Stereospecific β-l-Rhamnopyranosylation through an SNi-Type Mechanism by Using Organoboron Reagents

Nobuya Nishi, Kazuhiro Sueoka, Kiyoko Iijima, Ryuichi Sawa, Daisuke Takahashi, Kazunobu Toshima

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Stereospecific β-l-rhamnopyranosylations were conducted using a 1,2-anhydro-l-rhamnopyranose donor and mono-ol or diol acceptors in the presence of a glycosyl-acceptor-derived borinic or boronic ester. Reactions proceeded smoothly to provide the corresponding β-l-rhamnopyranosides (β-l-Rhap) with complete stereoselectivity in moderate to high yields without any further additives under mild conditions. Mechanistic studies of the borinic ester mediated glycosylation using 13C kinetic isotope effect (KIE) measurements and DFT calculations were consistent with a concerted SNi mechanism with an exploded transition state. In addition, the present glycosylation method was applied successfully to the synthesis of a trisaccharide, α-l-Rhap-(1,2)-β-l-Rhap-(1,4)-Glcp, derived from Streptococcus pneumoniae serotypes 7B, 7C, and 7D.

Original languageEnglish
Pages (from-to)13858-13862
Number of pages5
JournalAngewandte Chemie - International Edition
Volume57
Issue number42
DOIs
Publication statusPublished - 2018 Oct 15

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Keywords

  • carbohydrates
  • glycosylation
  • organoboron reagents
  • stereoselectivity
  • β-l-rhamnosylation

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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