N ′,N ′-t et r a m et h ylu r on iu m h exa flu or o-
phosphate; DIPEA, diisopropylethylamine.
CHaN), 3.36, 3.32 (2s, 6H, 2 OCH3), 2.72 (m, 2H, CH2CO); 13
C
NMR (125.84 MHz, D2O) δ 183.43 (CdS), 174.39 (CONH),
171.77 (NHCO), 101.78 (C-1′′′), 101.26 (C-1′′), 100.03 (C-1),
J O005671U