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Stereoelectronic effects determine oxacarbenium vs ?-sulfonium ion mediated glycosylations.

ABSTRACT: Activation of a glycosyl donor protected with a 2-O-(S)-(phenylthiomethyl)benzyl ether chiral auxiliary results in the formation of an anomeric ?-sulfonium ion, which can be displaced with sugar alcohols to give corresponding ?-glycosides. Sufficient deactivation of such glycosyl donors by electron-withdrawing protecting groups is, however, critical to avoid glycosylation of an oxacarbenium ion intermediate. The latter type of glycosylation pathway can also be suppressed by installing additional substituents in the chiral auxiliary.

SUBMITTER: Boltje TJ

PROVIDER: S-EPMC3076600 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Stereoelectronic effects determine oxacarbenium vs β-sulfonium ion mediated glycosylations.

Boltje Thomas J TJ Kim Jin-Hwan JH Park Jin J Boons Geert-Jan GJ

Organic letters 20101215 2

Activation of a glycosyl donor protected with a 2-O-(S)-(phenylthiomethyl)benzyl ether chiral auxiliary results in the formation of an anomeric β-sulfonium ion, which can be displaced with sugar alcohols to give corresponding α-glycosides. Sufficient deactivation of such glycosyl donors by electron-withdrawing protecting groups is, however, critical to avoid glycosylation of an oxacarbenium ion intermediate. The latter type of glycosylation pathway can also be suppressed by installing additional ...[more]

PMID: 21158475

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