Section 5
Chapter 4,863

Building units of oligosaccharides 58. regioselective glycosylation at 3' hydroxyl groups or 4' hydroxyl groups of lactose using different catalyst systems

Paulsen, H.; Hadamczyk, D.; Kutschker, W.; Buensch, A.

Liebigs Annalen der Chemie 1: 129-141


Accession: 004862697

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The lactose derivative 4 with unsubstituted 3'-OH and 4'-OH groups makes regioselective glycosylation reactions possible depending on the chosen type of catalyst system. In the presence of silver triflate, 4 reacts in homogenic phase with the phthalimido bromide 1 to yield the .beta.(1 .fwdarw. 3)-glycosidically linked trisaccharide 5. The same compounds give in heterogenic phase with silver silicate regioselectively the .beta.(1 .fwdarw. 4)-glycosidically linked trisaccharide 7. In the presence of silver silicate, 4 reacts with the azido halide 2 to yield in heterogenic phase regioselectively the .beta.(1 .fwdarw. 4)-glycosidically linked product 17. In homogenic phase with silver perchlorate, however, the azido halides 2 and 3 yield the .alpha.-glycosidically linked products, following the in situ anomerization procedure.

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