Hp. Wessel et al., SYNTHETIC ALPHA,BETA-(1-]4)-GLUCAN OLIGOSACCHARIDES AS MODELS FOR HEPARAN-SULFATE, Journal of carbohydrate chemistry, 14(8), 1995, pp. 1101-1115
alpha,beta-(1-->4)-Glucans were devised as models for heparan sulfate
with the simplifying assumptions that carboxyl-reduction and sulfation
of heparan sulfate does not decrease the SMC antiproliferative activi
ty and that N-sulfates in glucosamines can be replaced by O-sulfates.
The target oligosaccharides were synthesized using maltosyl building b
locks. Glycosylation of methyl 2,3,6,2',3',6'-hexa-O-benzyl-beta-malto
side (1) with hepta-O-acetyl-alpha-maltosyl bromide (2) furnished tetr
asaccharide 3 which was deprotected to -(1-->4)-alpha-D-Glc-(1-->4)-be
ta-D-Glc-(1-->OCH3) (5) or, alternatively, converted to the tetrasacch
aride glycosyl acceptor (8) with one free hydroxyl function (4 ''''-OH
). Further glycosylation with glucosyl or maltosyl bromide followed by
deblocking gave the pentasaccharide -->4)-alpha-D-Glc-(1-->)](2)-beta
-D-Glc-(1-->OCH3) (11) and hexasaccharide ->4)](2)-alpha-D-Glc-(1-->4)
-beta-D-Glc-(1-->OCH3) (14). The protected tetrasaccharide 3 and hexas
accharide 12 were fully characterized by H-1 and C-13 NMR spectroscopy
. Assignments were possible using 1D TOCSY, T-ROESY, H-1,H-1 2D COSY s
upplemented by H-1-detected one-bond and multiple-bond H-1, C-13 2D CO
SY experiments.