2′-Carboxybenzyl glycosides: glycosyl donors for C-glycosylation and conversion into other glycosyl donors

Article abstract of DOI:10.1016/j.carres.2006.03.014

Glycosylation of various glycosyl acceptors with 2′-carboxybenzyl (CB) 2,3,4,6-tetra-O-benzyl-β-d-glucopyranoside and CB 2,3,4,6-tetra-O-benzyl-α-d-mannopyranoside as glycosyl donors afforded α-C-glycosides exclusively or predominantly in good yields. CB

Full text of DOI:10.1016/j.carres.2006.03.014

Carbohydrate Research 341 (2006) 1708–1716
Note
20-Carboxybenzyl glycosides: glycosyl donors for C-glycosylation
and conversion into other glycosyl donors
Yong Joo Lee, Ju Yuel Baek, Bo-Young Lee, Sung Soo Kang, Hye-Seo Park,
Heung Bae Jeon* and Kwan Soo Kim*
Center for Bioactive Molecular Hybrids and Department of Chemistry, Yonsei University, Seoul 120-749, Republic of Korea
Received 1 February 2006; received in revised form 8 March 2006; accepted 13 March 2006
Available online 17 April 2006
Abstract—Glycosylation of various glycosyl acceptors with 20-carboxybenzyl (CB) 2,3,4,6-tetra-O-benzyl-b-D-glucopyranoside and
CB 2,3,4,6-tetra-O-benzyl-a-D-mannopyranoside as glycosyl donors afforded a-C-glycosides exclusively or predominantly in good
yields. CB glycosides were also converted to other well-known glycosyl donors, the corresponding phenyl thioglycoside and the gly-
cosyl fluoride derivatives.
Ó 2006 Elsevier Ltd. All rights reserved.
Keywords: C-glycosylation; C-glycosides; CB glycosides; Glycosyl donors
The development of efficient and stereospecific C-glycos-
ylation methodologies has become an increasingly
attractive area in synthetic organic chemistry due to
the discovery of novel classes of antitumor compounds,
such as aquayamycin1 and pluramycin,2 and of anti-
biotic compounds, such as chrysomycin,3 ravidomycin,4
and vineomycin,5 possessing C-aryl glycosides as well
as a wide variety of medicinally important C-nucleo-
sides.6 The absence of an oxygen atom between the car-
bohydrate and the aglycon moiety results in greater
stability of these compounds as they are resistant to
chemical and enzymatic hydrolysis compared to O-gly-
cosides. C-glycosides are thus hydrolytically stable car-
bohydrate mimetics with many possible biological
applications.7
donors. For example, several C-glycosylation methodol-
ogies based on efficient glycosyl donors, such as glycosyl
fluorides,9 glycosyl trichloroacetimidates,10 glycals,11
lactones,12 thioglycosides,13 and glycosyl phosphates,14
have been employed. Nevertheless, there still remains a
need for more study on C-glycosylation methods with
respect to stereoselectivity, yields and reaction time.
In our previous endeavors, we reported a novel type
of glycosyl donors, 20-carboxybenzyl (CB) glycosides B
(Fig. 1) that are useful for stereoselective b-mannopyr-
anosylation,15 2-deoxyglucopyranosylation,16 b-arabino-
furanosylation,17 and are also very effective for the
synthesis of complex oligosaccharides by the latent-
active glycosylation strategy.17,18 The CB glycoside
B was prepared from 20-(benzyloxycarbonyl)benzyl
(BCB) glycoside A by the selective removal of its benzyl
ester functionality. Treatment of B with DTBMP and
triflic anhydride followed by the spontaneous lactoniza-
tion of the resulting glycosyl triflate D would afford the
oxocarbenium ion E by extrusion of stable phthalide.
Reaction of E with the glycosyl acceptor (nucleophile)
would give the desired glycoside F. Herein we report a
new method for the C-glycosylation using CB glycosides
as glycosyl donors. To explore further the scope of this
CB glycoside method, we also converted them to other
To date several different approaches for the synthesis
of C-glycosides have been explored.8 The most common
method for the carbon–carbon bond formation at the
anomeric carbon involves the attack of a carbon nucleo-
phile on the electrophilic anomeric center of glycosyl
*
Corresponding authors. Tel.: +82 2 2123 2640/7615; fax: +82 2 365
7608 (K.S.K.); e-mail addresses: hbj@yonsei.ac.kr; kwan@yonsei.
ac.kr
0008-6215/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2006.03.014

Y. J. Lee et al. / Carbohydrate Research 341 (2006) 1708–1716
1709
O
O
O
DTBMP
O
O
O
O
O
O
O-
OBn
OH
C
A (BCB glycoside)
B (CB glycoside)
Tf2O
O
O
O
O
+
O
Nu
O
O
OTf
Nu
OTf
F
E
D
Figure 1.
˚
well-known glycosyl donors: thioglycosides and glycosyl
fluorides.
of 4 A molecular sieves for 20 min at room temperature
in CH2Cl2 (10 mL), (ii) addition of Tf2O (1.2 equiv) to
this solution at ꢀ78 °C and stirring the reaction mixture
for 10 min, (iii) addition of the glycosyl acceptor
(2.0 equiv) and stirring the reaction mixture for another
1 h at ꢀ78 °C and allowing the solution to warm over
1 h to 0 °C, and (iv) quenching the reaction by the addi-
tion of aqueous NaHCO3. Glycosylations of acceptors,
1,3,5-trimethoxybenzene (5) and 1,3-dimethoxybenzene
(6) with the donor 3 afforded exclusively a-C-glycosides
10 and 11 in 66% and 68% yields, respectively, along
with the self-condensed ester 15 (Fig. 2) in 26% yields
in both cases (Table 1, entries 1 and 2), whereas the
CB tetrabenzylglucoside 3 was prepared by the selec-
tive hydrogenolysis of BCB tetrabenzylglucoside 2,
which was obtained from BCB glucoside 1 by the known
procedure (Scheme 1).18b The CB tetrabenzylmannoside
4 was prepared in a similar manner.
For our initial studies, C-glycosylations of various
glycosyl acceptors (5–9) with the CB tetrabenzylgluco-
side 3 were carried out by the following standard reac-
tion protocol (Scheme 2, method A): (i) stirring the
solution of 3 (100 mg, 1.0 equiv) and 2,6-di-tert-butyl-
4-methylpyridine (DTBMP, 2.4 equiv) in the presence
HO
HO
BnO
BnO
BnO
a
b
O
O
O
BnO
BnO
OBCB
OCB
OBCB
HO
BnO
HO
BnO
BnO
1
2
3
BnO
BnO
OBn
O
CH2
O
CH2
O
BCB =
CB =
OBn
OH
BnO
OCB
4
Scheme 1. Reagents and conditions: (a) NaH, BnBr, DMF, rt, 2 h, 80%; (b) H2, Pd/C, NH4OAc, CH3OH, rt, 1 h, 94%.
OMe
BnO
O
BnO
MeO
OMe
BnO
Tf2O
5
BnO
MeO
DTBM P
4A MS
CH2Cl2
+
15
26%
Method A
Method B
3
OMe
-78 oC
-78 oC to 0 o
1 h
C
OMe
10
66%
Tf2O
-78 oC
3
DTBMP
4A MS
CH2Cl2
5
10
76%
+
15
15%
-78 oC, 1 h
Scheme 2. Glycosylation of acceptor 5 with CB glycoside 3.

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Y. J. Lee et al. / Carbohydrate Research 341 (2006) 1708–1716
BnO
OBn
O
BnO
BnO
O
BnO
O
O
BnO
O
BnO
O
BnO
O
BnO
OBn
OBn
OBn
OBn
O
O
O
BnO
OBn
OBn
21
15
Figure 2.
Table 1. C-glycosylations with the CB glucoside 3 as the glycosyl donor
Entry
Glycosyl acceptor
C-glycoside
Methoda
Yield (%)b
Ratio (a/b)b
Self-condensed
ester 15 (%)b
1
5
10
A
B
66
76
a only
a only
26
15
BnO
O
BnO
BnO
OMe
BnO
OMe
2
3
4
5
A
B
68
79
a only
a only
26
12
MeO
6
OMe
11
BnO
Me
O
Me
N
BnO
BnO
Me
N
BnO
A
B
63
85
1.7:1
1.7:1
30
0
Me
7
12
BnO
O
BnO
O
BnO
A
B
56
73
a only
a only
39
20
BnO
O
8
13
BnO
O
BnO
BnO
TMS
A
B
56
68
a only
a only
36
20
BnO
9
14
a Method A: The acceptor was added to a solution of the donor (CB glycoside), DTBMP, and Tf2O. Method B: The donor (CB glycoside) was added
to a solution of the acceptor, DTBMP, and Tf2O. See the text or experimental for details.
b Determined after isolation.
reaction of 3 with 1,2-dimethylindole (7) gave a mixture
of a- and b-C-glycoside 12 (a/b = 1.7:1) in 63% yield
(entry 3). On the other hand, the same reaction of 3 with
the acceptors furan (8) and allyltrimethylsilane (9) pro-
vided a-C-glycosides 13 and 14 exclusively in 56% yields
in both cases, along with the ester 15 in 39% and 36%
yields, respectively (entries 4 and 5).
of the ester 15, we ran the glycosylation reaction with
the reversal of the order of the addition of reactants.
Thus, C-glycosylations of acceptors 5–9 with the CB tet-
rabenzylglucoside 3 were carried out under the modified
reaction conditions: (Scheme 2, method B): (i) stirring
the solution of the glycosyl acceptor (2.0 equiv) and
˚
DTBMP (2.4 equiv) in the presence of 4 A molecular
Formation of the self-condensed ester 15 probably
resulted from the coupling between the carboxylate
anion C, which was generated by deprotonation of the
CB glycoside B by DTBMP, and the oxocarbenium
ion E as shown in Figure 1. To suppress the formation
sieves for 20 min at room temperature in CH2Cl2
(5 mL), (ii) addition of Tf2O (1.2 equiv) to this solution
at ꢀ78 °C, (iii) dropwise addition of 3 (100 mg, 1.0
equiv) in CH2Cl2 (5 mL) to the solution over a period
of 10 min and stirring the reaction mixture for further

Y. J. Lee et al. / Carbohydrate Research 341 (2006) 1708–1716
1711
1 h at ꢀ78 °C, and (iv) quenching the reaction by the
addition of aqueous NaHCO3. Under the modified reac-
tion condition (method B), glycosylations of the accep-
tors 5, 6, 8, and 9 with the donor 3 afforded only a-C-
glycosides 10, 11, 13, and 14, respectively, in 68–79%
yields, along with the ester 15 in 12–20% yields (Table
1, entries 1, 2, 4, and 5). In particular, although the same
reaction of 3 with 7 gave a mixture of a- and b-C-glyco-
side 12 (a/b = 1.7:1), the yield was increased to 85%,
without generation of the ester 15 (entry 3). Clearly,
the modified reaction condition, method B, reduced
the formation of the self-condensed ester 15 and
increased the yield of C-glycosylation reaction. It is wor-
thy of note that reactions of the CB tetrabenzylglucoside
3 with acceptors 5, 6, 8, and 9 afforded the correspond-
ing a-C-glycosides exclusively using both reaction
conditions.
donor, we also performed C-glycosylation of the glyco-
syl acceptors 5–9 with CB tetrabenzylmannoside 4 under
method B conditions (Table 2). Glycosylation of 5–8
with 4 under method B afforded a-C-glycosides 16–19
exclusively in 52–74% yields, along with the self-con-
densed ester 21 (Fig. 2) in 18–28% yields (entries 1–4).
On the other hand, the same reaction of 4 with acceptor
9 provided a mixture of a- and b-C-glycoside 20 (a/b =
3:1) in 55% yield (entry 5).
It is interesting to note that the values of proton cou-
3
3
pling constants, JH1–H2 and JH3–H4 of compound 16
are 8.8 and 4.7 Hz, respectively. These coupling constant
values suggest that the pyranose ring of the compound
16, which has a trimethoxyphenyl group at C-1, favors
the 1C4 conformation rather than the 4C1 conforma-
tion.19 A 2D-NOESY spectrum (sm = 550 ms) also
supported the 1C4 conformation of 16 (entry 1).
Thus, strong NOEs were observed between H1 and
H6, and between H1 and protons of the C6-O-benzyl
group.
Because the modified reaction condition (method B)
resulted in the improved yields for the C-glycoside in
case of the CB tetrabenzylglucoside 3 as a glycosyl
Table 2. C-glycosylations with the CB mannoside 4 as the glycosyl donor under modified condition (Method B)a
Entry
Acceptor
C-glycoside
Yield (%)b
Ratio (a/b)b
Self-condensed
ester 21 (%)b
BnO
OBn
MeO
OBn
O
1
5
69
a only
21
OMe
OBn
MeO
16
BnO
BnO
OBn
O
BnO
OMe
2
6
71
a only
24
OMe
17
OBn
O
BnO
BnO
BnO
3
7
52
a only
28
Me
N
Me
18
BnO
OBn
O
BnO
BnO
4
5
8
9
74
55
a only
18
20
O
19
BnO
OBn
O
BnO
BnO
3:1
20
a Method B: The donor (CB glycoside) was added to a solution of acceptor, DTBMP, and Tf2O. See the text or experimental for details.
b Determined after isolation.

1712
Y. J. Lee et al. / Carbohydrate Research 341 (2006) 1708–1716
BnO
BnO
BnO
OBn
O
OBn
O
a
b
BnO
4
BnO
BnO
SPh
F
23
24
82%
91%
(α/β = 1:4)
(α/β = 1:2)
OBn
O
OBn
OBn
Ph
O
BnO
a
Ph
Ph
O
BnO
O
BnO
b
O
O
O
O
O
SPh
F
OCB
26
91%
25
85%
22
˚
Scheme 3. Reagents and conditions: (a) 4 or 22, DTBMP, Tf2O, 4 A molecular sieves, CH2Cl2, ꢀ78 °C, 10 min, then PhSH, ꢀ78 °C to 0 °C, 2 h; (b) 4
˚
or 22, DTBMP, Tf2O, 4 A molecular sieves, CH2Cl2, ꢀ78 °C, 10 min, then DAST, ꢀ78 °C to 0 °C, 2 h.
Besides the C-glycosylation, we attempted to convert
the CB mannopyranosides 4 and 2215 to other well-
known glycosyl donors, for example, thioglycosides
and glycosyl fluorides (Scheme 3). Frequently, the con-
version between glycosyl donors is very useful in the
synthesis of complex oligosaccharides because a specific
glycosyl donor gives higher stereoselectivity and better
yield for a certain glycosylation reaction. The conver-
sion of CB glycosides into thioglycosides and glycosyl
fluorides was carried out under the standard reaction
conditions (method A). The reaction of 4 with PhSH
afforded a mixture of a- and b-phenyl thioglycosides,
23 in 82% yield (a/b = 1:4), and the same reaction with
(diethylamino)sulfur trifluoride (DAST) as a fluoride
source also provided a mixture of a- and b-glycosyl fluo-
ride 24 in 91% yield (a/b = 1:2). On the other hand, the
reaction of CB 4,6-benzylidenemannopyranoside 22
with PhSH and with DAST gave the previously
unknown b-phenyl thioglycoside 25 and b-glycosyl
fluoride 26 exclusively in 85% or 92% yield, respectively.
It is probable that the exclusive b-stereoselectivity in
these reactions is due to the formation of a highly
reactive 4,6-O-benzylidenemannopyranosyl a-triflate20
intermediate at low temperature as in the case of our
previous b-O-mannopyranosylation.15
otherwise noted. All reagents were purchased from com-
mercial suppliers and used without further purification
unless otherwise noted. Flash column chromatography
was performed employing 230–400 mesh silica gel.
Thin-layer chromatography was performed using Silica
Gel 60 F254 precoated plates (0.25 mm thickness) with
a fluorescent indicator. NMR spectra were recorded
on a Bruker 250, 400, or 500 MHz NMR spectrometer.
Chemical shifts are reported in parts per million (ppm)
downfield from tetramethylsilane (TMS) unless other-
wise noted. Optical rotations were measured with a
Rudolph Autopol III automatic polarimeter.
1.2. Typical experimental protocol for the glycosylation
reaction
1.2.1. Method A. A solution of glycosyl donor 3
(100 mg, 0.15 mmol) and DTBMP (74 mg, 0.36 mmol)
˚
in CH2Cl2 (10 mL) in the presence of 4 A molecular
sieves (500 mg) was stirred for 20 min at rt and cooled
to ꢀ78 °C, then Tf2O (30 lL, 0.18 mmol) was added.
After the resulting solution was stirred at ꢀ78 °C for
10 min, glycosyl acceptor (0.30 mmol) was added and
stirred at ꢀ78 °C for 1 h and allowed to warm over
1 h to 0 °C. The reaction mixture was quenched by the
addition of satd aq NaHCO3 and then extracted with
CH2Cl2. The combined organic layer was washed with
satd aq NaHCO3 and brine, dried over MgSO4, and
concentrated in vacuo. The residue was purified by flash
column chromatography (3:1, hexane/EtOAc) to afford
the desired C-glycoside.
In conclusion, we have developed a highly stereoselec-
tive method for the synthesis of C-glycosides by employ-
ing CB glycosides 3 and 4 as glycosyl donors.
C-glycosylations of various glycosyl acceptors with
donors, 3 and 4 afforded exclusively or predominantly
a-C-glycosides in good yields. In addition, CB glyco-
sides 4 and 22 were successfully converted to well-
known glycosyl donors, thioglycosides and glycosyl
fluorides in excellent yields.
1.2.2. Method B. A solution of glycosyl acceptor
(0.30 mmol) and DTBMP (74 mg, 0.36 mmol) in
˚
CH2Cl2 (5 mL) in the presence of 4 A molecular sieves
1. Experimental
(500 mg) was stirred for 20 min at rt and cooled to
ꢀ78 °C, then Tf2O (30 lL, 0.18 mmol) was added. To
the resulting solution was added dropwise a solution
of glycosyl donor 3 or 4 (100 mg, 0.15 mmol) in CH2Cl2
(5 mL) over 10 min. After stirring at ꢀ78 °C for 1 h, the
reaction mixture was quenched by the addition of satd
1.1. General methods
All reactions were conducted under a positive pressure
of dry argon with dry, freshly distilled solvents unless

Y. J. Lee et al. / Carbohydrate Research 341 (2006) 1708–1716
1713
aq NaHCO3, and then extracted with CH2Cl2. The com-
1.5. 1-(20,30,40,60-tetra-O-benzyl-a-D-mannopyranosyl)-
2,4-dimethoxybenzene (17)
bined organic layer was washed with satd aq NaHCO3
and brine, dried over MgSO4, and concentrated in
vacuo. The residue was purified by flash column chro-
matography (3:1, hexane/EtOAc) to afford the desired
C-glycoside.
Colorless oil, Rf = 0.5 (2:1, hexane/EtOAc); [a]D +12.7
1
(c 1.3, CHCl3); H NMR (250 MHz, CDCl3): d 3.68
(s, 3H, OCH3), 3.79 (s, 3H, OCH3), 3.81–3.93 (m, 4H,
H-3, H-4, H-6a, H-6b), 4.14 (d, 1H, J = 10.5, 5.4 Hz,
H-5), 4.23 (dd, 1H, J = 6.2, 2.7 Hz, H-2), 4.46 (s, 2H,
PhCH2), 4.50–4.64 (m, 6H, 3PhCH2), 5.32 (d, 1H,
J = 6.2 Hz, H-1), 6.40–6.47 (m, 2H, H-30, H-50), 7.06–
7.32 (m, 21H, Ar-H, H-60); 13C NMR (63 MHz, CDCl3):
d 55.5 (2C, OCH3), 69.3 (2C), 71.8, 72.5, 73.0, 73.3,
75.35, 75.38, 76.4, 77.3, 98.8 (C-30), 104.4 (C-50), 120.0
(C-10), [127.4, 127.5, 127.6, 127.7, 127.8 (2C), 127.9
(4C), 128.0 (2C), 128.2 (2C), 128.4 (4C), 128.5 (2C),
129.1 (Ar-C, C-60)], [138.5, 138.69, 138.7, 138.8 (Ar-C
ipso)], [158.5, 160.5 (C-20, C-40)]. Anal. Calcd for
C42H44O7: C, 76.34; H, 6.71. Found: C, 76.37; H, 6.71.
All known compounds, 10,13b 11,13b 12b,10c 13,10c
1
14,14b 15,18b gave acceptable H NMR and 13C NMR
spectra that matched data reported previously.
1.3. 1,2-Dimethyl-3-(20,30,40,60-tetra-O-benzyl-a-D-
glucopyranosyl)-indole (12a)
Colorless oil, Rf = 0.20 (10:1:2, hexane/EtOAc/
CH2Cl2); [a]D +8.7 (c 0.9, CHCl3); 1H NMR (400
MHz, CDCl3): d 2.42 (s, 3H, CH3), 3.62 (s, 3H,
NCH3), 3.62–3.68 (m, 2H, H-6a, H-6b), 3.75–3.80 (m,
1H, H-5), 3.89–3.93 (m, 2H, H-2, H-4), 4.19 (t, 1H,
J = 7.0 Hz, H-3), 4.37 and 4.46 (ABq, 2H, J =
11.6 Hz, PhCH2), 4.42 and 4.57 (ABq, 2H,
J = 12.2 Hz, PhCH2), 4.54 and 4.79 (ABq, 2H, J =
11.2 Hz, PhCH2), 4.75 and 4.87 (ABq, 2H,
J = 11.2 Hz, PhCH2), 5.55 (d, 1H, J 4.4 Hz, H-1),
7.03–7.35 (m, 23H, Ar-H), 7.90 (d, 1H, J = 8.0 Hz,
Ar-H); 13C NMR (100 MHz, CDCl3): d 11.9 (CH3),
29.5 (NCH3), 69.9, 70.9, 72.8, 73.2, 73.5, 74.0, 74.3,
77.8, 81.5, 83.0, 108.0 (C0-8), 108.5 (C0-3), [119.2,
120.5, 120.8 (C0-5, C0-6, C0-7)], [127.3, 127.5, 127.6,
127.7, 127.8, 127.9 (2C), 127.97 (2C), 128.0 (2C), 128.2
(2C), 128.22 (2C), 128.4 (2C), 128.44 (2C), 128.6
(2C)(Ar-C)], [136.3, 136.8 (C0-4, C0-9)], [138.4, 138.5,
138.7, 138.74 (Ar-C ipso)].
1.6. 1,2-Dimethyl-3-(20,30,40,60-tetra-O-benzyl-a-D-
mannopyranosyl)-indole (18)
Colorless oil, Rf = 0.30 (10:1:2, hexane/EtOAc/CH2-
Cl2); [a]D +2.2 (c 0.8, CHCl3); 1H NMR (400 MHz,
CDCl3): d 2.33 (s, 3H, CH3), 3.59 (s, 3H, NCH3),
3.58–3.62 (m, 1H, H-5), 3.80–3.88 (m, 4H, H-2, H-3,
H-6a, H-6b), 4.16 (t, 1H, J = 9.6 Hz, H-4), 4.14 and
4.48 (ABq, 2H, J = 11.2 Hz, PhCH2), 4.59 and 4.71
(ABq, 2H, J = 12.4 Hz, PhCH2), 4.68 and 4.96 (ABq,
2H, J = 10.8 Hz, PhCH2), 4.70 (s, 2H, PhCH2), 4.83
(br s, 1H, H-1), 6.89–7.34 (m, 23H, Ar-H), 7.63 (d,
1H, J = 8.0 Hz, Ar-H); 13C NMR (100 MHz, CDCl3):
d 11.6 (CH3), 29.4 (NCH3), 69.9, 72.2, 73.5, 74.9, 75.3,
75.4, 76.2, 78.2, 80.3, 84.8, 108.4 (C0-8), 108.5 (C0-3),
[119.0, 119.3, 120.5 (C0-5, C0-6, C0-7)], [126.8, 127.1
(2C), 127.4 (2C), 127.66 (2C), 127.7 (2C), 127.8 (2C),
128.2 (2C), 128.22 (2C), 128.4 (2C), 128.47 (2C), 128.5
(2C)(Ar-C)], [134.6, 136.6 (C0-4, C0-9)], [138.76, 138.85,
138.9, 139.0 (Ar-C ipso)]. Anal. Calcd for C44H45NO5:
C, 79.13; H, 6.79; N, 2.10. Found: C, 78.88; H, 7.04;
N, 1.93.
1.4. 1-(20,30,40,60-tetra-O-benzyl-a-D-mannopyranosyl)-
2,4,6-trimethoxybenzene (16)
Colorless oil, Rf = 0.2 (3:1, hexane/EtOAc); [a]D +1.3 (c
1.4, CHCl3); 1H NMR (500 MHz, CDCl3): d 3.69 (s, 6H,
2OCH3), 3.78–3.80 (m, 1H, H-4), 3.80 (s, 3H, OCH3),
3.85 (dd, 1H, J = 10.0, 6.0 Hz, H-6a), 3.94 (dd, 1H,
J = 10.0, 6.8 Hz, H-6b), 4.02–4.04 (dd, 1H, J = 3.5,
4.7 Hz, H-3), 4.02–4.23 (m, 1H, H-5), 4.34 (s, 2H,
PhCH2), 4.49 (d, 1H, J = 12.0 Hz, PhCHH), 4.50 (d,
1H, J = 12.0 Hz, PhCHH), 4.55–4.60 (m, 3H,
3PhCHH), 4.65 (dd, 1H, J = 9.0, 3.3 Hz, H-2), 4.72 (d,
1H, J = 12.5 Hz, PhCHH), 5.56 (d, 1H, J = 8.8 Hz, H-
1), 6.10 (s, 2H, H-30, H-50), 7.06–7.32 (m, 20H, Ar-H);
13C NMR (125 MHz, CDCl3): d 55.4 (OCH3), 56.0
(2C, OCH3), 65.0, 69.0, 71.7, 71.8, 72.7, 73.4, 74.5,
75.4, 75.8, 76.0, 91.3 (2C, C-30, C-50), 108.7 (C-10),
[127.3, 127.4, 127.5 (2C), 127.7 (4C), 127.88 (2C),
127.9 (2C), 128.1 (2C), 128.3 (6C)(Ar-C)], [138.8,
138.87, 138.9, 139.0 (Ar-C ipso)], [160.6(2), 161.2 (C-20,
C-40, C-60)]. Anal. Calcd for C43H46O8: C, 74.76; H,
6.71. Found: C, 74.73; H, 6.72.
1.7. 2-(20,30,40,60-tetra-O-benzyl-a-D-mannopyranosyl)-
furan (19)
Colorless oil, Rf = 0.43 (4:1, hexane/EtOAc); [a]D +3.4
1
(c 3.5, CHCl3); H NMR (400 MHz, CDCl3): d 3.72–
3.82 (m, 3H, H-5, H-6a, H-6b), 3.84 (dd, 1H, J = 8.0,
3.2 Hz, H-3), 4.00 (t, 1H, J = .0 Hz, H-4), 4.16 (t, 1H,
J = 3.2 Hz, H-2), 4.51 (d, 1H, J = 10.8 Hz, PhCHH),
4.54 (d, 1H, J = 12.0 Hz, PhCHH), 4.61–4.80 (m, 6H,
3PhCH2), 5.12 (d, 1H, J = 3.2 Hz, H-1), 6.12 (d, 1H,
J = 3.6 Hz, H0-3), 6.28 (dd, 1H, J = 3.6, 2.0 Hz, H0-4),
7.18–7.36 (m, 21H, Ar-H, H0-5); 13C NMR (100 MHz,
CDCl3): d 69.3, 70.5, 72.2, 72.4, 73.4, 74.6, 74.76, 74.8,
75.0, 79.1 (C-1), [108.9, 110.5 (C0-3, C0-4)], [127.55,

1714
Y. J. Lee et al. / Carbohydrate Research 341 (2006) 1708–1716
127.6, 127.72, 127.74, 127.8, 127.9, 128.0 (2C), 128.06
(2C), 128.13 (2C), 128.2 (2C), 128.38 (2C), 128.44
(2C), 128.5 (2C)(Ar-C)], [138.3, 138.4(2), 138.5 (Ar-C
ipso)], 142.3 (C0-5), 151.2 (C0-2). Anal. Calcd
for C38H38O6: C, 77.26; H, 6.48. Found: C, 77.39; H,
6.45.
80.2, 92.3 (C0-1), 98.0 (C-1), [127.6 (2C), 127.7 (4C),
127.8 (5C), 127.87 (3C), 127.89 (3C), 127.91, 127.92,
127.97, 128.0, 128.07, 128.1 (2C), 128.2 (2C), 128.3
(2C), 128.39 (2C), 128.43, 128.45 (2C), 128.46 (2C),
128.48 (3C), 128.52 (3C), 128.54 (3C)(Ar-C)], [130.8,
133.2, 138.0, 138.1, 138.35, 138.4, 138.5, 138.6 (2C),
141.4 (Ar-C ipso)], 164.1 (C@O). Anal. Calcd
for C76H76O13: C, 76.23; H, 6.40. Found: C, 76.32; H,
6.23.
1.8. 3-(20,30,40,60-tetra-O-benzyl-D-mannopyranyl)-
propene (20)
Compound 20a: colorless oil, Rf = 0.4 (8:1:10, hexane/
EtOAc/CH2Cl2); [a]D +16.7 (c 2.7, CHCl3); H NMR
1.10. Phenyl 2,3,4,6-tetra-O-benzyl-1-thio-D-manno-
pyranoside (23)
1
(500 MHz, CDCl3): d 2.30–2.36 (m, 2H, H0-1a, H0-1b),
3.61–3.62 (m, 1H, H-3), 3.70 (dd, 1H, J = 10.1, 3.0 Hz,
H-6a), 3.75–3.88 (m, 4H, H-1, H-2, H-4, H-6b), 4.05
(dd, 1H, J = 11.4, 6.5 Hz, H-5), 4.50–4.73 (m, 8H,
4PhCH2), 4.99–5.03 (m, 2H, H0-3a, H0-3b), 5.70–5.78
(m, 1H, H0-2), 7.18–7.36 (m, 20H, Ar-H); 13C NMR
(125 MHz, CDCl3): d 34.7 (C0-1), 69.1, 71.5, 72.0,
72.4, 73.3, 73.6, 74.0, 74.8, 74.9, 76.9, 117.4 (C0-3),
[127.6, 127.8 (4C), 128.0 (3C), 128.1 (4C), 128.4 (4C),
128.5 (4C)(Ar-C)], 134.3 (C0-2), [138.2 (3C), 138.4 (Ar-
C ipso)]. Anal. Calcd for C37H40O5: C, 78.69; H, 7.14.
Found: C, 78.70; H, 7.13. Compound 20b: colorless
oil, Rf = 0.5 (8:1:10, hexane/EtOAc/CH2Cl2); [a]D
A solution of 4 (158 mg, 0.23 mmol) and DTBMP
(115 mg, 0.56 mmol) in CH2Cl2 (15 mL) in the presence
˚
of 4 A molecular sieves was stirred for 20 min at rt and
cooled to ꢀ78 °C, then Tf2O (47 lL, 0.28 mmol) was
added. After the resulting solution was stirred at
ꢀ78 °C for 10 min, benzenethiol (36 lL, 0.35 mmol)
was added and stirred at ꢀ78 °C for 1 h and allowed
to warm over 1 h to 0 °C. The reaction mixture was
quenched with satd aq NaHCO3, and then extracted
with CH2Cl2. The combined organic layer was washed
with satd aq NaHCO3 and brine, dried over MgSO4,
and concentrated in vacuo. The residue was purified
by flash column chromatography (7:1, hexane/EtOAc)
to afford a-thioglycoside 23a (24 mg, 16%) and then
b-thioglycoside 23b (98 mg, 66%). Compound 23a:
colorless oil, Rf = 0.3 (7:1, hexane/EtOAc); [a]D +8.1
1
ꢀ18.8 (c 0.8, CHCl3); H NMR (500 MHz, CDCl3): d
2.29–2.35 (m, 1H, H0-1a), 2.48–2.53 (m, 1H, H0-1b),
3.33 (t, 1H, J = 6.8 Hz, H-3), 3.46 (dd, 1H, J = 8.6,
5.9 Hz, H-5), 3.62 (dd, 1H, J = 9.3, 2.1 Hz, H-2), 3.68
(dd, 1H, J = 10.7, 5.9 Hz, H-6a), 3.75–3.80 (m, 2H, H-
1, H-6b), 3.90 (t, 1H, J = 9.5 Hz, H-4), 4.53 (d, 1H,
J = 10.7 Hz, PhCHH), 4.58 and 4.61 (ABq, 2H,
J = 12.2 Hz, PhCH2), 4.69 (d, 1H, J = 11.6 Hz,
PhCHH), 4.72 and 4.79 (ABq, 2H, J = 11.7 Hz,
PhCH2), 4.87 (d, 1H, J = 10.6 Hz, PhCHH), 5.00–5.05
(m, 3H, H0-3a, H0-3b, PhCHH), 5.63–5.71 (m, 1H, H0-
2), 7.15–7.38 (m, 20H, Ar-H); 13C NMR (125 MHz,
CDCl3): d 35.7 (C0-1), 69.7, 72.5, 73.5, 74.4, 74.5,
75.38, 75.44, 78.3, 79.8, 85.5, 117.5 (C0-3), [127.6 (3C),
127.8 (2C), 128.1 (2C), 128.2 (4C), 128.4 (7C), 128.6
(2C)(Ar-C)], 134.7 (C0-2), [138.3, 138.4 (2C), 138.8
(Ar-C ipso)]. Anal. Calcd for C37H40O5: C, 78.69; H,
7.14. Found: C, 78.67; H, 7.12.
1
(c 1.5, CHCl3); H NMR (400 MHz, CDCl3): d 3.75
(d, 1H, J = 11.2, 1.8 Hz, H-6a), 3.82–3.88 (m, 2H, H-
3, H-6b), 3.99–4.00 (m, 1H, H-2), 4.07 (t, 1H,
J = 9.4 Hz, H-4), 4.26–4.31 (m, 1H, H-5), 4.48 (d, 1H,
J = 12.0 Hz, PhCHH), 4.54 (d, 1H, J = 10.8 Hz,
PhCHH), 4.60–4.66 (m, 4H, 2PhCH2), 4.73 (d, 1H,
J = 12.4 Hz, PhCHH), 4.90 (d, 1 H, J = 10.8 Hz,
PhCHH), 5.61 (d, 1H, J = 1.6 Hz, H-1), 7.19–7.45 (m,
25H, Ar-H); 13C NMR (100 MHz, CDCl3): d 69.3,
72.0, 72.2, 72.9, 73.4, 75.1, 75.3, 76.4, 80.3, 85.9 (C-1),
[127.5, 127.6, 127.75, 127.82 (2C), 127.86 (2C), 127.95
(2C), 128.0 (2C), 128.1 (2C), 128.4 (2C), 128.47 (2C),
128.5 (2C), 128.54 (2C), 129.1 (2C), 131.8 (2C)(Ar-C)],
134.5 (Ar-S ipso), [138.1, 138.3, 138.5, 138.6 (Ar-C
ipso)]. Anal. Calcd for C40H40O5S: C, 75.92; H, 6.37.
Found: C, 75.98; H, 6.34. Compound 23b: colorless
oil, Rf = 0.28 (7:1, hexane/EtOAc); [a]D ꢀ4.1 (c 5.0,
1.9. Self-condensed ester of CB mannopyranoside (21)
1
Colorless oil, Rf = 0.30 (4:1, hexane/EtOAc); [a]D +4.8
CHCl3); H NMR (400 MHz, CDCl3): d 3.53–3.55 (m,
1
(c 1.1, CHCl3); H NMR (400 MHz, CDCl3): d 3.70–
1H, H-5), 3.61 (dd, 1H, J = 9.2, 2.8 Hz, H-3), 3.74
(dd, 1H, J = 10.8, 6.4 Hz, H-6a), 3.83 (dd, 1H,
J = 10.8, 1.6 Hz, H-6b), 3.94 (t, 1H, J = 9.6 Hz, H-4),
4.13 (d, 1H, J = 2.4 Hz, H-2), 4.53–4.61 (m, 3H,
3PhCHH), 4.67 and 4.71 (ABq, 2H, J = 11.8 Hz,
PhCH2), 4.76 (br s, 1H, H-1), 4.85 (d, 1H, J =
11.2 Hz, PhCHH), 4.88 (d, 1 H, J = 10.8 Hz, PhCHH),
5.04 (d, 1H, J = 11.6 Hz, PhCHH), 7.17–7.52 (m, 25H,
Ar-H); 13C NMR (100 MHz, CDCl3): d 69.9, 72.7,
3.83 (m, 6H), 3.87–3.88 (m, 1H), 3.90–3.97 (m, 2H),
4.00 (dd, 1H, J = 9.6, 3.2 Hz, H-6a), 4.05–4.12 (m,
1H), 4.18 (t, 1H, J = 9.8 Hz, H-4), 4.50–5.09 (m, 18H,
9PhCH2), 5.05 (br s, 1H, H-1), 6.43 (d, 1H,
J = 1.6 Hz, H0-1), 7.18–7.49 (m, 43H, Ar-H), 7.75 (d,
1H, J = 8.0 Hz, Ar-H); 13C NMR (100 MHz, CDCl3):
d 67.4, 69.0, 69.3, 72.2, 72.3, 72.5, 72.65, 72.7, 73.6,
73.7, 74.0, 74.4, 74.8, 75.0, 75.1, 75.4, 75.6, 79.2,

Y. J. Lee et al. / Carbohydrate Research 341 (2006) 1708–1716
1715
73.5, 75.0, 75.2, 75.3, 77.6, 80.2, 84.4, 87.7 (C-1), [127.0,
127.5, 127.7 (2C), 127.8 (2C), 127.83 (2C), 127.9 (2C),
128.1 (2C), 128.26 (2C), 128.3 (3C), 128.4 (2C), 128.6
(2C), 129.0 (2C), 130.6 (2C)(Ar-C)], 135.8 (Ar-S ipso),
[138.1, 138.3, 138.4, 138.6 (Ar-C ipso)]. Anal. Calcd
for C40H40O5S: C, 75.92; H, 6.37. Found: C, 76.11; H,
5.99.
(2C), 128.1 (2C), 128.2 (2C), 128.43 (2C), 128.44 (2C),
128.5 (2C), 128.51 (2C)(Ar-C)], [138.0, 138.06, 138.1,
138.3 (Ar-C ipso)]. Anal. Calcd for C34H35FO5: C,
75.26; H, 6.50. Found: C, 75.25; H, 6.57.
1.12. Phenyl 4,6-O-benzylidene-2,3-di-O-benzyl-1-thio-b-
D-mannopyranoside (25)
1.11. 2,3,4,6-Tetra-O-benzyl-D-mannopyranosyl fluoride
(24)
CB glycoside 22 (670 mg, 1.15 mmol) was subjected to
the same reaction conditions as that for the preparation
of 23 from 4. The reaction mixture was purified by flash
column chromatography (7:1, hexane/EtOAc) to give
the title compound 25 (529 mg, 85%, b only) as a color-
less oil. Rf = 0.38 (9:1:1, hexane/EtOAc/CH2Cl2); [a]D
A solution of 4 (128 mg, 0.19 mmol) and DTBMP
(94 mg, 0.46 mmol) in CH2Cl2 (12 mL) in the presence
˚
of 4 A molecular sieves was stirred for 20 min at rt
and cooled to ꢀ78 °C, then Tf2O (38 lL, 0.23 mmol)
was added. After the resulting solution was stirred at
ꢀ78 °C for 10 min, DAST (50 lL, 0.38 mmol) was
added and stirred at ꢀ78 °C for 1 h and allowed to
warm over 1 h to 0 °C. The reaction mixture was
quenched with satd aq NaHCO3, and then extracted
with CH2Cl2. The combined organic layer was washed
with satd aq NaHCO3 and brine, dried over MgSO4,
and concentrated in vacuo. The residue was purified
by flash column chromatography (4:1, hexane/EtOAc)
to afford a-glycosyl fluoride 24a (32 mg, 31%) and then
b-glycosyl fluoride 24b (62 mg, 60%). Compound 24a:
pale yellow oil, Rf = 0.53 (4:1, hexane/EtOAc); [a]D
1
ꢀ0.78 (c 1.1, CHCl3); H NMR (400 MHz, CDCl3): d
3.37–3.43 (m, 1H, H-5), 3.74 (dd, 1H, J = 9.6, 3.2 Hz,
H-3), 3.95 (t, 1H, J = 10.2 Hz, H-4), 4.18 (d, 1H,
J = 2.0 Hz, H-2), 4.29–4.34 (m, 2H, H-6a, H-6b), 4.74
and 4.89 (ABq, 2H, J = 12.4 Hz, PhCH2), 4.85 (d, 1H,
J = 0.8 Hz, H-1), 4.86 and 5.11 (ABq, 2H, J =
11.2 Hz, PhCH2), 5.64 (s, 1H, PhCHO2), 7.25–7.51 (m,
20H, Ar-H); 13C NMR (100 MHz, CDCl3): d 68.6,
71.8, 73.3, 76.0, 78.8, 79.1, 79.9, 89.2 (C-1), 101.6
(PhCHO2), [126.2 (2C), 127.6, 127.8 (2C), 127.87,
127.9, 128.3 (4C), 128.6 (2C), 128.8 (2C), 129.0,129.1
(2C), 129.3, 131.2 (2C)(Ar-C)], 135.1 (Ar-S ipso),
[137.6, 138.1, 138.4 (Ar-C ipso)]. Anal. Calcd
for C33H32O5S: C, 73.31; H, 5.97. Found: C, 73.36; H,
5.96.
1
+2.9 (c 1.4, CHCl3); H NMR (400 MHz, CDCl3): d
3.71 (dd, 1H, J = 11.2, 1.8 Hz, H-6a), 3.77 (dd, 1H,
J = 11.2, 4.4 Hz, H-6b), 3.86–3.93 (m, 3H, H-2, H-3,
H-5), 4.07 (t, 1H, J = 9.4 Hz, H-4), 4.53 (d, 2H,
J = 11.2 Hz, PhCH2), 4.61–4.70 (m, 4H, 2PhCH2),
4.80 (d, 1H, J = 12 Hz, PhCHH), 4.87 (d, 1H,
J = 10.8 Hz, PhCHH), 5.59 (dd, 1H, J1,F = 50.6,
J1,2 = 1.6 Hz, H-1), 7.15–7.36 (m, 20H, Ar-H); 13C
NMR (100 MHz, CDCl3): d 68.8 (C-6), 72.7 (PhCH2),
73.4 (PhCH2), 73.56 (PhCH2), 73.6 (d, J 34 Hz, C-2),
74.2 (C-3/4/5), 74.3 (C-3/4/5), 75.2 (PhCH2), 79.3 (C-
3/4/5), 106.5 (d, J 221 Hz, C-1), [127.6, 127.7 (3C),
127.8 (3C), 127.9, 128.0 (2C), 128.1 (2C), 128.46 (2C),
128.5 (2C), 128.6 (4C)(Ar-C)], [138.0, 138.27, 138.3,
138.34 (Ar-C ipso)]. Anal. Calcd for C34H35FO5: C,
75.26; H, 6.50. Found: C, 75.31; H, 6.46. Compound
24b: pale yellow oil, Rf = 0.38 (4:1, hexane/EtOAc);
1.13. 4,6-O-Benzylidene-2,3-di-O-benzyl-b-D-manno-
pyranosyl fluoride (26)
CB glycoside 22 (57 mg, 0.098 mmol) was subjected to
the same reaction conditions as that for the preparation
of 24 from 4. The reaction mixture was purified by flash
column chromatography (4:1, hexane/EtOAc) to give
the title compound 26 (40 mg, 91%, b only) as a pale yel-
low oil. Rf = 0.55 (3:1, hexane/EtOAc); [a]D ꢀ3.0 (c 1.1,
1
CHCl3); H NMR (400 MHz, CDCl3): d 3.37–3.43 (m,
1H, H-5), 3.65 (dd, 1H, J = 9.6, 2.8 Hz, H-3), 3.94 (t,
1H, J = 10.4 Hz, H-4), 4.00–4.01 (m, 1H, H-2), 4.24 (t,
1H, J = 9.6 Hz, H-6a), 4.35 (dd, 1H, J = 10.4, 4.8 Hz,
H6b), 4.64 and 4.76 (ABq, 2H, J = 12.4 Hz, PhCH2),
4.83 and 4.89 (ABq, 2H, J = 12.0 Hz, PhCH2), 5.28
(dd, 1H, J1,F = 49.2 Hz, J1,2 = 0.8 Hz, H-1), 5.62 (s,
1H, PhCHO2), 7.29–7.50 (m, 15H, Ar-H); 13C NMR
(100 MHz, CDCl3): d 67.0 (C-3/4/5), 68.5 (C-6), 72.9
(PhCH2), 74.9 (C-3/4/5), 75.1 (d, J 16 Hz, C-2), 76.8
(C-3/4/5), 78.3 (PhCH2), 101.7 (PhCHO2), 107.7 (d, J
216 Hz, C-1), [126.2 (2C), 127.8 (2C), 127.9,
128.0, 128.4 (2C), 128.45 (2C), 128.5 (4C), 129.1
(Ar-C)], [137.4, 137.9, 138.1 (Ar-C ipso)]. Anal. Calcd
for C27H27FO5: C, 71.98; H, 6.04. Found: C, 71.91; H,
6.09.
1
[a]D ꢀ2.2 (c 2.0, CHCl3); H NMR (400 MHz, CDCl3):
d 3.61 (dd, 1H, J = 7.6, 3.2 Hz, H-3), 3.68–3.72 (m, 1H,
H-5), 3.78 (dd, 1H, J = 10.4, 5.6 Hz, H-6a), 3.84 (dd,
1H, J = 10.4, 3.6 Hz, H-6b), 3.92–3.95 (m, 2H, H-2,
H-4), 4.49–4.60 (m, 5H, 5PhCHH), 4.72 and 4.82
(ABq, 2H, J = 12.4 Hz, PhCH2), 4.73 (d, 1H,
J = 11.2 Hz, PhCHH), 5.33 (d, 1H, J1,F = 50.8 Hz, H-
1), 7.16–7.35 (m, 20H, Ar-H); 13C NMR (100 MHz,
CDCl3): d 69.5 (C-6), 72.1 (PhCH2), 73.0 (d, J 19 Hz,
C-2), 73.4 (C-5), 73.56 (PhCH2), 73.9 (PhCH2), 74.3
(PhCH2), 75.3 (C-4), 78.6 (C-3), 107.1 (d, J = 218 Hz,
C-1), [127.7, 127.8, 127.83, 127.85, 127.9 (2C), 128.0

1716
Y. J. Lee et al. / Carbohydrate Research 341 (2006) 1708–1716
Levy, D. E., Fugedi, P., Eds.; CRC Press: Boca Raton,
¨
Acknowledgements
2006; pp 269–348.
9. (a) Nicolaou, K. C.; Dolle, R. E.; Chucholowski, A.;
Randall, J. L. J. Chem. Soc., Chem. Commun. 1984, 1153–
1154; (b) Matsumoto, T.; Katsuki, M.; Suzuki, K.
Tetrahedron Lett. 1989, 30, 833–836.
This work was supported by a grant from the Korea
Science and Engineering Foundation through the Center
for Bioactive Molecular Hybrids (CBMH).
10. (a) Schmidt, R. R.; Hoffmann, M. Tetrahedron Lett. 1982,
23, 409–412; (b) Schmidt, R. R.; Hoffmann, M. Angew.
Chem., Int. Ed. Engl. 1983, 22, 406–407; (c) Schmidt, R.
R.; Effenberger, G. Liebigs Ann. Chem. 1987, 825–
831.
11. (a) Dawe, R. D.; Fraser-Reid, B. J. Chem. Soc., Chem.
Commun. 1981, 1180–1181; (b) Danishefsky, S. J.; Kerwin,
J. F., Jr. J. Org. Chem. 1982, 47, 3803–3805; (c) Gry-
nkiewicz, G.; BeMiller, J. N. Carbohydr. Res. 1982, 108,
229–235.
12. (a) Lewis, M. D.; Cha, J. K.; Kishi, Y. J. Am. Chem. Soc.
1982, 104, 4976–4978; (b) Kraus, G. A.; Molina, M. T.
J. Org. Chem. 1988, 53, 752–753.
13. (a) Williams, R. M.; Stewart, A. O. Tetrahedron Lett.
1983, 24, 2715–2718; (b) Williams, R. M.; Stewart, A. O.
J. Am. Chem. Soc. 1985, 107, 4289–4296; (c) Kozikowski,
A. P.; Konoike, T.; Ritter, A. Carbohydr. Res. 1987, 171,
109–124.
14. (a) Plante, O. J.; Palmacci, E. R.; Andrade, R. B.;
Seeberger, P. H. J. Am. Chem. Soc. 2001, 123, 9545–
9554; (b) Palmacci, E. R.; Seeberger, P. H. Org. Lett. 2001,
3, 1547–1550.
15. Kim, K. S.; Kim, J. H.; Lee, Y. J.; Lee, Y. J.; Park, J.
J. Am. Chem. Soc. 2001, 123, 8477–8481.
16. Kim, K. S.; Park, J.; Lee, Y. J.; Seo, Y. S. Angew. Chem.,
Int. Ed. 2003, 42, 459–462.
17. Lee, Y. J.; Lee, K.; Jung, E. H.; Jeon, H. B.; Kim, K. S.
Org. Lett. 2005, 7, 3263–3266.
References
1. Sezaki, M.; Kondo, S.; Maeda, K.; Umezawa, H.; Ohno,
M. Tetrahedron 1970, 26, 5171–5190.
2. Nadig, H.; Sequin, U. Helv. Chim. Acta 1987, 70, 1217–
1228.
3. (a) Strelitz, F.; Flon, H.; Asheshov, I. N. J. Bacteriol.
1955, 69, 280–283; (b) Weiss, U.; Yoshihira, K.; Highet, R.
J.; White, R. J.; Wei, T. T. J. Antibiot. 1982, 35, 1194–
1201.
4. (a) Findlay, J. A.; Liu, J.-S.; Radics, L.; Rakhit, S. Can. J.
Chem. 1981, 59, 3018–3020; (b) Sehgal, S. N.; Czerkawski,
H.; Kudelski, A.; Pandev, K.; Saucier, R.; Vezina, C. J.
Antibiot. 1983, 36, 355–361.
5. (a) Omura, S.; Tanaka, H.; Oiwa, R.; Awaya, J.; Masuma,
R.; Tanaka, K. J. Antibiot. 1977, 30, 908–916; (b)
Imamura, N.; Kakinuma, K.; Ikekawa, N.; Tanaka, H.;
Omura, S. J. Antibiot. 1981, 34, 1517–1518.
6. (a) Hanessian, S.; Pernet, A. G. Adv. Carbohydr. Chem.
Biochem. 1976, 33, 111–188; (b) Daves, G. D.; Cheng, C.
C. Prog. Med. Chem. 1976, 13, 303–349; (c) Suhadolnik,
R. J. Nucleoside Antibiotics; Wiley-Interscience: New
York, 1970.
7. Weatherman, R. V.; Mortell, K. H.; Chervenak, M.;
Kiessling, L. L.; Toone, E. J. Biochemistry 1996, 35, 3619–
3624.
18. (a) Kwon, Y. T.; Lee, Y. J.; Lee, K.; Kim, K. S. Org. Lett.
2004, 6, 3901–3904; (b) Kim, K. S.; Kang, S. S.; Seo, Y. S.;
Kim, H. J.; Lee, Y. J.; Jeong, K.-S. Synlett 2003, 1311–
1314.
19. Rao, V. S. R.; Qasba, P. K.; Balaji, P. V.; Chandra-
sekaran, R. Conformation of Carbohydrates; Harwood
Academic: Amsterdam, 1998.
8. (a) Postema, M. H. D. C-Glycoside Synthesis; CRC
Press: London, UK, 1995; (b) Levy, D. E.; Tang, C.
The Chemistry of C-Glycosides; Pergamon: Oxford, UK,
1995; (c) Du, Y.; Linhardt, R. J.; Vlahov, I. R.
Tetrahedron 1998, 54, 9913–9959; (d) Postema, M.
H. D.; Calimente, D. In Glycochemistry: Principles,
Synthesis, and Applications; Wang, P. G., Bertozzi, C.
R., Eds.; Marcel Dekker: New York, 2001; pp 77–131;
(e) Levy, D. E. In The Organic Chemistry of Sugars;
20. Crich, D.; Sun, S. J. Am. Chem. Soc. 1997, 119, 11217–
11223.