Stereocontrolled synthesis and reactivity of sugar acetylenes

Minoru Isobe*, Rena Nishizawa, Seijiro Hosokawa, Toshio Nishikawa

*この研究の対応する著者

研究成果: Article査読

129 被引用数 (Scopus)

抄録

C-Glycosidation is of great significance in the organic synthesis of optically active materials, since it allows the introduction of carbon chains to sugar chirons and the use of sugar nuclei as a chiral pool as well as a carbon source. Silylacetylenes are sufficiently reactive to form 'sugar acetylenes' for the selective introduction of various acetylenic groups in an alpha-axial manner at the anomeric position of D-hexopyranose rings. 1,4-Anti induction, on the other hand, gives a different stereochemical outcome in the case of C-glycosidation of pentopyranose glycals. The mechanism of these reactions includes oxonium cation intermediates in which stereoelectronic and/or steric factors drive the direction of the incoming silylacetylene. Bis-C-glycosidation allows the introduction of sugars at both ends of some bis(trimethylsilyl)acetylenes. A 2,3-dideoxyglucose derivative provides the corresponding C-1 α-acetylenic compounds, which would increase the scope of C-glycosidation with silylacetylenes. In sugar acetylenes, the alkynyl group at the anomeric position of a pyranose ring is epimerized via a hexacarbonyldicobalt complex by treatment with trifluoromethanesulfonic acid. The three steps - cobalt complexation, acidic transformation and decomplexation - afford overall epimerization and thus one can obtain either the α- or β-alkynyl C-glycoside as desired. Ring opening of a dihydropyran derivative using Nicholas-type cation intermediates is also part of this study. Several sets of decomplexation conditions for endo-type acetylene-cobalt complexes provide various olefins possessing potential utility for synthesis. These methodologies have been utilized for the synthesis of polyoxygenated natural products and derivatives.

本文言語English
ページ(範囲)2665-2676
ページ数12
ジャーナルChemical Communications
24
DOI
出版ステータスPublished - 1998 12月 21
外部発表はい

ASJC Scopus subject areas

  • 触媒
  • 電子材料、光学材料、および磁性材料
  • セラミックおよび複合材料
  • 化学 (全般)
  • 表面、皮膜および薄膜
  • 金属および合金
  • 材料化学

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