Ring-opening polymerization of new 3-O-branched 1, 6-anhydro glucopyranose di- and trisaccharide monomers

Article abstract of DOI:10.1016/j.carres.2017.04.017

New 3-O-branched 1, 6-anhydro glucopyranose disaccharide monomers, 1, 6-anhydro-2, 4-di-O- benzyl-3-O-(2′, 3′, 4′, 6'-tetra-O-benzyl-α-D-mannopyranosyl)- (LGM 6) and -glucopyranosyl)-β-D- glucopyranose (LGG 7), and a trisaccharide monomer, 1, 6-anhydro-2,

Full text of DOI:10.1016/j.carres.2017.04.017

Accepted Manuscript
Ring-opening polymerization of new 3-O-branched 1, 6-anhydro glucopyranose di-
and trisaccharide monomers
Chaolumen Bai, Davaanyam Budragchaa, Takashi Yoshida, PhD, Professor
PII:
S0008-6215(17)30098-8
10.1016/j.carres.2017.04.017
CAR 7367
DOI:
Reference:
To appear in: Carbohydrate Research
Received Date: 11 February 2017
Revised Date: 10 April 2017
Accepted Date: 19 April 2017
Please cite this article as: C. Bai, D. Budragchaa, T. Yoshida, Ring-opening polymerization of new 3-O-
branched 1, 6-anhydro glucopyranose di- and trisaccharide monomers, Carbohydrate Research (2017),
doi: 10.1016/j.carres.2017.04.017.
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O
O
OBn
BnO
OBn
LGTBE
CH OBn
1
) Polymerization or
Copolymerization
with LGTBE
2
(OCH2
O
O
O
O
CH OH
OBn
BnO
2
( OCH2
OH
HO
O
)
O
OH
BnO
m
O
BnO
HO
O
2) Debenzylation
HO
)
OBn
HO
n
HO
LGM 6
OH
CH OBn
2
(OCH2
O
O
O
O
CH OH
2
( OCH2
OBn
O
BnO
OH
HO
)
O
O
BnO
m
OH
O
OBn
HO
)
OBn
HO
n
HO
OH
LGG 7
CH OBn
OH
CH OR
2
2
(
OCH
O
O
2
O
/
/
O
O
CH OBn OBn
2
CH OR OR
2
O
BnO
O
)
O
O
O
O
n
OBn
BnO
RO
OBn
OBn
OR
OR
OR
RO
OBn
LGMAL 8
OR
Ring-opening polymerization of new 3-O-branched 1, 6-anhydro glucopyranose di- and trisaccharide monomers
Bai Chaolumen, Davaanyam Budragchaa, Takashi Yoshida*
New 3-O-branched 1, 6-anhydro glucopyranose di- and trisaccharide monomers were synthesized and polymerized for
the first time. Although the disaccharide monomers gave 3-O-glucose or mannose branched polysaccharides in
moderate yields, the trisaccharide monomer 8 gave no polymer. The polymerizability of the 3-O-branched monomers
was lower than that of 4-O-branched monomers reported previously, probably due to the steric hindrance of the
branched bulky mono and disaccharide units at the 3-O position in 1, 6-anhydro glucopyranose.
Graphical Abstract

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Manuscript to Carbohydrate Research
Original research paper
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Ring-opening polymerization of new 3-O-branched 1, 6-anhydro glucopyranose
di- and trisaccharide monomers
a
b
a,
Bai Chaolumen , Davaanyam Budragchaa , Takashi Yoshida *
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Department of Bio and Environmental Chemistry, Kitami Institute of Technology, 165 Koen-cho, Kitami,
Hokkaido 090-8507, Japan
Laboratory of Metabolism and Biochemistry, Institute of Veterinary Medicine, University of Life Science,
Zaisan, Ulaanbaatar 17024, Mongolia
b
* Corresponding author at: Department of Bio and Environmental Chemistry, Kitami Institute of Technology, 165
Koen-cho, Kitami, Hokkaido 090-8507, Japan.
E-mail address: yoshida@chem.kitami-it.ac.jp (T. Yoshida)
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Author for correspondence: Takashi YOSHIDA, PhD
Professor
Department of Bio and Environmental Chemistry
Kitami Institute of Technology
165 Koen-cho, Kitami 090-8507, Japan
TEL and FAX: +81-157-26-9388
E-mail: yoshida@chem.kitami-it.ac.jp
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ABSTRACT
New 3-O-branched 1, 6-anhydro glucopyranose disaccharide monomers, 1, 6-anhydro-2, 4-di-O-
benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-
D-mannopyranosyl)- (LGM 6) and -glucopyranosyl)-β-D-
glucopyranose (LGG 7), and a trisaccharide monomer, 1, 6-anhydro-2, 4-di-O-benzyl-3-O-α-(2', 3',
6', 2", 3", 4", 6"-hepta-O-benzyl- α-D-maltopyranosyl)-β-D-glucopyranose (LGMAL 8), were
synthesized and polymerized. It was found that the 3-O-branched1, 6-anhydro disaccharide
monomers were polymerized. However, the polymerizability was lower than that of the
4-O-branched disaccharide monomers reported previously, and the trisaccharide monomer was not
polymerizable, probably due to the steric hindrance of the branched bulky mono and disaccharide
units at the 3-O position in 1, 6-anhydro glucopyranose. Debenzylation of the resulting polymers
gave 3-O-gluco- and mannopyranosidic (1ꢀ6)-α-D-glucopyranans in moderate yields. These results
are the first reports of the polymerization of 3-O-branched 1, 6-anhydro glucopyranose disaccharide
monomers to give 3-O-branched polysaccharides.
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Keywords:
Ring-opening polymerization
3-O-Branched 1, 6-anhydro glucopyranose
Disaccharide monomer
Trisaccharide monomer
Branched polysaccharides
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1. Introduction
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Ring-opening polymerization of anhydrosugar monomers is a superior method to afford
stereoregular polysaccharides with high molecular weights and define their structures [1]. The
resulting polysaccharides become good biomaterials for investigation of the relationship between the
structure and biological activity, because natural polysaccharides have complex structures, in general,
and it is difficult to know the relationship [2].
Several reports appeared on the ring-opening polymerization of anhydro disaccharide monomers
that were exclusively 4-O-branched 1, 6-anhydro gluco and mannopyranose monomers [3-5]. We
have reported on the synthesis of stereoregular polysaccharides by the ring-opening polymerization
of anhydrosugar monomers [6]. Among them, monosaccharide-branched polysaccharides were also
synthesized by the ring-opening polymerization of several anhydro disaccharide monomers. 1, 6-
Anhydro-2, 3-di-O-benzyl-4-O-(2', 3', 4', 6'-tetra-O-benzyl-β-D-galactopyranosyl)-β-D-
glucopyranose (benzylated 1,6-anhydro lactose (LSHBE)), was synthesized and polymerized by
pentafluoro phosphate (PF ) as a catalyst to give a stereoregular (1ꢀ6)-α-D-lactopyranan with
M
n
5
3
=7.3x10 in good yield after debenzylation [7]. The copolymerization of LSHBE with benzylated 1,
6-anhydro-β-D-glucopyranose (LGTBE) in several feeds gave the corresponding copolysaccharides,
(1ꢀ6)-α-D-glucopyranosidic main chain having different proportions of lactose and glucose units, in
good yields. After sulfation, sulfated (1ꢀ6)-α-
D
-lactopyranans and copoly(lactose and glucose)s
units had potent anti-HIV and blood anticoagulant activities, activities that were found to increase
with a decrease in the proportion of lactose units. Sulfated copolysaccharides with lactose and
glucose units in the proportions of 15 and 85 mol% had the highest biological activities [7]. Recently,
we also reported the synthesis of galactomannans (4-O-galactopyranosidic (1ꢀ6)-α-
D-
mannopyranans) by the ring-opening polymerization of a disaccharide monomer, 1, 6-anhydro-2, 3-
di-O-benzyl-4-O-(2', 3', 4', 6'-tetra-O- benzyl-α-
D
-galactopyranosyl)-β-
D
-mannopyranose
-mannopyranose
(LMGABE) [8]. Copolymerization with 1, 6-anhydro-2, 3, 4-tri-O-benzyl-β-
(LGMBE) was also carried out to give corresponding stereoregular copolysaccharides consisting of a
(1ꢀ6)-α- -mannopyranosidic main chain with various proportions of galactose units. After sulfation,
sulfated synthetic galactomannans had potent anti-HIV and blood anticoagulant activities,
D
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mechanisms that were elucidated by measuring SPR, DLS, and zeta potential with poly-L-lysine as a
model peptide of the HIV surface protein. The sulfated synthetic galactomannans were found to have
strong interactions with poly- -lysine, suggesting that the anti-HIV activity of sulfated synthetic
L
galactomannans is hypothetically due to the interaction of the negatively charged sulfated groups
with the positively charged surface proteins of HIV. Previously, we reported that a new
ribo-disaccharide monomer, 1, 4-anhydro-2-O-benzyl-3-O-(2,3,4,6-tetra-O-benzyl-β-
D-
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galactopyranosyl)-β- -ribopyranose (A2B3GalR), gave a galactose-branched (1ꢀ5)-α-D-
D
ribofuranan with high molecular weights in good yields [9]. The high polymerizability of the 1, 4-
anhydro ribose monomers should originate from a high deformation of the anhydro ribose ring.
Copolymerization with a 1, 4-anhydro-2, 3-di-O-benzyl-α-D-ribopyranose (ADBR) monomer gave
galactopyranose-branched ribofuranans with various proportions of galactopyranose branches. Until
now, all of the 1, 6-anhydro disaccharide monomers were 1, 6- anhydro hexopyranoses with
branches at the 4-O-position without a 1, 4-anhydro ribo disaccharide monomer.
For the synthesis and ring-opening polymerization of an anhydro ribo trisaccharide monomer, 1,
4-anhydro-2-O-benzyl-3-O-(2', 3', 6', 2", 3", 4", 6"-hepta-O-benzyl-β-D-lactosyl)-α-D-ribopyranose
(A2B3LR) synthesized from 1, 4-anhydro ribose and -lactose, was reported and the 1, 4-anhydro
D
ribose trisaccharide monomer (A2B3LR) was expected to have high polymerizability due to a highly
polymerized 1, 4-anhydro ribose unit. We found that the A2B3LR monomer was polymerized by
BF OEt as a catalyst to give lactose-branched (1ꢀ5)-α-D-ribofuranan with high molecular weights
3
2
[10]. This is the first report so far of the ring-opening polymerization of anhydro trisaccharide
monomer.
In this paper, we report for the first time the ring-opening polymerization of 3-O-branched 1, 6-
5
anhydro glucose disaccharide and trisaccharide monomers by PF as a catalyst at -60°C. The
polymerizability of the di- and trisaccharide monomers was elucidated by comparison with those of
4-O-branched di- and trisaccharide monomers on the yields, molecular weights, and the proportion
of disaccharide and trisaccharide units in the main chain of the resulting copolysaccharides.
2. Experimental

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2.1. Materials
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1, 6-Anhydro-2, 4-di-O-benzyl-β-
benzylation of 1, 6-anhydro-β- -glucopyranose (LG) with benzyl bromide by using anhydrous
barium hydroxide according to the method of our previous paper [11]. 2, 3, 4, 6-Tetra-O-acetyl-1-O-
trichloroacetimidoyl-α- -glucopyranose 3, -mannopyranose 4, and -maltopyranose 5 were prepared
D-glucopyranose (LGDBE 2) was synthesized by selective
D
D
by trichloroacetimidation of 2, 3, 4, 6-tetra-O-acetyl-α-D-glucopyranoside, -mannopyranoside, and
-maltopyranoside with, respectively, trichloroacetonitrile in 67.0%, 58.2%, and 68.4% yields,
respectively, according to the methods described in the literature [12]. A Diaion SK 1B ion exchange
resin was used for the neutralization after alkaline deacetylation.
2.2 Synthesis of 3-O-branched 1, 6-anhydro glucopyranose monomers
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2, 3, 4, 6-Tetra-O-acetyl-1-O-trichloroacetimidoyl-α-
D
-glucopyranose (2.7g, 5.45 mmol) and 1,
Cl (16 mL)
6-anhydro-2, 4-di-O-benzyl-β- -glucopyranose (LGDBE 2) were dissolved in dry CH
D
2
2
3 2
in the presence of molecular sieves (4A, 1.2g). Boron trifluoride etherate (BF OEt ) (1.1 mmol) was
added dropwise to the mixture at -60°C. After the mixture was stirred for 20 min, the molecular
sieves were removed by filtration and then chloroform (50 mL) was added to the clear filtrate. The
filtrate was washed several times with 5% aqueous sodium hydrogen carbonate solution and water,
and then dried over anhydrous sodium sulfate. After evaporation, the residue was purified by silica
gel column chromatography with a hexane-ethyl acetate (2:1 vol) mixed solvent to give 1, 6-
anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-acetyl-α-D-glucopyranosyl)-β-D-glucopyranose
(1.34 g) in 49.0% yield.
For deacetylation, 1, 6-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-acetyl-α-
D-
glucopyranosyl)-β- -glucopyranose (1.34 g) in methanol (10 mL) was stirred with sodium
D
methoxide (40.2 mg, 0.75 mmol) at room temperature. After 4 h, to the mixture was added an ion
+
exchange resin (H ) to neutralize the solution. After filtration of the ion exchange resin, the filtrate
was evaporated to give 1, 6-anhydro-2, 4-di-O-benzyl-3-O-(α-
(0.9 g, 1.8 mmol) in 91.4% yield, which was directly used for the next reaction. 1, 6-Anhydro-2, 4-
di-O-benzyl-3-O- (α- -glucopyranosyl)-β- -glucopyranose (0.9 g, 1.8 mmol) in dry DMF (5 mL)
D-glucopyranosyl)-β-D-glucopyranose
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solution was added dropwise to dry DMF (15 mL) solution with NaH (0.36 g, 15 mmol) and the
mixture was stirred for 0.5 h at room temperature. Benzyl bromide (1.64 mL, 14.4 mmol) was added
dropwise to the mixture. After stirring for 3 h at 0°C, the mixture was evaporated to give 1,
6-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-D-glucopyranosyl)-β-D-
glucopyranose (LGG 7) (1.30 g) in 84.2% yield after silica gel column chromatography with a
hexane-ethyl acetate (3:1 vol) mixed solvent. The specific rotation and elementary analysis were
2
5
[α]
=+16.4° (c1, CHCl ) and found: C, 74.89%; H, 6.43% (calcd for C54H O10: C, 74.98%; H,
3 56
D
6.52%).
Other disaccharide and trisaccharide monomers, 1, 6-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-
tetra-O-benzyl-α- -mannopyranosyl)- (LGM 6) and -3-O-(2', 3', 6', 2", 3", 4", 6"-hepta-O-benzyl-
D
α-D
-maltopyranosyl)-β-D-glucopyranoses (LGMAL 8) were prepared by the same method as above
from 1, 6- anhydro-2, 4-di-O-benzyl-β-
D
-glucopyranose 2 and 2, 3, 4, 6-tetra-O-acetyl-1-O-
trichloroacetimidoyl-α-D-mannnopyranose 3 and 4-O-(2', 3', 4', 6'-tetra-O-acetyl-1-O-
trichloroacetimidoyl-α-D-glucopyranose 5, respectively, in 44.0% and 35.7% yields from 2. The
specific rotation at 25°C and elemental analysis were [α] D2 5=+27.6° (c1, CHCl
74.88%; H, 6.47% (calcd for C54
10: C, 74.98%; H, 6.52%) for LGM 6, and [α]
CHCl ) and found: C, 74.86%; H, 6.47% (calcd for C81 15: C, 74.98%; H, 6.52%) for LGMAL 8,
respectively.
3
) and found: C,
2
5
H
56
O
D
=+52.3° (c1,
3
84
H O
2.3. Ring-opening polymerization and copolymerization of 3-O-branched 1, 6-anhydro
glucopyranose monomers
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A typical procedure for the ring-opening copolymerization of the disaccharides and trisaccharide
monomers is as follows (No. 3 in Table 1). The polymerization was carried out under high vacuum
-5
condition below 10 mmHg at -60°C. The disaccharide monomer (LGG 7) (0.13 g) and LGTBE
(0.07 g) were measured in a glass polymerization ampoule and then dry CH Cl (0.4 mL) was added
under pressure reduced below 10 mmHg to dissolve the monomers. After the polymerization
ampoule had been cooled in a liquid N Dewar vessel, PF (20 mol% to the monomers) was
transferred to the polymerization ampoule at the same temperature. The polymerization ampoule was
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maintained with gentle stirring for 24 h at -60°C and then the polymerization was terminated by
addition of a small amount of MeOH to produce a white precipitate of the corresponding copolymer.
3
The copolymer was purified by reprecipitation using CHCl -MeOH mixed solvent several times to
remove unpolymerized monomers and then freeze-dried from benzene to give the copolymer as a
3
white precipitate in 29.5% yield. The copolymer had the molecular weight of M
n
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specific rotation of [α]
3
= +74.1° (c1, CHCl ). The proportion of the disaccharide unit was 15.3
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mol% according to the C NMR measurement. Other polymerization and copolymerization were
performed by the same procedures as above. The results are shown in Tables 1 and 2.
2.4. Debenzylation of benzylated 3-O-branched polymers
3
Copoly((LGG and LGTBE) (0.30 g) with M
mol% dissolved in 3 mL of dry CH Cl
(50 mL) at -78°C, and the mixture was stirred for 1 h at -78°C under N
of small amounts of NH Cl and MeOH, liquid NH was evaporated at room temperature. The residue
=4.2x10 and the proportion of LGG 7 unit of 10.0
n
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2
was added dropwise to a solution of Na (0.5 g) in liquid NH
3
2
atmosphere. After addition
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3
was washed with ethyl ether and then dissolved in water (30 mL). The aqueous solution was
dialyzed with water for 2 d. After filtration, the filtered water was concentrated to 10 mL and then
freeze-dried to give 3-O-α-
molecular weight was M
3-O-α-
D
-glucopyranosyl (1ꢀ6)-α-D-glucopyranan (0.05 g) in 40.6% yield. The
3
n
=4.4x10 and the proportion of LGG 7 unit was 7.8 mol%.
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00
D
-Mannopyranosyl (1ꢀ6)-α-
D
-glucopyranan (0.05 g) was also obtained from
copoly(LGM and LGTBE) (0.16 g) by the same method as described above. The results are shown in
Table 3.
2.5. Measurements
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Elemental analysis of monomers was performed by a CE-440 elemental analyzer and a Mettler
TOLEDO XS3DU electronic microbalance. Specific rotations were measured on a JASCO DIP-140
digital polarimeter with a 1 dm cell in chloroform or water at 25°C and a concentration of 1 mg/mL.
FT-IR spectra were recorded on a Perkin Elmer Spectrum One FT-IR spectrometer by a KBr pellet
1
13
method. H and C NMR spectra were obtained by a JEOL JMN AEC-600 spectrometer at 25°C or

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3 6 2
40°C in CDCl , DMSO-d , or D O solvent with tetramethylsilane as an internal standard. The
monomers were purified by an organic phase HPLC system with an RI-8020 detector using a
TSK-gel column (Silica-60, 21.5 mmx300 mm) eluted with hexane-ethyl acetate mixed solvent at
40°C. Molecular weights of copolymers or copolysaccharides were estimated by an organic or
aqueous phase GPC system using organic phase TSK-gel columns (G2500PWXL, G4000PWXL, and
G5000PWXL, 7.6 mmx300 mmx3) eluted with chloroform or aqueous phase columns (G2500HXL
,
G4000HXL, and G5000HXL 7.6 mmx300 mmx3) eluted with 66.7 mmol of phosphate buffer at
pH=6.68) at 40°C. Polystyrene (Shodex standard SM-105) or dextran (Shodex standard P-82) was
used as a molecular weight reference.
3. Results and Discussion
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3.1. Synthesis of new 3-O-branched 1, 6-anhydro glucopyranose disaccharide and trisaccharide
monomers
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The ring-opening polymerization of 4-O-branched 1, 6-anhydro disaccharide monomers has
been reported to give branched polysaccharides with stereoregular (1ꢀ6)-α main chain having a
monosaccharide branch in each sugar unit. So far, all of the 1, 6-anhydro disaccharide monomers
without 1, 4-anhydro ribopyranose monomers were 4-O-branched 1, 6-anhdro gluco and
mannopyranoses, monomers that should have lower steric hindrance at the 4-O position in 1, 6-
anhydro glucopyranose for the ring-opening polymerization than that of the 3-O-branched 1, 6-
anhydro hexopyranose monomers due to the distance between the C1 and C4 positions. In this work,
new 3-O-branched 1, 6-anhydro glucopyranose monomers were synthesized for the first time and the
polymerizability was compared with that of the 4-O-branched hexopyranose monomers previously
reported.
Scheme 1 shows the synthesis and ring-opening polymerization of 3-O-branched 1, 6-anhydro
Scheme 1
glucopyranose monomers. 1, 6-Anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-
mannopyranosyl)-β- -glucopyranose (LGM 6) was prepared by the glycosylation of the 3-O
position of 1, 6-anhydro-2, 4-di-O-benzyl-β- -glucopyranose 2 with 2, 3, 4, 6-tetra-O-acetyl-1-O-
D-
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trichloroacetimidoyl-α-
D
-mannopyranose 3, a viscous liquid, in 44.0% yield after deacetylation and
subsequent benzylation. In the same manner, other 3-O-branched disaccharide and trisaccharide
monomers, 1, 6- anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α- -glucopyranosyl)-
D
β-
D
-glucopyranose (LGG 7) and 1, 6-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 6', 2", 3", 4", 6"-
-maltosyl)-β- -glucopyranose (LGMAL 8), were synthesized by the
hepta-O-benzyl-α-
D
D
glycosylation of 2 with the glucose 4 and maltose imidates 5, respectively, in 41.3% and 35.7%
yields. Before polymerization, the 3-O-branched disaccharide and trisaccharide monomers were
highly purified by using HPLC. The elemental analysis of the monomers was in good agreement
with the calculated ones. The monomers with low purity were not polymerized.
13
Figure 1 shows the C NMR spectra of the monomers. All carbon signals were assigned by the
Figure 1
combination of H-H COSY and HMQC 2D NMR measurements. The C1 signals due to 1, 6-anhydro
glucopyranose appeared between 100 and 102 ppm, respectively. The C1' signal of the 3-O-branched
mannose, glucose, and maltose were absorbed at 98.0 ppm (Figure 1A), 103.5 ppm (Figure 1B), and
103.3 ppm (Figure 1C), respectively. The C1' signal due to the branched mannose in Figure 1A
appeared at the relatively higher magnetic field of 98.0 ppm than that of the branched glucose in
Figures 1B and 1C. On the trisaccharide monomer in Figure 1C, the C1" signal due to the terminal
glucose moiety was found to appear at the higher magnetic field of 96.5 ppm. The specific rotation
2
5
of the monomers at 25°C showed positive and moderate values, [α]
=+27.6°, +16.4°, and +52.3°
D
(c1, CHCl ), moderate and positive values that were attributed to the β-configuration of the 1,
3
6-anhydro glucopyranose and α-configuration of the branched glucose, mannose, and maltose
moieties. The specific rotation of the monosaccharide monomer, 1, 6-anhydro-2, 3, 4-tri-O-benzyl-
2
5
β-D
-glucopyranose (LGTBE), was a large negative value, [α]
=-30.8° (c2.7, CHCl ) due to the
3
D
β-configuration [13].
3.2. Ring-opening polymerization of 3-O-branched 1, 6-anhydro glucopyranose monomers
2
2
60
61
These 3-O-branched monomers were highly purified by using a preparative HPLC and then
5
polymerized by PF as a catalyst under high vacuum condition for 24 h at -60°C. A relatively higher

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quantity of PF
5
catalyst (20 mol% to the feeds) was used with reference to previous results [7].
Table 1 shows the results for the polymerization of the 3-O-branched disaccharide monomer,
Table 1
1, 6-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-D-glucopyranosyl)-β-D-
glucopyranose (LGG 7). It was found that the monomer was polymerized to give the corresponding
polymer, but the yield was low. Therefore, copolymerization with the LGTBE monomer was
performed in several monomer feeds. The copolymerization of LGG 7 with LGTBE in the monomer
feeds of 25:75, 50:50, and 75:25 mol% gave the corresponding copolymers in low to moderate yields,
29.5-64.8% yields, respectively, and the yields increased with increasing proportions of LGTBE
monomer as shown in Nos. 2-4 in Table 1. In No. 3, although the copolymerization of LGG 7 with
LGTBE in the feed of 50:50 mol% afforded the corresponding polymer in 29.5% yield, and
proportion of the LGG 7 unit in the copolymer was 15.3 mol%, which was the highest proportion in
the copolymerization of the LGG 7 and LGTBE monomers. These copolymerization results suggest
that the 3-O-branched 1, 6- anhydro glucopyranose disaccharide monomer gave the corresponding
copolymers. However, the disaccharide monomers had lower polymerizability than the
4-O-branched disaccharide monomers.
The 3-O-Mannopyranosyl 1, 6-anhydro glucopyranose monomer (LGM 6) was also
copolymerized with LGTBE by the same polymerization conditions as LGG 7. The results are
represented in Table 2. The LMG monomer also had low polymerizability (No. 4 in Table
Table 2
2). As shown in No. 2, the copolymerization of LGM 6 with LGTBE in the feed of 50:50 mol% was
found to give the corresponding polymer in 52.4% yield. The molecular weight was relatively high,
3
M
n
=49.7x10 , and the proportion of the LGM 6 disaccharide unit in the copolymer was 16.1 mol%.
Both disaccharide monomers LGG 7 and LGM 6 in the feed of 50 mol% gave the highest proportion
of the disaccharide unit in the copolymer. The reason why the higher proportion was exclusively
obtained when the disaccharide unit was used in 50 mol% feed is under consideration. The yield of
the copoly((LGM and LGTBE) increased with increasing feed of the LGTBE monomer having high
ring-opening polymerizability [14], and the proportion of the disaccharide unit in the copolymers was
lower than that of the feed.

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We reported previously that the 4-O-branched 1, 6-anhydro hexopyranose monomers,
benzylated 1, 6-anhydro-β-D-lactopyranose and benzylated 4-O-galactopyranosyl 1, 6-anhydro
mannopyranose, had high polymerizability to give the corresponding homopolymers in 68.5% and
46.7% yields, respectively [7, 8].The copolymerization with LGTBE gave the corresponding
copolymers in 78.0% and 93.5% yields, respectively. The proportion of the disaccharide units in the
copolymers was almost the same as that in the feeds. Therefore, we believe the 4-O-branched 1, 6-
anhydro hexopyranose monomers had higher polymerizability than the 3-O-branched 1, 6-anhydro
hexopyranose monomers. The low polymerizability of the 3-O-branched 1, 6-anhydro
glucopyranose monomers was affected by the steric hindrance of the bulky 3-O-branched sugar
moiety compared with that of the 4-O-branched disaccharide monomers. In addition, the distance
between a C-C single bond is 0.154 nm [15, 16] and the distance between the C1 and C3 positions in
the 1, 6-anhydro glucopyranose (0.308 nm) was shorter than that between the C1 and C4 positions
(0.462 nm). Therefore, the steric hindrance of the sugar branch at the C3 position was relatively
higher than that of the C4 position.
The 3-O-branched trisaccharide monomer LGMAL 8 showed no polymerizability under any
polymerization conditions, probably because of the steric hindrance of the bulky 3-O-maltopyranosyl
branch and lowering of polymerizability due to the increasing molecular weight. In general, anhydro
trisaccharide monomers decrease the ring-opening polymerizability because of increasing the steric
hindrance, molecular weight, and stability of the anhydro ring. We reported previously that a ribo
trisaccharide monomer, 1, 4-anhydro-2-O-benzyl-3-O-(2', 3', 6', 2", 3", 4", 6"-hepta-O-benzyl-β-
D-
lactopyranosyl)-α- -ribopyranose, had relatively high polymerizability to give the corresponding
D
ribofuranans with a lactose branch in every ribofuranose unit in 45-62% yields. The polymerizability
of the 3-O-lactopyranosyl ribo trisaccharide monomer may be attributed to the high ring-opening
polymerizability of the 1, 4-anhydro ring in ribopyranose moiety. The ring-opening polymerizability
of the 1, 4-anhydro ribopyranose ring should be higher than that of the 1, 6-anhydro glucopyranose
ring [17].
13
Figure 2 shows the C NMR spectra of the copolymers (A)-(C) consisting of LGG and LGTBE
Figure 2
units in the proportion of (A) 8.4:91.6 mol%, (B) 15.3:84.7 mol%, and (C) 0.4:99.6 mol%,

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35
respectively, and (D) the homopolymer, 2, 4, 6-tri-O-benzyl-(1ꢀ6)-α-D-glucopyranan. All signals
were assigned by the combination of H-H COSY and HMQC measurements. In Figure 2B, the
carbon signals due to the LGTBE unit appeared as large intense signals. The C1 and C6 signals due
to 3-O-branched glucopyranose units were absorbed as small signals at 97.0 ppm and 69.2 ppm for
13
the C1 and C6', and 102.8 ppm and 65.8 ppm for the C1" and C6" signals, respectively. The C
NMR spectra of copoly((LGM and LGTBE) are presented in Figure 3, in which the C1" and C1'
Figure 3
signals due to the LGM unit consisting of mannose and glucose appeared at 99.2 ppm and 97.5 ppm
as overlapped signal of the C1 signal due to the LGTBE unit, respectively. Taking into account
higher and positive specific rotations, copoly((LGG and LGTBE)s and copoly((LGM and LGTBE)s
had a (1ꢀ6)-α-D-glucopyranosidic main chain with α-D-glucopyranose and α-D-mannopyranose
branches at the C3 position in the main chain, respectively. From the NMR spectra, it was found that
both disaccharide monomers were copolymerized with LGTBE to give the corresponding
(1ꢀ6)-α-D-glucopyranosidic stereoregular copolymers.
3.3. Debenzylation to 3-O-gluco and mannopyranosyl glucopyranans
3
3
3
3
3
3
3
3
3
3
3
3
36
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47
The copolymers were debenzylated with Na in liquid ammonia at -78°C to give free
copolysaccharides after dialysis with water and then freeze-drying. The dialyzed membrane with a
molecular weight elimination limit of 3500 Da in water was used because the molecular weight of
the copolymers was low. Table 3 shows the results of debenzylation of copoly((LGG and LGTBE)
Table 3
3
25
with M
n
=4.2x10 , [α]D =+78.1° (c1, CHCl
3
), with the proportion of LGG unit of 10.0 mol%, and
3
25
D
copoly((LGM) 6 and LGTBE) with M
n
=15.5x10 , [α]
3
=+74.2° (c1, CHCl ), with the proportion of
LGM 6 unit of 10.3 mol%, respectively. For copoly((LGG and LGTBE), the debenzylated
3
copolysaccharide with M
n
=4.4x10 was obtained in 40.6% yield. The proportion of the disaccharide
unit in the copolysaccharide was 7.8 mol%. Copoly((LGM and LGTBE) gave the corresponding
3
copolysaccharide with M
n
=6.1x10 in 50.5% yield. The disaccharide unit was 7.1 mol% in the
copolysaccharide. The specific rotation of both copolysaccharides increased to high positive values,

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+132.3° and +134.2° from +78.1° and +74.2° before debenzylation, respectively, suggesting that the
copolysaccharides had (1ꢀ6)-α glucopyranosidic stereoregularity in the main chain with
α-D-glucopyranose and α-D-mannopyranose branches.
13
Figure 4 shows the C NMR spectra of (A) 3-O-glucopyranosyl and (B) 3-O-mannopyranosyl
Figure 4
(1ꢀ6)-α-
D
D
-glucopyranans with the branched sugar proportions of 7.8 mol% and 7.1 mol%, and (C)
-glucopyranan, respectively. After debenzylation, the signals due to benzyl groups
(1ꢀ6)-α-
disappeared. It was found that the C1 signals due to main chain glucopyranose without 3-O-branched
sugar units appeared at 100.5 ppm as sharp and single signals, indicating that the copolysaccharides
had highly (1ꢀ6)-α-D-glucopyranosidic stereoregularity. The C1' signals due to the main chain
glucopyranose unit with 3-O-gluco and mannopyranose branches appeared as overlapped signals at
100.5 ppm, respectively, and the C1" signals of the 3-O-branched gluco and mannopyranose were
absorbed at 105.6 ppm and 104.0 ppm as small and singlet signals, respectively. The C6" signals
appeared around 63.5 ppm as several small absorptions, respectively, probably due to the effect of
the random copolymerization of the disaccharide and LGTBE units. The FT-IR spectra before and
after debenzylation of copoly((LGG and LGTBE) are shown in Figure 5. Before debenzylation in
Figure 5A, several small and large intense signals due to benzyl groups appeared between 1700-2000
Figure 5
-1
-1
-1
cm , around 1500 cm , and at 750 cm . After debenzylation to recover hydroxyl groups in Figure
-1
5B, a large absorption due to hydroxyl groups appeared at 3400 cm and the signals due to benzyl
-1
groups disappeared. In addition the medium absorption at 1650 cm due to a bending vibration of
water appeared.
4. Conclusion
3
3
3
3
72
73
74
75
Two new 3-O-branched 1, 6-anhdro glucopyranose disaccharide monomers, 1, 6-anhydro-2,
4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-
-glucopyranosyl)-β- -glucopyranose (LGG 7), and a trisaccharide monomer, 1, 6-anhydro-2, 4-
di-O-benzyl-3- O-α-(2', 3', 6', 2", 3", 4", 6"-hepta-O-benzyl-α- -maltosyl)-β- -glucopyranose
D-mannopyranosyl)- (LGM 6) and
D
D
D

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(LGMAL 8), were synthesized and the ring-opening polymerizability and copolymerizability with 1,
6-anhydro-2, 3, 4- tri-O-benzyl-β-D-glucopyranose (LGTBE) were examined for the first time by
using PF as a catalyst at -60°C. Unfortunately, the 1, 6-anhydro trisaccharide monomer LGMAL 8
5
showed no homopolymerizability and copolymerizability with LGTBE. Although the
homopolymerizability of the disaccharide monomers was low, the copolymerizations with LGTBE
were found to give the corresponding copolysaccharides, 3-O-glucopyranosyl and -mannopyranosyl
(1ꢀ6)-α-D- glucopyranans, respectively, after deprotection to recover hydroxyl groups. The
polymerization yields of the 3-O-branched disaccharide monomers were not very high, 12.8-68.5%,
3
but the monomer feeds of 50:50 mol% gave higher molecular weights of M
n
=8.4x10 for
3
copoly((LGG and LGTBE) and M
n
=49.7x10 for copoly((LGM and LGTBE), respectively, The
proportions of the disaccharide monomer units in the corresponding copolymers were 15.3 mol%
and 16.1 mol%, respectively. The polymerizability of the 3-O-branched disaccharide monomers was
relatively lower than that of the 4-O-branched disaccharide monomers we reported previously,
probably due to the steric hindrance of the bulky 3-O-branched sugar moieties. The distance between
the C1 and C3 positions in 1, 6-anhydro glucopyranose was shorter than that between the C1 and C4
positions. This is the first report on the ring-opening polymerization of 3-O-branched disaccharide
monomers.
Acknowledgments
This research was partly supported by a Grant-in-Aid for Scientific Research (C) from Japan
Society for the Promotion of Science 2012-2014 (No. 24550129) and 2015-2017 (No. 15K05617).
Conflict of interest
The authors have no conflict of interest to disclose with respect to this article.
4
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References
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[1] C. Schuerch, Synthesis and polymerization of anhydro sugars. In Advances in carbohydrate
chemistry and biochemistry, Tip-son, R. S., Horton, D., Eds; Academic Press, Inc: New York, 1981;
pp. 157-212.
[2] T. Yoshida, Synthetic and Natural Polysaccharides Having Specific Biological activities. In

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Polysaccharides, Structural diversity and functional versatility, 2nd ed; Dumitriu S. Ed; Marcel
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[4] B. Veruovice, C. Schuerch, The preparation of comb-shaped polysaccharides by polymerization
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[5] K. Kobayashi, K. Nomura, M. Okada, Chemical synthesis of a comb-shaped branched
stereoregular polysaccharide, 4-O-β-D-mannopyranosyl-(1ꢀ6)-β-D-mannopyranan. Carbohydr. Res.
242 (1993) 161-166.
[6] T. Yoshida, Synthesis of polysaccharides having specific biological activities.
Prog. Polym. Sci. 26 (2001) 379-441.
[7] S. Han, Y. Kanematsu, K. Hattori, H. Nakashima, T. Yoshida, Ring-opening polymerization of
benzylated 1, 6-anhydro-β-D-lactose and specific biological activities of sulfated
(1ꢀ6)-β- -lactopyranans. J. Polym. Sci., Part A: Polym. Chem. 47 (2009) 913-924.
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[8] D. Budragchaa, S. Bai, T. Kanamoto, H. Nakashima, S. Han, T. Yoshida, Synthetic
galactomannans with potent anti-HIV activity. Carbohydr. Poly. 130 (2015) 233-242.
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[9] T. Yoshida, K. Endo, Synthesis of branched ribo-polysaccharides with defined structures by
ring-opening polymerization of 1, 4-anhydro ribo-disaccharide monomers.
Macromol. Biosci. 1 (2001) 298-304.
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[10] D. Yoshida, S. Han, K. Narita, K. Hattori, T. Yoshida, Synthesis of oligosaccharide-branched
ribofuranan by ring-opening polymerization of a new anhydro ribo trisaccharide monomer.
Macromol. Biosci. 9 (2009) 687-693.
[11] T. Iversen, D.R. Bundle, Synthesis of the colitose determinant of Escherichia coli 0111 and 3,
6-di-O-(α-D-galactopyranosyl)-α-D-glucopyranoside. Can. J. Chem. 60 (1982) 299-303.
[12] M. Polakova, M. U. Roslund, F. S. Ekholm, T. Saloranta, R. Leino, Synthesis of
β-(1ꢀ2)-linked Oligomannosides. Eur. J. Org. Chem. 6 (2009) 870-888
[13] E. R. Ruckel, C. Schuerch, Preparation of high polymers from 1, 6-anhydro-2, 3,
4-tri-O-substituted β-D-glucopyranose. J. Org. Chem. 31(1966) 2233-2239.
[14] T. Uryu, C. Schuerch, Preparation of high molecular weight 2, 3,
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(1971) 342-345.
[15] F. F. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen, Tables of bond lengths
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[17] T. Uryu, K. Kitano, K. Ito, J. Yamanouchi, K. Matsuzaki, Selective ring-opening
polymerization of 1, 4-anhydro-α-D-ribopyranose derivative and synthesis of stereoregular
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(1ꢀ6)-β- -ribopyranan. Macromol. 14 (1981) 1-9.
D
Legend to Scheme and Figures
Scheme 1 Synthesis and ring-opening polymerization of 3-O-branched 1, 6-anhydro glucose
monomers 6, 7, and 8. The polymerization was carried out with PF
-60
under high vacuum condition.
5
as a catalyst at
13
Figure 1 150 MHz C NMR Spectra of 3-O-branched monomers. (A) 1, 6-Anhydro-2, 4-di-
O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α- -mannopyranosyl)-β- -glucopyranose
(LGM), (B) 1, 6-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-
glucopyranosyl)-β- -glucopyranose (LGG), and (C) 1, 6-anhydro-2, 4-di-O-benzyl-
3-O-(2', 3', 4', 6'-tetra-O-benzyl-α- -maltosyl)-β- -glucopyranose (LGMAL) in
CDCl at 25°C. The specific rotation at 25°C was (A) [α]
4
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97
98
D
D
D
-
D
D
D
2
5
3
D
=+27.6°, (B) +16.4°, (C)
3
), respectively. All signals were assigned by H-H COSY and
+52.3° (c1, CHCl
HMQC spectra.
13
Figure 2 150 MHz C NMR Spectra of (A)-(C) copoly(LGG and LGTBE)s and (D)
poly(LGTBE) in CDCl at 25°C. The proportions of the disaccharide unit in the
copolymers were (A) 8.4 mol%, (B) 15.3 mol%, and (C) 0.4 mol%, respectively.
3
2
5
The specific rotation at 25°C was (A) [α]D =+66.0°, (B) +74.1°, (C) +75.9°, and
(D) +60.6°, and (D) +114.1° (c1, CHCl ), respectively. Signals were assigned by
3
H-H COSY and HMQC spectra.
13
Figure 3 150 MHz C NMR Spectra of copoly(LGM and LGTBE)s in CDCl
3
at 25°C.
The proportions of disaccharide unit were (A) 16.1 mol% and (B) 1.7 mol%,
respectively. The specific rotation at 25°C was (A) [α]
(c1, CHCl3).
2
5
D
=+97.4° and (B) +86.8°
13
Figure 4 150 MHz C NMR Spectra of debenzylated polymers. (A) Copoly(LGG and
LGTBE), (B) copoly(LGM and LGTBE), and (C) poly(LGTBE) in D O at 40°C.
= +132.3°, (B) +134.2°, and (C)
2
2
5
The specific rotations were at 25°C was (A) [α]
D
+129.6°, respectively. The proportions of disaccharide units were (A) 7.8 mol% and
(B) 7.1 mol%, respectively. Signals were assigned by H-H COSY and HMQC
spectra.
Figure 5 FT-IR spectra (A) before and (B) after debenzylation of copoly(LGG and LGTBE)
measured by a KBr method. The proportions of disaccharide units were (A) 10.0
2
5
mol% and (B) 7.8 mol%, respectively. The specific rotation at 25°C was (A) [α]
=+78.1° (c1, CHCl ) and (B) +132.3° (c1, H O), respectively.
D
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Table 1
Ring-opening polymerization and copolymerization of 1, 6-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4',
6
'-tetra-O-benzyl-α-
D
-glucopyranosyl)-β-
D
-glucopyranose (LGG) with 1, 6-anhydro-2, 3, 4-tri-O-
a
benzyl-β-
D
-glucopyranose (LGTBE)
Monomer
Polymer
b
c
2
5
No
LGG
LGTBE
Yield
[α]
D
M
n
LGG
3
g
mol%
g
mol%
%
deg
x10
unit in d
polymer
mol%
1
2
3
4
5
0
0.20
0.12
0.07
0.03
0
100
75
50
25
0
79.5
64.8
29.5
29.6
12.8
+114.1
+75.9
+74.1
+66.0
+50.0
13.1
2.6
8.4
4.8
1.8
0
0.08
0.13
0.17
0.20
25
50
75
0.4
15.3
8.4
e
100
-
a Total monomer weight: 0.2 g, Solvent: CH Cl ; 0.4 ml, Catalyst: PF ; 20 mol% to feed, Temperature: -60°C,
2
2
5
Polymerization time: 24 h.
b Measured in CHCl (c1) at 25°C..
3
c Determined by chloroform GPC.
1
3
d Calculated from C NMR spectrum.
e The proportion could not be measured due to low yield of the polymer.

ACCEPTED MANUSCRIPT
Table 2
Ring-opening polymerization and copolymerization of 1, 6-anhydro-2, 4-di-O-benzyl-3-
O-(2', 3', 4', 6'-tetra-O-benzyl-α- -mannopyranosyl)-β- -glucopyranose (LGM) with
, 6-anhydro-2, 3, 4-tri-O-benzyl-β- -glucopyranose (LGTBE)
D
D
a
1
D
Monomer
LGTBE
Polymer
25
b
c
[
α]
D
No
LGM
Yield
%
M
n
LGM
3
g
mol%
g
mol%
deg
x10
unit in
polymer
mol%
d
1
2
3
4
0.08 25
0.13 50
0.17 75
0.20 100
0.12 75
0.07 50
0.03 25
68.5
52.4
51.4
25.5
+86.8
+97.4
+60.1
+36.7
5.7
49.7
4.2
1.71
16.1
-
0
0
1.8
100
a Total monomer weight: 0.2 g, Solvent: CH
Temperature: -60°C, polymerization time: 24h.
b Measured in CHCl (c1) at 25°C..
c Determined by chloroform GPC.
2 2 5
Cl ; 0.4 ml, Catalyst: PF ; 20 mol% to feed,
3
1
3
d Calculated from C NMR spectrum.

ACCEPTED MANUSCRIPT
a
Table 3 Debenzylation of copoly(LGG and LGTBE) and copoly(LGM and LGTBE)
b
Benzylated copolymer
Free copolysaccharide
e
g
d
f
c
25
25
No
Proportion
M
[α]
D
Yield
%
M
Disaccharide unit [α]
D
n
n
c
LGG LGM LGTBE
mol%
in main chain
3
3
g
x10
deg
g
x10
mol%
deg
1
2
0.30 10.0
0.16
-
90.0
89.7
4.2
+78.1
+74.2
0.05
0.03
40.6
50.5
4.4
6.1
7.8
7.1
+132.3
+134.2
-
10.3
15.5
3
a Condition: Na; 0.5 g, Solvent: Liq. NH ; 50 mL, Temperature: -78°C, Time: 60 min.
b LGG: 1, 6-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-D-glucopyranosyl)-β-D-glucopyranose,
LGM: 1, 6-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-D-mannopyranosyl)-β-D-glucopyranose,
LGTBE: 1, 6-anhydro-2, 3, 4-tri-O-benzyl-β-D-glucopyranose.
13
c Calculated from the intensity of the C1 signal of the C NMR spectrum (mol%).
d Determined by chloroform GPC.
e Measured in CDCl
f Determined by aqueous GPC.
g Measured in H O (c1) at 25°C.
3
(c1) at 25°C.
2

ACCEPTED MANUSCRIPT
-
CH Ph
2
6
'
CH OBn
2
6
A
B
C
O
O
5
'
O
BnO
OBn
1'
O
4
5
4
'
1
5'
3
4
'
BnO
BnO
2
3'
2'
3
2
1
OBn
5
1'
LGM
2'
6'
6
3'
4
6
'
CH OBn
2
6
O
O
5
'
O
-CH Ph
2
1
'
4
5
4
' OBn
O
1
2'
5
2
'
5
BnO
BnO
2
1
'
3'
1
OBn
3
2
'
4'
OBn 3'
3
4
6
LGG
6'
6
'
6
CH OBn
2
O
6
"
O
OBn
4
5
4'
O
5
'
1'
O
CH OBn
2
1
5
"
O
O
2'
2
BnO
OBn
3'
4
" OBn
3
OBn
-CH Ph
2
1"
BnO
2"
OBn
5
3
3
"
5", 5' 4'
4"
LGMAL
1
2'
1
'
2
1
"
3'
2"
3
"
4
6
6'
6
"
PPM
110
100
90
80
70
60
13
Figure 1. 150 MHz C NMR Spectra of 3-O-branched monomers.
A) 1, 6-Anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-D-
mannopyranosyl)-β-D-glucopyranose (LGM), (B) 1, 6-anhydro-2, 4-di-O-benzyl-3-O-
2', 3', 4', 6'-tetra-O-benzyl-α-D-glucopyranosyl)-β-D-glucopyranose (LGG), and (C) 1,
-anhydro-2, 4-di-O-benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-D-maltosyl)-β-D-
glucopyranose (LGMAL) in CDCl at 25 C.
(
(
6
3
2
5
The specific rotation at 25 C was (A) [α]
=+27.6 , (B) +16.4 , (C) +52.3 (c1,CHCl3),
D
respectively. All signals were assigned by H-H COSY and HMQC spectra.
Figure 1

ACCEPTED MANUSCRIPT
A
B
x
6
"
6
'
CH OBn
6
2
(
OCH2
-CH Ph
5
"
(OCH
2
O
2
1
O
"
4'
O
5'
1'
5
4
"
OBn
O
4
n
1
)
3
' 2' )
OBn
4"
2"
OBn
2"
2
BnO
2
BnO
3
"
m
BnO
4'
4
5"
BnO
3
3
OBn
1
5'
5
6
1"
3"
2'
3'
6'
1'
6"
C
D
-
CH Ph
2
6
(
OCH
2
5
O
1
)
4
OBn
2
1
3
m
2
OBn
4
5
BnO
3
6
PPM
110
100
90
80
70
60
13
Figure 2. 150 MHz C NMR Spectra of (A)-(C) copoly(LGG and LGTBE)s and (D)
poly(LGTBE) in CDCl at 25 C. The proportions of disaccharide units in the
3
copolymers were (A) 8.4 mol%, (B) 15.3 mol%, and (C) 0.4 mol%, respectively. The
2
5
specific rotation at 25 C was (A) [α]
=+66.0 , (B) +74.1 , (C) +75.9 , and (D) +114.1
D
(
c1, CHCl ), respectively. Signals were assigned by H-H COSY and HMQC spectra.
3
Figure 2

ACCEPTED MANUSCRIPT
6
"
CDCl3
6
'
CH OBn
A
2
(OCH
6
2
5
"
OBn
(OCH
-CH Ph
2
O
2
1" 4'
O
O
5
4
"
5'
1'
BnO
O
4
1
)
2
' )
OBn
BnO
n
3
"
2" BnO
m
3'
BnO
2
BnO
3
OBn
3
2
4
1
"
2
"
5
5
"
6
2
'
4"
3
"
1
6
"
1
'
6
'
B
3
2
1
4
5
6
1
"
1
'
x
PPM
110
100
90
80
70
60
13
Figure 3. 150 MHz C NMR Spectra of copoly(LGM and LGTBE)s in CDCl at 25 C.
3
The proportions of the disaccharide units were (A) 16.1 mol% and (B) 1.7 mol%,
2
5
respectively. The specific rotation at 25 C was (A) [α] =+97.4 and (B) +86.8
D
(c1, CHCl3).
Figure 3

ACCEPTED MANUSCRIPT
6
"
6
'
2
A
CH OH
2
(
6
4
OCH2
3
5
"
(OCH
1
O
2
1
O
"
4'
O
5
4
"
OH
5'
1'
O
4
1
)
5
)
OH
HO
2"
OH
n
HO
2'
HO
3
"
m
6
3'
HO
2
OH
3
2
''
5
''
4''
3
''
3
'
1
'
6'
1
''
6''
6
"
6
'
CH OH
6
2
(OCH2
2
B
C
5"
OH
(OCH
O
2
1" 4'
O
O
1'
5
3
4"
HO
5
'
O
1
4
1
)
)
5
OH
HO
n
4
HO
2'
3
"
2"
m
3'
HO
2
OH
HO
3
6
3
"
2
"
4
"
5
"
6
'
1
'
6"
1
"
x
2'
6
1
(
2 4
5
OCH
5
2
3
O
1
)
2
6
4
OH
m
HO
3
OH
PPM
110
100
90
80
70
60
13
FIGURE 4 150 MHz C NMR Spectra of debenzylated polymers.
A) Copoly(LGG and LGTBE), (B) copoly(LGM and LGTBE), (C) poly(LGTBE) in D O
(
2
2
5
at 40 C. The specific rotation at 25 C was (A) [α] = +132.3 , (B) +134.2 ,
D
and (C) +139.6 , respectively. The proportions of the disaccharide units were (A) 7.8
mol% and (B) 7.1 mol%, respectively. Signals were assigned by H-H COSY and
HMQC spectra.
Figure 4

ACCEPTED MANUSCRIPT
A
B
-
CH2-
CH OBn
2
(
OCH2
-
CH2-
(OCH2
O
O
OBn
O
O
stretching
)
OBn
BnO
n
)
BnO
-CH2-
m
OBn
BnO
BnO
-CH2-
OBn
bending
bending
H-O-H
bending
CH OH
2
(
OCH2
(
OCH2
O
O
OH
HO
O
O
)
OH
n
)
HO
m
OH
HO
HO
OH
OH
3500
C-O-
1000
cm-1
500
4
000
3000
2500
2000
1500
Figure 5. FT-IR spectra (A) before and (B) after debenzylation of copoly(LGG and LGTBE)
measured by a KBr method.
The proportions of disaccharide units were (A) 10.0 mol% and (B) 7.8 mol%, respectively.
2
5
The specific rotations at 25 C was (A)[α]
=+78.1 (c1, CHCl ) and (B) +132.3 (c1, H O),
D
3
2
respectively.
Figure 5

ACCEPTED MANUSCRIPT
Highlights
New 3-O-branched 1, 6-anhydro di- and trisaccharide monomers were synthesized.
The polymerizability was compared with that of 4-O-branched disaccharide monomers.
The copolymerization with 1, 6-anhydro glucose gave the corresponding copolymers.
After debenzylation, 3-O-branched polysaccharides were obtained for the first time.