A simple iterative method for the synthesis of β-(1→6)- glucosamine oligosaccharides

Article abstract of DOI:10.1016/j.carres.2013.01.008

Poly-N-acetylglucosamine (PNAG) saccharides are an important constituent of bacterial biofilms, such as those produced by Staphylococcus aureus. We have developed a simple two-step iterative method for the synthesis of β-(1→6)-glucosamine oligosaccharides that are structurally similar to PNAG. We illustrate the method with the formation of a pentasaccharide. The key building block is an orthogonally protected N-trifluoroacetamido thioglycoside donor that was added in succession to a glycosyl acceptor, enabling efficient glycosylation of the growing chain. In the second step of the iterative cycle, this building block is quantitatively deprotected at the C-6-hydroxyl position, ready for the next saccharide addition. Building from an azido-functionalised GlcNAc monosaccharide acceptor, the pentasaccharide was synthesised in seven steps in an overall yield of 25%.

Full text of DOI:10.1016/j.carres.2013.01.008

Accepted Manuscript
A simple iterative method for the synthesis of β-(1→6)-glucosamine oligosac‐
charides
Lucy G. Weaver, Yogendra Singh, Joanne T. Blanchfield, Paul L. Burn
PII:
S0008-6215(13)00022-0
DOI:
http://dx.doi.org/10.1016/j.carres.2013.01.008
CAR 6381
Reference:
To appear in:
Carbohydrate Research
Received Date:
Revised Date:
Accepted Date:
26 November 2012
9 January 2013
11 January 2013
Please cite this article as: Weaver, L.G., Singh, Y., Blanchfield, J.T., Burn, P.L., A simple iterative method for the
synthesis of β-(1→6)-glucosamine oligosaccharides, Carbohydrate Research (2013), doi: http://dx.doi.org/10.1016/
j.carres.2013.01.008
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A simple iterative method for the synthesis of β-(1→6)-glucosamine
oligosaccharides
Lucy G. Weaver†, Yogendra Singh†, Joanne T. Blanchfield†*, Paul L. Burn‡*
† The School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD 4072, Australia
‡Centre for Organic Photonics & Electronics, University of Queensland, St Lucia, QLD 4072, Australia
Corresponding Authors. Email: j.blanchfield@uq.edu.au, p.burn2@uq.edu.au.
Graphical Abstract
Abstract
Poly-N-acetylglucosamine (PNAG) saccharides are an important constituent of bacterial
biofilms, such as those produced by Staphylococcus aureus. We have developed a simple two-
step iterative method for the synthesis of β-(1→6)-glucosamine oligosaccharides that are
structurally similar to PNAG. We illustrate the method with the formation of a pentasaccharide.
The key building block is an orthogonally protected N-trifluoroacetamido thioglycoside donor
that was added in succession to a glycosyl acceptor, enabling efficient glycosylation of the
growing chain. In the second step of the iterative cycle, this building block is quantitatively
1

deprotected at the C-6-hydroxyl position, ready for the next saccharide addition. Building from
an azido-functionalized GlcNAc monosaccharide acceptor, the pentasaccharide was synthesised
in seven steps in an overall yield of 25%.
Keywords
N-Acetyl-D-glucosamine (GlcNAc); β-(1→6)-Glucosamine oligosaccharides; Staphylococcus
aureus; Poly-N-acetylglucosamine (PNAG); Biofilm, Polysaccharide Intercellular Adhesin
(PIA).
1. Introduction
Glucosamine units are often incorporated into or form a major constituent of polysaccharides
that play a critical role in a variety of biological systems and processes.1, 2 Of particular clinical
significance is the role β-(1→6)-poly-N-acetyl-D-glucosamine (PNAG) plays in the virulence of
bacterial biofilms produced by coagulase negative strains such as Staphylococcus aureus (S.
aureus) and Staphylococcus epidimeridis.3-5 S. aureus in particular has manifested itself as a
world-wide health problem, primarily due to the emergence of antibiotic resistant bacterial
strains (e.g. MRSA), and this has sparked global interest in developing alternative therapies to
antibiotics, such as a vaccine.6-11 Approaches utilizing β-(1→6)-glucosamine polysaccharides
conjugated with a carrier protein have successfully elicited protective anti-PNAG antibodies
during in vivo studies.12-14 This was demonstrated most recently by Maira-Litrán et al. who
showed that the deactylated form of a PNAG analogue bound to another S. aureus antigen,
clumping factor A, produced a bivalent vaccine that elicited protective antibodies in mice.13
2

In order to reproducibly generate such constructs it would be advantageous to have a reliable
synthetic methodology for the preparation of oligosaccharides, rather than having to isolate and
purify the complex carbohydrates from the bacterial specimen itself.3, 15, 16 Despite over 50 years
of research in this field, there are only a handful of reliable synthetic methodologies developed
for the synthesis of β-(1→6)-glucosamine polysaccharides.1, 12, 16-27 Perhaps the simplest method
for generating such oligosaccharides is the technique of acid reversion, that has been reported for
the synthesis of oligomers between two and six monosaccharide units in length.17, 18 Despite the
simplicity of using an unprotected sugar to rapidly generate the oligosaccharides, the method is
inherently inefficient as it produces an uncontrolled mixture of short chain carbohydrates with
consequent problems of separation and purification.
The alternative methods all require protecting group strategies for the production of β-(1→6)-
glucosamine polysaccharides. Of these methodologies, most involve the use of activated
glycosyl donors possessing the phthalimido (Phth) protecting group at the 2-amino-2-deoxy
position.16, 19-27 This was most recently demonstrated by Yudina et al. who successfully
synthesised, via a convergent blockwise process, a nonasaccharide that had varying degrees of
N-acetylation at the 2-amino-2-deoxy position of the final saccharides.20 Although N-
trifluoroacetyl glucosamine derivative have been used previously in other areas of carbohydrate
synthesis,1 no PNAG-derived oligosaccharide synthesis of this nature utilises solely this
protecting group throughout its methodology. We selected this group for blocking the 2-amino-
2-deoxy position during our synthesis because of its ease of attachment and subsequent
deprotection (if required), as well as its ability to generate β-selective glycosidic linkages. In the
interest of simplifying the synthetic methodology for the preparation of β-(1→6)-glucosamine
3

polysaccharides, we herein report a two-step iterative approach to a β-(1→6)-glucosamine
pentasaccharide, using a selectively protected thioglycoside donor as the key building block.
2. Results and Discussion
The β-(1→6)-glucosamine oligosaccharides were built from the starting glycosyl acceptor 3,
which was an azido-functionalized GlcNAc monosaccharide acceptor, protected with benzoyl
groups at the C-3 and C-4 hydroxyl positions. The azide group was placed at the reducing end of
3 to enable conjugation of the oligosaccharides to other structures if required. This could be
achieved using cycloaddition chemistry to an alkyne moiety or via reduction of the azide
followed by further conjugation of the resultant amine.
Surprisingly, although the existence of compound 3 was reported in 2001,28 there is no
experimental or characterisation data relating to its identity and purity. For this reason, we have
included a synthetic route to compound 3, which was achieved in two steps from the starting
material 2-acetamido-2-deoxy-β-D-glucopyranosyl azide 1 (Figure 1).29 The C-6 hydroxyl
position of this glycosyl azide was selectively protected with the tert-butyldiphenylsilyl
(TBDPS) protecting group, before benzoylation with benzoyl chloride to give 2 in 84% yield for
the two-step process.
Scheme 1. Synthesis of the glycosyl acceptor 3. (a) TBDPSCl, DMAP, pyridine; BzCl, DMAP,
pyridine, CH2Cl2; (b) TBAF (1.0 M in THF), HOAc, THF.
4

Deprotection of intermediate 2 to give acceptor 3 was achieved quantitatively by treatment of the
silyl-protected monosaccharide with tetra-n-butylammonium fluoride in the presence of acetic
acid. Use of acetic acid in this reaction, giving a slightly acidic reaction medium, prevented
formation of unwanted side products arising from migration of the neighbouring acyl groups.
The syntheses of the glycosyl capping donor 6 and key building block 7 were completed in three
steps from ethyl 2-trifluoroacetamido-3,4,6-tri-O-acetyl-1-thio-2-deoxy-β-D-glucopyranoside
4.30 Acetylated thioglycoside 4 was deprotected following the Zémplen de-O-acetylation
procedure31 to generate intermediate 5. Treatment with benzoyl chloride furnished the per-
benzoylated glycosyl donor 6 in 92% yield, whilst an alternate treatment with TBDPSCl
followed by benzoyl chloride, resulted in the synthesis of the glycosyl donor 7 (87%).
Scheme 2. Preparation of glycosyl donors 6 and 7. (a) NaOMe, MeOH; (b) TBDPSCl, DMAP,
pyridine; (c) BzCl, DMAP, pyridine, CH2Cl2.
To illustrate the iterative glycosylation process, donor 7 was used for chain extension and donor
6 for capping the growing oligosaccharide built from acceptor 3. The reason for terminating
each oligosaccharide with donor 6 rather than the orthogonally protected donor 7 was to ensure
that the number of different protecting groups on the final oligosaccharide was kept to an
absolute minimum, as well as the number of synthetic steps required for protecting group
5

removal (if pertinent). The glycosylation process is depicted in Scheme 3 and a summary of the
yields is given in Table 1. The disaccharide 8 was formed by reacting glycosyl acceptor 3 with
donor 6, in the presence of N-iodosuccinimide (NIS) and a catalytic amount of trimethylsilyl
trifluoromethanesulfonate (TMSOTf).
Scheme 3. Illustration of the two-step iterative cycle for the synthesis of β-(1→6)-glucosamine
oligosaccharides. (a) 7, NIS, TMSOTf, CH2Cl2; (b) TBAF, HOAc, THF; (c) 6, NIS, TMSOTf,
CH2Cl2.
To build the trisaccharide 11, acceptor 3 was reacted with donor 7 under the same coupling
conditions to give 9. The TBDPS protecting group on 9 was then removed with tetra-n-
butylammonium fluoride under acidic conditions to form 10, which was then capped with donor
6. It is important to note that at each stage of oligosaccharide growth, the deprotection step
6

occurred in a quantitative yield. Trisaccharide 11 was thus formed in a 71% yield over the three
steps. To form the tetra- and pentasaccharides there were one and two deprotection/coupling
cycles with 7 respectively, before capping with 6. Importantly, the yields of the glycosylation
reactions were all in the range of 65%-95%, which in some cases is significantly higher than
those previously reported (Table 1).
Table 1.a Yields corresponding to the relevant β-(1→6)-glucosamine oligosaccharides.
Yield (%)b
Donor Acceptor Glycoside
R1
n
TBDPS
0
83
65
70
86
95
77
68
7
7
7
6
6
6
6
3
9
TBDPS
TBDPS
Bz
1
2
0
1
2
3
10
13
3
12
15
8
Bz
10
13
16
11
14
17
Bz
Bz
a n = 0, disaccharide; n = 1, trisaccharide; n = 2, tetrasaccharide; n = 3, pentasaccharide. b yield of coupling reaction
only.
The overall yield of 25% for the pentasaccharide was achieved in seven simple steps from the
starting building units. While the overall yield is not significantly higher than some of the best
previously published procedures,19, 20 our method has the advantage that the synthesis of each of
the starting monosaccharides is straightforward and short, being prepared in only 1-3 steps from
the unprotected monosaccharides 1 and 5, respectively. Although it was not necessary for our
7

research purposes to deprotect these oligosaccharides, this could be achieved by using basic
conditions such as 0.1 M aqueous sodium hydroxide in acetone, which removes both the O-
benzoyl and N-trifluoroacetyl protecting groups in the one pot.1 This again emphasises the
simplicity of the protecting group strategy employed in this synthetic methodology.
In summary, we have reported an efficient two-step iterative route for preparing β-(1→6)-
glucosamine oligosaccharides using N-trifluoroacetamido protected thioglycoside donors. The
utilization of the N-trifluoroacetyl substituted donor in this case provides a simple, much-needed
alternative to the N-phthalimido-protected donors utilised in many methodologies to date.
3. Experimental Section
3.1 General Methods
Materials obtained commercially were reagent grade unless otherwise stated. Anhydrous
solvents were distilled under nitrogen or argon prior to use, according to the established
procedures.32 Thin layer chromatography (TLC) was performed on Kieselgel 60 F254 plates
(Merck, aluminium backed) and compounds were visualised either by treatment with anisidine
phthalate dip followed by heating, or under a UV lamp. Melting points were measured on a
Büchi Melting Point apparatus and are uncorrected. Elemental analyses were carried out on a
Carlo Erba NA 1500 Elemental Analyser. Optical rotations were measured at the sodium D line
(589 nm) at the ambient temperature using a 1 mL quartz cell with a 10 cm path length, using a
Jasco P-2000 polarimeter. UV-Visible absorption measurements were recorded on a Perkin
Elmer Lambda 35 Spectrometer. NMR spectra were recorded on either a Bruker Avance 400 or
500 MHz spectrometer equipped with Topspin software. Proton (1H) and carbon (13C)
assignments were made using DEPT, COSY, TOCSY (100 ms mixing time), HSQC and HMBC
8

experiments. Spectra of compounds run in deuterated chloroform (CDCl3) or a mixture of
CDCl3 and deuterated methanol (CD3OD) were referenced to residual chloroform at δ 7.26 ppm
for 1H NMR and δ 77.0 ppm for 13C NMR. All reported coupling constants (J values) are three
bond H-H couplings (3J) unless otherwise stated. High-resolution mass spectrometry (HRMS)
was performed on a Bruker microTOF-Q (quadrupole – Time of Flight) mass spectrometer with
a Bruker ESI source, in positive electrospray ionization mode. Agilent ESI Tunemix was used as
an external calibration for accurate mass measurements. Infrared spectra of neat samples were
recorded on a Perkin-Elmer Spectrum 100 FT-IR Spectrometer with a diamond/ZnSe universal
ATR attachment.
3.2 2-Acetamido-6-O-tert-butyldiphenylsilyl-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl
azide (2)
A solution of 2-acetamido-2-deoxy-β-D-glucopyranosyl azide 129 (0.38 g, 1.55 mmol), TBDPSCl
(0.44 mL, 1.70 mmol), DMAP (9.50 mg, 77.4 µmol), and anhydrous pyridine (10 mL) was
stirred under nitrogen at room temperature for 3 d. The reaction mixture was cooled in an ice-
water bath and then BzCl (0.54 mL, 4.65 mmol) in anhydrous CH2Cl2 (10 mL) was added to the
stirred solution. The reaction mixture was allowed to warm to room temperature before being
stirred at room temperature for 6 h. The reaction mixture was diluted with EtOAc (200 mL) and
washed with water (80 mL) followed by satd NaHCO3 (80 mL). The organic layer was dried
over anhydrous MgSO4, filtered and the solvent removed. The residue was purified by column
chromatography over silica gel using an Et2O:light petroleum mixture (60%) that included
0.25% Et3N as the eluent. The main fraction was collected and the solvent removed to give 2 as
a white solid: 0.90 g, 84 %; mp 83-85 °C; [α]D23-74.6° (c 0.59, CH2Cl2); Rf 0.23 (100% Et2O);
λabs [CH2Cl2]/nm : 228 (log ε/M-1cm-1, 4.58), 264 (3.52), 271 (3.54), 283 (3.40); IR (neat); v
9

3284 (NH), 2114 (N3), 1727 and 1265 (ester), 1067 and 690 (C-O, C-F), 1025 (Si-O), 701 cm-1
(Ar); 1H NMR (CDCl3; 400 MHz) δ 7.96-7.94 (m, 2H, Ar-H), 7.87-7.85 (m, 2H, Ar-H), 7.72-
7.70 (m, 2H, Ar-H), 7.58-7.49 (m, 4H, Ar-H), 7.42-7.28 (m, 8H, Ar-H), 7.20-7.17 (m, 2H,
Ar-H), 5.83 (d, 1H, JNH,2 9.2 Hz, NHCOCH3), 5.75 (t, 1H, J4,3 9.6, J4,5 9.2 Hz, H-4), 5.61 (t, 1H,
J3,2 10.4, J3,4 9.6 Hz, H-3), 4.77 (d, 1H, J1,2 9.2 Hz, H-1), 4.25 (q, 1H, J2,3 10.4, J2,1 9.2, J2,NH
9.2 Hz, H-2), 3.89-3.80 (m, 3H, H-5, H-6), 1.90 (s, 3H, NHCOCH3), 1.04 (s, 9H, C(CH3)3); 13C
NMR (CDCl3; 100 MHz) δ 170.5 (NHCOCH3), 167.1 (OCOAr), 164.8 (OCOAr), 135.6
(Ar-CH), 135.5 (Ar-CH), 133.6 (Ar-CH), 133.3 (Ar-CH), 132.9 (Ar-C-), 132.8 (Ar-C-), 129.9
(Ar-CH), 129.69 (Ar-CH), 129.66 (Ar-CH), 129.6 (Ar-CH), 129.1 (Ar-C-), 128.6 (Ar-C-), 128.5
(Ar-CH), 128.4 (Ar-CH), 127.7 (Ar-CH), 127.6 (Ar-CH), 88.6 (C-1), 77.0 (C-5), 73.2 (C-3),
68.4 (C-4), 62.2 (C-6), 54.5 (C-2), 26.6 (C(CH3)3), 23.2 (NHCOCH3), 19.2 (C(CH3)3); Anal.
Calcd for C38H40N4O7Si: C, 65.88; H, 5.82; N, 8.09. Found: C, 66.03; H, 5.87; N, 8.11.
3.3 2-Acetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl azide (3)
A solution of compound 2 (1.06 g, 1.53 mmol) in anhydrous THF (20 mL), HOAc (0.87 mL,
15.3 mmol) and TBAF (1.0 M in THF; 7.63 mL, 7.63 mmol) was stirred at room temperature for
24 h. The reaction mixture was diluted with Et2O (200 mL) and washed with satd NH4Cl
solution (20 mL). The organic layer was dried over anhydrous MgSO4, filtered and the solvent
removed. The residue was purified by column chromatography over silica gel using Et2O
(100%) as the eluent. The main fraction was collected and the solvent removed to give 3 as a
white solid: 0.69 g, quant.; mp 72-74 °C; [α]D21-124.3° (c 0.09, CH2Cl2); Rf 0.23 (100% Et2O);
λabs [CH2Cl2]/nm : 233 (log ε/M-1cm-1, 4.51), 275 (3.57), 283 (3.48), 315 (3.33); IR (neat); v
3281 (NH), 2115 (N3), 1722 and 1248 (ester), 1068 and 690 (C-O, C-F), 707 cm-1 (Ar); 1H NMR
(CDCl3; 500 MHz) δ 7.93-7.90 (AA’BB’C, 4H, Ar-H), 7.52-7.48 (AA’BB’C, 2H, Ar-H), 7.37-
10

7.33 (AA’BB’C, 4H, Ar-H), 6.01 (d, 1H, JNH,2 8.9 Hz, NHCOCH3), 5.80 (t, 1H, J3,2 10.7, J3,4
9.5 Hz, H-3), 5.51 (t, 1H, J4,5 9.8, J4,3 9.7 Hz, H-4), 4.98 (d, 1H, J1,2 9.3 Hz, H-1), 4.18 (q, 1H,
J2,3 10.6, J2,1 9.1, J2,NH 9.1 Hz, H-2), 3.90-3.85 (m, 2H, H-5, H-6a), 3.74 (dd, 1H, 2J6b,6a 12.9, J6b,5
4.5 Hz, H-6b), 1.89 (s, 3H, NHCOCH3); 13C NMR (CDCl3; 125 MHz) δ 170.6 (NHCOCH3),
166.7 (OCOAr), 165.9 (OCOAr), 133.73 (Ar-CH), 133.66 (Ar-CH), 129.8 (Ar-CH), 128.5
(Ar-CH, Ar-C-), 128.4 (Ar-C-), 88.7 (C-1), 76.6 (C-5), 72.4 (C-3), 69.0 (C-4), 61.2 (C-6), 54.5
+
(C-2), 23.2 (NHCOCH3). HRMS: Calcd for C22H22N4NaO7 [M+ Na]+ m/z = 477.1381. Found:
477.1373.
3.4 Ethyl 2-trifluoroacetamido-1-thio-2-deoxy-β-D-glucopyranoside (5)
A solution of ethyl 2-trifluoroacetamido-3,4,6-tri-O-acetyl-1-thio-2-deoxy-β-D-glucopyranoside
430 (0.11 g, 0.26 mmol) in MeOH (2 mL) was treated with NaOMe (cat.; 2.0 mg of Na° in 1 mL
of MeOH) and stirred at room temperature for 2 h. Amberlyst strong cation exchange resin
[IR120 (H+)] was added and stirring was continued for an additional 5 min. The reaction
mixture was filtered, the solvent removed and the residue dried further under high vacuum to
give 5 a yellow solid: 82.0 mg, quant.; IR (neat); v 3526 (OH), 3262 (NH), 1700 and 1161 cm-1
(ester); 1H NMR (CD3OD; 500 MHz): δ 4.32 (d, 1H, J1,2 9.9 Hz, H-1), 3.85 (dd, 1H, 2J6a,6b 12.1,
J6a,5 2.1 Hz, H-6a), 3.67 (dd, 1H, 2J6b,6a 12.1, J6b,5 5.4 Hz, H-6a), 3.30-3.23 (m, 3H, H-3, H-4,
H-5), 2.81-2.69 (m, 2H, J 9.9 Hz, S-CH2-CH3), 2.61 (t, 1H, J2,1 9.9, J2,3 9.0 Hz, H-2), 1.29 (t, 3H,
J 7.5 Hz, S-CH2-CH3); 13C NMR (CD3OD; 100 MHz): δ 160.2, 159.8 (NHCOCF3), 119.7, 116.8
(NHCOCF3), 87.5 (C-1), 82.2 (C-5), 79.4 (C-3), 71.8 (C-4), 63.0 (C-6), 57.7 (C-2), 25.1 (S-CH2-
CH3), 15.5 (S-CH2-CH3); HRMS: Calcd for C10H16F3NNaO5S+ [M+Na]+ m/z = 342.0593.
Found: 342.0607.
11

3.5 Ethyl 2-trifluoroacetamido-3,4,6-tri-O-benzoyl-1-thio-2-deoxy-β-D-glucopyranoside (6)
A solution of compound 5 (0.63g, 1.98 mmol), BzCl (1.04 mL, 3.00 mmol), DMAP
(12.2 mg, 0.100 mmol), anhydrous pyridine (20 mL) and anhydrous CH2Cl2 (10 mL) was stirred
under nitrogen at room temperature for 2 d. The reaction mixture was diluted with EtOAc (400
mL) and washed with water (100 mL) followed by satd NaHCO3 (100 mL). The organic layer
was dried over anhydrous MgSO4, filtered, and the solvent removed under reduced pressure.
The residue was purified by column chromatography over silica gel using a Et2O:light petroleum
mixture (40%) as the eluent. The main fraction was collected and the solvent removed to give 6
as a white solid: 1.17 g, 92%; mp 176-177 °C; [α]D23-42.2° (c 0.36, CH2Cl2); Rf 0.31 (50%
Et2O/pet. spirit); λabs (CH2Cl2)/nm : 233 (log ε/M-1cm-1, 4.27), 275 (3.24), 284 (3.10); IR (neat);
v 3255 (NH), 1734 and 1267 (ester), 706 cm-1 (Ar); 1H NMR (CDCl3; 500 MHz): δ 8.00-7.98
(AA’BB’C, 2H, Ar-H), 7.92-7.90 (AA’BB’C, 2H, Ar-H), 7.86-7.84 (AA’BB’C, 2H, Ar-H),
7.55-7.50 (AA’BB’C, 2H, Ar-H), 7.45-7.41 (AA’BB’C, 1H, Ar-H), 7.39-7.34 (AA’BB’C, 4H,
Ar-H), 7.29-7.26 (AA’BB’C, 2H, Ar-H), 7.20 (d, 1H, JNH,2 9.5 Hz, NHCOCF3), 5.87 (t, 1H, J3,2
10.2, J3,4 9.7 Hz, H-3), 5.68 (t, 1H, J4,5 9.8 Hz, J4,3 9.7 Hz, H-4), 4.90 (d, 1H, J1,2 10.3 Hz, H-1),
4.64 (dd, 1H, 2J6a,6b 12.3 J6a,5 3.0 Hz, H-6a), 4.52-4.46 (m, 2H, H-2, H-6b), 4.25 (ddd, 1H, J5,4
9.9, J5,6b 5.3, J5,6a 3.0 Hz, H-5), 2.76-2.65 (m, 2H, S-CH2-CH3), 1.21 (t, 3H, J 7.5, J 7.4 Hz,
S-CH2-CH3); 13C NMR (CDCl3; 125 MHz): δ 167.3 (OCOAr), 166.1 (OCOAr), 165.1
(OCOAr), 157.6, 157.3 (NHCOCF3), 134.0 (Ar-CH), 133.6 (Ar-CH), 133.2 (Ar-CH), 129.9
(Ar-CH), 129.7 (Ar-CH), 129.6 (Ar-CH), 129.4 (Ar-C-), 128.60 (Ar-C-), 128.57 (Ar-CH), 128.4
(Ar-CH), 128.3 (Ar-CH), 128.0 (Ar-C-), 116.6, 114.3 (NHCOCF3), 83.8 (C-1), 76.2 (C-5), 73.9
(C-3), 69.4 (C-4), 63.3 (C-6), 53.9 (C-2), 24.3 (S-CH2-CH3), 14.8 (S-CH2-CH3); Anal. Calcd for
C31H28F3NO8S: C, 58.95; H, 4.47; N, 2.22; S, 5.08. Found: C, 58.83; H, 4.43; N, 2.21; S, 4.93.
12

3.6 Ethyl 2-trifluoroacetamido-6-O-tert-butyldiphenylsilyl-3,4-di-O-benzoyl-1-thio-2-deoxy-
β-D-glucopyranoside (7)
A solution of compound 5 (3.49 g, 11.2 mmol), TBDPSCl (5.82 mL, 22.4 mmol), DMAP
(68.4 mg, 0.560 mmol), and anhydrous pyridine (100 mL) was stirred under nitrogen at room
temperature for 2 d. The reaction mixture was cooled in an ice-water bath and then BzCl
(7.80 mL, 67.2 mmol) in anhydrous CH2Cl2 (100 mL) was added to the stirred solution. The
reaction mixture was allowed to warm to room temperature before being stirred at room
temperature for 24 h. The reaction mixture was diluted with EtOAc (400 mL) and washed with
water (100 mL) followed by satd NaHCO3 (100 mL). The organic layer was dried over
anhydrous MgSO4, filtered and the solvent removed. The residue was purified by column
chromatography over silica gel using a Et2O:light petroleum mixture (30%) that included 0.25%
Et3N as the eluent. The main fraction was collected and the solvent removed to give 7 as a white
solid: 7.47 g, 87%; mp 77-79 °C; [α]D23-63.8° (c 0.41, CH2Cl2); Rf 0.62 (50% Et2O/pet. spirit);
λabs (CH2Cl2)/nm : 230 (log ε/M-1cm-1, 4.50), 266 (3.42), 272 (3.42), 283 (3.23); IR (neat); v
3307 (NH), 1723 and 1266 (ester), 1068 and 693 (C-O, C-F), 1027 (Si-O), 702 cm-1 (Ar); 1H
NMR (CDCl3; 500 MHz): δ 7.94-7.92 (AA’BB’C, 2H, Ar-H), 7.84-7.82 (AA’BB’C, 2H, Ar-H),
7.74-7.72 (AA’BB’C, 2H, Ar-H), 7.59-7.57 (AA’BB’C, 2H, Ar-H), 7.54-7.51 (AA’BB’C, 1H,
Ar-H), 7.48-7.44 (AA’BB’C, 1H, Ar-H), 7.42-7.27 (AA’BB’C, 8H, Ar-H), 7.22 (d, 1H, JNH,2
9.5 Hz, NHCOCF3), 7.19-7.16 (AA’BB’C, 2H, Ar-H), 5.82 (t, 1H, J3,4 10.0, J3,2 10.0 Hz, H-3),
5.74 (t, 1H, J4,3 9.5, J4,5 9.5 Hz, H-4), 4.80 (d, 1H, J1,2 10.0 Hz, H-1), 4.49 (q, 1H, J2,1 10.0, J2,3
10.0, J2,NH 9.5 Hz, H-2), 3.93 (dq, 1H, J5,4 9.5, J5,6a 3.5, J5,6b 2.0 Hz, H-5), 3.89-3.83 (m, 2H,
H-6), 2.83-2.71 (m, 2H, S-CH2-CH3), 1.25 (t, 3H, S-CH2-CH3), 1.05 (s, 9H, C(CH3)3); 13C NMR
(CDCl3; 100 MHz): δ 167.5 (OCOAr), 164.8 (OCOAr), 157.6, 157.2 (NHCOCF3), 135.6
13

(Ar-CH), 135.5 (Ar-CH), 133.9 (Ar-CH), 133.4 (Ar-CH), 132.9 (Ar-CH), 132.8 (Ar-C-), 129.9
(Ar-CH), 129.7 (Ar-CH), 129.6 (Ar-CH), 129.5 (Ar-CH), 129.1 (Ar-C-), 128.5 (Ar-CH), 128.4
(Ar-CH), 128.1 (Ar-C-), 127.63 (Ar-CH, Ar-C-), 127.57 (Ar-CH), 116.9, 114.1 (NHCOCF3),
83.4 (C-1), 79.1 (C-5), 74.5 (C-3), 68.8 (C-4), 62.5 (C-6), 53.8 (C-2), 26.5 (C(CH3)3), 23.7 (S-
CH2-CH3), 19.1 (C(CH3)3), 14.9 (S-CH2-CH3); Anal. Calcd for C40H42F3NO7SSi: C, 62.73; H,
5.53; N, 1.83; S, 4.19. Found: C, 62.71; H, 5.57; N, 1.81; S, 3.78.
3.7 6-O-(2-Trifluoroacetamido-3,4,6-tri-O-benzoyl-2-deoxy-β-D-glucopyranosyl)-2-
acetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl azide (8)
A solution of glycosyl acceptor 3 (23.6 mg, 51.9 µmol), glycosyl donor 6 (32.8 mg, 51.9 µmol),
NIS (17.5 mg, 77.9 µmol) and anhydrous CH2Cl2 (5 mL) was stirred under nitrogen at room
temperature for 30 min. TMSOTf (0.9 µL, 4.97 µmol) was added to the reaction mixture and
stirring was continued for 24 h. Et3N (4.0 µL) was added to quench the reaction and the solvent
was removed. The residue was purified by column chromatography over silica gel using a
Et2O:light petroleum mixture (90%) as the eluent. The main fraction was collected and the
solvent removed to give 8 as a white solid: 29.7 mg, 86%; mp 141-143 °C (dec.); [α]D24-36.1° (c
0.38, CH2Cl2); Rf 0.61 (100% Et2O); λabs (CH2Cl2)/nm : 233 (log ε/M-1cm-1, 5.33), 275 (4.24),
283 (4.16); IR (neat); v 3337 (NH), 2117 (N3), 1722 and 1264 (ester), 1067 and 690 (C-O, C-F),
706 cm-1 (Ar); 1H NMR (CDCl3; 500 MHz): δ 7.95-7.90 (AA’BB’C, 6H, Ar-H), 7.85-7.82
II
(AA’BB’C, 4H, Ar-H), 7.73 (d, 1H, JNH,2 9.0 Hz, NHCOCF3 ), 7.50-7.42 (AA’BB’C, 4H,
Ar-H), 7.40-7.26 (AA’BB’C, 9H, Ar-H), 7.25-7.20 (AA’BB’C, 2H, Ar-H), 6.10 (d, 1H, JNH,2
I
8.6 Hz, NHCOCH3 ), 5.93 (t, 1H, J3,2 10.4, J3,4 9.6 Hz, H-3I), 5.76-5.71 (m, 2H, H-3II, H-4II),
5.46 (t, 1H, J4,5 9.7, J4,3 9.7 Hz, H-4I), 5.11 (d, 1H, J1,2 9.2 Hz, H-1I), 4.81 (d, 1H, J1,2 8.4 Hz,
H-1II), 4.61 (q, 1H, J2,3 10.1, J2,1 8.7, J2,NH 8.7 Hz, H-2II), 4.56 (dd, 1H, J6a,6b 12.3, J6a,5 3.1 Hz,
14

II
H-6aII), 4.42 (dd, 1H, 2J6b,6a 12.3, J6b,5 4.9 Hz, H-6b ), 4.24 (dd, 1H, J6a,6b 11.8, J6a,5 1.5 Hz,
H-6aI), 4.10-4.07 (br m, 1H, H-5II), 4.01 (dq, 1H, J5,4 10.0, J5,6b 5.0, J5,6a 1.7 Hz, H-5I), 3.97 (q,
I
1H, J2,3 10.3, J2,1 9.4, J2,NH 9.1 Hz, H-2I), 3.63 (dd, 1H, 2J6b,6a 11.9, J6b,5 5.2 Hz, H-6b ), 1.82 (s,
I
I
3H, NHCOCH3 ); 13C NMR (CDCl3; 125 MHz): δ 170.8 (NHCOCH3 ) 166.5 (OCOAr), 166.3
II
(OCOAr), 166.1 (OCOAr), 165.7 (OCOAr), 165.0 (OCOAr), 157.9, 157.6 (NHCOCF3 ), 133.8
(Ar-CH), 133.6 (Ar-CH), 133.5 (Ar-CH), 133.4 (Ar-CH), 133.1 (Ar-CH), 129.85 (Ar-CH),
129.83 (Ar-CH), 129.80 (Ar-CH), 129.7 (Ar-CH), 129.6 (Ar-CH), 129.3 (Ar-C-), 128.7 (Ar-C-),
128.51 (Ar-C-), 128.48 (Ar-CH), 128.44 (Ar-C-), 128.42 (Ar-CH), 128.40 (Ar-CH), 128.34
II
(Ar-CH), 128.27 (Ar-CH), 128.1 (Ar-C-), 116.9, 114.6 (NHCOCF3 ), 101.6 (C-1II), 88.3 (C-1I),
75.4 (C-5I), 72.8 (C-3II), 72.3 (C-5II), 72.1 (C-3I), 69.2 (C-4II), 69.1 (C-4I), 68.4 (C-6I), 62.8
I
(C-6II), 54.9 (C-2I), 54.8 (C-2II), 23.1 (NHCOCH3 ); Anal. Calcd for C51H44F3N5O15Si: C, 59.82;
H, 4.33; N, 6.84. Found: C, 59.85; H, 4.42; N, 6.75.
3.8 6-O-(2-Trifluoroacetamido-6-O-tert-butyldiphenylsilyl-3,4-di-O-benzoyl-2-deoxy-β-D-
glucopyranosyl)-2-acetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl azide (9)
A solution of glycosyl acceptor 3 (1.16 g, 2.56 mmol), glycosyl donor 7 (2.35 g, 3.07 mmol),
NIS (0.83 g, 0.31 mmol) and anhydrous CH2Cl2 (20 mL) was stirred under nitrogen at room
temperature for 30 min. TMSOTf (46.2 µL, 0.260 mmol) was added to the reaction mixture and
stirring was continued for 25 h. Et3N (17.0 µL) was added to quench the reaction and the solvent
was removed. The residue was purified by column chromatography over silica gel using an
Et2O:light petroleum mixture (50%) that included 0.25% Et3N as the eluent. The main fraction
was collected and the solvent removed to give 9 as a white solid: 2.46 g, 83%; mp 94-96 °C;
[α]D24-44.1° (c 0.24, CH2Cl2); Rf 0.77 (100% Et2O); λabs (CH2Cl2)/nm : 232 (log ε/M-1cm-1,
4.80), 272 (3.95), 283 (3.86); IR (neat); v 3332 (NH), 2118 (N3), 1724 and 1268 (ester), 1068
15

and 690 (C-O, C-F), 1025 (Si-O), 705 cm-1 (Ar); 1H NMR (CDCl3; 500 MHz): δ 7.97-7.92
(AA’BB’C, 4H, Ar-H), 7.90-7.84 (AA’BB’C, 4H, Ar-H), 7.66-7.64 (AA’BB’C, 2H, Ar-H),
II
7.57-7.49 (AA’BB’C, 6H, Ar-H), 7.42-7.34 (m, 10H, NHCOCF3 , Ar-H), 7.30-7.25 (AA’BB’C,
3H, Ar-H), 7.18-7.15 (AA’BB’C, 2H, Ar-H), 5.85 (t, 1H, J3,4 9.5, J3,2 9.4 Hz, H-3I), 5.68 (d, 1H,
I
JNH,2 8.3 Hz, NHCOCH3 ), 5.62 (t, 1H, J4,3 9.6, J4,5 9.6 Hz, H-4II), 5.55 (t, 1H, J3,2 10.4, J3,4
9.6 Hz, H-3II), 5.48 (t, 1H, J4,5 9.7, J4,3 9.6 Hz, H-4I), 5.12 (d, 1H, J1,2 9.2 Hz, H-1I), 4.60 (d, 1H,
J1,2 8.4 Hz, H-1II), 4.41 (q, 1H, J2,3 10.4, J2,NH 8.7, J2,1 8.7 Hz, H-2II), 4.20 (dd, 1H, 2J6a,6b 12.0,
J6a,5 1.9 Hz, H-6aI), 3.94 (dq, 1H, J5,4 10.0, J5 6b 4.5, J5,6a 1.9 Hz, H-5I), 3.85 (q, 1H, J2,3 10.7, J2,1
8.9, J2,NH 8.6 Hz, H-2I), 3.82-3.77 (m, 2H, H-6II), 3.72 (dq, 1H, J5,4 9.6, J5,6b 4.6, J5,6a 2.4 Hz,
I
I
H-5II), 3.49 (dd, 1H, 2J6b,6a 12.1, J6b,5 4.6 Hz, H-6b ), 1.92 (s, 3H, NHCOCH3 ), 0.99 (s, 9H,
I
C(CH3)3); 13C NMR (CDCl3; 100 MHz): δ 170.9 (NHCOCH3 ), 166.8 (OCOAr), 166.4
I
(OCOAr), 165.7 (OCOAr), 164.9 (OCOAr), 157.7, 157.3 (NHCOCF3 ), 135.6 (Ar-CH), 135.4
(Ar-CH), 133.9 (Ar-CH), 133.6 (Ar-CH), 133.5 (Ar-CH), 133.3 (Ar-CH), 133.0 (Ar-CH), 132.8
(Ar-CH), 129.9 (Ar-CH), 129.74 (Ar-CH), 129.65 (Ar-CH), 129.55 (Ar-CH), 129.0 (Ar-C-),
128.53 (Ar-CH, Ar-C-), 128.48 (Ar-CH, Ar-C-), 128.45 (Ar-CH), 128.40 (Ar-CH), 128.32
II
(Ar-CH), 128.24 (Ar-C-), 127.56 (Ar-CH), 127.53 (Ar-CH), 117.2, 114.3 (NHCOCF3 ), 101.5
(C-1II), 88.2 (C-1I), 75.4 (C-5II), 75.3 (C-5I), 73.3 (C-3II), 72.2 (C-3I), 69.1 (C-4I), 68.8 (C-4II),
I
67.9 (C-6I), 62.6 (C-6II), 55.0 (C-2I), 54.9 (C-2II), 26.6 (C(CH3)3), 23.1 (NHCOCH3 ), 19.1
(C(CH3)3); HRMS: Calcd for C60H58F3N5NaO14Si+ [M+Na]+ m/z = 1180.3594. Found:
1180.3551.
3.9 6-O-(2-Trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl)-2-acetamido-
3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl azide (10)
16

A solution of disaccharide 9 (0.43 g, 0.37 mmol) in anhydrous THF (5 mL), HOAc
(0.430 mL, 7.45 mmol) and TBAF (3.60 mL, 3.60 mmol) was stirred at room temperature for 19
h. The reaction mixture was diluted with Et2O (300 mL) and washed with satd NH4Cl solution
(50 mL). The organic layer was dried over anhydrous MgSO4, filtered and the solvent removed.
The residue was purified by column chromatography over silica gel using Et2O (100%) as the
eluent. The main fraction was collected and the solvent removed to give 10 as a white solid:
0.34 g, quant.; mp 136-138 °C; [α]D24+1.2° (c 0.59, CH2Cl2); Rf 0.19 (100% Et2O); λabs
(CH2Cl2)/nm : 234 (log ε/M-1cm-1, 4.70), 276 (3.68), 283 (3.61), 324 (3.22); IR (neat); v 3336
(NH), 2117 (N3), 1721 and 1261 (ester), 1068 and 690 (C-O, C-F), 707 cm-1 (Ar); 1H NMR
II
(CDCl3; 500 MHz): δ 7.95-7.88 (AA’BB’C, 8H, Ar-H), 7.56-7.46 (m, 5H, NHCOCF3 , Ar-H),
I
7.40-7.33 (AA’BB’C, 8H, Ar-H), 5.92 (d, 1H, JNH,2 8.5 Hz, NHCOCH3 ), 5.84 (t, 1H, J3,2 9.5,
J3,4 9.5 Hz, H-3I), 5.70 (t, 1H, J3,2 9.7, J3,4 9.6 Hz, H-3II), 5.51 (t, 1H, J4,5 9.7, J4,3 9.6 Hz, H-4I),
5.41 (t, 1H, J4,5 9.6, J4,3 9.6 Hz, H-4II), 5.08 (d, 1H, J1,2 9.2 Hz, H-1I), 4.75 (d, 1H, J1,2 8.4 Hz,
H-1II), 4.36 (q, 1H, J2,NH 10.8, J2,3 8.7, J2,1 8.6 Hz, H-2II), 4.25 (dd, 1H, 2J6a,6b 11.5, J6a,5 2.3 Hz,
II
H-6aI), 4.02-3.92 (m, 2H, H-2I, H-5I), 3.78 (dd, 1H, 2J6a,6b 12.6, J6a,5 1.8 Hz, H-6a ), 3.72-3.62
I
II
I
(m, 3H, H-5II, H-6b , H-6b ), 1.89 (s, 3H, NHCOCH3 ); 13C NMR (CDCl3; 100 MHz): δ 170.7
(NHCOCH3), 166.6 (OCOAr), 166.4 (OCOAr), 166.0 (OCOAr), 165.8 (OCOAr), 157.7, 157.3
(NHCOCF3), 134.0 (Ar-CH), 133.73 (Ar-CH), 133.69 (Ar-CH), 133.62 (Ar-CH), 130.0
(Ar-CH), 129.89 (Ar-CH), 129.86 (Ar-CH), 129.79 (Ar-CH), 128.7 (Ar-CH), 128.51 (Ar-CH,
Ar-C-), 128.48 (Ar-CH, Ar-C-), 128.44 (Ar-CH), 128.3 (Ar-C-), 117.1, 114.3 (NHCOCF3),
101.2 (C-1II), 88.3 (C-1I), 75.1 (C-5I), 74.8 (C-5II), 72.6 (C-3II), 72.0 (C-3I), 69.2 (C-4I), 69.0
(C-4II), 67.9 (C-6I), 61.1 (C-6II), 55.0 (C-2I), 54.7 (C-2II), 23.3 (NHCOCH3); HRMS: Calcd for
C44H40F3N5NaO14+ [M + Na]+ m/z = 942.2416. Found: 942.2386.
17

3.10 6-O-[6-O-(2-Trifluoroacetamido-3,4,6-tri-O-benzoyl-2-deoxy-β-D-glucopyranosyl)-2-
trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl]-2-acetamido-3,4-di-O-
benzoyl-2-deoxy-β-D-glucopyranosyl azide (11)
A solution of glycosyl acceptor 10 (0.63 g, 0.68 mmol), glycosyl donor 6 (0.48 g, 0.75 mmol),
NIS (0.250 g, 1.13 mmol) and anhydrous CH2Cl2 (10 mL) was stirred under nitrogen at room
temperature for 30 min. TMSOTf (12.4 µL, 0.068 mmol) was added to the reaction mixture and
stirring was continued for 19 h. Et3N (70.0 µL) was added to quench the reaction and the solvent
was removed. The residue was purified by column chromatography over silica gel using an
Et2O:light petroleum mixture (80%) as the eluent. The main fraction was collected and the
solvent removed to give 11 as a white solid: 0.76 g, 95%; mp 150-152 °C (dec.); [α]D24+39.7° (c
0.46, CH2Cl2); Rf 0.31 (80% Et2O/pet. spirit); λabs (CH2Cl2)/nm : 234 (log ε/M-1cm-1, 4.93), 275
(3.88), 284 (3.78); IR (neat); v 3323 (NH), 2118 (N3), 1720 and 1268 (ester), 1065 and 690 (C-O,
II
C-F), 707 cm-1 (Ar); 1H NMR (CDCl3; 500 MHz): δ 7.94-7.83 (m, 15H, NHCOCF3 , Ar-H),
II
7.52-7.43 (AA’BB’C, 7H, Ar-H), 7.36-7.26 (m, 15H, NHCOCF3 , Ar-H), 6.09 (d, 1H, JNH,2 8.7,
I
NHCOCH3 ), 5.88 (t, 1H, J3,2 10.3, J3,4 9.8 Hz, H-3I), 5.78 (t, 1H, J3,4 10.4, J3,2 9.5 Hz, H-3III),
5.73-5.69 (m, 2H, H-3II, H-4III), 5.46 (t, 1H, J4,3 9.7, J4,5 9.7 Hz, H-4I), 5.38 (t, 1H, J4,5 9.7, J4,3
9.6 Hz, H-4II), 5.08 (d, 1H, J1,2 9.2 Hz, H-1I), 4.80 (d, 1H, J1,2 8.3 Hz, H-1III), 4.74 (d, 1H, J1,2
8.4 Hz, H-1II), 4.56-4.51 (m, 2H, H-2III, H-6a ), 4.42 (dd, 1H, 2J6b,6a 12.3, J6b,5 5.3 Hz, H-6aIII),
III
I
II
4.26 (q, 1H, J2,3 10.6, J2,NH 8.9, J2,1 8.6 Hz, H-2II), 4.14-4.04 (m, 4H, H-5I, H-5III, H-6a , H-6a ),
4.02 (q, 1H, J2,3 10.3, J2,1 9.2, J2,NH 9.1 Hz, H-2I), 3.89 (ddd, 1H, J5,4 9.9, J5,6b 5.8, J5,6a 1.7 Hz,
I
H-5II), 3.72 (dd, 1H, 2J6b,6a 12.2, J6b,5 5.4 Hz, H-6b ), 3.65 (dd, 1H, 2J6b,6a 11.9, J6b,5 5.8 Hz,
II
I
H-6b ), 1.84 (s, 3H, NHCOCH3 ); 13C NMR (CDCl3; 125 MHz): δ 170.9 (NHCOCH3), 166.6
(OCOAr), 166.4 (OCOAr), 166.3 (OCOAr), 166.1 (OCOAr), 166.0 (OCOAr), 165.6 (OCOAr),
18

II
III
165.1 (OCOAr), 157.88, 157.64, 157.59, 157.34, (NHCOCF3 , NHCOCF3 ), 133.85 (Ar-CH),
133.77 (Ar-CH), 133.57 (Ar-CH), 133.55 (Ar-CH), 133.53 (Ar-CH), 133.46 (Ar-CH), 133.21
(Ar-CH), 129.91 (Ar-CH), 129.85 (Ar-CH), 129.81 (Ar-CH), 129.73 (Ar-CH), 129.67 (Ar-CH),
129.3 (Ar-C-), 128.68 (Ar-C-), 128.56 (Ar-CH, Ar-C-), 128.49 (Ar-CH, Ar-C-), 128.47 (Ar-CH),
128.42 (Ar-CH, Ar-C-), 128.37 (Ar-CH), 128.2 (Ar-C-), 116.84, 116.78, 114.55, 114.49,
II
III
(NHCOCF3 , NHCOCF3 ), 101.6 (C-1III), 101.2 (C-1II), 88.3 (C-1I), 75.2 (C-5I), 73.5 (C-5II),
72.7 (C-3III), 72.42 (C-3II), 72.37 (C-5III), 72.2 (C-3I), 69.6 (C-4I), 69.4 (C-4III), 69.3 (C-4II), 69.0
(C-6II), 68.8 (C-6I), 63.0 (C-6III), 55.0 (C-2II, C-2III), 54.8 (C-2I), 23.1 (NHCOCH3); Anal. Calcd
for C73H62F6N6O22: C, 58.87; H, 4.20; N, 5.64. Found: C, 58.66; H, 4.32; N, 5.46.
3.11 6-O-[6-O-(2-Trifluoroacetamido-6-O-tert-butyldiphenylsilyl 3,4-di-O-benzoyl-2-deoxy-
β-D-glucopyranosyl)-2-trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl]-
2-acetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl azide (12)
A solution of glycosyl acceptor 10 (1.02 g, 1.11 mmol), glycosyl donor 7 (1.02 g, 1.33 mmol),
NIS (0.45 g, 2.0 mmol) and anhydrous CH2Cl2 (15 mL) was stirred under nitrogen at room
temperature for 30 min. TMSOTf (20.0 µL, 0.11 mmol) was added to the reaction mixture and
stirring was continued for 19 h. Et3N (0.11 mL) was added to quench the reaction and the
solvent was removed. The residue was purified by column chromatography over silica gel using
an Et2O:light petroleum mixture (75%) that included 0.25% Et3N as the eluent. The main
fraction was collected and the solvent removed to give 12 as a white solid: 1.16 g, 65%; mp 138-
140 °C (dec.); [α]D24+26.7° (c 0.49, CH2Cl2); Rf 0.89 (100% Et2O); λabs (CH2Cl2)/nm : 234 (log
ε/M-1cm-1, 4.87), 274 (3.85), 283 (3.76); IR (neat); v 3330 (NH), 2118 (N3), 1724 and 1270
(ester), 1067 and 690 (C-O, C-F), 1025 (Si-O), 706 cm-1 (Ar); 1H NMR (CDCl3; 500 MHz): δ
7.95-7.87 (AA’BB’C, 10H, Ar-H), 7.84-7.82 (AA’BB’C, 2H, Ar-H), 7.59-5.57 (AA’BB’C, 2H,
19

III
Ar-H), 7.55-7.46 (m, 9H, NHCOCF3 , Ar-H), 7.39-7.31 (AA’BB’C, 12H, Ar-H), 7.29 (d, 1H,
II
JNH,2 9.0 Hz, NHCOCF3 ), 7.26-7.18 (AA’BB’C, 4H, Ar-H), 7.14-7.11 (AA’BB’C, 2H, Ar-H),
I
5.90-5.84 (m, 2H, NHCOCH3 , H-3I), 5.69 (t, 1H, J3,2 9.5, J3,4 9.5 Hz, H-3II), 5.64-5.58 (m, 2H,
H-3III, H-4III), 5.48 (t, 1H, J4,5 10.0, J4,3 9.5 Hz, H-4I), 5.43 (t, 1H, J4,5 9.5, J4,3 9.5 Hz, H-4II),
5.10 (d, 1H, J1,2 9.0 Hz, H-1I), 4.72 (d, 1H, J1,2 8.0 Hz, H-1II), 4.64 (d, 1H, J1,2 8.5 Hz, H-1III),
4.40 (q, 1H, J2,3 9.5, J2,NH 9.0, J2,1 9.0 Hz, H-2III), 4.28 (q, 1H, J2,3 11.0, J2,NH 8.5, J2,1 8.5 Hz,
I
II
H-2II), 4.21 (dd, 1H, J6b,6a 11.5, J6b,5 1.5 Hz, H-6b ), 4.12 (dd, 1H, J6b,6a 11.5, J6b,5 1.5 Hz, H-6b ),
4.04 (ddd, 1H, J5,4 10.0, J5,6a 4.5, J5,6b 2.0 Hz, H-5I), 3.95 (q, 1H, J2,NH 9.5, J2,1 9.0, J2,3 9.0 Hz,
H-2I), 3.88 (ddd, 1H, J5,4 10.0, J5,6a 5.5, J5,6b 1.5 Hz, H-5II), 3.80-3.77 (m, 1H, H-6III), 3.75-3.70
(m, 1H, H-5III), 3.66 (dd, 1H, 2J6a,6b 12.0, J6a,5 4.5 Hz, H-6aI), 3.54 (dd, 1H, 2J6a,6b 11.5, J6a,5
I
5.5 Hz, H-6aII), 1.88 (s, 3H, NHCOCH3 ), 0.95 (s, 9H, C(CH3)3); 13C NMR (CDCl3; 100 MHz): δ
I
170.8 (NHCOCH3 ), 166.8 (OCOAr), 166.4 (2 x OCOAr), 166.0 (OCOAr), 165.7 (OCOAr),
II
III
164.9 (OCOAr), 157.7, 157.6, 157.30, 157.26 (NHCOCF3 , NHCOCF3 ), 135.5 (Ar-CH), 135.4
(Ar-CH), 133.92 (Ar-CH), 133.89 (Ar-CH), 133.60 (Ar-CH), 133.56 (Ar-CH), 133.51 (Ar-CH),
133.3 (Ar-CH), 132.9 (Ar-CH), 132.8 (Ar-CH), 130.0 (Ar-CH), 129.81 (Ar-C-), 129.79
(Ar-CH), 129.68 (Ar-CH, Ar-C-), 129.63 (Ar-CH), 129.57 (Ar-CH), 129.0 (Ar-CH), 128.6
(Ar-CH, Ar-C-), 128.53 (Ar-CH), 128.48 (Ar-CH), 128.4 (Ar-CH, Ar-C-), 128.36 (Ar-CH),
128.34 (Ar-CH), 128.30 (Ar-C-), 128.26 (Ar-C-), 127.5 (Ar-CH), 117.2, 117.1, 114.30, 114.26
II
III
(NHCOCF3 , NHCOCF3 ), 101.5 (C-1III), 101.2 (C-1II), 88.3 (C-1I), 75.33 (C-5III), 75.25 (C-5I),
73.5 (C-5II), 73.2 (C-3III), 72.6 (C-3II), 72.1 (C-3I), 69.3 (C-4I), 69.2 (C-4II), 68.8 (C-4III), 68.3
(C-6I, C-6II), 62.7 (C-6III), 55.0 (C-2III), 54.94 (C-2I), 54.87 (C-2II), 26.5 (C(CH3)3), 23.2
I
(NHCOCH3 ), 19.1 (C(CH3)3); Anal. Calcd for C82H76F6N6O21Si: C, 60.66; H, 4.72; N, 5.18.
Found: C, 60.96; H, 5.14; N, 4.89.
20

3.12 6-O-[6-O-(2-Trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl)-2-
trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl]-2-acetamido-3,4-di-O-
benzoyl-2-deoxy-β-D-glucopyranosyl azide (13)
A solution of trisaccharide 12 (93.2 mg, 0.060 mmol) in anhydrous THF (3 mL), HOAc
(65.7 µL, 1.15 mmol) and TBAF (0.57 mL, 0.57 mmol) was stirred at room temperature for 24 h.
The reaction mixture was diluted with Et2O (200 mL) and washed with satd NH4Cl solution (50
mL). The organic layer was dried over anhydrous MgSO4, filtered and the solvent removed.
The residue was purified by column chromatography over silica gel using an Et2O:light
petroleum mixture (90%) as the eluent. The main fraction was collected and the solvent
removed to give 13 as a white solid: 79.5 mg, quant.; mp 151-153 °C (dec.); [α]D23-5.7° (c 0.69,
CH2Cl2); Rf 0.42 (100% Et2O); λabs (CH2Cl2)/nm : 234 (log ε/M-1cm-1, 4.97), 276 (3.91), 284
(3.81); IR (neat); v 3336 (NH), 2118 (N3), 1724 and 1272 (ester), 1068 and 690 (C-O, C-F), 708
cm-1 (Ar); 1H NMR (CDCl3; 500 MHz): δ 7.94-7.88 (AA’BB’C, 12H, Ar-H), 7.84 (br d, 1H,
III
NHCOCF3 ), 7.54-7.46 (AA’BB’C, 7H, Ar-H), 7.38-7.30 (m, 12H, NHCOCF3 , Ar-H), 6.31
II
I
(br d, 1H, NHCOCH3 ), 5.86-5.82 (m, 2H, H-3I, H-3II), 5.77 (t, 1H, J3,4 9.5, J3,2 9.5 Hz, H-3III),
5.49 (br t, 2H, H-4I, H-4II), 5.34 (t, 1H, J4,5 9.7, J4,3 9.6 Hz, H-4III), 5.07 (d, 1H, J1,2 9.1 Hz, H-1I),
4.87 (d, 1H, J1,2 8.3 Hz, H-1II), 4.75 (d, 1H, J1,2 8.3 Hz, H-1III), 4.33 (q, 1H, J2,3 10.5, J2,NH 8.7,
II
J2,1 8.6 Hz, H-2III), 4.22-4.05 (m, 5H, H-2I, H-2II, H-5I, H-6aI, H-6a ), 3.89-3.86 (br m, 1H, H-5II),
I
3.79 (br d, 1H, J6a,6b 12.5 Hz, H-6aIII), 3.75-3.68 (m, 2H, H-5III, H-6b ), 3.65 (dd, 1H, 2J6b,6a 11.5,
II
III
I
J6b,5 3.5 Hz, H-6b ), 3.60 (dd, 1H, 2J6b,6a 12.5, J6b,5 4.5 Hz, H-6b ), 1.86 (s, 3H, NHCOCH3 ); 13C
I
NMR (CDCl3; 125 MHz): δ 171.1 (NHCOCH3 ), 166.52 (OCOAr), 166.45 (OCOAr), 166.3
II
(OCOAr), 166.0 (2 x OCOAr), 165.8 (OCOAr), 157.9, 157.7, 157.6, 157.4 (NHCOCF3 ,
III
NHCOCF3 ), 133.9 (Ar-CH), 133.8 (Ar-CH), 133.7 (Ar-CH), 133.6 (Ar-CH), 133.5 (Ar-CH),
21

129.94 (Ar-CH), 129.86 (Ar-CH, Ar-C-), 129.83 (Ar-CH), 129.79 (Ar-CH), 128.6 (Ar-CH),
128.5 (Ar-CH, Ar-C-), 128.42 (Ar-CH), 128.37 (Ar-C-), 116.82, 116.78, 114.53, 114.49
II
III
(NHCOCF3 , NHCOCF3 ), 101.09 (C-1III), 101.02 (C-1II), 88.3 (C-1I), 75.4 (C-5I), 74.8 (C-5III),
73.0 (C-5II), 72.6 (C-3III), 72.4 (C-3I), 72.1 (C-3II), 69.6 (C-4I), 69.4 (C-4II), 69.3 (C-4III), 68.9
I
(C-6I), 68.3 (C-6II), 61.1 (C-6III), 55.4 (C-2II), 54.8 C-2III), 54.7 (C-2I), 23.0 (NHCOCH3 );
HRMS: Calcd for C66H58F6N6NaO21+ [M + Na]+ m/z = 1407.3451. Found: 1407.3448.
3.13 6-O-[6-O-(6-O-[2-Trifluoroacetamido-3,4,6-tri-O-benzoyl-2-deoxy-β-D-
glucopyranosyl]-2-trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl)-2-
trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl]-2-acetamido-3,4-di-O-
benzoyl-2-deoxy-β-D-glucopyranosyl azide (14)
A solution of glycosyl acceptor 13 (0.56 g, 0.40 mmol), glycosyl donor 6 (0.28 g, 0.44 mmol),
NIS (0.15 g, 0.66 mmol) and anhydrous CH2Cl2 (10 mL) was stirred under nitrogen at room
temperature for 30 min. TMSOTf (8.0 µL, 0.04 mmol) was added to the reaction mixture and
stirring was continued for 23 h. Et3N (37.0 µL) was added to quench the reaction and the solvent
was removed. The residue was purified by column chromatography over silica gel using an
Et2O:light petroleum mixture (85%). The main fraction was collected and the solvent removed
to give 14 as a white solid: 0.60 g, 77%; mp 160-162 °C; [α]D24-43.2° (c 1.03, CH2Cl2); Rf 0.34
(100% Et2O); λabs (CH2Cl2)/nm : 233 (log ε/M-1cm-1, 5.09), 275 (4.04), 284 (3.96); IR (neat); v
3329 (NH), 2118 (N3), 1720 and 1269 (ester), 1067 and 690 (C-O, C-F), 708 cm-1 (Ar); 1H NMR
II
(CDCl3; 500 MHz): δ 8.18 (d, 1H, JNH,2 8.5 Hz, NHCOCF3 ), 8.11-8.01 (AA’BB’C, 12H, Ar-H),
IV
7.98 (d, 1H, JNH,2 9.0 Hz, NHCOCF3 ), 7.95-7.94 (AA’BB’C, 2H, Ar-H), 7.91-7.89 (AA’BB’C,
2H, Ar-H), 7.67-7.65 (AA’BB’C, 2H, Ar-H), 7.63-7.60 (AA’BB’C, 1H, Ar-H), 7.56-7.53
(AA’BB’C, 2H, Ar-H), 7.50-7.40 (AA’BB’C, 10H, Ar-H), 7.38-7.36 (AA’BB’C, 2H, Ar-H),
22

7.32-7.28 (AA’BB’C, 8H, Ar-H), 7.25-7.22 (AA’BB’C, 2H, Ar-H), 7.19 (d, 1H, JNH,2 9.5 Hz,
I
III
NHCOCH3 ), 7.10-7.06 (m, 3H, NHCOCF3 , Ar-H), 6.05-5.97 (m, 2H, H-3II, H-4IV), 5.88-5.82
(m, 2H, H-3I, H-3IV), 5.71 (t, 1H, J4,3 9.5, J4,5 9.5 Hz, H-4III), 5.43 (t, 1H, J4,3 9.7, J4,5 9.7 Hz,
H-4I), 5.28-5.21 (m, 2H, H-3III, H-4II), 5.05 (d, 1H, J1,2 9.2 Hz, H-1I), 4.90 (d, 1H, J1,2 8.3 Hz,
H-1II), 4.81 (br dd, 1H, J6a,6b 12.1, J6a,5 4.4 Hz, H-6aIV), 4.76-4.56 (m, 8H, H-1III, H-1IV, H-2I,
H-2II, H-2III, H-2IV, H-5I, H-5II), 4.22 (t, 1H, J6a,6b 11.7 Hz, H-6aII), 4.20-4.11 (m, 4H, H-5III,
IV
II
III
H-5IV, H-6aI, H-6b ), 3.97 (d, 1H, 2J6b,6a 11.6 Hz, H-6b ), 3.90-3.85 (m, 1H, H-6a ), 3.65-3.59
I
III
I
(m, 1H, H-6b ), 3.40 (d, 1H, 2J6b,6a 11.9 Hz, H-6b ), 1.61 (s, 3H, NHCOCH3 ); 13C NMR (CDCl3;
I
100 MHz): δ 171.4 (NHCOCH3 ), 166.6 (OCOAr), 166.5 (OCOAr), 166.42 (OCOAr), 166.36
(OCOAr), 166.2 (OCOAr), 165.6 (OCOAr), 165.2 (OCOAr), 164.9 (OCOAr), 158.6, 158.21,
II
III
IV
158.18, 158.1, 157.83, 157.76 (NHCOCF3 , NHCOCF3 , NHCOCF3 ), 134.1 (Ar-CH), 133.78
(Ar-CH), 133.76 (Ar-CH), 133.73 (Ar-CH), 133.66 (Ar-CH), 133.5 (Ar-CH), 133.3 (Ar-CH),
133.2 (Ar-CH), 130.2 (Ar-CH), 130.14 (Ar-CH, Ar-C-), 130.07 (Ar-CH), 130.06 (Ar-CH), 129.9
(Ar-CH), 129.84 (Ar-CH), 129.77 (Ar-CH), 129.7 (Ar-CH), 129.5 (Ar-C-), 129.3 (Ar-C-), 129.1
(Ar-C-), 128.98 (Ar-C-), 128.89 (Ar-CH), 128.76 (Ar-CH), 128.68 (Ar-C-), 128.64 (Ar-CH),
128.57 (Ar-CH), 128.52 (Ar-CH), 128.45 (Ar-CH), 128.43 (Ar-C-), 128.35 (Ar-CH), 128.32
II III
(Ar-C-), 128.25 (Ar-CH), 117.0, 116.9, 116.6, 114.2, 114.1, 113.7, (NHCOCF3 , NHCOCF3 ,
NHCOCF3 ), 104.0 (C-1IV), 103.1 (C-1III), 101.7 (C-1II), 89.2 (C-1I), 74.6 (C-5I), 73.8 (C-5III,
IV
C-5IV), 73.6 (C-6II), 73.4 (C-5II), 73.2 (C-6III), 72.8 (C-3I), 72.62 (C-3III), 72.55 (C-3II), 71.8
(C-6I), 71.30 (C-3IV), 71.25 (C-4I), 71.1 (C-4II), 69.6 (C-4IV), 69.4 (C-4III), 63.6 (C-6IV), 55.4
I
(C-2III), 55.2 (C-2IV), 54.4 (C-2II), 53.4 (C-2I), 22.6 (NHCOCH3 ); Anal. Calcd for
C95H80F9N7O29: C, 58.37; H, 4.13; N, 5.02. Found: C, 58.08; H, 4.24; N, 4.97.
23

3.14 6-O-[6-O-(6-O-[2-Trifluoroacetamido-6-O-tert-butyldiphenylsilyl-3,4-di-O-benzoyl-2-
deoxy-β-D-glucopyranosyl)]-2-trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-
glucopyranosyl)-2-trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl]-2-
acetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl azide (15)
A solution of glycosyl acceptor 13 (31.3 mg, 0.020 mmol), glycosyl donor 7 (19.0 mg, 0.020
mmol), NIS (8.4 mg, 0.04 mmol) and anhydrous CH2Cl2 (13 mL) was stirred under nitrogen at
room temperature for 30 min. TMSOTf (0.5 µL, 2.76 µmol) was added to the reaction mixture
and stirring was continued for 23 h. Et3N (1.0 µL) was added to quench the reaction and the
solvent was removed. The residue was purified by column chromatography over silica gel using
an Et2O:light petroleum mixture (75%). The main fraction was collected and the solvent
removed to give 15 as a white solid: 33.1 mg, 70%; mp 118 °C (dec.); [α]D24-76.3° (c 0.12,
CH2Cl2); Rf 0.66 (100% Et2O); λabs (CH2Cl2)/nm : 233 (log ε/M-1cm-1, 5.14), 274 (4.11), 284
(4.00); IR (neat); v 3324 (NH), 2116 (N3), 1721 and 1271 (ester), 1067 and 690 (C-O, C-F), 1025
II
(Si-O), 708 cm-1 (Ar); 1H NMR (CDCl3; 500 MHz): δ 8.12-8.08 (m, 3H, NHCOCF3 , Ar-H),
IV
8.03-7.91 (m, 14H, NHCOCF3 , Ar-H), 7.60 (AA’BB’C, 2H, Ar-H), 7.52-7.41 (AA’BB’C, 8H,
Ar-H), 7.40-7.28 (AA’BB’C, 13H, Ar-H), 7.23-7.16 (AA’BB’C, 5H, Ar-H), 7.13-7.10
I
III
(AA’BB’C, 5H, Ar-H), 7.05 (d, 1H, JNH,2 9.1 Hz, NHCOCH3 ), 6.98-6.93 (m, 3H, NHCOCF3 ,
Ar-H), 5.90 (t, 1H, J3,4 10.5, J3,2 10.5 Hz, H-3II), 5.87-5.80 (m, 2H, H-3I, H-4IV), 5.77 (t, 1H, J3,4
10.0, J3,2 9.5 Hz, H-3IV), 5.76 (t, 1H, J4,3 10.0, J4,5 9.5 Hz, H-4III), 5.42 (t, 1H, J4,3 10.0, J4,5
9.5 Hz, H-4I), 5.36 (t, 1H, J3,4 10.0, J3,2 10.0 Hz, H-3III), 5.29 (t, 1H, J4,3 10.0, J4,5 9.5 Hz, H-4II),
5.01 (d, 1H, J1,2 9.0 Hz, H-1I), 4.92 (d, 1H, J1,2 8.5 Hz, H-1II), 4.66-4.56 (m, 6H, H-1IV, H-2I,
H-2II, H-2III, H-2IV, H-5I), 4.47 (t, 1H, J5,4 9.5 Hz, H-5II), 4.26 (t, 1H, J5,4 10.0 Hz, H-5III), 4.22
II
III
(d, 1H, J1,2 8.0 Hz, H-1III), 4.18-4.10 (m, 2H, H-6aI, H-6a ), 3.90-3.84 (m, 2H, H-5IV, H-6a ),
24

II
I
3.80-3.71 (m, 3H, H-6b , H-6IV), 3.68 (d, 1H, 2J6b,6a 12.0 Hz, H-6b ), 3.56 (d, 1H, 2J6b,6a 12.0 Hz,
III
I
H-6b ), 1.67 (s, 3H, NHCOCH3 ), 1.04 (s, 9H, C(CH3)3); 13C NMR (CDCl3; 100 MHz): δ 171.1
I
(NHCOCH3 ), 166.8 (OCOAr), 166.6 (OCOAr), 166.5 (OCOAr), 166.3 (OCOAr), 166.2
(OCOAr), 165.04 (OCOAr), 164.96 (OCOAr), 164.89 (OCOAr), 158.4, 158.1, 157.7
II
III
IV
(NHCOCF3 , NHCOCF3 , NHCOCF3 ), 135.5 (Ar-CH), 135.3 (Ar-CH), 133.9 (Ar-CH), 133.8
(Ar-CH), 133.7 (Ar-CH), 133.6 (Ar-CH, Ar-C-), 133.5 (Ar-CH), 133.3 (Ar-CH), 131.5 (Ar-C-),
130.2 (Ar-CH), 130.1 (Ar-CH), 130.0 (Ar-CH), 129.9 (Ar-CH), 129.81 (Ar-CH), 129.77
(Ar-CH), 129.7 (Ar-CH), 129.1 (Ar-C-), 128.9 (Ar-C-), 128.71 (Ar-C-), 128.67 (Ar-C-), 128.61
(Ar-CH), 128.57 (Ar-CH, Ar-C-), 128.51 (Ar-CH), 128.47 (Ar-CH), 128.4 (Ar-CH, Ar-C-),
128.3 (Ar-CH), 128.23 (Ar-CH), 128.15 (Ar-C-), 127.55 (Ar-CH), 127.47 (Ar-CH), 117.0,
II
III
IV
116.9, 116.7, 114.2, 114.1, 113.8 (NHCOCF3 , NHCOCF3 , NHCOCF3 ), 103.8 (C-1IV), 103.1
(C-1III), 101.5 (C-1II), 89.1 (C-1I), 77.1 (C-5IV), 74.8 (C-5I), 73.8 (C-5III), 73.1 (C-5II), 72.9
(C-6II), 72.8 (C-3I), 72.49 (C-3II), 72.43 (C-6III), 72.37 (C-3III), 71.7 (C-3IV), 71.5 (C-6I), 71.0
(C-4I), 70.7 (C-4II), 69.5 (C-4III), 69.0 (C-4IV), 64.3 (C-6IV), 55.2 (C-2IV), 55.1 (C-2III), 54.5
I
(C-2II), 53.5 (C-2I), 26.7 (C(CH3)3), 22.6 (NHCOCH3 ), 18.9 (C(CH3)3); HRMS: Calcd for
C104H94F9N7NaO28Si+ [M + Na]+ m/z = 2110.5665. Found: 2110.5629.
3.15 6-O-[6-O-(6-O-[2-Trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl]-
2-trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl)-2-trifluoroacetamido-
3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl]-2-acetamido-3,4-di-O-benzoyl-2-deoxy-β-D-
glucopyranosyl azide (16)
A solution of tetrasaccharide 15 (30.2 mg, 0.020 mmol) in anhydrous THF (5 mL), HOAc
(16.6 µL, 0.290 mmol) and TBAF (0.15 mL, 0.15 mmol) was stirred at room temperature for 24
h. The reaction mixture was diluted with Et2O (50 mL) and washed with satd NH4Cl solution
25

(10 mL). The organic layer was dried over anhydrous MgSO4, filtered and the solvent removed.
The residue was purified by column chromatography over silica gel using an Et2O:light
petroleum mixture (90%) as the eluent. The main fraction was collected and the solvent
removed to give 16 as a white solid: 26.8 mg, quant.; mp 163-165 °C (dec.); [α]D24-58.4° (c 0.17,
CH2Cl2); Rf 0.22 (100% Et2O); λabs (CH2Cl2)/nm : 234 (log ε/M-1cm-1, 5.00), 276 (3.93), 284
(3.84); IR (neat); v 3323 (NH), 2118 (N3), 1720 and 1271 (ester), 1066 and 690 (C-O, C-F), 707
cm-1 (Ar); 1H NMR (CDCl3; 500 MHz): δ 7.99-7.97 (AA’BB’C, 4H, Ar-H), 7.96-7.87
(AA’BB’C, 12H, Ar-H), 7.55-7.50 (AA’BB’C, 3H, Ar-H), 7.47-7.42 (AA’BB’C, 7H, Ar-H),
7.41-7.35 (AA’BB’C, 7H, Ar-H), 7.32-7.24 (AA’BB’C, 5H, Ar-H), 7.19-7.16 (AA’BB’C, 2H,
Ar-H), 5.85 (t, 1H, J3,2 10.5, J3,4 9.9 Hz, H-3II), 5.79 (t, 1H, J3,2 10.3, J3,4 10.0 Hz, H-3I), 5.72-
5.66 (m, 2H, H-3III, H-3IV), 5.57 (t, 1H, J4,5 9.7, J4,3 9.5 Hz, H-4III), 5.42 (t, 1H, J4,3 9.5, J4,5
9.5 Hz, H-4IV), 5.32 (t, 1H, J4,3 9.8, J4,5 9.8 Hz, H-4I), 5.25 (t, 1H, J4,3 9.8, J4,5 9.7 Hz, H-4II),
4.97 (d, 1H, J1,2 9.4 Hz, H-1I), 4.83 (d, 1H, J1,2 8.3 Hz, H-1II), 4.75 (d, 1H, J1,2 8.5 Hz, H-1III),
4.62 (d, 1H, J1,2 8.4 Hz, H-1IV), 4.47 (br t, 2H, H-2III, H-5I), 4.40-4.30 (m, 4H, H-2I, H-2II, H-2IV,
I
II
H-5II), 4.17 (br td, 1H, J5,4 10.0, J5,6a 2.5, J5,6b 2.0 Hz, H-5III), 4.03-3.99 (m, 2H, H-6a , H-6a ),
II
III
I
3.89-3.84 (m, 2H, H-6b , H-6a ), 3.77 (br dd, 1H, 2J6b,6a 12.0, J6b,5 1.5 Hz, H-6b ), 3.71-3.65 (m,
III
IV
IV
I
3H, H-5IV, H-6b , H-6a ), 3.56 (br d, 1H, H-6b ), 1.80 (s, 3H, NHCOCH3 ); 13C NMR (CDCl3;
I
100 MHz): δ 171.4 (NHCOCH3 ), 166.5 (OCOAr), 166.44 (OCOAr), 166.37 (OCOAr), 166.2
(OCOAr), 166.1 (OCOAr), 166.03 (OCOAr), 165.96 (OCOAr), 165.5 (OCOAr), 158.3, 158.1,
II
III
IV
157.9, 157.7 (NHCOCF3 , NHCOCF3 , NHCOCF3 ), 133.8 (Ar-CH), 133.7 (Ar-CH), 133.6
(Ar-CH), 133.5 (Ar-CH), 133.4 (Ar-CH), 133.3 (Ar-CH), 129.94 (Ar-CH), 129.92 (Ar-CH),
129.86 (Ar-CH), 129.85 (Ar-CH), 129.78 (Ar-CH), 129.76 (Ar-CH), 128.9 (Ar-C-), 128.71
(Ar-C-), 128.65 (Ar-CH), 128.6 (Ar-C-), 128.55 (Ar-CH), 128.52 (Ar-CH, Ar-C-), 128.50
26

(Ar-CH), 128.43 (Ar-C-), 128.40 (Ar-CH), 128.34 (Ar-CH), 128.30 (Ar-CH), 128.28 (Ar-CH,
II
III
IV
Ar-C-), 117.0, 114.2 (NHCOCF3 , NHCOCF3 , NHCOCF3 ), 102.4 (C-1III), 102.3 (C-1IV),
101.3 (C-1II), 88.8 (C-1I), 74.8 (C-5IV), 74.7 (C-5I), 73.7 (C-5III), 73.1 (C-5II), 72.8 (C-3I), 72.3
(C-3II, C-3III), 71.9 (C-6II), 71.7 (C-3IV), 70.9 (C-6III), 70.6 (C-4I, C-4II, C-6I), 70.3 (C-4III), 69.6
I
(C-4IV), 61.1 (C-6IV), 54.7 (C-2III), 54.6 (C-2IV), 54.4 (C-2II), 53.5 (C-2I), 22.5 (NHCOCH3 );
HRMS: Calcd for C88H76F9N7NaO28+ [M+Na]+ m/z = 1872.4487. Found: 1872.4494.
3.16 6-O-[6-O-(6-O-[6-O-(2-Trifluoroacetamido-3,4,6-tri-O-benzoyl-2-deoxy-β-D-
glucopyranosyl)-2-trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl]-2-
trifluoroacetamido-3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl)-2-trifluoroacetamido-
3,4-di-O-benzoyl-2-deoxy-β-D-glucopyranosyl]-2-acetamido-3,4-di-O-benzoyl-2-deoxy-β-D-
glucopyranosyl azide (17)
A solution of glycosyl acceptor 16 (18.7 mg, 0.010 mmol), glycosyl donor 6 (14.8 mg, 0.020
mmol), NIS (5.8 mg, 0.03 mmol) and anhydrous CH2Cl2 (2 mL) was stirred under nitrogen at
room temperature for 30 min. TMSOTf (0.400 µL, 2.34 µmol) was added to the reaction
mixture and stirring was continued for 21 h. Et3N (20.0 µL) was added to quench the reaction
and the solvent was removed. The residue was purified by column chromatography over silica
gel using an EtOAc:light petroleum mixture (50%). The main fraction was collected and the
solvent removed to give 17 as a white solid: 16.6 mg, 68%; mp 161-163 °C (dec.); [α]D23-104.2°
[c 1.41, CH2Cl2/MeOH (1:1)]; Rf 0.51 (60% EtOAc/light petroleum); λabs [CH2Cl2/MeOH
(1:1)]/nm : 238 (log ε/M-1cm-1, 5.63), 275 (4.79), 284 (4.69); IR (neat); v 3323 (NH), 2118 (N3),
1720 and 1268 (ester), 1065 and 690 (C-O, C-F), 707 cm-1 (Ar); 1H NMR (CDCl3/CD3OD; 500
MHz): δ 8.10-8.09 (AA’BB’C, 2H, Ar-H), 7.98-7.96 (AA’BB’C, 6H, Ar-H), 7.95-7.93
(AA’BB’C, 4H, Ar-H), 7.89-7.88 (AA’BB’C, 6H, Ar-H), 7.54-7.47 (AA’BB’C, 3H, Ar-H),
27

7.45-7.28 (AA’BB’C, 24H, Ar-H), 7.25-7.22 (AA’BB’C, 4H, Ar-H), 7.16-7.12 (AA’BB’C, 4H,
Ar-H), 7.08-7.05 (AA’BB’C, 2H, Ar-H), 6.08 (t, 1H, J3,2 9.8, J3,4 9.7 Hz, H-3III), 5.84 (t, 1H, J3,2
10.4, J3,4 10.3 Hz, H-3II), 5.82 (t, 1H, J3,4 10.2, J3,2 10.2 Hz, H-3I), 5.68 (t, 1H, J4,5 9.8, J4,3
9.7 Hz, H-4III), 5.62 (t, 1H, J4,5 9.7, J4,3 9.2 Hz, H-4IV), 5.59 (t, 1H, J4,5 9.8, J4,3 9.4 Hz, H-4V),
5.53 (t, 1H, J3,2 10.5, J3,4 9.1 Hz, H-3IV), 5.48 (t, 1H, J3,2 10.7, J3,4 9.2 Hz, H-3V), 5.23 (t, 1H, J4,5
9.8, J4,3 9.8 Hz, H-4I), 5.09 (t, 1H, J4,3 9.9, J4,5 9.8 Hz, H-4II), 5.04 (d, 1H, J1,2 9.3 Hz, H-1I), 4.90
(d, 1H, J1,2 8.4 Hz, H-1II), 4.74 (td, 1H, J5,4 10.3, J5,6a 2.4 Hz, H-5I), 4.71-4.65 (m, 2H, H-1III,
H-2III), 4.59-4.54 (m, 4H, H-1IV, H-2V, H-5II, H-5III), 4.51-4.44 (m, 4H, H-2I, H-2II, H-2IV,
V
I
II
H-6aV), 4.36 (d, 1H, J1,2 8.4 Hz, H-1V), 4.16-4.06 (m, 4H, H-6b , H-6a , H-6a , H-6aIII), 4.03 (td,
J5,4 10.0, J5,6b 1.9 Hz, H-5IV), 3.96 (ddd, J5,4 10.0, J5,6a 4.9, J5,6b 2.4 Hz, H-5V), 3.90 (dd, 1H,
IV
I
III
II
2J6a,6b 12.6, J6a,5 2.5 Hz, H-6a ), 3.58 (br dd, 2H, H-6b , H-6b ), 3.50 (br dd, 1H, H-6b ), 3.24
IV
I
(dd, 1H, 2J6b,6a 12.6, J6b,5 1.7 Hz, H-6b ), 1.83 (s, 3H, NHCOCH3 ); 13C NMR (CDCl3/CD3OD;
I
100 MHz): δ 172.0 (NHCOCH3 ), 166.54 (OCOAr), 166.43 (OCOAr), 166.33 (OCOAr), 166.29
(OCOAr), 166.27 (OCOAr), 166.1 (OCOAr), 165.87 (OCOAr), 165.77 (OCOAr), 165.1
II III
(OCOAr), 164.8 (OCOAr), 158.8, 158.6, 158.4, 158.2, 157.8 (NHCOCF3 , NHCOCF3 ,
IV
V
NHCOCF3 , NHCOCF3 ), 133.7 (Ar-CH), 133.6 (Ar-CH), 133.5 (Ar-CH), 133.4 (Ar-CH),
133.3 (Ar-CH), 133.2 (Ar-CH), 133.14 (Ar-CH), 133.08 (Ar-CH), 130.0 (Ar-CH), 129.8
(Ar-CH), 129.7 (Ar-CH), 129.66 (Ar-CH), 129.61 (Ar-CH), 129.58 (Ar-CH), 129.4 (Ar-CH),
129.02 (Ar-C-), 128.98 (Ar-C-), 128.88 (Ar-C-), 128.82 (Ar-C-), 128.78 (Ar-CH, Ar-C-), 128.75
(Ar-CH), 128.58 (Ar-C-), 128.46 (Ar-CH, Ar-C-), 128.41 (Ar-CH), 128.37 (Ar-C-), 128.31
(Ar-CH), 128.22 (Ar-CH), 128.19 (Ar-CH, Ar-C-), 128.09 (Ar-CH), 128.0 (Ar-C-), 116.87,
II
116.85, 116.6, 114.0, 113.73, 113.71, 113.2 (NHCOCF3 , NHCOCF3 , NHCOCF3 ,
III
IV
V
NHCOCF3 ), 103.4 (C-1IV), 103.1 (C-1V), 102.7 (C-1III), 100.8 (C-1II), 88.9 (C-1I), 74.03 (C-5I),
28

73.97 (C-5IV), 73.8 (C-6III), 73.6 (C-5III), 73.4 (C-6IV), 73.1 (C-5V, C-6II), 72.9 (C-3I), 72.4
(C-5II), 72.3 (C-3II), 71.8 (C-3III), 71.5 (C-3V), 71.4 (C-3IV, C-6I), 71.3 (C-4II, C-4III), 71.1 (C-4I),
70.3 (C-4IV), 70.0 (C-4V), 63.5 (C-6V), 54.8 (C-2IV), 54.5 (C-2III), 54.3 (C-2II, C-2V), 53.3 (C-2I),
I
22.1 (NHCOCH3 ); Anal. Calcd for C117H98F12N8O36: C, 58.07; H, 4.08; N, 4.63. Found: C,
57.94; H, 4.31; N, 4.40.
Acknowledgements.
Lucy Weaver is supported by an Australian Postgraduate Award.
Supporting Information Available. This material is available free of charge via the Internet at
http://pubs.acs.org.
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