Synthesis of Sialo-oligosaccharides and Their Ceramide Derivatives

Chapter 11

Synthesis of Sialo-oligosaccharides and Their Ceramide Derivatives as Tools for Elucidation of Biologic Functions of Gangliosides

Downloaded by COLUMBIA UNIV on August 19, 2012 | http://pubs.acs.org Publication Date: May 5, 1994 | doi: 10.1021/bk-1994-0560.ch011

Akira Hasegawa Department of Applied Bioorganic Chemistry, Gifu University, Gifu 501-11, Japan

A facile, regio- and α-stereoselective glycoside synthesis of sialic acids by use of the methyl or phenyl 2-thioglycoside of sialic acids as the glycosyl donor and the suitably protected galactose and lactose acceptors in acetonitrile under kinetically controlled conditions is described. This procedure is effectively applied to the systematic synthesis of sialyloligosaccharides such as the sialyl Lewis X epitope and its analogs, and their ceramide derivatives. These compounds can be used to elucidate the structural features of sialyl oligosaccharides necessary for selectin recognition.

Sialic acid-containing oligosaccharides are the important constituents of gangliosides and glycoproteins. Biologically, these membrane components are considered to be responsible for many primary physiological activities (7-5) and the sialyl oligosac charide moieties of these glycoconjugates are exposed as ligands to the external environment, capable of expressing biological functions which are harmonious to these chemical structures. An approach towards the systematic understanding of structurefunction relationships of the sialo-oligosaccharides necessitates efficient regio- and stereoselective synthetic routes, affording various sialo-oligosaccharides, their deriva tives and analogs. The focal point in the synthesis of sialo-oligosaccharides has been the stere oselective α-glycosylation of sialic acid with various sugar residues. Recently, we have developed (6-9) a facile regio- and α-stereoselective glycosylation of sialic acids using the 2-thioglycosides of sialic acids as the glycosyl donors and the suitably protected galactose and lactose acceptors with dimethyl(methylthio)sulfonium triflate (DMTST) (10) or N-iodosuccinimide (NIS) (11-12) as the glycosyl promoter in acetonitrile under kinetically controlled conditions. The α-glycosides of sialic acids thus obtained have been effectively employed as the building blocks for the systematic synthesis of sialo-glycoconjugates. In the first part of this article we describe the efficient method for the α-glycoside synthesis of sialic acids. A systematic synthesis of the sialyl Le oligosaccharide, various types of analogs, and their ceramide derivatives, which are useful for determining the structural requirements necessary for selectin recognition is then described. x

0097-6156/94/0560-0184$08.00/0 © 1994 American Chemical Society

In Synthetic Oligosaccharides; Ková, P.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994.

11. HASEGAWA

Sialo-oligosaccharides and Their Ceramide Derivatives 185


Regio- and α-Stereoselective α-Glycoside Synthesis of Sialic Acids Sialic acids are as constituents of glycoproteins and gangliosides of cell membranes, and they play important roles in many biological processes. The naturally occurring sialo compounds contain sialic acids with an α-glycosidic linkage, except for CMP-Nacetylneuraminic acid. Kuhn et al (13) were the first to attempt the glycosylation of sialic acid with sugar derivatives, employing the 2-chloro derivative of N-acetylneuraminic acid (Neu5Ac) as the glycosyl donor. With the 2-halo-derivatives of Neu5Ac, the yield and stereos electivity of the glycosides are generally poor, especially of those with the secondary hydroxyl groups of sugar derivatives. Particularly annoying is the competitive elim ination due to the deoxy center at position 3, resulting of the 2,3-dehydro derivative. The bottleneck in these reactions has been controlling the formation of this elimination product by the selection of suitably designed glycosyl donors and glycosyl promoters. In addition, achieving α-glycosides in high yield is very difficult because the βglycosides are thermodynamically favored. Recently, several new efforts have been developed towards obtaining mainly aglycosides, using the 2-halo-3-substituted Neu5Ac derivatives (14-15), Neu5Ac phos phites (16-17), 5-glycosyl xanthates (18-19) of Neu5Ac, and the 2-thioglycosides of sialic acids (6-9). A facile sialylation of suitably protected sugar derivatives with thioglycosides derivatives of sialic acids by use of thiophilic promoters will be described herein. With the wide utility of thioglycosides in oligosaccharide synthesis, preliminary attempts (6) using the methyl a-2-thioglycoside (20) or the 1:1 anomeric mixture (7) of Neu5Ac as a suitable glycosyl donor and DMTST [dimethyl(methylthio)sulfonium triflate] as a promoter and various alcohols as the acceptors, indicated that the reactions conducted in acetonitrile under kinetically controlled conditions afforded predominantly α-gly cosides in high yields. This method was successfully extended to the synthesis of sialyl a(2-»3)- and sialyl a(2->6)-sugar derivatives in high yields (50-70%) which is, perhaps, the best among those reported so far. Iodonium-ion-promoted glycosylations (11-12) are also attractive for oligosaccharide syntheses. We have examined its application to the sialylation involving the 2-thioglycoside of sialic acids and reported (9) the comparative reactivities of DMTST and NIS/TfOH in acetonitrile or dichloromethane, with the objective of obtaining predominant α-glycoside (Table 1; Figure 1). Notably, with DMTST in acetonitrile, secondary hydroxyls were glyco sylated to give exclusively the a-configuration (40-50%), while an anomeric mixture (α:β -4:1; 65%~90%) was formed with primary hydroxyls. With NIS/TfOH in ace tonitrile, on the other hand, even hindered primary and unreactive secondary hydroxyls were glycosylated in high yields (-70%), but the increased amount of the β-glycoside was formed in some cases. Further, the reactions in dichloromethane with either DMTST or NIS/TfOH showed poor stereoselectivity. Based on the aforementioned results, a reasonable reaction mechanism can be postulated as follows (Figure 2). A less reactive acceptor nucleophile and stable donor anomeric-intermediate (d) are the two probable factors leading to the formation of aglycoside of sialic acids. On the other hand, the reactive alcohol can attack other intermediates along with (d), consequently increasing the amounts of the β-glycosides are formed. In addition, using dichloromethane, the nucleophile reacts with the intermediates (a), (b) and (c) to give an anomeric mixture nonstereoselectively. General glycosylation procedure: 2-(Trimethylsilyl)ethyl 0-(methyl 5acetamido-4J,8,9-tetra-0-acetyl-3,5-dideoxy-D-g\ycçTo-a-O^^ nonulopyranosylonate)-(2 ->3)-6-0-benzoyl-$-D-galactopyranoside (10). (a) DMTST-promoted glycosylation by use of the methyl 2thioglycoside (la) of Neu5Ac. To a solution of l a (2.7 g, 5.2 mmol) and 2


186

SYNTHETIC OLIGOSACCHARIDES

AcOÔAc COOMe AcO R ' S ^ AcHN ° laR = Me lbR = SPh

OH

1

3


OBn

OAc

OR4

NHAc 6 R = Bz, R = OH, R = R H 7R = Bn,R = R = H,R = OH

3

1

2

3

^ôs

R

A c

q

2

1

3

2

4

4

3

3

3

2

Η

ό ÔBz

wn

AcO OAc L /

"YÔBz

Ar(P~7^n-^

COOMe O

H

OSE 1 0

13R = Bn H

°

S

A c O ^ O ^ R ^ ^ ° A c H N ^ - T ^ y COOMe OH AcO 12 R = Bz 14 R = Bn AcOOAc C

0

0

M

H

AcO E

^ ^ JTSIA,

^

° OBn

° ^ COOMe

{

^ O

B

n

15

e

v

AcO * AS

A C H N

r

R

^"

2

AcHN^^TW

~ f \ ^ ° \

COOMe

1

NHAc

2

3

17R = Bz,R = OH,R = H L

2

V

1 9R

U R I Bn! R 1 HTR = OH ~ _ AcO OAc A

AcO

COOMe

O

R

n

uAÔBn HO 20 0

AcOOAc AcO

B

COOMe

O

R

OH

HO OBz

R

H

R

=

' * = « ' °

H

HO ÔBn I \

n

OBn

n

'

= B N

AcOrTÔÂ AcHN^-T^W COOMe AcO 21 O

B

.OBn N

°

BN

.OBz, OBz

Bn = benzyl SE = 2-(trimethylsilyl)ethyl

22 Figure 1

Regio- and α-Stereoselective Glycoside Synthesis of Sialic Acids


11. HASEGAWA

Sialo-oligosaccharides and Their Ceramide Derivatives

Table I. DMTST*- and NIS-TfOH**-Promoted Glycosylation Acceptor

Donor

Product

Promoter Solvent

Yield*** {%)


α

β

2 2 2

la la lb

DMTST NIS NIS

CH CN CH CN CH CN

10 10 10

52 61 70

0 0 0

3 3 3

la la la

DMTST NIS NIS

CH CN CH CN CH2CI2

11 11 11,12

70 59 49

0 0 25

4 4 4

la la la

DMTST NIS NIS

CH CN CH CN CH2CI2

13,14 13,14 13,14

50 51 43

15 26 45

5

lb

NIS

CH CN

15

70

0

6 7

la la

DMTST DMTST

CH CN CH CN 3

16,17 18,19

71 63

20 14

8 8

la la

DMTST NIS

CH CN CH CN

20,21 20,21

30 59

8 10

9 9

la lb

DMTST NIS

CH CN CH CN

22 22

47 55

0 0

3

3

3

3

3

3 3

3

3

3

3

3

3

* Reactions were performed at - 15°C ** Reactions were performed at -35 ~ -40°C *** Isolated yield

+

DMTST !OOMe. s

AcO AcHN

R

Ο

f, ji^S -SMe ^ O y ^ OA' YMOAC

1

OAc

1 R = Me or Ph

CH C +···

3

Ν

CF S0 -

Q

(a|

COOMe AcHN _ T

3

3

OAc

'el |b| >COOMe CH,

ι α - glycoside Figure 2

β - glycoside

The Reaction Mechanism Suggested for α - P r e d o m i n a n t Glycoside Formation of Neu5Ac


187

188


(1.0 g, 2.6 mmol) in dry acetonitrile (20 mL) were added powdered molecular sieves3Â (MS-3Â; 3 g), and the suspension was stirred for 5 h at room temperature, then cooled to -40°C. To the cooled suspension DMTST (6.53 g; 62% DMTST by weight, 3.0 equiv. relative to the donor) and MS-3Â were added, and the mixture was stirred for 17 h at -15°C. Methanol (1 mL) was added to the mixture, and it was neutralized with triethylamine. The solids were filtered off and washed thoroughly with CH2CI2, and the combined filtrate and washings were concentrated. The residue was dissolved in CH2CI2 and the solution was successively washed with M Na2CC>3 and water, dried (Na2S04), and evaporated. Column chromatography (1:1 EtOAc-hexane) of the residue on silica gel gave 10 (1.16 g, 52%) as an amorphous mass, [CX]D -6.0° (c 2.0


CHCI3).

(b) NIS-TfOH-promoted glycosylation by use of the methyl 2thioglycoside (la) of Neu5Ac. To a solution of l a (1.67 2, 3.2 mmol) and 2 (730 mg, 1.9 mmol) in dry acetonitrile (15 mL) powdered MS-3A (2.3 g) were added. The mixture was stirred for 5 h at room temperature and then cooled to -40°C. To the cooled mixture were added NIS (1.44 g, 6.4 mmol) and TfOH (96 mg, 0.64 mmol), and the mixture was stirred for 2 h at -40°C. A similar work-up as described above gave 10 (995 mg, 61%). (c) NIS-TfOH-promoted glycosylation by use of the phenyl 2thioglycoside of Neu5Ac To a solution of l b (10.7 g, 18.4 mmol) and 2 (3.84 g, 10 mmol) in dry acetonitrile (50 mL) and CH2CI2 (5 mL) were added powdered MS-3À (20 g), and the mixture was stirred overnight at room temperature, then cooled to -40°C. To the cooled mixture were added NIS (8.28 g, 36.8 mmol) and TfOH (540 mg, 3.6 mmol), and the mixture was stirred for 2.5 h at -35°C. A similar work-up as described above gave 10 (6.0 g, 70%). 2-(Trimethylsilyl)ethyl 0-(methyl5-acetamido-4J,8,9-tetra-0-ace D-glycero-a-D-galacto-2-«ortw/0py^^

noside (11). To a solution of l a (2.7 g, 5.2 mmol) and 3 (1.0 g, 2.6 mmol) in dry acetonitrile (20 mL) were added powdered MS-3À (3 g), and the mixture was stirred for 6 h at room temperature, then cooled to -15°C. A mixture (6.53 g, 62% DMTST by weight) of DMTST and MS-3Â was added to the mixture, and this was stirred for 17 h at -15°C. Processing as described for the synthesis of 10, and chromatography (silica gel) using 1:1 EtOAc-hexane as eluent afforded 11 (1.56 g, 70%) as an amorphous mass, [α]ο -6.4° (c 0.4, CHCI3). Synthesis of sialyl Lewis X and its analogs x

Sialyl Lewis X (sLe ) was first isolated (21) from the human kidney and found to be widespread as a tumor-associated ganglioside antigen. Recently, it has been demon strated (22-32) that the selectin family, such as E-selectin (endothelial leukocyte ad hesion molecule-1, ELAM-1), P-selectin (granule membrane protein, GMP-140), and L-selectin (leukocyte adhesion molecule-1), recognizes the sLe determinant, aNeu5Ac-(2-»3)-p-D-Gal-(l->4)-[a-L-Fuc-(l-^3)]-p-GlcNAc. This sequence is found as the terminal carbohydrate structure in both cell membrane glycolipids and glyco proteins. In view of these new findings, it is of interest to elucidate the structural requirements for the expression of such biological activities which are related to cellcell adhesion, tumor-metastasis, inflammation, and thrombosis. Synthesis of Sialyl L e and its Position Isomer. Sialyl Le (33) and its sialyl a(2->6) positional isomer (34) with regard to the substitution of the Gal residue by Neu5Ac were synthesized according to our established method. As shown in Figure 3, the trisaccharide acceptor 25 (35) was first coupled with 23 or 24 in the presence of DMTST in benzene to give the desired a-tetrasaccharides (26) in 86~95% yields. Reductiveringopening of the benzylidene acetal in 26 with sodium cyanoborohydridehydrogen chloride (36) gave 27, which, on glycosylation with 28, afforded the x

x

x


HASEGAWA


1

NHAc

23R = Bn 24 R = Ac OBn , Y ÔBn

ÔRi


OBn ÔBn

25

1

2

OBn

AcO OAc

2

O

O

M

e

f AcO OAc coOH

3

26 R , R = benzylidene, R = Bn or Ac 27 R = Bn, R = H, R = Bn or Ac 1

C

3

29

AcO

B z

o OBz J Zr2^0R 4 OR M C

3

c

B

Z

3

NHAc OR OR 30 R = OSE, R = H, R = Bn, R = Bn or Ac 31 i OSE, R = H, R = R = Ac 31 R , R = H, OH, R = R = Ac 32 R = H, R = OC(=NH)CCl , R = R = Ac

3

1

4

R

°

2

3

2

0

R

4

3

4

=

1

2

3

1

4

2

3

4

3

AcOÔAc

on*

COOMe

x°Ac y

?

UAC

OBz

UUUMe

A

c

x

O

A

9-

OAc OAc

c

Y ^ÂC

Bz U

i

A cl A

OAc

ÔBz^ „ jTÔBz AcÔ

JI UOAc

NHAc NHAc

OAc OAc OAc 34 R = N 35 R = NH 36 R = NHCOC H c

O A c

2

17

HO^PH H

O

COOH

OH O

H

H(

L£

-benzyl-L-fucose moiety was used as acceptor, the yield of 30 was increased to 70%. Hydrogenolytic removal of the benzyl groups and subsequent acetylation afforded 31 (81%). Selective removal of the 2-(trimethylsilyl)ethyl group in 31 using trifluoroacetic acid (37), and subsequent treatment (38) with CCI3CN in the presence of l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) gave the ct-imidate 33 (91%). The final glycosylation of (25,3/?,4£)-2-azido-3-0-benzoyl-4-octadecene-l,3-diol (39) with 33 thus obtained in the presence of boron trifluoride etherate, afforded only the expected β-glycoside 34 (56%), which was transformed via selective reduction of the azido group, coupling of the amine 35 with octadecanoic acid, 0-deacylation, and saponification of the methyl ester group, into the title sialyl Le ganglioside 37 in high yield. Similarly, by the coupling of 27 with sialyl a(2->6)-galactose donor 29 (41) and subsequent reactions as described for the synthesis of 37, a positional isomer (38) of sialyl Le , was synthesized. Sialyl Le oligosaccharide (39) (69%) was also synthesizedfrom32 via 0-(tetrahydropyran-2-yl)ation, (9-deacylation, saponification of the methyl ester group, and hydrolysis of the tetrahydropyranyl group. 2-(Trimethylsilyl)ethyl 0-(methyl 5-acetamido-4,7\8 9-tetra-0-acetyl-3 5-dideoxyx


x

x

}

}

D-glycero-a-D-galacto-2-tt0A2w/0/?yra

galactopyranosyl)-(l^)-0-[3,4-di-0-acetyl-2-0-benzy^ 0-(2-acetamido-6-0-benzyl-2-deoxy-^-\y-glucopym benzyl-$-O-galactopyranosyl)-(l^)-2,3,6-tri-0-ben^ (Protected sialyl Le oligosaccharide) (30) To a solution of 27 (1.25 g, 0.78 mmol) and 28 (1.1 g, 1.1 mmol) in dry CH2CI2 were added powdered MS-4Â (5 g), and the mixture was stirred overnight at room temperature, then cooled to 0°C. A mixture (1.14 g; 50% DMTST by weight) of DMTST and MS-4Â (500 mg) was added, and the stirring was continued for 48 h at 0°C. Methanol (1 mL) and ΕίβΝ (0.5 mL) were added to the mixture, and the solids were filtered off and washed with CH2CI2. The filtrate and washings were combined and washed with water, dried (Na2SC>4), and concentrated. Column chromatography (50:1 CHCl3-MeOH) of the residue on silica gel gave 30 (1.4 g, 70%) as an amorphous mass, [a] -23.2° (c 1.2, CHC1). Sialyl Le oligosaccharide (39) To a solution of 32 (150 mg, 0.07 mmol) in pdioxane (3 mL) were added 3,4-dihydro-2//-pyran (0.5 mL) and p-toluenesulfonic acid monohydrate (20 mg), and the mixture was stirred for 5 h at room temperature, then neutralized with Amberlite IR-410 (HO ) resin and concentrated. To a solution of the residue in MeOH (5 mL) was added NaOCH3 (30 mg), and the mixture was stirred for 2 days at room temperature, water (0.5 mL) was added to the mixture, and it was stirred for 16 h at room temperature, and neutralized with Amberlite IR-120 (H ) resin, then concentrated. A solution of the residue in aq. 60% AcOH (10 mL) was heated for 2 h at 45°C and concentrated. Column chromatography (1:1 MeOH-H20) of the residue on Sephadex LH-20 (50 g) gave 39 (60 mg, 69%) as an amorphous mass, [cc] -20.3° (c 0.26, H 0 ; equil.). x

D

3

x

-

+

D

2

Synthesis of the deoxy-fucose-containing sialyl L e

x

gangliosides

x

The synthesis of the sialyl Le oligosaccharides containing 2-, 3-, and 4-deoxy-fucose moieties is described next. These were utilized to clarify the structural requrirements on the fucose moiety necessary for selectin recognition. For the synthesis of the target sLe analogs, we employed the methyl 1-thioglycosides 40-42 of the appropriate deoxy-L-fucose derivatives as the glycosyl donors (Hasegawa, Α.; Ando, T.; Kato, M.; Ishida, H.; Kiso, M. Carbohydr. Res., in press) and 2-(trimethylsilyl)ethyl (9-(2acemmido-4,6-0-benzylidene-2-deoxy-p-D-glucopyranosyl)-(1^4)-2,4,6-tri-0-benzylβ-D-galactopyranoside (42) as a suitably protected glycosyl acceptor (Figure 4). x


HASEGAWA


OR* OBn MeTô-V^R R

2

J IT R

S

NHAc

OBn

3

1

2


R R 40 H.SMe 41 H SMe 42 H SMe

R

3

H OBn OBn

R

R

1

R

3

OSE H OSE H H OC(=NH)CCl OSE H OSE H OSE H H OC(=NH)CCl OSE H OSE H OSE H H OC(=NH)CCl OSE H

49 50 51 52 53 54 55 56 57 58 59 60

3

3

3

R»0,OR»

R

' °

43 44 45 46 47 48

OBz OBz H H OBn OBn

R

5

R

OBz OBz OBz OH H H H H OBn OAc OAc OH

OBz OBz OBz OH OBn OAc OAc OH H H H H

OBz OBn H

2

COOR'

R

R

Bn Ac Ac H Bn Ac Ac H Bn Ac Ac H

H H H H OBn OAc OAc OH OBn OAc OAc OH

OR'

MefR R R

4

-OR

I

R*o\>R'

2

R

H H OBn OBn OBn OBn

R

OBz H OBn

1

R

5

4

3

OR*

R

7

6

3

R

R

8

R

R

Bz Bz Bz H Bz Bz Bz H Bz Bz Bz H

Me Me Me H Me Me Me H Me Me Me H

4

R

5

benzylidene H Bn benzylidene H Bn benzylidene H Bn

OBz OBz OBn OBn H H

9

Ac Ac Ac H Ac Ac Ac H Ac Ac Ac H

,

N H A c R

°

3

OR*

5

6

R

l

2

61 Bz N 62 NHCOC H Η 63 N Bz 64 NHCOC H Η 65 Bz N 66 NHCOCnH^ Η 3

l7

35

17

35

3

3

Figure 4

3

4

R

R

Ac Η Ac Η Ac Η

Η Η OAc OH OAc OH

R

5

OBz OH Η Η OAc OH

R

6

OBz OH OAc OH Η Η

R

7

Me H Me H Me H

R

8

Ac H Ac H Ac H

Synthesis of the Deoxy-Fucose-Containing sLe

x

Gangliosides



192


Glycosylation of the acceptor with 40-42 in benzene for 10 h at 5-10°C, using DMTST as a promoter, gave exclusively the α-glycosides 43 (86%), 45 (82%), and 47 (57%), respectively. These were converted by reductive ring-opening of the benzylidene acetal with sodium cyanoborohydride, into the glycosyl acceptors 44 (97%), 46 (80%), and 48 (87%). DMTST-promoted glycosylation of 44,46 and 48 with the sialyl a(2-»3)-Gal donor 28 afforded the desired pentasaccharides 49,53 and 57, which were converted via reductive removal of the benzyl groups, O-acetylation, selective removal of the 2-(trimethylsilyl)ethyl group, and subsequent imidate formation, into the corresponding a-trichloroacetimidates 51,55, and 59 respectively in good yields. Glycosylation of (25,3/?,4£)-2-azido-3-(9-benzoyl-4-octadecene-l,3diol with 51, 55, or 59 thus obtained afforded only the expected β-glycosides 61 (85%), 63 (64%), and 65 (60%) respectively, which were transformed in good yields, via selective reduction of the azido group, coupling with octadecanoic acid, Odeacetylation, and de-esterification, into the target gangliosides 62 (55%), 64 (97%), and 66 (82%). The sialyl Le oligosaccharide analogs 52,56, and 60 were obtained in good yields, by O-deacylation of 50,54, or 58, and subsequent hydrolysis of the methyl ester group. x

Synthesis of the chemically modified sialic acid-containing ganglioside analogs

sialyl L e

x

x

The synthesis of sLe ganglioside analogs containing the C7-Neu5Ac, Cs-Neu5Ac and 8-epi-Neu5Ac, to explore the structural requirements of the sialic acid moiety for selectin recognition, was completed as follows. Methyl 0-(methyl 5-acetamido-4,7-di--2-heptulopyranosylonate)-(2->3)-, methyl 0-(methyl 5-acetamido-4,7,8-tri-0-acetyl-3,5dideoxy-a-D-ga/3)-2,4,6-tri-(9-benzoyl-l-thio-p-D-galactopyranosides (77, 81, and 85) were selected as the glycosyl donors, and 2-(trimethylsilyl)ethyl 0-(2,3,4-tri-0-benzyla-L-fucopyranosyl)-(l->3)-0-(2-acetamido-6-6)-benzyl-2-deoxy-p-D-glucopyranosyl)(l-^3)-2,4,6-tri-0-benzyl-p-D-galactopyranoside (42) as the glycosyl acceptor (Figure 5). Compounds 77, 81, and 85 were prepared by glycosylation of 2 with the 2thioglycosides 70, 72, and 73 (43), using NIS-TfOH in acetonitrile for 2 h at -35°C, followed by O-benzoylation, selective transformation of the 2-(trimethylsilyl)ethyl group to acetyl by treatment (37) with boron trifluoride etherate, and introduction (7) of the methylthio group with methylthio(trimethyl)silane. Glycosylation of the trisaccharide acceptor with these donors (1.45 equiv. with respect to the acceptor), in dichloromethane for 48 h at 5°C in the presence of DMTST, yielded the expected β-glycosides, 86 (53%), 90 (53%), and 94 (47%), respectively. Catalytic hydrogenolysis (10% Pd-C) in ethanol-acetic acid for 3 days at 45°C of the benzyl groups in 86, 90, or 94, and subsequent O-acetylation gave the per-0-acyl derivatives, 87 (85%), 91 (87%), and 95 (83%) after column chromatography. Compounds 87, 91, and 95 were converted into the corresponding a-trichloroace timidates, 89, 93, and 97, according to the method described for the synthesis of 33, and these, when coupled with the azido-sphingosine derivative, gave the required βglycosides, 98 (68%), 101 (43%), and 104 (46%). Finally, these were transformed via selective reduction of the azido group, condensation with octadecanoic acid, 0deacylation and de-esterification into the target sLe ganglioside analogs 100,103, and 106 in good yields, according to our established method (44). x


11. HASEGAWA


R

COOMe OSE

AcHN AcO

AcHN AcO R ,R l

67 R = Χ 68 R = Y

69 70 71 72

1

ME


A

Γ

«=°

74 75 76 77 78 79 80 81 82 83 84 85

1

OSE OSE OAc SMe OSE OSE OAc SMe OSE OSE OAc SMe

3

R

2

AIT^

R

OH OBz OBz OBz OH OBz OBz OBz OH OBz OBz OBz

R

OAc, COOMe SPh, COOMe OAc, COOMe SPh, COOMe

X X X X

R

1

Y

1

Y

1

B Z 0

OBz

^0B

. R

A

V

3

NHAC ( / R ' ^

J

Z

=Z 73

3

1

1 1

1

1

Y

1

Y

1

Y

1

R OSE OSE

86 87 88 89 90 91 92 93 94 95 96 97

1

Y

z z z z

X X

1

COOMe COOMe

1 1 l 1

44

A C H R>

R

2

£L

ΛθΒ*

κ

R

COOMe

1

J:°°

.3

1

R

3

3

R OBn OAc OAc OAc OBn OAc OAc OAc OBn OAc OAc OAc

2

R H H

H, OH H OC(=NH)CCl OSE H OSE H H, OH H OC(=NH)CCl OSE H OSE H H, OH H OC(=NH)CCl

3

3

3

COOR R .R L ^ R R2 N 2 ^ O ^ ^ O ^ 5 ^ 0 ^ ^ 0 I / V £V J NHAc R> Me-TÔ-V , 1

R X X X X

4

1

1

1

1

Y

1

Y

1

Y

1

Y

1

z z z z

1 1

1 1

3

3

C

^

ψ * * R 1

R OBz OBz OH OBz OBz OH OBz OBz OH

98 99 100 101 102 103 104 105 106

5

R

N NHCOC H35 NHCOC H35 N NHCOC H3s NHCOC H3s N NHCOCpHa 3

17

17

3

l7

17

3

NHCOCH35

5

R X X X

4

R Me Me H Me Me H Me Me H

3

2

R OAc OAc OH OAc OAc OH OAc OAc OH

17

HCOAc £H OAC 2

2'}= HCOAc AcOCH

X = CH OH: 2

2

1

1

2

Y

1

Y

1

Y

2

z z z

1 1 2

Y

2

CH OH 2

CH OAc 2

Figure 5

Synthesis of the Modified Neu5Ac-Containing sLe

HCOH HOCH CH OH 2

x

Ganglioside Analogs


193

194


1

R

H

H

108

H

ClAc

109

Ac H

R


107

2

Ζ = benzyloxycarbonyi ClAc = chloroacetyl

R

2

° > 0 R

2

COORS

O R

OR

4

. Λ

Ro 2

R

4

I

ÔR

Q

benzylidene H

3 R

Bn

I

OR

OR R

110 111

2

3

3 OR> 0

Sialyl Le* analog 1

R

3

R

4

112

Ζ

Bz

Me

113

Me Ac

Bz

Me

114

Me H

H

H

Ac

Bn

a

Sialyl Le analog R

4

R

115

Ζ

Ac

Bz benzylidene Me

116

Ζ

Ac

Bz

Figure 6

H

1

2

R

3

R

4

R

S

Bz

Bn Me

118

Me Ac

Bz

H

Me

119

Me Η

Η

Η

Η

Bn Me

Ζ

R

Ac

117

a

Synthesis of 1-Deoxynojirimycin-Containing sLe and sLe Ganglioside Analogs


x

11. HASEGAWA

Sialo-oligosacchandes and Their Ceramide Derivatives 195 a

Synthesis of 1-deoxynojirimycin-containing sLe and sLe

x

analogs.

Synthesis (Kiso, M.; Furui, H.; Ando, K.; Hasegawa, A. / . Carbohydr. Chem. in press) of sLe and sLe analogs, in which N-acetylglucosamine residue in sLe and sLe oligosaccharide epitopes is replaced by 1-deoxynojirimycin derivative, is described (Figure 6). Glycosylation of 109 (obtained from 4,6-O-benzylidene-iVbenzyloxycarbonyl-l,5-dideoxy-l,5-imino-D-glucitol (45) (107) via selective 3-0chloroacetylation, 2-O-acetylation of 108, and dechloroacetylation with aq. pyridine) with the fucose donor 23 in the presence of DMTST in benzene for 2 h gave 110 (92%) as an amorphous mass. Reductivering-openingof the benzylidene acetal in 110 gave the disaccharide glycosyl acceptor 111 (81%). The glycosylation of 111 with the sialyl galactose donor 28 using NIS-TfOH in dichloromethane gave the desired tetrasaccharide 112 (61%), which was transformed via catalytic hydrogenolysis of the benzyl and benzyloxycarbonyi groups using Pd-black in 1:1 methanol-acetic acid, 0-deacylation and saponification of the methyl ester group, into the sLe analog 114 in good yield. On the other hand, glycosylation of 109 with the sialyl a(2->3)Gal donor 28 using NIS-TfOH as described for 112 gave 115 (90%). Reductive ring opening of the benzylidene group in 115 gave 116 which was then coupled with 23 in the presence of DMTST (as described for 110) to afford the desired tetrasaccharide 117 (89%). Compound 117 was easily transformed via hydrogenolysis of the benzyl and benzyloxycarbonyi groups, O-deacylation, and deesterification, into the target sLe analog 119, quantitatively. As described in this article, the facile stereo-controlled glycosylations of sialic acids with the suitably protected sugar residues are now feasible using either DMTST or NIS-TfOH in acetonitrile under kinetically controlled conditions. By using this procedure, a variety of sialyl oligosaccharides and their ceramide derivatives (ganglioside) and analogs have systematically been synthesized. These molecules will be used to define the structural requirements necessary for selectin recognition. a

x

a


x

x

a

Acknowledgments This work was supported in part by a Grant-in-Aid (No. 04250102 and No. 03660132) for Scientific Research on Priority Areas from the Ministry of Education, Science and Culture of Japan. The author would like to express his gratitude to various colleagues cited in the references.

Literature Cited 1. Wiegandt, H. In Glycolipids; Wiegandt, H. Ed.; New Comprehensive Biochemistry 10; Elsevier: Amsterdam, New York, Oxford, 1985; pp 199-260. 2. Reutter, W., Köttgen, E., Bauer, C., Gerok, W. In Biological Significance of Sialic Acids; Schauer, R., Ed.; Cell Biology Monographs 10; Springer-Verlag: Wien, New York, 1983; pp 263-305. 3. Furukawa, K., Kobata, Α., in Cell Surface Carbohydrates-Their Involvement in Cell Adhesion; Ogura, H., Hasegawa, Α., Suami, T., Eds.; Carbohydrates -Synthetic methods and Applications in Medicinal Chemistry; Kodansha-VCH: Tokyo, Weinheim, New York, Cambridge, Basel, 1992; pp 369-384. 4. Hakomori, S. Sci. Am. 1986, 254, pp 32. 5. Tsuji, S.; Yamakawa, T.; Tanaka, M.; Nagai, Y. J. Neurochem. 1988, 50, pp 414.



196


6. Murase, T.; Ishida, H.; Kiso, M.; Hasegawa, A. Carbohydr. Res. 1988, 184, pp c1. 7. Hasegawa, A; Ohki, H.; Nagahama, T.; Ishida, H.; Kiso, M. Carbohydr. Res. 1991, 212, pp 277. 8. Hasegawa, A; Ogawa, M.; Ishida, H.; Kiso, M. J. Carbohydr. Chem. 1990, 9, pp 393. 9. Hasegawa, Α.; Nagahama, T.; Ohki, H.; Hotta, K.; Ishida, H.; Kiso, M. J. Carbohydr. Chem. 1991, 10, pp 493. 10. Fugedi, P.; Garegg, P. J. Carbohydr. Res. 1986, 184, pp c1. 11. Konradsson, P.; Udodong, U. S.; Fraser-Reid, B. Tetrahedron Lett. 1990, 31, pp 4313. 12. Veeneman, G. H.; van Leeuwen, S. H.; van Boom, J. H. Tetrahedron Lett. 1990, 31, pp 1331. 13. Kuhn, R.; Lutz, P.; MacDonald, D. L. Chem. Ber. 1966, 99, pp 611. 14. Ogawa, T.; Itoh, Y. Tetrahedron Lett. 1987, 28, pp 6221. 15. Kondo, T.; Abe, H.; Goto, T. Chem. Lett. 1988, pp 1657. 16. Martin, T. J.; Schmidt, R. R. Tetrahedron Lett. 1992, 33, pp 6123. 17. Sim, M. M.; Kondo, H.; Wong, C. H. J. Am. Chem. Soc. 1993, 115, pp 2260. 18. Lönn, H.; Stenvall, K. Tetrahedron Lett. 1992, 33, pp 115. 19. Marra, Α.; Sinaÿ, P. Carbohydr. Res. 1990, 195, pp 303. 20. Hasegawa, Α.; Nakamura, J.; Kiso, M. J. Carbohydr. Chem. 1986, 5, pp 11. 21. Pauvala, H. J. Biol. Chem. 1976, 251, pp 7517. 22. Phillips, M. L.; Nudelman, E.; Gaeta, F. C. Α.; Perez, M.; Singhal, A. K.; Hakomori, S.; Paulson, J. C. Science 1990, 25, pp 1130. 23. Walz, G.; Aruffo, Α.; Kolanus, W.; Bevilacqua, M.; Seed, B. Science 1990, 250, pp 1132. 24. Tyrell, D.; James, P.; Rao, N.; Foxall, C.; Abbas, S.; Dasgupta, F.; Nashed, M.; Hasegawa, Α.; Kiso, M.; Asa, D.; Kidd, J.; Brandley, Β. K. Proc. Natl. Acad. Sci. USA 1991, 88, pp 10372. 25. Polly, M. J.; Phillips, M. L.; Wayner, E.; Nudelman, E; Singhal, A. K.; Hakomori, S.; Paulson, J. C. Proc. Natl. Acad. Sci. USA 1991, 88, pp 6224. 26. Tanaka, Α.; Ohmori, K.; Takahashi, N.; Tsuyuoka, K.; Yago, Α.; Hasegawa, Α.; Kannagi, R. Biochem. Biophys. Res. Commun. 1991, 179, pp 713. 27. Kotovuori, P.; Tontti, E.; Pigott, R.; Stepherd, M.; Kiso, M.; Hasegawa, Α.; Renkonen, R.; Nortamo, P.; Altieri, D. C.; Gamberg, C. G. Glycobiology 1993, 3, pp 131. 28. Larkin, M.; Ahern, T. J.; Stoll, M. S.; Shaffer, M.; Sako, D.; O'Brien, J.; Yuen, C. T.; Lawson, A. M.; Childs, R. Α.; Barone, K. M.; Langer-Safer, P. R.; Hasegawa, Α.; Kiso, M.; Larsen, G. R.; Feizi, T. J. Biol. Chem. 1992, 269, pp 13661. 29. Hanisch, F. G.; Hanski, C.; Hasegawa, A. Cancer Res. 1992, 52, pp 3138. 30. Foxall, C.; Watson, S. R.; Dowbenko, D.; Fennie, C.; Lasky, L, Α.; Kiso, M.; Hasegawa, Α.; Asa, D.; Brandley, Β. K. J. Cell Biol. 1992, 117, pp 895. 31. Tanaka, Α.; Ohmori, K.; Yoneda, T.; Tsuyuoka, K.; Hasegawa, Α.; Kiso, M.; Kannagi, R. Cancer Res. 1993, 53, pp 354. 32. Ohmori, K.; Tanaka, Α.; Yoneda, T.; Buma, Y.; Hirashima, K.; Tsuyuoka, K.; Hasegawa, Α.; Kannnagi, R. Blood 1993, 81, pp 101. 33. Kameyama, Α.; Ishida, H.; Kiso, M.; Hasegawa, A. Carbohydr. Res. 1991, 209, pp c1; ibid. J. Carbohydr. Chem. 1991,10, pp 549. 34. Kameyama, Α.; Ishida, H.; Kiso, M.; Hasegawa, A. J. Carbohydr. Chem. 1991, 10, pp 729. 35. Kameyama, Α.; Ishida, H.; Kiso, M.; Hasegawa, A. Carbohydr. Res. 1990, 193, pp 269. 36. Garegg, P. J.; Hultberg, H.; Wallin, S. Carbohydr. Res. 1982, 108, pp 97.



11. HASEGAWA


37. Jansson, K.; Ahlfors, S.; Frejd, T.; Kihlberg, J.; Gagnusson, G.; Dahmen, J.; Noori, G.; Stenvall, K. J. Org. Chem. 1988, 53, pp 5629. 38. Schmidt, R. R.; Michel, J. Angew. Chem. Int. Ed. Engl. 1980, 19, 731. 39. Ito, Y.; Kiso, M.; Hasegawa, A. J. Carbohydr. Chem. 1989, 8, pp 285. 40. Schmidt, R. R.; Zimmermann, P. Angew. Chem. Int. Ed. Engl. 1986, 25, pp 725. 41. Hasegawa, Α.; Hotta, K.; Kameyama, Α.; Ishida, H.; Kiso, M. J. Carbohydr. Chem. 1991, 10, 439. 42. Hasegawa, Α.; Ando, T.; Kameyama, Α.; Kiso, M. Carbohydr. Res. 1992, 230, pp c1; ibid. J. Carbohydr. Chem. 1992, 11, pp 645. 43. Yoshida, M.; Uchimura, Α.; Kiso, M.; Hasegawa, A. Glycoconjugate J. 1993, 10, pp 3. 44. Murase. T.; Ishida, H.; Kiso, M.; Hasegawa, A. Carbohydr. Res. 1989, 188, pp 71. 45. Furui, H.; Kiso, M.; Hasegawa, A. Carbohydr. Res. 1991, 229, pp c1. Received November 17, 1993


197

Synthesis of Sialo-oligosaccharides and Their Ceramide Derivatives

Recommend Documents