Synthesis of the pentasaccharide hapten from the glycopeptidolipid antigen of Mycobacterium avium serovar 12

Article abstract of DOI:10.1016/S0040-4039(02)00491-4

An effective synthesis of the pentasaccharide hapten from the glycopeptidolipid antigen of Mycobacterium avium serovar 12 in the protected p-nitrophenyl glycoside, using a 3+2 block synthesis strategy, is described.

Full text of DOI:10.1016/S0040-4039(02)00491-4

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 43 (2002) 3145–3148
Synthesis of the pentasaccharide hapten from the
glycopeptidolipid antigen of Mycobacterium avium serovar 12
Zsolt Varga,a Istva´n Bajza,b Gyula Battac and Andra´s Lipta´ka,b,
*
aDepartment of Biochemistry, University of Debrecen, PO Box 55, Debrecen H-4010, Hungary
bResearch Group for Carbohydrates of the Hungarian Academy of Sciences, PO Box 55, Debrecen H-4010, Hungary
cResearch Group for Antibiotics of the Hungarian Academy of Sciences, PO Box 70, Debrecen H-4010, Hungary
Received 28 December 2001; revised 28 February 2002; accepted 8 March 2002
Abstract—An effective synthesis of the pentasaccharide hapten from the glycopeptidolipid antigen of Mycobacterium avium
serovar 12 in the protected p-nitrophenyl glycoside, using a 3+2 block synthesis strategy, is described. © 2002 Elsevier Science
Ltd. All rights reserved.
Besides Mycobacterium tuberculosis1 and M. leprae,2,3
the agents of human tuberculosis and leprosy, respec-
tively, another ‘atypical’ or ‘opportunistic’ mycobac-
teria may also cause infections in humans.4 Infections
with the M. avium serocomplex are seen in up to 50%
of the patients with AIDS in some areas of the world.5–7
The antigens of various serovars of M. avium are
glycopeptidolipids (GPLs) located in the outer cell sur-
face of these bacteria, whose structures can be
described by a general formula8 (Fig. 1).
In this paper we report the synthesis of the protected
pentasaccharide hapten of the M. avium serovar 1210
carrying a p-nitrophenyl spacer. The structure of the
protected hapten 1 is shown in Fig. 2.
The synthesis of the unprotected diastereoisomeric ter-
minal trisaccharides with
D- and L-lactamido groups in
position 4%% was described by van Boom’s group11 using
3-aminopropyl as the spacer.
One of the most difficult tasks was the synthesis of the
These outer oligosaccharide haptens are responsible for
the immunological properties of the bacteria, thus these
haptens, after conjugation with suitable proteins, might
aid the serodiagnosis of mycobacterial infections. The
synthesis of different oligosaccharide haptens and their
conjugation to proteins have been recently reviewed.8,9
3-O-methyl ether of
D
-viosamin (4-amino-4,6-dideoxy-
D
-glucose). Regioselective 3-O-methylation of ethyl 2-
O-benzoyl-1-thio-a-D-fucopyranoside by means of the
3,4-O-stannylidene acetal protocol was reported,11
however this procedure did not work in our hands. To
overcome these difficulties we started from allyl a-
fuco-pyranoside12 2, and using the orthoester methodol-
-fucopyranoside 3 was
D-
ogy,13 allyl 2,4-di-O-benzoyl-a-
D
obtained in a one-pot three-step reaction sequence
(Scheme 1). The 3-OH was then methylated with diazo-
14
methane in the presence of BF3·OEt2 giving 4.
It is well documented that the isolated 2-O-acyl groups
of pyranosides are stable under the conditions of the
Zemple´n transacylation reaction.15–17 Glaudemans et al.
showed that an O-acyl group at position 3 was also
stable under Zemple´n’s conditions, when position 2 is
deoxygenated and position 4 is blocked.18 We found
that the 2-O-benzoate of 4 is more reactive than the
4-OBz, and could be selectively removed under Zem-
ple´n’s conditions, and the deacylated product 5 proved
to be a useful intermediate. The allyl group was isomer-
Figure 1.
Keywords: oligosaccharide; glycopeptidolipid; block synthesis;
regioselective Zemple´n deacylation; M. avium serovar 12.
* Corresponding author. Tel.: +36-52-512-913; fax: +36-52-512-913;
e-mail: liptaka@tigris.klte.hu
0040-4039/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(02)00491-4

3146
Z. Varga et al. / Tetrahedron Letters 43 (2002) 3145–3148
transformed into the trichloroacetimidate 11 using the
standard Schmidt procedure.20
The next unit of the pentasaccharide was synthesized
from phenyl 2,3-O-isopropylidene-1-thio-a-L-rhamno-
pyranoside 1221 by methylation of 4-OH (“13) fol-
lowed by the hydrolysis of the isopropylidene group
(“14) and phase transfer catalyzed selective
benzylation22 of the 2-OH (“15). Glycosylation of 15
with the imidate 11 yielded the azido derivative 16 of
the terminal disaccharide (Scheme 2).
Our original intent was to use the disaccharide donor
16 for the 2+3 block synthesis of the pentasaccharide.
However during the synthesis of an analogous oligosac-
charide it was observed23 that glycosylation of the
trisaccharide acceptor 19 with any glycosyl donor
failed, but its earlier synthesized24 disaccharide part 20
reacted readily under various glycosylation conditions
(Fig. 3).
Figure 2.
ized to propenyl and then the enol ether was trans-
formed to the 1,2-O-propylidene acetal19 6. Compound
6 was treated with equimolar NaOMe to obtain the
4-OH derivative 7, which was triflated (“8) and a
subsequent nucleophilic displacement with LiN3
resulted in the
D
-gluco epimer 9.
Acid hydrolysis of the propylidene acetal and direct
acetylation of the diol formed gave 10 which was
Figure 3.
Scheme 1. (a) i. PhC(OEt)3, CSA, MeCN; ii. BzCl, pyridine; iii. AcOH/H2O, 72% for three steps; (b) CH2N2, BF3·Et2O, 84%; (c)
NaOMe, MeOH, 87% (d) i. (Ph3P)3RhCl, DABCO, EtOH-toluene-H2O; ii. CSA, CH2Cl2, 52% for two steps; (e) NaOMe, MeOH;
quant. (f) Tf2O, pyridine; (g) LiN3, DMF, 81% for two steps; (h) i. TFA, H2O, CH2Cl2; ii. Ac2O, pyridine, 60% for two steps;
(i) i. hydrazine acetate, DMF; ii. CCl3CN, K2CO3, CH2Cl2, 91% for two steps.
Scheme 2. (a) MeI, KOH, DMF, 90%; (b) CF3COOH, H2O, CH2Cl2, 98%; (c) BzlBr, NaOH, Bu4NBr, CH2Cl2-H2O, 89%; (d)
TMSOTf, CH2Cl2, −40°C, 63%; (e) NBS, aq. acetone, 83%; (f) CCl3CN, K2CO3, CH2Cl2, quantitative.

Z. Varga et al. / Tetrahedron Letters 43 (2002) 3145–3148
3147
Scheme 3. (a) TMSOTf, CH2Cl2, −60°C, 74%; (b) NIS/TfOH, CH2Cl2-THF, −50°C, 50%.
stereoselectively, which was isolated in 50% yield
(Scheme 3).
Based on these experiences the thioglycoside 16 was
treated with NBS in aqueous acetone25 to yield the
hemiacetal 17 which was then converted into imidate 18
(Scheme 2).
The structures of all intermediates and the end-product
were unambiguously confirmed by one and two dimen-
sional 1H and 13C NMR spectroscopic methods.
Selected NMR data (CD3OD, Bruker DRX 500) for 1
is given in Table 1.
Glycosylation of ethyl 2,4-di-O-benzyl-1-thio-a-L-
rhamnopyranoside 2126 with 18 afforded the trisaccha-
ride-type glycosyl donor 22. The dimer 20 was
glycosylated with this trisaccharide under NIS/TfOH27
promotion to give the fully protected pentasaccharide 1
In conclusion, we have elaborated a new procedure for
the synthesis of the precursor of the terminal 4-amino-
4,6-dideoxy-3-O-methyl-
D
-glucose
(3-O-methyl-D-
Table 1. Selected NMR data of pentasaccharide 1 (l, ppm)
viosamine); observed and used a new type of the
anomalous Zemple´n deacylation; verified our earlier
observation concerning the very low reactivity of 3%%-
OH of the 19 trisaccharide acceptor. The 3%-OH of the
Residue
A
1H
13C
1
2
3
4
5.58
4.17
4.53
4.18
3.95
1.23
98.40
76.21
72.02
71.02
67.53
15.47
L
-rhamnosyl unit in the disaccharide acceptor 20
showed acceptable reactivity to achieve the synthesis of
the fully protected target pentasaccharide 1 using a 3+2
block synthesis.
5
CH3
JC1,H1
1
2
3
4
5
CH3
JC1,H1
1
2
3
4
5
CH3
JC1,H1
1
2
3
4
5
CH3
OCH3
JC1,H1
1
2
3
176.5 Hz
171.3 Hz
172.7 Hz
B
4.97
3.75
3.87
3.52
3.83
1.23
95.07
78.17
78.17
80.29
68.63
17.89
Acknowledgements
We thank the Howard Hughes Medical Institute and
the National Research Foundation (OTKA T035128)
for financial support.
C
D
4.94
3.66
4.01
3.43
3.70
1.07
99.20
78.88
78.88
80.29
68.63
17.89
References
1. Daffe´, M.; Lacave, C.; Lane´elle, M.-A.; Lane´elle, G. Eur.
J. Biochem. 1987, 167, 155–160.
2. Hunter, S. W.; Brennan, P. J. J. Bacteriol. 1981, 147,
728–735.
3. Hunter, S. W.; Fujiwara, T.; Brennan, P. J. J. Biol.
Chem. 1982, 257, 15072–15078.
4. Wolinsky, E. Am. Rev. Respir. Dis. 1979, 119, 107–159.
5. Wolinsky, E.; Schaefer, W. B. Int. J. Syst. Bacteriol.
1973, 23, 102–183.
6. Good, R. C. Annu. Rev. Microbiol. 1985, 39, 347–369.
7. Blaser, M. J.; Cohn, D. L. Rev. Infect. Dis. 1986, 8,
21–30.
8. Lipta´k, A.; Borba´s, A.; Bajza, I. Rev. Med. Res. 1994, 14,
307–352.
4.94
3.72
3.80
3.16
3.62
1.12
3.38
100.65
78.59
79.89
81.97
68.63
17.89
60.75
173.0 Hz
E
4.47
4.91
3.18
101.50
73.25
83.40
66.72
70.37
18.28
60.01
4
5
3.00–3.06
3.00–3.06
1.05
CH3
OCH3
JC1,H1
3.48
9. Aspinall, G. O.; Chatterjee, D.; Brennan, P. J. Adv.
Carbohydr. Chem. Biochem. 1995, 51, 169–242.
163.9 Hz

3148
Z. Varga et al. / Tetrahedron Letters 43 (2002) 3145–3148
10. Bozic, C. M.; McNeil, M.; Chatterjee, D.; Jardines, I.;
Brennan, P. J. J. Biol. Chem. 1988, 263, 14984–
14991.
11. Zegelaar-Jaarsveld, K.; van der Plas, S. C.; van der
Marel, G. A.; van Boom, J. H. J. Carbohydr. Chem. 1996,
15, 591–610.
18. Petrakova´, E.; Glaudemans, C. P. J. Carbohydr. Res.
1995, 268, 135–141.
19. Gigg, R.; Warren, C. D. J. Chem. Soc. (C) 1968, 1903–
1911.
20. Schmidt, R. R.; Michel, J. Angew. Chem. 1980, 92, 763–
764.
21. Pozsgay, V. Carbohydr. Res. 1992, 235, 295–302.
22. Pozsgay, V. Carbohydr. Res. 1979, 69, 284–286.
23. Varga, Z.; Bajza, I.; Batta, G.; Lipta´k, A. Tetrahedron
Lett. 2001, 42, 5283–5286.
12. Garegg, P. J.; Norberg, T. Carbohydr. Res. 1976, 52,
235–240.
13. Oscarson, S.; Szo¨nyi, M. J. Carbohydr. Chem. 1989, 8,
663–668.
24. Kere´kgya´rto´, J.; Szurmai, Z.; Lipta´k, A. Carbohydr. Res.
14. Mastronardi, J. O.; Flametti, S. M.; Deferrari, J. O.;
Gros, E. G. Carbohydr. Res. 1966, 3, 177–183.
15. Lipta´k, A.; Szurmai, Z.; Na´na´si, P.; Neszme´lyi, A. Car-
bohydr. Res. 1982, 99, 13–21.
1993, 245, 65–80.
25. Motawia, S. M.; Marcussen, J.; Møller, L. J. Carbohydr.
Chem. 1995, 14 (9), 1279–1294.
26. Bajza, I.; Kere´kgya´rto´, J.; Hajko´, J.; Szila´gyi, L.; Lipta´k,
A. Carbohydr. Res. 1994, 253, 111–120.
27. Veeneman, G. H.; van Leeuwen, S. H.; van Boom, J. H.
Tetrahedron Lett. 1990, 31, 1331–1334.
16. Szurmai, Z.; Kere´kgya´rto´, J.; Harangi, J.; Lipta´k, A.
Carbohydr. Res. 1987, 164, 313–325.
17. Szurmai, Z.; Lipta´k, A.; Snatzke, G. Carbohydr. Res.
1990, 200, 201–208.