Sialylation reactions with 5-N,7-O-carbonyl-protected sialyl donors: unusual stereoselectivity with nitrile solvent assistance

Article abstract of DOI:10.1016/j.carres.2008.05.005

A 5-N,7-O-carbonyl-protected sialyl donor was synthesized, and, unexpectedly, this donor showed β-selectivity (α/β = 1/2.4-1/20) on coupling with sugar acceptors in acetonitrile upon treatment with various promoter systems. For the coupling reaction in dichloromethane, a modified Ellervik's method (IBr and AgClO₄·H₂O) was highly effective in activating the 5-N,7-O-carbonyl donor, providing moderate α-selectivity (α/β = ～1.8/1).

Full text of DOI:10.1016/j.carres.2008.05.005

Available online at www.sciencedirect.com
Carbohydrate Research 343 (2008) 1585–1593
Sialylation reactions with 5-N,7-O-carbonyl-protected sialyl donors:
unusual stereoselectivity with nitrile solvent assistance
Hidenori Tanaka,a Hiromune Ando,b,* Hideharu Ishiharaa and Mamoru Koketsub,*
aDepartment of Chemistry, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
bDivision of Instrumental Analysis, Life Science Research Center, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
Received 8 February 2008; received in revised form 19 April 2008; accepted 4 May 2008
Available online 8 May 2008
Abstract—A 5-N,7-O-carbonyl-protected sialyl donor was synthesized, and, unexpectedly, this donor showed b-selectivity (a/b =
1/2.4–1/20) on coupling with sugar acceptors in acetonitrile upon treatment with various promoter systems. For the coupling
reaction in dichloromethane, a modified Ellervik’s method (IBr and AgClO4ÁH2O) was highly effective in activating the 5-N,7-O-
carbonyl donor, providing moderate a-selectivity (a/b = ꢀ1.8/1).
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Sialylation; N,O-Carbonyl-protected sialyl donor; Nitrile solvent effect; Stereoselectivity
1. Introduction
method utilizes nitrile solvents as a stereodirecting
method to generate a-sialosides predominantly,2 while
the latter utilizes sialyl glycosyl donors equipped with
a-directing functionality at C-33 or C-1.4
Sialic acids are one of the biologically important sugar
residues of oligosaccharides and typically occupy the
distal end of glycan chains through an a-glycosic linkage
to other sugar residues such as galactose, glucose, and
galactosamine. The arrangement of sialic acids at the
outermost positions of glycoconjugates enables their
participation in carbohydrate–protein interactions
that mediate various essential biological processes such
as cell differentiation, cell adhesion, cellular immune
response, fertilization, oncogenesis, and viral infection.
It is well known that the difficulty in synthesizing a-
sialosides has been a central issue in carbohydrate chem-
istry. This difficulty is attributable to the inherent struc-
tural disadvantages of sialic acid, namely the presence of
the C-2 ketal carbon adjacent to the carboxyl group and
the C-3 methylene carbon. The various methods devel-
oped to overcome these disadvantages can be classified
into nitrile solvent assistance-dependent and nitrile
solvent assistance-independent sialylations.1 The former
Since reporting that an N-Troc-protected sialyl donor
exhibits high reactivity during glycosylation with the
assistance of a nitrile solvent,5 we have focused our
attention on the effect of the C-5 modification of the sial-
yl donor on a-selective sialylation. Similarly, several
reports have been published on C-5-modified sialyl do-
nors such as N-trifluoroacetyl,6 N,N-diacetyl,7 5-azido,8
N-phthaloyl,9 and 4-O,5-N-oxazolidinone sialyl do-
nors.10 Very recently, Crich’s group was the first to
report the synthesis of the 5-N,7-O-oxazinanone sialyl
donor and its application in glycosylation reactions.
Their report demonstrated that the 5-N,7-O-oxazina-
none group served as a powerful disarming and b-direct-
ing element for the coupling reaction of the sialyl
donor.11 As part of our continuous investigation on
the fine tuning of the reactivity of sialyl donors, we have
also turned our attention to the effect of cyclic carbonate
within the sialyl donor on the glycosylation reaction.
Herein, we report the results of the glycosylations
using a homolog of Crich’s 5-N,7-O-oxazinanone sialyl
donor.
*
Corresponding authors. Tel./fax: +81 58 293 3189; e-mail: hando@
gifu-u.ac.jp
0008-6215/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2008.05.005

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H. Tanaka et al. / Carbohydrate Research 343 (2008) 1585–1593
2. Results and discussion
paring the 1H nuclear magnetic resonance (NMR) spec-
tra of 3 and 4. The spectra showed that the signal for
C-7 in 3 was at 3.22 ppm while that in 4 was shifted
downfield to 4.60 ppm. Interestingly, the ring-closing
reaction exclusively afforded a six-membered ring; how-
ever, the reason underlying this process remains unclear.
After the acid hydrolysis of acetonide moiety, the result-
ing hydroxyls were protected with acetyl groups using
the conventional method to give 6 in 71% yield over
the two steps
2.1. Synthesis of sialyl donor
We have designed a phenylthioglycoside of 4,8,9-tri-
O-acetyl-5-N,7-O-oxazinanone sialic acid (6) as a novel
glycosyl donor to compare its donor properties with
those of the corresponding 4-O,5-N-oxazolidinone
derivatives reported by the De Meo10b and Crich
groups.10c For the synthesis of 6, we exploited the
N-Boc-protected sialoside 2 as a precursor of the oxaz-
inanone, following a reported method for synthesizing
cyclic carbamates.12 The synthesis of 6 started from
the reported phenylthioglycoside of N-acetyl sialic acid
derivative 113 (Scheme 1). Thus, the Boc group was
introduced at the C-5 nitrogen by the treatment of 1
with Boc2O and 4-dimethylaminopyridine in pyridine,
and all acetyl groups were removed by Zemplen’s meth-
od to afford N-Boc-protected sialoside 2 in 75% yield
over the two steps. Unfortunately, the treatment of 2
with sodium hydride failed to selectively furnish the
5-N,7-O-oxazinanone structure, producing several by-
products together with unreacted 2. Therefore, 2 was
treated with 2,2-dimethoxypropane and ( )-10-cam-
phorsulfonic acid in acetonitrile to protect C-8 and
C-9 hydroxyl groups as an isopropylidene acetal. The
product, 3, was again treated with 10 equiv of sodium
hydride in tetrahydrofuran at 0?40 °C to produce the
5-N,7-O-oxazinanone derivative 4 in 88% yield. We have
characterized 5,7-oxazinanone moiety within 4 by com-
2.2. Glycosylation reactions
To evaluate the properties of the sialyl donor, 6
(1.0 equiv) was reacted with the known glucosyl acceptor
7 (1.0 equiv) in the presence of various glycosylation pro-
moters for the thiosialoside donors (Table 1). Initially,
glycosylation by the NIS (1.5 equiv)–TfOH (0.3 equiv)
promoter system14 at À40 °C in MeCN was explored.
However, the reaction showed b-selectivity, producing
a 1:3.3 mixture of the a/b-isomers of 8 in 89% yield (entry
1). On the other hand, the use of CH2Cl2 and toluene
slightly improved the a-selectivity, giving an anomeric
mixture in 70% (a:b = 1.1:1) and 18% (a:b = 1.6:1)
yields, respectively (entries 2 and 3). The anomeric con-
figuration of a sialyl linkage in 8 was assigned by
NMR spectroscopy (1H, 13C), and heteronuclear multi-
ple bond coherence (HMBC) by comparison with the lit-
erature.15 In addition, the H-3eq of a- and b-isomers
resonated at 2.75 and 2.57 ppm, respectively (a > b); for
1. Boc2O
OAc
COOMe
AcO
OH
COOMe
O
SPh
DMAP
Pyr
HO
BocHN
OH
O
SPh
AcHN
OAc
2. NaOMe
MeOH
rt
75% (2 steps)
OAc
OH
1
2
NaH
THF
DMP
CSA
O
COOMe
SPh
O
0 °C to 40 °C
O
MeCN
rt
BocHN
OH
88%
OH
3
96%
Ac2O
Pyr
rt
COOMe
SPh
O
COOMe
SPh
O
O
O
O
N
N
O
H
OAc
OAc
H
OH
OR
94%
OAc
OR
6
4 R = Isp
5 R = H
80% aq. AcOH
rt to 40 °C
76%
DMP = 2,2-Dimethoxypropane
CSA = ( )-10-Camphorsulfonic acid
Isp = Isopropylidene
Scheme 1. Synthesis of 5-N,7-O-carbonyl sialyl donor 6.

H. Tanaka et al. / Carbohydrate Research 343 (2008) 1585–1593
1587
H-4, the signals were assigned as 4.64 and 5.05 ppm,
respectively (a < b). Furthermore, the J7,8 coupling con-
stant of a-isomer (7.3 Hz) was greater than that of the b-
isomer (3.4 Hz), which is in agreement with the reported
empirical rules.16 Although we have examined glycosyla-
tions in other solvents such as dimethylformamide and
THF, a glycosylated product was not produced (entries
4 and 5). Furthermore, the use of TMSOTf (0.3 equiv)
or Cu(OTf)2 (1.1 equiv) as an acid partner showed no
distinct enhancement of a-selectivity (18%, a:b = 1.4:1;
41%, a:b = 1.2:1, entries 6 and 7).
product 15 was obtained as a 1:1 mixture (entry 2). In the
case of the coupling with secondary hydroxyl groups, the
stereoselectivity varied depending on the structure of the
acceptors. Thus, 6 was glycosylated with 2-adamantanol
with the optimum a-selectivity to produce a 1.8:1 mix-
ture of a:b sialoside 16 in 38% yield (entry 3). A similar
result was obtained in the case of sialylation with the
galactosyl acceptor 12 containing a free 3,4-diol; a mix-
ture of a:b-isomers of the (2?3)-linked disaccharide 17
in a ratio of 1.8:1 was produced in 35% yield (entry 4).
Conversely, the 2,4,6-tribenzylated analog 13 was sial-
ylated nonstereoselectively (entry 5).
Similar results were obtained when glycosylation was
promoted by PhSeOTf.17 In MeCN–CH2Cl2, the
PhSeOTf-promoted glycosylation produced the b-sialo-
side preferentially (38%, a:b = 1:2.4, entry 8). Con-
versely, in CH2Cl2, the production of the a-sialoside
was slightly predominant (46%, a:b = 1.4:1, entry 9).
On the other hand, van Boom’s activation18 (Ph2SO,
TTBP, Tf2O) provided b-selective glycosylations when
carried out both in MeCN and in CH2Cl2 (entries 10
and 11). In all the above-mentioned glycosylations, the
mole quantity of the recovered sialyl donor 6 was almost
consistent with that of the recovered acceptor 7. The b-
selectivity of glycosidation of 6 in MeCN is in agreement
with the previous results of the 5-N,7-O-oxazinanone
sialyl donor reported by Crich and coworkers.11 In the
above-mentioned cases of entries 3–11, the low yields
of glycosylated products were attributed to the incom-
plete activation of 6.
2.3. Conclusions
We have synthesized the 5-N,7-O-carbonyl sialyl donor
6 and described a regioselective ring-closing reaction.
The fused 5-N,7-O-oxazolidinone ring within this sialyl
donor exerted a negative effect on nitrile solvent-assisted
a-selective sialylation. In non-participative solvents such
as CH2Cl2, the modified Ellervik’s system (IBr and Ag-
ClO4ÁH2O) was proven to be highly effective in promot-
ing the glycosidation of 6. However, good a-selectivity
could not be achieved.
3. Experimental
3.1. General procedures
Finally, as a result of broad screening of promoter sys-
tems for sialylation, a modified Ellervik’s system19
(2.0 equiv of IBr and 3.0 equiv of AgClO4ÁH2O) was pro-
ven to be highly effective in promoting the glycosidation
of 6. The modified system could complete the glycosyla-
tion of 7 with 6 in CH2Cl2 at À94 °C within 30 min to give
a mixture of a:b-isomers of 8 (a:b = 1.2:1) in 70% yield. In
contrast, the reaction using the original promotor system
(IBr and AgOTf) took 95 h to complete at temperatures
between À40 °C and room temperature, producing a 1:1
a:b-mixture in 56% yield (entries 12 and 13). In EtCN,
b-sialoside production was again predominant and affor-
ded a 1:20 mixture in 21% yield (entry 14). With the mod-
ified promoter system, temperature had a small effect on
a-selectivity; at À60 °C, the reaction produced a 1.3:1
mixture of 8 in 58% yield (entry 15). In addition, the cor-
responding 2,3-en derivative of 6 was obtained as the ma-
jor by-product, which was not obtained in entries 1–11.
On the basis of these results, we chose the modified
Ellervik’s system for subsequent coupling reactions with
a series of acceptors (Table 2). The anomeric configura-
tions of glycosides were determined using the HMBC
technique. The sialylation of the C-6 primary hydroxyl
of 1,2:3,4-diacetone-galactose 9 afforded the correspond-
ing disaccharide 14 in 83% yield as a 1:1 mixture of ster-
eoisomers (entry 1). Analogously, along with the 4,6-
dihydroxy galactoside derivative 10, the (2?6)-sialylated
1H and 13C NMR spectra were taken by Varian Unity
INOVA 400, 500, Jeol ECX 400P, and ECA 500, 600.
Chemical shifts are expressed in ppm (d) relative to the
signal of either CHCl3 or Me4Si, adjusted to 7.26 or
0.00 ppm, respectively. MALDI-TOF MS spectra were
recorded in positive ion mode on a Brucker Autoflex
with the use of a-cyano-4-hydroxy-cinnamic acid
(CHCA) as a matrix. Molecular sieves were purchased
from Wako Chemicals Inc. and dried at 300 °C for 2 h
in muffle furnace prior to use. Reaction solvents were
dried over molecular sieves and used without purifica-
tion. TLC analysis was performed on Merck TLC (Silica
Gel 60F254 on glass plate). Silica Gel 60N (spherical,
neutral) manufactured by Kanto Chemical Co. Inc.
was used for flash column chromatography. The quan-
tity of silica gel was usually estimated as 100- to 150-fold
weight of sample to be charged. Solvent systems in
chromatography are specified in v/v. Evaporation and
condensation were carried out in vacuo.
3.2. Methyl (phenyl 5-tert-butoxycarbonylamino-3,5-
dideoxy-2-thio-D-glycero-a-D-galacto-2-nonulopyran-
osid)onate (2)
A mixture of methyl (phenyl 5-acetamido-3,5-dideoxy-2-
thio-D-glycero-a-D-galacto-2-nonulopyranosid)onate
1

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H. Tanaka et al. / Carbohydrate Research 343 (2008) 1585–1593
Table 1. Glycosidations of sialyl donor 6 with glucosyl acceptor 7 under various conditions
COOMe
COOMe
OH
Promoter
O
O
O
O
SPh
O
O
BnO
BnO
BnO
BnO
O
+
O
O
N
N
MS 3Å
H
H
OAc
OAc
OAc
OAc
BnO
Solvent
OMe
BnO
OMe
OAc
OAc
6
7
8
(1.0 eq)
(1.0 eq)
Entry
1
Promoter
Solvent
CH3CN
Temp (°C)
À40
Time
Yield (%)
89
a:ba
NIS (1.5 equiv)
TfOH (0.3 equiv)
NIS (1.5 equiv)
TfOH (0.3 equiv)
NIS (1.5 equiv)
TfOH (0.3 equiv)
NIS (1.5 equiv)
TfOH (0.3 equiv)
NIS (1.5 equiv)
TfOH (0.3 equiv)
NIS (1.5 equiv)
4 h
1:3.3
2
3
CH2Cl2
Toluene
DMF
À40
4 h
70
18
0
1.1:1
1.6:1
—
À40
98 h
24 h
24 h
36 h
36 h
24 h
24 h
24 h
4
À40 to rt
À40 to rt
À40 to rt
À40 to rt
À80 to rt
À80 to rt
À80 to rt
5
THF
0
—
6
CH2Cl2
CH2Cl2
18
41
38
46
38
1.4:1
1.2:1
1:2.4
1.4:1
1:4.5
TMSOTf (0.3 equiv)
NIS (1.5 equiv)
7
Cu(OTf)2 (1.1 equiv)
PhSeBr (3.0 equiv)
AgOTf (3.0 equiv)
PhSeBr (3.0 equiv)
AgOTf (3.0 equiv)
Ph2SO (3.0 equiv)
Tf2O (1.1 equiv)
8
CH3CN–CH2Cl2 (1:2)
CH2Cl2
9
10
CH2Cl2
TTBP (2.0 equiv)
Ph2SO (3.0 equiv)
Tf2O (1.1 equiv)
TTBP (2.0 equiv)
IBr (2.0 equiv)
11
CH3CN–CH2Cl2 (1:3)
À80 to rt
24 h
95 h
35
1:3.4
12
13
14
15
CH2Cl2
CH2Cl2
EtCN
À40 to rt
À94
56
70
21
58
1.1:1
1.2:1
1:20
AgOTf (3.0 equiv)
IBr (2.0 equiv)
30 min
20 h
AgClO4ÁH2O (3.0 equiv)
IBr (2.0 equiv)
À94 to rt
À60
AgClO4ÁH2O (3.0 equiv)
IBr (2.0 equiv)
CH2Cl2
30 min
1.3:1
AgClO4ÁH2O (3.0 equiv)
a Determined by 1H NMR analysis of the a:b mixture.
(27.4 g, 48.1 mmol), Boc2O (55.2 mL, 228 mmol), DMAP
(588 mg, 4.81 mmol), and NEt3 (4.9 mL, 35.2 mmol) in
THF (200 mL) was heated at reflux for 17.5 h under an
Ar atmosphere. The progress of the reaction was moni-
tored by TLC (CHCl3–MeOH 10:1). After cooling to rt,
the reaction mixture was concentrated, extracted with
EtOAc, washed with 2 M HCl, satd aq NaHCO3, and
brine, dried over Na2SO4, and concentrated. The residue
was purified via chromatography on a short column of sil-
ica gel (EtOAc–hexane 1:3?3:2) to give a crude syrup,
which was then exposed to high vacuum for 12 h. The
dried syrup was dissolved in MeOH (200 mL), and 25%
NaOMe in MeOH (1.04 g, 4.81 mmol) was added at rt un-
der an Ar atmosphere. After stirring for 11 h, the mixture
was acidified with Dowex (H+) and filtered. The filtrate
was concentrated and the residue obtained was dissolved
in a minimum quantity of MeOH, and precipitated with
Et2O to afford 2 as an amorphous mass (17.2 g, 75%):
[a]D +82.0 (c 0.3, CH3OH); 1H NMR (400 MHz,
CD3OD) d 7.56–7.34 (m, 5H, Ph), 4.86 (1H, NH), 3.80
(m, 2H), 3.63–3.47 (m, 7H), 3.34 (m, 1H), 2.84 (dd, 1H,
J3eq,4 = 4.6, Hz, Jgem = 12.9 Hz, H-3eq), 1.85 (dd, 1H, J3-
ax,4 = 11.0 Hz, H-3ax), 1.43 (s, 9H, –C(CH3)3); 13C NMR
(100 MHz, CD3OD) d 171.0, 159.5, 137.8, 131.1, 130.1,
129.8, 87.8, 80.9, 77.8, 73.0, 70.2, 68.9, 64.5, 54.3, 53.3,
41.8, 28.7; MALDI-TOFMS m/z calcd for
[C21H31NO8S+K]+: 496.14. Found: 496.14.
3.3. Methyl (phenyl 5-tert-butoxycarbonylamino-8,9-iso-
propylidene-3,5-dideoxy-2-thio-D-glycero-a-D-galacto-2-
nonulopyranosid)onate (3)
To a solution of compound 2 (4.70 g, 9.93 mmol) in
MeCN (100 mL) were added DMP (1.41 mL, 11.5

H. Tanaka et al. / Carbohydrate Research 343 (2008) 1585–1593
Table 2. Glycosidations of sialyl donor 6 with various acceptors
1589
9 ~ 13 (1.0 eq)
HO
COOMe
O
COOMe
SPh
IBr (2.0 eq)
O
O
O
O
AgClO4H 2O (3.0 eq)
O
O
O
N
N
H
H
OAc
OAc
OAc
OAc
MS3Å
CH2Cl2
-94 °C
OAc
OAc
6 (1.0 eq)
14 ~ 18
Entry
Acceptora
Time (min)
Product
Yield (%)
a:bb
O
O
OH
O
1
15
14
83
1:1
O
O
9
HO
BnO
OH
O
2
3
4
5
20
15
15
15
15
16
17
18
62
38
35c
38
1:1
BnO
OMe
10
HO
1.8:1
1.8:1c
1:1
11
HO
OBn
O
HO
BnO
OMe
12
BnO
HO
OBn
O
BnO
OMe
13
a Arrows point to the glycosylation site.
b Determined by 1H NMR analysis of the a:b mixture.
c Determined after the acetylation of the a:b mixture.
mmol) and CSA (188 mg, 810 lmol) at rt under an Ar
atmosphere. The progress of the reaction was monitored
by TLC (CHCl3–MeOH 10:1). After stirring for 10 min,
the reaction mixture was quenched by the addition of
NEt3, and concentrated. The residue was purified by
column chromatography on silica gel (CHCl3–MeOH,
90:1) to give 3 as white foam (4.90 g, 96%): [a]D À6.3
(c 0.5, CHCl3); 1H NMR (400 MHz, DMSO-d6) d
7.53–7.34 (m, 5H, Ph), 6.71 (d, 1H, J5,NH = 8.7 Hz,
NH), 5.08 (d, 1H, J = 6.0 Hz, –OH), 4.51 (d, 1H,
1.61 (dd, 1H, J3ax,4 = 11.9 Hz, H-3ax), 1.37 (s, 9H,
–C(CH3)3), 1.26, 1.17 (2s, 6H, –C(CH3)2); 13C NMR
(100 MHz, DMSO-d6) d 168.5, 156.3, 136.0, 129.6,
129.2, 128.6, 107.7, 86.7, 78.0, 76.3, 75.1, 69.3, 66.5,
52.6, 51.9, 41.0, 28.2, 26.7, 25.4; MALDI-TOFMS m/z
calcd for [C24H35NO8S+K]+: 536.17. Found: 536.20.
3.4. Methyl (phenyl 5-amino-5-N,7-O-carbonyl-8,9-iso-
propylidene-3,5-dideoxy-2-thio-D-glycero-a-D-galacto-2-
nonulopyranosid)onate (4)
J5,6 = 6.4 Hz, H-6), 4.03 (q, 1H, J7,8 = J8,9a = J8,9b
=
6.6 Hz, H-8), 3.87 (t, 1H, Jgem = 7.2 Hz, H-9a), 3.76 (t,
1H, H-9b), 3.46–3.22 (m, 6H, H-4, H-5, H-7, COOMe),
2.57 (dd, 1H, J3eq,4 = 4.3 Hz, Jgem = 12.5 Hz, H-3eq),
To a solution of compound 3 (4.90 g, 9.54 mmol) in
THF (500 mL) was added 60% NaH (3.82 g, 95.5 mmol)
portion-wise at 0 °C under an Ar atmosphere, then the

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H. Tanaka et al. / Carbohydrate Research 343 (2008) 1585–1593
reaction mixture was stirred at 40 °C for 27 h. The
progress of the reaction was monitored by TLC
(CHCl3–MeOH 10:1). After cooling to 0 °C, the reac-
tion mixture was quenched by the addition of AcOH,
and the solution was extracted with EtOAc, and washed
with H2O and brine. The organic layer was dried over
Na2SO4, concentrated, and purified by column chroma-
tography on silica gel (CHCl3–MeOH 100:1?50:1) to
give 4 as a colorless syrup (3.68 g, 88%): [a]D +43.1 (c
of MeOH, and concentrated with toluene. The residue
was extracted with EtOAc, and washed with 2 M HCl,
satd NaHCO3, and brine. The organic layer was dried
over Na2SO4, and concentrated. The resulting residue
was purified by column chromatography on silica gel
(EtOAc–Hexane 4:3) to give 6 as a colorless syrup
(96 mg, 94%): [a]D +37.5 (c 0.7, CHCl3); 1H NMR
(500 MHz, CDCl3) d 7.50–7.32 (m, 6H, NH, Ph),
5.64 (m, 1H, H-8), 4.65 (m, 2H, H-4, H-7), 4.49 (dd,
1H, J8,9a = 3.0 Hz, Jgem = 12.0 Hz, H-9a), 4.33 (dd,
1H, J8,9b = 6.0 Hz, H-9b), 3.90 (dd, 1H, J5,6 = 10.8 Hz,
J6,7 = 4.9 Hz, H-6), 3.77 (dd, 1H, J4,5 = 10.0 Hz, H-5),
3.51 (s, 3H, COOMe), 2.94 (dd, 1H, J3eq,4 = 4.6 Hz,
Jgem = 14.6 Hz, H-3eq), 2.20, 2.11 and 2.10 (3s, 9H, 3
Ac), 1.81 (dd, 1H, J3ax,4 = 11.4 Hz, H-3ax); 13C NMR
(125 MHz, CDCl3) d 170.4, 169.9, 167.3, 151.5, 135.7,
129.9, 128.8, 128.7, 88.9, 77.2, 72.8, 70.3, 70.0, 68.0,
62.9, 52.8, 50.6, 36.7, 21.2, 20.8, 20.6; MALDI-TOFMS
m/z calcd for [C23H28NO11S+H]+: 526.13. Found:
526.14.
1
0.9, CHCl3); H NMR (400 MHz, CDCl3) d 7.57–7.30
(m, 5H, Ph), 7.17 (s, 1H, NH), 4.60 (t, 1H, J6,7
=
J7,8 = 5.3 Hz, H-7), 4.48 (q, 1H, J8,9a = J8,9b = 6.2 Hz,
H-8), 4.33 (br s, 1H, –OH), 4.13–4.03 (m, 2H, H-9a,
H-9b), 3.67 (dd, 1H, J5,6 = 10.3 Hz, H-6), 3.58 (s, 3H,
COOMe), 3.54 (m, 1H, H-4), 3.25 (t, 1H, J4,5
9.8 Hz, H-5), 2.85 (dd, 1H, J3eq,4 = 4.3 Hz, Jgem
=
=
13.5 Hz, H-3eq), 1.79 (dd, 1H, J3ax,4 = 11.5 Hz,
H-3ax), 1.53 and 1.44 (2s, 6H, –C(CH3)2); 13C NMR
(100 MHz, CDCl3) d 168.6, 153.1, 136.5, 130.0, 128.7,
128.6, 110.1, 88.6, 76.1, 74.4, 69.4, 68.8, 65.7, 54.0,
52.9, 26.4, 25.6; MALDI-TOFMS m/z calcd for
[C20H25 NO8S+Na]+: 462.11. Found: 462.49.
3.7. General procedure for the glycosylation with 6 under
the promotion of IBr–AgClO4ÁH2O
3.5. Methyl (phenyl 5-amino-5-N,7-O-carbonyl-3,5-dide-
oxy-2-thio-D-glycero-a-D-galacto-2-nonulopyran-
osid)onate (5)
A
mixture of compound 6 (100 lmol), acceptor
(100 lmol), AgClO4ÁH2O (300 lmol), and activated
˚
3 A molecular sieves (500 mg) in CH2Cl2 (2.0 mL) was
A suspension of compound 4 (575 mg, 1.31 mmol) in
80% AcOH (13 mL) was stirred at 40 °C for 1.5 h. The
progress of the reaction was monitored by TLC
(CHCl3–MeOH 5:1). After cooling to rt, the reaction
mixture was co-evaporated with MeOH. The residue
was purified by column chromatography on silica gel
(CHCl3–MeOH, 20:1?10:1) to give 5 as a colorless syr-
up (400 mg, 76%): [a]D +77.7 (c 0.4, CH3OH); 1H NMR
(400 MHz, DMSO-d6) d 7.51–7.36 (m, 5H, Ph), 7.14 (s,
stirred for 1 h at rt under an Ar atmosphere in the dark,
and then cooled to À94 °C. After stirring for 30 min, a
1.0 M solution of IBr in CH2Cl2 (200 lmol) was added
dropwise, and the mixture was stirred for 15 min. The
reaction mixture was diluted with EtOAc, warmed to
ambient temperature, and quenched by the addition of
satd aq NaHCO3. After stirring vigorously for 10 min,
the mixture was filtered through a pad of Celite. The
combined filtrate and washings were washed with satd
aq Na2S2O3 and brine. The organic layer was dried over
Na2SO4 and concentrated. The residue was purified on
Sephadex LH-20 to give an anomeric mixture of glycos-
idated product, which was then separated by column
chromatography on silica gel.
1H, NH), 5.34 (m, 2H, H-7, –OH), 4.71 (t, 1H, J8,9a
=
Jgem = 4.8 Hz, H-9a), 4.32 (t, 1H, J5,6 = J6,7 = 4.1 Hz,
H-6), 3.96 (m, 1H, H-8), 3.66–3.52 (m, 2H, H-5,
H-9b), 3.50 (s, 3H, COOMe), 3.31 (m, 1H, H-4), 2.60
(dd, 1H, J3eq,4 = 4.1 Hz, Jgem = 12.8 Hz, H-3eq),
1.62 (dd, 1H, J3ax,4 = 12.2 Hz, H-3ax); 13C NMR
(100 MHz, DMSO-d6) d 168.0, 151.7, 135.9, 129.9,
128.9, 128.6, 88.0, 74.9, 73.7, 70.4, 68.3, 62.4, 54.1,
52.6; MALDI-TOFMS m/z calcd for [C17H21NO8S
+K]+: 438.06. Found: 438.77.
3.8. Methyl 2,3,4-tri-O-benzyl-6-O-(methyl 4,8,9-tri-O-
acetyl-5-amino-5-N,7-O-carbonyl-3,5-dideoxy-D-glycero-
a-D-galacto-2-nonulopyranosylonate)-a-D-glucopyran-
oside (8a)
3.6. Methyl (phenyl 4,8,9-tri-O-acetyl-5-amino-5-N,7-O-
carbonyl-3,5-dideoxy-2-thio-D-glycero-a-D-galacto-2-
nonulopyranosid)onate (6)
[a]D +29.5 (c 1.3, CHCl3); 1H NMR (500 MHz, CDCl3)
d 7.34–7.24 (m, 15H, 3 Ph), 6.12 (s, 1H, NH), 5.57 (m,
1H, H-8Neu), 4.97 (d, 1H, –CH2Ph), 4.87 (d, 1H,
–CH2Ph), 4.78 (2d, 2H, 2 –CH2Ph), 4.72 (dd, 1H,
J6,7 = 5.2 Hz, J7,8 = 7.3 Hz, H-7Neu), 4.64 (m, 2H,
H-4Neu, H-9aNeu), 4.51 (d, 1H, –CH2Ph), 4.46 (m, 2H,
To a solution of compound 5 (78 mg, 195 mmol) in pyr-
idine (1.0 mL) was added Ac2O (0.5 mL) at rt under an
Ar atmosphere. The progress of the reaction was moni-
tored by TLC (CHCl3–MeOH 10:1). After stirring for
3.5 h, the reaction mixture was quenched by the addition
H-1Glc, –CH2Ph), 4.23 (dd, 1H, J8,9b = 5.7 Hz, Jgem
12.0 Hz, H-9bNeu), 4.02 (dd, 1H, J5,6 = 10.3 Hz, J6,7
=
=
5.1 Hz, H-6Neu), 3.95 (t, 1H, J2,3 = J3,4 = 9.2 Hz,

H. Tanaka et al. / Carbohydrate Research 343 (2008) 1585–1593
1591
H-3Glc), 3.75–3.63 (m, 7H, H-5Neu, COOMe, H-5Glc, H-
6aGlc, H-6bGlc), 3.44 (dd, 1H, J1,2 = 3.5 Hz, H-2Glc), 3.33
(m, 4H, H-4Glc, –OMe), 2.75 (dd, 1H, J3eq,4 = 4.6 Hz,
Jgem = 13.2 Hz, H-3eqNeu), 2.10, 2.05, 2.00 (3s, 9H, 3
Ac), 1.71 (dd, 1H, J3ax,4 = 12.3 Hz, H-3axNeu); 13C
NMR (125 MHz, CDCl3) d 170.4, 169.9, 167.4, 150.7,
138.5, 138.1, 128.5, 128.4, 128.1, 128.0, 127.8, 127.7,
127.6, 100.3, 97.8, 81.9, 79.8, 77.8, 75.8, 74.9, 73.4,
73.0, 70.7, 69.4, 68.2, 64.3, 62.7, 55.0, 53.0, 51.2, 36.2,
20.8, 20.7, 20.6; MALDI-TOFMS m/z calcd for
[C45H53NO17+Na]+: 902.32. Found: 902.31.
72.9, 70.9, 70.6, 70.5, 68.4, 66.6, 64.0, 62.8, 53.1, 51.1,
36.6, 26.1, 26.0, 25.0, 24.6, 21.0, 20.9, 20.8; MALDI-
TOFMS m/z calcd for [C29H41NO17+Na]+: 698.22.
Found: 698.29.
1
3.10.2. b-Isomer. [a]D À8.8 (c 1.0, CHCl3); H NMR
(400 MHz, CDCl3) d 6.85 (s, 1H, NH), 5.60 (m, 1H,
H-8Neu), 5.49 (d, 1H, J1,2 = 5.1 Hz, H-1Gal), 4.97 (dt,
1H, J3eq,4 = 4.4 Hz, J3ax,4 = J4,5 = 10.2 Hz, H-4Neu),
4.64 (dd, 1H, J2,3 = 7.8 Hz, J3,4 = 2.3 Hz, H-3Gal), 4.57
(m, 1H, H-6Neu, H-7Neu), 4.49 (dd, 1H, J8,9a = 3.0 Hz,
Jgem = 12.1 Hz, H-9aNeu), 4.33 (m, 2H, H-2Gal, H-4Gal),
4.28 (dd, 1H, J8,9b = 5.5 Hz, H-9bNeu), 4.03 (m, 1H,
H-5Gal), 3.75 (m, 5H, H-5Neu, COOMe, H-6aGal), 3.42
(dd, 1H, J5,6b = 5.2 Hz, Jgem = 8.0 Hz, H-6bGal), 2.57
(dd, 1H, Jgem = 13.0 Hz, H-3eqNeu), 2.11, 2.09 and 2.08
(3s, 9H, 3 Ac), 1.66 (dd, 1H, H-3axNeu), 1.57, 1.45,
1.34, 1.33 (4s, 12H, 2 –C(CH3)2); 13C NMR (100
MHz, CDCl3) d 170.4, 170.1, 166.5, 151.2, 109.2,
108.7, 99.0, 96.1, 72.7, 70.6, 70.5, 70.3, 67.5, 67.3, 64.9,
62.9, 60.8, 52.7, 5.07, 36.1, 26.0, 25.7, 24.8, 23.9, 20.8,
20.6; MALDI-TOFMS m/z calcd for [C29H41NO17+
Na]+: 698.22. Found: 698.24.
3.9. Methyl 2,3,4-tri-O-benzyl-6-O-(methyl 4,8,9-tri-O-
acetyl-5-amino-5-N,7-O-carbonyl-3,5-dideoxy-D-glycero-
b-D-galacto-2-nonulopyranosylonate)-a-D-glucopyran-
oside (8b)
[a]D +32.1 (c 2.0, CHCl3); 1H NMR (600 MHz, CDCl3)
d 7.38–7.26 (m, 15H, 3 Ph), 6.80 (s, 1H, NH), 5.59 (m,
1H, H-8Neu), 5.05 (dt, 1H, J3eq,4 = 4.8 Hz, J3ax,4
=
J4,5 = 10.3 Hz, H-4Neu), 4.96 (d, 1H, –CH2Ph), 4.91 (d,
1H, –CH2Ph), 4.79 (d, 1H, –CH2Ph), 4.76 (d, 1H,
–CH2Ph), 4.64 (2d, 2H, 2 –CH2Ph), 4.61 (d, 1H,
J1,2 = 3.4 Hz, H-1Glc), 4.48 (m, 2H, H-7Neu, H-9aNeu),
4.28 (m, 2H, H-6Neu, H-9bNeu), 3.96 (t, 1H, J2,3
=
,
3.11. Methyl 2,3-di-O-benzyl-6-O-(methyl 4,8,9-tri-O-
acetyl-5-amino-5-N,7-O-carbonyl-3,5-dideoxy-D-glycero-
D-galacto-2-nonulopyranosylonate)-a-D-galactopyran-
oside (15)
J3,4 = 9.3 Hz, H-3Glc), 3.77–3.62 (m, 7H, H-5Neu
COOMe, H-5Glc, H-6aGlc, H-6bGlc), 3.55 (m, 2H,
H-2Glc, H-4Glc), 3.36 (s, 3H, –OMe), 2.57 (dd, 1H,
J3eq,4 = 4.6 Hz, Jgem = 13.0 Hz, H-3eqNeu), 2.11, 2.10,
2.07 (3s, 9H, 3 Ac), 1.68 (dd, 1H, J3ax,4 = 12.0 Hz, H-
3axNeu); 13C NMR (125 MHz, CDCl3) d 170.4, 170.3,
170.1, 166.5, 150.6, 138.4, 138.0, 128.5, 128.4, 128.3,
128.1, 128.0, 127.9, 127.7, 127.6, 99.0, 98.1, 81.8, 80.4,
75.8, 74.9, 73.5, 72.9, 70.5, 69.2, 67.7, 65.4, 63.0, 62.3,
55.3, 52.7, 51.3, 36.1, 20.9, 20.7; MALDI-TOFMS m/z
calcd for [C45H53NO17+Na]+: 902.32. Found: 902.34.
1
3.11.1. a-Isomer. [a]D +29.4 (c 0.8, CHCl3); H NMR
(400 MHz, CDCl3) d 7.36–7.26 (m, 10H, 2Ph), 6.84 (s,
1H, NH), 5.58 (m, 1H, H-8Neu), 4.79 (m, 2H, 2
–CH2Ph), 4.67 (m, 4H, H-4Neu, H-7Neu, 2 –CH2Ph),
4.58 (d, 1H, J1,2 = 3.2 Hz, H-1Gal), 4.46 (dd, 1H,
J8,9a = 3.0 Hz, Jgem = 12.1 Hz, H-9aNeu), 4.25 (dd, 1H,
J8,9b = 5.9 Hz, H-9bNeu), 4.06 (dd, 1H, J5,6 = 10.5 Hz,
J6,7 = 5.0 Hz, H-6Neu), 3.94 (br s, 1H, H-4Gal), 3.86-
3.10. 1,2:3,4-Diisopropylidene-6-O-(methyl 4,8,9-tri-O-
acetyl-5-amino-5-N,7-O-carbonyl-3,5-dideoxy-D-glycero-
D-galacto-2-nonulopyranosylonate)-a-D-galactose (14)
3.68 (m, 8H, H-5Neu, COOMe, H-2Gal, H-3Gal, H-5Gal
H-6aGal), 3.58 (dd, 1H, J5,6b = 5.5 Hz, Jgem = 9.1 Hz,
H-6bGal), 3.32 (s, 3H, –OMe), 2.75 (dd, 1H, J3eq,4
,
=
4.7 Hz, Jgem = 13.0 Hz, H-3eqNeu), 2.44 (s, 1H, –OHGal),
2.10, 2.07 and 2.06 (3s, 9H, 3 Ac), 1.73 (dd, 1H,
J3ax,4 = 11.9 Hz, H-3axNeu); 13C NMR (100 MHz,
CDCl3) d 170.5, 170.4, 169.8, 167.6, 151.3, 138.2,
138.0, 128.5, 128.4, 128.0, 127.9, 127.8, 127.7, 100.1,
98.3, 75.6, 73.5, 72.9, 72.8, 70.2, 68.3, 68.2, 67.8, 67.4,
63.9, 62.6, 55.2, 53.2, 51.1, 36.3, 20.7, 20.6; MALDI-
TOFMS m/z calcd for [C38H47NO17+Na]+: 812.27.
Found: 812.31.
1
3.10.1. a-Isomer. [a]D À9.7 (c 1.1, CHCl3); H NMR
(400 MHz, CDCl3) d 6.99 (s, 1H, NH), 5.58 (m, 1H,
H-8Neu), 5.45 (d, 1H, J1,2 = 5.0 Hz, H-1Gal), 4.69 (m,
2H, H-4Neu, H-7Neu), 4.57 (dd, 1H, J2,3 = 7.8 Hz,
J3,4 = 2.3 Hz, H-3Gal), 4.48 (dd, 1H, J8,9a = 3.0 Hz,
Jgem = 12.1 Hz, H-9aNeu), 4.27 (m, 2H, H-9bNeu
,
H-2Gal), 4.16 (dd, 1H, J4,5 = 7.8 Hz, H-4Gal), 4.06 (dd,
1H, J5,6 = 10.5 Hz, J6,7 = 5.0 Hz, H-6Neu), 3.84 (m,
4H, COOMe, H-5Gal), 3.75 (m, 2H, H-5Neu, H-6aGal),
3.56 (dd, 1H, J5,6b = 5.9 Hz, Jgem = 9.6 Hz, H-6bGal),
2.78 (dd, 1H, J3eq,4 = 4.5 Hz, Jgem = 13.2 Hz, H-3eqNeu),
1
3.11.2. b-Isomer. [a]D +13.5 (c 1.1, CHCl3); H NMR
(400 MHz, CDCl3) d 7.36–7.26 (m, 11H, NH, 2Ph),
5.58 (m, 1H, H-8Neu), 5.03 (dt, 1H, J3eq,4 = 4.6 Hz,
J3ax,4 = J4,5 = 10.5 Hz, H-4Neu), 4.75 (m, 3H, 3 –
CH2Ph), 4.63 (m, 3H, H-7Neu, H-1Gal, –CH2Ph), 4.46
(dd, 1H, J8,9a = 3.0 Hz, Jgem = 12.2 Hz, H-9aNeu), 4.26
2.11, 2.10, 2.08 (3s, 9H, 3 Ac), 1.78 (dd, 1H, J3ax,4
=
11.5 Hz, H-3axNeu), 1.50, 1.39 and 1.31 (3s, 12H, 2
–C(CH3)2); 13C NMR (100 MHz, CDCl3) d 170.7,
170.6, 170.0, 167.8, 151.6, 109.4, 108.7, 100.3, 96.3,

1592
H. Tanaka et al. / Carbohydrate Research 343 (2008) 1585–1593
(m, 2H, H-6Neu, H-9bNeu), 4.01 (br s, 1H, H-4Gal), 3.86–
7.5 Hz, H-8Neu), 5.24 (d, 1H, J3,4 = 3.4 Hz, H-4Gal
)
3.68 (m, 8H, H-5Neu
,
COOMe, H-2Gal
,
H-3Gal
,
=
4.79 (dt, 1H, J3eq,4 = 4.4 Hz, J3ax,4 = J4,5 = 10.7 Hz, H-
4Neu), 4.73 (dd, 1H, J6,7 = 5.8 Hz, H-7Neu), 4.67 (m,
3H, H-1Gal, 2 –CH2Ph), 4.53 (m, 3H, H-3Gal, 2 –CH2Ph),
H-5Gal, H-6aGal), 3.38 (dd, 1H, J5,6b = 5.9 Hz, Jgem
8.7 Hz, H-6bGal), 3.34 (s, 3H, –OMe), 3.21 (s, 1H, –
OHGal), 2.34 (dd, 1H, Jgem = 13.2 Hz, H-3eqNeu), 2.12,
2.09 and 2.08 (3s, 9H, 3 Ac), 1.73 (dd, 1H, H-3axNeu);
13C NMR (100 MHz, CDCl3) d 171.1, 170.4, 170.0,
166.5, 151.9, 138.3, 138.1, 128.5, 128.3, 128.0, 127.8,
127.7, 127.6, 99.2, 98.6, 77.5, 75.4, 73.5, 72.7, 72.6,
70.0, 67.5, 66.8, 66.6, 65.5, 62.7, 61.1, 55.4, 52.7, 51.0,
36.2, 21.0, 20.8, 20.7; MALDI-TOFMS m/z calcd for
[C38H47NO17+Na]+: 812.27. Found: 812.32.
4.43 (m, 2H, H-9aNeu, –CH2Ph), 4.27 (dd, 1H, Jgem
=
12.0 Hz, H-9bNeu), 4.07 (t, 1H, J5,6a = J5,6b = 5.7 Hz,
H-5Gal), 3.86 (s, 3H, COOMe), 3.77 (dd, 1H, J5,6
9.8 Hz, H-6Neu), 3.67 (dd, 1H, J1,2 = 3.5 Hz, J2,3
=
=
10.3 Hz, H-2Gal), 3.64 (t, 1H, H-5Neu), 3.47 (dd, 1H,
Jgem = 9.8 Hz, H-6aGal), 3.42 (dd, 1H, H-6bGal), 3.37
(s, 3H, –OMe), 2.73 (dd, 1H, Jgem = 13.4 Hz, H-3eqNeu),
2.07, 2.03 and 2.01 (3s, 12H, 4 Ac), 1.91 (dd, 1H,
H-3axNeu); 13C NMR (125 MHz, CDCl3) d 170.5,
170.4, 169.9, 169.5, 167.7, 151.3, 138.1, 138.0, 128.4,
128.3, 128.0, 127.8, 127.6, 100.2, 98.5, 75.0, 74.9, 73.3,
70.9, 70.7, 70.1, 70.0, 69.0, 67.9, 67.5, 62.4, 55.3, 53.4,
51.7, 35.4, 20.9, 20.8, 20.7, 20.6; MALDI-TOFMS m/z
calcd for [C40H49NO18+Na]+: 854.28. Found: 854.28.
3.12. Methyl (2-adamantyl 4,8,9-tri-O-acetyl-5-amino-5-
N,7-O-carbonyl-3,5-dideoxy-D-glycero-D-galacto-2-nonu-
lopyranosid)onate (16)
1
3.12.1. a-Isomer. [a]D +23.2 (c 0.6, CHCl3); H NMR
(500 MHz, CDCl3) d 6.81 (s, 1H, NH), 5.60 (m, 1H,
H-8), 4.73 (t, 1H, J6,7 = J7,8 = 5.8 Hz, H-7), 4.76 (m,
1H, H-4), 4.43 (dd, 1H, J8,9a = 3.5 Hz, Jgem = 12.1 Hz,
H-9a), 4.24 (dd, 1H, J8,9b = 6.9 Hz, H-9b), 3.96 (m,
2H, H-6, Adam), 3.83 (s, 3H, COOMe), 3.68 (t, 1H,
1
3.13.2. b-Isomer. [a]D +17.7 (c 0.3, CHCl3); H NMR
(500 MHz, CDCl3) d 7.37–7.26 (m, 10H, 2Ph), 5.75 (s,
1H, NH), 5.57 (m, 1H, H-8Neu), 5.31 (d, 1H, J3,4
2.3 Hz, H-4Gal), 4.93 (dt, 1H, J3eq,4 = 4.4 Hz, J3ax,4
=
=
J4,5 = J5,6 = 10.0 Hz, H-5), 2.87 (dd, 1H, J3eq,4
=
J4,5 = 10.7 Hz, H-4Neu), 4.81 (dd, 1H, J5,6 = 10.3 Hz,
J6,7 = 5.1 Hz, H-6Neu), 4.68 (dd, 1H, J7,8 = 8.6 Hz,
4.6 Hz, Jgem = 13.2 Hz, H-3eq), 2.12, 2.08 and 2.07 (3s,
9H, 3 Ac), 2.03–1.43 (m, 15H, H-3ax, Adam); 13C
NMR (125 MHz, CDCl3) d 170.7, 170.5, 169.6, 168.6,
151.6, 100.5, 78.0, 74.0, 70.6, 69.5, 68.0, 62.6, 53.0,
53.0, 51.7, 37.5, 37.4, 36.7, 34.1, 33.0, 31.5, 31.5, 27.2,
26.9, 21.0, 20.9, 20.8; MALDI-TOFMS m/z calcd for
[C27H37NO12+Na]+: 590.22. Found: 590.22.
H-7Neu), 4.63 (d, 1H, –CH2Ph), 4.60 (dd, 1H, J2,3
=
10.3 Hz, H-3Gal), 4.54 (d, 1H, J1,2 = 3.4 Hz, H-1Gal),
4.52 (d, 1H, –CH2Ph), 4.48 (dd, 1H, J8,9a = 2.8 Hz,
Jgem = 12.7 Hz, H-9aNeu), 4.40 (2d, 2H, 2 –CH2Ph),
4.27 (dd, 1H, J8,9b = 5.7 Hz, H-9bNeu), 4.06 (t, 1H,
J5,6a = J5,6b = 6.0 Hz, H-5Gal), 3.72 (t, 1H, H-5Neu),
3.67 (dd, 1H, H-2Gal), 3.54 (s, 3H, COOMe), 3.46 (dd,
1
3.12.2. b-Isomer. [a]D +8.5 (c 0.4, CHCl3); H NMR
1H, Jgem = 9.5 Hz, H-6aGal), 3.40 (dd, 1H, H-6bGal
)
(500 MHz, CDCl3) d 6.53 (s, 1H, NH), 5.60 (m, 1H,
3.31 (s, 3H, –OMe), 2.73 (dd, 1H, Jgem = 13.7 Hz,
H-3eqNeu), 2.11, 2.09, 2.06, 2.01 (4s, 12H, 4 Ac), 1.71
(dd, 1H, H-3axNeu); 13C NMR (125 MHz, CDCl3) d
170.7, 170.5, 170.3, 170.0, 165.9, 150.7, 138.1, 137.6,
128.5, 128.4, 128.1, 127.9, 127.8, 100.3, 98.6, 75.7,
75.6, 73.5, 72.8, 70.9, 70.1, 69.9, 68.2, 67.8, 67.7, 66.2,
63.0, 55.5, 52.4, 51.0, 36.6, 20.9, 20.7, 20.6; MALDI-
TOFMS m/z calcd for [C40H49NO18+Na]+: 854.28.
Found: 854.30.
H-8), 5.09 (dt, 1H, J3eq,4 = 4.6 Hz, J3ax,4 = J4,5
=
10.5 Hz, H-4), 4.60 (t, 1H, J6,7 = 5.2 Hz, J7,8 = 8.6 Hz,
H-7), 4.49 (dd, 1H, J8,9a = 2.8 Hz, Jgem = 12.0 Hz,
H-9a), 4.29 (dd, 1H, J8,9b = 5.7 Hz, H-9b), 4.20 (dd,
1H, J5,6 = 10.3 Hz, H-6), 3.77 (m, 2H, H-5, Adam),
3.73 (s, 3H, COOMe), 2.68 (dd, 1H, Jgem = 12.9 Hz,
H-3eq), 2.13, 2.11 and 2.09 (3s, 9H, 3 Ac), 1.85–1.47
(m, 15H, H-3ax, Adam); 13C NMR (125 MHz, CDCl3)
d 170.6, 170.5, 170.3, 167.7, 151.1, 99.7, 78.6, 73.0,
70.6, 67.9, 66.4, 63.1, 52.5, 51.4, 37.3, 37.2, 36.8, 36.6,
34.3, 32.7, 31.8, 31.4, 27.1, 26.9, 21.0, 20.9, 20.8; MAL-
DI-TOFMS m/z calcd for [C27H37NO12+Na]+: 590.22.
Found: 590.19.
3.14. Methyl 2,4,6-tri-O-benzyl-3-O-(methyl 4,8,9-tri-O-
acetyl-5-amino-5-N,7-O-carbonyl-3,5-dideoxy-D-glycero-
D-galacto-2-nonulopyranosylonate)-a-D-galactopyran-
oside (18)
1
3.13. Methyl 4-O-acetyl-2,6-di-O-benzyl-3-O-(methyl 4,
8,9-tri-O-acetyl-5-amino-5-N,7-O-carbonyl-3,5-dideoxy-
D-glycero-a-D-galacto-2-nonulopyranosylonate)-a-D-
galactopyranoside (17)
3.14.1. a-Isomer. [a]D +24.4 (c 0.5, CHCl3); H NMR
(400 MHz, CDCl3) d 7.33–7.25 (m, 15H, 3 Ph), 6.22 (s,
1H, NH), 5.59 (m, 1H, H-8Neu), 4.85 (d, 1H, –CH2Ph),
4.79 (dt, 1H, J3eq,4 = 4.6 Hz, J3ax,4 = J4,5 = 10.1 Hz,
H-4Neu), 4.73 (dd, 1H, J6,7 = 6.0 Hz, J7,8 = 3.2 Hz,
H-7Neu), 4.69 (m, 2H, H-1Gal, –CH2Ph), 4.58–4.50 (3d,
3H, 3 –CH2Ph), 4.41 (m, 3H, H-9aNeu, H-3Gal, –CH2Ph),
4.15 (dd, 1H, J8,9a = 7.8 Hz, Jgem = 11.9 Hz, H-9bNeu),
1
3.13.1. a-Isomer. [a]D +33.6 (c 0.6, CHCl3); H NMR
(500 MHz, CDCl3) d 7.33–7.26 (m, 10H, 2Ph), 6.67 (s,
1H, NH), 5.59 (dt, 1H, J7,8 = J8,9a = 3.7 Hz, J8,9b
=

H. Tanaka et al. / Carbohydrate Research 343 (2008) 1585–1593
1593
3.90 (m, 3H, H-6Neu, H-2Gal, H-5Gal), 3.82 (s, 3H,
References
COOMe), 3.76 (m, 1H, H-4Gal), 3.70 (dd, 1H, J4,5
=
J5,6 =10.1 Hz, H-5Neu), 3.54 (dd, 1H, J5,6a = 6.8 Hz,
Jgem = 9.6 Hz, H-6aGal), 3.46 (dd, 1H, J5,6b = 5.0 Hz,
1. Recent reviews: (a) Boons, B. J.; Demchenko, A. V. Chem.
Rev. 2000, 100, 4539–4565; (b) Halcomb, R. L.; Chappell,
M. D. J. Carbohydr. Chem. 2002, 21, 723–768; (c) Glonic,
D. P.; Gin, D. Y. Nature 2007, 446, 1000–1007.
2. (a) Kanie, O.; Kiso, M.; Hasegawa, A. J. Carbohydr.
Chem. 1988, 7, 501–506; (b) Hasegawa, A.; Ohki, H.;
Nagahama, T.; Ishida, H.; Kiso, M. Carbohydr. Res. 1991,
212, 277–281.
3. (a) Okamoto, K.; Kondo, T.; Goto, T. Tetrahedron Lett.
1986, 27, 5233–5236; (b) Ito, Y.; Ogawa, T. Tetrahedron
Lett. 1988, 29, 3987–3990; (c) Castro-Palomino, J. C.;
Tsvetkov, Y. E.; Schmidt, R. R. J. Am. Chem. Soc. 1998,
120, 5434–5440.
4. (a) Takahashi, T.; Tsukamoto, H.; Yamada, H. Tetra-
hedron Lett. 1997, 38, 8223–8226; (b) Haberman, J. M.;
Gin, D. Y. Org. Lett. 2001, 3, 1665–1668; (c) Ishiwata, A.;
Ito, Y. Synlett 2003, 1339–1343.
5. (a) Ando, H.; Koike, Y.; Ishida, H.; Kiso, M. Tetrahedron
Lett. 2003, 44, 6883–6886; (b) Ando, H.; Koike, Y.;
Koizumi, S.; Ishida, H.; Kiso, M. Angew. Chem., Int. Ed.
2005, 44, 6759–6763.
H-6bGal), 3.39 (s, 3H, OMe), 2.78 (dd, 1H, Jgem
=
13.8 Hz, H-3eqNeu), 2.17 (dd, 1H, H-3axNeu), 2.07, 1.99
and 1.96 (3s, 9H, 3 Ac); 13C NMR (100 MHz, CDCl3)
d 170.6, 170.5, 169.3, 167.7, 151.0, 138.7, 138.3, 138.0,
128.6, 128.4, 128.3, 128.2, 128.1, 127.8, 127.6, 127.5,
101.6, 98.4, 76.1, 74.6, 73.4, 73.3, 70.9, 69.6, 69.4, 67.5,
62.7, 55.1, 53.3, 51.7, 34.2, 20.9, 20.8, 20.5; MALDI-
TOFMS m/z calcd for [C45H53NO17+Na]+: 902.32.
Found: 902.34.
1
3.14.2. b-Isomer. [a]D +11.7 (c 0.5, CHCl3); H NMR
(400 MHz, CDCl3) d 7.39–7.28 (m, 15H, 3 Ph), 5.73 (s,
1H, NH), 5.54 (m, 1H, H-8Neu), 4.83 (dt, 1H, J3eq,4
=
4.5 Hz, J3ax,4 = J4,5 = 10.5 Hz, H-4Neu), 4.75 (d, 1H,
–CH2Ph), 4.65 (m, 2H, 2 –CH2Ph), 4.56 (m, 3H,
H-7Neu, H-1Gal, –CH2Ph), 4.47 (m, 4H, H-9aNeu
,
6. (a) Komba, S.; Galustian, C.; Ishida, H.; Feizi, T.;
Kannagi, R.; Kiso, M. Angew. Chem., Int. Ed. 1999, 38,
1131–1133; (b) De Meo, C.; Demchenko, A. V.; Boons, G.
J. J. Org. Chem. 2001, 66, 5490–5497.
7. Demchenko, A. V.; Boons, G. J. Tetrahedron Lett. 1998,
39, 3065–3068.
H-3Gal, 2 –CH2Ph), 4.24 (m, 3H, H-6Neu, H-9bNeu),
3.97 (dd, 1H, J5,6a = J5,6b = 6.9 Hz, H-5Gal), 3.91 (dd,
1H, J1,2 = 3.5 Hz, J2,3 = 10.4 Hz, H-2Gal), 3.81 (m, 1H,
H-4Gal), 3.72 (dd, 1H, J4,5 = J5,6 = 10.1 Hz, H-5Neu),
3.63–3.53 (m, 5H, COOMe, H-6aGal, H-6bGal), 3.30 (s,
3H, OMe), 2.84 (dd, 1H, Jgem = 13.7 Hz, H-3eqNeu),
2.10, 2.04 and 2.03 (3s, 9H, 3 Ac), 1.75 (dd, 1H, H-
3axNeu); 13C NMR (100 MHz, CDCl3) d 170.4, 170.1,
170.0, 166.0, 150.1, 138.2, 138.1, 137.7, 128.6, 128.3,
128.2, 127.9, 127.8, 127.7, 127.6, 127.1, 100.5, 98.6,
78.3, 75.1, 75.0, 73.4, 73.3, 72.8, 70.6, 69.3, 68.3, 67.5,
66.6, 62.9, 55.4, 52.5, 51.1, 36.3, 20.9, 20.7, 20.6; MAL-
DI-TOFMS m/z calcd for [C45H53NO17+Na]+: 902.32.
Found: 902.33.
8. Yu, C.-S.; Niikura, K.; Lin, C.-C.; Wong, C.-H. Angew.
Chem., Int. Ed. 2001, 40, 2900–2903.
9. Tanaka, K.; Goi, T.; Fukase, K. Synlett 2005, 2958–2962.
10. (a) Tanaka, H.; Nishiura, Y.; Takahashi, T. J. Am. Chem.
Soc. 2006, 128, 7124–7125; (b) Farris, M. D.; De Meo, C.
Tetrahedron Lett. 2007, 48, 1225–1227; (c) Crich, D.; Li,
W. J. Org. Chem. 2007, 72, 2387–2391.
11. Crich, D.; Wu, B. Tetrahedron 2008, 64, 2042–2047.
12. Ohno, H.; Hamaguchi, H.; Tanaka, T. Org. Lett. 2000, 2,
2161–2163.
13. Cao, S.; Meunier, S. J.; Andersson, F. O.; Letellier, M.;
Roy, R. Tetrahedron: Asymmetry 1994, 5, 2303–2312.
14. Veeneman, G. H.; van Leeuwen, S. H.; van Boom, J. H.
Tetrahedron Lett. 1990, 31, 1331–1334.
15. Xia, J.; Alderfer, J. L.; Piskorz, C. F.; Matta, K. L. Chem.
Eur. J. 2001, 7, 356–367.
Acknowledgments
16. (a) Dabrowski, U.; Friebolin, H.; Brossmer, R.; Supp, M.
Tetrahedron Lett. 1979, 20, 4637–4640; (b) Paulsen, H.;
Tietz, H. Angew. Chem., Int. Ed. Engl. 1982, 21, 927–928.
17. Ito, Y.; Ogawa, T. Tetrahedron Lett. 1988, 29, 1061–1064.
18. (a) Code’e, J. D. C.; van den Bos, L. J.; Litjens, R. E. J.
N.; Overkleeft, H. S.; van Boeckel, C. A. A.; van Boom, J.
H.; van der Marel, G. A. Tetrahedron 2004, 60, 1057–1064;
(b) Crich, D.; Li, W. Org. Lett. 2006, 8, 959–962.
19. (a) Ercegovic, T.; Meijer, A.; Magnusson, G.; Ellervik, U.
Org. Lett. 2001, 3, 913–915; (b) Meijer, A.; Ellervik, U. J.
Org. Chem. 2004, 69, 6249–6256.
We greatly thank Dr. Yukishige Ito (RIKEN) for pro-
viding the sialic acid. This work was supported by
MEXT of Japan (Grant-in-Aid for Scientific Research
to H.A., No. 16780083) and Mitsubishi Chemical
Corporation Fund (H.A.).
Supplementary data
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.carres.
2008.05.005.