Synergistic solvent effect in 1,2-cis-glycoside formation

Article abstract of DOI:10.1016/j.tet.2007.10.087

Construction of three continuous 1,2-cis-α-glucosidic linkages was achieved in optimized solvent system. High-throughput optimization was conducted, by using substrates protected by perdeuterated benzyl (Bn-d₇) groups. It enabled facile evaluat

Full text of DOI:10.1016/j.tet.2007.10.087

Available online at www.sciencedirect.com
Tetrahedron 64 (2008) 92e102
www.elsevier.com/locate/tet
Synergistic solvent effect in 1,2-cis-glycoside formation
a,b,
Akihiro Ishiwata a,b, , Yuichi Munemura , Yukishige Ito
a,b
*
*
a RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
b CREST, JST, Kawaguchi 332-1102, Japan
Received 12 September 2007; received in revised form 23 October 2007; accepted 23 October 2007
Available online 26 October 2007
Abstract
Construction of three continuous 1,2-cis-a-glucosidic linkages was achieved in optimized solvent system. High-throughput optimization was
conducted, by using substrates protected by perdeuterated benzyl (Bn-d7) groups. It enabled facile evaluation of yield and stereoselectivity with
1H NMR and MALDI-TOF MS, respectively. We found that CHCl3 and ethereal solvent had a synergetic effect to enhance the a-selectivity. The
optimized solvent systems in CHCl3/CPME and CHCl3/Et2O were applied to the linear synthesis of Glca1/2Glca1/3Glca1/3Man
(Glc3Man1), which was achieved in 86% overall stereoselectivity.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: 1,2-cis-Glycosylation; a-Glucoside; Stereoselective; Solvent effect
1. Introduction
highly selective synthesis is generally difficult. There are a num-
ber of factors that may affect stereoselectivity and yield of
glycosylation.10,11 They include structures of substrates, pro-
moters, solvents, and temperatures.10 Among them, effects of
solvents are particularly important. As a rule of thumb, ethereal
solvents have a tendency to dictate the glycosylation in an
a-(axial) selective fashion, while nitrile solvents increase the
proportion of b-(equatorial) glycoside. However, the extent of
selectivity is difficult to predict precisely.
We recently developed a high-throughput screening (HTS)
system, which enabled rapid and quantitative evaluation of
glycosylation conditions.12 Herein, we describe the implemen-
tation of this system to the synthesis of the tetrasaccharide 1,
which consists of three continuous 1,2-cis-a-glycosidic linkag-
es.13e15 This tetrasaccharide corresponds to the non-reducing
terminal structure of tetradecasaccharide Glc3Man9GlcNAc2,
a common precursor of all N-linked glycans (Scheme 1).2,16
1,2-cis-O-Glycosides are widespread in nature.1 They are
important constituents of various biologically active natural
products and glycoconjugates.2 For example, a-glycosides of
D-glucose (Glc), L-fucose (Fuc), and a b-glycoside of D-mannose
(Man) are major constituents of asparagine-linked (N-linked)
glycoproteins and an a-glycoside of N-acetyl-D-galactosamine
(GalNAc) constitutes the core structure of serine/threonine-
linked (O-linked) glycoproteins.3 Heparin and heparan sulfate
are polysulfated glycosaminoglycans, which contain large num-
bers of a-linked N-acetyl-D-gluctosamine (GlcNAc) residues in
their repeating units.4 Biomedically important glycosphingo-
lipids such as Lewis (Le) antigens,5 globotriaosyl ceramide
(Gb3),6 and a-galactosyl ceramides7 contain a-linked Fuc or
D-galactose (Gal), and a-GalNAc and a-Gal are determinants
of human blood types.8
In most cases, 1,2-cis-glycosides are a-anomers, which con-
sist of axially oriented C(1)eO linkages. The formation of
a-glycosides is stereoelectronically preferred over correspond-
ing b-isomers, due to the anomeric effect.9 However, their
2. Results and discussions
The key in our HTS system is the use of isotopically
labeled protective group, perdeuterated benzyl ether (Bn-d7)
(Fig. 1).17 Benzyl (Bn) ether18 is one of the most widely
used hydroxy protective groups in carbohydrate chemistry.19
* Corresponding authors. Fax: þ81 48 462 4680 (Y.I.).
E-mail addresses: aishiwa@riken.jp (A. Ishiwata), yukito@riken.jp (Y. Ito).
0040-4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2007.10.087

A. Ishiwata et al. / Tetrahedron 64 (2008) 92e102
93
Scheme 1.
1
However, direct H NMR analysis of oligosaccharides having
enables the facile analyses of reactions performed in small
(mmol) scales. It allows for the systematic screening of various
conditions in a parallel fashion.
multiple O-Bn groups is problematic. This is because benzylic
methylene signals appear at 4e5 ppm as AB-quartets and ob-
scure the signals derived from anomeric protons. By employ-
ing Bn-d7 instead, all of these signals disappear and isomeric
ratios of glycosylated products can be estimated readily by
relative intensities of anomeric signals. In addition, the intro-
duction of Bn-d7 ethers enables facile evaluation of yield by
MALDI-TOF MS (Fig. 1). Each Bn-d7 contributes to increase
the molecular weight (M.W.) with þ7 Da compared to non-la-
beled Bn. Therefore, measurement of MS-spectrum of aliquot
of each reaction, which was mixed with a defined amount of
non-labeled substrates and product should provide the quanti-
tative estimates12 of yield and substrate recovery. Therefore,
combined use of MALDI-TOF MS and high-field NMR
In this study, application of the HTS system to the synthesis
of oligosaccharide having multiple 1,2-cis-glycosidic linkages
was investigated. We selected the tetrasaccharide Glc3Man1
(1) as our target, which consists of Glca1/2Glc (Linkage
1), Glca1/3Glc (Linkage 2), and Glca1/3Man (Linkage
3) substructures. It was planned to synthesize 1 from mannose
derivative 220 through consecutive couplings with selectively
protected glucosyl donors 3, 4, and 5 (Scheme 1).
For screening of reaction conditions, 2,3-O-Bn-d7 protected
donor 5D was employed and reacted with acceptors 9, 10, and
2D (Scheme 2), which were synthesized as shown in Scheme
3.20 Reactions were conducted in a parallel manner with

94
A. Ishiwata et al. / Tetrahedron 64 (2008) 92e102
(DME). Aromatic hydrocarbons (e.g., benzene and toluene)
exhibited poor selectivity.
Investigation of mixed solvent systems revealed that the
a-selectivity was markedly enhanced when halogenated and
ethereal solvents were mixed. For example, anomeric ratios
(a/b) in Et2O, CPME, CHCl3, and CH2Cl2 were 3.9:1, 4.6:1,
5.3:1, and 5.2:1, respectively, while those in 1:1 mixtures of
CHCl3/Et2O, CHCl3/CPME, and CH2Cl2/Et2O were 9.3:1,
8.7:1, and 8.2:1, respectively. These results suggest that coex-
istence of CHCl3 or CH2Cl2 and Et2O or CPME has a synergis-
tic effect in enhancing the a-selectivity.24,25 Somewhat
unexpectedly, dioxane was less effective than Et2O or CPME
as an ethereal component (entry 24). Interestingly, the selectiv-
ity was sensitive to the ratio of two components, being signif-
icantly lower when the proportion deviated from 1:1. Namely,
a/b ratios were 3.9:1, 4.4:1, 4.7:1, 9.3:1, 5.3:1, 4.3:1, and
5.3:1, when the Et2O content in CHCl3 was 100%, 90%,
75%, 50%, 25%, 10%, and 0%, respectively.
These results are intriguing as it is generally perceived that
ethereal solvents have a participating ability to coordinate car-
bocationic species (Fig. 2), while halogenated solvents such as
CHCl3 are more or less neutral. Our results showed that subtle
tuning of solvent composition, not only the mere presence of
an ethereal component, is important in maximizing the
selectivity.
Figure 1. HTS system. This system exploits perdeuterated benzyl (Bn-d7)
ether, and stereoselectivity and yield are evaluated by 1H NMR and
MALDI-TOF MS, respectively. And the systematic screening was conducted
in a parallel setting; reactions can be performed in w5 mmol scale with
w2 mg of substrates. MALDI-TOF MS of the crude mixtures was measured
with stock solutions of non-labeled compounds and yields were calculated
from relative peak heights. Anomeric ratios were estimated by 1H NMR
from relative intensities of H-1 signals (in C6D6) of a- and b-isomer.
w5 mmol (w2 mg) of acceptors, using 1.2 equiv of 5D,
4.2 equiv of methyl trifluoromethanesulfonate (MeOTf), and
1.5 equiv of 2,6-di-tert-butyl-4-methylpyridine (DTBMP) in
various solvents.21,22 A part of the results of glycosylation
with an acceptor 9 is listed in Table 1. Somewhat unexpect-
edly, halogenated solvents, CHCl3, or (CH2Cl)2 gave higher
selectivity than ethereal solvents such as Et2O, cyclopentyl
methyl ether (CPME),23 dioxane, and 1,2-dimethoxyethane
A 1:1 mixture of CHCl3 and ethereal solvents exhibited the
highest a-selectivity (11.4:1) for Glca1/3Glc linkage as well
(Linkage 2) (Table 2, entries 11 and 12).12 Again, the a-selec-
tivity was markedly higher than the cases where Et2O (3.8:1)
or CPME (6.9:1) was used alone. The use of CHCl3 alone (en-
try 1) gave equally high selectivity (10.9:1), while other
halogenated solvents such as CH2Cl2, (CH2Cl)2, and CHBr3
Scheme 2.

A. Ishiwata et al. / Tetrahedron 64 (2008) 92e102
95
Table 1
Effect of the solvent on 1,2-cis-glycosylations for Glc1/2Glc (Linkage 1)
Entry
Solvent
Yield (%)
a/b
1
CHCl3
CH2Cl2
73
75
80
75
92
85
100
86
25
45
25
72
70
91
97
96
98
93
72
100
84
55
93
69
5.28:1
5.17:1
4.61:1
3.93:1
5.47:1
1.99:1
2.45:1
1.93:1
5.00:1
3.52:1
1:1.27
1.25:1
8.68:1
4.33:1
5.31:1
9.27:1
4.67:1
4.35:1
5.73:1
6.10:1
8.17:1
3.84:1
8.19:1
4.42:1
2
3
CPME
Et2O
4
5
(CH2Cl)2
CCl4
6
7
Benzene
Toluene
8
9
Dioxane
DME
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
EtCN
t-BuCN
CHCl3/CPME
CHCl3/Et2O (9:1)
CHCl3/Et2O (4:1)
CHCl3/Et2O (1:1)
CHCl3/Et2O (1:4)
CHCl3/Et2O (1:9)
CHCl3/dioxane
(CH2Cl)2/Et2O
(CH2Cl)2/CPME
(CH2Cl)2/dioxane
CH2Cl2/Et2O
CH2Cl2/dioxane
between halogenated and ethereal solvents. In the latter case,
activation of the donor likely to generate ether-coordinated in-
termediates E(a) and E(b). It is plausible that glycosylation
proceeds through more abundant b-oriented E(b), giving
a-glycoside predominantly.
The formation of Glca1/3Man (Linkage 3) uniformly
proceeded in a highly selective manner in CHCl3, Et2O, or
CPME, among which Et2O was optimum. Again, a binary sys-
tem consisting of Et2O and CHCl3 gave the best result, in
terms of both yield and selectivity (Table 3).
From these results, a 1:1 mixture of CHCl3/Et2O (solvent-
A) or CHCl3/CPME (solvent-B) was judged to be suitable for
all linkages 1e3. Therefore, these solvent systems were
employed in the linear synthesis of the tetrasaccaharide 1
(Scheme 4A). The mannose derivative 2 was subjected to
sequential glycosylations with 320 (glycosylation-1), 420 (gly-
cosylation-2), and 5 (glycosylation-3). To begin with, coupling
with 3 gave 34 [a/b¼21.6:1 (solvent-A) or 17.4:1 (solvent-
B)], which was converted to the disaccharide acceptor 6.26
The latter was coupled with 4 [a/b¼18.7:1 (solvent-A) or
18.5:1 (solvent-B)] to provide 35. Subsequent detachment of
the PMB group gave 7, which was subjected to further coup-
ling with 5D [a/b¼21.6:1 (solvent-A) or 19.9:1 (solvent-B)] to
give 8. The overall selectivity from 2D was 86.7% or 85.5% in
solvent-A and -B, respectively.
Scheme 3. Reagents and conditions: (a) NaOMe, MeOH, quant. (b) 1,1-dime-
thoxycyclohexane, CSA, or TsOH$H2O, 90% (19), 71% (20), 77% (27), 60%
(31). (c) TolSH, BF3$OEt2, 91%, b. (d) Ag2O (1.5 equiv), BnBr or Bn-d7Br
(1.1 equiv), KI (0.2 equiv), CH2Cl2/DMF (10:1), rt, 24 h, 47% (21H/
22H¼2.92:1), 66% (21D/22D¼1.88:1), 60% (23/24¼2.0:1). (e) NaH, PMBCl
(1.2 equiv), DMF, 96% (3), 88% (4). (f) NaH, BnBr or Bn-d7Br (2.2 equiv),
DMF, 99% (5H), 70% (5D). (g) MPOH, TMSOTf, 75%. (h) TIPSCl, imidaz-
ole, DMF, 95%. (i) NaH, BnBr, or Bn-d7Br. (j) TBAF, 97% in two steps (2H),
86% in two steps (2D).
gave lower selectivity and aromatic solvents behaved poorly
(entries 2e6). At higher temperature (50 ꢀC), the a-selectivity
was drastically increased in CPME or CHCl3/CPME, reaching
as high as 17.6:1 or 19.5:1, although the yield was only mod-
est. On the other hand, significantly deteriorated selectivity
was observed in CHCl3 and (CH2Cl)2 (entries 18e21). These
results suggest that the origins of a-selectivity are different
High overall selectivity allowed us to conduct the whole
series of reactions without recourse of isomer separation after
each step. Thus, compound 2D was subjected to steps 1e5,
with all glycosylations performed in CHCl3/Et2O (solvent-A)
as shown in Scheme 4B to afford the desired all a-isomer of
Glc3Man1 derivative 8 in good overall yield in high purity
(47% from 2D). Deprotection of 8 gave 127 without incident.

96
A. Ishiwata et al. / Tetrahedron 64 (2008) 92e102
Figure 2. Plausible mechanism of a-selective glucosylation in the mixed solvent.
Table 2
Effect of the solvent on 1,2-cis-glycosylations for Glc1/3Glc (Linkage 2)
three continuous a-glucosidic linkages, was conducted using
solvent systems identified by HTP screening. Our study re-
vealed the synergistic effect of combined ethereal and halo-
genic solvents. Further effort toward facilitating and scaling
down the optimization through HTP system is in progress.
Entry
Solvent
Temp (ꢀC)
Yield (%)
a/b
1
CHCl3
CH2Cl2
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
50
50
50
50
60
61
96
47
65
66
78
91
87
43
100
98
78
55
76
100
51
100
97
42
50
10.9:1
5.89:1
3.68:1
5.34:1
1.86:1
1.46:1
6.91:1
3.79:1
4.11:1
3.78:1
11.4:1
11.4:1
3.64:1
7.28:1
8.72:1
3.23:1
4.09:1
4.95:1
4.18:1
17.6:1
19.5:1
2
3
(CH2Cl)2
CHBr3
Benzene
4
5
6
Toluene
CPME
4. Experimental
7
8
Et2O
Dioxane
DME
9
4.1. General procedures
10
11
12
13
14
15
16
17
18
19
20
21
CHCl3/CPME
CHCl3/Et2O
Toluene/CPME
CHCl3/dioxane
Toluene/dioxane
CHCl3/DME
Toluene/DME
CHCl3
Reactions sensitive to air and/or moisture were carried out
under nitrogen or argon atmosphere with anhydrous solvents.
Column chromatography was performed on silica gel 60N,
100e210 mesh (Kanto Kagaku Co., Ltd.). Preparative TLC
was performed on silica gel 60 F254, 0.5 mm thickness
(E. Merck). Gel filtration chromatography was performed on Se-
phadex LH-20 (Pharmacia). All other reagents were purchased
from Wako Pure Chemical Industries Ltd., Kanto Chemicals
Co., Inc., Tokyo Kasei Kogyo Co., or Aldrich Chemical Com-
(CH2Cl)2
CPME
CHCl3/CPME
pany. Melting points were determined with Buchi 510 melting
¨
point apparatus. Optical rotations were measured with a JASCO
DIP 370 polarimeter. 1H NMR spectra were recorded at
400 MHz on a JEOL JNM-AL 400 spectrometer and chemical
shifts are referred to internal tetramethylsilane (0 ppm) or
residual solvent peaks; CDCl3 (7.24 ppm), D2O (4.65 ppm),
or CD3OD (3.30 ppm). 13C NMR spectra were recorded at
100 MHz on the same instrument and chemical shifts are re-
ferred to internal CDCl3 (77.00 ppm), C6D6 (128.00 ppm), or
CD3OD (49.0 ppm). MALDI-TOF mass spectra were recorded
on a SHIMADZU Kompact MALDI AXIMA-CFR spectrome-
ter with 2,5-dihydroxybenzoic acid as the matrix. ESI-TOF
mass spectra were recorded on a JEOL AccuTOF JMS-
T700LCK with CF3CO2Na as an internal standard. FAB
mass spectra were recorded on a JEOL JMS HX110 with
Table 3
Effect of the solvent on 1,2-cis-glycosylations for Glc1/3Man (Linkage 3)
Entry
Solvent
Yield
(%)
a/b
1
2
3
4
5
CHCl3
CPME
94
90
83
92
74
22.1:1
22.1:1
35.3:1
39.9:1
22.2:1
Et2O
CHCl3/Et2O
CHCl3/CPME
3. Conclusion
In conclusion, a stereoselective synthesis of the tetrasac-
charide [Glca1/2Glca1/3Glca1/3Man], which contains

A. Ishiwata et al. / Tetrahedron 64 (2008) 92e102
97
˚
Scheme 4. Synthesis of Glc3Man1. Reagents and conditions: (a) MeOTf (4.2 equiv), DTBMP (1.5 equiv), 4 A MS, CHCl3/Et2O (1:1) (solvent-A) or CHCl3/CPME
(1:1) (solvent-B), rt, 24 h; 87% (21.6:1) (solvent-A), 76% (17.4:1) (solvent-B) (34); 81% (18.7:1) (solvent-A), 84% (18.5:1) (solvent-B) (35); 83% (21.6:1) (sol-
vent-A), 86% (19.9:1) (solvent-B) (8). (b) DDQ, CH2Cl2/H2O (10:1), rt, 18 h, 97% (6), 86% (7). (c) TFA, CH2Cl2, rt. (d) H2, Pd(OH)2, MeOH/H2O (2:1), 99% in
˚
two steps. (e) MeOTf (4.2 equiv), DTBMP (1.5 equiv), 4 A MS, Et2O/CHCl3 (1:1), rt, 48 h, 47% (8) from 2 (8/other isomers¼9.0:1). (f) DDQ, CH2Cl2/H2O (10:1),
rt, 36 h.
NBA as the matrix and PEG as an internal standard. Elemental
analyses were performed with a Fisons EA1108 instrument.
4.2.2. Determination of the yield by the quantitative
MALDI-TOF MASS analysis
The crude mixtures were diluted with 700 mL of CH3CN. A
4.0 mL measure of 1.0 mM standard solution of each of the
three non-labeled compounds was pre-mixed with 2.0 mL of
the crude solutions for MS analysis. The resulting solutions
were measured by MALDI-TOF MASS using the RASTER
function. The molar ratio of labeled to non-labeled compound
was obtained from the ratio of each value (mV) at the apex of
the ion peak of [MþNa]þ.
4.2. General procedure for the small scale screening
(Tables 1e3)
Each 100 mL of solution of acceptor 3D (96.6 mg,
208 mmol), donor 4D (121.2 mg, 250 mmol), and DTBMP
(76.8 mg, 374 mmol) in 6.0 mL of CH2Cl2 were pipetted into
multiplicate tubes, and the mixtures were evaporated by flash-
ing with N2 gas. In each tube, 3.47 mmol of acceptor,
4.17 mmol of donor, and 6.23 mmol of DTBMP were prepared
4.3. Synthesis
˚
for the reaction. After addition of 4 A MS (25 mg) and each
4.3.1. Methoxyphenyl 4,6-O-cyclohexylidene-2,3-di-O-
benzyl-b-D-glucopyranosyl-(1/3)-2-O-benzyl-4,6-
cyclohexylidene-b-D-glucopyranoside (12H)
After azeotropic removal with toluene, a mixture of 10H
(16.1 mg, 35.3 mmol) and 5H (20.0 mg, 42.5 mmol) was
solvent (200 mL) to the mixture, methyl trifluoromethanesulfo-
nate (2.0 mL, 18 mmol) was added to each tube. The mixtures
were magnetically stirred at room temperature for 24 h, and
the reactions quenched by triethylamine. The mixtures were
filtered through Celite, washed with saturated aqueous
NaHCO3 solution, dried over Na2SO4, and evaporated by
flashing with N2 to give crude mixtures. Results of glycosyla-
tion are listed in Tables 1e3, which were obtained by
following two analytical methods.
˚
dissolved in (CH2Cl)2 (2 mL) containing 4 A MS (250 mg,
freshly dried) and 2,6-di-tert-butyl-4-methylpyridine
(DTBMP, 10.7 mg, 51.1 mmol) and the mixture was stirred
for 10 min at room temperature. Solution of methyl trifluoro-
methanesulfonate (1 M, 51 mL, 51 mmol) in (CH2Cl)2 was
added to the mixture at the same temperature. After stirring
for 3d, the reaction was quenched by triethylamine and filtered
through Celite pad followed by washing with ethyl acetate.
The combined filtrate and washings were washed with satu-
rated aqueous NaHCO3 and brine, dried over Na2SO4, and
concentrated in vacuo. The residue was purified by gel
1
4.2.1. Determination of the stereoselectivity by H NMR
analysis
The anomeric ratios of products were estimated from the
relative intensities of H-1 signals (in C6D6) of a- and b-isomer
by analyzing the crude mixture.

98
A. Ishiwata et al. / Tetrahedron 64 (2008) 92e102
filtration chromatography (Bio beads SX-3, toluene/ethyl
acetate¼1:1) to give 12H as a mixture of isomers (24.8 mg,
85%, a/b¼5.00:1). The isomers were separated by PTLC (tol-
uene/ethyl acetate¼10:1) for characterization. Compound
J¼10.4 Hz, H-6Glc1, 1H), 3.68e3.74 (m, H-6Glc1, H-2Glc2
,
2H), 3.76e3.89 (m, H-2Glc1, H-4Glc1, H-4Glc2, H-6Glc2, 4H),
4.05 (dd, J¼10.8, 5.6 Hz, H-6Glc2, 1H), 4.14 (t, J¼9.2 Hz,
H-3Glc1, 1H), 4.29 (t, J¼9.2 Hz, H-3Glc2, 1H), 4.57e4.65
(m, H-5Glc2, 1H), 4.87 (d, J¼8.0 Hz, H-1Glc1, 1H), 5.89 (d,
J¼3.6 Hz, H-1Glc2, 1H), 6.69 (d, J¼9.2 Hz, MP, 2H), 6.98
(d, J¼9.2 Hz, MP, 2H); 13C NMR (C6D6, 100 MHz):
d 22.93, 23.12, 23.48, 23.63, 26.18, 26.28, 27.98, 28.35,
38.71, 38.75, 55.28, 61.60, 62.51, 64.01, 67.23, 74.38,
75.29, 75.93, 78.90, 79.99, 80.04, 97.76, 99.67, 99.71,
104.10, 114.90, 119.17, 151.69, 155.99 (þBn-d7ꢁ3).
MALDI-TOF MS: [MþNa]þ calcd for C52H41N21O12Na
923, found 923. HRMS FAB: [MþH]þ calcd for
C52H41N21O12Na 922.5457, found 922.5397. Compound
1
12Ha: H NMR (C6D6, 400 MHz): d 0.90e2.10 (m, cyclo-
hexylꢁ2, 10H), 3.08 (td, J¼10.0, 5.2 Hz, H-5Glc1, 1H), 3.27
(s, MeO, 3H), 3.56 (t, J¼10.8 Hz, H-6Glc1, 1H), 3.68e3.74
(m, H-6Glc1, H-2Glc2, 2H), 3.76e3.89 (m, H-2Glc1, H-4Glc1
,
H-4Glc2, H-6Glc2, 4H), 4.04 (dd, J¼10.4, 5.2 Hz, H-6Glc2, 1H),
4.14 (t, J¼9.2 Hz, H-3Glc1, 1H), 4.29 (t, J¼8.8 Hz, H-3Glc2
,
1H), 4.56e4.65 (m, H-5Glc2, 1H), 4.86 (s, Bn, 2H), 4.88 (d,
J¼8.0 Hz, H-1Glc1, 1H), 5.01 (d, J¼11.6 Hz, Bn, 1H), 5.06
(d, J¼10.8 Hz, Bn, 1H), 5.10 (d, J¼10.8 Hz, Bn, 1H), 5.19
(d, J¼11.6 Hz, Bn, 1H), 5.89 (d, J¼3.6 Hz, H-1Glc2, 1H),
6.69 (d, J¼9.2 Hz, MP, 2H), 6.98 (d, J¼9.2 Hz, MP, 2H),
7.10e7.75 (m, Ar, 15H); 13C NMR (C6D6, 100 MHz):
d 22.79, 22.98, 23.34, 23.49, 26.05, 26.14, 27.85, 28.21,
38.61 (ꢁ2), 55.18, 61.51, 62.42, 63.94, 67.15, 73.04, 74.31,
75.08, 75.20, 75.44, 75.86, 78.94, 80.05, 80.13, 97.68,
99.63, 99.67, 104.05, 114.89, 119.17, 127e129.10 (over up
under C6D6), 129.60, 138.32, 139.37, 139.91, 151.73,
156.02. MALDI-TOF MS: [MþNa]þ calcd for C52H62O12Na
901, found 901. HRMS FAB: [MþH]þ calcd for C52H63O12
879.4320, found 879.4348. Compound 12Hb: 1H NMR
(C6D6, 400 MHz): d 0.90e1.95 (m, cyclohexylꢁ2, 10H),
3.12e3.22 (m, H-5Glc1, 1H), 3.20e3.28 (m, H-5Glc2, 1H),
1
12Db: H NMR (C6D6, 400 MHz): d 0.90e1.95 (m, cyclo-
hexylꢁ2, 10H), 3.10e3.20 (m, H-5Glc1, 1H), 3.19e3.27
(m, H-5Glc2, 1H), 3.27 (s, MeO, 3H), 3.68e3.74 (m, H-6Glc1
,
H-2Glc2, H-3Glc2, H-6Glc2, 4H), 3.78e3.85 (m, H-4Glc1, H-
6Glc1, H-4Glc2, 3H), 3.89 (t, J¼8.0 Hz, H-2Glc1, 1H), 3.94
(dd, J¼9.2, 5.2 Hz, H-6Glc2, 1H), 4.17 (t, J¼8.8 Hz, H-3Glc1
,
1H), 4.91 (d, J¼7.6 Hz, H-1Glc1, 1H), 5.26 (d, J¼7.2 Hz,
H-1Glc2, 1H), 6.69 (d, J¼9.2 Hz, MP, 2H), 7.00 (d,
J¼9.2 Hz, MP, 2H); 13C NMR (C6D6, 100 MHz): d 22.97,
23.07, 23.40, 23.56, 26.18, 26.32, 28.14, 28.18, 38.65,
38.72, 55.30, 61.99, 62.24, 67.61, 67.77, 71.90, 74.44,
79.10, 81.99, 83.08, 83.37, 114.98, 118.97, 151.81,
155.97 (þBn-d7ꢁ3). MALDI-TOF MS: [MþNa]þ calcd
for C52H41N21O12Na 923, found 923. HRMS FAB:
[MþH]þ calcd for C52H41N21O12Na 922.5457, found
922.5459.
3.28 (s, MeO, 3H), 3.62e3.77 (m, H-6Glc1, H-2Glc2, H-3Glc2
,
H-6Glc2, 4H), 3.78e3.85 (m, H-4Glc1, H-6Glc1, H-4Glc2, 3H),
3.89 (t, J¼8.0 Hz, H-2Glc1, 1H), 3.95 (dd, J¼9.2, 5.2 Hz,
H-6Glc2, 1H), 4.17 (t, J¼8.8 Hz, H-3Glc1, 1H), 4.88 (d, J¼
11.6 Hz, Bn, 1H), 4.91 (d, J¼7.6 Hz, H-1Glc1, 1H), 4.93 (d,
J¼10.0 Hz, Bn, 1H), 4.96 (d, J¼12.0 Hz, Bn, 1H), 5.07 (d, J¼
12.0 Hz, Bn, 1H), 5.10 (d, J¼10.0 Hz, Bn, 1H), 5.11 (d,
J¼11.6 Hz, Bn, 1H), 5.26 (d, J¼7.2 Hz, H-1Glc2, 1H), 6.69
(d, J¼9.2 Hz, MP, 2H), 7.00 (d, J¼9.2 Hz, MP, 2H), 7.10e
7.50 (m, Ar, 15H); 13C NMR (C6D6, 100 MHz): d 22.83,
22.93, 23.26, 23.42, 26.05, 26.19, 28.01, 28.06, 38.53,
38.60, 55.20, 61.91, 62.15, 67.53, 67.70, 71.83, 74.35,
74.77, 75.52, 75.58, 78.67, 79.03, 82.05, 83.11, 83.39,
99.53, 99.76, 103.45, 103.55, 114.97, 118.96, 138.88,
139.37, 139.68, 151.84, 156.02. MALDI-TOF MS: [MþNa]þ
calcd for C52H62O12Na 901, found 901. HRMS FAB: [MþH]þ
calcd for C52H63O12 879.4320, found 879.4384.
4.4. Typical procedure for a-selective glycosylation
After azeotropic removal with toluene, to the mixture of
an acceptor (5e100 mmol) and a donor (1.2 equiv) in dry
CHCl3/Et2O (1:1) or CHCl3/CPME (1:1) (w15 mM) were
˚
added 4 A MS (ca. 125 mg/mL, freshly dried) and DTBMP
(1.5 equiv) and the mixture was stirred for 10 min at room
temperature. MeOTf (4.2 equiv) was added to the mixture.
After stirring for 24 h at the same temperature, the reaction
was quenched with triethylamine followed by filtration
through Celite pad and washing of pad with ethyl acetate.
The combined solutions were washed with saturated aqueous
NaHCO3 and brine, dried over Na2SO4, and concentrated in
vacuo. The residue was purified by gel filtration (Bio beads
SX-3, toluene/ethyl acetate¼1:1) to give the mixture of the
isomers.
4.3.2. Methoxyphenyl 4,6-O-cyclohexylidene-2,3-di-O-
(benzyl-d7)-b-D-glucopyranosyl-(1/3)-2-O-(benzyl-d7)-
4,6-O-cyclohexylidene-b-D-glucopyranoside (12D)
This compound was prepared from 10D and 5D according
to the procedure described for compound 12H. The crude mix-
1
ture was subjected to MALDI-TOF Mass and H NMR mea-
4.4.1. Methoxyphenyl 4,6-O-cyclohexylidene-2,3-di-O-
benzyl-a-D-glucopyranosyl-(1/2)-3-O-benzyl-4,6-O-
cyclohexylidene-b-D-glucopyranoside (11H)
surements, which provided the estimations of yield (70%)
and selectivity (a/b¼5.26:1). Finally, the isomers were sepa-
rated by PTLC (SiO2, toluene/ethyl acetate¼10:1) for the
This compound was synthesized from 9H and 5H accord-
ing to the procedure described in Section 4.4. (94%,
1
a/b¼8.06:1 in CHCl3/CPME). H NMR (C6D6, 400 MHz):
1
sake of characterization. Compound 12Da: H NMR (C6D6,
a-isomer: d 1.15e2.10 (m, cyclohexylꢁ2, 20H), 2.96 (td,
J¼9.6, 5.2 Hz, H-5Glc1, 1H), 3.28 (s, OMe, 3H), 3.56 (t,
400 MHz): d 0.90e2.10 (m, cyclohexylꢁ2, 10H), 3.08 (td,
J¼10.0, 5.2 Hz, H-5Glc1, 1H), 3.27 (s, MeO, 3H), 3.55 (t,
J¼10.4 Hz, H-4Glc1, 1H), 3.64e3.74 (m, H-2Glc1, H-3Glc2
,

A. Ishiwata et al. / Tetrahedron 64 (2008) 92e102
99
H-6Glc2, 4H), 3.80 (t, J¼10.0 Hz, H-6Glc1, 1H), 3.83 (t, J¼
9.2 Hz, H-4Glc1, 1H), 4.05 (dd, J¼10.0, 5.2 Hz, H-6Glc1, 1H),
38.94, 39.01, 55.42, 61.92, 62.66, 65.66, 66.80, 71.89,
72.43, 73.79, 74.89, 75.11, 75.31, 78.80, 79.46, 80.21, 98.82
(JCeH¼174.0 Hz), 98.93 (JCeH¼169.1 Hz), 100.13, 100.36,
115.21, 118.48, 125.89, 127.70e129.52 (overlapped on
C6D6), 138.98, 139.61, 139.99, 150.55, 155.88. HRMS ESI-
TOF: [MþNa]þ calcd for C52H62O12Na 901.4139, found
901.4084.
4.18 (t, J¼8.4 Hz, H-3Glc1, 1H), 4.26 (t, J¼9.6 Hz, H-3Glc1
,
1H), 4.55 (d, J¼12.0 Hz, Bn, 1H), 4.67 (d, J¼12.0 Hz, Bn,
1H), 4.78 (td, J¼10.0, 5.6 Hz, H-5Glc1, 1H), 4.91 (d,
J¼8.0 Hz, H-1Glc2, 1H), 5.03 (d, J¼12.0 Hz, Bn, 1H), 5.07
(d, J¼10.8 Hz, Bn, 1H), 5.11 (d, J¼10.8 Hz, Bn, 1H), 5.20
(d, J¼12.0 Hz, Bn, 1H), 5.91 (d, J¼4.0 Hz, H-1Glc1, 1H),
6.67e7.83 (m, Ar, 19H); 13C NMR (C6D6, 100 MHz): a-iso-
mer: d 22.80, 22.98, 23.39, 23.52, 25.94, 26.16, 27.91,
28.21, 38.55, 38.70, 55.25, 61.62, 62.36, 64.03, 67.05,
73.43, 74.34, 74.91, 75.08, 75.17, 76.48, 78.08, 79.04,
80.26, 97.29, 99.61 (ꢁ2), 102.65, 114.91, 118.64, 127.49e
129.89 (overlapped on C6D6), 138.57, 139.02, 139.95,
151.05, 155.91. HRMS ESI-TOF: [MþNa]þ calcd for
C52H62O12Na 901.4139, found 901.4117.
4.4.4. Methoxyphenyl 4,6-O-cyclohexylidene-2,3-di-O-
(benzyl-d7)-a-D-glucopyranosyl-(1/3)-2-O-(benzyl-d7)-
4,6-O-cyclohexylidene-a-D-mannopyranoside (13D)
This compound was prepared from 5D and 2D and isolated
by PTLC (hexane/ethyl acetate¼5:1). [a]2D7 101.59 (c 1.0,
1
CHCl3). H NMR (C6D6, 400 MHz): d 1.00e2.10 (m, cyclo-
hexylꢁ2, 20H), 3.30 (s, OMe, 3H), 3.68e3.78 (m, H-2Glc
,
H-6Man, 3H), 3.80 (t, J¼9.6 Hz, H-4Glc, 1H), 3.84 (t,
J¼10.4 Hz, H-6Glc, 1H), 3.99 (br t, H-2Man, 1H), 4.02 (t,
J¼10.4, 5.2 Hz, H-6Glc, 1H), 4.05e4.18 (m, H-5Man, H-5Glc
2H), 4.26 (t, J¼9.2 Hz, H-3Glc, 1H), 4.59e4.72 (m, H-3Man
,
,
4.4.2. Methoxyphenyl 4,6-O-cyclohexylidene-2,3-di-O-
(benzyl-d7)-a-D-glucopyranosyl-(1/2)-2-O-(benzyl-d7)-
4,6-O-cyclohexylidene-b-D-glucopyranoside (11D)
H-4Man, 2H), 5.53 (d, J¼1.6 Hz, H-1Man, 1H), 5.82 (d, J¼
4.0 Hz, H-1Glc, 1H), 6.67e7.57 (m, Ar, 19H); 13C NMR
(C6D6, 100 MHz): d 23.93, 23.06, 23.48, 23.57, 26.20,
26.21, 28.24, 28.29, 38.82, 38.90, 55.28, 61.78, 62.50,
64.90, 66.65, 71.73, 73.62, 74.96, 78.51, 79.17, 79.94,
98.65, 98.77, 99.92, 100.15, 114.98, 118.26, 127.70e129.52
(overlapped with C6D6), 138.42, 139.04, 139.43, 150.29,
155.60. ESI-TOF MS: [MþNa]þ calcd for C52H41D21O12Na
922.55, found 922.54. HRMS ESI-TOF: [MþNa]þ calcd for
C52H41D21O12Na 922.5457, found 922.5496.
This compound was synthesized from 9D and 5D as de-
scribed for the synthesis of 12H except that the reaction
time was 24 h (95%, a/b¼3.99:1). 1H NMR (C6D6,
400 MHz): a-isomer: d 1.15e2.10 (m, cyclohexylꢁ2, 20H),
2.96 (td, J¼10.0, 5.6 Hz, H-5Glc1, 1H), 3.28 (s, OMe, 3H), 3.56
(t, J¼10.4 Hz, H-4Glc1, 1H), 3.62e3.74 (m, H-2Glc1, H-3Glc2
,
H-6Glc2, 4H), 3.80 (t, J¼10.0 Hz, H-6Glc1, 1H), 3.83 (t,
J¼9.2 Hz, H-4Glc1, 1H), 4.06 (dd, J¼10.0, 5.2 Hz, H-6Glc1
,
1H), 4.17 (t, J¼8.0 Hz, H-2Glc1, 1H), 4.26 (t, J¼9.2 Hz,
H-3Glc1, 1H), 4.78 (td, J¼10.0, 5.2 Hz, H-5Glc1, 1H), 4.91 (d,
J¼7.6 Hz, H-1Glc2, 1H), 5.91 (d, J¼3.6 Hz, H-1Glc1, 1H),
6.67e6.93 (m, Ar, 4H); 13C NMR (C6D6, 100 MHz): a-isomer:
d 22.80, 22.98, 23.38, 23.51, 25.93, 26.16, 27.91, 28.21, 38.54,
38.71, 55.25, 61.61, 62.36, 64.00, 67.03, 74.93, 75.18, 76.47,
77.88, 78.93, 80.16, 97.31, 99.61 (ꢁ2), 102.07, 114.90, 118.64,
151.04, 155.90 (þBn-d7ꢁ3). HRMS ESI-TOF: [MþNa]þ calcd
for C52H41D21O12Na 922.5457, found 922.5457.
4.4.5. Methoxyphenyl 2-O-(benzyl-d7)-3-O-
(4-methoxybenzyl)-4,6-O-cyclohexylidene-a-D-glucopyranosyl-
(1/3)-2-O-(benzyl-d7)-4,6-O-cyclohexylidene-
a-D-mannopyranoside (34)
This compound was synthesized from 2D and 3 according
to the procedure described in Section 4.4. (87%, a/b¼21.6:1
in CHCl3/Et2O; 76%, a/b¼17.4:1 in CHCl3/CPME). [a]D29
1
88.1 (c 0.54, CHCl3). H NMR (C6D6, 400 MHz): d 1.00e
4.4.3. Methoxyphenyl 4,6-O-cyclohexylidene-2,3-di-O-
benzyl-a-D-glucopyranosyl-(1/3)-2-O-benzyl-4,6-O-
cyclohexylidene-a-D-mannopyranoside (13H)
2.10 (m, cyclohexylꢁ2, 20H), 3.26 (s, OMe, 3H), 3.29 (s,
OMe, 3H), 3.68e3.78 (m, H-2Glc, H-6Man, 3H), 3.81 (t,
J¼9.6 Hz, H-4Glc, 1H), 3.84 (t, J¼10.8 Hz, H-6Glc, 1H),
This compound was synthesized from 2H and 5H accord-
ing to the general procedure described in Section 4.4. (91%,
3.99 (br s, H-2Man, 1H), 4.03 (t, J¼10.8, 5.6 Hz, H-6Glc
,
1H), 4.05e4.14 (m, H-5Man, 1H), 4.15 (td, J¼10.4, 4.8 Hz,
H-5Glc, 1H), 4.27 (t, J¼9.2 Hz, H-3Glc, 1H), 4.62e4.72 (m,
H-3Man, H-4Man, 2H), 4.97 (d, J¼11.2 Hz, PMB, 1H), 5.08
(d, J¼11.2 Hz, PMB, 1H), 5.53 (d, J¼2.0 Hz, H-1Man, 1H),
5.82 (d, J¼4.0 Hz, H-1Glc, 1H), 6.66e7.57 (m, Ar, 18H);
13C NMR (C6D6, 100 MHz): d 22.94, 23.10, 23.49, 23.61,
26.20, 26.27, 28.24, 28.32, 38.86, 54.85, 55.27, 61.78,
62.53, 64.94, 66.66, 71.77, 73.55, 74.68, 74.85, 75.05,
78.18, 79.14, 79.96, 98.67, 98.83, 99.92, 100.15, 113.96,
114.98, 118.26, 127.88e128.78 (overlapped on C6D6),
129.78, 131.74, 138.46, 139.14, 150.28, 155.59, 159.53.
ESI-TOF MS: [MþNa]þ calcd for C53H50D14O13Na 945.51,
found 945.5119. HRMS ESI-TOF: [MþNa]þ calcd for
C53H50D14O13Na 945.5123, found 945.5119.
1
a/b¼22:1 in CHCl3/CPME). [a]2D8 109.8 (c 1.0, CHCl3). H
NMR (C6D6, 400 MHz): d 1.00e2.10 (m, cyclohexylꢁ2,
20H), 3.29 (s, OMe, 3H), 3.68e3.78 (m, H-2Glc, H-6Man
,
3H), 3.80 (t, J¼9.6 Hz, H-4Glc, 1H), 3.84 (t, J¼10.4 Hz,
H-6Glc, 1H), 3.99 (br t, H-2Man, 1H), 4.02 (t, J¼10.4,
5.2 Hz, H-6Glc, 1H), 4.05e4.18 (m, H-5Man, H-5Glc, 2H),
4.26 (t, J¼9.2 Hz, H-3Glc, 1H), 4.49 (d, J¼11.2 Hz, Bn, 1H),
4.59e4.72 (m, H-3Man, H-4Man, 2H), 4.76 (d, J¼12.0 Hz,
Bn, 1H), 4.84 (d, J¼11.2 Hz, Bn, 1H), 4.96 (d, J¼12.0 Hz,
Bn, 1H), 4.99 (d, J¼11.6 Hz, Bn, 1H), 5.10 (d, J¼11.6 Hz, Bn,
1H), 5.53 (d, J¼1.6 Hz, H-1Man, 1H), 5.82 (d, J¼3.6 Hz,
H-1Glc, 1H), 6.67e7.57 (m, Ar, 19H); 13C NMR (C6D6,
100 MHz): d 23.96, 23.03, 23.59, 23.67, 26.33, 28.34, 28.40,

100
A. Ishiwata et al. / Tetrahedron 64 (2008) 92e102
4.4.6. Methoxyphenyl 2-O-(benzyl-d7)-4,6-O-
cyclohexylidene-a-D-glucopyranosyl-(1/3)-2-O-(benzyl-d7)-
4,6-O-cyclohexylidene-a-D-mannopyranoside (6)
TOF: [MþNa]þ calcd for C72H67D21O18Na 1284.7187, found
1284.7138.
To a solution of compound 34 (17.0 mg, 18.4 mmol) in
CH2Cl2/H2O (10:1, 3.3 mL) was added DDQ (5.8 mg,
28.0 mmol) and stirred at room temperature for 18 h. The reac-
tion was quenched with ascorbic acid/citric acid buffer, which
was prepared from L-ascorbic acid (0.7 g), citric acid monohy-
drate (1.2 g), and NaOH (0.92 g) in H2O (100 mL), and
extracted with CHCl3. The combined solutions were washed
with brine, dried over Na2SO4, and concentrated in vacuo.
The resulting residue was purified by PTLC (hexane/ethyl
acetate¼10:1ꢁ2) to give the title compound (14.4 mg, 97%).
4.4.8. Methoxyphenyl 3-O-(benzyl-d7)-4,6-O-
cyclohexylidene-a-D-glucopyranosyl-(1/3)-2-O-(benzyl-d7)-
4,6-O-cyclohexylidene-a-D-glucopyranosyl-(1/3)-2-O-
(benzyl-d7)-4,6-O-cyclohexylidene-a-D-mannopyranoside (7)
This compound was synthesized from 35 according to the
procedure described for the synthesis of 6 (86%). [a]D29
1
130.9 (c 0.77, CHCl3). H NMR (C6D6, 400 MHz): d 0.90e
2.00 (m, cyclohexylꢁ3, 30H), 2.71 (d, J¼8.4 Hz, OH, 1H),
3.30 (s, OMe, 3H), 3.54 (dd, J¼9.2, 3.6 Hz, H-2Glc1, 1H),
3.62 (t, J¼9.6 Hz, H-4Glc1, 1H), 3.65e3.80 (m, H-4Glc2, H-
1
[a]2D8 ꢂ125.2 (c 1.00, CHCl3). H NMR (C6D6, 400 MHz):
6Glc1, H-6Glc2, H-6Man, 5H), 3.85e4.00 (m, H-2Glc2, H-6Glc1
H-6Glc2, H-2Man, 4H), 4.02e4.16 (m, H-5Glc1, H-5Glc2
,
,
d 1.00e2.10 (m, cyclohexylꢁ2, 20H), 2.48 (br s, OH, 1H),
3.29 (s, OMe, 3H), 3.59 (dd, J¼9.2, 4.0 Hz, C2-HGlc, 1H),
H-5Man1, 3H), 4.42e4.52 (m, H-3Glc1, H-3Glc2, 2H), 4.62e4.65
(m, H-3Man, H-4Man, 4H), 3.92 (dd, J¼2.8, 1.6 Hz, ManH-2,
1H), 4.05e4.14 (m, Glc1H-3, Glc2H-3, 1H), 5.54e5.57 (m,
H-1Glc2, H-1Man, 2H), 5.86 (d, J¼3.6 Hz, H-1Glc1, 1H),
6.68e6.92 (m, Ar, 4H); 13C NMR (C6D6, 100 MHz):
d 22.38 (ꢁ2), 22.54, 22.80, 22.89, 23.12, 25.57 (ꢁ2), 25.76,
27.67, 27.77, 38.09, 38.37, 38.47, 54.83, 61.26, 61.70, 61.91
(ꢁ2), 64.00, 64.25, 66.27, 71.25, 73.29, 73.69, 73.86, 74.11
(ꢁ2), 74.04, 77.13, 78.66, 79.91, 97.54, 98.27, 99.28, 99.86,
100.07, 100.61, 114.71, 117.99, 137.99, 150.07, 155.46.
ESI-TOF MS: [MþNa]þ calcd for C64H59D21O17Na
1164.66, found 1164.66. HRMS ESI-TOF: [MþNa]þ calcd
for C64H59D21O17Na 1164.6611, found 1164.6618.
3.69 (t, J¼9.2 Hz, C4-HGlc, 1H), 3.73e3.79 (m, C6-HMan
,
2H), 3.80 (t, J¼10.4 Hz, C6-HGlc, 1H), 3.98 (t, J¼1.2 Hz,
C2-HMan, 1H), 4.02 (dd, J¼10.4, 5.6 Hz, C6-HGlc, 1H),
4.04e4.18 (m, C5-HMan, C5-HGlc, 2H), 4.39 (t, J¼9.2 Hz,
C3-HGlc, 1H), 4.65e4.73 (m, C3-HMan, C3-HMan, 2H), 5.53
(d, J¼1.2 Hz, C1-HMan, 1H), 5.82 (d, J¼4.0 Hz, C1-HGlc
,
1H), 6.68e6.90 (m, Ar, 2H); 13C (C6D6, 100 MHz): d 22.38,
22.54, 22.85, 22.92, 25.64, 25.71, 27.73, 38.28, 38.40, 54.83,
61.31, 61.89, 64.26, 66.24, 70.81, 71.31, 73.27, 73.48, 78.77,
79.49, 97.85, 98.49, 99.72, 99.83, 114.69, 117.97, 126.85e
128.65 (overlapped on C6D6), 138.15, 138.47, 150.07, 155.42.
MALDI-TOF MS: [MþNa]þ calcd for C45H42D14NaO12
825.45, found 825.50. HRMS ESI-TOF: [MþNa]þ calcd for
C45H42D14NaO12 825.4548, found 825.4565.
4.4.9. Methoxyphenyl 2,3-di-O-(benzyl-d7)-4,6-
cyclohexylidene-a-D-glucopyranosyl-(1/2)-3-O-(benzyl-d7)-
4,6-O-cyclohexylidene-a-D-glucopyranosyl-(1/3)-2-O-
(benzyl-d7)-4,6-O-cyclohexylidene-a-D-glucopyranosyl-
(1/3)-2-O-(benzyl-d7)-4,6-O-cyclohexylidene-a-D-
mannopyranoside (8)
4.4.7. Methoxyphenyl 3-O-(benzyl-d7)-4,6-O-
cyclohexylidene-2-O-(4-methoxybenzyl)-a-D-
glucopyranosyl-(1/3)-2-O-(benzyl-d7)-4,6-O-
cyclohexylidene-a-D-glucopyranosyl-(1/3)-2-O-(benzyl-d7)-
4,6-O-cyclohexylidene-a-D-mannopyranoside (35)
This compound was synthesized from 6 and 4 according to
the procedure described in Section 4.4. (81%, a/b¼18.8:1 in
CHCl3/Et2O; 84%, a/b¼18.5:1 in CHCl3/CPME). [a]2D9 90.8
This compound was synthesized from 7 and 5D according
to the procedure described in Section 4.4. (83%, a/b¼21.6:1
in CHCl3/Et2O; 86%, a/b¼19.9:1 in CHCl3/CPME). [a]D26
1
136.1 (c 0.87, CHCl3). H NMR (C6D6, 400 MHz): d 0.90e
1
(c 1.0, CHCl3). H NMR (C6D6, 400 MHz): d 1.22e2.05 (m,
2.15 (m, cyclohexylꢁ4, 40H), 3.29 (s, OMe, 3H), 3.52e3.73
cyclohexyl, 30H), 3.30 (s, MeO, 3H), 3.32 (s, MeO, 3H),
3.66e3.78 (m, H-2Glc1, H-6Glc1, H-2Glc2, H-6Glc2, H-6Man
(m, H-6Glc1, H-2Glc2, H-6Glc2, H-6Glc3, H-6Man, 5H), 3.82 (t,
,
J¼10.4 Hz, H-4Glc1, 1H), 3.88 (dd, J¼9.6, 3.6 Hz, H-2Glc3
,
6H), 3.79 (t, J¼10.0 Hz, H-4Glc1, 1H), 3.94 (t, J¼9.6 Hz, H-
1H), 3.90e4.00 (m, H-6Glc1, H-4Glc2, H-6Glc2, H-4Glc3, H-
4Glc2, 1H), 3.95e4.03 (m, H-5Glc1, H-6Glc1, H-6Glc2, H-2Man
,
6Glc3, H-2Man, H-6Man, 7H), 4.02e4.13 (m, H-5Glc2, H-5Man
,
3H), 4.05e4.13 (m, H-5Glc2, H-5Man, 2H), 4.31 (t, J¼9.2 Hz,
H-3Glc1, 1H), 4.65 (t, J¼9.2 Hz, H-3Glc2, 1H), 4.68e4.75 (m,
H-3Man, H-4Man, 2H), 4.84 (d, J¼11.6 Hz, PMB, 1H), 4.88
(d, J¼11.6 Hz, PMB, 1H), 5.54 (d, J¼1.2 Hz, H-1Man, 1H),
5.90 (d, J¼3.6 Hz, H-1Glc1/H-1Glc2, 1H), 5.92 (d, J¼3.6 Hz,
H-1Glc1/H-1Glc2, 1H), 6.66e7.42 (m, Ar, 8H); 13C NMR
(C6D6, 100 MHz): d 22.57 (ꢁ3), 22.90, 22.99, 23.13, 25.57,
25.78 (ꢁ2), 27.66 (ꢁ2), 27.89, 32.26, 32.45 (ꢁ2), 54.49,
54.83, 61.28, 61.67, 63.55, 63.97, 66.29, 71.42, 72.47, 72.85
(ꢁ2), 74.93 (ꢁ2), 76.86, 78.51, 78.64, 79.52, 97.29, 97.58,
98.48, 99.19, 99.62, 99.87, 113.75, 114.68, 118.00, 150.09,
155.41, 159.41 (þBn-d7ꢁ3). ESI-TOF MS: [MþNa]þ calcd
for C72H67D21O18Na 1284.72, found 1284.74. HRMS ESI-
2H), 4.16 (dd, J¼9.2, 4.0 Hz, H-2Glc1, 1H), 4.27 (t,
J¼9.2 Hz, H-3Glc1, 1H), 4.42 (t, J¼9.2 Hz, H-3Glc3, 1H),
4.45 (td, J¼10.4, 5.2 Hz, H-5Glc3, 1H), 4.59 (td, J¼10.4,
5.6 Hz, H-5Glc1, 1H), 4.66e4.75 (m, H-3Glc2, H-3Man
,
H-4Man, 3H), 5.54 (d, J¼1.6 Hz, H-1Man, 1H), 5.68 (d,
J¼4.0 Hz, H-1Glc3, 1H), 5.85 (d, J¼3.6 Hz, H-1Glc2, 1H),
6.20 (d, J¼4.0 Hz, H-1Glc1, 1H), 6.66e6.90 (m, Ar, 4H); 13C
NMR (C6D6, 100 MHz): d 22.59, 22.82 (ꢁ2), 22.94, 23.10,
23.20, 23.32, 23.34, 25.87, 25.95 (ꢁ3), 27.89, 28.06 (ꢁ2),
28.51, 38.42 (ꢁ3), 38.67, 55.08, 61.56, 61.71, 62.12, 62.17,
63.52, 64.04, 64.23, 66.56, 71.61, 71.90, 73.14, 74.62,
74.94, 75.33, 75.39, 77.43, 77.47, 78.60, 78.80, 79.85,
95.08, 95.45, 97.79, 98.62, 99.46, 99.66, 99.75, 100.12,

A. Ishiwata et al. / Tetrahedron 64 (2008) 92e102
101
114.93, 118.23, 125.50e129.50 (overlapped on C6D6), 138.31,
138.47, 139.48, 150.34, 155.67. ESI-TOF MS: [MþNa]þ
calcd for C90H75D35O22Na 1600.96, found 1600.94. HRMS
ESI-TOF: [MþNa]þ calcd for C90H75D35O22Na 1600.9583,
found 1600.9610.
the mixture of the isomers. The resulting residue was
purified by PTLC (toluene/ethyl acetate¼5:1) to give the title
compound as the major isomer (82.3 mg, 47%, 8/other
isomers¼9.0:1).
4.4.11. Methoxyphenyl a-D-glucopyranosyl-(1/2)-a-D-
glucopyranosyl-(1/3)-a-D-glucopyranosyl-(1/3)-a-D-
mannopyranoside (1)
4.4.10. Preparation of 8 from 2D
Step-1: after azeotropic removal with toluene, to the mix-
ture of acceptor 2D (50.0 mg, 0.108 mmol) and donor 3
(75.5 mg, 0.129 mmol) in dry CHCl3/Et2O (1:1) (4.0 mL)
To a solution of compound 8 (8.7 mg, 5.50 mmol) in CHCl3
(2 mL) was added trifluoroacetic acid (TFA, 0.2 mL) and
stirred at room temperature for 2 h. The reaction mixture
was concentrated in vacuo followed by azeotropic removal
with toluene. Hydrogenolysis of resulting residue was carried
out in the presence of Pd(OH)2 (10 mg) in MeOH/H2O (2:1,
3 mL) for 4 h at room temperature. The mixture was filtered
through Celite and filtrate was concentrated in vacuo. The res-
idue was purified by gel filtration (Sephadex LH-20, MeOH/
H2O, 1:1) to give the title compound (4.2 mg, 99%). [a]D28
˚
were added 4 A MS (500 mg, freshly dried) and DTBMP
(33.3 mg, 0.162 mmol) and the mixture was stirred for
10 min at room temperature. MeOTf (51.3 mL, 0.453 mmol)
was added to the mixture. After stirring for 48 h at the same
temperature, the reaction was quenched with triethylamine fol-
lowed by filtration through Celite pad and through washing of
the filter cake with ethyl acetate. Combined filtrates were
washed with saturated aqueous NaHCO3 and brine, dried
over Na2SO4, and concentrated in vacuo.
Step-2: to a solution of the above mixture in CH2Cl2/H2O
(10:1, 3.3 mL) was added DDQ (38.0 mg, 0.184 mmol) and
stirred at room temperature for 18 h. The reaction was
quenched with ascorbic acid/citric acid buffer and extracted
with CHCl3. The combined solutions were washed with
brine, dried over Na2SO4, and concentrated in vacuo. The
residue was filtrated through Bio beads SX-3 with elution
of toluene/ethyl acetate (1:1) to give the mixture of
Glc1Man1 isomers. The mixture was coevaportated with tol-
uene and used for the next glycosylation without further
purification.
1
76.3 (c 0.48, H2O). H NMR (CD3OD/D2O¼1:1, 400 MHz):
d 3.43 (t, J¼10.0 Hz, H-4Glc3, 1H), 3.43 (t, J¼9.6 Hz, H-
4Glc1, 1H), 3.58 (dd, J¼10.0, 3.6 Hz, H-2Glc3, 1H), 3.58 (dd,
J¼10.0, 4.0 Hz, H-2Glc2, 1H), 3.63 (dd, J¼10.0, 4.0 Hz,
H-2Glc1, 1H), 3.64e3.80 (m, H-3Glc1, H-6Glc1, H-3Glc2
H-4Glc2, H-5Glc2, H-6Glc2, H-3Glc3, H-6Glc3, H-5Man, H-6Man
14H), 3.76 (s, OMe, 3H), 3.88e4.50 (m, H-5Glc1, H-5Glc3
,
,
,
H-3Man, H-4Man, 3H), 4.26 (t, J¼1.2 Hz, H-2Man, 1H), 5.09
(d, J¼4.0 Hz, H-1Glc3, 1H), 5.23 (d, J¼4.0 Hz, H-1Glc2, 1H),
5.36 (d, J¼1.2 Hz, H-1Man, 1H), 5.46 (d, J¼3.6 Hz, H-1Glc1
,
1H), 6.87 (d, J¼8.8 Hz, MP, 2H), 7.06 (d, J¼8.8 Hz, MP,
2H); 13C NMR (D2O, 100 MHz): d 56.46, 60.78, 60.94
(ꢁ2), 61.21, 66.45, 67.43, 69.84, 69.89, 70.37, 70.50, 70.96,
71.81, 71.90, 72.06, 72.39, 72.59, 73.44, 74.06, 79.08,
80.40, 96.43, 97.13, 99.64, 101.34, 115.56, 119.23, 149.99,
155.05. HRMS ESI-TOF: [MþNa]þ calcd for C31H48O22Na
795.2535, found 795.2626. HRMS FAB: [MþNa]þ calcd for
C31H48O22Na 795.2535, found 795.2507.
Step-3: the above mixture was mixed with donor 4
(75.5 mg, 0.129 mmol) in dry CHCl3/Et2O (1:1) (4.0 mL),
˚
were added 4 A MS (500 mg, freshly dried) and DTBMP
(33.3 mg, 0.162 mmol), and MeOTf (51.3 mL, 0.453 mmol)
was added to the mixture after 10 min. After stirring for
48 h at the same temperature, the reaction was quenched
with triethylamine and processed as described in Step-1.
Step-4: to a solution of the above mixture in CH2Cl2/H2O
(10:1, 3.3 mL) was added DDQ (38.0 mg, 0.184 mmol) and
stirred at room temperature for 36 h. The reaction was pro-
cessed as described in Step-2. The residue was filtrated through
Bio beads SX-3 with elution of toluene/ethyl acetate (1:1) to
give the mixture of Glc2Man1 isomers. The mixture was used
for next glycosylation without further purification.
Acknowledgements
This work was partly supported by ‘Ecomolecular Science’
and ‘Chemical Biology’ programs in RIKEN, and a Grant-in-
Aid for Encouragement of Young Scientist from the Ministry
of Education, Culture, Sports, Science, and Technology (No.
18710196). We thank Ms. A. Takahashi for her technical
assistance.
Step-5: after azeotropic removal with toluene, to the solu-
tion of the above mixture and donor 5D (62.8 mg,
0.129 mmol) in dry CHCl3/Et2O (1:1) (4.0 mL) were added
˚
4 A MS (500 mg, freshly dried) and DTBMP (33.3 mg,
Supplementary data
0.162 mmol) and the mixture was stirred for 10 min at room
temperature. MeOTf (51.3 mL, 0.453 mmol) was added to
the mixture. After stirring for 48 h at the same temperature,
the reaction was quenched with triethylamine followed by fil-
tration through Celite pad and washing of pad with ethyl ace-
tate. The combined solutions were washed with saturated
aqueous NaHCO3 and brine, dried over Na2SO4, and concen-
trated in vacuo. The residue was filtrated through Bio beads
SX-3 with elution of toluene/ethyl acetate (1:1) to give
Supplementary data associated with this article can be
found in the online version, at doi:10.1016/j.tet.2007.10.087.
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