First synthesis of "majoral-type" glycodendrimers bearing covalently bound α-D-mannopyranoside residues onto a hexachlocyclotriphosphazene core

Article abstract of DOI:10.1021/jo801850f

(Chemical Equation Presented) A short and efficient strategy for the first synthesis of "Majoral-Type" multivalent glycodendrimers bearing covalently bound α-D-mannopyranosides onto a cyclotriphosphazene scaffold assembled using single-step Sonogashira an

Full text of DOI:10.1021/jo801850f

First Synthesis of “Majoral-Type” Glycodendrimers Bearing
Covalently Bound r-D-Mannopyranoside Residues onto a
Hexachlocyclotriphosphazene Core
Mohamed Touaibia† and Rene´ Roy*
Department of Chemistry, UniVersite´ du Que´bec a` Montre´al, P.O. Box 8888, Succ. Centre-Ville, Montre´al,
Que´bec, Canada H3C 3P8
roy.rene@uqam.ca
ReceiVed August 21, 2008
A short and efficient strategy for the first synthesis of “Majoral-Type” multivalent glycodendrimers bearing
covalently bound R-D-mannopyranosides onto a cyclotriphosphazene scaffold assembled using single-
step Sonogashira and click chemistry is reported. New glycoclusters with valencies ranging from 6 to 18
and different epitope spatial arrangements were obtained. Cross-linking abilities of this series of
glycodendrimers were evaluated with the model lectin from CanaValia ensiformis (Concanavalin A).
The decameric mannoside 23, built around 19, was shown to be much faster in cross-linking the tetravalent
lectin Concanavalin A than the positive control, which is the polysaccharide mannan from yeast. The
new glycoconjugates reported may be promising tools as probes or effectors of biological processes
involving multivalent carbohydrate-binding proteins.
Introduction
host human tissues as the premise for bacterial infections. E.
coli is the main cause of urinary tract infections affecting the
bladder (cystitis).4,5 The importance of carbohydrate-binding
proteins6-9 or lectins in regulating biological systems is widely
The heavy use of antibiotics during the second half of the
last century has resulted in widespread bacterial resistance.1,2
Overcoming resistance requires the development of antibiotics
aimed at new targets of microorganisms.3 Bacteria such as
fimbriated Escherichia coli produce proteins at the tip of their
fimbriae (FimH) that recognize and bind to the mannosides of
(4) Hultgren, S. J.; Jones, C. H.; Normark, S. In Escherichia coli and
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*Corresponding author. Phone: 514-987-3000 x2546. Fax: 514-987-4054.
† Present address: Department of Chemistry and Biochemistry, Universite´ de
Moncton, Moncton, New Brunswick, Canada E1A 3E9. E-mail:
mohamed.touaibia@umoncton.ca.
(1) Henry, C. M. Chem. Eng. News 2000, 78, 41–58.
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10.1021/jo801850f CCC: $40.75 2008 American Chemical Society
Published on Web 11/07/2008

Synthesis of “Majoral-Type” Glycodendrimers
recognized and has inspired numerous efforts to understand and
manipulate these processes. However, carbohydrate-protein
interactions often occur with low-monomeric-binding affini-
ties.10-14 Consequently, biologically relevant interactions in-
volve multivalent interactions between the lectin and the multiple
carbohydrate ligands.15-25 Moreover, these multivalent interac-
tions have several advantages over monomeric ones and are
used often by nature to control a wide variety of cellular pro-
cesses.10,18,19 From these observations, glycodendrimers16,17,19-25
were synthesized to address fundamental aspects in multivalent
carbohydrate-protein interactions using well-defined and mono-
dispersed chemical entities. The “glycoside cluster effect” of
glycodendrimers is now firmly accepted and corresponds to an
affinity enhancement that is much greater than that expected
from a single binding event at a multiple-carbohydrate-recogni-
tion domain (CRD).11,12,14,25 Although several attempts to
quantify the effects of a multivalent presentation have been
reported,10-14,26-28 the detailed mechanism at the molecular
level still remains unclear, but a recent paper nicely described
the potential source of the increased binding using entropic
arguments and the “bind and slide” model.29 Thus, the design
of various types of clusters that can serve as inhibitors of
biological systems for medical use is still carried out on a very
empirical basis. A wide variety of dendrimers that is peripherally
functionalized with mannose units has been studied toward these
ends.16,21,22,24,25
of first-generation glycodendrimers bearing aryl R-D-mannopy-
ranoside residues assembled using single-step Sonoga-
shira and “click chemistry”. These glycodendrimers were found
to be excellent model ligands for the CanaValia ensiformis lectin
(Concanavalin A) and to be the best ligands known to date
toward E. coli K12 FimH with subnanomolar affinities.30,31
For high versatility and efficiency, the development of a
general approach to dendrimer functionalization should, there-
fore, employ a reaction that occurs with high yields, proceeds
under mild reaction conditions, and is compatible with es-
sentially all potential surface functional groups and internal
dendritic repeat units. The divergent method for dendrimer-
containing triazole unit(s) at the periphery can be facilitated by
fewer coupling reaction(s) between a terminal azide-function-
alized core and alkynes. In addition, the concept of click
chemistry has received enormous attention and has generated
considerable impact in organic synthesis since its simplification
in 200132-36 because of the high yields and the lack of
byproducts provided by click chemistry for “stitching” together
alkynes and azide cores. There have been ample examples since
of applications of click chemistry in the field of carbohydrate
chemistry.37
Because of our interest in developing new mannosylated
dendrimers as potential drug candidates for gastrointestinal and
urinary tract infections caused by E. coli,25,30 we became
involved in exploring an efficient cycloaddition reaction that
provides easy access to glycodendrimers. Here, we present the
syntheses of representative members of a new class of glyco-
dendrimers that are built on nontoxic cyclotriphosphazene cores.
Cyclophosphazene derivatives and polyorganophosphazenes are
encountered frequently in inorganic, organic, and high-polymer
chemistry.38 Allcock et al.39 reported that the syntheses of
polyphosphazene can be used as carriers for drug delivery
systems owing to their prominent biodegradability and biocom-
patibility. Cyclotriphosphazenes exhibit useful thermal and
chemical properties such as flame retardancy, oil repellance,
and biocompatibility. Inoue et al.40,41 reported the syntheses of
star-shaped amino acids with cyclotriphosphazene cores. Aziri-
In previous communications, we described our findings on
several families of mannosylated dendrimers.25,30 Pentaerythritol
and bis-pentaerythritol scaffolds were used for the preparation
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Amsterdam, 2007; Vol. 3, pp 781-829. (c) Chabre, Y. M.; Contino-Pe´pin, C.;
Placide, V.; Shiao, T. C.; Roy, R. J. Org. Chem. 2008, 73, 5602–5605.
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Bouckaert, J.; Roy, R. ChemMedChem 2007, 2, 1190–1201. (b) Touaibia, M.;
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R. T.; Nishimura, S.-I.; Page´, D.; Roy, R.; Lee, Y. C. ChemBioChem 2002, 3,
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Touaibia and Roy
SCHEME 1
dine group-substituted cyclophosphazenes were investigated as
biomedical products because of their strong antitumor activity.42
The antimicrobial and biological effects of some phosphazenes
on bacterial and yeast cells have been studied.43-45 A hexavalent
core has obvious advantages because it can accommodate a
greater number of dendrons and, hence, more functional groups
for a given dendrimer generation. Cyclotriphosphazene-centered
dendrimers are the landmark of the Majoral’s group46-50 and
are pioneers in cyclotriphosphazene core use in material
chemistry; however, to the best of our knowledge, those having
peripheral covalently bound sugar units are not described yet.
Taking advantage of the click ligation technique, we were able
to use terminal azide-functionalized hexachlorocyclotriphosp-
hazene cores to introduce mannosides into dendrimers in a
“clicked” divergent fashion. In systematic QSAR studies using
panels of mannoside-binding proteins, the above family of novel
glycodendrimers should complement nicely our understanding
of multivalent binding interactions.
Results and Discussion
Click chemistry has attracted much attention recently because
of its high specificity, quantitative yield, and tolerance to various
functional groups. Several papers have been published about
the synthesis of dendrimers through the click reaction in either
a convergent or a divergent manner.16,25,37 Moreover, transition
metal-catalyzed cross-couplings have proven to be powerful
tools for mild, highly efficient, carbon-carbon bond formations.
Among these processes, those involving palladium catalysis,
especially Sonogashira coupling of aryl halides,51 are particularly
useful for the syntheses of complex molecules owing to their
excellent levels of selectivity and high functional group compat-
ibility.Consequently,andonthebasisofpreviousexpertise,19,20,25,30the
efficient and systematic synthesis of a family of glycodendrimers
bearing mannopyranoside residues using multiple 1,3-cycloaddi-
tions and Sonogashira coupling is described herein.
reactive iodo aryl groups. The reaction of 2 with propargyl R-D-
mannopyranoside under Sonogashira coupling conditions affords
hexamannosylated product 4 in good yield. Deacetylation under
Zemple´n conditions (NaOMe, MeOH) gave unprotected hex-
amer 5 in a quantitative yield as shown in Scheme 1. The 31P
NMR of 5 shows that the phosphorus chemical shifts corre-
sponding to the cyclophosphazene skeleton are isochronous and
resonate at δ 11.75.
Trimethylsilylacetylene was next coupled to known 2 under
Sonogashira conditions52 to afford a 4-trimethylsilylethynylphe-
nyl-substituted core (6) in 96% yield. The acetylene was easily
deprotected by treatment with aqueous potassium hydroxide in
a methanol/ether mixture to afford 7 in 90% yield (Scheme 2).
Treatment of (4-acetylenylphenyl)cyclotriphosphazene 7 in
CuSO4-catalyzed click reaction conditions with 2-azidoethyl
2,3,4,6-tetra-O-acetyl-R-D-mannopyranoside 853,54 provided hex-
amer 10 in good yields after deacetylation (NaOMe, MeOH)
(Scheme 2).
As shown in Scheme 3, treatment of (4-acetylenylphenyl)-
cyclotriphosphazene 7 under Sonogashira coupling conditions
with 4-iodophenyl 2,3,4,6-tetra-O-acetyl-R-D-mannopyranoside
1155 provided a hexamer bearing aromatic aglycones 13 in good
yields after deacetylation (NaOMe, MeOH).
All attempts to prepare a uniform hexakis arylmethyl azide
intermediate from N3P3Cl6 (1) and the corresponding p-
azidomethyl phenol under various basic conditions (K2CO3,
Na2CO3, NaOH, NaH, etc.) failed, with the 31P NMR of 5
showing systematically more than one resonance. The reaction
mixtures resulted in inseparable mono- and polysubstituted
The target hexamer 5 was synthesized as depicted in Scheme
1. Treatment of N3P3Cl6 (1) with iodophenol under basic
conditions (K2CO3, acetone, 97%) afforded N3P3(O-C6H4-p-I)6
(2). Compound 2 is the primary starting material for the
assembly of the R-D-mannopyranosides, as it possesses six
(41) Inoue, K.; Miyahara, A.; Itaya, T. J. Am. Chem. Soc. 1997, 119, 6191–
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M.; Majoral, J.-P.; Reiser, O. Org. Lett. 2007, 9, 2895–2898. (c) Launay, N.;
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(52) The reaction mixture was heated between 30 and 40 °C only.
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9294 J. Org. Chem. Vol. 73, No. 23, 2008

Synthesis of “Majoral-Type” Glycodendrimers
SCHEME 2
SCHEME 3
azidocyclophosphazenes. However, using a different approach,
the multiple-substitution reaction involving the replacement of
chlorine atoms on 1 by the nucleophilic 4-formylphenoxy groups
has been successfully employed to provide the known hexaformyl-
phenoxy core 14a, which was next converted into the known
bromomethyl bearing core 15 (Scheme 4).56 The novel hexam-
eric azide 16 was thus obtained by conversion of hexabromi-
nated derivative 15, which under the above cycloaddition
conditions with propargyl mannoside 3 afforded the desired
hexamannosylated dendrimer 18 after deacetylation (73% over
two steps).
The syntheses of new kinds of glycoside clusters that will
open the route to novel glycodendrimer libraries exhibiting
varied sugars and densities should offer new opportunities for
J. Org. Chem. Vol. 73, No. 23, 2008 9295

Touaibia and Roy
SCHEME 4
a better understanding of multivalent carbohydrate-protein
recognition processes. In line with this idea, we report herein
the synthesis of the following decamannoside cluster 27
assembled using 1 as a propagating element and commercially
available bisphenol A (19) as the central core (Scheme 5). The
required bis-monosubstituted N3P3Cl5 fragment was introduced
onto the two hydroxyl groups of 19 by the monosubstitution of
N3P3Cl6 (1) to afford the decachloride 2057 in 74% yield using
BuLi as the base and excess 1. The 31P NMR of 20 showed
two resonances at δ 12.70 and 22.69. These signals cor-
responded to the two phosphine types within this cluster.
The terminal decachloride groups in 20 were converted into
iodoaryl groups by the same reaction described above for the
synthesis of 2. Introduction of the 10 R-D-mannopyranoside
groups was achieved by a multiple Sonogashira coupling, as
described above for the synthesis of 3, with 21 and propargyl
R-D-mannopyranoside (3) providing compound 22 in 78% yield.
The subsequent deacetylation under Zemple´n conditions gave
decamannoside dendrimer 23 in 94% yield.
For the next higher member of the family, the same synthetic
strategy was used as for dodecamer 27. Starting with the
hexabromomethyl scaffold 15 and the known tris-azido pen-
taerythritol 28,59 the octadecaazide 29 was obtained under a
multiple nucleophilic substitution in 68% yield (NaH, DMF,
100 °C, 10 h). The azido groups of cluster 29 were then treated
with propargylmannoside 3 using the above Cu(I)-catalyzed
click reaction (83% yield), followed by deacetylation to give
the corresponding octadecamannoside dendrimer 31 in 96%
yield (Scheme 7). Thus, the syntheses of both dodeca- and
octadecavalent-mannosylated dendrimers were efficiently realized.
The unprecedented glycoclusters prepared in this study
displayed some structural differences that are governed by the
cyclophosphazene and bisphenol A scaffolds as well as by the
number of mannosyl units and their relative orientation together
along with the ligation technique used for the mannoside
incorporation. These disparities offer a nice opportunity to
estimate their relative binding abilities while role modeling
multivalent carbohydrate-protein recognition in solution. Hence,
the whole ligand set including R-D-mannopyranoside dendrimers
with valencies ranging from 6 to 18 units was evaluated using
the well-established tetrameric phytohemeagglutinin Concanava-
lin A (Con A) from C. ensiformis.60 The relative ability of these
mannosylated dendrimers to act as cross-linking reagents was
investigated using a kinetic turbidimetric assay (nephelometry)
as previously used in similar circumstances.60 Each of the
Following our ongoing interest in the use of click chemistry
for the synthesis of mannosylated dendrimers,25,30 Scheme 6
describes the preparation of the dodecamannoside derivative 27.
The synthesis was initiated with dodecaazide 25, which was
prepared with multiple nucleophilic substitutions on each of the
bromines of 15 with the known diazide 24.58 Multiple CuSO4-
catalyzed click reactions with prop-2-ynyl R-D-mannopyranoside
3
53,54 provided dodecamer 27 in good yield after deacetylation
(Scheme 6).
(59) Wilson, E. R.; Frankel, M. B. J. Org. Chem. 1985, 50, 3211–3212.
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1351–1358. (e) Dam, T. K.; Roy, R.; Page´, D.; Brewer, C. F. Biochemistry 2002,
41, 1359–1363. (f) Dam, T. K.; Oscarson, S.; Roy, R.; Das, S. K.; Page´, D.;
Macaluso, F.; Brewer, C. F. J. Biol. Chem. 2005, 280, 8640–8646. (g) Roy, R.;
Page´, D.; Figueroa Perez, S.; Verez Bencomo, V. Glycoconjugate J. 1998, 15,
251–263. (h) Page´, D.; Roy, R. Glycoconjugate J. 1997, 14, 345–356.
(56) Chang, J. Y.; Ji, H. J.; Han, M. J.; Rhee, S. B.; Cheong, S.; Yoon, M.
Macromolecules 1994, 27, 1376–1380.
(57) Krishna, T. R.; Parent, M.; Werts, M. H. V.; Moreaux, L.; Gmouth, S.;
Charpak, S.; Caminade, A. M.; Majoral, J. P.; Blanchard-Desce, M. Angew.
Chem., Int. Ed. 2006, 45, 4645–4648.
(58) Katrizky, A. R.; Singh, S. K.; Meher, N. K.; Doskocz, J.; Suzuki, K.;
Jiang, R.; Sommen, G. L.; Ciaramitaro, D. A.; Steel, P. J. ARKIVOC (GainesVille,
FL, U.S.) 2006, (5), 43–62.
9296 J. Org. Chem. Vol. 73, No. 23, 2008

Synthesis of “Majoral-Type” Glycodendrimers
SCHEME 5
compounds and the lectin were tested at a concentration of 1
mg/mL using the polysaccharide yeast mannan as the positive
control. Rapidly and within a few minutes, insoluble cross-linked
complexes were formed as judged by the formation of precipi-
tated lattices within the wells following a turbid state (Figure
1). The time course of Con A precipitation by the corresponding
mannosylated dendrimers is illustrated in Figure 1.
Using Con A, dendrimers exhibiting the same hexameric
valency such as 5, 10, 13, and 18, differing by the mannoside
spacer arm (aryl or triazole), showed highly equivalent protein
binding properties compared to those of the positive control
yeast mannan. Hexamers 10 and 18, which were obtained under
click conditions, showed slightly faster cross-linking behavior
in comparison to that of the mannan control. The incorporation
of additional mannosyl units in dodecamer 27 and octadecamer
31 led, therefore, to merely statistical binding affinity enhance-
ments. This result supports the occurrence of a sliding process
that is optimal for the hexameric compound and suffers from
enthalpy-entropy compensation for more valent compounds.
The decamer-containing alkyne spacer 23 was shown to be
the fastest and more complete in forming the insoluble cross-
linked lattice. Interestingly, dodecamer 27 and octadecamer 31,
having a slightly longer spacer arm and more flexibility than
23, showed lower cross-linking potencies. The noticeable cross-
linking enhancement observed for 23 must be ascribed to the
existence of more favorable extended intersugar distances, thus
facilitating entry into the carbohydrate’s active site and permit-
ting a higher protein cross-linking ability. The special geometry
arrangement also can accommodate the clustering of a few
tetrameric lectins. Note, as previously described, these geom-
etries are designed purposely to prevent the simultaneous
binding of two mannosides from a single dendrimer to reach
the two mannoside binding sites of a single Con A tetramer
situated ∼65 Å apart.
Conclusion
The above set of assays are relevant in demonstrating the
relative protein binding properties of the persubstituted den-
drimers synthesized herein and further substantiate the useful-
ness of glycodendrimers in bioassays. The above mannosylated
dendrimers together with the analogous series are being evalu-
J. Org. Chem. Vol. 73, No. 23, 2008 9297

Touaibia and Roy
SCHEME 6
General Procedure for the Sonogashira Coupling Reaction. To
a solution of 4-iodophenyl derivative (0.068 mmol) in 3 mL of DMF
were added Pd(PPh3)2Cl2 (0.014 mmol, 3.5 mol%), CuI (0.021 mmol,
5 mol%), alkyne’s derivative (0.61 mmol), and triethylamine (1 mL).
The solution was stirred under nitrogen at 60 °C for 6 h. The solvent
and TEA were evaporated under reduced pressure. Water (10 mL)
and dichloromethane (30 mL) were added to the reaction mixture, and
the phases were separated. The aqueous phase was extracted with
dichloromethane (2 × 30 mL), and the combined organic phases were
washed with saturated aqueous NH4Cl (2 × 25 mL) and brine (2 ×
25 mL). The organic layers were dried over Na2SO4 and evaporated
under reduced pressure, leaving yellow oil. The residue was purified
by column chromatography eluting with dichloromethane to gradually
increase the polarity of MeOH:CH2Cl2 (10:90).
General Procedure for De-O-acetylation. An acetylated glyco-
cluster (0.1 mmol) was dissolved in dry MeOH (3 mL), and a solution
of sodium methoxide (1 M in MeOH, 0.5 equiv) was added. The
reaction mixture was stirred at room temperature until the starting
material disappeared. The solution was neutralized by the addition of
a cationic ion-exchange resin (H+), filtered, and washed with MeOH,
and then the solvent was removed in vacuo. The residue was
lyophilized to yield the fully deprotected glycocluster.
ated for their relative binding abilities with a panel of mannoside
binding proteins such as DC-SIGN, the FimH of E. coli, and
the Bcla lectin from Burkholderia cepacia.
Experimental Section
Organic azides are potentially explosive substances that can
decompose with the slightest input of energy from external sources
such as heat, light, and pressure; therefore, precautions must taken.
General Procedure for the Azide/Alkyne Cycloaddition
Catalyzed by CuI, Method A. To a 5 mL THF solution of azide
(0.1 mmol) and alkyne’s derivative (0.12 mmol per azide) were
added N,N-diisopropylethylamine (DIPEA) (0.2 mmol per azide)
and CuI (0.01 mmol per azide). The reaction mixture was then
stirred at room temperature for 12 h. TLC indicated the complete
consumption of the azide. After solvent evaporation, the crude
product was dissolved with ethyl acetate, washed with NH4Cl
solution (3 × 10 mL) and brine (3 × 10 mL), dried over Na2SO4,
and concentrated on a rotary evaporator. The residue was purified
by column chromatography eluting with dichloromethane to gradu-
ally increase the polarity of MeOH:CH2Cl2 (10:90).
General Procedure for the Click Reaction Catalyzed by CuSO4
in Water, Method B. A solution of an azide cluster (0.1 mmol),
mannose propargyl (0.12 mmol per azide), CuSO4 (1% per azide),
and sodium ascorbate (5% per azide) was dissolved in a 1:1 mixture
of water and THF (3 mL). After 12 h of reaction time, following the
general workup described above, the residue was purified by column
chromatography eluting with dichloromethane to gradually increase
the polarity of MeOH:CH2Cl2 (3:97).
Hexaiodide 2. A mixture of 1 (1 g, 2.87 mmol), 4-iodophenol (3.92
g, 17.81 mmol), and K2CO3 (5.16 g, 37.33 mmol) was refluxed in dry
acetone (20 mL) for 12 h. The solvent was removed in vacuo. The
residue was extracted with CH2Cl2 (3 × 25 mL). The organic phase
was washed with 15 mL of H2O and brine before being dried (Na2SO4)
and concentrated in vacuo. The obtained solid was recrystallized in
dichloromethane to afford 2 as a white solid in a 97% (4.03 g) yield
9298 J. Org. Chem. Vol. 73, No. 23, 2008

Synthesis of “Majoral-Type” Glycodendrimers
SCHEME 7
(known but never characterized).61 Mp: 95-97 °C. Rf: 0.18 (ethyl
acetate:hexanes, 10:90). 1H NMR (300 MHz, CDCl3, 25 °C): δ 7.52
(d, J (H,H) ) 8.6 Hz, 12H; Har), 6.62 (d, J (H,H) ) 8.6 Hz, 12H;
Har). 13C NMR (75 MHz, CDCl3, 25 °C): δ 149.9 (Car), 138.6 (CHar),
123.01 (CHar), 89.3 (Car). 31P NMR (121 MHz, CDCl3, 25 °C): δ 9.03
(s). ESI-MS m/z: calcd for C36H24I6O6N3P3 + (H+), 1449.51. Found
m/z: 1449.52.
Hexamannoside 5. From 4 (100 mg, 0.033 mmol) and sodium
methoxide (25 µL from 1 M solution in MeOH) in 3 mL of methanol,
and after 4 h of reaction time following the general procedure described
above, deprotected glycocluster 5 (66 mg, 99%) was obtained as white
20
foam. Rf: 0.22 (CH3CN:H2O, 7:3). [R]D ) +29.3 (c ) 1.0 in
CH3OH). 1H NMR (300 MHz, DMSO-D6, 25 °C): δ 7.40 (d, J (H,H)
) 8.2 Hz, 12H; Har), 6.93 (d, J (H,H) ) 8.2 Hz, 12H; Har), 4.85 (s,
br, 18H; H-1, OCH2CC), 4.55-4.52 (m, 6H; H-2), 4.47-4.43 (m,
12H; H3, H-4), 3.69-3.63 (m, 6H; H-6a), 3.47-3.35 (m, 12H; H-6b,
H-5). 13C NMR (75 MHz, DMSO-D6, 25 °C): δ 149.7 (OCar), 133.3
(CHar), 120.7 (CHar), 119.3 (CCar), 98.4 (C-1), 86 (CarCC), 84.4
(CarCC), 74.4 (C-2), 70.9 (C-5), 70.1 (C-3), 66.8 (C-4), 61.1 (C-6),
53.7 (CH2CC). 31P NMR (121 MHz, DMSO-D6, 25 °C): δ 11.75 (s).
HRMS m/z: calcd for C90H102N3O42P3 + (H+), 1990.5223. Found m/z:
1990.5183.
Peracetylated Hexamannoside 4. From 2 (100 mg, 0.069 mmol),
prop-2-ynyl 2,3,4,6-tetra-O-acetyl-R-D-mannopyranoside (3) (192 mg,
0.49 mmol), PdCl2(PPh3)2 (17 mg, 0.024 mmol, 5 mol%), and CuI
(10 mg, 0.052 mmol, 10 mol %) dissolved in DMF (4 mL) and Et3N
(1 mL), and after 6 h of reaction time following the general procedure
described above, glycocluster 3 (169 mg, 82%) was obtained as a white
20
foam. Rf: 0.21 (ethyl acetate:hexanes, 80:20). [R]D ) +39.1 (c )
1.0 in CHCl3). 1H NMR (300 MHz, CDCl3, 25 °C): δ 7.31 (d, J (H,H)
) 8.6 Hz, 12H; Har), 6.91 (d, J (H,H) ) 8.6 Hz, 12H; Har), 5.37-5.29
(m, 18H; H-2, H-3, H-4), 5.12 (d, J (H,H) ) 1.4 Hz, 6H; H-1),
4.52-4.51 (m, 12H; OCH2CC), 4.31 (dd, J (H,H) ) 12.2, 4.8 Hz,
6H; H-6a), 4.15-4.06 (m, 12H; H-6b, H-5), 2.16-1.99 (4s, 72H;
COCH3). 13C NMR (75 MHz, CDCl3, 25 °C): δ 170.6, 169.9, 169.8,
169.6 (COCH3), 150.5 (OCar), 133.2 (CHar), 120.8 (CHar), 119.2 (CCar),
96.1 (C-1), 86.2 (CarCC), 83.5 (CarCC), 69.4 (C-2), 68.9 (C-6, C-4),
65.9 (C-3), 62.3 (C-5), 55.75 (CH2CC), 20.8 (COCH3), 20.7 (COCH3),
20.6 (COCH3), 20.6 (COCH3). 31P NMR (121 MHz, CDCl3, 25 °C):
δ 8.1 (s). HRMS m/z: calcd for C138H150N3O66P3 + (2Na+), 1521.8735.
Found m/z: 1521.8752.
Compound 6. From 2 (100 mg, 0.069 mmol), trimethylsilylacety-
lene (49 mg, 0.49 mmol), PdCl2(PPh3)2 (17.5 mg, 0.025 mmol, 5 mol
%), and CuI (10 mg, 0.052 mmol, 10 mol %) dissolved in DMF (3
mL) and Et3N (1 mL), and after 6 h of reaction time at 40 °C following
the general procedure described above, glycocluster 6 (84 mg, 96%)
was obtained as a yellow solid. Rf: 0.21 (ethyl acetate:hexanes, 10:
90). Mp: 72-74 °C. 1H NMR (300 MHz, CDCl3, 25 °C): δ 7.33 (d,
J (H,H) ) 8.6 Hz, 12H; Har), 6.76 (d, J (H,H) ) 8.6 Hz, 12H; Har),
0.27 (s, 54H; Si(CH3)3). 13C NMR (75 MHz, CDCl3, 25 °C): δ 150.2
(OCar), 133.3 (CHar), 120.9 (CHar), 120.3 (CCar), 103.9 (CarCC), 94.5
(CarCC), -0.2 (SiCH3). 31P NMR (121 MHz, CDCl3, 25 °C): δ 7.36
(s). HRMS m/z: calcd for C66H78N3O6P3Si6 + (H+), 1270.3797. Found
m/z: 1270.3839.
(61) Allcock, H. R.; Ngo, D. C.; Parvez, M.; Visscher, K. B. Inorg. Chem.
1994, 33, 2090–2102.
J. Org. Chem. Vol. 73, No. 23, 2008 9299

Touaibia and Roy
128.2 (CHar), 126.6 (CdCH), 121.6 (CHar), 120.9 (Car), 99.9 (C-1),
74.2 (C-2), 70.8 (C-3), 70 (C-5), 66.7 (C-4), 64.8 (OCH2CH2N), 61.1
(C-6), 49.5 (OCH2CH2N). 31P NMR (121 MHz, DMSO-D6, 25 °C):
δ 13.91 (s). HRMS m/z: calcd for C96H122N21O42P3 + (2H+),
1166.8629. Found m/z: 1166.8661.
Peracetylated Haxamannoside 12. From 7 (50 mg, 0.059 mmol),
4-iodophenyl 2,3,4,6-tetra-O-acetyl-R-D-mannopyranoside (11) (227
mg, 0.41 mmol), PdCl2(PPh3)2 (13 mg, 0.018 mmol, 5 mol%), and
CuI (7 mg, 0.036 mmol, 10 mol%) dissolved in DMF (4 mL) and
Et3N (1 mL), and after 6 h of reaction time following the general
procedure described above, glycocluster 12 (140 mg, 70%) was
20
obtained as a white foam. Rf: 0.21 (ethyl acetate:hexanes, 80:20). [R]D
) +38.1 (c ) 1.0 in CHCl3). 1H NMR (300 MHz, CDCl3, 25 °C): δ
7.45 (d, J (H,H) ) 8.5 Hz, 12H; Har), 7.41 (d, J (H,H) ) 8.5 Hz,
12H; Har), 7.06 (d, J (H,H) ) 8.5 Hz, 12H; Har), 6.96 (d, J (H,H) )
8.5 Hz, 12H; Har), 5.57-5.53 (m, 18H; H-2, H-3, H-4), 5.45 (d, J
(H,H) ) 1.4 Hz, 6H; H-1), 4.28 (dd, J (H,H) ) 12.6, 5.7 Hz, 6H;
H-6a), 4.08-4.04 (m, 12H; H-6b, H-5), 2.21, 2.06, 2.04, 1.96 (s, 72H;
COCH3). 13C NMR (75 MHz, CDCl3, 25 °C): δ 170.4, 169.9, 169.8,
169.7 (COCH3), 155.4 (OCar), 145.2 (OCar), 133 (CHar), 132.8 (CHar),
120.9 (CHar), 120.4 (Car), 117.6 (Car), 116.4 (CHar), 95.5 (C-1), 89
(CC), 87.8 (CC), 69.2 (C-2), 69.2 (C-5), 68.7 (C-4), 65.8 (C-3), 62
(C-6), 20.8, 20.7, 20.6, 20.4 (COCH3). 31P NMR (121 MHz, CDCl3,
25 °C): δ 7.54 (s). HRMS m/z: calcd for C168H162N3O66P3 + (Na+ +
H+), 1696.9295. Found m/z: 1696.9297.
FIGURE 1. Turbidimetric analysis (microprecipitation) of Con A with
hexamers 5 (9), 10 (2), 13 (O), and 18 (b), decamer 23 (×), dodecamer
27 (0), octadecamer 31 (4), and yeast mannan (|) used as the positive
control. Measurements were done in phosphate-buffered saline (PBS)
at 1 mg mL-1 using a microplate reader at 25 °C and are the average
of triplicate values.
Compound 7. To a solution of 6 (50 mg, 0.039 mmol) in 2.5 mL
of diethyl ether were added 2.5 mL of methanol and 1 mL of an
aqueous 10% sodium hydroxide solution. After 10 min of stirring at
room temperature, the reaction mixture was neutralized with 1 M HCl
solution. The organic layer was separated, and the aqueous layer was
back-extracted with diethyl ether. The combined organic layers were
washed with brine and water, dried over Na2SO4, and concentrated to
afford, after column chromatography (acetate:hexanes, 6:94) purifica-
tion, 29.7 mg (90%) of 7 as a white solid. Mp: 128-130 °C. Rf: 0.23
(ethyl acetate:hexanes, 10:90). 1H NMR (300 MHz, CDCl3, 25 °C): δ
7.35 (d, J (H,H) ) 8.5 Hz, 12H; Har), 6.84 (d, J (H,H) ) 8.5 Hz,
12H; Har), 3.1 (s, 6H; CCH). 13C NMR (75 MHz, CDCl3, 25 °C): δ
150.4 (OCar), 133.5 (CHar), 120.9 (CHar), 119.3 (CCar), 82.5 (CarCC),
77.6 (CarCC). 31P NMR (121 MHz, CDCl3, 25 °C): δ 7.32 (s). HRMS
m/z: calcd for C48H30N3O6P3 + (H+), 838.1420. Found m/z: 838.1415.
Peracetylated Hexamannoside 9. Compound 7 (50 mg, 0.059
mmol), 2′-azidoethyl 2,3,4,6-tetra-O-acetyl-R-D-mannopyranoside (8)
(187 mg, 0.45 mmol), CuSO4 ·5H2O (12 mg, 0.05 mmol), and sodium
ascorbate (2.73 mg, 0.045 mmol) were dissolved in THF:H2O (1:1)
(5 mL). After 12 h of reaction time, the mixture was treated following
the general procedure described above, and glycocluster 9 (167 mg,
84%) was obtained as a white solid. Mp: 118-120 °C Rf: 0.19 (MeOH:
Hexamannoside 13. Compound 12 (40 mg, 0.012 mmol) and
sodium methoxide (5 µL from 1 M solution in MeOH) in 3 mL of
methanol were stirred for 4 h, and the mixture was treated following
the general procedure described above. Deprotected glycocluster 13
(26 mg, 93%) was obtained as a white foam. Rf: 0.18 (H2O:CH3CN,
20
1
3:7). [R]D ) +32.7 (c ) 1.0 in CH3OH). H NMR (300 MHz,
DMSO-D6, 25 °C): δ 7.48 (d, J (H,H) ) 7.8 Hz, 12H; Har), 7.41 (d,
J (H,H) ) 7.8 Hz, 12H; Har), 7.04 (d, J (H,H) ) 7.8 Hz, 12H; Har),
6.96 (d, J (H,H) ) 7.8 Hz, 12H; Har), 4.47 (s br, 6H; H-1), 3.83 (s br,
6H; H-2), 3.69-3.65 (m, 6H; H-3), 3.58-3.42 (m, 12H; H-4, H-6a),
3.33-3.22 (m, 12H; H-6b, H-5). 13C NMR (75 MHz, DMSO-D6, 25
°C): δ 156.6 (OCar), 149.3 (OCar), 132.9 (CHar), 132.8 (CHar), 120.9
(CHar), 120 (Car), 116.9 (Car), 115.3 (CHar), 98.6 (C-1), 89.6 (CC),
87.1 (CC), 75.1 (C-2), 70.5 (C-5), 69.9 (C-4), 66.5 (C-3), 60.9 (C-6).
31P NMR (121 MHz, DMSO-D6, 25 °C): δ 12.96 (s). HRMS m/z:
calcd for C120H114N3O42P3 + (H+), 2362.6162. Found m/z: 2362.6161.
Compound 14a. Compound 1 (500 mg, 1.44 mmol), 4-hydroxy-
benzaldehyde (1.1 g, 9 mmol), and K2CO3 (2.5 g, 18.08 mmol) were
stirred in dry acetone (15 mL) for 12 h, and the mixture was treated
following the general procedure described for 2 synthesis. Silica gel
chromatography (EtOAc:hexanes, 1:1) provided 14a (984 mg, 80%)
20
1
CH2Cl2 5:95). [R]D ) +49.6 (c ) 1.0 in CHCl3). H NMR (300
MHz, CDCl3, 25 °C): δ 7.95 (s, 6H; CHdC), 7.61 (d, J (H,H) ) 8.4
Hz, 12H; Har), 7.02 (d, J (H,H) ) 8.4 Hz, 12H; Har), 5.24-5.16 (m,
18H; H-2, H-3, H-4), 4.88 (d, J (H,H) ) 1.4 Hz, 6H; H-1), 4.68 (s br,
12H; CH2-N), 4.21-4.09 (m, 18H; H-6a, OCH2CH2), 4.0-3.95 (m,
12H; H-6b, H-5), 2.12, 2.06, 2.02, 1.97 (s, 72H; COCH3). 13C NMR
(75 MHz, CDCl3, 25 °C): δ 170.5, 169.9, 169.8, 169.6 (COCH3), 150.1
(CdCH), 146.9 (OCar), 127.5 (CHar), 126.9 (CdCH), 121.3 (CHar),
121.2 (Car), 97.2 (C-1), 69.2 (C-2), 68.4 (C-5), 66 (C-3, C-4), 65.5
(OCH2), 62.1 (C-6), 49.7 (CH2N), 20.8, 20.7, 20.6, 20.4 (COCH3).
31P NMR (121 MHz, CDCl3, 25 °C): δ 9.39 (s). HRMS m/z: calcd
for C144H168N21O66P3 + (2H+), 1670.9897. Found m/z: 1670.9903.
Hexamannoside 10. Compound 9 (109 mg, 0.031 mmol) and
sodium methoxide (16 µL from 1 M solution in MeOH) in 3 mL of
methanol were stirred for 4 h, and the mixture was treated following
the general procedure described above. Deprotected glycocluster 10
(70 mg, 95%) was obtained as a white foam. Rf: 0.18 (H2O:CH3CN,
1
as a white solid. Mp: 92-94 °C. Rf: 0.30 (EtOAc:hexanes, 1:1). H
NMR (300 MHz, CDCl3, 25 °C): δ 9.94 (6H, COH), 7.72 (d, J (H,H)
) 8.5 Hz, 12H; Har), 7.13 (d, J (H,H) ) 8.5 Hz, 12H; Har). 13C NMR
(75 MHz, CDCl3, 25 °C): δ 190.31 (CO), 154.32 (Car), 133.59 (CHar),
131.24 (CHar), 121.07 (Car). 31P NMR (121 MHz, CDCl3, 25 °C): δ
6.02 (s). HRMS m/z: calcd for C42H30N3O12P3 + (H+), 862.1115.
Found m/z: 862.1105.
Compound 14b. To a solution of compound 14a (500 mg, 0.58
mmol) in a mixture of THF and methanol (50 mL, 1:l) was added
sodium borohydride (140 mg, 3.75 mmol) at room temperature. The
reaction mixture was stirred for 12 h at the same temperature. After
evaporation of the solvents, the resulting solids were recrystallized from
90% ethanol to give 14b (440 mg, 87%) as a white solid. Mp:
1
215-217 °C. Rf: 0.28 (MeOH:CH2Cl2, 1:1). H NMR (300 MHz,
DMSO, 25 °C): δ 7.18 (d, J (H,H) ) 7.7 Hz, 12H; Har), 6.79 (d, J
(H,H) ) 7.7 Hz, 12H; Har), 5.23 (br s, 6H, CH2OH), 4.45 (d, 12H, J
(H,H) ) 4.9 Hz, CH2OH). 13C NMR (75 MHz, CDCl3, 25 °C): δ
148.61 (Car), 139.43 (CHar), 127.66 (CHar), 120.11 (Car), 62.24 (CH2).
31P NMR (121 MHz, DMSO, 25 °C): δ 12.9 (s). HRMS m/z: calcd
for C42H42N3O12P3 + (H+), 874.2054. Found m/z: 874.2043.
20
1
3:7). [R]D ) +37.2 (c ) 1.0 in CH3OH). H NMR (300 MHz,
DMSO-D6, 25 °C): δ 8.41 (s, 6H; CHdC), 7.49 (d, J (H,H) ) 8.6
Hz, 12H; Har), 7.03 (d, J (H,H) ) 8.6 Hz, 12H; Har), 4.72-4.70 (m,
12H; OCH2CH2N), 4.64 (s br, 6H; H-1), 4.49-4.45 (m, 12H;
OCH2CH2N), 4.03-3.99 (m, 6H; H-2), 3.78-3.83 (m, 6H; H-3),
Compound 15. 14b (170 mg, 0.19 mmol) was dissolved in a
mixture of 48% HBr (3 mL) and concentrated H2SO4 (0.5 mL), and
the solution was refluxed for 8 h. Precipitates were collected by
3.63-3.54 (m, 12H; H-4, H-6a), 3.39-3.16 (m, 12H; H-6b, H-5). 13
C
NMR (75 MHz, DMSO-D6, 25 °C): δ 149.3 (CHdC), 145.3 (OCar),
9300 J. Org. Chem. Vol. 73, No. 23, 2008

Synthesis of “Majoral-Type” Glycodendrimers
filtration and washed with a copious amount of water (300 mL) until
neutral. The product was isolated by column chromatography on silica
gel (20% ethyl acetate in hexane) to give 15 (190 mg, 78%) as a white
solid. Mp: 147-149 °C. 1H NMR (300 MHz, CDCl3, 25 °C): δ 7.25
(d, J (H,H) ) 8.2 Hz, 12H; Har), 6.90 (d, J (H,H) ) 8.2 Hz. 12H;
Har), 4.49 (s, 6H, CH2Br). 13C NMR (75 MHz, CDCl3, 25 °C): δ
150.13 (Car), 133.54 (CHar), 130.34 (CHar), 121.17 (Car), 32.82 (CH2).
31P NMR (121 MHz, DMSO, 25 °C): δ 7.82 (s). HRMS m/z: calcd
for C42H36Br6N3O6P3 + (H+), 1245.6989. Found m/z: 1245.6927.
Hexaazide 16. NaN3 (116 mg, 1.78 mol) was added to a solution
of 15 (1 g, 0.84 mol) in DMF (3 mL) under N2, and the resulting
mixture was heated to 100 °C. After 10 h, the solution was cooled,
poured into water (250 mL), and extracted with Et2O (50 mL and
then 4 × 20 mL). Because of the potential explosiveness of the azides,
the organic fractions were combined, dried (Na2SO4), and concentrated
in vacuo at <40 °C. Purification by column chromatography (eluent,
CH2Cl2:hexanes, 2:8) gave 12 (73 mg, 96%) as a white solid. Mp:
125-126 °C. Rf: 0.28 (EtOAc:hexanes, 3:7). IR (NaCl): γ 2097 cm-1
(N3). 1H NMR (300 MHz, CDCl3, 25 °C): δ 7.16 (d, J (H,H) ) 8.5
Hz, 12H; Har), 6.97 (d, J (H,H) ) 8.5 Hz, 12H; Har), 4.32 (s, 12H;
CH2N3). 13C NMR (75 MHz, CDCl3, 25 °C): δ 150.3 (OCar), 132.2
(CHar), 129.3 (CHar), 121.2 (Car). 31P NMR (121 MHz, CDCl3, 25
°C): δ 8.04 (s). HRMS m/z: calcd for C42H36N21O6P3 + (H+),
1024.2443. Found m/z: 1024.2458.
Peracetylated Hexamannoside 17. Hexaazide 16 (50 mg, 0.05
mmol), prop-2-ynyl 2,3,4,6-tetra-O-acetyl-R-D-mannopyranoside (3)
(142 mg, 0.36 mmol), N,N-diisopropylethylamine (65 µL, 0.37 mmol),
and CuI (7 mg, 0.036 mmol) were dissolved in THF (5 mL), and after
12 h of reaction time following the general procedure described above,
compound 17 (127 mg, 78%) was obtained as a white foam. Rf: 0.17
(MeOH:CH2Cl2, 4:96). [R]D20 ) +38.1 (c ) 1.0 in CHCl3). 1H NMR
(300 MHz, CDCl3, 25 °C): δ 7.69 (s, 6H; CHdC), 7.07 (d, J (H,H)
) 8.1 Hz, 12H; Har), 6.87 (d, J (H,H) ) 8.1 Hz, 12H; Har), 5.51 (s,
12H; CCH2N), 5.33-5.20 (m, 18H; H-4, H-3, H-2), 4.95 (d, J (H,H)
) 1.4 Hz, 6H; H-1), 4.83 (d, J (H,H) ) 12.5 Hz, 6H; OCH), 4.65 (d,
J (H,H) ) 12.5 Hz, 6H; OCH), 4.29 (dd, J (H,H) ) 4.8, 12.5 Hz, 6H;
H-6a), 4.11-4.07 (m, 12H; H-6b, H-5), 2.13, 2.10, 2.02, 1.96 (s, 72H;
COCH3). 13C NMR (75 MHz, CDCl3, 25 °C): δ 170.6, 169.9, 169.9,
169.6 (COCH3), 150.3 (OCar), 143.7 (CHdC), 131.7 (CHar), 129.1
(CHar), 123.4 (CHdC), 121.3 (Car), 96.8 (C-1), 69.3 (C-2), 69 (C-3),
68.6 (C-5), 65.9 (C-4), 62.2 (CH2OCH), 60.8 (C-6), 53.2 (CCH2N),
20.8, 20.7, 20.6, 20.6 (COCH3). 31P NMR (121 MHz, CDCl3, 25 °C):
δ 7.89 (s). HRMS m/z: calcd for C144H168N21O66P3 + (2H+),
1670.9896. Found m/z: 1670.9880.
(2 × 20 mL) and dried over Na2SO4. The residue was purified by
silica gel chromatography (dissolved in a minimal amount of CH2Cl2
and eluted with 2% EtOAc in hexanes) to provide 20 (452 mg, 74%)
as a white solid. Mp: 98-100 °C. Rf: 0.28 (EtOAc:hexanes, 5:95). 1H
NMR (300 MHz, CDCl3, 25 °C): δ 7.24-7.14 (m, 10H; Har), 1.67 (s,
6H; C(CH3)2). 13C NMR (75 MHz, CDCl3, 25 °C): δ 148.7 (OCar),
147.3 (C(CH3)2Car), 128.2 (CHar), 120.8 (CHar), 42.5 (C(CH3)2Car),
30.7 (C(CH3)2Car). 31P NMR (121 MHz, CDCl3, 25 °C): δ 22.69 (d,
J (P,P) ) 59.8 Hz), 12.7 (t, J (P,P) ) 59.8 Hz). HRMS m/z: calcd for
C15H14Cl10N6O2P6 + (H+), 846.6562. Found m/z: 846.6555.
Decaiodide 21. Compound 20 (89 mg, 0.1 mmol), 4-iodophenol
(276 mg, 17.81 mmol), and K2CO3 (347 g, 37.33 mmol) were refluxed
in dry acetone (10 mL) for 12 h, and the mixture was treated following
the general procedure described for 2 synthesis. Silica gel chroma-
tography (EtOAc:hexanes, 4:6) provided 21 (225 mg, 80%) as a white
solid. Mp: 78-80 °C. Rf: 0.30 (EtOAc:hexanes, 1:1). 1H NMR (300
MHz, CDCl3, 25 °C): δ 7.52-7.46 (m, 20H; Har), 7.08 (d, J (H,H) )
8.7 Hz, 4H; Har), 6.78 (d, J (H,H) ) 8.7 Hz, 4H; Har), 6.67 (d, J (H,H)
) 8.7 Hz, 8H; Har), 6.59 (d, J (H,H) ) 8.7 Hz, 12H; Har), 1.69 (s, 6H;
C(CH3)2). 13C NMR (75 MHz, CDCl3, 25 °C): δ 150.1, 148.7 (OCar),
147.2 (C(CH3)2Car), 138.6, 127.8, 123.2, 123, 120.1 (CHar), 89.2 (ICar),
42.3 (C(CH3)2Car), 31 (C(CH3)2Car). 31P NMR (121 MHz, CDCl3, 25
°C): δ 9.04-8.96 (s br). HRMS m/z: calcd for C75H54I10N6O12P6 +
(H+), 2686.2746. Found m/z: 2686.2695.
Peracetylated Decamannoside 22. From 21 (100 mg, 0.04 mmol),
prop-2-ynyl 2,3,4,6-tetra-O-acetyl-R-D-mannopyranoside (3) (172.6 mg,
0.44 mmol), PdCl2(PPh3)2 (16 mg, 0.023 mmol, 5 mol%), and CuI (9
mg, 0.05 mmol, 10 mol%) dissolved in DMF (4 mL) and Et3N (1
mL), and after 6 h of reaction time following the general procedure
described above, glycocluster 22 (153 mg, 78%) was obtained as a
20
white foam. Rf: 0.18 (ethyl acetate:hexanes, 8:2). [R]D ) +31.6 (c
) 1.0 in CHCl3). 1H NMR (300 MHz, CDCl3, 25 °C): δ 7.31-7.28
(m, 20H; Har), 7.07 (d, J (H,H) ) 8.8 Hz, 8H; Har), 6.93-6.84 (m,
20H; Har), 5.38-5.27 (m, 30H; H-4, H-3, H-2), 5.12 (d, J (H,H) )
1.4 Hz, 10H; H-1), 4.52-4.46 (m, 20H, OCH2CC), 4.34-4.27 (m,
10H; H-6a), 4.15-4.06 (m, 20H; H-6b, H-5), 2.15, 2.09, 2.03, 1.98
(s, 120H; COCH3), 1.63 (s, 6H; C(CH3)2). 13C NMR (75 MHz, CDCl3,
25 °C): δ 170.5, 169.8, 169.8, 169.6 (COCH3), 150.5, 147.2 (OCar),
133.2, 127.8, 120.9, 120.8 (CHar), 120.2, 119 (CCar), 96 (C-1), 86.2
(CarCC), 83.4 (CarCC), 69.4 (C-2), 68.9 (C3, C-4), 65.9 (C-5), 55.5
(CH2CC), 42.2 (C(CH3)2Car), 30.8 (C(CH3)2Car), 20.8, 20.6, 20.7, 20.6
(COCH3). 31P NMR (121 MHz, CDCl3, 25 °C): δ 8.33 (s). HRMS
m/z: calcd for C245H264N6O112P6 + (2H+), 2634.6859. Found m/z:
2634.6775.
Hexamannoside 18. Compound 17 (105 mg, 0.03 mmol) and
sodium methoxide (16 µL from 1 M solution in MeOH) in 3 mL of
methanol were stirred for 4 h, and the mixture was treated following
the general procedure described above. Deprotected glycocluster 18
(68.8 mg, 94%) was obtained as a white foam. Rf: 0.28 (H2O:CH3CN,
3:7). [R]D ) +39.7 (c ) 1.0 in CH3OH). H NMR (300 MHz,
DMSO-D6, 25 °C): δ 8.18 (s, 6H; CHdC), 7.17 (d, J (H,H) ) 8.4
Hz, 12H; Har), 6.81 (d, J (H,H) ) 8.4 Hz, 12H; Har), 5.57 (s, 12H;
CCH2N), 4.78 (s br, 6H; H-1), 4.70-4.47 (m, 30H; H-4, H-3, H-2,
CH2OCH), 3.67-3.54 (m, 6H; H-6a), 3.46-3.34 (m, 12H; H-6b, H-5).
13C NMR (75 MHz, DMSO-D6, 25 °C): δ 149.4 (OCar), 143.8
(CHdC), 133.1 (CHar), 129.5 (CHar), 124.3 (CHdC), 120.7 (Car), 99
(C-1), 74.1 (C-2), 70.8 (C-5), 70.1 (C-3), 66.9 (C-4), 61.2 (CH2OCH),
59 (C-6), 52 (CCH2N). 31P NMR (121 MHz, DMSO-D6, 25 °C): δ
12.81 (s). HRMS m/z: calcd for C96H122N21O42P3 + (2H+), 1166.8629.
Found m/z: 1166.8622.
Decamannoside 23. Compound 22 (100 mg, 0.02 mmol) and
sodium methoxide (10 µL from 1 M solution in MeOH) in 3 mL of
methanol were stirred for 4 h, and the mixture was treated following
the general procedure described above. Deprotected glycocluster 23
(64 mg, 94%) was obtained as a white foam. Rf: 0.12 (H2O:CH3CN,
3:7). [R]D ) +30.6 (c ) 1.0 in CH3OH). H NMR (300 MHz,
DMSO-D6, 25 °C): δ 7.41-7.34 (m, 20H; Har), 7.09-7.06 (m, 8H;
Har), 6.92-6.79 (m, 20H; Har), 4.85 (s br, 10H; H-1), 4.66-4.47 (m,
50H; H-4, H-3, H-2, CH2CC), 3.63-3.34 (m, 30H; H-6, H-5), 1.65
(s, 6H; C(CH3)2). 13C NMR (75 MHz, DMSO-D6, 25 °C): δ 149.7,
147.2 (OCar), 133.2, 127.8, 120.7 (CHar), 119.9, 119.1 (CCar), 98.4
(C-1), 85.9 (CarCC), 84.4 (CarCC), 69.3 (C-2), 70.9 (C-4), 70.1 (C-3),
66.8 (C-5), 61.1 (C-6), 53.7 (CH2CC), 41.8 (C(CH3)2Car), 30.2
(C(CH3)2Car). 31P NMR (121 MHz, CDCl3, 25 °C): δ 8.24 (s). HRMS
m/z: calcd for C165H184N6O44P6 + (2H+), 1794.4746. Found m/z:
1794.4705.
20
1
20
1
Decachloride 20. n-BuLi solution in hexanes (2.3 M, 0.7 mL, 1.63
mmol) was added dropwise to a solution of 2,2-bis(4-hydroxyphenyl)-
propane (bisphenol A, 19) (164 mg, 0.71 mmol) in THF (15 mL) at
-78 °C. The white mixture was added to a solution of 1 (1.25 g, 3.6
mmol) in THF (3 mL) at 0 °C. The resulting pale yellow solution was
allowed to reach room temperature and stirred for 2 h. The solution
was then dried in vacuo, and the addition of hexane led to the
precipitation of the residual 1. After filtration, CHCl3 (25 mL) was
added, and the solution was washed with brine (2 × 20 mL) and H2O
Dodecaazide 25. To a stirred suspension of NaH (60% in mineral
oil, 17.5 mg, 0.73 mmol) in DMF (4 mL) at room temperature was
added dropwise diazide 15 (52 mg, 0.36 mmol). The mixture was
stirred for 30 min prior to the dropwise addition of 15 (50 mg, 0.04
mmol) in DMF (1 mL). The solution was stirred at room temperature
for 12 h followed by quenching with H2O (5 mL). The layers were
separated, and the aqueous layer was extracted with ether (3 × 10
mL). The combined organic layers were washed with H2O (3 × 10
mL) and brine (3 × 10 mL), dried over Na2SO4, and concentrated on
J. Org. Chem. Vol. 73, No. 23, 2008 9301

Touaibia and Roy
a rotary evaporator. The residue was purified by silica gel chroma-
tography (dissolved in a minimal amount of CH2Cl2 and eluted with
30% EtOAc in hexanes) to provide 25 as a yellow oil (42.2 mg, 66%).
Rf: 0.20 (CH2Cl2). IR (film): 2100 cm-1. 1H NMR (300 MHz, CDCl3,
25 °C): δ 7.22 (d, J (H,H) ) 8.5 Hz, 12H; Har), 6.95 (d, J (H,H) )
8.5 Hz, 12H; Har), 4.63 (s, 12H; PhCH2O), 3.68 (q, J (H,H) ) 5.2 Hz,
6H; OCH(CH2)2), 3.39 (d, J (H,H) ) 5.2 Hz, 24H; CH2N3). 13C NMR
(75 MHz, CDCl3, 25 °C): δ 150.3 (OCar), 133.9 (CHar), 128.9 (CHar),
121 (Car), 77.1 (PhCH2O), 71.8 (CHCH2N), 51.7 (CH2N3). 31P NMR
(121 MHz, CDCl3, 25 °C): δ 8.03 (s). HRMS m/z: calcd for
C60H66N39O12P3 + (H+), 1618.5038. Found m/z: 1618.5028.
68.7 (CCH2O), 51.4 (CH2N3), 44.6 (CCH2N3). 31P NMR (121 MHz,
CDCl3, 25 °C): δ 7.87 (s). HRMS m/z: calcd for C72H84N57O12P3 +
(H+), 2032.7000. Found m/z: 2032.9663.
Peracetylated Octadecamannoside 30. From the polyazide 29 (73
mg, 0.036 mmol), prop-2-ynyl 2,3,4,6-tetra-O-acetyl-R-D-mannopy-
ranoside (3) (313 mg, 0.81 mmol), N,N-diisopropylethylamine (142
µL, 0.81 mmol), and CuI (16 mg, 0.08 mmol) dissolved in THF (5
mL), and after 12 h of reaction time following the general procedure
described above, glycocluster 30 (296 mg, 83%) was obtained as a
white foam. Rf: 0.19 (MeOH:CH2Cl2, 5:95). [R]D20 ) +32.3 (c ) 1.0
1
in CHCl3). H NMR (300 MHz, CDCl3, 25 °C): δ 7.64 (s, 18H;
Peracetylated Dodecaazide 26. From dodecaazide 25 (19.5 mg,
0.012 mmol), prop-2-ynyl 2,3,4,6-tetra-O-acetyl-R-D-mannopyranoside
(3) (70 mg, 0.18 mmol), N,N-diisopropylethylamine (32 µL, 0.18
mmol), and CuI (3.5 mg, 0.018 mmol) dissolved in THF (5 mL), and
after 12 h of reaction time following the general procedure described
above, glycocluster 26 (63 mg, 84%) was obtained as a white foam.
Rf: 0.29 (MeOH:CH2Cl2, 5:95). [R]D20 ) +44.3 (c ) 1.0 in CHCl3).
1H NMR (300 MHz, CDCl3, 25 °C): δ 7.80 (s, 12H; CHdC), 7.08
(d, J (H,H) ) 8.4 Hz, 12H; Har), 6.85 (d, J (H,H) ) 8.4 Hz, 12H;
Har), 5.34-5.24 (m, 24H; H-4, H-3), 5.23-5.19 (m, 12H; H-2), 4.95
(s br, 12H; H-1), 4.80 (d, J (H,H) ) 12.2 Hz, 12H; OCHN), 4.65 (d,
J (H,H)) 12.2 Hz, 12H; OCHN), 4.50-4.45 (m, 42H; PhCH2O,
OCHCH2, OCH(CH2)2), 4.28 (dd, J (H,H) ) 4.6, 12.3 Hz, 12H; H-6),
4.11-4.08 (m, 24H; H-6b, H-5), 2.11, 2.10, 2.01, 1.95 (s, 144H;
COCH3). 13C NMR (75 MHz, CDCl3, 25 °C): δ 170.6, 170, 169.9,
169.6 (COCH3), 150.3 (OCar), 143.3 (CHdC), 133.8 (CHar), 129.3
(CHar), 125 (CHdC), 121 (Car), 96.7 (C-1), 75.4 (OCH(CH2N)2), 71.7
(PhCH2O), 69.3 (C-2), 69 (C-3), 68.6 (C-5), 65.7 (C-4), 62.2
(CH2OCH), 60.5 (C-6), 50.4 (OCH(CH2N)2), 20.8, 20.7, 20.6, 20.6
(COCH3). 31P NMR (121 MHz, CDCl3, 25 °C): δ 8.09 (s). HRMS
m/z: calcd for C264H330N39O132P3 + (4H+), 1563.7453. Found m/z:
1563.7375.
CHdC), 6.85 (d, J (H,H) ) 8.1 Hz, 12H; Har), 6.59 (d, J (H,H) ) 8.1
Hz, 12H; Har), 4.85 (s, 12H; PhCH2O), 4.81-4.79 (m, 54H; H-4, H-3,
H-2), 4.68 (s br, 18H; H-1), 4.49 (s br, 36H; CCH2N) 4.33 (d, J (H,H)
) 12.2 Hz, 18H; 2 COCH), 4.17 (d, J (H,H) ) 12.2 Hz, 18H; 2
COCH), 4.03-4.98 (m, 12H; OCH2C), 3.82-3.80 (m, 18H; H-6a),
3.64-3.61 (m, 36H; H-6b, H-5), 1.95, 1.62, 1.57, 1.51 (s, 216H;
COCH3). 13C NMR (75 MHz, CDCl3, 25 °C): δ 170.5, 169.91, 169.7,
169.6 (COCH3), 150.3 (OCar), 142.8 (CHdC), 134.2 (CHar), 129.4
(CHar), 126.5 (CHdC), 120.8 (Car), 96.6 (C-1), 69.3 (C-2, PhCH2O),
68.9 (C-3), 68.6 (C-5), 65.8 (C-4), 62.2 (CH2OCH), 60.2 (C-6), 49.2
(CCH2N), 45.9 (CCH2N), 20.8, 20.7, 20.6, 20.5 (COCH3). 31P NMR
(121 MHz, CDCl3, 25 °C): δ 7.45 (s). HRMS m/z: calcd for
C
378H480N57O192P3 + (3H+), 2996.3033. Found m/z: 2996.3022.
18-mer 31. Compound 30 (175 mg, 0.02 mmol) and sodium
methoxide (10 µL from 1 M solution in MeOH) in 3 mL of methanol
were stirred for 4 h, and the mixture was treated following the general
procedure described above. Deprotected glycocluster 31 (111 mg, 96%)
20
was obtained as a white foam. Rf: 0.22 (H2O:CH3CN, 3:7). [R]D
)
+49.7 (c ) 1.0 in CH3OH). 1H NMR (300 MHz, DMSO-D6, 25 °C):
δ 8.15 (s, 18H; CHdC), 7.27 (d, J (H,H) ) 8.2 Hz, 12H; Har), 6.94
(d, J (H,H) ) 8.2 Hz, 12H; Har), 4.71 (s br, 18H; H-1), 4.66-4.47
(m, 102H; H-4, H-3, H-2, PhCH2O, CCH2N), 3.65-3.35 (m, 102H;
3 OCH2CH, OCH2C, H-6, H-5). 13C NMR (75 MHz, DMSO-D6, 25
°C): δ 149.6 (OCar), 143.6 (CHdC), 134.9 (CHar), 129.4 (CHar), 126.6
(CHdC), 120.4 (Car), 99.2 (C-1), 74.2 (C-2, PhCH2O), 70.9 (C-3),
70.2 (C-5), 66.9 (C-4), 61.3 (CH2OC, CCH2OCH), 60.3 (C-6), 49.2
(CCH2N), 45.9 (CCH2N). 31P NMR (121 MHz, DMSO-D6, 25 °C): δ
12.36 (s). HRMS m/z: calcd for C234H340N57O120P3 + (4H+), 1490.2861.
Found m/z: 1490.2882.
Dodecamannoside 27. Compound 26 (30 mg, 0.005 mmol) and
sodium methoxide (3 µL from 1 M solution in MeOH) in 3 mL of
methanol were stirred for 4 h, and the mixture was treated following
the general procedure described above. Deprotected glycocluster 27
(17.5 mg, 96%) was obtained as a white foam. Rf: 0.17 (H2O:CH3CN,
20
1
3:7). [R]D ) +44.7 (c ) 1.0 in CH3OH). H NMR (300 MHz,
DMSO-D6, 25 °C): δ 7.77 (s, 12H; CHdC), 6.65 (d, J (H,H) ) 8.4
Hz, 12H; Har), 6.48 (d, J (H,H) ) 8.4 Hz, 12H; Har), 4.70 (s br, 12H;
H-1), 4.70-4.47 (m, 102H; PhCH2O, H-4, H-3, H-2, CH2OCH,
OCH(CH2)2, OCH(CH2)2), 3.69-3.66 (m, 12H; H-6a), 3.47-3.41 (m,
24H; H-6b, H-5). 13C NMR (75 MHz, DMSO-D6, 25 °C): δ 148.7
(OCar), 143.2 (CHdC), 133.6 (CHar), 129.4 (CHar), 125.4 (CHdC),
120.2 (Car), 98.9 (C-1), 75.1 (OCH(CH2N)2), 72.5 (PhCH2O), 70.8
(C-2), 70.1 (C-5), 69.5 (C-3), 66.9 (C-4), 60.4 (CH2OCH), 59.1 (C-
6), 50.6 (OCH(CH2N)2). 31P NMR (121 MHz, DMSO-D6, 25 °C): δ
11.15 (s). HRMS m/z: calcd for C168H237N39O84P3 + (3H+), 1412.4889.
Found m/z: 1412.4885.
Turbidimetric Analysis. Turbidimetry experiments were performed
in microtitration plates where 100 mL/well of stock Con A solution,
prepared from 1 mg mL-1 PBS, was mixed with 100 mL/well of a
mannosylated cluster solution and incubated at room temperature for
12 min (Figure 1). The turbidity of the solutions was monitored by
reading the optical density (O.D.) at 490 nm at regular time intervals
until no noticeable changes could be observed. Each test was done in
triplicate.
Acknowledgment. This work was carried out with financial
support from CORPAQ (Quebec, Canada) and the Natural
Sciences and Engineering Research Council of Canada (NSERC).
Octadecaazide 29. From NaH (60% in mineral oil, 35 mg, 1.46
mmol), triazide 28 (152 mg, 0.72 mmol), and hexabromo derivative
15 (100 mg, 0.08 mmol), and following the procedure described above
for 25 synthesis, compound 29 (109 mg, 68%) was obtained as a
1
yellow oil. Rf: 0.22 (CH2Cl2). IR (film): 2103 cm-1. H NMR (300
1
Supporting Information Available: H NMR, 13C NMR,
and 31P NMR spectra of all new compounds. This material is
available free of charge via the Internet at http://pubs.acs.org.
MHz, CDCl3, 25 °C): δ 7.16 (d, J (H,H) ) 8.5 Hz, 12H; Har), 6.98
(d, J (H,H) ) 8.5 Hz, 12H; Har), 4.45 (s, 12H; PhCH2O), 3.36-3.31
(m, 48H; OCH2C, 3 CH2N3). 13C NMR (75 MHz, CDCl3, 25 °C): δ
150.4 (OCar), 134.2 (CHar), 128.8 (CHar), 120.9 (Car), 72.7 (PhCH2O),
JO801850F
9302 J. Org. Chem. Vol. 73, No. 23, 2008