A Highly Practical Synthesis of Sulfated Lewis X: One-Pot, Two-Step Glycosylation Using "Armed/Disarmed" Coupling and Selective Benzoylation and Sulfation

Article abstract of DOI:10.1021/jo970076m

In spite of the several attractive biological activities of the Le^x, sLe^x, and sulfated Le^x derivatives, there are still limitations in their practical syntheses. One of the most difficult problems is the many steps required for their syntheses. Therefore, we investigated simple constructions of the Le^x analogs and succeeded in establishing highly practical syntheses of the Le^x and sulfated Le^x analogs. Especially, the "armed/disarmed" method allowed the first synthesis of Le^x derivatives by a one-pot, two-step glycosylation. This synthetic strategy could be an applicable and useful method for oligosaccharide constructions of Le^x, sulfated Le^x, and other derivatives.

Full text of DOI:10.1021/jo970076m

6876
J . Org. Chem. 1997, 62, 6876-6881
A High ly P r a ctica l Syn th esis of Su lfa ted Lew is X: On e-P ot,
Tw o-Step Glycosyla tion Usin g “Ar m ed /Disa r m ed ” Cou p lin g a n d
Selective Ben zoyla tion a n d Su lfa tion
Takahiro Tsukida, Masahiro Yoshida, Kiriko Kurokawa, Yoshiyuki Nakai, Toshio Achiha,
Takao Kiyoi, and Hirosato Kondo*
Department of Medicinal Chemistry, Kanebo Ltd., New Drug Research Laboratories,
1-5-90 Tomobuchi-Cho, Miyakojima-Ku, Osaka 534, J apan
Received J anuary 15, 1997X
In spite of the several attractive biological activities of the Lex, sLex, and sulfated Lex derivatives,
there are still limitations in their practical syntheses. One of the most difficult problems is the
many steps required for their syntheses. Therefore, we investigated simple constructions of the
Lex analogs and succeeded in establishing highly practical syntheses of the Lex and sulfated Lex
analogs. Especially, the “armed/disarmed” method allowed the first synthesis of Lex derivatives
by a one-pot, two-step glycosylation. This synthetic strategy could be an applicable and useful
method for oligosaccharide constructions of Lex, sulfated Lex, and other derivatives.
In tr od u ction
matic and enzymatic methods is not commercially avail-
able. A major disadvantage of the enzymatic methods
is that the narrow substrate specificities of the glycosyl-
transferases impede the synthesis of various modified
oligosaccharides.4b
Recently, some quite interesting biological properties
of oligosaccharides have been revealed, and exciting
studies have indicated the involvement of selectin-
oligosaccharide interactions in various inflammatory
diseases.1 Since Phillips et al.2 reported that the tet-
rasaccharide sialyl Lewis x antigenic determinant (sLex)
is a native ligand for E-selectin, which is a member of
the family of cell adhesion molecules, the synthesis of
the sLex oligosaccharide has attracted the interest of
organic chemists, because of the low abundance of sLex
from natural sources. The total synthesis of sLex has
been reported by several groups.3 One of the most
attractive strategies for the synthesis of sLex incorporates
enzymatic and chemoenzymatic approaches,4 which in-
volve the stereospecific and regiospecific construction of
the oligosaccharides. However, these approaches would
be mainly limited to the synthesis of the oligosaccharide,
because the key enzyme used for the above chemoenzy-
On the other hand, recent research has also focused
on the construction of Lex analogs with a sialic acid of
sLex replaced by more simple functional groups, e.g.
sulfuric acid,5 phosphoric acid,6 and carboxylic acid.7 We
have found that a 3′-sulfated Lex analog (1) with a
branched alkyl chain, 2-tetradecylhexadecyl, was an
effective selectin inhibitor both in vitro and in vivo.8 In
addition, we have investigated the binding mode between
compound 1 and E-selectin using the molecular dynamic
method and found that the 2-tetradecylhexadecyl group
of compound 1 played an important role in the interaction
with E-selectin.9
It has been reported that the total synthesis of com-
pound 1 involves 17 reaction steps from the starting
material, lactose.5a There are still limitations for the
synthesis of compound 1 at the practical level, because
of problems involving the poor selectivity of the benzoy-
lation and the low yield from the eight-steps of gly-
cosylation.5a Therefore, to establish a practical synthesis
of compound 1, we focused on the following three points:
(1) the optimization of selective benzoylation, (2) a one-
pot glycosylation based on the “armed/disarmed” coupling
method, and (3) the establishment of selective sulfation.
This paper describes the highly practical synthesis for
oligosaccharides such as the Lex and sulfated Lex deriva-
X Abstract published in Advance ACS Abstracts, September 15, 1997.
(1) (a) Bevilacqua, M. P.; Pober, J . S.; Mendrick, D. L.; Cotran, R.
S.; Gimbrone, M. A.; Proc. Natl. Acad. Soc. U.S.A. 1987, 84, 9238-
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Singhal, A. K.; Hakomori, S.-T.; Paulson, J . C. Science 1990, 250,
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Soc. 1992, 114, 8331-8333. (g) Danishefsky, S. J .; Gervay, J .; Peterson,
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S0022-3263(97)00076-5 CCC: $14.00 © 1997 American Chemical Society

Highly Practical Synthesis of Sulfated Lewis X
J . Org. Chem., Vol. 62, No. 20, 1997 6877
Sch em e 1. Syn th etic Str a tegy for Su lfa ted LeX An a logs
Sch em e 2
tives, which involves a “one-pot” synthesis of two glyco-
sidic linkages with good stereocontrol.
byproducts, the 2,6,6′-O-benzoyl derivative 5a, the 2,3,6,6′-
O-benzoyl derivative 7a , and the perbenzoyl derivative
8a . Compound 5a would be a precursor for compounds
6a and 7a , respectively (Scheme 2). The product ratio
of 5a , 6a , 7a , and 8a was 4:10:3:2 from HPLC data.11
These reaction conditions for the benzoylation are not
sufficient to give the 2,6,2′,6′-O-benzoyl derivative 6,
selectively. Therefore, improvements in Hasegawa’s
method6a were pursued to obtain the desired compound
6, selectively. Namely, we studied several reaction
conditions, e.g., the solvent effect, the reaction temper-
ature, and the amount of benzoyl chloride, based on
Hasegawa’s method, which specified the solvent (CH2Cl2),
the reaction temperature (-40 °C), and the amount of
benzoyl chloride (5 equiv).
Table 1 summarizes the optimization studies for the
benzoylation of 4a . In CHCl3, the formation of 7a was
prior to that of 6a . In THF and toluene, compound 6a
was preferentially produced 20-100-fold more as com-
pared to 7a ; however, the conversion ratio from 5a to 6a
seemed to be low (run A). Next, the solvents were chosen
to be THF and toluene, and then various reaction
Resu lts a n d Discu ssion
Our synthetic strategy for the 3′-sulfated Lex derivative
1 is to establish methods for the efficient incorporation
of the fucose residue, a branched alkyl chain, and the
sulfuric acid group to lactose, which is commercially
available, as illustrated in Scheme 1.
Selective Ben zoyla tion . 2,6,2′,6′-O-Benzoyl lactose
derivatives (6a -c) could be important acceptors for the
efficient construction of a Lex skeleton. Hasegawa et al.5a
reported that 2,6,2′6′-O-benzoyllactose (6c, R ) OSE;
2-(trimethylsilyl)ethoxy group) was obtained by the ben-
zoylation of the corresponding derivative to a 3′,4′-O-
isopropylidene derivative (4c, R ) OSE). In a similar
manner to Hasegawa’s method, we synthesized a 3′,4′-
O-isopropylidene derivative (4a , R ) OBn)10 from lactose
and then tried the benzoylation of 4a . The desired
product 6a was isolated in a 45% yield together with the
(10) 1H NMR data of the compound 4a ; 1H NMR (CDCl3) δ 1.26 (s,
3H), 1.40 (s, 3H), 3.07-3.14 (m, 1H), 3.20-3.37 (m, 4H), 3.54-3.64
(m, 3H), 3.74-3.86 (m, 2H), 3.95-4.0 (t, 1H, J )7.0 Hz), 4.12 (dd, 1H,
J ) 1.5, 7.1Hz), 4.30 (dd, 2H, J ) 8.0, 9.3 Hz), 4.58 (d, 1H, J ) 12.2
Hz), 4.83 (d, 1H, J ) 12.2 Hz), 7.26-7.41 (m, 5H).
(11) HPLC condition: column (ODS), elution solvent (0.1% TFA:
CH3CN ) 1:5), retention time (min); 4.5 for compound 5a , 5.7 for
compound 7a , 9.0 for compound 6a , 11.2 for compound 8a .

6878 J . Org. Chem., Vol. 62, No. 20, 1997
Tsukida et al.
Sch em e 3
Ta ble 1. Op tim iza tion Stu d ies for th e Ben zoyla tion
of 4a
Ta ble 2. Glycosyla tion Usin g “Ar m ed /Disa r m ed ”
Cou p lin g
product ratioa
A. Stepwise Glycosylation
Bz-Cl temp time
run solvent (equiv) (°C)
(h)
5a
6a
7a
8a
0.32
6b (equiv)
9 (equiv)
temp (°C)
time (h)
10 (%)a
Ab CHCl3
5
5
5
5
-45
-45
-45
-20
3
3
3
3
5.9
31
21
19
1
1
1
1
2.2
1
1
1
1.5
-20
-20
1
1
55
83
A
A
A
THF
toluene
CH3CN
<0.01 <0.01
0.08 <0.01
0.33 <0.01
10 (equiv)
11 (equiv)
temp (°C)
time (h)
12 (%)a
Bc THF
5
5
5
5
5
5
-45
-20
0
-45
-20
0
3
3
3
3
3
3
31
1
1
1
1
1
1
<0.01 <0.01
1
1
2
2
0
-20
1
1
53b
86
B
B
B
B
B
THF
THF
toluene
toluene
toluene
5.3
2.5
21
5.7
2.5
0.10
0.10
0.01
0.02
B. One-Pot, Two-Step Glycosylation
6b (equiv) 9 (equiv) 11 (equiv) temp (°C) time (h) 12 (%)a
0.08 <0.01
0.08
0.10
0.02
0.04
1
1
1.5
1.5
2
2
-20
-20
0.5 + 0.5
1 + 0.5
66
80
Cd THF
5
8
5
8
0
0
0
0
3
3
3
3
2.5
0.57
1.4
1
1
1
1
0.10
0.18
0.10
0.05
0.02
0.08
0.04
0.11
C
C
C
THF
toluene
toluene
a
b
Isolated yield. Byproduct (12′) was obtained together with
12.
0.08
applicability. There are some examples14 of glycosylation
based on the “armed/disarmed” principle; however, at the
present stage little is known concerning the syntheses
of the Lex, sLex, and sulfated Lex derivatives using the
“armed/disarmed” method. Therefore, we investigated
the practical glycosylation involving the “armed/dis-
armed” coupling, e.g., fucosylation, followed by the in-
corporation of an alkyl chain on the 2,6,2′,6′-O-benzoyl-
lactose derivative.
In the present work, we chose a phenyl 2,3,4-tri-O-
benzyl-thio-â-fucoside (9) as the armed donor and a
phenyl 2,6,2′,6′-O-benzoyl-thio-â-lactoside (6b) as the
disarmed acceptor, because both compounds were easily
prepared and are stable solids (Scheme 3). To produce
the desired R-fucoside, the mixture of perbenzylated
phenylthiofucoside 9 (1.5 equiv) and 6b (1 equiv) in
chloroform was treated with N-iodosuccinimide (NIS,
2.25 equiv) and trifluoromethanesulfonic acid (TfOH, 0.75
equiv) in the presence of 4 Å molecular sieves at -20 °C
to isolate the desired R-linked product 10 in an 83% yield
(Table 2). This reaction proceeded in a stereospecific
manner, because no â-glycoside was isolated. In addition,
it was of interest that the glycosyl donor 9 was selectively
activated in the presence of the activator, NIS-TfOH.
This selective activation is predominantly dependent on
the C2 substituents.13b Namely, the activation of the
phenylthio-fucoside 9, with a C2 electron-donating group
(OCH2Ph), is prior to that of the phenylthio-lactoside 6b,
with a C2 electron-withdrawing group (OCOPh).
a
Product ratio was determined by HPLC. HPLC condition:
b
ODS column, 0.1% TFA: CH3CN ) 1:5, see ref 9. Solvent effect.
c Temperature effect. Amount of effect of benzoyl chloride.
d
temperatures were individually tested (run B). The ratio
of 5a decreased with increasing reaction temperature in
both THF and toluene; however, the ratio of 5a was still
similar to that of 6a . Then, to accelerate the conversion
ratio from 5a to 6a , the amount of benzoyl chloride was
investigated (run C). As a result, the conversion ratio
from 5a to 6a increased with increasing benzoyl chloride.
Especially, in toluene the desired compound 6a was
obtained selectively. In addition, the reaction of 4a 10 and
4b12 with 8 equiv of benzoyl chloride in toluene at 0 °C
afforded the 2,6,2′,6′-O-benzoyl derivatives 6a ,b in 73%
and 77% yields, respectively.
Glycosyla t ion Usin g “Ar m ed /Disa r m ed ” Cou -
p lin g. A “armed/disarmed” principle would be one of the
most useful methods for the synthesis of the oligosac-
charides, because glycosylation using “armed/disarmed”
coupling allows the construction of continuous glycosidic
bonds. Fraser-Reid et al.13 reported that the “armed/
disarmed” coupling for glycosylation could have general
(12) Nagao, Y.; Nukada, T.; Ikeda, K.; Achiwa, K. Chem. Pharm.
Bull. 1995, 43, 1536-1542.
(13) (a) Mootoo, D. R.; Konradsson, P.; Udodong, U. E.; Fraser-Reid,
B. J . Am. Chem. Soc. 1988, 110, 5583-5584. (b) Fraser-Reid, B.; Wu,
Z.; Udodong, U. E.; Ottosson, H. J . Org. Chem. 1990, 55, 6068-6070.
(c) Fraser-Reid, B.; Udodong, U. E.; Wu, Z.; Ottoson, H.; Merritt, R.;
Rao, C. S.; Roberts, C. Synlett 1992, 927-942. (d) Konradsson, P.;
Mootoo, D. R.; McDevitt, R. E.; Fraser-Reid, B. J . Chem. Soc., Chem.
Commun. 1990, 270-272. (e) Konradsson, P.; Udodong, U.; Fraser-
Reid, B. Tetrahedron Lett. 1990, 31, 4313-4316. (f) Konradsson, P.;
Fraser-Reid, B. J . Chem. Soc. Chem. Commun. 1989, 1124-1125. (g)
Roberts, C.; Madsen, R.; Fraser-Reid, B. J . Am. Chem. Soc. 1995, 117,
1546-1553. (h) Fraser-Reid, B.; Wu, Z.; Andrews, C. W.; Skowronski,
E.; Bowen, J . P. J . Am. Chem. Soc. 1991, 113, 1434-1435. (i) Madsen,
R.; Udodong, U.; Roberts, C.; Mootoo, D.; Mootoo, U. D. R.; Konradsson,
P.; Fraser-Reid, B. J . Am. Chem. Soc. 1995, 117, 1554-1565. (j) Boons,
G.-J . Tetrahedron 1996, 52, 1095-1121.
To complete the following glycosidic linkage with a
branched alkyl chain (11), the glycosylation of the donor
(14) (a) Veeneman, G. H.; van Boom, J . H. Tetrahedron Lett. 1990,
31, 275-278. (b) Boons, G.-J .; Grice, P.; Leslie, R.; Ley, S. U.; Yeung,
L. L. Tetrahedron Lett. 1993, 34, 8523-8526. (c) Veeneman, G. H.;
van Leeuwen, S. H.; van Boom, J . H. Tetrahedron Lett. 1990, 31, 1331-
1334. (d) Zuurmond, H. M.; van der Laan, S. C.; van der Marel, G. A.;
van Boom, J . H. Carbohydr. Res. 1991, 215, C1.

Highly Practical Synthesis of Sulfated Lewis X
J . Org. Chem., Vol. 62, No. 20, 1997 6879
Sch em e 4
Sch em e 5
10 and the acceptor 11 was investigated. As shown in
Table 2, the reaction temperature crucially affected the
yield of the desired product 12. When the glycosylation
reaction was carried out at 0 °C, the desired product 12
was isolated in a 53% yield together with the byproduct
12′, which had cleaved the fucosyl bond from 12. Thus
the trisaccharide 10 was activated with NIS (2 equiv)-
TfOH (0.5 equiv) and was added to 11 (2 equiv) in
chloroform in the presence of 4 Å molecular sieves at -20
°C. The desired â-linked product 12 was isolated in an
86% yield. This reaction was stereospecifically controlled
by the neighboring effect of the C2 benzoyl group of 10
to give only the â-glycoside.
On the other hand, to optimize the glycosylation using
the “armed/disarmed” coupling for the construction of the
Lex derivative 12, a one-pot, two-step glycosylation was
investigated. Recently, several methods have been re-
ported to perform sequential glycosylation as a one-pot
procedure.15 Kahne et al.15a reported a one-pot glycosy-
lation method that is based on activation of anomeric
sulfoxides with Tf2O or TfOH. Takahashi et al.15b
reported the synthesis of an elicitor-active hexa-â-D-
glucopyranosyl-D-glucitol, based on a one-pot, two-step
glycosylation, using a combination of different leaving
groups, trichloroacetimidate (-O(CNH)CCl3) and phe-
nylthio groups (-SPh), and different activators, TMSOTf
and NIS-TfOH, respectively. However, there have been
few reports concerning the synthesis of Lex derivatives
based on a one-pot, two-step glycosylation using the same
leaving group, the SPh group, and the same activator,
NIS-TfOH. As a result, the selective activation of the
armed donor 9 with NIS (1.5 equiv)-TfOH (0.5 equiv), in
the presence of the disarmed acceptor 6b and 4 Å
molecular sieves in chloroform at -20 °C, resulted in the
formation of the phenylthio-trisaccharide 10. To the
reaction mixture was added the acceptor 11, and then
another phenylthio group was activated with NIS (2
equiv)-TfOH (0.5 equiv) at the same temperature to give
the desired product 12 in an 80% yield, based on the
perbenzylfucoside 9. Hydrogenolysis of the benzyl groups
in the product 12 and subsequent acetylation with
Ac2O in pyridine, followed by treatment with 80% AcOH,
afforded the 3′,4′-dihydroxyl derivative 13 in a 79% yield
(Scheme 4).
Selective Su lfa tion . Regioselective sulfation has
been reported previously.6 For example, chemical syn-
theses have involved extensive protection methods to
produce a hydroxyl group for sulfation and have used
lengthy syntheses. Recently, Flitsch et al.16 reported the
regioselective sulfation of disaccharides using dibutyl-
(15) (a) Raghavan, S.; Kahne, D. J . Am. Chem. Soc. 1993, 115,
1580-1581. (b) Yamada, H.; Harada, T.; Takahashi, T. J . Am. Chem.
Soc. 1994, 116, 7917-7919. (c) Ley, S. V.; Priepke, H. W. M. Angew.
Chem., Int. Ed. Engl. 1994, 33, 2292-2294.
(16) Guilbert, B.; Davis, N. J .; Flitsch, S. L. Tetrahedron Lett. 1994,
35, 6563-6566.

6880 J . Org. Chem., Vol. 62, No. 20, 1997
Tsukida et al.
(d, 1H, J ) 10.1 Hz, H-1 of Gal), 4.86 (dd, 1H, J ) 2.7,9.7 Hz),
5.18 (dd, 1H, J ) 9.2 Hz, H-2 of Gal), 5.34 (t, 1H, H-2 of Glu),
stannylene acetals. This methodology could be useful for
the selective activation of the 3′-hydroxyl group of a
sugar. However, from a practical point of view, a
regioselective sulfation without an organometal, such as
organotin, would be a more useful method. In addition,
the C3 position of the galactosyl residue seems to be
relatively reactive as compared to the C4 position of
galactose.17 Therefore, we investigated the regioselective
synthesis of a 3′-sulfated Lex from the 3′,4′-diol trisac-
charide 13 with a sulfate reagent, a sulfur trioxide/
pyridine complex. When compound 13 was reacted with
the sulfur trioxide/pyridine complex in DMF at 0 °C, it
was interesting to note that the less reactive C4 hydroxyl
group was sulfated to afford the 4′-sulfated Lex derivative
14 in a 73% yield. This reaction was a regioselective
sulfation, because neither the 3′-sulfated Lex derivative
nor the 3′, 4′-disulfated Lex 15 were isolated. When a
similar sulfation of compound 13 was carried out at room
temperature, only the 3′,4′-disulfated Lex 15 was isolated,
in a 73% yield. On the other hand, to produce selectively
the 3′-sulfated Lex derivative 17 from 13, compound 13
was first selectively acetylated at the C4 position accord-
ing to the previous report,18 to provide the 4′-acetyl Lex
derivative 16 in a 95% yield. Subsequently, compound
16 was reacted with the sulfur trioxide/pyridine complex
in DMF at 0 °C to afford the 3′-sulfated Lex 17 in a 90%
yield. These sulfated derivatives, 17, 14, and 15, were
hydrolyzed under basic conditions to afford compounds
1, 2, and 3, respectively.
7.00-8.20 (m, 25H, 5Ph). Anal. Calcd for C49H46O14
S
(890.95): C, 66.06; H, 5.20. Found: C, 65.66 ; H, 5.16.
Ben zyl O-(2,6-Di-O-ben zoyl-3,4-O-isop r op ylid en e-â-D-
ga la ctop yr a n osyl)-(1-4)-2,6-d i-O-ben zoyl-1 -â-D-glu cop y-
r a n osid e (6a ). According to the synthesis of 6b, 6a was
isolated in 73% yield: mp 166-168 °C; [R]D -4.0° (c ) 0.26,
1
CHCl3); H NMR (CDCl3) δ 1.34 (s, 3H), 1.62 (s, 3H), 3.55-
3.80 (m, 2H), 3.94 (dd, J ) 8.2, 9.5 Hz, 1H), 4.15-4.30 (m,
3H), 4.35-4.50 (m, 3H), 4.54 (d, J ) 12.6 z, 1H), 4.66 (d, J )
8.1 Hz, 1H), 4.76 (d, J ) 12.6 Hz, 1H), 5.28 (dd, J ) 8.1, 9.5
Hz, 1H), 5.34 (t, J ) 7.5 Hz, 1H), 7.0-8.15 (m, 25H, Ph-H).
Anal. Calcd for C50H48O15 (888.92): C, 67.56; H, 5.44.
Found: C, 67.23 ; H, 5.52.
P h en yl O-(2,6-Di-O-ben zoyl-3,4-O-isop r op ylid en e-â-D-
galactopyr an osyl)-(1-4)-O-[(2,3,4-tr i-O-ben zyl-r-L-fu copy-
r a n osyl)-(1-3)]-2,6-d i-O-ben zoyl-1-th io-â-D-glu cop yr a n o-
sid e (10). To a solution of 6b (600 mg, 0.67 mM) and 919 (540
mg, 1.03 mM) in CHCl3 (6 mL) was added 4 Å molecular sieves
(MS-4Å, 960 mg), and the mixture was stirred for 6 h at room
temperature and then cooled to -20 °C. N-Iodosuccinimide
(NIS, 350 mg) and trifluoromethanesulfonic acid (TfOH, 77
mg) were added to the mixture, and this was stirred for 1 h at
-20 °C. The precipitate was filtered off, and the filtrate was
successively washed with aqueous NaHCO3, aqueous Na2S2O3
and water, dried (MgSO4), and concentrated. Column chro-
matography (2:7 AcOEt-hexane) of the residue on silica gel
gave 10 (730 mg, 83%) as an amorphous mass: [R]D -3.5° (c
1
) 0.17, CHCl3); H NMR (CDCl3) δ 1.30 (d, 3H, J ) 6.2 Hz,
H-6 of Fuc), 1.31, 1.50 (2s, 6H, Me2C), 3.7-3.8 (m, 1H, H-4 of
Fuc), 3.90 (dd, 1H, J ) 3.7 Hz, J ) 10.1 Hz, H-2 of Fuc), 4.00
(t, 1H, J ) 9.5 Hz, H-3 of Fuc), 4.50 (d, 1H, J ) 8.8 Hz, H-1 of
Glu), 4.67 (d, 1H, J ) 7.4 Hz, H-1 of Gal), 5.23 (dd, 1H, J )
8.7 Hz, H-2 of Gal), 5.39 (d, 1H, H-1 of Fuc), 5.43 (dd, 1H, H-2
In conclusion, we succeeded in establishing a highly
practical synthesis by the combination of three key
reactions: (1) a selective benzoylation, (2) a glycosylation
using “armed/disarmed” coupling, and (3) a selective
sulfation. Especially, the “armed/disarmed” method al-
lowed the first synthesis of Lex derivatives by a one-pot,
two-step glycosylation. Thus, this synthetic methodology
could be an applicable and useful technique for the
construction of Lex and sulfated Lex derivatives.
of Glc), 6.94-8.20 (m, 40H, 8Ph). Anal. Calcd for C76H74O18
(1307.5): C, 69.82; H, 5.70. Found: C, 69.76 ; H, 5.61.
S
2-Tetr a d ecylh exa d ecyl O-(2,6-Di-O-ben zoyl-3,4-O-iso-
p r op ylid en e-â-D-ga la ctop yr a n osyl)-(1-4)-O-[(2,3,4-tr i-O-
b en zyl-r-L-fu cop yr a n osyl)-(1-3)]-2,6-d i-O-b en zoyl-â-D-
glu cop yr a n osid e (12). To a solution of 1120 (260 mg, 0.59
mM) and 10 (387 mg, 0.30 mM) in CHCl3 (3.3mL) was added
4 Å molecular sieves (MS-4Å, 390 mg), and the mixture was
stirred for 8 h at room temperature and then cooled to -20
°C. NIS (200 mg) and TfOH (36 mg) were added to the
mixture, and this was stirred for 1 h at -20 °C. The
precipitate was filtered off and the filtrate was successively
washed with aqueous NaHCO3, aqueous Na2S2O3, and water,
dried (MgSO4), and concentrated. Column chromatography
(1:6 AcOEt-hexane) of the residue on silica gel gave 12
(416mg, 86%) as an amorphous mass: [R]D +1.9° (c ) 0.58,
CHCl3): 1H NMR (CDCl3) δ 0.75-0.90 (m, 6H, 2MeCH2), 1.00-
1.50 (m, 59H), 3.07 (dd, 1H, J gem ) 9.4 Hz, J 1,2 ) 6.6 Hz, H-1
of lipophilic part), 3.65 (dd, 1H, J 1′,2 ) 5.0 Hz, H-1′ of lipophilic
Exp er im en ta l Section
Specific rotations were determined with a J asco DIP-370
digital polarimeter at 25 °C. Melting points were determined
with a Buchi capillary melting point apparatus, Model 535;
all melting points are uncorrected. 1H NMR spectra were
recorded on a spectrometer with TMS as an internal reference
in a solution of CDCl3 and DMSO-d6. Mass spectra were
recorded using a MALDI-TOF Voyager-RP (PerSeptive Bio-
systems) with a negative mode. Elemental analyses were
performed with a Yanagimoto CHN-CORDER MT-3.
part), 3.70-3.85 (m, 2H), 3.91 (dd, 1H, J 1,2 ) 3.7 Hz, J 2,3
)
10.2 Hz, H-2 of Fuc), 4.22 (dd, 1H, J 3,4 ) 3.7 Hz, H-3 of Fuc),
4.24 (m, 1H, H-3 of Gal), 4.27 (t, 1H, J 2,3 ) J 3,4 ) 9.6 Hz, H-3
of Glc), 4.36 (d, 1H, J 1,2 ) 8.0 Hz, H-1 of Glc), 4.49 (d, 1H, J 1,2
) 7.9 Hz, H-1 of Gal), 4.87 (m, 1H, H-5 of Fuc), 5.24 (t, 1H,
J 1,2 ) J 2,3 ) 7.7 Hz, H-2 of Gal), 5.40 (dd, 1H, H-2 of Glc), 5.43
(d, 1H, H-1 of Fuc), 6.85-8.20 (m, 35H, 7Ph). Anal. Calcd
for C100H130O19 (1636.1): C, 73.41; H, 8.01. Found: C, 73.30;
H, 7.86.
2-Tetr a d ecylh exa d ecyl O-(2,6-Di-O-ben zoyl-3,4-O-iso-
p r op ylid en e-â-D-ga la ctop yr a n osyl)-(1-4)-O-[(2,3,4-tr i-O-
acetyl-r-L-fu copyr an osyl)-(1-3)]-2,6-di-O-ben zoyl-â-D-glu -
cop yr a n osid e (13′). A solution of 12 (386 mg, 0.24 mM) in
methanol (40 mL) and 1,4-dioxane (40 mL) was stirred for 40
h at room temperture in the presence of 10% Pd/C (500 mg)
under hydrogen, then filtered, and concentrated. A solution
of the residue in pyridine (30 mL) and Ac2O (15 mL) was
P h en yl O-(2,6-Di-O-ben zoyl-3,4-O-isop r op ylid en e-â-D-
ga la ctop yr a n osyl)-(1-4)-2,6-d i-O-ben zoyl-1-th io-â-D-glu -
cop yr a n osid e (6b). To a solution of 4b (1.0 g, 2.1 mM) and
pyridine (15 mL) in toluene (20 mL) was added benzoyl
chloride (2.41 g, 16.8 mM), and the mixture was stirred at 0
°C. The course of the reaction was monitored by TLC. After
the reaction, methanol was added, and the mixture was
concentrated. The residue was dissolved in AcOEt, and the
solution was successively washed with water, saturated NaH-
CO3, 1 M HCl, and water, dried with MgSO4, and then
concentrated. The preparative TLC (1:3 AcOEt-cyclohexane,
twice) of the residue gave 6b (1.44 g, 77%) as a coloress solid:
1
[R]D 14.5° (c ) 0.3, CHCl3); H NMR (CDCl3) δ 1.35, 1.63 (2s,
6H, Me2C), 3.6-3.8 (m, 2H), 4.00 (t, 1H, J ) 8.0Hz, H-3 of
Glu), 4.15-4.32 (m, 3H), 4.35-4.50 (m, 3H), 4.57 (d, 1H, J )
1.4 Hz, H-4 of Gal), 4.65 (d, 1H, J ) 8.1 Hz ,H-1 of Glu), 4.72
(17) Kameyama, A.; Ishida, H.; Kiso, M.; Hasegawa, A. J . Carbo-
hydr. Chem. 1991, 10, 549-560.
(18) Lemieux, R. U.; Driguez, H. J . Am. Chem. Soc. 1975, 97, 4069-
4075.
(19) Komba, S.; Ishida, H.; Kiso, M.; Hasegawa, A. Carbohydr. Res.
1996, 285, C1-C8.
(20) Ladish, S.; Hasegawa, A.; Li, R.; Kiso, M. Biochem. Biophys.
Res. Commun. 1994, 203, 1102-1109.

Highly Practical Synthesis of Sulfated Lewis X
J . Org. Chem., Vol. 62, No. 20, 1997 6881
stirred for 42 h at room temperature. Methanol was added,
and the mixture was concentrated. The residue was dissolved
in CHCl3 (50 mL), and the solution was successively washed
with 2 M HCl and water, dried (MgSO4) and then concentrated.
Preparative TLC (1:3 AcOEt-hexane) of the residue gave 13′
(315 mg, 90%) as an amorphous mass: [R]D -16.7° (c ) 0.15,
CHCl3); 1H NMR (CDCl3) δ 0.70-0.95 (m, 6H, 2MeCH2), 1.00-
1.50 (m, 53H), 1.32 (d, 3H, J 5,6 ) 6.4 Hz, H-6 of Fuc), 1.59,
1.64 (2s, 6H, Me2C), 1.84-2.17 (3s, 9H, 3AcO), 3.00-3.20 (m,
at room temperature. The course of the reaction was moni-
tored by TLC. Methanol was added, and the mixture was
concentrated at 25 °C to afford 17 (2.4 g, 90%) as an amorphous
mass: [R]D -2.2° (c 1.0, CHCl3); 1H NMR (CDCl3) δ 0.85-1.31
(m, 58H, 2Me, 26CH2), 1.38 (d, 3H, J ) 6.2 Hz, H-6b), 1.74-
2.35 (4s, 12H, 4AcO), 4.37 (d, 1H, J ) 7.7 Hz, H-1a), 7.09-
8.05 (m, 25H, 4Ph, pyridine). To a solution of 17 (2.4 g, 1.6
mM) in MeOH (50 mL) and THF (50 mL) was added sodium
methoxide (170 mg), and the mixture was stirred for 24 h at
room temperature and then concentrated at 25 °C. Column
chromatography (5:4:0.7, CHCl3-MeOH-H2O) of the residue
on Sephadex LH-20 gave 1 (1.42 g, 97%) as an amorphous
mass: [R]D -30° (c ) 0.8, 1:1, MeOH-CHCl3); 1H NMR
(C5D5N) δ 0.85-1.31 (m, 58H, 2Me, 26CH2), 1.54 (d, 3H, J )
6.4 Hz, H-6b), 5.06 (d, 1H, J ) 2.7 Hz, H-1b), 5.21 (dd, J )
10.1, 3.8 Hz, H-3c), 5.41 (d, 1H, J ) 7.3 Hz, H-1a), 5.48 (d,
1H, J ) 6.7 Hz, H-1c). The mass spectrum of 1 showed the
base peak at m/z 987 (M - 1 - Na).
2-Tetr a d ecylh exa d ecyl O-(4-O-Su lfo-â-D-ga la ctop yr a -
n osyl)-(1-4)-O-[(r-L-fu cop yr a n osyl)-(1-3)]-â-D-glu cop y-
r a n osid e Sod iu m sa lt (2). According to the similar proce-
dure to the compound 1, compound 2 (30 mg, 72%) was
prepared as a colorless powder: mp 194-195 °C (decomposed);
1H NMR (DMSO-d6) δ 0.7-0.9 (m, 6H), 1.06 (d, 3H, J ) 6.4
Hz), 1.1-1.6 (m, 53H), 3.1-3.3 (m, 4H), 3.3-3.8 (m, 12H), 3.96
(d, 1H, J ) 4.1 Hz), 4.0-4.3 (m, 4H), 4.29 (d, 1H, J ) 7.8 Hz),
4.42 (d, 1H, J ) 3.0 Hz), 4.45-4.65 (m, 2H), 4.66 (d, 1H, J )
5.9 Hz), 5.0-5.1 (m, 2H), 5.12 (d, 1H, J ) 3.5 Hz). The mass
spectrum of 2 showed the base peak at m/z 987 (M - 1 - Na)-.
2-Tetr a d ecylh exa d ecyl O-(3,4-O-Disu lfo-â-D-ga la ctop y-
r an osyl)-(1-4)-O-[(r-L-fu copyr an osyl)-(1-3)]-â-D-glu copy-
r a n osid e Sod iu m Sa lt (3). According to the similar proce-
dure to the compound 1, compound 3 (80 mg, 67%) was
prepared as a colorless powder: mp 201-203 °C (decomposed);
1H NMR (DMSO-d6) δ 0.7-0.9 (m, 6H), 1.06 (d, 3H, J ) 6.4
Hz), 1.1-1.6 (m, 53H), 3.1-3.3 (m, 3H), 3.3-3.9 (m, 13H), 3.99
(d, 1H, J ) 6.9 Hz), 4.0-4.3 (m, 3H), 4.4 (d, 1H, J ) 7.7 Hz),
4.4-4.7 (m, 4H), 5.0 (d, 1H, J ) 4.9 Hz), 5.1-5.2 (m, 2H). The
mass spectrum of 3 showed the base peak at m/z 1089 (M - 1
- Na)-.
1H), 3.60-3.75 (m, 1H), 3.75-3.90 (m, 1H), 4.35 (d, 1H, J 1,2
)
8.0 Hz, H-1 of Glc), 4.51 (d, 1H, J 1,2 ) 7.4 Hz, H-1 of Gal),
5.26 (dd, 1H, J 2,3 ) 8.6 Hz, H-2 of Gal), 7.20-8.30 (m, 20H,
4Ph). Anal. Calcd for C85H118O22.2H2O (1527.9): C, 66.82; H,
8.05. Found: C, 66.70; H, 7.63.
2-Tetr a d ecylh exa d ecyl O-(2,6-Di-O-ben zoyl-â-D-ga la c-
top yr a n osyl)-(1-4)-O-[(2,3,4-tr i-O-a cetyl-r-L-fu cop yr a n o-
syl)-(1-3)]-2,6-d i-O-ben zoyl-â-D-glu cop yr a n osid e (13). A
solution of 13′ (3.3 g, 2.21 mM) in 80%AcOH was stirred for 4
h at 80 °C and then concentrated. Column chromatography
(5:4 AcOEt-hexane) of the residue on silica gel gave 13 (2.81
g, 88%) as an amorphous mass: [R]D +34.8° (c ) 0.25, CHCl3);
1H NMR (CDCl3) δ 0.75-0.95 (m, 6H, 2MeCH2), 1.00-1.45 (m,
53H), 1.29 (d, 3H, J 5,6 ) 6.8 Hz, H-6 of Fuc), 1.89-2.10 (3s,
9H, 3AcO), 2.80 (d, 1H, J 3,OH ) 9.0 Hz, H- 3-OH), 3.11 (dd,
1H, J gem ) 9.6 Hz, J 1,2 ) 6.4 Hz, H-1 of lipophilic part), 3.35-
3.80 (m, 5H), 4.37 (d, 1H, J 1,2 ) 8.0 Hz, H-1 of Glc), 4.65 (d,
1H, J 1,2 ) 7.9 Hz, H-1 of Gal), 4.87(dd,1H, J ) 11.7 Hz), 5.00-
5.15 (m, 2H), 5.15-5.45 (m, 5H), 7.30-8.20 (m, 20H, 4Ph).
Anal. Calcd for C82H114O22 (1451.8): C, 67.84; H, 7.91.
Found: C, 67.47; H, 7.77.
2-Tetr a d ecylh exa d ecyl O-(4-O-Acetyl-2,6-d i-O-ben zoyl-
â-D-ga la ctop yr a n osyl)-(1-4)-O-[(2,3,4-tr i-O-a cetyl-r-L-fu -
cop yr a n osyl)-(1-3)]-2,6-d i-O-b en zoyl-â-D-glu cop yr a n o-
sid e (16). To a solution of 13 (2.5 g, 1.7 mM) in toluene (125
mL) was added triethyl orthoacetate (125 mL), and the mixture
was stirred for 1 h at room temperature. The solution was
neutralized with triethylamine and concentrated. A solution
of the residue in 80%AcOH was stirred for 40 min at room
temperature and then concentrated. Column chromatography
(2:3 AcOEt-hexane) of the residue on silica gel gave 16 (2.5g,
95%) as an amorphous mass: [R]D -39.9° (c ) 0.16, CHCl3);
1H NMR (CDCl3) δ 0.85-0.91 (m, 6H, 2MeCH2), 1.10-1.40 (m,
52H, 26CH2), 1.34 (d, 3H, J 5,6 ) 6.6 Hz, H-6 of Fuc), 1.87, 1.88,
On e-P ot, Tw o-Step Glycosyla tion . To a solution of 6b
(100 mg, 0.11 mM) and 9 (89 mg, 0.17 mM) in CHCl3 (1 mL)
was added 4 Å molecular sieves (160 mg), and the mixture
was stirred for 2 h at room temperature and then cooled to
-20 °C. NIS (57 mg) and TfOH (8 µL) were added to the
mixture, and this was stirred for 30 min at -20 °C. To the
reaction mixture was added a solution of 11 (100 mg, 0.23 mM)
in CHCl3 (1 mL), NIS (50 mg), and TfOH (5 µL). The reaction
mixture was stirred for 30 min at -20 °C. The course of the
reaction was monitored by TLC. The precipitate was filtered
off and the filtrate was successively washed with aqueous
Na2S2O3, aqueous NaHCO3, and water, dried with MgSO4, and
concentrated. Preparative TLC (AcOEt:hexane ) 1:3) of the
residue gave 12 (147 mg, 80%) as an amorphous mass.
2.11, 2.25 (4s, 12H, 4AcO), 3.11 (dd, 1H, J gem ) 9.5 Hz, J 1,2
)
6.4 Hz, H-1 of lipophilic part), 3.6-3.8 (m, 2H), 3.85-3.91 (m,
1H, H-3 of Gal), 4.38 (d, 1H, J 1,2 ) 8.0 Hz, H-1 of Glc), 4.67 (d,
1H, J 1,2 ) 8.2 Hz, H-1 of Gal), 5.06 (dd, 1H, J 2,3 ) 10.8 Hz, J 3,4
) 4.0 Hz, H-3 of Fuc), 5.40 (d, 1H, J 3,4 ) 3.6 Hz, H-4 of Gal),
5.47 (d, 1H, J 1,2 ) 2.8 Hz, H-1 of Fuc), 7.30-8.20 (m, 20H,
4Ph). Anal. Calcd for C84H116O23 (1493.8): C, 67.54; H, 7.83.
Found: C, 67.54; H, 7.72.
2-Tetr a d ecylh exa d ecyl O-(3-O-Su lfo-â-D-ga la ctop yr a -
n osyl)-(1-4)-O-[(r-L-fu cop yr a n osyl)-(1-3)]-â-D-glu cop y-
r a n osid e Sod iu m Sa lt (1). To a solution of 16 (2.41 g, 1.6
mM) in DMF (25 mL) was added sulfur trioxide-pyridine
complex (2.6 g, 16 mM), and the mixture was stirred for 1 h
J O970076M