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2005
Carbohydrates
U 0500
Synthesis of 2-Amino-2-deoxy-β-D-galactopyranosyl-(1→4)-2-amino-2-deoxyUsing Various 2-Deoxy-2-phthalimido-D-galactopyra12- 208 −β-D-galactopyranosides:
nosyl Donors and Acceptors. — The efficiency of the most common glycosylation
methods is investigated using glycosyl donors such as (II) and glycosyl acceptors like
(I) and (V). Due to the low reactivity of the 4-OH group in a galactopyranose ring, the
stereoselectivity of glycosylation of D-galactosamine is lower in comparison with
D-glucosamine. In addition to the β(1→4)-linked disaccharides (III), disaccharides
(IV) are also formed. The best yields of β-linked disaccharides are achieved by glycosylation with glycosyl donor (II) in the presence of silver salts. A further result of the
low reactivity of the axially oriented 4-OH group is the intermolecular migration of the
ethylsulfanyl group from acceptor (V) to donor (II) yielding ethylsulfanyl derivatives
(VII). — (VESELY, J.; LEDVINA*, M.; JINDRICH, J.; TRNKA, T.; SAMAN, D.;
Collect. Czech. Chem. Commun. 69 (2004) 10, 1914-1938; Inst. Org. Chem.
Biochem., Acad. Sci. Czech Rep., CZ-166 10 Prague 6, Czech Republic; Eng.) —
H. Hoennerscheid
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