Synthesis of N-acetyllactosamine-terminated oligosaccharides - Fragments of glycoprotein O-chains

Article abstract of DOI:10.1070/MC2002v012n05ABEH001653

The pentasaccharide Ga1β1-4G1cNAcβ1-6(Ga1β1-4G1cNAcβ1-3)Ga1NAcαOR, its partial trisaccharides Ga1β1-4G1cNAcβ1-3Ga1NAcαOR and Ga1β1-4G1cNAcβ1-6Ga1NAcαOR and the tetrasaccharide Ga1β1-4G1cNAcβ1-6(Ga1β1-3)Ga1NAcαOR were synthesised as spacered derivatives (R = CH₂CH₂CH₂NH₂) using a Troc-protected lactosamine glycosyl donor at the key stage.

Full text of DOI:10.1070/MC2002v012n05ABEH001653

Mendeleev Commun., 2002, 12(5), 183–184
Synthesis of N-acetyllactosamine-terminated oligosaccharides —
fragments of glycoprotein O-chains
Galina V. Pazynina, Vyacheslav V. Severov and Nicolai V. Bovin*
M. M. Shemyakin–Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences,
117997 Moscow, Russian Federation. Fax: +7 095 330 5592; e-mail: bovin@carb.siobc.ras.ru
10.1070/MC2002v012n05ABEH001653
The pentasaccharide Galβ1-4GlcNAcβ1-6(Galβ1-4GlcNAcβ1-3)GalNAcαOR, its partial trisaccharides Galβ1-4GlcNAcβ1-
3GalNAcαOR and Galβ1-4GlcNAcβ1-6GalNAcαOR and the tetrasaccharide Galβ1-4GlcNAcβ1-6(Galβ1-3)GalNAcαOR were
synthesised as spacered derivatives (R = CH2CH2CH2NH2) using a Troc-protected lactosamine glycosyl donor at the key stage.
Eight different cores, i.e., regions connected with Ser or Thr
Galβ1-4GlcNAcβ1-3GalNAcαO–CH2CH2CH2NH2
1
2
3
4
of glycoprotein O-chains, are known.1 Recently,2 we reported
the synthesis of oligosaccharides repeating four core struc-
tures, i.e., GlcNAcβ1-3GalNAcαOR (core 3), GlcNAcβ1-3-
(GlcNAcβ1-6)GalNAcαOR (core 4), GlcNAcβ1-6GalNAcαOR
(core 6) and Galβ1-3(GlcNAcβ1-6)GalNAcαOR (core 2); R =
= CH2CH2CH2NH2.
Galβ1-4GlcNAcβ1-6
GalNAcαO–CH2CH2CH2NH2
Galβ1-4GlcNAcβ1-3
Galβ1-4GlcNAcβ1-6GalNAcαO–CH2CH2CH2NH2
Galβ1-4GlcNAcβ1-6
GalNAcαO–CH2CH2CH2NH2
Galβ1-3
GlcNAcβ1-3GalNAcαO-Ser/Thr
(core 3)
(core 4)
(core 6)
(core 2)
GlcNAcβ1-6
GalNAcαO-Ser/Thr
GlcNAcβ1-3
Here, we describe the synthesis of more complex oligo-
saccharides, namely, containing an additional terminal β-Gal
moiety, as spacered compounds 1–4 suitable for further trans-
formations into various glycoprobes.3 The above core glyco-
peptides have been identified in mucin-type glycoproteins; e.g.,
core 6 structure is a cancer-associated antigen4 and core 4
GlcNAcβ1-6GalNAcαO-Ser/Thr
GlcNAcβ1-6
GalNAcαO-Ser/Thr
Galβ1-3
O
AcO
AcO
Ph
HO
AcO
O
O
O
OAc
HO
O
OAc
O
OAc
OH
O
O(CH2)3NHCOCF3
NHAc
O(CH2)3NHCOCF3
NHAc
Br
HNTroc
OAc
5
6
9
R2O
R2O
R2O
R2O
R2O
O
R2O
O
R4O
R4O
O
O
O
AgOTf, Me2NCONMe2
6 + 9
OR2
AgOTf, Me2NCONMe2
OR2
HO
O
O
5 + 6
OR2
O
OR2
O
OR2
O
OR2
OR2
OR1
NHAc
OR1
NHAc
HNR3
HNR3
7 R1 = (CH2)3NHCOCF3, R2 = Ac, R3 = Troc, R4 = PhCH, 84%
12 R1 = (CH2)3NHCOCF3, R2 = Ac, R3 = Troc, 78%
i
iii, iv, v
R1 = (CH2)3NHCOCF3, R2 = Ac, R3 = Troc, R4 = H, 72%
R1 = (CH2)3NH2, R2 = H, R3 = Ac, 74%
8
3
ii, iii,
iv, v
1 R1 = (CH2)3NH2, R2 = R4 = H, R3 = Ac, 75%
R2O
R2O
R2O
OR2
O
R2O
O
R2O
O
OR2
OR2
O
OR2
O
OAc
HO
OR2
O
AgOTf, Me2NCONMe2
OR2
6 + 8
OR2
AcO
HO
O
R2O
R2O
HNR3
HNR3
O
OAc
R2O
O
R2O
R2O
6
O
+
OR1
O
O
O
OR2
HO
O
HO
O
OAc
14
OR2
O
OR2
NHAc
O
O
O
OR2
OR1
NHAc
OR1
NHAc
HNR3
OR2
10 R1 = (CH2)3NHCOCF3, R2 = Ac, R3 = Troc, 71%
15 R1 = (CH2)3NHCOCF3, R2 = Ac, R3 = Troc, 65%
iii, iv, v
iii, iv, v
R1 = (CH2)3NH2, R2 = H, R3 = Ac, 50%
R1 = (CH2)3NH2, R2 = H, R3 = Ac, 48%
2
4
Scheme 1 Reagents and conditions: i, AcOH; ii, Ac2O, Py; iii, Zn, AcOH, Ac2O; iv, MeONa, MeOH; v, NaOH, H2O.
– 183 –

Mendeleev Commun., 2002, 12(5), 183–184
References
trisaccharide is probably a crypted carcinoma-associated Tk
antigen.5 Core 2 oligosaccharide is the specific motif, which
defines P-selectin binding properties6 of SiaLex-containing
glycoprotein PSGL-1. Gal-terminated oligosaccharides 1–4
are potential ligands for galectins, the family of β-galactoside
binding lectins, whose natural cellular ligands are not yet
clarified.
We used 3'-trifluoroacetamidopropyl 2-acetamido-4,6-O-
benzylidene-2-deoxy-α-D-galactopyranoside 5, which was de-
scribed previously,7 as a starting building block. To synthesise
trisaccharide 1, compound 5 reacted with bromide 6 (Scheme 1).
Resulting trisaccharide 7 was used as the starting material in the
synthesis of pentasaccharide 2: it was 4,6-O-debenzylidenated,
and obtained diol 8 was glycosylated regioselectively at the
6-position with bromide 6. To synthesise trisaccharide 3, the 3-OH
group in compound 5 was protected by acetylation, the ben-
zylidene group was removed and the obtained diol 9 was
6-O-glycosylated as described above. Tetrasaccharide 4 was syn-
thesised by 6-O-regioselective glycosylation of disaccharide
148 with bromide 6.
1 E. F. Hounsell, M. J. Davies and D. V. Renouf, Glycoconjugate J., 1996,
13, 19.
2 G. V. Pazynina and N. V. Bovin, Mendeleev Commun., 2000, 132.
3 N. V. Bovin, Glycoconjugate J., 1998, 15, 431.
4 Y. Yamashita, Y. S. Chung, R. Horie, R. Kannagi and M. Sowa, J. Natl.
Cancer. Inst., 1995, 87, 441.
5 M. Meichenin, J. Rocher, O. Galanina, N. Bovin, N. Nifant’ev, A. Sherman,
E. Cassagnau, M. F. Heymann, J. Bara, R. H. Fraser and J. le Pendu,
Cancer Res., 2000, 60, 5499.
6 P. Mehta, R. D. Cummings and R. P. McEver. J. Biol. Chem., 1998, 273,
32506.
7 N. V. Bovin, T. V. Zemlyanukhina and A. Ya. Khorlin, Bioorg. Khim.,
1986, 12, 533 [Sov. J. Bioorg. Chem. (Engl. Transl.), 1986, 12, 282].
8 N. V. Bovin, T. V. Zemlyanukhina and A. Ya. Khorlin, Bioorg. Khim.,
1985, 11, 1256 (in Russian).
9 V. Ellervik and G. Magnusson, Carbohydr. Res., 1996, 280, 251.
In all cases, N-Troc-protected lactosaminyl bromide 6 (Troc
is 1,1,1-trichloroethyloxycarbonyl),9 obtained by acetylation
and subsequent bromine treatment of the corresponding com-
mercial ethyl thioglycoside, was used for stereocontrolled
β-glycosylation. This choice is stipulated by good yields, high
β-stereoselectivity of glycosylation,2,9 and compatibility of this
protection with other protecting groups used in the synthesis.
Preparative yields in glycosylation with this reagent are noted
in Scheme 1, and they are comparable with published data.9
β-Stereoselectivity of glycosylation with donor 6 was con-
firmed by the corresponding J1,2 (8.0–9.5 Hz). The structures of
1
synthesised oligosaccharides were confirmed by H NMR data
using homonuclear correlation spectroscopy and conventional
analysis of coupling constants.†
Deprotection of sugar moieties and the spacer-arm by con-
ventional methods (Scheme 1) gave rise to oligosaccharides
1–4 as 3-aminopropyl glycosides; the synthesis of these oligo-
saccharides in the convenient spacered form has not been
described earlier.
Compounds 1–4 coupled with fluorescein-labelled poly-
acrylamide were used for the study of malignant cell galectins,
the data will be published elsewhere.
Received: 31st July 2002; Com. 02/1980
Galb1-4GlcNAcb1-6GalNAca1-O(CH2)3NH2 3: 1H NMR (500 MHz,
D2O) d: 4.865, (d, 1H, H-1 GalNAc, J1,2 3.7 Hz), 4.526 (d, 1H, H-1
GlcNAc, J1,2 8.1 Hz), 4.453 (d, 1H, H-1 Gal, J1,2 7.9 Hz), 4.139 (dd, 1H,
H-2 GalNAc, J1,2 3.7 Hz, J2,3 11.0 Hz), 4.069 (dd, 1H, H-6a GalNAc,
J5,6a 3.2 Hz, J6a6b 10.8 Hz), 3.96–4.01 (m, 2H, H-6a GlcNAc, H-6b
GalNAc), 3.953 (dd, 1H, H-4 GalNAc, J3,4 3.2 Hz, J4,5 £ 1 Hz), 3.909
(dd, 1H, H-4 Gal, J3,4 3.4 Hz, J4,5 £ 1 Hz), 3.884 (dd, 1H, H-3 GalNAc,
J3,4 3.2 Hz, J2,3 11.0 Hz), 3.825 (dd, 1H, H-6b GlcNAc, J5,6b 4.9 Hz, J6a6b
12.5 Hz), 3.66–3.79 (m, 8H, H-2, H-3, H-4 GlcNAc, H-5, H-6a, H-6b
Gal, H-5 GalNAc, OCH sp), 3.648 (dd, 1H, H-3 Gal, J3,4 3.4 Hz, J2,3
9.8 Hz), 3.593 (m, 1H, H-5 GlcNAc), 3.527 (dd, 1H, H-2 Gal, J1,2 7.9 Hz,
J2,3 9.8 Hz), 3.46–3.53 (m, 1H, OCH2 sp), 3.104 (m, 2H, NCH2 sp),
2.022 (s, 3H, NHCOMe), 2.002 (s, 3H, NHCOMe), 1.91–2.01 (m, 2H,
CH2 sp). MS, m/z: 666 (643 + 23) (M+ + Na+). [a]D +42 (c1, H2O).
Galb1-4GlcNAcb1-6(Galb1-3)GalNAca1-O(CH2)3NH2 4: 1H NMR
(500 MHz, D2O) d: 4.900 (d, 1H, H-1 GalNAc, J1,2 3.7 Hz), 4.557 (d,
1H, H-1 GlcNAc, J1,2 8.2 Hz), 4.491 (d, 1H, H-1 Galβ1-3, J1,2 8.1 Hz),
4.474 (d, 1H, H-1 Galβ1-4, J1,2 9.0 Hz), 4.350 (dd, 1H, H-2 GalNAc,
J1,2 3.7 Hz, J2,3 11.0 Hz), 4.245 (dd, 1H, H-4 GalNAc, J4,5 £ 1 Hz, J3,4
2.3 Hz), 4.114 (dd, 1H, H-6a GalNAc, J5,6a 2 Hz, J6a6b 10.5 Hz), 3.99–
4.08 (m, 3H, H-3 and H-6b GalNAc, H-6a GlcNAc), 3.947 (dd, 1H, H-4
Galβ1-4, J3,4 3.2 Hz, J4,5 < 1 Hz), 3.927 (dd, 1H, H-4 Galβ1-3, J3,4
3.1 Hz, J4,5 £ 1 Hz), 3.862 (dd, 1H, H-6b GlcNAc, J5,6b 4.9 Hz, J6a6a
12.3 Hz), 3.70–3.83 (m, 11H, H-5 GalNAc, H-2, H-3, H-4 GlcNAc,
2H-5, 2H-6a, 2H-6b, Gal, OCH sp), 3.685 (dd, 1H, H-3 Galβ1-4, J2,3
10.0 Hz, J3,4 3.2 Hz), 3.634 (dd, 1H, H-3 Galβ1-3, J3,4 3.2 Hz, J2,3 9.8 Hz),
3.60–3.66 (m, 1H, H-5 GlcNAc), 3.51–3.59 (m, 3H, 2H-2 Gal, OCH sp),
3.152 (m, 2H, NCH2 sp), 2.040 (s, 3H, NHCOMe), 1.90–2.10 (m, 2H,
CH2 sp). MS, m/z: 828 (805 + 23) (M+ + Na+). [a]D +40 (c1, H2O).
This work was supported in part by NIH (grant no.
1U54GM62116).
†
Galb1-4GlcNAcb1-3GalNAca1-O(CH2)3NH2 1: 1H NMR (500 MHz,
D2O) d: 4.778 (d, 1H, H-1 GalNAc, J1,2 3.9 Hz), 4.540 (d, 1H, H-1
GlcNAc, J1,2 7.6 Hz), 4.410 (d, 1H, H-1 Gal, J1,2 7.8 Hz), 4.196 (dd, 1H,
H-2 GalNAc, J1,2 3.9 Hz, J2,3 11.3 Hz), 4.151 (dd, 1H, H-4 GalNAc,
J3,4 2.7 Hz, J4,5 £ 1 Hz), 3.85–3.92 (m, 4H, H-3 and H-5 GalNAc, H-4 Gal,
H-6a GlcNAc), 3.781 (dd, 1H, H-6b GlcNAc, J5,6 4.7 Hz, J6a,6b 12.2 Hz),
3.63–3.76 (m, 9H, H-2, H-3, H-4 GlcNAc, H-5, H-6a, H-6b Gal, H-6a,
H-6b GalNAc, OCH2 sp), 3.607 (dd, 1H, H-3 Gal, J2,3 10.0 Hz, J3,4
3.5 Hz), 3.47–3.53 (m, 2H, H-5 GlcNAc, OCH2 sp), 3.475 (dd, 1H, H-2
Gal, J2,3 10.0 Hz, J1,2 7.8 Hz), 3.055 (m, 2H, NCH2 sp), 1.983 (s, 3H,
NHCOMe), 1.953 (s, 3H, NHCOMe), 1.940 (m, 2H, CH2 sp). MS, m/z:
666 (643 + 23) (M+ + Na+). [a]D +49 (c1, H2O).
Galb1-4GlcNAcb1-6(Galb1-4GlcNAcb1-3)GalNAca1-O(CH2)3NH2 2:
1H NMR (500 MHz, D2O) d: 4.515 (d, 1H, H-1 GlcNAc, J1,2 7.8 Hz),
4.453 (d, 1H, H-1 GlcNAc, J1,2 8.3 Hz), 4.391 (d, 2H, 2H-1 Gal, J1,2
7.8 Hz), 4.172 (dd, 1H, H-2 GalNAc, J1,2 3.7 Hz, J2,3 11.0 Hz), 4.124
(dd, 1H, H-4 GalNAc, J3,4 2.9 Hz, J4,5 £ 1 Hz), 4.077 (dd, 1H, H-6a
GalNAc, J5,6a 2.2 Hz, J
10.5 Hz), 3.85–3.96 (m, 6H, 2H-6a GlcNAc,
6a,6b
H-6a and H-3 GalNAc, 2H-4 Gal), 3.764 (dd, 2H, 2H-6b GlcNAc, J5,6b
4.9 Hz, J6a,6b 12.2 Hz), 3.60–3.73 (m, 14H, 2H-5, 2H-6a, 2H-6b Gal, 2H-2,
2H-3, 2H-4 GlcNAc, H-5 GalNAc, OCH sp), 3.586 (dd, 2H, 2H-3 Gal,
J3,4 3.4 Hz, J2,3 10.0 Hz), 3.532 (m, 1H, H-5 GlcNAc), 3.40–3.50 (m,
4H, H-5 GlcNAc, 2H-2 Gal, OCH sp), 3.045 (m, 2H, NCH2 sp), 1.963
(s, 3H, NHCOMe), 1.936 (s, 3H, NHCOMe), 1.934 (s, 3H, NHCOMe),
1.85–1.98 (m, 2H, CH2 sp). MS, m/z: 1031 (1008 + 23) (M+ + Na+).
[a]D +18 (c1, H2O).
– 184 –