József Szejtli

Synthesis of 6-O-α-d-glucopyranosylcyclomaltoheptaose

Abstract (2,3-Di- O -acetyl)hexakis(2,3,6-tri- O -acetyl)cyclomaltoheptaose was prepared by reaction of cyclomaltoheptaose with tert -butyldimethylsilyl chloride in pyridine followed by acetylation and desilylation. Glycosylation with 2,3,4,6-tetra- O -benzyl-1- O -trichloroacetimidoyl-α- d -glucopyranose, using trifluoromethanesulfonic acid as catalyst, and removal of the protecting groups from the product then afforded the title compound.

The regioselectivity of the reductive ring-cleavage of the acetal ring of 4,6-O-benzylidenehexopyranosides

Abstract The hydrogenolytic ring-cleavage of benzyl 4,6- O -benzylidene-β- d -glucopyranoside derivatives with LiAlH 4 -AlCl 3 was investigated in relation to the bulk of the C-3 substituents (H, OMe, OEt, OPr, OBzl). In ether-dichloromethane (2:1), 4-benzyl ethers were the major products, and the ratio of the 4- and 6-benzyl ethers was strongly dependent on the steric requirement of the C-3 substituent. Hydrogenolytic ring-cleavage with various reducing agents (AlH 2 Cl, AlH 2 Br, AlH 2 I, Bu 2 1 AlH, and borane) was also studied and the best selectivity was found with AlH 2 Br. The donor ability of the solvent has significant effects on the product ratios and the reaction rates in some reductions.

Investigation of the Hemolytic Effect of the Cyclodextrin Derivatives

The hemolytic effects of methylated cyclodextrins, cyclodextrin polymers and carboxymethylated cyclodextrins were measured. In the case of heptakis-(2,6-di-O-methyl)-β-cyclodextrin, different derivatives were synthetized, which had both ionic and non-ionic substituens at the position C-3. The ionic character of the molecules has an important role in the degree of the hemolysis of human erythrocytes, but it is not the only reason for the decrease in the hemolytic activity.