Stereoselective synthesis of carbon-sulfur-bridged glycomimetics by photoinitiated thiol-ene coupling reactions

Magdolna Csávás, Dániel Eszenyi, Erika Mező, László Lázár, Nóra Debreczeni, Marietta Tóth, László Somsák, Anikó Borbás

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Abstract

Oligosaccharides and glycoconjugates are abundant in all living organisms, taking part in a multitude of biological processes. The application of natural O-glycosides in biological studies and drug development is limited by their sensitivity to enzymatic hydrolysis. This issue made it necessary to design hydrolytically stable carbohydrate mimetics, where sulfur, carbon, or longer interglycosidic connections comprising two or three atoms replace the glycosidic oxygen. However, the formation of the interglycosidic linkages between the sugar residues in high diastereoslectivity poses a major challenge. Here, we report on stereoselective synthesis of carbon-sulfur-bridged disaccharide mimetics by the free radical addition of carbohydrate thiols onto the exo-cyclic double bond of unsaturated sugars. A systematic study on UV-light initiated radical mediated hydrothiolation reactions of enoses bearing an exocyclic double bond at C1, C2, C3, C4, C5, and C6 positions of the pyranosyl ring with various sugar thiols was performed. The effect of temperature and structural variations of the alkenes and thiols on the efficacy and stereoselectivity of the reactions was systematically studied and optimized. The reactions proceeded with high efficacy and, in most cases, with complete diastereoselectivity producing a broad array of disaccharide mimetics coupling through an equatorially oriented methylensulfide bridge.

Original languageEnglish
Article number573
JournalInternational journal of molecular sciences
Volume21
Issue number2
DOIs
Publication statusPublished - Jan 2 2020

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Keywords

  • C-glycoside
  • Carbohydrate
  • Diastereoselective synthesis
  • Disaccharide
  • Glycomimetic
  • Photochemical addition
  • Thioglycoside
  • Thiyl radical

ASJC Scopus subject areas

  • Catalysis
  • Molecular Biology
  • Spectroscopy
  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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