A model isopropyl a-glycoside of the beta-D-ManNAc-(1→4)-D-Glc disaccharide has been prepared from lactose, avoiding the b-mannosaminylation step. Three complementary approaches involving first the preparation and then the glycosidation of beta-thiophenyl donors of the protected disaccharides, (a) beta-DManNAc-(1→4)-D-Glc, (b) beta-D-TalNAc-(1→4)-D-Glc and (c) lactose, were compared. The best results were obtained employing a suitably protected lactose donor, and submitting its a-isopropyl glycoside to an amination with inversion in position 2’ followed by an epimerization at C-4’ .
Stereoselective synthesis of a model alfa-glycoside of the beta-D-ManNAcp-(1-->4)-D-Glc disaccharide starting from lactose, avoiding the beta-mannosaminylation step
CATELANI, GIORGIO;D'ANDREA, FELICIA
2008
Abstract
A model isopropyl a-glycoside of the beta-D-ManNAc-(1→4)-D-Glc disaccharide has been prepared from lactose, avoiding the b-mannosaminylation step. Three complementary approaches involving first the preparation and then the glycosidation of beta-thiophenyl donors of the protected disaccharides, (a) beta-DManNAc-(1→4)-D-Glc, (b) beta-D-TalNAc-(1→4)-D-Glc and (c) lactose, were compared. The best results were obtained employing a suitably protected lactose donor, and submitting its a-isopropyl glycoside to an amination with inversion in position 2’ followed by an epimerization at C-4’ .File in questo prodotto:
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