Dioxane-type (2-naphthyl)methylene acetals of glycosides and their hydrogenolytic transformation into 6-O- and 4-O-(2-naphthyl)methyl (NAP) ethers

Anikó Borbás, Zoltán B. Szabó, László Szilágyi, Attila Bényei, András Lipták

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30 Citations (Scopus)

Abstract

α-, β-D-Gluco-, galacto-, 2-deoxy-2-phthalimido-β-D-glucopyranosides with different aglycons (methyl, allyl, p-methoxyphenyl, thioethyl) reacted with 2-naphthaldehyde dimethyl acetal to give rise to 4,6-O-(2-naphthyl)methylene acetals. The acetals were converted into fully protected compounds bearing benzoyl, benzyl, allyl, p-methoxybenzyl groups. The fully alkylated dioxane-type acetals were hydrogenolysed with AlH3 (3LiAlH4-AlCl3) reagent to furnish 4-O-NAP/6-OH derivatives. All acetals were treated with BH3·Me3N-AlCl3 in THF and a reverse regioselectivity was observed, producing 6-O-NAP/4-OH derivatives. Similar regioselectivity was also observed by using NaCNBH3-HCl reagent. In all reactions very mild reaction conditions were required, regioselectivity was better than 93:7, and the isolated yields were between 83-92%. All compounds were characterised by 1H and 13C NMR spectra. Solid-state and solution conformation of methyl 2,3-di-O-acetyl-4,6-O-(2-naphthyl)methylene-α-D-galactopyranoside were elucidated by X-ray and NMR measurements.

Original languageEnglish
Pages (from-to)5723-5732
Number of pages10
JournalTetrahedron
Volume58
Issue number28
DOIs
Publication statusPublished - Jul 8 2002

Keywords

  • Acetals
  • Glycosides
  • Sugars

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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