Synthesis of 2-Deoxyglycosides Bearing Free Hydroxyl Substituents on the Glycosyl Donor.
J Org Chem
; 87(16): 10768-10790, 2022 08 19.
Article
em En
| MEDLINE
| ID: mdl-35921523
ABSTRACT
Recent efforts in the field of carbohydrate chemistry have focused on the site- and stereocontrolled synthesis of O-glycosides derived from acceptors bearing multiple hydroxyl substituents. By comparison, there are few examples of the site-selective synthesis of O-glycosides bearing free hydroxyl substituents on the donor reagent. Here, we report the application of an umpolung glycosylation strategy to the synthesis of O-glycosides derived from donors bearing free hydroxyl substituents. The reaction proceeds via prior deprotonation of one or more free hydroxyl groups on a thiophenylglycoside donor, reductive lithiation to generate an anomeric anion intermediate, and addition of this anion to an alkyl 2-(2-methyltetrahydropyranyl) peroxide. By this approach, α-linked glycosides were obtained in 39-84% yields and with >501 α/ß selectivities. In many instances, ß-linked products could be obtained by thermal equilibration of the anomeric anion intermediate (selectivities = 3.8-81 ß/α; yields = 33-68%). The strategy is applicable to polyhydroxyl donors bearing up to three free hydroxyl groups, N-acylated carbohydrates, and the single-flask syntheses of oligosaccharides.
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Base de dados:
MEDLINE
Assunto principal:
Carboidratos
/
Glicosídeos
Idioma:
En
Ano de publicação:
2022
Tipo de documento:
Article