Facile Synthesis of Four Natural Triterpene Saponins with Important Antitumor Activity

Abstract

The first synthesis of four natural triterpene saponins, which exhibit significant antitumor activities, was concisely achieved by adopting a stepwise glycosylation. The key intermediate 13 was afforded via Bu₂SnO-mediated regioseletive benzoylation. During the preparation of the target compounds, it was found that the α-L-arabinopyranosyl unit in intermediates 17 and 20 existed in the unusual ¹ C ₄ conformation, and after removing the benzoyl groups, the α-L-arabinopyranosyl unit was normal in a typical ⁴ C ₁ form.

Keywords:

• Antitumor activities
• Bu₂SnO-mediated regioseletive benzoylation
• glycosylation
• glycosyl trichloroacetimidate
• triterpene saponins

ACKNOWLEDGMENT

This work is supported by the National Basic Research Program of China (30701046).