Concise syntheses of β-GlcNAcp-(1→6)-α-Manp-(1→6) -Manp and its dimer, and β-GlcNAcp-(1→2)-α-Manp-(1→6)-Manp

Article abstract of DOI:10.1016/S0957-4166(03)00570-6

β-D-GlcNAcp-(1→6)-α-D-Manp-(1→6)-D-Manp and β-D-GlcNAcp-(1→2)-α-D-Manp-(1→6)-D-Manp were synthesized as their methyl glycosides in a regio- and stereoselective way, whereas an ethylene glycol-coupled dimer of the former was prepared in a convergent manner.

Full text of DOI:10.1016/S0957-4166(03)00570-6

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 14 (2003) 2595–2603
Concise syntheses of b-GlcNAcp-(1“6)-a-Manp-(1“6)-Manp
and its dimer, and b-GlcNAcp-(1“2)-a-Manp-(1“6)-Manp
Zuchao Ma, Jianjun Zhang and Fanzuo Kong*
Research Center for Eco-Environmental Sciences, Academia Sinica, PO Box 2871, Beijing 100085, PR China
Received 22 May 2003; accepted 9 July 2003
Abstract—b-
D
-GlcNAcp-(1“6)-a-
D
-Manp-(1“6)-
D
-Manp and b-
D
-GlcNAcp-(1“2)-a-D-Manp-(1“6)-D-Manp were synthesized
as their methyl glycosides in a regio- and stereoselective way, whereas an ethylene glycol-coupled dimer of the former was
prepared in a convergent manner.
© 2003 Elsevier Ltd. All rights reserved.
1. Introduction
glycosyl acceptor 3. Subsequent acetylation with acetic
anhydride in pyridine gave 4, and acetolysis with
HOAc–Ac2O–H2SO4 furnished 5. Selective 1-O-
The trisaccharide b-
D
-GlcNAcp-(1“6)-a- -Manp-(1“
D
6)- -Manp I is of interest since it has been observed as
D
deacetylation
with
NH3–MeOH
followed
by
trichloroacetimidation7 afforded the glycosyl donor 7.
Condensation of the donor 7 with the acceptor 3
afforded the (1“6)-linked disaccharide 8 (81.3%). The
regioselectivity of glycosylation was confirmed by ben-
zoylation to give 9 which showed in its 1H NMR
increased branching of asparagine-linked oligosaccha-
rides in murine and human tumor cells1 and has been
associated with malignancy.2 It has also been reported
that the regio isomer of the trisaccharide b-
D
-Glc-
NAcp-(1“2)-a-
D
-Manp-(1“6)-
D
-Manp II can be
recognized3 by N-acetylglucosaminyl transferase V and
used as a transferase inhibitor.4 To the best of our
knowledge, there have been no reports so far dealing
with the synthesis of I even though it is important in
glycobiology research. Herein we report the regio- and
stereoselective syntheses of the trisaccharide I and its
ethylene glycol-linked dimer, and a concise synthesis of
the trisaccharide II as well.
spectrum a new signal at l 5.96 ppm with J3,4=J4,5
=
10.6 Hz for H-4 when compared to 8. Consecutively
selective 4%6%-de-O-acetylation of 9 with CH3COCl–
MeOH8 offered the disaccharide acceptor 10 in a satis-
factory yield (77.6%). Selective 6-O-glycosylation of 10
with
3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-b-D-
glucopyranosyl trichloroacetimidate 11 proceeded
smoothly giving the trisaccharide 12 (78.5%). Again,
the 6-O-glycosylation was verified by acetylation to
furnish 13 and the H NMR spectrum of 13 showed a
characteristic signal for H-4% at l 5.09 ppm with J3,4
1
2. Results and discussion
=
J
4,5=9.7 Hz. Treatment of 13 with hydrazine hydrate
We have developed a method5 for oligosaccharide syn-
thesis using unprotected or lightly protected sugars as
the glycosyl acceptors, with the result being a variety of
complex oligosaccharides that can be synthesized
efficiently.6 In the present research, concise syntheses of
the title oligosaccharides were achieved using this strat-
egy. Scheme 1 shows the syntheses of trisaccharides I
under reflux removed all of the acyl groups and subse-
quent acetylation with acetic anhydride in pyridine gave
the acetylated trisaccharide 14. Finally, deacetylation of
14 in a saturated solution of NH3 in methanol yielded
the target (1“6)-linked trisaccharide 15.
The trisaccharide 22 was also prepared in a concise way
as outlined in Scheme 1. Thus, coupling of the acceptor
and II. Methyl 4,6-O-benzylidene-a-D-mannopyran-
oside 1 was chosen as the starting material. Benzoyla-
tion of 1 followed by debenzylidenation afforded the
3 with 2-O-acetyl-3,4,6-tri-O-benzoyl-a-D-mannopyran-
osyl trichloroacetimidate 166b selectively afforded the
(1“6)-linked disaccharide 17 (82.2%). Benzoylation of
17 followed by 2%-O-deacetylation furnished the disac-
* Corresponding author. E-mail: fzkong@mail.rcees.ac.cn
0957-4166/$ - see front matter © 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0957-4166(03)00570-6

2596
Z. Ma et al. / Tetrahedron: Asymmetry 14 (2003) 2595–2603
Scheme 1. Reagents and conditions: (a) TMSOTf (0.01 equiv.), CH2Cl2, −20ꢀ0°C, 2–4 h; 81.3% for 8, 78.5% for 12, 82.2% for
17, 66.6% for 20, 82.3% for 25, 61.5% for 29, and 80.4% for 32, respectively. (b) BzCl–pyridine; 83.3%, 81.5%, 88.7% for 9, 18,
and 30, respectively. (c) 2–4% CH3COCl in CH2Cl2–CH3OH, rt, 12 h; 77.6% for 10, 74.7% for 19, 75.8% for 28, and 72.3% for
31, respectively. (d) Ac2O–pyridine; 84.7% for 13, 86.9% for 33. (e) i: EtOH–10% hydrazine hydrate, reflux, 48 h; ii: Ac2O–pyridine
(dry), rt, 12 h; 82.3%, 79.5%, 75.5% for 14, 21, and 34, respectively. (f) satd NH3–MeOH, rt, 72 h; 85.9%, 84.6%, 82.2% for 15,
22, and 35, respectively.
charide acceptor 19 (74.7%). Condensation of 19 with
11 offered the protected trisaccharide 20 in good yield
(66.6%). Reiteration of the dephthalylation, acetylation
and deacetylation gave the target trisaccharide 22.
such as those used to block glycoside hydrolases
through covalent modification of the active site, are not
yet well understood. Groups for the covalent modifica-
tion of active sites must be attached to the ligand in
such a way that they do not prevent specific binding.
The first reported spacer-modified ‘reducing’ disaccha-
Glycosyltransferases are specific with respect to both
the donor and the acceptor, and irreversible inhibitors,
ride consisted of two a- -glucose residues (1“4)-linked
D

Z. Ma et al. / Tetrahedron: Asymmetry 14 (2003) 2595–2603
2597
by an acyclic six-membered spacer and competitively
inhibited porcine pancreatic alpha-amylase.9 Also a
‘non-reducing’ spacer-modified disaccharide, which
mimicked part of the biantennary core structure of
N-linked glycoconjugates, was also reported.10 Dimal-
toside derivatives of ethane-1,2-diol having the a,a, a,b,
and b,b anomeric configurations at the linkage sites
were synthesized by Tsuchiya et al.11 In the present
research, an ethylene glycol-coupled dimer of the trisac-
charide I was also readily synthesized as indicated in
Scheme 2. First, the glycosyl donor 7 was coupled with
trityloxyethyl alcohol to afford 25 (82.3%). Detrityla-
tion followed by condensation with 7 offered a glycol-
coupled disaccharide 27 (88.7%). Compound 27 was
also obtainable by coupling of 23 with 2 equiv. of 7, but
a tedious separation of the product was necessary.
Selective removal of the acetyl groups in 2%
CH3COCl–MeOH furnished 28 in satisfactory yield
(75.8%). Subsequent coupling of 28 with 7 yielded
tetrasaccharide 29 in a fair yield (61.5%). It was noted
Scheme 2. Reagents and conditions: (a) TMSOTf (0.01 equiv.), CH2Cl2, −20ꢀ0°C, 2–4 h; 81.3% for 8, 78.5% for 12, 82.2% for
17, 66.6% for 20, 82.3% for 25, 61.5% for 29, and 80.4% for 32, respectively. (b) BzCl–pyridine; 83.3%, 81.5%, 88.7% for 9, 18,
and 30, respectively. (c) 2–4% CH3COCl in CH2Cl2–CH3OH, rt, 12 h; 77.6% for 10, 74.7% for 19, 75.8% for 28, and 72.3% for
31, respectively. (d) Ac2O–pyridine; 84.7% for 13, 86.9% for 33. (e) i: EtOH–10% hydrazine hydrate, reflux, 48 h; ii: Ac2O–pyridine
(dry), rt, 12 h; 82.3%, 79.5%, 75.5% for 14, 21, and 34, respectively. (f) satd NH3–MeOH, rt, 72 h; 85.9%, 84.6%, 82.2% for 15,
22, and 35, respectively.

2598
Z. Ma et al. / Tetrahedron: Asymmetry 14 (2003) 2595–2603
that in the preparation of 29, the molar ratio of 7:28
was 1:1, otherwise, for example with 2:1, pentasaccha-
ride 36 was the major product. Benzoylation of 29
followed by deacetylation gave the tetrasaccharide
acceptor 31 (72.3%). Condensation of the acceptor 31
with the donor 11 selectively gave the (1“6)-linked
oligosaccharide 32 (80.4%). Acetylation of 32 afforded
2:1, 150 mL). After stirring at rt for 1 h, TLC (2:1
petroleum ether–EtOAc) indicated that the reaction
was complete. The solvents were evaporated to give the
crude product 6 as a syrup. Compound 6 was then
dissolved in CH2Cl2 (60 mL), after which CCl3CN (4
mL, 0.04 mol) and DBU (0.5 mL, 3.3 mmol) were
added. The reaction mixture was stirred for 2 h, at the
end of which TLC (2:1 petroleum ether–EtOAc) indi-
cated that the reaction was complete. Concentration of
the reaction mixture, followed by purification of the
crude product on a silica gel column with 2.5:1
petroleum ether–EtOAc as the eluent, furnished the
donor 7 (9.57 g, 77.6% for four steps) as a foamy solid.
[h]D=−68.7 (c 1.0, CHCl3); 1H NMR (400 MHz,
CDCl3): l 8.09ꢀ7.26 (m, 10H, 2Ph), 6.51 (d, 1H,
1
33, with the H NMR data of 33 showing a characteris-
tic signal for H%-4 at l 5.32 ppm with J3,4=J4,5=9.9
Hz. Deprotection of 33 was completed by dephthalyla-
tion, acetylation, and then by deacylation.
Bioassay of the samples 15, 22, and 35 is in progress,
and the results will be reported in due course.
J
1,2=2.0, H-1), 5.85 (dd, 1H, J1,2=2.0, J2,3=3.1, H-2),
3. Conclusion
5.81 (dd, 1H, J3,4=J4,5=9.8, H-4), 5.75 (dd, 1H, J2,3
=
3.1, J3,4=10.1, H-3), 4.39ꢀ4.25 (m, 3H, H-5, H-6),
2.14 (s, 3H, COCH3), 2.00 (s, 3H, COCH3). Anal. calcd
for C21H26Cl3NO9: C, 52.74; H, 4.26. Found: C, 52.99;
H, 4.34.
In summary, the efficient syntheses of b-
(1“6)-a- -Manp-(1“6)- -Manp I and its glycol-cou-
pled dimer, and b- -GlcNAcp-(1“2)-a- -Manp-
(1“6)-
D-GlcNAcp-
D
D
D
D
D
-Manp II were achieved with lightly protected
mannose derivatives as the acceptors.
4.3. Methyl 4,6-di-O-acetyl-2,3-di-O-benzoyl-a-D-
mannopyranosyl-(1“6)-2,3-di-O-benzoyl-a-D-
mannopyranoside 8
4. Experimental
To a cooled solution (−20°C) of 3 (0.60 g, 1.50 mmol)
and 7 (1.02 g, 1.65 mmol) in anhydrous CH2Cl2 (25
mL) was added TMSOTf (30 mL, 0.17 mmol). The
mixture was stirred at this temperature for 2 h, and
then quenched with Et3N (two drops). The solvents
were evaporated in vacuo to give a residue, which was
purified by silica gel column chromatography (3:1
petroleum ether–EtOAc) to give disaccharide 8 (1.05 g,
81.3%) as a foamy solid. [h]D=−28.5 (c 1.0, CHCl3); 1H
NMR (400 MHz, CDCl3): l 8.11ꢀ7.34 (m, 20H, 4Ph),
5.78ꢀ5.66 (m, 4H, H-2,2%,3,4%), 5.57 (dd, 1H, J2%,3%=3.5,
J3%,4%=9.8, H-3%), 5.22 (d, 1H, J1%,2%=1.3, H-1%), 4.93 (d,
1H, J1,2=1.6, H-1), 4.37ꢀ4.18 (m, 5H), 4.03ꢀ3.95 (m,
2H), 3.51 (s, 3H, CH3O), 2.17 (bs, 1H, OH), 2.12 (s,
3H, COCH3), 1.96 (s, 3H, COCH3); 13C NMR (100
MHz, CDCl3): l 170.6, 169.7 (2C, 2CH3CO), 167.0,
165.5, 165.2, 165.1 (4C, 4PhCO), 133.4ꢀ128.2 (PhCO),
98.7, 97.5 (2C, 2C-1), 73.4, 71.5, 70.4, 70.2, 70.0, 68.6,
66.4, 66.2, 66.1, 62.4 (C-2ꢀ6, some signals overlapped),
55.2 (CH3O), 20.6 (CH3CO). Anal. calcd for
C45H44O17: C, 63.08; H, 5.18. Found: C, 63.29; H, 5.13.
4.1. General methods
Optical rotations were determined at 25°C with a
Perkin–Elmer Model 241-Mc automatic polarimeter.
1H and 13C NMR spectra were recorded with Bruker
1
ARX 400 spectrometers (400 MHz for H, 100 MHz
for 13C) for solutions in CDCl3 or D2O as indicated.
Chemical shifts are given in ppm downfield from inter-
nal Me4Si. Mass spectra were measured using a
MALTI-TOF-MS with CCA as the matrix or recorded
with a VG PLATFORM mass spectrometer using the
ESI mode. Thin-layer chromatography (TLC) was per-
formed on silica gel HF254 with detection by charring
with 30% (v/v) H2SO4 in MeOH or in some cases by a
UV detector. Column chromatography was conducted
by elution of a column (16×240 mm, 18×300 mm,
35×400 mm) of silica gel (100–200 mesh) with EtOAc–
petroleum ether (60–90°C) as the eluent. Solutions were
concentrated at <60°C under reduced pressure.
4.2. Methyl 4,6-di-O-acetyl-2,3-di-O-benzoyl-a-D-
mannopyranosyl trichloroacetimidate 7
4.4. Methyl 4,6-di-O-acetyl-2,3-di-O-benzoyl-a-D-
mannopyranosyl-(1“6)-2,3,4-tri-O-benzoyl-a-D-
Compound 312 was obtained from 113 by benzoylation
followed by debenzylidenation. To a solution of 3 (8.04
g, 0.02 mol) in pyridine (40 mL) was added Ac2O (25
mL, 0.25 mol). The reaction mixture was stirred at rt
for 12 h and then concentrated to give the crude
product 4 as a syrup, to which an acetolysis reagent
(HAc:Ac2O:H2SO4=10:10:2, 44 mL) was directly
added. The reaction mixture was stirred at rt overnight,
then poured onto ice (400 g). To the mixture was added
CH2Cl2 (500 mL) and then washed with saturated aq
NaHCO3 and water. Concentration of the organic layer
gave the crude product 5 as a syrup, which was dis-
solved in satd NH3–MeOH–toluene (MeOH:toluene=
mannopyranoside 9
To a solution of 8 (857 mg, 1.0 mmol) in pyridine (10
mL) was added benzoyl chloride (0.14 mL, 1.2 mmol).
After stirring the mixture overnight at rt, TLC (2:1
petroleum ether–EtOAc) indicated that the reaction
had gone to completion. Methanol (five drops) was
added to the reaction mixture and allowed to stir for 10
min. Water (20 mL) was then added, and the mixture
extracted with CH2Cl2 (3×20 mL). The extract was
washed with 1 M HCl and saturated aq NaHCO3, dried
over Na2SO4 and concentrated. Purification by flash
chromatography (3:1 petroleum ether–EtOAc) gave 9

Z. Ma et al. / Tetrahedron: Asymmetry 14 (2003) 2595–2603
2599
as a foamy solid (801 mg, 83.3%). [h]D=−98.7 (c 1.0,
CHCl3); 1H NMR (400 MHz, CDCl3): l 8.17ꢀ7.26 (m,
25H, 5Ph), 5.96 (dd, 1H, J3,4=J4,5=10.6, H-4), 5.91
(dd, 1H, J2,3=3.3, J3,4=10.6, H-3), 5.77ꢀ5.66 (m, 4H),
5.09 (d, 1H, J1,2=1.1, H-1%), 5.02 (d, 1H, J1,2=1.1,
H-1), 4.36 (m, 1H, H-5), 4.22ꢀ4.16 (m, 2H), 4.07ꢀ4.02
(m, 2H), 3.75 (m, 1H, H-6b), 3.60 (s, 3H, CH3O), 2.00
(s, 3H, CH3CO), 1.99 (s, 3H, CH3CO). Anal. calcd for
C52H48O18: C, 65.00; H, 5.03. Found: C, 65.18; H, 4.97.
97.3 (3C, 3C-1), 72.9, 71.8, 71.3, 70.6, 70.3, 70.1, 70.0,
69.2, 69.1, 68.9, 66.9, 66.3, 65.9, 61.9, 54.3 (15C, C-2ꢀ
6), 55.5 (CH3O), 20.7, 20.5, 20.4 (CH3CO). Anal. calcd
for C68H63NO25: C, 63.11; H, 4.91. Found: C, 62.89; H,
4.82.
4.7. Methyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-b-
D
-glucopyranosyl-(1“6)-4-O-acetyl-2,3-di-O-
benzoyl-a-
benzoyl-a-
D
-mannopyranosyl-(1“6)-2,3,4-tri-O-
D
-mannopyranoside 13
4.5. Methyl 2,3-di-O-benzoyl-a-
D-mannopyranosyl-
(1“6)-2,3,4-tri-O-benzoyl-a- -mannopyranoside 10
D
To a solution of compound 12 (688 mg, 0.53 mmol) in
pyridine (10 mL) was added Ac2O (5 mL, 5 mmol). The
reaction mixture was stirred at rt for 12 h and then
concentrated to give the crude product, which was
purified by silica gel column chromatography (2:1
petroleum ether–EtOAc) to give trisaccharide 13 (602
mg, 84.7%) as a foamy solid. [h]D=−62.7 (c 1.0,
To a solution of 9 (777 mg, 0.81 mmol) in anhydrous
CH2Cl2 (10 mL) was added anhydrous MeOH (50 mL),
after which acetyl chloride (1.5 mL) was added to the
reaction mixture at 0°C. The solution was stoppered in
a flask and stirred at room temperature until TLC (3:1
petroleum ether–EtOAc) showed that the starting mate-
rial had disappeared. The solution was neutralized with
Et3N and then concentrated to dryness. The residue
was passed through a short silica gel column to give 10
(550 mg, 77.6%) as a foamy solid. [h]D=−80.7 (c 1.0,
1
CHCl3); H NMR (400 MHz, CDCl3) l 8.27ꢀ7.18 (m,
29H, 5Ph, Pth), 6.02 (dd, 1H, J3,4=J4,5=10.0, H-4),
5.88 (dd, 1H, J2,3=3.3, J3,4=10.0, H-3), 5.79 (dd, 1H,
J
3¦,4¦=9.3, J4¦,5¦=10.4, H-4¦), 5.72 (dd, 1H, J1%,2%=1.7,
J2%,3%=3.3, H-2%), 5.58 (dd, 1H, J2%,3%=3.3, J3%,4%=9.7,
H-3%), 5.43 (dd, 1H, J1,2=1.7, J2,3=3.3, H-2), 5.35 (d,
1H, J1¦,2¦=8.5, H-1¦), 5.28 (dd, 1H, J2,3=J3,4=10.2,
H-3¦), 5.09 (dd, 1H, J3%,4%=J4%,5%=9.7, H-4%), 4.98 (d, 1H,
J1%,2%=1.7, H-1%), 4.34ꢀ4.1 (m, 4H), 4.93 (dd, 1H,
1
CHCl3); H NMR (400 MHz, CDCl3) l 8.06ꢀ7.27 (m,
25H, 5Ph), 6.06 (dd, 1H, J3,4=J4,5=10.1, H-4), 5.90
(dd, 1H, J2,3=3.3, J3,4=10.1, H-3%), 5.73ꢀ5.65 (m,
3H), 5.07 (d, 1H, J1,2=1.0, H-1%), 5.07 (d, 1H, J1,2=1.1,
H-1), 4.34ꢀ4.27 (m, 2H), 4.05 (dd, 1H, J5,6b=4.5,
J
5,6a=1.8, J6a,6b=12.0, H-6a), 4.01 (m, 1H, H-5%), 3.89
(dd, 1H, J5%,6%a=1.6, J6%a,6%b=10.4, H-6%a), 3.83 (ddd, 1H,
J4¦,5¦=10.4, J5¦,6¦a=2.1, J5¦,6¦b=6.1, H-5¦), 3.72 (dd,
J
6a,6b=10.7, H-6b), 3.82ꢀ3.74 (m, 4H), 3.58 (s, 3H,
CH3O), 2.17 (bs, 2H, 2OH); 13C NMR (100 MHz,
CDCl3) l 166.5, 165.8, 165.6, 165.4, 165.2 (5C, 5
PhCO), 133.5ꢀ128.2 (PhCO), 98.7, 97.5 (2C, 2C-1),
72.8, 72.6, 70.3, 70.3, 70.1, 69.2, 67.1, 66.7, 66.3, 61.9
(10C, C-2ꢀ6), 55.5 (CH3O). Anal. calcd for C48H44O16:
C, 65.75; H, 5.06. Found: C, 65.84; H, 5.00.
1H, J5%,6%b=3.7, J6a%,6%b=10.4, H-6%b), 3.58 (s, 3H,
CH3O), 3.44 (dd, 1H, J5¦,6¦b=6.1, J6¦a,6¦b=10.3, H-6¦b),
3.25 (dd, 1H, J5¦,6¦a=2.1, J6¦a,6¦b=10.3, H-6¦a), 2.06 (s,
3H, CH3CO), 2.04 (s, 3H, CH3CO), 1.91 (s, 3H,
CH3CO), 1.88 (s, 3H, CH3CO). Anal. calcd for
C70H65NO26: C, 62.92; H, 4.90. Found: C, 62.73; H,
5.01.
4.6. Methyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-b-
D
-glucopyranosyl-(1“6)-2,3-di-O-benzoyl-a-
D
-
mannopyranosyl-(1“6)-2,3,4-tri-O-benzoyl-a-
mannopyranoside 12
D
-
4.8. Methyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-b-
D
-
glucopyranosyl-(1“6)-2,3,4-tri-O-acetyl-a-
D
-
mannopyranosyl-(1“6)-2,3,4-tri-O-acetyl-a-
D
-
To a cooled solution (−20°C) of 10 (519 mg, 0.59
mmol) and 11 (361 mg, 0.62 mmol) in anhydrous
CH2Cl2 (25 mL) was added TMSOTf (11 mL, 0.06
mmol). The mixture was stirred at this temperature for
2 h, and then quenched with Et3N (two drops). The
solvents were evaporated in vacuo to give a residue,
which was purified by silica gel column chromatogra-
phy (2:1 petroleum ether–EtOAc) to give trisaccharide
12 (602 mg, 78.5%) as a foamy solid. [h]D=−51.5 (c 1.0,
mannopyranoside 14
Trisaccharide 13 (563 mg, 0.42 mmol) was dissolved in
EtOH (50 mL) to which was added 100% hydrazine
hydrate (8 mL), and the solution allowed to reflux for
48 h. The solution was then concentrated, and the
residue was co-evaporated several times with toluene.
The residue was taken up in pyridine (10 mL) to which
was added Ac2O (5 mL). The solution was stirred for
12 h at rt and then evaporated to dryness. Purification
of the residue by column chromatography (EtOAc)
gave 14 (325 mg, 82.3% for two steps) as a foamy solid.
[h]D=+43.6 (c 1.0, CHCl3); 1H NMR (400 MHz,
CDCl3) l 6.23 (d, 1H, JH-C-N-H=8.9, NHAc), 5.40ꢀ
5.38 (m, 2H), 5.34ꢀ5.32 (dd, 1H, J2,3=3.3, J3,4=10.0,
H-3), 5.27ꢀ5.22 (m, 2H), 5.12ꢀ5.09 (m, 2H), 4.90 (d,
1H, J1%,2%=1.7, H-1%), 4.35 (d, 1H, J1,2=1.6, H-1), 4.35
(d, 1H, J1¦,2¦=8.5, H-1¦), 4.23ꢀ4.13 (m, 4H), 3.93ꢀ
3.91 (m, 2H), 3.75 (dd, 1H, J5%,6%b=3.8, J6%a,6%b=6.3,
H-6%b), 3.63ꢀ3.68 (m, 1H), 3.55 (dd, 1H, J5,6a=2.5,
1
CHCl3); H NMR (400 MHz, CDCl3) l 8.13ꢀ7.24 (m,
29H, 5Ph, Pth), 5.99 (dd, 1H, J3,4=J4,5=10.0, H-4),
5.85 (dd, 1H, J2,3=3.3, J3,4=10.0, H-3), 5.79 (dd, 1H,
J3¦,4¦=9.4, J4¦,5¦=10.5, H-4¦), 5.68 (dd, 1H, J1%,2%=1.5,
J2%,3%=3.1, H-2%), 5.44ꢀ5.36 (m, 3H, H-2, H-3%, H-1¦),
5.12 (dd, 1H, J2¦,3¦=J3¦,4¦=9.6, H-3¦), 4.95 (d, 1H,
J1%,2%=1.5 Hz, H-1%), 4.66 (d, 1H, J1,2=1.0 Hz, H-1),
4.31ꢀ4.08 (m, 5H), 3.85ꢀ3.79 (m, 4H), 3.64 (m, 1H),
3.55 (s, 3H, CH3O), 3.42 (m, 1H), 2.50 (bs, 1H, OH),
2.07 (s, 3H, CH3CO), 2.04 (s, 3H, CH3CO), 1.89 (s, 3H,
CH3CO); 13C NMR (100 MHz, CDCl3) l 170.6, 170.0,
169.4 (3C, 3CH3CO), 166.5, 165.7, 165.5, 165.4, 165.2
(5C, 5PhCO), 133.8ꢀ123.1 (PhCO, Pth), 99.0, 98.6,
J6a,6b=11.1, H-6a), 3.54 (s, 3H, CH3O), 3.34 (m, 1H,
H-6¦a), 2.17 (s, 3H, CH3CO), 2.10 (s, 3H, CH3CO),

2600
Z. Ma et al. / Tetrahedron: Asymmetry 14 (2003) 2595–2603
2.08 (s, 3H, CH3CO), 2.06 (s, 3H, CH3CO), 2.05 (s, 3H,
CH3CO), 2.03 (s, 3H, CH3CO), 2.02 (s, 3H, CH3CO),
2.00 (s, 3H, CH3CO), 1.99 (s, 3H, CH3CO), 1.98 (s, 3H,
CH3CO); 13C NMR (100 MHz, CDCl3) l 171.0, 170.8,
170.8, 170.5, 170.3, 170.3, 170.1, 170.0, 169.6, 169.4
(10C, 10CH3CO), 102.2, 98.4, 97.4 (3C, 3C-1), 73.4,
72.1, 69.6, 69.3, 69.3, 69.2, 69.2, 68.8, 68.6, 68.1, 66.8,
66.7, 66.3, 62.1, 53.9 (15C, C-2ꢀ6), 55.3 (1C, CH3O),
23.0ꢀ20.7 (CH3CO, some signals overlapped). Anal.
calcd for C39H55NO25: C, 49.95; H, 5.91. Found: C,
50.11; H, 6.00.
ration of 9 from 8, giving 18 (305 mg, 81.5%) as a
1
foamy solid. [h]D=−27.7 (c 1.0, CHCl3); H NMR (400
MHz, CDCl3) l 8.15ꢀ7.26 (m, 30H, 6Ph), 6.05 (dd,
1H, J3,4=J4,5=10.1, H-4), 5.94ꢀ5.90 (m3H), 5.74 (dd,
1H, J1,2=1.7, J2,3=3.2, H-2), 5.57 (s, 1H, H-2%), 5.02
(d, 1H, J1,2=1.5, H-1), 5.00 (d, 1H, J1,2=1.4, H-1%),
4.45ꢀ4.30 (m, 4H), 4.11 (dd, 1H, J5,6b=5.3, J6a,6b
=
10.8, H-6b), 3.75 (dd, 1H, J5,6a=1.9, J6a,6b=10.8, H-
6a), 3.60 (s, 3H, CH3O), 2.10 (s, 3H, CH3CO). Anal.
calcd for C57H50O18: C, 66.92; H, 4.93. Found: C,
67.08; H, 4.99.
4.9. Methyl 2-acetamido-2-deoxy-b-
(1“6)-a- -mannopyranosyl-(1“6)-a-
mannopyranoside 15
D-glucopyranosyl-
4.12. Methyl 3,4,6-tri-O-benzoyl-a-
D-mannopyranosyl-
D
D-
(1“6)-2,3,4-tri-O-benzoyl-a- -mannopyranoside 19
D
Deacetylation of compound 18 (282 mg, 0.28 mmol)
was carried out under the same conditions as those
used for the preparation of 10 from 9, giving 19 (202
mg, 74.7%) as a foamy solid. [h]D=−37.6 (c 1.0,
Trisaccharide 14 (290 mg, 0.31 mmol) was dissolved in
saturated NH3–MeOH (20 mL). After 96 h at rt, the
reaction mixture was concentrated, and the residue
purified by chromatography on Sephadex LH-20
(MeOH) to afford 15 (149 mg, 85.9%) as a foamy solid.
1
CHCl3); H NMR (400 MHz, CDCl3) l 8.12ꢀ7.25 (m,
1
30H, 6Ph), 6.10 (dd, 1H, J3,4=J4,5=10.1, H-4), 5.95ꢀ
5.90 (m, 2H), 5.77 (dd, 1H, J2,3=3.3, J3,4=10.1, H-3),
5.72 (dd, 1H, J1,2=1.7, J2,3=3.3, H-2), 5.07 (d, 1H,
[h]D=+36.2 (c 1.3, H2O); H NMR (400 MHz, D2O) l
4.75 (s, 1H, H-1%), 4.62 (s, 1H, H-1), 4.44 (d, 1H,
J
1¦,2¦=8.4 Hz, H-1¦), 4.06ꢀ3.32 (m, 18H), 3.27 (s, 3H,
CH3O), 1.93 (s, 3H, CH3CONH); 13C NMR (100 MHz,
D2O) l 174.6 (CH3CONH), 101.6, 101.2, 99.7 (3C,
3C-1), 76.0, 74.0, 71.5, 70.9, 70.8, 70.1, 69.0, 66.9, 66.7,
65.7, 60.9, 54.9 (15C, C2ꢀ6, some signals overlapped),
55.7 (CH3O), 22.4 (CH3CONH). Anal. calcd for
C21H37NO16: C, 45.08; H, 6.67. Found: C, 45.22; H,
6.73.
J1,2=1.7, H-1), 5.00 (d, 1H, J1%,2%=1.6, H-1%), 4.39ꢀ4.29
(m, 5H), 4.12 (dd, 1H, J5,6b=4.8, J6a,6b=11.0, H-6b),
3.78 (dd, 1H, J5,6a=2.2, J6a,6b=11.0, H-6a), 3.59 (s, 3H,
CH3O), 2.31 (bs, 1H, OH); 13C NMR (100 MHz,
CDCl3) l 166.0, 165.5, 165.5, 165.4, 165.4, 165.3 (6C,
6PhCO), 133.3ꢀ128.2 (PhCO), 99.6, 98.8 (2C, 2C-1),
72.5, 70.5, 70.1, 69.5, 69.1, 68.7, 66.9, 66.7, 66.2, 63.2
(10C, C-2ꢀ6, C-2%ꢀ6%), 55.5 (CH3O). Anal. calcd for
C55H48O17: C, 67.34; H, 4.93. Found: C, 67.08; H, 4.78.
4.10. Methyl 2-O-acetyl-3,4,6-tri-O-benzoyl-a-D-
mannopyranosyl-(1“6)-2,3-di-O-benzoyl-a-D-
mannopyranoside 17
4.13. Methyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-
b-
D
-glucopyranosyl-(1“2)-3,4,6-tri-O-benzoyl-a-D-
Compound 3 (185 mg, 0.46 mmol) and 16 (344 mg, 0.51
mmol) were coupled under the same conditions as those
used for the preparation of 8 from 3 and 7, giving 17
(348 mg, 82.2%) as a foamy solid. [h]D=+7.0 (c 1.0,
mannopyranosyl-(1“6)-2,3,4-tri-O-benzoyl-
a- -mannopyranoside 20
D
To a cooled solution (0°C) of 19 (190 mg, 0.19 mmol)
and 11 (123 mg, 0.21 mmol) in anhydrous CH2Cl2 (15
mL) was added TMSOTf (7 mL, 0.04 mmol). The
mixture was stirred at this temperature for 2 h, and
then quenched with Et3N (two drops). The solvents
were evaporated in vacuo to give a residue, which was
purified by silica gel column chromatography (2:1
petroleum ether–EtOAc) to give the trisaccharide 20
(180 mg, 66.6%) as a foamy solid. [h]D=−42.2 (c 0.5,
1
CHCl3); H NMR (400 MHz, CDCl3) l 8.11ꢀ7.26 (m,
25H, 5Ph), 5.94 (dd, 1H, J3%,4%=J4%,5%=9.9 Hz, H-4%),
5.87 (dd, 1H, J2%,3%=3.4, J3%,4%=9.9 Hz, H-3%), 5.66 (dd,
1H, J1%,2%=1.7, J2%,3%=3.4 Hz, H-2%), 5.62 (dd, 1H, J1,2
1.6, J2,3=3.3 Hz, H-2), 5.57 (dd, 1H, J2,3=3.3, J3,4
=
=
9.8, H-3), 5.14 (d, 1H, J1%,2%=1.7, H-1%), 4.92 (d, 1H,
J
J
1,2=1.6, H-1), 4.64ꢀ4.39 (m, 4H), 4.25 (dd, 1H,
5,6b=4.4, J6a,6b=11.3, H-6b), 4.01ꢀ3.92 (m, 2H), 2.90
(bs, 1H, OH), 2.12 (s, 3H, CH3CO); 13C NMR (100
MHz, CDCl3) l 169.6 (CH3CO), 166.9, 166.1, 165.5,
165.4, 165.3 (5C, 5PhCO), 98.8, 97.5 (2C, 2C-1),
133.3ꢀ128.2 (PhCO), 73.4, 71.6, 70.3, 69.8, 69.7, 68.6,
67.2, 66.3, 66.0, 63.3 (10C, C-2ꢀ6), 55.2 (CH3O), 20.6
(CH3CO). Anal. calcd for C50H46O17: C, 65.35; H, 5.05.
Found: C, 65.66; H, 5.13.
1
CHCl3); H NMR (400 MHz, CDCl3) l 8.02ꢀ7.15 (m,
34H, 6Ph, Pth), 6.07 (dd, 1H, J3,4=J4,5=10.2, H-4),
5.87 (dd, 1H, J2,3=3.4, J3,4=10.2, H-3), 5.74 (dd, 1H,
J
1,2=1.7, J2,3=3.3, H-2), 5.73ꢀ5.69 (m, 2H), 5.57 (dd,
1H, J1%,2%=1.3, H-1%), 5.38 (d, 1H, J1¦,2¦=8.5, H-1¦), 4.58
(dd, 1H, J1%,2%=1.7, J’2%,3%=3.2, H-2%), 4.41 (dd, 1H,
J1¦,2¦=8.5, J2¦,3¦=10.9, H-2¦), 4.31 (m, 1H, H-5), 4.02
(m, 1H, H-5%), 3.97ꢀ3.90 (m, 2H), 3.76ꢀ3.61 (m, 5H),
3.60 (s, 3H, CH3O), 1.96 (s, 3H, CH3CO), 1.84 (s, 3H,
CH3CO), 1.79 (s, 3H, CH3CO); 13C NMR (100 MHz,
CDCl3) l 170.3, 170.0, 169.2 (3C, 3CH3CO), 165.6,
165.6, 165.5, 165.5, 165.4, 164.9 (6C, 6PhCO), 134.0ꢀ
125.2 (PhCO, Pth), 98.9, 97.7, 96.9 (3C, 3C-1), 74.5,
71.7, 70.7, 70.5, 70.4, 70.2, 69.2, 68.8, 68.2, 66.5, 66.3,
4.11. Methyl 2-O-acetyl-3,4,6-tri-O-benzoyl-a-D-
mannopyranosyl-(1“6)-2,3,4-tri-O-benzoyl-a-D-
mannopyranoside 18
Compound 17 (336 mg, 0.37 mmol) was benzoylated
under the same conditions as those used for the prepa-

Z. Ma et al. / Tetrahedron: Asymmetry 14 (2003) 2595–2603
2601
65.9, 63.2, 61.8, 54.3 (15C, C-2ꢀ6), 55.5 (CH3O), 29.6,
20.4, 20.4 (CH3CO). Anal. calcd for C75H67NO26: C,
64.42; H, 4.83. Found: C, 64.66; H, 4.91.
TMSOTf was added dropwise at −20°C with N2 protec-
tion. The reaction mixture was stirred for 2 h and then
neutralized with Et3N. Concentration of the reaction
mixture, followed by purification on a silica gel column,
gave 25 (1.07 g, 82.3%) as a foamy solid. [h]D=−45.3 (c
1.0, CHCl3); 1H NMR (CDCl3, 400 MHz): l 8.08ꢀ7.24
4.14. Methyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-b-
D
-glucopyranosyl-(1“2)-3,4,6-tri-O-acetyl-a-D-
mannopyranosyl-(1“6)-2,3,4-tri-O-acetyl-a-
mannopyranoside 21
D
-
(m, 25H, 5Ph), 5.86ꢀ5.69 (m, 3H), 5.13 (d, 1H, J1,2=
1.7, H-1), 4.39ꢀ4.19 (m, 3H, H-5, H-6a, H-6b), 3.98ꢀ
3.28 (m, 4H,2), 2.14 (s, 3H, CH3CO), 1.94 (s, 3H,
CH3CO). Anal. calcd for C45H42O11: C, 71.23; H, 5.58.
Found: C, 71.46; H, 5.68.
Trisaccharide 20 (167 mg, 0.12 mmol) was dissolved in
EtOH (20 mL) to which was added 100% hydrazine
hydrate (4 mL), and the solution heated to reflux for 48
h. The solution was then concentrated, and the residue
was co-evaporated several times with toluene. The
residue was taken up in pyridine (10 mL) to which was
added Ac2O (5 mL). The solution was stirred for 12 h
at rt and then evaporated to dryness. Purification of the
residue by column chromatography (EtOAc) gave 21
(89 mg, 79.5% for two steps) as a foamy solid. [h]D=
4.17. Hydroxyethyl 4,6-di-O-acetyl-2,3-di-O-benzoyl-a-
D
-mannopyranoside 26
Compound 25 (1.06 g, 1.40 mmol) was dissolved in
CH2Cl2 (10 mL), TsOH (110 mg) was added to the
solution, and the mixture allowed to be stirred at 30°C
overnight, after which it was neutralized with Et3N.
Concentration of the reaction mixture, followed by
purification on a silica gel column, gave 26 (618 mg,
85.5%) as a foamy solid. [h]D=−47.5 (c 0.6, CHCl3); 1H
NMR (CDCl3, 400 MHz): l 8.08ꢀ7.26 (m, 10H, 2Ph),
5.73ꢀ5.65 (m, 3H), 5.11 (d, 1H, J1,2=1.7, H-1), 4.35
(dd, 1H, J5,6b=5.6, J6a,6b=12.5, H-6b), 4.25ꢀ4.22 (m,
2H, H-5, H-6a), 3.92ꢀ3.74 (m, 4H, 2CH2), 2.15 (s, 3H,
CH3CO), 1.98 (s, 3H, CH3CO). Anal. calcd for
C26H28O11: C, 60.46; H, 5.46. Found: C, 60.63; H, 5.55.
1
+25.7 (c 1.0, CHCl3); H NMR (400 MHz, CDCl3) l
5.72 (d, JH-C-N-H=7.8, NHAc), 5.53 (dd, 1H, J3¦,4¦=9.2,
J4¦,5¦=10.5), 5.35ꢀ5.19 (m, 4H), 5.03 (d, 1H, J1,2=8.0,
H-1¦), 5.05ꢀ4.96 (m, 2H), 4.73 (d, 1H, J1,2=1.4, H-1%),
4.71 (d, 1H, J1,2=1.6, H-1), 4.27ꢀ3.92 (m, 7H), 3.81ꢀ
3.68 (m, 2H), 3.53ꢀ3.46 (m, 2H), 3.42 (s, 3H, CH3O),
2.16 (s, 3H, CH3CO), 2.09 (s, 3H, CH3CO), 2.07 (s, 3H,
CH3CO), 2.06 (s, 3H, CH3CO), 2.05 (s, 3H, CH3CO),
2.04 (s, 3H, CH3CO), 2.03 (s, 3H, CH3CO), 2.01 (s, 3H,
CH3CO), 1.99 (s, 6H, 2CH3CO), 1.94 (s, 3H, CH3CO);
13C NMR (100 MHz, CDCl3) l 170.9, 170.7, 170.3,
170.2, 170.0, 169.7, 169.6 (CH3CO, some signals over-
lapped), 98.8, 98.5, 97.7 (3C, 3C-1), 74.2, 71.9, 71.6,
70.2, 69.6, 69.3, 69.1, 66.8, 66.1, 62.9, 62.3, 55.9 (15C,
C-2ꢀ6), 55.3 (1C, CH3O), 29.8ꢀ20.8 (CH3CO). Anal.
calcd for C39H55NO25: C, 49.95; H, 5.91. Found: C,
49.77; H, 5.86.
4.18. 1,2-Di-[4,6-di-O-acetyl-2,3-di-O-benzoyl-a-D-
mannopyranosyloxy]ethane 27
Donor 7 (856 mg, 1.39 mmol) and acceptor 26 (597 mg,
1.16 mmol) were coupled under the same conditions as
those used for the preparation of 8 from 3 and 7, giving
27 (995 mg, 88.7%) as a foamy solid. [h]D=−78 (c 1.0,
CHCl3); 1H NMR (CDCl3, 400 MHz): l 8.09ꢀ7.26 (m,
20H, 4Ph), 5.80ꢀ5.73 (m, 4H), 5.68 (dd, 2H, J1,2=1.8,
4.15. Methyl 2-acetamido-2-deoxy-b-
(1“2)-a- -mannopyranosyl-(1“6)-a-
mannopyranoside 22
D-glucopyranosyl-
D
D
-
J2,3=2.6, 2H-2), 5.16 (d, 2H, J1,2=1.8, 2H-1), 4.55 (dd,
2H, J5,6b=4.2, J6a,6b=12.1, 2H-6b), 4.37ꢀ4.30 (m, 4H,
2H-5, 2H-6a), 4.13ꢀ3.78 (m, 4H, 2CH2), 2.18 (s, 6H,
2CH3CO), 1.85 (s, 6H, 2CH3CO); 13C NMR (100 MHz,
CDCl3) l 170.8, 169.8 (4C, 4CH3CO), 165.4, 165.3 (4C,
4PhCO), 113.6, 113.4, 130.0, 129.8, 129.5, 129.2, 128.6,
128.5 (PhCO, some signals overlapped), 97.4 (C-1),
70.3, 70.2, 69.0, 66.3, 66.0 (C-2ꢀ6), 62.5 (CH2), 20.9
(CH3CO), 20.6 (CH3CO). MALDI-TOF MS: Calcd for
C50H50NaO20 ([M+Na]): 993.92, found 993.28. Anal.
calcd for C50H50O20: C, 61.85; H, 5.19. Found: C,
62.02; H, 5.26.
Trisaccharide 21 (89 mg, 0.10 mmol) was dissolved in
saturated NH3–MeOH (20 mL). After 96 h at rt, the
reaction mixture was concentrated, and the residue
purified by chromatography on Sephadex LH-20
(MeOH) to afford 22 (45 mg, 84.6%) as a foamy solid.
1
[h]D=+42.5 (c 1.3, H2O); H NMR (400 MHz, D2O) l
4.79 (s, 1H, H-1%), 4.62 (d, 1H, J1,2=1.2, H-1), 4.44 (dd,
1H, J1¦,2¦=8.4, H-1¦), 3.99 (m, 1H, H-2), 3.90ꢀ3.31 (m,
17H), 3.27 (s, 3H, CH3O), 1.90 (s, 3H, CH3CONH); 13
C
NMR (100 MHz, D2O) l 174.9 (CH3CONH), 101.2,
99.7, 96.9 (3C, 3C-1), 76.5, 75.9, 73.4, 73.0, 71.0, 70.9,
70.0, 70.0, 69.7, 67.4, 66.5, 65.9, 61.7, 60.7, 54.9 (15C,
C-2ꢀ6, some signals overlapped), 55.5 (CH3O), 22.4
(CH3CONH). Anal. calcd for C21H37NO16: C, 45.08; H,
6.67. Found: C, 45.21; H, 6.59.
4.19. 1,2-Di-[2,3-di-O-benzoyl-a-D-mannopyranosyloxy]-
ethane 28
Compound 27 (914 mg, 0.94 mmol) was deacetylated
under the same conditions as those used for the prepa-
ration of 10 from 9, giving 28 (573 mg, 75.8%) as a
foamy solid. [h]D=−79.7 (c 1.5, CHCl3); 1H NMR
(CDCl3, 400 MHz): l 8.09ꢀ7.26 (m, 20H, 4Ph), 5.80
4.16. Trityloxyethyl 4,6-di-O-acetyl-2,3-di-O-benzoyl-a-
D
-mannopyranoside 25
(dd, 2H, J2,3=3.2, J3,4=9.8, 2H-3), 5.55 (dd, 2H, J1,2
=
Compound 7 (1.48 g, 2.40 mmol) and 24 (608 mg, 2
mmol) were dried together under high vacuum for 2 h
and then dissolved in anhydrous CH2Cl2 (30 mL).
1.8, J2,3=3.3, 2H-2), 5.10 (d, 2H, J1,2=1.8, 2H-1), 4.31
(dd, 2H, J3,4=J4,5=9.8, 2H-4), 4.15ꢀ4.20 (m, 8H),
3.78ꢀ3.68 (m, 4H), 3.09 (bs, 2H, 2OH), 1.85 (s, 6H,

2602
Z. Ma et al. / Tetrahedron: Asymmetry 14 (2003) 2595–2603
2CH3CO); 13C NMR (100 MHz, CDCl3) l 170.8, 169.8
(CH3CO), 165.4, 165.3 (PhCO), 113.6, 113.4, 130.0,
129.8, 129.5, 129.2, 128.6, 128.5 (PhCO, some signals
overlapped), 97.4 (C-1), 70.3, 70.2, 69.0, 66.3, 66.0
(C-2ꢀ6), 62.5 (CH2), 20.9 (CH3CO), 20.6 (CH3CO).
Anal. calcd for C42H42O16: C, 62.84; H, 5.27. Found: C,
62.98; H, 5.36.
10.2, 2H-3), 5.87ꢀ5.82 (m, 3H), 5.69 (dd, 2H, J3%,4%=
J4%,5%=9.7, 2H-4%), 5.27 (d, 4H, J1,2=1.3, 4H-1), 4.76 (m,
2H, H-5), 4.39ꢀ4.26 (m, 4H), 4.14 (d, 4H, J=9.5,
2CH2), 4.04ꢀ3.92 (m, 6H), 2.04 (s, 6H, 2CH3CO), 1.99
(s, 6H, 2CH3CO); 13C NMR (100 MHz, CDCl3) l
170.7, 169.9 (CH3CO), 165.5, 165.4, 165.3, 165.2
(PhCO), 113.4, 130.1, 133.0, 130.1, 129.9, 129.8, 129.7,
129.6, 129.4, 129.1, 128.8, 128.5, 128.4, 128.2, 128.1
(PhCO, some signals overlapped), 98.0, 97.6 (C-1),
70.7, 70.6, 70.3, 70.0, 68.7, 66.9, 66.7, 66.2, 66.0 (C-2ꢀ
6, some signals overlapped), 62.2 (CH2), 20.9
(CH3CO), 20.7 (CH3CO). Anal. calcd for C104H94O36:
C, 65.06; H, 4.94. Found: C, 64.88; H, 5.03.
4.20. 1,2-Di-[4,6-di-O-acetyl-2,3-di-O-benzoyl-a-D-
mannopyranosyl-(1“6)-2,3-di-O-benzoyl-a-D-
mannopyranosyloxy]ethane 29
Donor 7 (430 mg, 0.70 mmol) and acceptor 28 (560 mg,
0.70 mmol) were dried together under high vacuum for
2 h and then dissolved in anhydrous CH2Cl2 (25 mL).
TMSOTf (10 mL, 0.06 mmol) was added dropwise at
−20°C with N2 protection. The reaction mixture was
stirred for 2 h, during which time the temperature was
gradually warmed to ambient temperature. The mixture
was then neutralized with triethylamine and concen-
trated to dryness. Purification of the residue by column
chromatography on a silica gel column (1:1 petroleum
ether–EtOAc) gave recovered 28 (250 mg), pentasaccha-
ride 36 (153 mg, 33.8%) and the target product 29 (366
mg, 61.5%, calcd based on the donor) as foamy solids.
4.22. 1,2-Di-[2,3-di-O-benzoyl-a-
D
-mannopyranosyl-(1“
6)-2,3,4-tri-O-benzoyl-a-
D-mannopyranosyloxy]ethane
31
Compound 30 (324 mg, 0.17 mmol) was deacetylated
under the same condition as those used for the prepara-
tion of 10 from 9, giving 31 (214 mg, 72.3%) as a foamy
1
solid. [h]D=−108.5 (c 1.0, CHCl3); H NMR (CDCl3,
400 MHz): l 8.06ꢀ6.67 (m, 50H, 10Ph), 6.04 (dd, 2H,
J
3,4=J4,5=10.2, 2H-4), 5.94 (dd, 2H, J2,3=3.3, J3,4=
10.2, 2H-3), 5.78ꢀ5.70 (m, 6H), 5.31 (d, 2H, J1,2=1.5,
2H-1%), 4.93 (d, 2H, J1,2=1.0, 2H-1), 4.73 (m, 2H),
4.34ꢀ4.07 (m, 8H), 3.80ꢀ3.69 (m, 8H), 2.28 (bs, 4H,
4OH). Anal. calcd for C96H86O32: C, 65.82; H, 4.95.
Found: C, 65.55; H, 4.83.
1
For 29: [h]D=−54.6 (c 1.0, CHCl3); H NMR (CDCl3,
400 MHz): l 8.04ꢀ7.26 (m, 40H, 8Ph), 5.83ꢀ5.66 (m,
10H), 5.30 (s, 2H, 2H-1%), 5.11 (d, 2H, J1,2=1.1, 2H-1),
4.42ꢀ4.13 (m, 16H), 3.75 (m, 2H), 2.09 (s, 6H,
2CH3CO), 1.98 (s, 6H, 2CH3CO). MALDI-TOF MS:
calcd for C90H86NaO34 ([M+Na]): 1734.64, found
1733.92. Anal. calcd for C90H86O34: C, 63.15; H, 5.06.
Found: C, 62.98; H, 5.00. For 36: [h]D −71.2 (c 1.0,
4.23. 1,2-Di-[3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-b-
D
-glucopyranosyl-(1“6)-2,3-di-O-benzoyl-a-
D
-
mannopyranosyl-(1“6)-2,3,4-tri-O-benzoyl-a-
mannopyranosyloxy]ethane 32
D
-
1
CHCl3); H NMR (400 MHz, CDCl3) l 8.15ꢀ6.99 (m,
50H, 10Ph), 5.95ꢀ5.90 (m, 3H), 5.84ꢀ5.69 (m, 7H),
5.60 (s, 1H, H-1), 5.56 (m, 1H), 5.52 (d, 1H, J1,2=1.4,
H-1), 5.47 (dd, 1H, J1,2=1.6, J2,3=3.3, H-2), 5.46 (d,
1H, J1,2=1.5, H-1), 5.37 (dd, 1H, J2,3=3.3, J3,4=10.3,
H-3), 5.12 (d, 1H, J1,2=1.5, H-1), 5.11 (d, 1H, J1.2=1.5,
H-1), 4.69ꢀ4.20 (m, 19H), 3.78 (m, 1H), 2.16 (s, 3H,
CH3CO), 2.17 (s, 6H, 2CH3CO), 1.98 (s, 3H, CH3CO),
1.74 (s, 3H, CH3CO), 1.68 (s, 3H, CH3CO); 13C NMR
(100 MHz, CDCl3) l 170.8, 170.6, 170.0, 169.8
(CH3CO, some signals overlapped), 166.3, 165.7, 165.6,
165.5, 165.4, 165.3, 165.2, 165.0, 164.9, 164.1 (10C,
10PhCO), 133.3ꢀ127.9 (PhCO), 99.5, 98.2, 98.1, 97.2,
96.9 (5C, 5C-1), 73.4, 73.3, 72.2, 71.9, 70.7, 70.5, 70.4,
70.2, 70.0, 69.9, 69.1, 68.8, 66.6, 66.3, 66.2, 66.0, 65.6,
65.4, 62.5, 62.4 (C-2ꢀ6, CH2, some signals over-
lapped), 55.5 (CH3O), 20.8, 20.5, 20.4 (CH3CO, some
signals overlapped). Anal. calcd for C114H108O43: C,
63.21; H, 5.03. Found: C, 63.01; H, 4.95.
Donor 11 (146 mg, 0.25 mmol) was coupled with
acceptor 31 (201 mg, 0.12 mmol) to give trisaccharide
dimer 32 (238 mg, 80.4%) as a foamy solid. [h]D=−45.6
1
(c 1.0, CHCl3); H NMR (400 MHz, CDCl3) l 8.03ꢀ
6.86 (m, 58H, 10Ph, 2Pth), 6.05ꢀ6.00 (m, 2H), 5.93
(dd, 2H, J2,3=3.2, J3,4=10.2, 2H-3), 5.81ꢀ5.72 (m,
4H), 5.51 (dd, 2H, J1,2=1.6, J2,3=3.4, 2H-2), 5.44 (m,
2H), 5.35 (d, 2H, J1¦,2¦=8.5, 2H-1¦), 5.19 (d, 2H, J1,2
=
1.2, 2H-1%), 5.13 (dd, 2H, J2¦,3¦=J3¦,4¦=9.6, 2H-3¦), 4.80
(d, 2H, J1,2=1.6, 2H-1), 4.56ꢀ3.60 (m, 26H), 2.05 (s,
6H, 2CH3CO), 2.03 (s, 6H, 2CH3CO), 1.87 (s, 6H,
2CH3CO); 13C NMR (100 MHz, CDCl3) l 170.8, 170.2,
169.6 (CH3CO), 166.6, 165.9, 165.5, 165.3, 165.3
(PhCO), 133.8ꢀ123.1 (PhCO, Pth), 99.0, 98.6, 97.3
(C-1), 72.9, 71.8, 71.3, 70.6, 70.3, 70.1, 70.0, 69.2, 69.1,
68.9, 66.9, 66.3, 65.9 (C-2ꢀ6), 61.9 (CH2), 55.5
(CH3O), 20.7, 20.5, 20.4 (CH3CO). MALDI-TOF MS:
calcd for C136H124N2NaO50 ([M+Na]): 2609.45, found
2610.36. Anal. calcd for C136H124N2O50: C, 63.15; H,
4.83. Found: C, 63.37; H, 4.90.
4.21. 1,2-Di-[4,6-di-O-acetyl-2,3-di-O-benzoyl-a-D-
mannopyranosyl-(1“6)-2,3,4-tri-O-benzoyl-a-D-
mannopyranosyloxy-]ethane 30
4.24. 1,2-Di-[3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-b-
Compound 29 (353 mg, 0.21 mmol) was benzoylated
under the same condition as those used for the prepara-
tion of 10 from 9, giving 30 (351 mg, 88.7%) as a foamy
D
-glucopyranosyl-(1“6)-4-O-acetyl-2,3-di-O-
benzoyl-a-
benzoyl-a-
D
-mannopyranosyl-(1“6)-2,3,4-tri-O-
D
-mannopyranosyloxy]ethane 33
1
solid. [h]D=−84.6 (c 1.0, CHCl3); H NMR (CDCl3,
400 MHz): l 8.08ꢀ6.72 (m, 50H, 10Ph), 6.16 (dd, 2H,
Compound 32 (225 mg, 0.09 mmol) was acetylated
under the same condition as those used for the prepara-
J
3,4=J4,5=10.2, 2H-4), 6.02 (dd, 2H, J2,3=3.3, J3,4
=

Z. Ma et al. / Tetrahedron: Asymmetry 14 (2003) 2595–2603
2603
tion of 13 from 12, giving 33 (202 mg, 86.9%) as a
rt, the reaction mixture was concentrated, and the
residue purified by chromatography on Sephadex LH-
20 (MeOH) to afford 35 (48 mg, 82.2%) as a foamy
1
foamy solid. [h]D=−58.5 (c 1.3, CHCl3); H NMR (400
MHz, CDCl3) l 8.17ꢀ6.99 (m, 58H, 10Ph, 2Pth), 6.08
(dd, 2H, J3,4=J4,5=10.0, 2H-4), 5.99 (dd, 2H, J2,3=3.4,
1
solid. [h]D=+91.5 (c 1.0, H2O); H NMR (400 MHz,
J
3,4=10.0, 2H-3), 5.85 (dd, 2H, J1%,2%=1.5, J2%,3%=3.4,
D2O) l 4.86 (s, 4H, 4H-1), 4.54 (dd, 2H, J1¦,2¦=8.4,
2H-1¦), 4.15ꢀ3.45 (m, 40H), 2.04 (s, 6H, 2CH3CONH);
13C NMR (100 MHz, CDCl3) l 173.4 (CH3CONH),
101.7, 100.1, 99.6 (C-1), 76.1, 74.0, 71.5, 71.1, 71.0,
70.9, 70.1, 69.1, 66.9, 66.4, 65.9, 60.9, 55.7 (C-2ꢀ6,
some signals overlapped), 22.5 (CH3CONH). Anal.
calcd for C42H72N2O32: C, 45.16; H, 6.50. Found: C,
45.01; H, 6.42.
2H-2%), 5.81 (dd, 2H, J3¦,4¦=9.6, J4¦,5¦=10.7, 2H-4¦),
5.68 (dd, 2H, J2%,3%=3.4, J3%,4%=9.9, 2H-3%), 5.57 (dd, 2H,
J1,2=1.7, J2,3=3.3, 2H-2), 5.38 (d, 2H, J1¦,2¦=8.5, 2H-
1¦), 5.32 (dd, 2H, J3%,4%=J4%,5%=9.9, 2H-4%), 5.27 (d, 2H,
J1%,2%=1.5, 2H-1%), 5.11 (dd, 2H, J2¦,3¦=J3¦,4¦=9.6,, 2H-
3¦), 4.58 (m, 2H, 2H-5), 4.52 (d, 2H, J1,2=1.7, 2H-1),
4.35ꢀ4.29 (m, 6H), 4.12ꢀ4.06 (m, 4H), 3.97ꢀ3.95 (m,
4H), 3.92ꢀ3.82 (m, 8H), 3.57 (m, 2H), 3.46 (m, 2H),
2.05 (s, 6H, 2CH3CO), 2.03 (s, 6H, 2CH3CO), 1.89 (s,
6H, 2CH3CO), 1.85 (s, 6H, 2CH3CO). Anal. calcd for
Acknowledgements
C140H128N2O52: C, 62.97; H, 4.83. Found: C, 63.11; H,
4.92.
This work was supported by The Chinese Academy of
Sciences (KZCX3-J-08) and by The National Natural
Science Foundation of China (Projects 30070185 and
39970864).
4.25. 1,2-Di-[2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-b-
D
-glucopyranosyl-(1“6)-2,3,4-tri-O-acetyl-a-D-
mannopyranosyl-(1“6)-2,3,4-tri-O-acetyl-a-D-
mannopyranosyloxy-]ethane 34
References
Trisaccharide dimer 33 (185 mg, 0.07 mmol) was dis-
solved in EtOH (20 mL) after which was added 100%
hydrazine hydrate (4 mL) and the solution heated at
reflux for 48 h. The solution was then concentrated and
the residue co-evaporated several times with toluene.
The residue was taken up in pyridine (10 mL) to which
was added Ac2O (5 mL). The solution was stirred for
12 h at rt and then evaporated to dryness. Purification
of the residue by column chromatography (EtOAc)
gave 34 (98 mg, 75.5% for two steps) as a foamy solid.
[h]D=+96.7 (c 1.0, CHCl3); 1H NMR (400 MHz,
CDCl3) l 6.23 (d, 2H, JH-C-N-H=8.9, 2NHAc), 5.39ꢀ
5.15 (m, 16H), 5.09 (dd, 2H, J3,4=J4,5=9.2, 2H-4), 4.96
(d, 2H, J1%,2%=1.5, 2H-1%), 4.83 (d, 2H, J1,2=1.4, 2H-1),
4.45 (d, 2H, J1¦,2¦=8.4, 2H-1¦), 4.25ꢀ4.10 (m, 10H),
4.03ꢀ3.93 (m, 2H), 3.81 (m, 2H), 3.68ꢀ3.61 (m, 6H),
3.38 (dd, 2H, J5¦,6¦a=3.2, J6¦a,6¦b=11.2, 2H-6¦a), 2.14 (s,
12H, 4CH3CO), 2.09 (s, 12H, 4CH3CO), 2.03 (s, 6H,
2CH3CO), 2.02 (s, 6H, 2CH3CO), 2.00 (s, 6H,
2CH3CO), 1.99 (s, 6H, 2CH3CO), 1.96 (s, 12H,
4CH3CO). Anal. calcd for C78H108N2O50: C, 50.00; H,
5.81. Found: C, 50.21; H, 5.73.
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4.26. 1,2-Di-[2-acetamido-2-deoxy-b-
(1“6)-a- -mannopyranosyl-(1“6)-a-
pyranosyloxy-]ethane 35
D
-glucopyranosyl-
D
D-manno-
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Trisaccharide dimer 34 (98 mg, 0.05 mmol) was dis-
solved in saturated NH3–MeOH (20 mL). After 96 h at