SYNTHETIC ALPHA,BETA-(1-]4)-GLUCAN OLIGOSACCHARIDES AS MODELS FOR HEPARAN-SULFATE .2.

alpha,beta-(1-->4)-Glucan oligosaccharides were prepared as models for heparan sulfate with the simplifying assumptions that carboxyl-reduct ion and sulfation of heparan sulfate does not decrease the SMC antipro liferative activity and that N-sulfates in glucosamines can be replace d by O-sulfates. The target saccharides were synthesized using maltosy l building blocks. Glycosylation of methyl 2,3,6-tri-O-benzyl-alpha-D- glucopyranoside (1) with hepta-O-acetyl-alpha-maltosyl bromide (2) fur nished trisaccharide 3 which was deprotected to pha-D-Glc-(1-->4)-beta -D-Glc-(1-->4)-alpha-D-Glc(1 --> OCH3) (5) or, alternatively, converte d to the trisaccharide glycosyl acceptor (8) with one free hydroxyl fu nction (4''-OH). Further silver triflate mediated glycosylation with g lucosyl or maltosyl bromide followed by deblocking gave the tetrasacch aride -Glc-(1-->4)-beta-D-Glc-(1-->4)-alpha-D-(1-->OCH3) (11) and the pentasaccharide -(1-->4)-beta-D-Glc-(1-->4)-alpha-D-Glc-(1-->OCH3) (14 ). The trisaccharides 3, 4, 6, and 8 as well as pentasaccharide 12 wer e fully characterized by H-1, 3, 8 and 12 also by C-13 NMR spectroscop y. Assignments were possible using 1D TOCSY, in some cases supplemente d by 2D T-ROESY, H-1,H-1 2D COSY, and H-1-detected one-bond and multip le-bond H-1,C-13 2D COSY experiments.