Efficient synthesis of diverse C-3 monodesmosidic saponins by a continuous microfluidic glycosylation/batch deprotection method

Carbohydr Res. 2021 Dec:510:108437. doi: 10.1016/j.carres.2021.108437. Epub 2021 Sep 9.

Abstract

Triterpene and steroid saponins have various pharmacological activities but the synthesis of C-3 monodesmosidic saponins remains challenging. Herein, a series of C-3 glycosyl monodesmosidic saponins was synthesized via the microfluidic glycosylation of triterpenoids or steroids at the C-3 position, without the formation of orthoester byproducts, and subsequent deprotection of the benzoyl (Bz) group. This microfluidic glycosylation/batch deprotection sequence enabled the efficient synthesis of C-3 saponins with fewer purification steps and a shorter reaction time than conventional batch synthesis and stepwise microfluidic glycosylation. Furthermore, this system minimized the consumption of the imidate donor. Using this reaction system, 18 different C-3 saponins and 13 different C-28-benzyl-C-3 saponins, including 8 new compounds, were synthesized from various sugars and triterpenes or steroids. Our synthetic approach is expected to be suitable for further expanding the C-3 saponin library for pharmacological studies.

Keywords: Continuous synthesis; Glycosylation; Microreactor; Reaction integration; Saponin.

MeSH terms

  • Glycosylation
  • Microfluidic Analytical Techniques*
  • Molecular Conformation
  • Saponins / chemical synthesis*
  • Saponins / chemistry

Substances

  • Saponins