Stereoselectivity in the Hydroboration of C4-C-Methylene Groups

Conditions for the hydroxylation of an exocyclic methylene group at C4 of a pyranoside ring via hydroboration have been examined with a view to determining the optimum procedure for obtaining the axially-oriented C4-CH 2 OH group. The regio- and stereochemical outcome of the reactions rely not only...

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Veröffentlicht in:Journal of carbohydrate chemistry 1987-09, Vol.6 (3), p.479-493
Hauptverfasser: Molino, Bruce F., Cusmano, John, Mootoo, David R., Faghih, Ramine, Fraser-reid, Bert
Format: Artikel
Sprache:eng
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Zusammenfassung:Conditions for the hydroxylation of an exocyclic methylene group at C4 of a pyranoside ring via hydroboration have been examined with a view to determining the optimum procedure for obtaining the axially-oriented C4-CH 2 OH group. The regio- and stereochemical outcome of the reactions rely not only on the hydroborating reagent used, but, to a surprising degree, on the nature of the protecting group at the "remote" C6-OH. Silyl ethers are preferred because the only by-product formed is the tertiary alcohol, which can be recycled through dehydration to the starting alkene by treatment with thionyl chloride.
ISSN:0732-8303
1532-2327
DOI:10.1080/07328308708057935