Environmentally benign β-stereoselective glycosidations of glycosyl phosphites using a reusable heterogeneous solid acid, montmorillonite K-10

Article abstract of DOI:10.1016/j.carres.2004.11.025

Environmentally benign and stereoselective β-glycosidations of glycopyranosyl phosphites and alcohols using a reusable heterogeneous solid acid, montmorillonite K-10, as an activator have been developed. By these glycosidations, β-gluco-, 2-deoxy-β-gluco-

Full text of DOI:10.1016/j.carres.2004.11.025

Carbohydrate
RESEARCH
Carbohydrate Research 340 (2005) 337–353
Environmentally benign b-stereoselective glycosidations of glycosyl
phosphites using a reusable heterogeneous solid
acid, montmorillonite K-10q
Hideyuki Nagai, Kaname Sasaki, Shuichi Matsumura and Kazunobu Toshima*
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi,
Kohoku-ku, Yokohama 223-8522, Japan
Received 4 August 2004; accepted 17 November 2004
Available online 30 December 2004
Abstract—Environmentally benign and stereoselective b-glycosidations of glycopyranosyl phosphites and alcohols using a reusable
heterogeneous solid acid, montmorillonite K-10, as an activator have been developed. By these glycosidations, b-gluco-, 2-deoxy-b-
gluco-, and b-mannopyranosides were selectively produced in good to high yields.
ꢀ 2004 Elsevier Ltd. All rights reserved.
Keywords: Glycosidation; Glycosyl phosphite; Heterogeneous solid acid; Montmorillonite K-10
1. Introduction
(SO4/ZrO2) or Nafion-H as environmentally friendly
heterogeneous activators. Glycosyl phosphites have also
attracted considerable attention as effective glycosyl do-
nors.7–11 However, heterogeneous solid acid-mediated
glycosidation involving glycosyl phosphite has never
been reported. We report here the novel and environ-
mentally benign glycosidations of glycosyl phosphites
with alcohols, using a heterogeneous and reusable solid
acid, montmorillonite K-10, for the highly stereoselec-
tive syntheses of b-gluco-, 2-deoxy-b-gluco-, and b-man-
no-pyranosides (Fig. 1).12
Carbohydrates are a naturally abundant and renewable
feedstock. Various glycoconjugates and oligosacchar-
ides are found in many bioactive or functional mole-
cules. Such glycosubstances including, glycoconjugates
and oligosaccharides, continue to be a central focus of
research in chemistry, biology, and material science.1
One of the most important reactions of carbohydrates
is chemical glycosidation,2 for preparing both natural
and unnatural glycosides. Consequently, a highly effec-
tive, simple, and environmentally benign glycosidation
method is urgently needed in both academia and indus-
try. In this context, the ÔgreeningÕ of chemical glycosida-
tion could include the use of a heterogeneous and
reusable solid acid as an activator. In previous studies,
we have demonstrated several stereoselective O-glycosi-
dation methods using glycals,3 glycosyl fluorides,4 glyco-
syl sulfoxides,5 and 1-hydroxy sugars6 as glycosyl
donors, and montmorillonite K-10, sulfated zirconia
2. Results and discussion
2.1. b-Glucosidation
Stereoselective b-glucosidation13 is a very attractive goal
in the field of carbohydrate chemistry because of the
wide distribution of b-glucosides in nature. In this con-
text, Wong,8c Watanabe,9a and Hashimoto10a have inde-
pendently demonstrated the highly stereoselective 1,2-
trans-b-glucosidations of glucopyranosyl phosphites,
using a Lewis acid as a homogeneous promoter.
With these results in mind, we first examined the
q Taken in part from the Ph.D. Thesis of Hideyuki Nagai, Keio
University, 2004.
*
Corresponding author. Tel./fax: +81 45 566 1576; e-mail: toshima@
applc.keio.ac.jp
0008-6215/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2004.11.025

338
H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
Montmorillonite K-10
O
O
+
(BnO)n
R-OH
(BnO)n
O
OP(OEt)2
R
(β>>α)
Glycosyl donors
Glycosyl acceptors
BnO
BnO
Me
Me
O
HO
HO
HO
HO
Me
HO
BnO
OP(OEt)2
OBn
10
OMe
11
8
9
1
Me
BnO
R2O
R1O
O
O
O
BnO
Me
HO
O
BnO
BnO
OP(OEt)2
BnO
OP(OEt)2
OP(OEt)2
3: R1=Bn, R2=Bn
4: R1=Bn, R2=Bz
5: R1=Bz, R2=Bn
6: R1=Bz, R2=Bz
O
BnO
2
O
OMe
Me
12
13
Me
OBn
O
Ph
O
O
O
Me
Ph
O
BnO
HO
O
BnO
O
O
HO
BnO
7
BnO
BnO
HO
OMe
BnO
16
OMe
OMe
15
14
Figure 1. b-Stereoselective glycosidations of glycopyranosyl diethyl phosphites using a heterogeneous solid acid, montmorillonite K-10.
a
glycosidations of the totally benzylated glucopyranosyl
diethyl phosphite 110a (a/b = 73/27) and cyclohexylmeth-
anol (8), using several heterogeneous solid acids, such as
Nafion-H, sulfated zirconia (SO4/ZrO2), and montmo-
rillonite K-10. These heterogeneous solid acids are well
known as environmentally benign catalysts for organic
synthesis; they are easily handled because of their non-
volatile, noncorrosive, and odorless properties, and they
can be recovered from the reaction mixture by simple fil-
tration and then be reused. Neutralization of the reac-
tion mixture is not required after the reaction is
complete. Consequently, extraction of the product from
the reaction mixture by an organic solvent is not needed
in the work-up process. The results of such glycosida-
tion are summarized in Table 1. It was found, for the
first time, that the glucopyranosyl diethyl phosphite 1
was effectively activated by these heterogeneous solid
acids in CH2Cl2 under mild conditions, and underwent
smooth coupling with the alcohol 8 to give the corre-
sponding glucopyranosides 17 in high yield. Among
these, montmorillonite K-10 was found to be superior
to the other solid acids with respect to both the chemical
yield and b-stereoselectivity (entry 3 in Table 1). It is
noteworthy that the stereoselective tendency of the pres-
ent glycosidation is similar to those in WongÕs, Watan-
abeÕs, and HashimotoÕs glycosidations, all of which use
benzyl-protected glucopyranosyl phosphite and a homo-
geneous promoter. Our attention turned next to solvent
effects on this glycosidation using montmorillonite K-10
as the activator. The glycosidation of 1 and 8, using
montmorillonite K-10 in several solvents such as Et2O,
MeCN, and PhMe was tested and compared to that in
Table 1. Glycosidations of 1 and 8 by several solid acids in CH2Cl2
solid acid
+
1
8
17
25 ºC, 15 h
Entry Solid acid (wt %) Solvent
(0.1 M)
Yieldb (%) a/b Ratioc
1
2
3
Nafion-H (100)
SO4/ZrO2 (100)
Montmorillonite
K-10 (100)
CH2Cl2 83
CH2Cl2 73
CH2Cl2 90
28/72
55/45
27/73
a All reactions were carried out using of 2.0 equiv of 8 to 1.
b Isolated yields after purification by column chromatography.
c a/b Ratios were determined by HPLC analysis (column, CrestPak
C18Sꢂ, 4.6 · 150 mm; eluent, 10% H2O in MeCN; flow rate, 1.0 mL/
min, 40 ꢁC; detection, UV 250 nm).
CH2Cl2 (Table 2). The highest yield was obtained in
CH2Cl2 (entry 3 in Table 1), while the highest b-stereose-
lectivity was observed in MeCN (entry 2 in Table 2). The
glycosidation proceeded effectively, even at 0 ꢁC for
30 min in both cases, and the b-stereoselectivity gradu-
ally increased as the reaction temperature decreased (en-
tries 5 and 8 in Table 2). The addition of 100 wt %
montmorillonite K-10 to the glycosyl donor 1 gave the
best results, and the use of a smaller or larger amount
of montmorillonite K-10 was less effective in both cases
(entries 4–9 in Table 2). When larger amounts of mont-
morillonite K-10 were used, considerable amounts of the
corresponding 1-OH sugar were produced because of
the hydrolysis of 1 by water originally contained in the
montmorillonite K-10. We further examined the glycos-
idations of 1 and 8 using 100 wt % montmorillonite

H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
Table 2. Glycosidations of 1 and 8 by montmorillonite K-10 under various conditionsa
339
Montmorillonite K-10
+
8
17
Time (h)
1
Entry
wt % of K-10
Solvent (0.1 M)
Temp (ꢁC)
Yieldb (%)
a/b Ratioc
1
100
100
100
50
Et2O
MeCN
PhMe
25
25
25
0
15
15
15
62
75
80
89
93
92
83
86
84
82
94
87
56/44
18/82
26/74
23/77
23/77
24/76
11/89
11/89
14/86
6/94
2
3
4
CH2Cl2
CH2Cl2
CH2Cl2
MeCN
MeCN
MeCN
CH2Cl2–MeCN (5:1)d
CH2Cl2–MeCN (10:1)d
CH2Cl2–MeCN (15:1)d
0.5
5
100
200
50
0
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
6
0
7
0
8
100
200
100
100
100
0
9
0
10
11
12
ꢀ20
ꢀ20
ꢀ20
6/94
10/90
a All reactions were carried out using 2.0 equiv of 8 to 1.
b Isolated yields after purification by column chromatography.
c a/b Ratios were determined by HPLC analysis (column, CrestPak C18Sꢂ, 4.6 · 150 mm; eluent, 10% H2O in MeCN; flow rate, 1.0 mL/min, 40 ꢁC;
detection, UV 250 nm).
d 0.05 M solvent was used.
K-10 in mixed solvents of CH2Cl2 and MeCN. After
several attempts, we finally found that the glycosidation
of 1 and 8 using 100 wt % montmorillonite K-10 in 10:1
CH2Cl2–MeCN (0.05 M for 1) at ꢀ20 ꢁC for 30 min was
the best combination, affording the corresponding
glucopyranosides 17 in 94% yield with 6:94 a/b-stereose-
lectivity (entry 11 in Table 2). With the optimized condi-
tions in hand, the glycosidations using other primary
and secondary alcohols (9–14), and including sugar
derivatives 12,14 13,15 and 1416 were next carried out
to enhance the synthetic utility of the procedure. Based
on the results (summarized in Table 3), the glycosida-
tions of 1 and 9–11 using 100 wt % montmorillonite
K-10 in 10:1 CH2Cl2–MeCN at ꢀ20 ꢁC for 30 min, as
well as that of 8, proceeded effectively to give the corre-
Table 4. Recycling of montmorillonite K-10 in glycosidation of 1 and
8
Recycling number
0
1st
2nd
3rd
Yield (%)
a/b Ratio
94
6/94
90
5/95
86
5/95
70
7/93
sponding b-glucopyranosides 18b–20b in high yields (en-
tries 2–4 in Table 3). When the sugar derivatives 12–14
were employed as glycosyl acceptors, a longer reaction
time (2 h) was required, and 3.0 equiv of the glycosyl
acceptor was needed for such low-reactive glycosyl
acceptors as 13 to obtain good yields of the correspond-
ing b-glucopyranosides 21b–23b (entries 5–7 in Table 3).
It was confirmed that the glycosidic bond at the ano-
meric position of the glycoside obtained was not epimer-
ized under the glycosidation conditions. Therefore, the
predominant b-stereoselectivity must arise from kinetic
control. Such acid-sensitive protecting groups such as
benzylidene and isopropylidene acetals were not cleaved
under these conditions. Finally, we tested the solid acid,
montmorillonite K-10, for recycling in the glycosidation
reaction. After filtration followed by washing with chlo-
roform and methanol and drying at 100 ꢁC/1 mmHg for
12 h, the recycled montmorillonite K-10 was reused in
the glycosidation of 1 and 8 for at least three times
and showed good to high yields and high b-stereoselec-
tivities, as described in Table 4. No further addition of
the fresh montmorillonite K-10 was needed to perform
the glycosidation repeatedly.
Table 3. b-Stereoselective glycosidations of 1 and several alcoholsa
Montmorillonite K-10
(100 wt%)
+
17-23
1
8-14
10:1 CH2Cl2-MeCN
-20 ºC
Entry Alcohola Time (h) Product Yieldb (%) a/b Ratioc
1
2
3
4
5
6
7
8
9
0.5
0.5
0.5
0.5
2
17
18
19
20
21
22
23
94
88
88
86
77
74
73
6/94
6/94
7/93
8/92
7/93
16/84
13/87
10
11
12
13d
14
2
2
a All reactions were carried out using 2.0 equiv of the alcohol to 1.
b Isolated yields after purification by column chromatography.
c a/b Ratios were determined by HPLC analysis (column, CrestPak
C18Sꢂ, 4.6 · 150 mm; eluent, 10% H2O in MeCN for entries 1–4 and
6, 12.5% H2O in MeCN for entry 5; flow rate, 1.0 mL/min, 40 ꢁC;
detection, UV 250 nm).
2.2. b-2-Deoxyglycosidation
Deoxy sugars frequently feature in the glycosidic com-
ponents of bioactive substances.17,18 Among them,
d 3.0 equiv of alcohol was used.

340
H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
2-deoxyglycosides, including 2,6-dideoxyglycosides, are
some of the most common and important, and are
found in many biologically interesting natural products,
especially in antitumor antibiotics. However, direct and
stereoselective b-glycosidation of a 2-deoxy sugar is
quite difficult because of the anomeric effect and the lack
of stereodirecting anchimeric assistance from the C-2
position.2c,19 Therefore, the development of direct and
stereoselective b-glycosidations of 2-deoxy sugar20,21 in
an environmentally compatible manner is of particular
interest. In our studies just mentioned, we have observed
b-stereoselective glycosidation of the benzyl-protected
glucopyranosyl diethyl phosphite 1 with several alco-
hols, using montmorillonite K-10 with a nonparticipat-
ing group. Hashimoto and co-workers reported an
efficient b-stereoselective glycosidation of 2-deoxygly-
copyranosyl diethyl phosphite using a homogeneous
promoter, trimethysilyl trifluoromethanesulfonate (Me3-
SiOTf).10b Therefore, based on these results, we next
examined the glycosidations of the totally benzylated
2-deoxyglucopyranosyl diethyl phosphite 210b and the
sugar derivative alcohol 12, using montmorillonite K-
10 under various conditions. The results are summarized
in Table 5. Unfortunately, we found that glycosidation
of 2 (a/b = 80/20) and 12, under conditions similar to
the optimized conditions for the benzylated glucopyr-
anosyl diethyl phosphite 1, gave the 2-deoxyglucopyr-
anosides 24 in low yield and with low stereoselectivity
(entry 1 in Table 5). However, both the chemical yield
and stereoselectivity increased as the reaction tempera-
ture decreased, and when the glycosidation was per-
formed at low temperature, ꢀ78 ꢁC, a better chemical
yield and b-stereoselectivity were obtained (entry 2 in
Table 5). In addition, it was found that the glycosida-
tions of 2 and 12 in Et2O at ꢀ78 ꢁC proceeded effectively
to afford 24 in high yield (87%) with good b-stereoselec-
tivity (a/b = 19/81) (entry 7 in Table 5). Diethyl ether
was shown to be superior to such other solvents as
CH2Cl2, EtCN, PhMe, and THF (entries 3–7 in Table
5) with respect to both the chemical yield and unusual
b-stereoselectivity. Moreover, it was confirmed that the
chemical yield and b-stereoselectivity were highly depen-
dent on the amount of montmorillonite K-10 and the
reaction temperature. The highest chemical yield and
b-stereoselectivity were achieved when 100 wt % mont-
morillonite K-10 was used in Et2O at ꢀ78 ꢁC for 1 h (en-
tries 7–12 in Table 5). The optimized conditions for
selectively obtaining the 2-deoxy-b-glucopyranoside dif-
fered significantly from that for the previously men-
tioned b-stereoselective glucosidation. This difference
came from the higher reactivity of the 2-deoxyglycosyl
donor 2 as compared to that of the glucosyl donor 1.
With these favorable new results, next our attention
turned to the glycosidations of a typical 2,6-dideoxy su-
gar, olivose, because b-olivosides are very common and
important 2,6-dideoxyglycosides related to antitumor
antibiotics.17,18 Therefore, we examined the glycosida-
tion with 12 of the olivosyl diethyl phosphites 3 (a/
b = 86/14), 4 (a/b = 72/28), 5 (a/b = 89/11), and 6 (a/
b = 79/21), which have different protecting groups at
the C-3 and C-4. The results are outlined in Table 6.
In this case, it was found that the chemical yield and ste-
reoselectivity were highly dependent on the protecting
groups at C-3 and 4 of the donors, and the C-4 acyl pro-
tecting group significantly assisted the b-stereoselectivity
by the participating effect, as shown in Figure 2.5,22
Thus, the glycosidations of 4 and 12 using 100 wt %
montmorillonite K-10 in Et2O at ꢀ78 ꢁC for 1 h effec-
tively gave the corresponding olivosides 26 in 92% yield
with 10:90 a/b-stereoselectivity (entry 2 in Table 6).
Armed with these results, the glycosidations of 2 and 4
Table 5. Glycosidations of 2 and 12 by montmorillonite K-10 under
various conditionsa
Montmorillonite K-10
+
2
12
24
Entry Wt % Solvent
of K-10 (0.1 M)
Temp Yieldb a/b
(ꢁC)
(%)
Ratioc
1
100
100
100
100
100
100
100
200
50
CH2Cl2–MeCN (10:1)d ꢀ20
58
78
87
81
69
84
87
82
80
63
80
77
43/57
26/74
23/77
32/68
25/75
47/53
19/81
24/76
21/79
21/79
31/69
44/56
Table 6. Glycosidations of 3–6 and 12 by montmorillonite K-10a
2
CH2Cl2–MeCN (10:1)d ꢀ78
Montmorillonite K-10
(100 wt%)
3
CH2Cl2
EtCN
PhMe
THF
Et2O
Et2O
Et2O
Et2O
Et2O
Et2O
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ78
ꢀ50
ꢀ20
4
+
3-6
12
25-28
5
Et2O
6
-78 ºC, 1 h
7
Entry
Donor
Product
Yieldb (%)
a/b Ratioc
8
9
1
2
3
4
3
4
5
6
25
26
27
28
76
92
72
68
20/80
10/90
22/78
16/84
10
11
12
20
100
100
a All reactions were carried out using 2.0 equiv of 12 to 2.
b Isolated yields after purification by column chromatography.
a All reactions were carried out using 2.0 equiv of 12 to the glycosyl
donors 3–6.
c a/b Ratios were determined by HPLC analysis (column, CrestPak
C18Sꢂ, 4.6 · 150 mm; eluent, 10% H2O in MeCN; flow rate, 0.5 mL/
min, 40 ꢁC; detection, UV 250 nm).
b Isolated yields after purification by column chromatography.
c a/b Ratios were determined by HPLC analysis (column, CrestPak
C18Sꢂ, 4.6 · 150 mm; eluent, 10% H2O in MeCN; flow rate, 0.5 mL/
min, 40 ꢁC; detection, UV 250 nm).
d 0.05 M solvent was used.

H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
341
H
Me
BnO
+
O
Me
R-OH
O
O
BzO
BnO
R
4
OR
β
Montmorillonite K-10
O
O
Figure 2. C-4 participation in the glycosidation of 4.
lonite K-10 as described in the glycosidation of 1, the
recovered montmorillonite K-10 could be reused for at
least three times and showed high yields and good b-ste-
reoselectivities, as described in Table 8.
Table 7. b-Stereoselective glycosidations of 2 and 4 with and several
alcoholsa
Montmorillonite K-10
(100 wt%)
+
2 or 4
8-13, 15
24, 26, 29-40
Et2O
-78 ºC, 1 h
2.3. b-Mannosidation
Entry Donor Alcohol Product Yieldb (%) a/b Ratioc
Since b-mannopyranosides feature in many natural bio-
active substances, such as asparagine-linked glycopro-
teins and certain antibiotics, the stereocontrolled
formation of b-mannopyranosides is of considerable
importance.24 The stereoselective and direct construc-
tion of b-mannopyranosides is particularly difficult, be-
cause the axial b-hydroxy group at C-2 and the
anomeric effect block access to the b face. A direct
and stereoselective construction of b-mannopyranosidic
linkages25,26 in a practical and environmentally friendly
manner is thus of particular interest. b-Stereoselective
mannosidation using mannopyranosyl diethyl phosphite
and Me3SiOTf was very recently announced by Hashim-
otoÕs group.10e As another challenging extension of our
studies, we next examined the glycosidation of 2,3-di-O-
benzyl-4,6-O-benzylidene-a-D-mannopyranosyl diethyl
phosphite (7)10e and the sugar alcohol 12, using mont-
morillonite K-10 as a heterogeneous activator,27 under
various conditions. These results are summarized in
Table 9. The glycosidation of 7 and 12 proceeded smoothly
in CH2Cl2 to give the disaccharides 41 in high yield with
good b-stereoselectivity. The other solvents examined
such as PhMe, Et2O, and MeCN were less effective than
CH2Cl2 with respect to both the chemical yield and b-
stereoselectivity (entries 1–4 in Table 9). Lower reaction
temperatures, <ꢀ30 ꢁC, significantly decreased the
chemical yield, while the stereoselectivity was not chan-
ged (entries 5 and 6 in Table 9). The use of 200 wt %
montmorillonite K-10 increased the chemical yield, with
good b-stereoselectivity (entries 5, 7–9 in Table 9). Thus,
the glycosidation of 7 and 12 was best effected by using
200 wt % montmorillonite K-10 in CH2Cl2 at ꢀ10 ꢁC
for 1 h, giving 41 in 93% yield with a/b ratio of 15/85.
The optimized conditions for obtaining the b-manno-
pyranoside stereoselectively differed significantly from
those for the previously mentioned b-stereoselective gly-
cosidations of glucopyranosyl and 2-deoxyglucopyrano-
syl diethyl phosphites 1 and 2. The chemical yields in the
glycosidations of 7 and 12, using a homogeneous Lewis
1
2
12
8
24
29
30
31
32
33
34
26
35
36
37
38
39
40
87
93
94
97
96
88
70
92
86
90
95
86
89
82
19/81
17/83
14/86
22/78
23/77
21/79
29/71
10/90
14/86
10/90
19/81
17/83
17/83
15/85
2
3
9
4
10
11
13
15
12
8
5
6
7
8
4
9
10
11
12
13
14
9
10
11
13
15
a All reactions were carried out using 2.0 equiv of the alcohol to 2 or 4.
b Isolated yields after purification by column chromatography.
c a/b Ratios were determined by HPLC analysis (column, CrestPak
C18Sꢂ, 4.6 · 150 mm; eluent, 10% H2O in MeCN; flow rate, 0.5 mL/
min, 40 ꢁC; detection, UV 250 nm).
using other primary and secondary alcohols (8–11, 13,
and 15)23 were next examined. The results summarized
in Table 7 show that the glycosidations of 2 and 4 with
8–11, 13, and 15, using 100 wt % montmorillonite K-10
in Et2O at ꢀ78 ꢁC for 1 h, as well as that of 12, pro-
ceeded effectively to give the corresponding 2-deoxy-b-
glucopyranosides 29b–34b and b-olivosides 35b–40b,
respectively, in good to high yields and with good stereo-
selectivities. Although it is well known that epimeriza-
tion of 2-deoxyglycosides occurs readily under strong
acidic conditions, no epimerization of the glycosidic
bond was observed during the present glycosidation.
We examined the recycling of the activator in the glycos-
idations of 2 and 8. After treating the used montmoril-
Table 8. Recycling of montmorillonite K-10 in glycosidation of 2 and
8
Recycling number
0
1st
2nd
3rd
Yield (%)
a/b Ratio
93
17/83
89
17/83
89
17/83
87
17/83

342
H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
Table 9. Glycosidations of 7 and 12 by montmorillonite K-10 under various conditionsa
Montmorillonite K-10
+
7
12
41
Entry
Activator
Amount of activator
Solvent (0.1 M)
Temp (ꢁC)
Time (h)
Yieldb (%)
a/b Ratioc
1
Montmorillonite K-10
Montmorillonite K-10
Montmorillonite K-10
Montmorillonite K-10
Montmorillonite K-10
Montmorillonite K-10
Montmorillonite K-10
Montmorillonite K-10
Montmorillonite K-10
Me3SiOTf
150 wt %
150 wt %
150 wt %
150 wt %
100 wt %
100 wt %
50 wt %
CH2Cl2
PhMe
Et2O
0
0
1
1
1
1
1
1
1
1
1
1
1
89
85
74
12
84
74
61
91
93
50
60
16/84
38/62
37/63
42/58
16/84
17/83
19/81
16/84
15/85
17/83
18/82
2
3
0
4
MeCN
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
0
5
ꢀ10
ꢀ30
ꢀ10
ꢀ10
ꢀ10
ꢀ10
ꢀ10
6
7
8
150 wt %
200 wt %
0.3 mol %
0.3 mol %
9
10
11
TfOH
a All reactions were carried out using 2.0 equiv of 12 to 7.
b Isolated yields after purification by column chromatography.
c a/b Ratios were determined by 300 MHz 1H NMR analysis.
Table 10. b-Stereoselective glycosidations of 7 and several alcoholsa
acid, Me3SiOTf, and a homogeneous protic acid, TfOH,
under similar conditions were much lower than that with
montmorillonite K-10 because of partial hydrolysis28 of
the benzylidene acetal group of 7 (entries 10 and 11 in
Table 9). Moreover, although the mannopyranosyl tri-
flate, which is the key intermediate for obtaining high
b-stereoselectivity in CrichÕs method,26 was not present
in this case, the 4,6-O-benzylidene functionality of 7
was found to be very helpful29 for achieving good b-ste-
reoselectivity. Indeed, a modest a/b ratio of 31/69 was
observed in the glycosidation of 2,3,4,6-tetra-O-benzyl-
a-D-mannopyranosyl diethyl phosphite (42) and 12 un-
der similar conditions (Fig. 3). These results strongly
suggest that the montmorillonite K-10 anion coordinate
with the oxonium intermediate came from 42. With
these favorable results, our attention then turned to
the scope and limitation of this glycosidation reaction.
Glycosidations of 7 with other primary and secondary
alcohols 8–11, 13, and 16 were next carried out. From
the results summarized in Table 10, it is clear glycosida-
tions of 8–11, 13, and 1630 using 200 wt % montmoril-
lonite K-10 in CH2Cl2 at ꢀ10 ꢁC for 1 h, as well as 12,
produces the corresponding b-mannopyranosides 44b–
49b in good to high yields with good b-stereoselectivi-
ties. Furthermore, the acid-sensitive isopropylidene ace-
tal group, is not cleaved under these conditions. The
montmorillonite K-10 recovered by washing followed
by drying could be reused for at least three times, and
Montmorillonite K-10
(200 wt%)
+
7
8-13, 16
41, 44-49
CH2Cl2
-10 ºC, 1 h
Entry
Alcohola
Product
Yield (%)b
a/b Ratioc
1
2
3
4
5
6
7
12
8
41
44
45
46
47
48
49
93
92
84
85
86
92
78
15/85
11/89
13/87
12/88
10/90
15/85
13/87
9
10
11
13
16
a All reactions were carried out using 2.0 equiv of the alcohol to 7.
b Isolated yields after purification by column chromatography.
c a/b Ratios were determined by 300 MHz 1H NMR analysis.
Table 11. Recycling of montmorillonite K-10 in glycosidation of 7 and
8
Recycling number
0
1st
2nd
3rd
Yield (%)
a/b Ratio
92
11/89
91
12/88
86
10/90
82
9/91
showed similar high yields and good stereoselectivities
in the glycosidations of 7 and 8 (Table 11).
BnO
BnO
OBn
O
BnO
BnO
OBn
O
Montmorillonite K-10
+
12
BnO
O
BnO
O
CH2Cl2
-10 ˚C, 1 h
BnO
BnO
OP(OEt)2
42
BnO
43
88%
α/β=31/69
OMe
Figure 3. Glycosidation of mannopyranosyl diethyl phosphite 42 and 2.

H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
343
3. Conclusion
4.2.1. Cyclohexylmethyl 2,3,4,6-tetra-O-benzyl-a-D-
glucopyranoside (17a). Colorless syrup, Rf 0.35 (4:1 n-
hexane–EtOAc); ½aꢁ +43.1 (c 1.03, CHCl3); H NMR
27
D
1
We have presented a stereoselective strategy for the di-
rect syntheses of b-gluco-, 2-deoxy-b-gluco-, and b-
mannopyranosides from appropriate glycopyranosyl
diethyl phosphites and alcohols, using a reusable heter-
ogeneous solid acid, montomorillonite K-10. The re-
sults, showing a simple protocol and stereoselectivity,
should stimulate further research on heterogeneous solid
acids in glycosidation reactions. The present protocols
should find wide application for the synthesis of biolog-
ically important natural products.
d 0.83–1.02 (2H, m), 1.07–1.35 (3H, m), 1.58–1.90 (6H,
m), 3.19 (1H, dd, J 9.6 and 6.0 Hz), 3.42 (1H, dd, J
9.6 and 7.2 Hz), 3.55 (1H, dd, J 9.6 and 3.6 Hz), 3.58–
3.82 (4H, m), 3.97 (1H, dd, J 9.0 and 9.0 Hz), 4.47
(2H, d, J 11.6 Hz), 4.61 (1H, d, J 11.6 Hz), 4.63 (1H,
d, J 12.4 Hz), 4.73 (1H, d, J 3.6 Hz), 4.77 (1H, d, J
12.4 Hz), 4.81 (1H, d, J 11.0 Hz), 4.82 (1H, d, J
10.4 Hz), 5.00 (1H, d, J 11.0 Hz), 7.10–7.16 (2H, m),
7.22–7.40 (18H, m). Anal. Calcd for C41H48O6: C,
77.33; H, 7.60. Found: C, 77.31; H, 7.55.
4. Experimental
4.2.2. Cyclohexylmethyl 2,3,4,6-tetra-O-benzyl-b-D-
glucopyranoside (17b). White solid, mp 97.0–
26
D
4.1. General methods
98.5 ꢁC; Rf 0.40 (4:1 n-hexane–EtOAc); ½aꢁ +4.5 (c
1
1.05, CHCl3); H NMR d 1.11–1.34 (3H, m), 1.58–1.92
Melting points were determined on a micro hot-stage
Yanako MP-S3 and were uncorrected. Optical rotations
were measured on a Jasco DIP-360 photoelectric polar-
(6H, m), 3.32 (1H, dd, J 9.6 and 7.0 Hz), 3.40–
3.49 (2H, m), 3.52–3.78 (4H, m), 3.79 (1H, dd, J 9.6
and 6.0 Hz), 4.37 (1H, d, J 7.4 Hz), 4.52 (1H, d, J
11.6 Hz), 4.56 (1H, d, J 10.4 Hz), 4.63 (1H, d, J 11.6
Hz), 4.72 (1H, d, J 10.8 Hz), 4.78 (1H, d, J 10.8 Hz),
4.82 (1H, d, J 10.4 Hz), 4.92 (1H, d, J 10.8 Hz), 4.97
(1H, d, J 10.8 Hz), 7.12–7.18 (2H, m), 7.22–7.38 (18H,
m). Anal. Calcd for C41H48O6: C, 77.33; H, 7.60. Found:
C, 77.20; H, 7.51.
1
imeter in chloroform unless otherwise noted. H NMR
spectra were recorded on a Jeol GSX 270 (270 MHz)
or a Lambda 300 (300 MHz) spectrometer in CDCl3
using Me4Si as the internal standard, unless otherwise
noted. Thin-layer and column chromatography was per-
formed on Merck 60F-254 (0.25 mm) TLC plates and
Kanto Chemical Co., Inc Silica Gel 60 N (spherical,
neutral), respectively. Nafion-H was purchased from
Wako Pure Chemical Industries, Ltd. as Nafionꢂ NR-
50 and was dried at 25 ꢁC/1 mmHg for 2 h before using.
SO4/ZrO2 was purchased from Wako Pure Chemical
Industries, Ltd. and dried at 200 ꢁC/1 mmHg for 12 h
before using. Montmorillonite K-10 was purchased
from Aldrich Chemical Company, Inc. and dried at
200 ꢁC/1 mmHg for 12 h before using. Air- and/or mois-
ture-sensitive reactions were carried out under an atmo-
sphere of argon with oven-dried glassware. In general,
organic solvents were purified and dried by appropriate
procedures, and evaporations and concentrations were
carried out under diminished pressure below 30 ꢁC, un-
less otherwise noted.
4.2.3. n-Octyl 2,3,4,6-tetra-O-benzyl-a-D-glucopyrano-
side (18a). Colorless syrup, Rf 0.45 (6/1 n-hexane–
28
D
1
EtOAc); ½aꢁ +39.5 (c 1.38, CHCl3); H NMR d 0.82–
0.93 (3H, m), 1.18–1.40 (10H, m), 1.50–1.68 (2H, m),
3.41 (1H, dt, J 10.4 and 6.4 Hz), 3.55 (1H, dd, J 9.2
and 3.6 Hz), 3.55–3.68 (1H, m), 3.62 (1H, dd, J 10.4
and 3.6 Hz), 3.63 (1H, dd, J 9.2 and 4.8 Hz), 3.72 (1H,
dd, J 10.4 and 4.8 Hz), 3.78 (1H, ddd, J 10.4, 4.8, and
3.6 Hz), 3.98 (1H, dd, J 9.2 and 9.2 Hz), 4.47 (2H, d, J
11.0 Hz), 4.61 (1H, d, J 11.0 Hz), 4.64 (1H, d, J 11.0
Hz), 4.75 (1H, d, J 3.2 Hz), 4.78 (1H, d, J 11.0 Hz),
4.81 (1H, d, J 11.0 Hz), 4.82 (1H, d, J 11.0 Hz), 4.89
(1H, d, J 11.0 Hz), 7.09–7.18 (2H, m), 7.20–7.40 (18H,
m). Anal. Calcd for C42H52O6: C, 77.27; H, 8.03. Found:
C, 77.29; H, 7.84.
4.2. Glycosidation protocol for the preparation of the b-
glucopyranosides
4.2.4. n-Octyl 2,3,4,6-tetra-O-benzyl-b-D-glucopyrano-
side (18b). White solid, mp 32.2–33.0 ꢁC; Rf 0.50 (6:1
28
To a stirred solution of 2,3,4,6-tetra-O-benzyl-D-gluco-
pyranosyl diethyl phosphite (1, a/b = 73/27, 0.1 mmol)
and an alcohol (0.2 mmol) in dry 10:1 CH2Cl2–MeCN
(2 mL) was added montmorillonite K-10 (100 wt % to
the glycosyl donor 1). After stirring at ꢀ20 ꢁC for
30 min, the mixture was filtered and the filtrate was con-
centrated in vacuo. Purification of the residue by flash
column chromatography gave the corresponding gluco-
pyranosides, which contained predominately the b
anomers.
n-hexane–EtOAc); ½aꢁ
+5.8 (c 1.38, CHCl3); 1H
D
NMR d 0.82–0.93 (3H, m), 1.19–1.46 (10H, m), 1.58–
1.74 (2H, m), 3.44 (1H, dd, J 9.0 and 7.6 Hz), 3.42–
3.55 (2H, m), 3.57 (1H, dd, J 9.0 and 9.0 Hz),
3.63–3.71 (1H, m), 3.64 (1H, dd, J 9.0 and 9.0 Hz),
3.75 (1H, dd, J 10.4 and 2.2 Hz), 3.96 (1H, dt, J 9.6
and 6.6 Hz), 4.39 (1H, d, J 7.6 Hz), 4.52 (1H, d, J 11.0
Hz), 4.56 (1H, d, J 12.4 Hz), 4.62 (1H, d, J 12.4 Hz),
4.72 (1H, d, J 11.0 Hz), 4.78 (1H, d, J 10.2 Hz), 4.82
(1H, d, J 10.2 Hz), 4.93 (1H, d, J 11.0 Hz), 4.96 (1H,

344
H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
d, J 11.0 Hz), 7.13–7.18 (2H, m), 7.22–7.39 (18H, m).
Anal. Calcd for C42H52O6: C, 77.27; H, 8.03. Found:
C, 77.32; H, 7.96.
(1H, dd, J 8.8 and 7.6 Hz), 3.65 (1H, dd, J 10.4 and
4.2 Hz), 3.74 (1H, dd, J 10.4 and 1.6 Hz), 4.02 (1H, sep-
tet, J 6.0 Hz), 4.46 (1H, d, J 7.6 Hz), 4.53 (1H, d, J
10.8 Hz), 4.56 (1H, d, J 11.6 Hz), 4.61 (1H, d, J 11.6
Hz), 4.70 (1H, d, J 10.8 Hz), 4.78 (1H, d, J 10.8 Hz),
4.82 (1H, d, J 10.8 Hz), 4.92 (1H, d, J 10.8 Hz), 4.97
(1H, d, J 10.8 Hz), 7.13–7.19 (2H, m), 7.23–7.39 (18H,
m). Anal. Calcd for C37H42O6: C, 76.26; H, 7.26. Found:
C, 76.25; H, 7.11.
4.2.5. Cyclohexyl 2,3,4,6-tetra-O-benzyl-a-D-glucopyr-
anoside (19a). Colorless syrup, Rf 0.64 (60:1 chloro-
28
D
1
form–EtOAc); ½aꢁ +56.0 (c 0.74, CHCl3); H NMR d
1.10–1.62 (6H, m), 1.66–1.96 (4H, m), 3.48–3.69 (1H,
m), 3.55 (1H, dd, J 9.6 and 3.6 Hz), 3.62 (1H, dd, J
11.2 and 2.0 Hz), 3.63 (1H, dd, J 9.8 and 9.2 Hz), 3.74
(1H, dd, J 11.2 and 3.6 Hz), 3.88 (1H, ddd, J 9.8, 3.6
and 2.0 Hz), 4.00 (1H, dd, J 9.2 and 9.2 Hz), 4.47 (2H,
d, J 11.2 Hz), 4.62 (1H, d, J 11.2 Hz), 4.65 (1H, d, J
10.6 Hz), 4.75 (1H, d, J 11.2 Hz), 4.80 (1H, d, J
10.6 Hz), 4.82 (1H, d, J 10.6 Hz), 4.95 (1H, d, J
3.6 Hz), 5.00 (1H, d, J 10.6 Hz), 7.09–7.16 (2H, m),
7.20–7.38 (18H, m). Anal. Calcd for C40H46O6: C,
77.14; H, 7.44. Found: C, 76.97; H, 7.21.
4.2.9. Methyl 2,3,4-tri-O-benzyl-6-O-(2,3,4,6-tetra-O-
benzyl-a-D-glucopyranosyl)-a-D-glucopyranoside (21a).
White solid, mp 101.8–102.8 ꢁC;Rf 0.35 (3:1 n-hexane–
28
1
EtOAc); ½aꢁ +145 (c 0.71, CHCl3); H NMR d 3.35
D
(3H, s), 3.44 (1H, dd, J 9.6 and 3.6 Hz), 3.49–3.86
(9H, m), 3.90–4.03 (2H, m), 4.37–4.48 (2H, m),
4.53–4.67 (5H, m), 4.55 (1H, d, J 3.4 Hz), 4.71 (1H, d,
J 12.0 Hz), 4.77 (1H, d, J 10.6 Hz), 4.81 (1H, d, J 10.6
Hz), 4.82 (1H, d, J 11.4 Hz), 4.92 (1H, d, J 11.4 Hz),
4.93 (1H, d, J 10.6 Hz), 4.96 (1H, d, J 11.4 Hz),
4.98 (1H, d, J 3.8 Hz), 7.08–7.13 (2H, m), 7.20–7.36
(33H, m). Anal. Calcd for C62H66O11: C, 75.43; H,
6.74. Found: C, 75.34; H, 6.49.
4.2.6. Cyclohexyl 2,3,4,6-tetra-O-benzyl-b-D-glucopyr-
anoside (19b). White solid, mp 103.5–105.0 ꢁC; Rf
28
0.48 (60:1 chloroform–EtOAc); ½aꢁ +9.2 (c 1.01,
D
1
CHCl3); H NMR d 1.16–1.62 (6H, m), 1.68–1.84 (2H,
m), 1.88–2.08 (2H, m), 3.44 (1H, dd, J 8.2 and
8.2 Hz), 3.45 (1H, ddd, J 9.2, 5.0, and 2.0 Hz),
3.59–3.79 (2H, m), 3.65 (1H, dd, J 8.2 and 7.2 Hz), 3.74
(1H, dd, J 9.2 and 2.0 Hz), 4.50 (1H, d, J 7.2 Hz), 4.53
(1H, d, J 11.0 Hz), 4.56 (1H, d, J 12.0 Hz), 4.61 (1H,
d, J 12.0 Hz), 4.71 (1H, d, J 11.0 Hz), 4.77 (1H, d, J
11.0 Hz), 4.82 (1H, d, J 11.0 Hz), 4.92 (1H, d, J
11.0 Hz), 4.99 (1H, d, J 11.0 Hz), 7.14–7.19 (2H, m),
7.22–7.38 (18H, m). Anal. Calcd for C40H46O6: C,
77.14; H, 7.44. Found: C, 77.18; H, 7.26.
4.2.10. Methyl 2,3,4-tri-O-benzyl-6-O-(2,3,4,6-tetra-O-
benzyl-b-D-glucopyranosyl)-a-D-glucopyranoside (21b).
White solid, mp 136.5–138.0 ꢁC; Rf 0.35 (3:1 n-hex-
27
1
ane–EtOAc); ½aꢁ +19.5 (c 1.31, CHCl3); H NMR d
D
3.32 (3H, s), 3.38–3.75 (9H, m), 3.82 (1H, dd, J 10.6
and 3.6 Hz), 3.99 (1H, dd, J 9.4 and 9.4 Hz), 4.18 (1H,
dd, J 10.6 and 2.0 Hz), 4.34 (1H, d, J 8.0 Hz),
4.47–4.60 (5H, m), 4.61 (1H, d, J 3.6 Hz), 4.65 (1H, d,
J 12.0 Hz), 4.71 (1H, d, J 11.0 Hz), 4.74–4.82 (3H, m)
4.80 (1H, d, J 10.6 Hz), 4.90 (1H, d, J 11.0 Hz), 4.96
(1H, d, J 11.0 Hz), 4.97 (1H, d, J 11.0 Hz), 7.13–7.37
(35H, m). Anal. Calcd for C62H66O11: C, 75.43; H,
6.74. Found: C, 75.36; H, 6.49.
4.2.7. Isopropyl 2,3,4,6-tetra-O-benzyl-a-D-glucopyrano-
side (20a). Colorless syrup, Rf 0.60 (60:1 chloroform–
28
D
1
EtOAc); ½aꢁ +38.4 (c 1.32, CHCl3); H NMR d 1.11
and 1.15 (each 3H, each d, J 6.0 Hz), 3.48 (1H,
dd, J 9.2 and 3.2 Hz), 3.54 (1H, dd, J 10.4 and
2.0 Hz), 3.57 (1H, dd, J 9.8 and 9.2 Hz), 3.67 (1H, dd,
J 10.4 and 3.2 Hz), 3.77 (1H, ddd, J 9.8, 3.2, and
2.0 Hz), 3.82 (1H, septet, J 6.0 Hz), 3.92 (1H, dd, J 9.2
and 9.2 Hz), 4.39 (2H, d, J 12.0 Hz), 4.54 (1H, d, J 12.0
Hz), 4.58 (1H, d, J 11.2 Hz), 4.71 (1H, d, J 12.0 Hz),
4.74 (1H, d, J 11.2 Hz), 4.76 (1H, d, J 11.2 Hz),
4.80 (1H, d, J 3.2 Hz), 4.93 (1H, d, J 10.6 Hz),
7.02–7.08 (2H, m), 7.14–7.33 (18H, m). Anal. Calcd
for C37H42O6: C, 76.26; H, 7.26. Found: C, 76.35; H,
6.99.
4.2.11. Methyl 4-O-(2,3,4,6-tetra-O-benzyl-a-D-gluco-
pyranosyl)-2,3-O-isopropylidene-a-L-rhamnopyranoside
(22a). Colorless syrup, Rf 0.40 (3:1 n-hexane–EtOAc);
28
1
½aꢁ +37.7 (c 0.77, CHCl3); H NMR d 1.31 (3H, d, J
D
6.0 Hz), 1.25 and 1.43 (each 3H, each s), 3.32 (1H, dd,
J 10.0 and 7.0 Hz), 3.33 (3H, s), 3.59 (1H, dd, J 9.2
and 3.0 Hz), 3.63 (1H, dd, J 10.0 and 1.2 Hz), 3.74
(1H, dq, J 10.0 and 6.0 Hz), 3.78 (1H, dd, J 9.0 and
9.0 Hz), 3.80 (1H, br d, J 10.0 Hz), 3.97 (1H, dd, J 9.2
and 9.0 Hz), 4.02–4.12 (1H, m), 4.05 (1H, d, J 5.2 Hz),
4.09 (1H, dd, J 7.0 and 5.2 Hz), 4.49 (1H, d, J 11.8
Hz), 4.52 (1H, d, J 10.0 Hz), 4.62 (1H, d, J 11.8 Hz),
4.71 (1H, d, J 11.4 Hz), 4.79 (1H, d, J 11.4 Hz), 4.82
(1H, br s), 4.83 (1H, d, J 10.0 Hz), 4.86 (1H, d, J 10.4
Hz), 4.95 (1H, d, J 10.4 Hz), 4.97 (1H, d, J 3.0 Hz),
7.14–7.19 (2H, m), 7.21–7.37 (18H, m). Anal. Calcd
for C44H52O10: C, 71.33; H, 7.07. Found: C, 71.33; H,
6.72.
4.2.8. Isopropyl 2,3,4,6-tetra-O-benzyl-b-D-glucopyrano-
side (20b). White solid, mp 109.0–110.5 ꢁC; Rf 0.38
27
(60:1 chloroform–EtOAc); ½aꢁ +12.0 (c 1.12, CHCl3);
D
1H NMR d 1.24 and 1.32 (each 3H, each d, J 6.0 Hz),
3.43 (1H, dd, J 8.8 and 8.8 Hz), 3.44 (1H, ddd, J 8.8,
4.2, and 1.6 Hz), 3.54 (1H, dd, J 8.8 and 8.8 Hz), 3.63

H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
345
4.2.12. Methyl 4-O-(2,3,4,6-tetra-O-benzyl-b-D-glucopyr-
anosyl)-2,3-O-isopropylidene-a-L-rhamnopyranoside
(22b). Colorless syrup, Rf 0.54 (3:1 n-hexane–EtOAc);
2 or 4). After stirring for 1 h at ꢀ78 ꢁC, the mixture
was filtered and the filtrate was concentrated in vacuo.
Purification of the residue by flash column chromato-
graphy gave the corresponding 2-deoxyglucopyrano-
sides or the olivosides, both of which selectively
included the b-anomers.
28
1
½aꢁ ꢀ15.6 (c 1.23, CHCl3); H NMR d 1.34 (3H, d, J
D
5.6 Hz), 1.32 and 1.46 (each 3H, each s), 3.34–3.46
(2H, m), 3.39 (3H, s), 3.58–3.76 (6H, m), 4.09 (1H, d,
J 5.2 Hz), 4.21 (1H, dd, J 6.8 and 5.2 Hz), 4.55 (1H, d,
J 11.8 Hz), 4.61 (1H, d, J 11.8 Hz), 4.69 (1H, d, J
10.8 Hz), 4.77 (1H, d, J 10.6 Hz), 4.82 (1H, d, J
10.6 Hz), 4.86 (1H, br s), 4.89 (1H, d, J 10.8 Hz), 4.91
(1H, d, J 10.8 Hz), 4.93 (1H, d, J 10.8 Hz), 4.94 (1H,
d, J 5.0 Hz), 7.16–7.22 (2H, m), 7.22–7.40 (18H, m).
Anal. Calcd for C44H52O10: C, 71.33; H, 7.07. Found:
C, 71.40; H, 6.82.
4.3.1. Methyl 2,3,4-tri-O-benzyl-6-O-(3,4,6-tri-O-benzyl-
2-deoxy-a-D-arabino-hexopyranosyl)-a-D-glucopyrano-
side (24a). Colorless syrup, Rf 0.24 (2:1 n-hexane–
28
D
1
EtOAc); ½aꢁ +65.4 (c 0.60, CHCl3); H NMR d 1.69
(1H, ddd, J 12.4, 12.4, and 4.0 Hz), 2.30 (1H, br dd, J
12.4 and 5.2 Hz), 3.34 (3H, s), 3.44–3.69 (7H, m),
3.70–3.75 (1H, m), 3.78–3.84 (1H, m), 3.89–4.02 (2H,
m), 4.36–4.70 (8H, m), 4.77–5.01 (6H, m), 7.12–7.38
(30H, m). Anal. Calcd for C55H60O10: C, 74.98; H,
6.86. Found: C, 74.92; H, 6.66.
4.2.13. Methyl 3-O-benzyl-2-O-(2,3,4,6-tetra-O-benzyl-a-
D-glucopyranosyl)-4,6-O-benzylidene-a-D-glucopyrano-
side (23a). White solid, mp 88.0–89.5 ꢁC; Rf 0.25 (10:1
28
chloroform–EtOAc); ½aꢁ +38.4 (c 0.66, CHCl3); 1H
4.3.2. Methyl 2,3,4-tri-O-benzyl-6-O-(3,4,6-tri-O-benzyl-
2-deoxy-b-D-arabino-hexopyranosyl)-a-D-glucopyrano-
D
NMR d 3.34–3.50 (2H, m), 3.46 (3H, s), 3.58 (1H, dd,
J 9.0 and 3.2 Hz), 3.60 (1H, dd, J 9.0 and 9.0 Hz),
3.67 (1H, dd, J 9.2 and 9.2 Hz), 3.73 (1H, dd, J 10.0
and 9.8 Hz), 3.79–3.91 (2H, m), 4.04–4.18 (3H, m),
4.28 (1H, d, J 12.0 Hz), 4.31 (1H, dd, J 9.0 and
4.4 Hz), 4.44 (1H, d, J 10.8 Hz), 4.52 (1H, d, J
12.0 Hz), 4.71 (1H, d, J 11.8 Hz), 4.78 (1H, d, J
10.2 Hz), 4.78–4.93 (4H, m), 4.84 (1H, d, J 3.6 Hz),
4.90 (1H, d, J 3.2 Hz), 5.01 (1H, d, J 10.6 Hz), 5.56
(1H, s), 6.97–7.05 (2H, m), 7.06–7.16 (2H, m), 7.17–
7.43 (34H, m), 7.46–7.53 (2H, m). Anal. Calcd for
C55H58O11: C, 73.81; H, 6.53. Found: C, 73.74; H, 6.33.
side (24b). White solid, mp 130.5–132.0 ꢁC; Rf 0.36 (2:1
27
n-hexane–EtOAc); ½aꢁ +23.5 (c 1.33, CHCl3); 1H NMR
D
d 1.53–1.68 (1H, m), 2.15 (1H, ddd, J 12.4, 4.8, and
1.6 Hz), 3.36 (3H, s), 3.30–3.78 (9H, m), 3.56–3.75
(4H, m), 3.99 (1H, dd, J 9.6 and 9.6 Hz), 4.07 (1H, dd,
J 10.8 and 2.0 Hz), 4.16 (1H, dd, J 10.0 and 1.6 Hz),
4.49–4.68 (8H, m), 4.77–4.89 (4H, m), 5.00 (1H, d, J
10.8 Hz), 7.18–7.38 (30H, m). Anal. Calcd for
C55H60O10: C, 74.98; H, 6.86. Found: C, 74.97; H, 6.68.
4.3.3. Cyclohexylmethyl 3,4,6-tri-O-benzyl-2-deoxy-a-D-
arabino-hexopyranoside (29a). Colorless syrup, Rf 0.36
29
D
4.2.14. Methyl 3-O-benzyl-2-O-(2,3,4,6-tetra-O-benzyl-b-
D-glucopyranosyl)-4,6-O-benzylidene-a-D-glucopyrano-
(5:2 n-hexane–ether); ½aꢁ +67.0 (c 0.88, CHCl3); 1H
NMR d 0.81–1.02 (2H, m), 1.05–1.35 (3H, m),
1.46–1.81 (7H, m), 2.27 (1H, br dd, J 12.4 and
4.8 Hz), 3.15 (1H, dd, J 9.2 and 6.0 Hz), 3.41 (1H, dd,
J 9.2 and 6.8 Hz), 3.56–3.83 (4H, m), 3.98 (1H, ddd, J
11.2, 8.4, and 4.8 Hz), 4.51 (2H, d, J 11.0 Hz), 4.64
(1H, d, J 11.0 Hz), 4.65 (1H, d, J 11.0 Hz), 4.68 (1H,
d, J 11.0 Hz), 4.89 (1H, d, J 11.0 Hz), 4.91 (1H, br d,
J 3.2 Hz), 7.14–7.20 (2H, m), 7.22–7.39 (13H, m). Anal.
Calcd for C34H42O5: C, 76.95; H, 7.98. Found: C, 76.93;
H, 7.97.
side (23b). White solid, mp 175.0–176.0 ꢁC; Rf 0.57
28
(10:1 chloroform–EtOAc); ½aꢁ +20.1 (c 1.05, CHCl3);
D
1H NMR d 3.36–3.49 (1H, m), 3.44 (3H, s), 3.49–3.70
(6H, m), 3.75 (1H, dd, J 10.0 and 10.0 Hz), 3.86 (1H,
dd, J 9.0 and 3.2 Hz), 3.92 (1H, dd, J 9.8 and 4.4 Hz),
4.10 (1H, dd, J 9.0 and 9.0 Hz), 4.32 (1H, dd, J 10.0
and 4.6 Hz), 4.52 (1H, d, J 10.6 Hz), 4.50 and 4.57 (each
1H, ABq, J 11.8 Hz), 4.66 (1H, d, J 10.6 Hz), 4.76 (1H,
d, J 11.2 Hz), 4.77 (1H, d, J 10.6 Hz), 4.78 (1H, d, J
10.6 Hz), 4.80 (1H, d, J 4.0 Hz), 4.81 (1H, d, J
10.6 Hz), 4.92 (1H, d, J 10.6 Hz), 4.96 (1H, d, J
3.2 Hz), 5.05 (1H, d, J 11.2 Hz), 5.56 (1H, s), 7.15–
7.41 (28H, m), 7.42–7.50 (2H, m). Anal. Calcd for
C55H58O11: C, 73.81; H, 6.53. Found: C, 73.79; H, 6.29.
4.3.4. Cyclohexylmethyl 3,4,6-tri-O-benzyl-2-deoxy-b-D-
arabino-hexopyranoside (29b). White solid, mp 72.0–
28
D
73.0 ꢁC; Rf 0.45 (5:2 n-hexane–ether); ½aꢁ ꢀ18.5 (c
1
1.32, CHCl3); H NMR d 0.82–1.02 (2H, m), 1.07–1.34
(3H, m), 1.50–1.84 (7H, m), 2.35 (1H, ddd, J 12.4, 4.8,
and 1.6 Hz), 3.22 (1H, dd, J 9.0 and 6.4 Hz), 3.40 (1H,
ddd, J 9.2, 4.4, and 1.6 Hz), 3.49 (1H, dd, J 9.2 and
8.0 Hz), 3.65 (1H, dd, J 11.0 and 4.4 Hz), 3.69 (1H,
ddd, J 12.0, 8.0, and 4.8 Hz), 3.73 (1H, dd, J 9.0 and
6.0 Hz), 3.77 (1H, dd, J 11.0 and 1.6 Hz), 4.40 (1H,
dd, J 9.6 and 1.6 Hz), 4.55 (1H, d, J 10.8 Hz), 4.57
(1H, d, J 11.6 Hz), 4.59 (1H, d, J 12.4 Hz), 4.63 (1H,
4.3. Glycosidation protocol for the preparations of 2-
deoxy- and 2,6-dideoxy-b-glucopyranosides
To a stirred solution of the glycosyl phosphite 2 (a/
b = 80/20, 0.1 mmol) or 4 (a/b = 72:28, 0.1 mmol) and
an alcohol (0.2 mmol) in dry Et2O (1 mL) was added
montmorillonite K-10 (100 wt % to the glycosyl donor

346
H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
d, J 12.4 Hz), 4.69 (1H, d, J 11.6 Hz), 4.90 (1H, d, J
10.8 Hz), 7.17–7.23 (2H, m), 7.23–7.38 (13H, m). Anal.
Calcd for C34H42O5: C, 76.95; H, 7.98. Found: C,
76.97; H, 7.62.
dd, J 12.8 and 5.2 Hz), 3.58–3.69 (2H, m), 3.77–3.86
(2H, m), 3.88 (1H, septet, J 6.0 Hz), 4.01 (1H, ddd, J
11.6, 8.8, and 5.2 Hz), 4.48–4.53 (2H, m), 4.63 (1H, d,
J 11.6 Hz), 4.66 (1H, d, J 12.4 Hz), 4.68 (1H, d, J
11.6 Hz), 4.89 (1H, d, J 10.8 Hz), 5.08 (1H, br d, J
3.6 Hz), 7.14–7.38 (15H, m). Anal. Calcd for
C30H36O5: C, 75.60; H, 7.61. Found: C, 75.63; H, 7.41.
4.3.5. n-Octyl 3,4,6-tri-O-benzyl-2-deoxy-a-D-arabino-
hexopyranoside (30a). Colorless syrup, Rf 0.36 (5:2 n-
29
D
1
hexane–ether); ½aꢁ +64.6 (c 1.40, CHCl3); H NMR d
0.84–0.93 (3H, m), 1.20–1.37 (10H, m), 1.44–1.62 (2H,
m), 1.72 (1H, ddd, J 12.8, 11.6, and 3.6 Hz), 2.28 (1H,
br dd, J 12.8 and 6.4 Hz), 3.34 (1H, dt, J 9.6 and
6.8 Hz), 3.55–3.82 (5H, m), 4.00 (1H, ddd, J 11.6, 8.8,
and 6.4 Hz), 4.43–4.60 (2H, m), 4.63 (1H, d, J
11.6 Hz), 4.65 (1H, d, J 12.0 Hz), 4.69 (1H, d, J
11.6 Hz), 4.89 (1H, d, J 10.4 Hz), 4.94 (1H, br d, J
3.6 Hz), 7.14–7.38 (15H, m). Anal. Calcd for
C35H46O5: C, 76.89; H, 8.48. Found: C, 76.90; H, 8.16.
4.3.10. Isopropyl 3,4,6-tri-O-benzyl-2-deoxy-b-D-arabino-
hexopyranoside (32b). Colorless syrup, Rf 0.27 (30:1
29
D
chloroform–EtOAc); ½aꢁ ꢀ25.9 (c 1.58, CHCl3); 1H
NMR d 1.15 (3H, d, J 6.0 Hz), 1.26 (3H, d, J 6.0 Hz),
1.65 (1H, ddd, J 12.8, 12.2, and 10.0 Hz), 2.30 (1H,
ddd, J 12.8, 5.6, and 1.6 Hz), 3.36–3.51 (2H, m), 3.61–
3.71 (3H, m), 4.01 (1H, septet, J 6.0 Hz), 4.49–4.65
(5H, m), 4.68 (1H, d, J 12.0 Hz), 4.89 (1H, d, J
10.8 Hz), 7.14–7.38 (15H, m). Anal. Calcd for
C30H36O5: C, 75.60; H, 7.61. Found: C, 75.65; H, 7.42.
4.3.6. n-Octyl 3,4,6-tri-O-benzyl-2-deoxy-b-D-arabino-
hexopyranoside (30b). Colorless syrup, Rf 0.47 (5:2 n-
4.3.11. Methyl 4-O-(3,4,6-tri-O-benzyl-2-deoxy-a-D-ara-
bino-hexopyranosyl)-2,3-O-isopropylidene-a-L-rhamno-
pyranoside (33a). Colorless syrup, Rf 0.28 (8:1 toluene–
28
D
1
hexane–ether); ½aꢁ ꢀ16.7 (c 0.98, CHCl3); H NMR d
0.84–0.92 (3H, m), 1.19–1.40 (10H, m), 1.53–1.71 (3H,
m), 2.34 (1H, ddd, J 12.8, 4.8, and 1.6 Hz), 3.36–3.53
(3H, m), 3.61–3.79 (3H, m), 3.89 (1H, dt, J 9.2 and
7.2 Hz), 4.42 (1H, dd, J 10.0 and 1.6 Hz), 4.53–4.65
(4H, m) 4.68 (1H, d, J 11.6 Hz), 4.90 (1H, d, J
10.0 Hz), 7.16–7.37 (15H, m). Anal. Calcd for
C35H46O5: C, 76.89; H, 8.48. Found: C, 76.92; H, 8.10.
28
1
EtOAc); ½aꢁ +63.0 (c 1.29, CHCl3); H NMR d 1.24
D
(3H, d, J 6.0 Hz), 1.25 and 1.44 (each 3H, each s),
1.73 (1H, ddd, J 12.4, 11.0, and 3.2 Hz), 2.26 (1H, dd,
J 12.4 and 4.6 Hz), 3.33 (1H, dd, J 10.0 and 6.4 Hz),
3.35 (3H, s), 3.60 (1H, dq, J 10.0 and 6.0 Hzz), 3.63
(1H, dd, J 10.2 and 1.4 Hz), 3.76 (1H, dd, J 9.0 and
9.0 Hz), 3.85 (1H, dd, J 10.2 and 1.6 Hz), 3.95 (1H,
ddd, J 11.0, 9.0, and 4.6 Hz), 3.97–4.07 (3H, m), 4.52
and 4.64 (each 1H, ABq, J 12.0 Hz), 4.56 and 4.90 (each
1H, ABq, J 10.6 Hz), 5.06 (1H, br d, J 3.2 Hz), 7.17–7.39
(15H, m). Anal. Calcd for C37H46O9: C, 70.01; H, 7.30.
Found: C, 69.99; H, 7.13.
4.3.7. Cyclohexyl 3,4,6-tri-O-benzyl-2-deoxy-a-D-ara-
bino-hexopyranoside (31a). Colorless syrup, Rf 0.46
28
(30:1 chloroform–EtOAc); ½aꢁ +80.6 (c 0.82, CHCl3);
D
1H NMR d 1.11–1.91 (11H, m), 2.24 (1H, br dd, J
12.8 and 5.2 Hz), 3.49–3.69 (3H, m), 3.72–3.89 (2H,
m), 4.02 (1H, ddd, J 11.6, 8.8, and 5.2 Hz), 4.47–4.54
(2H, m), 4.64 (1H, d, J 10.8 Hz), 4.65 (1H, d, J
12.0 Hz), 4.68 (1H, d, J 10.8 Hz), 4.89 (1H, d, J
10.8 Hz), 5.12 (1H, br d, J 4.8 Hz), 7.14–7.39 (15H,
m). Anal. Calcd for C33H40O5: C, 76.71; H, 7.80. Found:
C, 76.75; H, 7.49.
4.3.12. Methyl 4-O-(3,4,6-tri-O-benzyl-2-deoxy-b-D-ara-
bino-hexopyranosyl)-2,3-O-isopropylidene-a-L-rhamno-
pyranoside (33b). Colorless syrup, Rf 0.44 (8:1 toluene–
28
1
EtOAc); ½aꢁ ꢀ34.1 (c 1.91, CHCl3); H NMR d 1.33
D
(3H, d, J 5.2 Hz), 1.33 and 1.46 (each 3H, each s),
1.59 (1H, ddd, J 12.0, 11.6, and 10.0 Hz), 2.39 (1H,
ddd, J 12.0, 4.8, and 1.2 Hz), 3.31–3.41 (1H, m), 3.37
(3H, s), 3.58 (1H, dd, J 9.0 and 9.0 Hz), 3.58–3.73
(4H, m), 3.77 (1H, d, J 10.6 and 4.0 Hz), 4.08 (1H, d,
J 5.2 Hz), 4.17 (1H, dd, J 7.0 and 5.2 Hz), 4.57 and
4.63 (each 1H, ABq, J 10.2 Hz), 4.60 and 4.69 (each
1H, ABq, J 11.0 Hz), 4.60 and 4.90 (each 1H, ABq, J
10.2 Hz), 4.91 (1H, dd, J 10.0 and 1.2 Hz), 7.21–7.38
(15H, m). Anal. Calcd for C37H46O9: C, 70.01; H,
7.30. Found: C, 70.05; H, 7.02.
4.3.8. Cyclohexyl 3,4,6-tri-O-benzyl-2-deoxy-b-D-ara-
bino-hexopyranoside (31b). White solid, mp 48.0–
28
D
50.0 ꢁC; Rf 0.35 (30:1 chloroform–EtOAc); ½aꢁ ꢀ26.6
1
(c 1.00, CHCl3); H NMR d 1.13–2.05 (11H, m), 2.31
(1H, ddd, J 12.4, 5.2, and 1.6 Hz), 3.47–3.51 (2H, m),
3.61–3.80 (4H, m), 4.53–4.65 (5H, m), 4.69 (1H, d, J
12.0 Hz), 4.90 (1H, d, J 10.8 Hz), 7.19–7.47 (15H, m).
Anal. Calcd for C33H40O5: C, 76.71; H, 7.80. Found:
C, 76.74; H, 7.64.
4.3.9. Isopropyl 3,4,6-tri-O-benzyl-2-deoxy-a-D-arabino-
4.3.13. Methyl 3-O-benzyl-6-O-(3,4,6-tri-O-benzyl-2-
deoxy-a-D-arabino-hexopyranosyl)-2,6-dideoxy-a-D-ara-
bino-hexopyranoside (34a). Colorless syrup, Rf 0.43
hexopyranoside (32a). Colorless syrup, Rf 0.38 (30:1
28
chloroform–EtOAc); ½aꢁ +76.6 (c 1.88, CHCl3); 1H
D
28
1
NMR d 1.12 (3H, d, J 6.0 Hz), 1.16 (3H, d, J 6.0 Hz),
1.74 (1H, ddd, J 12.8, 11.6, and 3.6 Hz), 2.24 (1H, br
(6:1 toluene–EtOAc); ½aꢁ +67.1 (c 1.08, CHCl3); H
D
NMR d 1.27 (3H, d, J 5.8 Hz), 1.61 (1H, ddd, J 12.8,

H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
347
11.6, and 3.8 Hz), 1.65 (1H, ddd, J 12.8, 11.0, and
4.0 Hz), 2.16 (1H, dd, J 12.8 and 4.6 Hz), 2.27 (1H,
dd, J 12.8 and 4.8 Hz), 3.31 (3H, s), 3.34 (1H, dd, J
9.0 and 9.0 Hz), 3.55–3.69 (1H, m), 3.60 (1H, dd, J 9.4
and 9.0 Hz), 3.63 (1H, br d, J 10.0 Hz), 3.75–3.95 (2H,
m), 3.80 (1H, dd, J 10.0 and 3.2 Hz), 3.89 (1H, ddd, J
11.6, 9.0, and 4.6 Hz), 4.43 (1H, d, J 11.2 Hz), 4.49
(1H, d, J 12.0 Hz), 4.50 (1H, d, J 10.2 Hz), 4.60 (2H,
s, ArCH2 and 1H, d, J 11.6 Hz), 4.64 (1H, d, J
12.0 Hz), 4.73 (1H, br d, J 3.8 Hz), 4.86 (1H, d, J
12.0 Hz), 5.53 (1H, br d, J 4.8 Hz), 7.14–7.37 (20H,
m). Anal. Calcd for C41H48O8: C, 73.63; H, 7.23. Found:
C, 73.72; H, 7.21.
1.2 Hz), 3.37 (3H, s), 3.41 (1H, dq, J 9.4 and 6.0 Hz),
3.48–3.59 (3H, m), 3.59 (1H, ddd, J 11.6, 9.2, and
4.8 Hz), 3.77 (1H, ddd, J 10.0, 2.2, and 1.2 Hz), 4.00
(1H, dd, J 9.0 and 8.8 Hz), 4.06 (1H, dd, J 10.0 and
1.2 Hz), 4.25 (1H, dd, J 9.4 and 1.2 Hz), 4.44 (1H, d, J
12.0 Hz), 4.59 (1H, d, J 12.0 Hz), 4.59 (1H, d, J 11.2
Hz), 4.61 (1H, d, J 3.2 Hz), 4.66 (1H, d, J 12.0 Hz),
4.79 (1H, d, J 12.0 Hz), 4.81 (1H, d, J 10.6 Hz), 4.89
(1H, d, J 11.2 Hz), 4.98 (1H, dd, J 9.4 and 9.2 Hz),
5.00 (1H, d, J 10.6 Hz), 7.11–7.20 (5H, m), 7.22–7.40
(15H, m), 7.41–7.51 (2H, m), 7.55–7.64 (1H, m),
7.97–8.06 (2H, m). Anal. Calcd for C48H52O10: C, 73.08;
H, 6.64. Found: C, 73.02; H, 6.42.
4.3.14. Methyl 3-O-benzyl-6-O-(3,4,6-tri-O-benzyl-2-
deoxy-b-D-arabino-hexopyranosyl)-2,6-dideoxy-a-D-ara-
bino-hexopyranoside (34b). Colorless syrup, Rf 0.30
4.3.17. Cyclohexylmethyl 3-O-benzyl-4-O-benzoyl-2,6-
dideoxy-a-D-arabino-hexopyranoside (35a). Colorless
28
syrup, Rf 0.38 (3:1 n-hexane–ether); ½aꢁ +37.2 (c 0.91,
D
27
1
1
(6:1 toluene–EtOAc); ½aꢁ +62.1 (c 1.51, CHCl3); H
CHCl3); H NMR d 0.85–1.05 (2H, m), 1.10–1.37 (3H,
D
NMR d 1.27 (3H, d, J 6.2 Hz), 1.61 (1H, ddd, J 13.0,
11.0, and 10.8 Hz), 1.68 (1H, ddd, J 12.4, 11.0, and
3.2 Hz), 2.20 (1H, ddd, J 13.0, 4.8, and 1.2 Hz), 2.34
(1H, dd, J 12.4 and 4.4 Hz), 3.28 (3H, s), 3.23–3.38
(2H, m), 3.54 (1H, dd, J 8.6 and 8.6 Hz), 3.61 (1H,
ddd, J 11.0, 8.6, and 4.4 Hz), 3.63–3.67 (2H, m), 3.70
(1H, dq, J 9.2 and 6.2 Hz), 3.87 (1H, ddd, J 10.8, 8.0,
and 4.8 Hz), 4.47 (1H, d, J 11.8 Hz), 4.52 (1H, d, J 11.8
Hz), 4.56 (1H, d, J 10.4 Hz), 4.59 (1H, d, J 11.4 Hz),
4.59 (1H, dd, J 11.0 and 1.2 Hz), 4.60 (1H, d, J
11.0 Hz), 4.66 (1H, d, J 11.0 Hz), 4.71 (1H, br d), 4.77
(1H, d, J 11.4 Hz), 4.87 (1H, d, J 10.4 Hz), 7.16–7.36
(20H, m). Anal. Calcd for C41H48O8: C, 73.63; H,
7.23. Found: C, 73.27; H, 6.90.
m), 1.20 (3H, d, J 6.0 Hz), 1.51–1.87 (6H, m), 1.80
(1H, ddd, J 13.0, 11.0, and 3.2 Hz), 2.32 (1H, dd, J
13.0 and 4.8 Hz), 3.18 (1H, dd, J 9.2 and 6.0 Hz), 3.43
(1H, dd, J 9.2 and 6.8 Hz), 3.87 (1H, dq, J 9.2 and
6.0 Hz), 3.99 (1H, ddd, J 11.0, 9.0, and 4.8 Hz), 4.48
and 4.60 (each 1H, ABq, J 11.6 Hz), 4.88 (1H, br d, J
3.2 Hz), 5.03 (1H, dd, J 9.2 and 9.0 Hz), 7.12–7.18
(5H, m), 7.41–7.50 (2H, m), 7.53–7.63 (1H, m),
8.00–8.09 (2H, m). Anal. Calcd for C27H34O5: C, 73.94;
H, 7.81. Found: C, 73.93; H, 7.85.
4.3.18. Cyclohexylmethyl 3-O-benzyl-4-O-benzoyl-2,6-
dideoxy-b-D-arabino-hexopyranoside (35b). White so-
27
D
lid, mp 64.5–66.5 ꢁC; Rf 0.51 (3:1 n-hexane–ether); ½aꢁ
1
ꢀ71.4 (c 0.67, CHCl3); H NMR d 0.82–1.03 (2H, m),
4.3.15. Methyl 2,3,4-tri-O-benzyl-6-O-(3-O-benzyl-4-O-
benzoyl-2,6-dideoxy-a-D-arabino-hexopyranosyl)-a-D-gluco-
1.12–1.34 (3H, m), 1.26 (3H, d, J 6.0 Hz), 1.50–1.85
(6H, m), 1.76 (1H, ddd, J 12.4, 11.6, and 9.6 Hz), 2.38
(1H, ddd, J 12.4, 4.8, and 1.6 Hz), 3.22 (1H, dd, J 9.2
and 6.8 Hz), 3.49 (1H, dq, J 9.2 and 6.0 Hz), 3.68 (1H,
ddd, J 11.6, 9.0, and 4.8 Hz), 3.71 (1H, dd, J 9.2 and
6.2 Hz), 4.46 (1H, dd, J 9.6 and 1.6 Hz), 4.46 and 4.62
(each 1H, ABq, J 12.0 Hz), 5.02 (1H, dd, J 9.2 and
9.0 Hz), 7.12–7.21 (5H, m), 7.41–7.52 (2H, m), 7.54–
7.63 (1H, m), 7.97–8.07 (2H, m). Anal. Calcd for
C27H34O5: C, 73.94; H, 7.81. Found: C, 73.86; H, 7.82.
pyranoside (26a). White solid, mp 92.0–94.0 ꢁC; Rf
29
0.37 (4:1 toluene–EtOAc); ½aꢁ +58.6 (c 0.56, CHCl3);
D
1H NMR d 1.09 (3H, d, J 6.0 Hz), 1.77 (1H, ddd, J
12.6, 11.0, and 3.2 Hz), 2.35 (1H, dd, J 12.6 and
4.8 Hz), 3.37 (3H, s), 3.49–3.64 (3H, m), 3.71–3.91
(3H, m), 3.91 (1H, ddd, J 11.0, 9.0, and 4.8 Hz), 4.02
(1H, dd, J 9.0 and 9.0 Hz), 4.43 (1H, d, J 11.8 Hz),
4.53–4.62 (2H, m), 4.65 (1H, d, J 3.2 Hz), 4.71 (1H, d,
J 11.2 Hz), 4.82 (1H, d, J 12.2 Hz), 4.83 (1H, br d, J
3.2 Hz), 4.94 (1H, d, J 10.2 Hz), 4.99 (1H, dd, J 9.2
and 9.0 Hz), 5.00 (1H, d, J 11.2 Hz), 5.02 (1H, d, J
10.2 Hz), 7.08–7.15 (5H, m), 7.21–7.47 (17H, m), 7.52–
7.62 (1H, m), 7.88–7.97 (2H, m). Anal. Calcd for
C48H52O10: C, 73.08; H, 6.64. Found: C, 73.04; H, 6.67.
4.3.19. n-Octyl 3-O-benzyl-4-O-benzoyl-2,6-dideoxy-a-D-
arabino-hexopyranoside (36a). Colorless syrup, Rf 0.37
29
D
(3:1 n-hexane–ether); ½aꢁ +32.0 (c 1.38, CHCl3); 1H
NMR d 0.90 (3H, t, J 6.2 Hz), 1.21 (3H, d, J 6.0 Hz),
1.24–1.42 (10H, m), 1.51–1.67 (2H, m), 1.81 (1H, ddd,
J 12.6, 11.0, and 3.2 Hz), 2.32 (1H, dd, J 12.6 and
4.8 Hz), 3.38 (1H, dt, J 9.5 and 6.2 Hz), 3.63 (1H, dt,
J 9.5 and 6.2 Hz), 3.89 (1H, dq, J 9.2 and 6.0 Hz),
4.00 (1H, ddd, J 11.0, 9.0, and 4.8 Hz), 4.48 and 4.60
(each 1H, ABq, J 12.0 Hz), 4.91 (1H, br d, J 3.2 Hz),
5.03 (1H, dd, J 9.2 and 9.0 Hz), 7.13–7.18 (5H, m),
7.40–7.50 (2H, m), 7.53–7.63 (1H, m), 8.01–8.09 (2H,
4.3.16. Methyl 2,3,4-tri-O-benzyl-6-O-(3-O-benzyl-4-O-
benzoyl-2,6-dideoxy-b-D-arabino-hexopyranosyl)-a-D-gluco-
pyranoside (26b). White solid, mp 154–156 ꢁC; Rf 0.49
28
(4:1 toluene–EtOAc); ½aꢁ ꢀ9.0 (c 1.07, CHCl3); 1H
D
NMR d 1.22 (3H, d, J 6.0 Hz), 1.75 (1H, ddd, J 12.4,
11.6, and 9.4 Hz), 2.21 (1H, ddd, J 12.4, 4.8, and

348
H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
m). Anal. Calcd for C28H38O5: C, 73.98; H, 8.43. Found:
C, 74.05; H, 8.44.
(1H, m), 8.01–8.10 (2H, m). Anal. Calcd for
C23H28O5: C, 71.85; H, 7.34. Found: C, 71.80; H, 7.38.
4.3.20. n-Octyl 3-O-benzyl-4-O-benzoyl-2,6-dideoxy-b-D-
4.3.24. Isopropyl 3-O-benzyl-4-O-benzoyl-2,6-dideoxy-b-
arabino-hexopyranoside (36b). Colorless syrup, Rf 0.51
D-arabino-hexopyranoside (38b). Colorless syrup, Rf
29
D
28
D
(3:1 n-hexane–ether); ½aꢁ ꢀ64.6 (c 1.30, CHCl3); 1H
0.19 (30:1 chloroform–EtOAc); ½aꢁ ꢀ86.1 (c 1.51,
1
NMR d 0.88 (3H, t, J 6.2 Hz), 1.20–1.40 (10H, m),
1.26 (3H, d, J 6.0 Hz), 1.52–1.68 (2H, m), 1.77 (1H,
ddd, J 12.4, 12.0, and 9.6 Hz), 2.38 (1H, ddd, J 12.4,
4.8, and 1.4 Hz), 3.44 (1H, dt, J 9.0 and 6.2 Hz), 3.50
(1H, dq, J 9.2 and 6.0 Hz), 3.68 (1H, ddd, J 12.0, 9.0,
and 4.8 Hz), 3.89 (1H, dt, J 9.0 and 6.2 Hz), 4.48 (1H,
dd, J 9.6 and 1.4 Hz), 4.46 and 4.61 (each 1H, ABq, J
12.0 Hz), 5.02 (1H, dd, J 9.2 and 9.0 Hz), 7.12–7.21
(5H, m), 7.41–7.51 (2H, m), 7.55–7.64 (1H, m),
7.98–8.07 (2H, m). Anal. Calcd for C28H38O5: C,
73.98; H, 8.43. Found: C, 74.04; H, 8.46.
CHCl3); H NMR d 1.17 (3H, d, J 6.0 Hz), 1.26 (3H,
d, J 6.0 Hz), 1.26 (3H, d, J 6.0 Hz), 1.78 (1H, ddd, J
12.2, 11.0, and 9.6 Hz), 2.34 (1H, ddd, J 12.2, 5.0, and
1.4 Hz), 3.51 (1H, dq, J 9.2 and 6.0 Hz), 3.69 (1H,
ddd, J 11.0, 9.0, and 5.0 Hz), 4.02 (1H, septet, J
6.0 Hz), 4.46 and 4.62 (each 1H, ABq, J 12.0 Hz), 4.59
(1H, dd, J 9.6 and 1.4 Hz), 5.03 (1H, dd, J 9.2 and
9.0 Hz), 7.13–7.21 (5H, m), 7.42–7.52 (2H, m),
7.55–7.63 (1H, m), 7.99–8.05 (2H, m). Anal. Calcd for
C23H28O5: C, 71.85; H, 7.34. Found: C, 71.77; H, 7.35.
4.3.25. Methyl 4-O-(3-O-benzyl-4-O-benzoyl-2,6-dide-
oxy-a-D-arabino-hexopyranosyl)-2,3-O-isopropylidene-a-
L-rhamnopyranoside (39a). Colorless syrup, Rf 0.38
4.3.21. Cyclohexyl 3-O-benzyl-4-O-benzoyl-2,6-dideoxy-
a-D-arabino-hexopyranoside (37a). Colorless syrup, Rf
29
0.34 (30:1 chloroform–EtOAc); ½aꢁ +46.6 (c 1.98,
28
1
(5:2 n-hexane–EtOAc); ½aꢁ +49.5 (c 0.79, CHCl3); H
D
D
1
CHCl3); H NMR d 1.14–1.48 (5H, m), 1.20 (3H, d, J
NMR d 1.20 (3H, d, J 6.0 Hz), 1.27 (3H, d, J 6.0 Hz),
1.34 and 1.54 (each 3H, each s), 1.82 (1H, ddd, J 12.6,
11.0, and 3.4 Hz), 2.31 (1H, ddd, J 12.6, 4.8, and
1.0 Hz), 3.38 (3H, s), 3.35–3.43 (1H, m), 3.65 (1H, dq,
J 9.4 and 6.0 Hz), 3.96 (1H, ddd, J 11.0, 9.2, and
4.8 Hz), 4.07–4.13 (2H, m), 4.20 (1H, d, J 11.6 Hz),
4.46 (1H, d, J 11.6 Hz), 4.59 (1H, d, J 11.6 Hz), 4.86
(1H, br s), 5.04 (1H, dd, J 3.4 and 1.0 Hz), 5.04 (1H,
dd, J 9.4 and 9.2 Hz), 7.11–7.20 (5H, m), 7.41–7.52
(2H, m), 7.54–7.63 (1H, m), 8.03–8.12 (2H, m). Anal.
Calcd for C30H38O9: C, 66.40; H, 7.06. Found: C,
66.30; H, 7.09.
6.0 Hz), 1.48–1.63 (1H, m), 1.65–1.96 (5H, m), 2.28
(1H, dd, J 12.6 and 4.8 Hz), 3.47–3.63 (1H, m), 3.97
(1H, dq, J 9.2 and 6.0 Hz), 4.02 (1H, ddd, J 11.0, 9.0,
and 4.8 Hz), 4.48 and 4.60 (each 1H, ABq, J 12.0 Hz),
5.03 (1H, dd, J 9.2 and 9.0 Hz), 5.08 (1H, br d, J
3.2 Hz), 7.12–7.18 (5H, m), 7.40–7.50 (2H, m),
7.53–7.62 (1H, m), 8.01–8.09 (2H, m). Anal. Calcd for
C26H32O5: C, 73.56; H, 7.60. Found: C, 73.58; H, 7.70.
4.3.22. Cyclohexyl 3-O-benzyl-4-O-benzoyl-2,6-dideoxy-
b-D-arabino-hexopyranoside (37b). White solid, mp
29
D
74.5–76.0 ꢁC; Rf 0.24 (30:1 chloroform–EtOAc); ½aꢁ
1
ꢀ77.9 (c 1.55, CHCl3); H NMR d 1.12–1.49 (5H, m),
4.3.26. Methyl 4-O-(3-O-benzyl-4-O-benzoyl-2,6-dide-
oxy-b-D-arabino-hexopyranosyl)-2,3-O-isopropylidene-a-
L-rhamnopyranoside (39b). Colorless syrup, Rf 0.47
1.26 (3H, d, J 6.0 Hz), 1.49–1.63 (1H, m), 1.66–2.04
(5H, m), 2.34 (1H, ddd, J 12.4, 4.8, and 1.6 Hz), 3.50
(1H, dq, J 9.2 and 6.0 Hz), 3.60–3.76 (1H, m), 3.68
(1H, ddd, J 11.0, 9.0, and 4.8 Hz), 4.45 and 4.62 (each
1H, ABq, J 12.0 Hz), 4.63 (1H, dd, J 9.6 and 1.6 Hz),
5.03 (1H, dd, J 9.2 and 9.0 Hz), 7.13–7.21 (5H, m),
7.42–7.52 (2H, m), 7.54–7.64 (1H, m), 7.99–8.07 (2H,
m). Anal. Calcd for C26H32O5: C, 73.56; H, 7.60. Found:
C, 73.59; H, 7.61.
28
1
(5:2 n-hexane–EtOAc); ½aꢁ ꢀ77.4 (c 0.98, CHCl3); H
D
NMR d 1.24 (3H, d, J 6.0 Hz), 1.30 (3H, d, J 6.0 Hz),
1.36 and 1.52 (each 3H, each s), 1.67 (1H, ddd, J 12.0,
11.8, and 9.4 Hz), 2.42 (1H, ddd, J 12.0, 5.0, and
1.6 Hz), 3.37 (3H, s), 3.47 (1H, dq, J 9.2 and 6.0 Hz),
3.61 (1H, dq, J 9.6 and 5.6 Hz), 3.68 (1H, dd, J 9.6
and 6.8 Hz), 3.70 (1H, ddd, J 11.8, 9.0, and 5.0 Hz),
4.09 (1H, d, J 5.6 Hz), 4.17 (1H, d, J 6.8 and 5.6 Hz),
4.45 and 4.61 (each 1H, ABq, J 12.0 Hz), 4.86 (1H, br
s), 4.95 (1H, dd, J 9.6 and 1.6 Hz), 5.02 (1H, dd, J 9.2
and 9.0 Hz), 7.12–7.21 (5H, m), 7.41–7.52 (2H, m),
7.54–7.63 (1H, m), 8.03–8.12 (2H, m). Anal. Calcd for
C30H38O9: C, 66.40; H, 7.06. Found: C, 66.23; H, 6.91.
4.3.23. Isopropyl 3-O-benzyl-4-O-benzoyl-2,6-dideoxy-a-
D-arabino-hexopyranoside (38a). Colorless syrup, Rf
28
D
0.29 (30:1 chloroform–EtOAc); ½aꢁ +36.7 (c 1.20,
1
CHCl3); H NMR d 1.16 (3H, d, J 6.0 Hz), 1.20 (3H,
d, J 6.0 Hz), 1.22 (3H, d, J 6.0 Hz), 1.82 (1H, ddd, J
12.6, 11.0, and 3.2 Hz), 2.27 (1H, dd, J 12.6 and
4.8 Hz), 3.89 (1H, septet, J 6.0 Hz), 3.97 (1H, dq, J 9.2
and 6.0 Hz), 4.01 (1H, ddd, J 11.0, 9.0, and 4.8 Hz),
4.47 and 4.60 (each 1H, ABq, J 12.0 Hz), 5.03 (1H,
dd, J 9.2 and 9.0 Hz), 5.04 (1H, br d, J 3.2 Hz),
7.12–7.18 (5H, m), 7.40–7.50 (2H, m), 7.53–7.63
4.3.27. Methyl 3-O-benzyl-6-O-(3-O-benzyl-4-O-benzoyl-
2,6-dideoxy-a-D-arabino-hexopyranosyl)-2,6-dideoxy-a-
D-arabino-hexopyranoside (40a). Colorless syrup, Rf
28
D
0.47 (2:1 n-hexane–EtOAc); ½aꢁ +37.3 (c 2.10, CHCl3);
1H NMR d 1.19 (3H, d, J 6.0 Hz), 1.32 (3H, d, J 6.0 Hz),

H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
349
1.64 (1H, ddd, J 12.6, 11.0, and 3.2 Hz), 1.74 (1H, ddd, J
12.6, 11.0, and 3.6 Hz), 2.22 (1H, ddd, J 12.6, 4.8, and
1.2 Hz), 2.30 (1H, ddd, J 12.6, 4.8, and 1.2 Hz), 3.33
(3H, s), 3.34 (1H, dd, J 9.0 and 9.0 Hz), 3.70 (1H, dq,
J 9.0 and 6.0 Hz), 3.86 (1H, ddd, J 9.0, 9.0, and
4.8 Hz), 3.91 (1H, ddd, J 9.0, 9.0, and 4.8 Hz), 4.00
(1H, dq, J 9.0 and 6.0 Hz), 4.43 and 4.55 (each 1H,
ABq, J 11.6 Hz), 4.45 and 4.62 (each 1H, ABq, J
11.4 Hz), 4.76 (1H, dd, J 3.2 and 1.2 Hz), 5.00 (1H,
dd, J 9.0 and 9.0 Hz), 5.46 (1H, dd, J 3.2 and 1.2 Hz),
7.11–7.19 (5H, m), 7.28–7.36 (5H, m), 7.42–7.49 (2H,
m), 7.55–7.62 (2H, m), 8.02–8.07 (2H, m). Anal. Calcd
for C34H40O8: C, 70.81; H, 6.99. Found: C, 70.68; H,
6.88.
(1H, dd, J 8.8 and 8.6 Hz), 3.24 (1H, dq, J 8.8 and
5.8 Hz), 3.36 (3H, s), 3.47–3.60 (4H, m), 3.68–3.78
(1H, m), 3.99 (1H, dd, J 9.0 and 9.0 Hz), 4.03 (1H, dd,
J 10.0 and 1.4 Hz), 4.15 (1H, dd, J 9.4 and 1.2 Hz),
4.57 (1H, d, J 11.2 Hz), 4.58 (1H, d, J 12.0 Hz),
4.57–4.59 (4H, m), 4.79 (1H, d, J 12.0 Hz), 4.81 (1H,
d, J 10.4 Hz), 4.87 (1H, d, J 11.0 Hz), 4.92 (1H, d, J
10.8 Hz), 4.99 (1H, d, J 10.4 Hz), 7.21–7.39 (25H, m).
Anal. Calcd for C48H54O9: C, 74.39; H, 7.02. Found:
C, 74.38; H, 6.80.
4.3.31. Methyl 2,3,4-tri-O-benzyl-6-O-(4-O-benzyl-3-O-
benzoyl-2,6-dideoxy-a-D-arabino-hexopyranosyl)-a-D-gluco-
pyranoside (27a). White solid, mp 132.8–135.5 ꢁC; Rf
29
0.50 (2:1 n-hexane–EtOAc); ½aꢁ +44.0 (c 1.50, CHCl3);
D
4.3.28. Methyl 3-O-benzyl-6-O-(3-O-benzyl-4-O-benzoyl-
2,6-dideoxy-b-D-arabino-hexopyranosyl)-2,6-dideoxy-a-
1H NMR d 1.23 (3H, d, J 6.0 Hz), 1.80 (1H, ddd, J 12.2,
11.0, and 3.2 Hz), 2.46 (1H, dd, J 12.2 and 5.0 Hz), 3.33
(1H, dd, J 9.0 and 9.0 Hz), 3.38 (3H, s), 3.52–3.67 (3H,
m), 3.72–3.80 (3H, m), 4.00 (1H, dd, J 9.2 and 9.0 Hz),
4.59 (1H, d, J 3.6 Hz), 4.60 (1H, d, J 11.0 Hz), 4.64 (1H,
d, J 11.0 Hz), 4.67 (1H, d, J 12.0 Hz), 4.72 (1H, d, J 11.0
Hz), 4.80 (1H, d, J 12.0 Hz), 4.82 (1H, d, J 11.0 Hz),
4.94 (1H, br d, J 3.2 Hz), 4.97 (1H, d, J 11.0 Hz), 5.00
(1H, d, J 11.0 Hz), 5.54 (1H, ddd, J 11.0, 9.0, and
5.0 Hz), 7.14–7.40 (20H, m), 7.40–7.49 (2H, m),
7.52–7.61 (1H, m), 7.98–8.07 (2H, m). Anal. Calcd for
C48H52O10: C, 73.08; H, 6.64. Found: C, 73.00; H,
6.49.
D-arabino-hexopyranoside (40b). Colorless syrup, Rf
28
0.36 (2:1 n-hexane–EtOAc); ½aꢁ +31.7 (c 1.58, CHCl3);
D
1H NMR d 1.19 (3H, d, J 6.0 Hz), 1.29 (3H, d, J 6.0 Hz),
1.69 (1H, ddd, J 13.0, 11.0, and 3.2 Hz), 1.74 (1H, ddd, J
12.4, 11.4, and 9.6 Hz), 2.24 (1H, ddd, J 13.0, 4.8, and
1.2 Hz), 2.39 (1H, ddd, J 12.4, 4.8, and 1.6 Hz), 3.31
(3H, s), 3.32 (1H, dd, J 9.0 and 8.4 Hz), 3.41 (1H, dq,
J 9.0 and 6.0 Hz), 3.64 (1H, ddd, J 11.4, 8.8, and
4.8 Hz), 3.72 (1H, dq, J 9.0 and 6.0 Hz), 3.88 (1H,
ddd, J 11.0, 8.4, and 4.8 Hz), 4.45 and 4.60 (each 1H,
ABq, J 12.0 Hz), 4.62 and 4.76 (each 1H, ABq, J
11.4 Hz), 4.71–4.75 (1H, m), 4.75 (1H, dd, J 9.6 and
1.6 Hz), 5.01 (1H, dd, J 9.0 and 8.8 Hz), 7.12–7.21
(5H, m), 7.21–7.40 (5H, m), 7.42–7.50 (2H, m), 7.56–
7.63 (2H, m), 7.99–8.04 (2H, m). Anal. Calcd for
C34H40O8: C, 70.81; H, 6.99. Found: C, 70.72; H, 6.85.
4.3.32. Methyl 2,3,4-tri-O-benzyl-6-O-(4-O-benzyl-3-O-
benzoyl-2,6-dideoxy-b-D-arabino-hexopyranosyl)-a-D-gluco-
pyranoside (27b). White solid, mp 140.5–143 ꢁC; Rf
28
0.50 (2:1 n-hexane–EtOAc); ½aꢁ ꢀ4.9 (c 0.42, CHCl3);
D
1H NMR d 1.34 (3H, d, J 5.6 Hz), 1.72 (1H, ddd, J
12.0, 11.8, and 9.6 Hz), 2.32 (1H, ddd, J 12.0, 5.0, and
1.2 Hz), 3.31 (1H, dd, J 9.0 and 8.4 Hz), 3.35 (3H, s),
3.39 (1H, dq, J 9.0 and 5.6 Hz), 3.45–3.60 (3H, m),
3.68–3.77 (1H, m), 3.98 (1H, dd, J 9.2 and 8.8 Hz),
4.03 (1H, dd, J 12.4 and 1.4 Hz), 4.28 (1H, dd, J 9.6
and 1.2 Hz), 4.57 (1H, d, J 11.0 Hz), 4.58 (1H, d, J
3.0 Hz), 4.59 (1H, d, J 10.6 Hz), 4.64 (1H, d, J 11.6
Hz), 4.70 (1H, d, J 10.6 Hz), 4.78 (1H, d, J 11.6 Hz),
4.81 (1H, d, J 11.0 Hz), 4.87 (1H, d, J 11.0 Hz), 4.99
(1H, d, J 11.0 Hz), 5.19 (1H, ddd, J 11.8, 8.2, and
5.0 Hz), 7.14–7.40 (20H, m), 7.53–7.62 (1H, m),
7.98–8.06 (2H, m). Anal. Calcd for C48H52O10: C,
73.08; H, 6.64. Found: C, 72.92; H, 6.49.
4.3.29. Methyl 2,3,4-tri-O-benzyl-6-O-(3,4-di-O-benzyl-
2,6-dideoxy-a-D-arabino-hexopyranosyl)-a-D-glucopyrano-
side (25a). White solid, mp 95.5–97.0 ꢁC; Rf 0.46 (2:1
29
n-hexane–EtOAc); ½aꢁ +59.1 (c 1.31, CHCl3); 1H
D
NMR d 1.17 (3H, d, J 6.0 Hz), 1.64 (1H, ddd, J 12.8,
11.2, and 3.2 Hz), 2.31 (1H, dd, J 12.8 and 3.8 Hz),
3.09 (1H, dd, J 9.0 and 8.8 Hz), 3.35 (3H, s), 3.46–3.61
(3H, m), 3.68 (1H, dq, J 9.0 and 6.0 Hz), 3.74 (1H, br
d, J 11.0 Hz), 3.81 (1H, dd, J 11.0 and 3.6 Hz), 3.90
(1H, ddd, J 11.0, 8.4, and 4.8 Hz), 4.00 (1H, dd, J 9.0
and 8.8 Hz), 4.57 (1H, d, J 10.4 Hz), 4.59–4.66 (4H,
m), 4.68 (1H, d, J 11.8 Hz), 4.80 (1H, d, J 11.8 Hz),
4.81 (1H, d, J 10.2 Hz), 4.87–4.97 (3H, m), 5.00 (1H,
d, J 10.2 Hz), 7.19–7.41 (25H, m). Anal. Calcd for
C48H54O9: C, 74.39; H, 7.02. Found: C, 74.30; H, 6.83.
4.3.33. Methyl 2,3,4-tri-O-benzyl-6-O-(3,4-di-O-benzoyl-
2,6-dideoxy-a-D-arabino-hexopyranosyl)-a-D-glucopyrano-
side (28a). Colorless syrup, Rf 0.47 (2:1 n-hexane–
4.3.30. Methyl 2,3,4-tri-O-benzyl-6-O-(3,4-di-O-benzyl-
2,6-dideoxy-b-D-arabino-hexopyranosyl)-a-D-glucopyrano-
28
D
1
EtOAc); ½aꢁ +42.8 (c 0.78, CHCl3); H NMR d 1.16
side (25b). White solid, mp 140.5–142.5 ꢁC; Rf 0.59 (2:1
(3H, d, J 6.0 Hz), 1.93 (1H, ddd, J 12.4, 11.0, and
3.2 Hz), 2.53 (1H, dd, J 12.4 and 4.8 Hz), 3.42 (3H, s),
3.61 (1H, dq, J 9.0 and 6.0 Hz), 3.56–3.70 (2H, m),
3.77–3.86 (1H, m), 3.91 (1H, dd, J 11.0 and 3.8 Hz),
28
n-hexane–EtOAc); ½aꢁ +14.5 (c 0.41, CHCl3); 1H NMR
D
d 1.28 (3H, d, J 6.0 Hz), 1.60 (1H, ddd, J 12.2, 11.2, and
9.4 Hz), 2.16 (1H, ddd, J 12.2, 4.6, and 1.2 Hz), 3.09

350
H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
4.02 (1H, dd, J 9.0 and 3.2 Hz), 4.03 (1H, dd, J 9.0 and
9.0 Hz), 4.63 (1H, d, J 3.2 Hz), 4.69 and 4.82 (each 1H,
ABq, J 12.0 Hz), 4.83 and 5.02 (each 1H, ABq, J
10.4 Hz), 4.72 and 5.05 (each 1H, ABq, J 11.0 Hz),
5.03 (1H, br d,, J 3.2 Hz), 5.18 (1H, dd, J 9.2 and
9.0 Hz), 5.61 (1H, ddd, J 11.0, 9.2, and 4.8 Hz),
7.21–7.43 (19H, m), 7.43–7.53 (2H, m), 7.85–7.96
(4H, m). Anal. Calcd for C48H50O11: C, 71.80; H,
6.28. Found: C, 71.72; H, 6.34.
4.4.2. Methyl 2,3,4-tri-O-benzyl-6-O-(2,3-di-O-benzyl-
4,6-O-benzylidene-b-D-mannopyranosyl)-a-D-glucopyrano-
side (41b). White solid, mp 158.5–160 ꢁC; Rf 0.42 (6:1
27
1
toluene–EtOAc); ½aꢁ ꢀ5.8 (c 0.94, CHCl3); H NMR
D
d 3.22 (1H, ddd, J 10.0, 9.2, and 4.6 Hz), 3.33 (3H, s),
3.39–3.54 (4H, m), 3.69 (1H, d, J 2.6 Hz), 3.75 (1H,
ddd, J 9.6, 4.6, and 1.6 Hz), 3.90 (1H, dd, J 10.0 and
10.0 Hz), 4.01 (1H, dd, J 9.0 and 9.0 Hz), 4.08 (1H, br
s), 4.08 (1H, dd, J 10.0 and 1.6 Hz), 4.18 (1H, dd, J
9.2 and 9.2 Hz), 4.25 (1H, dd, J 10.0 and 4.6 Hz), 4.50
(1H, d, J 11.2 Hz), 4.58 (1H, d, J 3.2 Hz), 4.60 (1H, d,
J 12.0 Hz), 4.67 (1H, d, J 12.0 Hz), 4.71 (1H, d, J
12.0 Hz), 4.75–4.87 (4H, m), 4.92 (1H, d, J 12.0 Hz),
5.03 (1H, d, J 10.8 Hz), 5.59 (1H, s), 7.12–7.44 (28H,
m), 7.45–7.53 (2H, m). Anal. Calcd for C55H58O11: C,
73.81; H, 6.53. Found: C, 73.75; H, 6.39.
4.3.34. Methyl 2,3,4-tri-O-benzyl-6-O-(3,4-di-O-benzoyl-
2,6-dideoxy-b-D-arabino-hexopyranosyl)-a-D-glucopyrano-
side (28b). White solid, mp 126.5–128 ꢁC; Rf 0.47 (2:1
28
n-hexane–EtOAc); ½aꢁ ꢀ24.2 (c 0.97, CHCl3); 1H
D
NMR d 1.28 (3H, d, J 6.0 Hz), 1.88 (1H, ddd, J 12.0,
11.0, and 9.4 Hz), 2.40 (1H, dd, J 12.0, 4.4 Hz), 3.37
(3H, s), 3.48–3.68 (4H, m), 3.72–3.82 (1H, m), 4.00
(1H, dd, J 9.0 and 8.8 Hz), 4.08 (1H, br d, J 10.6 Hz),
4.41 (1H, br d, J 9.4 Hz), 4.62 (1H, d, J 3.2 Hz), 4.60
and 4.90 (each 1H, ABq, J 11.2 Hz), 4.65 and 4.79 (each
1H, ABq, J 12.0 Hz), 4.83 and 5.00 (each 1H, ABq, J
10.8 Hz), 5.17 (1H, dd, J 9.2 and 9.2 Hz), 5.28 (1H,
ddd, J 11.0, 9.2, and 4.4 Hz), 7.23–7.45 (19H, m),
7.45–7.56 (2H, m), 7.88–7.99 (4H, m). Anal. Calcd for
C48H50O11: C, 71.80; H, 6.28. Found: C, 71.67; H, 5.96.
4.4.3. Cyclohexylmethyl 2,3-di-O-benzyl-4,6-O-benzylid-
ene-a-D-mannopyranoside (44a). Colorless syrup, Rf
28
0.44 (20:1 toluene–EtOAc); ½aꢁ +48.3 (c 0.94, CHCl3);
D
1H NMR d 0.80–0.98 (2H, m), 1.04–1.32 (3H, m),
1.42–1.78 (6H, m), 3.14 (1H, dd, J 9.0 and 6.0 Hz),
3.43 (1H, dd, J 9.0 and 6.4 Hz), 3.77 (1H, ddd, J 9.6,
9.4, and 4.2 Hz), 3.81 (1H, dd, J 3.0 and 1.2 Hz), 3.88
(1H, dd, J 10.0 and 9.6 Hz), 3.96 (1H, dd, J 9.4 and
3.0 Hz), 4.24 (1H, dd, J 9.4 and 9.4 Hz), 4.25 (1H, dd,
J 10.0 and 4.2 Hz), 4.67 and 4.86 (each 1H, ABq, J
11.6 Hz), 4.73 and 4.83 (each 1H, ABq, J 12.0 Hz),
4.74 (1H, d, J 1.2 Hz), 5.65 (1H, s), 7.23–7.43 (13H,
m), 7.47–7.55 (2H, m). Anal. Calcd for C34H40O6: C,
74.97; H, 7.40. Found: C, 74.95; H, 7.03.
4.4. Glycosidation protocol for the preparation of the b-
mannopyranosides
To a stirred solution of 2,3-di-O-benzyl-4,6-O-benzylid-
ene-a-D-mannopyranosyl diethyl phosphite (7) (a/
b = >99/1, 0.1 mmol) and an alcohol (0.2 mmol) in dry
CH2Cl2 (1 mL) was added montmorillonite K-10
(200 wt % to the glycosyl donor 7). After stirring for
1 h at ꢀ10 ꢁC, the mixture was filtered and the filtrate
was concentrated in vacuo. Purification of the residue
by flash column chromatography gave the mannopyr-
anosides in which b-anomers are major components.
4.4.4. Cyclohexylmethyl 2,3-di-O-benzyl-4,6-O-benzylid-
ene-b-D-mannopyranoside (44b). Colorless syrup, Rf
28
0.40 (20:1 toluene–EtOAc); ½aꢁ ꢀ66.4 (c 0.94, CHCl3);
D
1H NMR d 0.88–1.06 (2H, m), 1.08–1.36 (3H, m),
1.50–1.83 (6H, m), 3.21 (1H, dd, J 9.0 and 6.4 Hz),
3.31 (1H, ddd, J 9.6, 9.2, and 4.6 Hz), 3.57 (1H, dd, J
9.4 and 2.8 Hz), 3.78 (1H, dd, J 9.0 and 6.0 Hz), 3.93
(1H, d, J 2.8 Hz), 3.95 (1H, dd, J 10.0 and 9.6 Hz),
4.22 (1H, dd, J 9.4 and 9.2 Hz), 4.31 (1H, dd, J 10.0
and 4.6 Hz), 4.42 (1H, br s), 4.58 and 4.68 (each 1H,
ABq, J 12.2 Hz), 4.88 and 5.00 (each 1H, ABq, J
12.0 Hz), 5.61 (1H, s), 7.23–7.42 (11H, m), 7.44–7.54
(4H, m). Anal. Calcd for C34H40O6: C, 74.97; H, 7.40.
Found: C, 74.91; H, 7.24.
4.4.1. Methyl 2,3,4-tri-O-benzyl-6-O-(2,3-di-O-benzyl-
4,6-O-benzylidene-a-D-mannopyranosyl)-a-D-glucopyrano-
side (41a). White solid, mp 93.7–95.0 ꢁC; Rf 0.22 (6:1
27
D
1
toluene–EtOAc); ½aꢁ +54.2 (c 0.94, CHCl3); H NMR
d 3.28 (3H, s), 3.34 (1H, dd, J 9.0 and 9.0 Hz), 3.44
(1H, dd, J 9.0 and 3.2 Hz), 3.59 (1H, dd, J 11.0 and
1.2 Hz), 3.67 (1H, ddd, J 9.0, 4.4, and 1.2 Hz),
3.72–3.85 (3H, m), 3.76 (1H, dd, J 11.0 and 4.4 Hz),
3.89 (1H, dd, J 9.4 and 2.6 Hz), 3.97 (1H, dd, J 9.0
and 9.0 Hz), 4.12–4.29 (1H, m), 4.23 (1H, dd, J 9.4
and 9.0 Hz), 4.48 (1H, d, J 10.2 Hz), 4.55 (1H, d, J
3.2 Hz), 4.65 (1H, d, J 12.0 Hz), 4.67 (1H, d, J
11.8 Hz), 4.69 (1H, d, J 12.8 Hz), 4.74–4.83 (4H, m),
4.85 (1H, d, J 1.2 Hz), 4.86 (1H, d, J 12.8 Hz), 4.99
(1H, d, J 10.2 Hz), 5.62 (1H, s), 7.18–7.40 (28H, m),
7.44–7.50 (2H, m). Anal. Calcd for C55H58O11: C,
73.81; H, 6.53. Found: C, 73.75; H, 6.39.
4.4.5. n-Octyl 2,3-di-O-benzyl-4,6-O-benzylidene-a-D-
mannopyranoside (45a). Colorless syrup, Rf 0.46 (20:1
28
D
1
toluene–EtOAc); ½aꢁ +116 (c 0.94, CHCl3); H NMR
d 0.89 (1H, t, J 6.4 Hz), 1.22–1.35 (10H, m), 1.47–1.60
(2H, m), 3.34 (1H, dd, J 9.2 and 6.4 Hz), 3.62 (1H, dd,
J 9.2 and 6.4 Hz), 3.79 (1H, ddd, J 10.2, 9.4, and
4.2 Hz), 3.82 (1H, dd, J 3.0 and 1.2 Hz), 3.88 (1H, dd,
J 10.2 and 9.4 Hz), 3.97 (1H, dd, J 9.6 and 3.0 Hz),
4.24 (1H, dd, J 9.4 and 9.6 Hz), 4.25 (1H, dd, J 9.4

H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
351
and 4.2 Hz), 4.66 and 4.84 (each 1H, ABq, J 11.6 Hz),
4.73 and 4.83 (each 1H, ABq, J 12.0 Hz), 4.77 (1H, d,
J 1.2 Hz), 5.65 (1H, s), 7.23–7.43 (13H, m), 7.48–7.55
(2H, m). Anal. Calcd for C35H44O6: C, 74.97; H, 7.91.
Found: C, 74.92; H, 7.62.
for C30H34O6: C, 73.45; H, 6.99. Found: C, 73.73; H,
6.94.
4.4.10. Isopropyl 2,3-di-O-benzyl-4,6-O-benzylidene-b-D-
mannopyranoside (47b). Colorless syrup, Rf 0.30 (20:1
28
D
1
toluene–EtOAc); ½aꢁ ꢀ76.1 (c 0.45, CHCl3); H NMR
4.4.6. n-Octyl 2,3-di-O-benzyl-4,6-O-benzylidene-b-D-
d 1.16 (3H, d, J 5.6 Hz), 1.28 (3H, d, J 6.0 Hz), 3.32
(1H, ddd, J 9.6, 9.2, and 4.6 Hz), 3.58 (1H, dd, J 9.4
and 2.8 Hz), 3.86 (1H, d, J 2.8 Hz), 3.94 (1H, dd, J 10.0
and 9.6 Hz), 3.98 (1H, septet, J 6.0 Hz), 4.21 (1H, dd, J
9.4 and 9.2 Hz), 4.39 (1H, dd, J 10.0 and 4.6 Hz), 4.54
(1H, br s), 4.58 and 4.67 (each 1H, ABq, J 12.4 Hz),
4.89 and 5.00 (each 1H, ABq, J 12.2 Hz), 5.62 (1H, s),
7.22–7.42 (11H, m), 7.45–7.54 (4H, m). Anal. Calcd for
C30H34O6: C, 73.45; H, 6.99. Found: C, 73.16; H, 6.73.
mannopyranoside (45b). White solid, mp 43.0–44.5 ꢁC;
27
Rf 0.42 (20:1 toluene–EtOAc); ½aꢁ ꢀ70.5 (c 0.84,
D
1
CHCl3), H NMR d 0.89 (1H, t, J 6.4 Hz), 1.24–1.43
(10H, m), 1.57–1.69 (2H, m), 3.32 (1H, ddd, J 9.6, 9.2,
and 4.6 Hz), 3.42 (1H, dd, J 9.0 and 6.4 Hz), 3.58 (1H,
dd, J 9.4 and 2.8 Hz), 3.72 (1H, d, J 2.8 Hz), 3.94 (1H,
dd, J 9.0 and 6.0 Hz), 3.94 (1H, dd, J 10.0 and
9.6 Hz), 4.21 (1H, dd, J 9.4 and 9.2 Hz), 4.31 (1H, dd,
J 10.0 and 4.6 Hz), 4.94 (1H, br s), 4.58 and 4.68 (each
1H, ABq, J 12.2 Hz), 4.88 and 5.00 (each 1H, ABq, J
12.0 Hz), 5.62 (1H, s), 7.24–7.42 (11H, m), 7.44–7.54
(4H, m). Anal. Calcd for C35H44O6: C, 74.97; H, 7.91.
Found: C, 74.94; H, 7.63.
4.4.11. Methyl 4-O-(2,3-di-O-benzyl-4,6-O-benzylidene-
a-D-mannopyranosyl)-2,3-O-isopropylidene-a-L-rhamno-
pyranoside (48a). White solid, mp 131.0–133.0 ꢁC; Rf
27
0.48 (3:1 n-hexane–EtOAc); ½aꢁ +62.8 (c 0.71, CHCl3),
D
1H NMR d 0.96 (3H, d, J 6.2 Hz), 1.31 and 1.49 (each
3H, each s), 3.25 (1H, dd, J 10.0 and 7.0 Hz), 3.33
(3H, s), 3.51 (1H, dq, J 10.0 and 6.2 Hz), 3.78 (1H, d,
J 3.0 Hz), 3.84 (1H, dd, J 10.0 and 9.8 Hz), 3.92 (1H,
dd, J 9.4 and 3.0 Hz), 3.97–4.12 (1H, m), 4.00 (1H, dd,
J 7.0 and 5.4 Hz), 4.06 (1H, d, J 5.4 Hz), 4.24 (1H, dd,
J 9.8 and 5.0 Hz), 4.25 (1H, dd, J 9.4 and 9.0 Hz),
4.67 and 4.87 (each 1H, ABq, J 12.0 Hz), 4.70 and
4.85 (each 1H, ABq, J 12.4 Hz), 4.75 (1H, br s), 4.81
(1H, br s), 5.65 (1H, s), 7.24–7.43 (13H, m), 7.49–7.57
(2H, m). Anal. Calcd for C37H44O10: C, 68.50; H,
6.84. Found: C, 68.18; H, 6.62.
4.4.7. Cyclohexyl 2,3-di-O-benzyl-4,6-O-benzylidene-a-D-
mannopyranoside (46a). Colorless syrup, Rf 0.42 (20:1
28
D
1
toluene–EtOAc); ½aꢁ +54.6 (c 1.88, CHCl3); H NMR
d 1.09–1.43 (5H, m), 1.43–1.60 (1H, m), 1.60–1.87 (2H,
m), 3.47–3.58 (1H, m), 3.78 (1H, dd, J 2.8 and
1.2 Hz), 3.81–3.93 (2H, m), 4.00 (1H, dd, J 9.6 and
2.8 Hz), 4.18–4.32 (2H, m), 4.67 and 4.86 (each 1H,
ABq, J 11.8 Hz), 4.71 and 4.84 (each 1H, ABq, J
12.4 Hz), 4.90 (1H, d, J 1.2 Hz), 5.65 (1H, s), 7.23–
7.43 (13H, m), 7.48–7.55 (2H, m). Anal. Calcd for
C33H38O6: C, 74.69; H, 7.22. Found: C, 74.57; H, 6.95.
4.4.8. Cyclohexyl 2,3-di-O-benzyl-4,6-O-benzylidene-b-D-
mannopyranoside (46b). Colorless syrup, Rf 0.35 (20:1
toluene–EtOAc); ½aꢁ ꢀ70.6 (c 0.41, CHCl3); H NMR
4.4.12. Methyl 4-O-(2,3-di-O-benzyl-4,6-O-benzylidene-
b-D-mannopyranosyl)-2,3-O-isopropylidene-a-L-rhamno-
pyranoside (48b). Colorless syrup, Rf 0.48 (3:1 n-hex-
28
D
1
27
1
d 1.20–1.42 (4H, m), 1.43–1.59 (2H, m), 1.63–1.86 (3H,
m), 1.86–1.98 (1H, m), 3.31 (1H, ddd, J 9.6, 9.0, and
4.6 Hz), 3.58 (1H, dd, J 9.4 and 2.8 Hz), 3.65–3.75
(1H, m), 3.87 (1H, d, J 2.8 Hz), 3.94 (1H, dd, J 10.0
and 9.6 Hz), 4.22 (1H, dd, J 9.4 and 9.0 Hz), 4.30 (1H,
dd, J 10.0 and 4.6 Hz), 4.59 and 4.67 (each 1H, ABq,
J 12.4 Hz), 4.60 (1H, br s), 4.91 and 5.02 (each 1H,
ABq, J 12.2 Hz), 5.62 (1H, s), 7.22–7.42 (11H, m),
7.45–7.54 (4H, m). Anal. Calcd for C33H38O6: C,
74.69; H, 7.22. Found: C, 74.39; H, 7.28.
ane–EtOAc); ½aꢁ ꢀ84.8 (c 0.65, CHCl3); H NMR d
D
1.33 (3H, d, J 5.0 Hz), 1.32 and 1.49 (each 3H, each
s), 3.32 (1H, ddd, J 9.6, 9.2, and 4.6 Hz), 3.39 (3H, s),
3.57–3.73 (2H, m), 3.63 (1H, dd, J 9.6 and 2.8 Hz),
3.95 (1H, dd, J 10.2 and 9.6 Hz), 3.96 (1H, d, J
2.8 Hz), 4.28 (1H, d, J 5.2 Hz), 4.32 (1H, dd, J 6.0 and
5.2 Hz), 4.39 (1H, dd, J 9.6 and 9.2 Hz), 3.97–4.12
(1H, m), 4.00 (1H, dd, J 7.0 and 5.4 Hz), 4.06 (1H, d,
J 5.4 Hz), 4.24 (1H, dd, J 9.8 and 5.0 Hz), 4.25 (1H,
dd, J 9.4 and 9.0 Hz), 4.27 (1H, dd, J 10.2 and
4.6 Hz), 4.60 and 4.68 (each 1H, ABq, J 12.0 Hz), 4.80
and 4.92 (each 1H, ABq, J 11.8 Hz), 4.86 (1H, br s),
4.99 (1H, br s), 5.62 (1H, s), 7.22–7.55 (15H, m). Anal.
Calcd for C37H44O10: C, 68.50; H, 6.84. Found: C,
68.59; H, 6.86.
4.4.9. Isopropyl 2,3-di-O-benzyl-4,6-O-benzylidene-a-D-
mannopyranoside (47a). Colorless syrup, Rf 0.38 (20:1
28
D
1
toluene–EtOAc); ½aꢁ +47.5 (c 1.33, CHCl3); H NMR
d 1.05 (3H, d, J 5.6 Hz), 1.17 (3H, d, J 6.0 Hz), 3.79
(1H, dd, J 2.8 and 1.2 Hz), 3.80–3.92 (3H, m), 3.98
(1H, dd, J 9.6 and 2.8 Hz), 4.17–4.29 (2H, m), 4.67
and 4.85 (each 1H, ABq, J 12.0 Hz), 4.72 and 4.85 (each
1H, ABq, J 12.0 Hz), 4.86 (1H, d, J 1.2 Hz), 5.65 (1H,
s), 7.23–7.43 (13H, m), 7.47–7.55 (2H, m). Anal. Calcd
4.4.13. Methyl 2,3,6-tri-O-benzyl-4-O-(2,3-di-O-benzyl-
4,6-O-benzylidene-a-D-mannopyranosyl)-a-D-glucopyrano-
side (49a). Colorless syrup, Rf 0.27 (8:1 toluene–
28
1
EtOAc); ½aꢁ +13.3 (c 1.15, CHCl3); H NMR d 3.39
D

352
H. Nagai et al. / Carbohydrate Research 340 (2005) 337–353
6. Jyojima, T.; Miyamoto, N.; Ogawa, Y.; Matsumura, S.;
Toshima, K. Tetrahedron Lett. 1999, 40, 5023–5026.
7. (a) Martin, T. J.; Schmidt, R. R. Tetrahedron Lett. 1992,
(3H, s), 3.55 (1H, dd, J 8.4 and 3.0 Hz), 3.44 (1H, dd, J
9.0 and 3.2 Hz), 3.59 (1H, dd, J 11.0 and 1.2 Hz),
3.67–3.89 (6H, m), 3.78 (1H, dd, J 2.8 and 1.2 Hz),
3.83 (1H, dd, J 8.4 and 8.4 Hz), 3.92 (1H, dd, J 9.2
and 2.8 Hz), 4.06–4.13 (1H, m), 4.20 (1H, d, J
11.2 Hz), 4.22 (1H, dd, J 9.2 and 8.8 Hz), 4.31 (1H, d,
J 11.2 Hz), 4.34–4.64 (5H, m), 4.42 (1H, d, J 11.2 Hz),
4.68 (1H, d, J 11.6 Hz), 4.80 (1H, d, J 12.0 Hz), 5.09
(1H, d, J 11.2 Hz), 5.30 (1H, d, J 1.2 Hz), 5.60 (1H, s),
7.10–7.17 (2H, m), 7.17–7.41 (26H, m), 7.45–7.53 (2H,
m). Anal. Calcd for C55H58O11: C, 73.81; H, 6.53.
Found: C, 73.73; H, 6.33.
33, 6123–6126; (b) Muller, T.; Schneider, R.; Schmidt, R.
¨
R. Tetrahedron Lett. 1994, 35, 4763–4766.
8. (a) Kondo, H.; Ichikawa, Y.; Wong, C.-H. J. Am. Chem.
Soc. 1992, 114, 8748–8750; (b) Sim, M. M.; Kondo, H.;
Wong, C.-H. J. Am. Chem. Soc. 1993, 115, 2260–2267; (c)
Kondo, H.; Aoki, S.; Ichikawa, Y.; Halcomb, R. L.;
Ritzen, H.; Wong, C.-H. J. Org. Chem. 1994, 59, 864–877.
9. (a) Watanabe, Y.; Nakamoto, C.; Ozaki, S. Synlett 1993,
115–116; (b) Watanabe, Y.; Nakamoto, C.; Yamamoto,
T.; Ozaki, S. Tetrahedron 1994, 50, 6523–6536.
10. (a) Hashimoto, S.; Umeo, K.; Sano, A.; Watanabe, N.;
Nakajima, M.; Ikegami, S. Tetrahedron Lett. 1995, 36,
2251–2254; (b) Hashimoto, S.; Sano, A.; Sakamoto, H.;
Nakajima, M.; Yanagiya, Y.; Ikegami, S. Synlett 1995,
1271–1273; (c) Tanaka, H.; Sakamoto, H.; Nakamura, S.;
Nakajima, M.; Hashimoto, S. Chem. Commun. 1999,
1259–1260; (d) Sakamoto, H.; Nakamura, S.; Tsuda, T.;
Hashimoto, S. Tetrahedron Lett. 2000, 41, 7691–7695; (e)
Tsuda, T.; Sato, S.; Nakamura, S.; Hashimoto, S.
Heterocycles 2003, 59, 509–515.
11. (a) Schene, H.; Waldmann, H. Eur. J. Org. Chem. 1998,
1227–1230; (b) Schene, H.; Waldmann, H. Synthesis 1999,
1411–1422.
12. (a) Nagai, H.; Matsumura, S.; Toshima, K. Tetrahedron
Lett. 2002, 43, 847–850; (b) Nagai, H.; Matsumura, S.;
Toshima, K. Chem. Lett. 2002, 1100–1101; (c) Nagai, H.;
Matsumura, S.; Toshima, K. Carbohydr. Res. 2003, 338,
1531–1534.
4.4.14. Methyl 2,3,6-tri-O-benzyl-4-O-(2,3-di-O-benzyl-
4,6-O-benzylidene-b-D-mannopyranosyl)-a-D-glucopyrano-
side (49b). Colorless syrup, Rf 0.43 (8:1 toluene–
28
D
1
EtOAc); ½aꢁ ꢀ26.4 (c 1.50, CHCl3); H NMR d 3.04
(1H, ddd, J 9.2, 9.0, and 4.6 Hz), 3.32 (1H, dd, J 9.2
and 2.6 Hz), 3.40 (3H, s), 3.42–3.66 (4H, m), 3.45 (1H,
dd, J 10.0 and 2.6 Hz), 3.63 (1H, d, J 2.6 Hz),
3.81–3.93 (2H, m), 3.75 (1H, ddd, J 9.6, 4.6, and
1.6 Hz), 4.04 (1H, dd, J 10.0 and 4.6 Hz), 4.07 (1H,
dd, J 9.2 and 9.0 Hz), 4.28 (1H, d, J 11.6 Hz), 4.37
(1H, br s), 4.54–4.67 (4H, m), 4.70–4.86 (5H, m) 5.05
(1H, d, J 10.4 Hz), 5.51 (1H, s), 7.15–7.42 (28H, m),
7.44–7.51 (2H, m). Anal. Calcd for C55H58O11: C,
73.81; H, 6.53. Found: C, 73.76; H, 6.44.
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Acknowledgements
This research was supported in part by Grant-in-Aid for
the 21st Century COE program ÔKEIO Life Conjugate
ChemistryÕ from the Ministry of Education, Culture,
Sports, Science, and Technology, Japan.
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