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

Naruki Konishi, Tatsuya Shirahata, Yuki Yoshida, Noriko Sato, Eisuke Kaji, Yoshinori Kobayashi

Carbohydrate research 2021 Dec

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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. Copyright © 2021 Elsevier Ltd. All rights reserved.

Citation

Naruki Konishi, Tatsuya Shirahata, Yuki Yoshida, Noriko Sato, Eisuke Kaji, Yoshinori Kobayashi. Efficient synthesis of diverse C-3 monodesmosidic saponins by a continuous microfluidic glycosylation/batch deprotection method. Carbohydrate research. 2021 Dec;510:108437