Stereoselective synthesis of a model alpha-glycoside of the beta-D-ManNAcp-(1-->4)-d-Glc disaccharide starting from lactose, avoiding the beta-mannosaminylation step.
A model isopropyl alpha-glycoside of the beta-d-ManNAc-(1-->4)-d-Glc disaccharide has been prepared from lactose, avoiding the beta-mannosaminylation step. Three complementary approaches involving first the preparation and then the glycosidation of beta-thiophenyl donors of the protected disaccharides, (a) beta-d-ManNAc-(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 alpha-isopropyl glycoside to an amination with inversion in position 2' followed by an epimerization at C-4'.
Attolino
Emanuele
E
Dipartimento di Chimica Bioorganica e Biofarmacia, Università di Pisa, Via Bonanno 33, I-56126 Pisa, Italy.
Bonaccorsi
Filippo
F
Catelani
Giorgio
G
D'Andrea
Felicia
F
D002621:Chemistry / Q000379:methods; D004187:Disaccharides / Q000138:chemical synthesis / Q000737:chemistry; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry*; D006031:Glycosylation; D007785:Lactose / Q000737:chemistry*; D008358:Mannose / Q000737:chemistry*; D008956:Models, Chemical; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature; D013865:Thioglycosides / Q000737:chemistry
D004187:Disaccharides; D006027:Glycosides; D012997:Solvents; D013865:Thioglycosides; D007785:Lactose; D008358:Mannose