Studies On The Synthesis And Activities Of Furostan Saponins Derivatives

Lots of researches have showed that furostan saponins own various biological and pharmacological activities. However, there is little report about their synthesis until very recently. Carbohydrate-based compounds have been widely applied in pharmaceutical field and many carbohydrate-based drugs have been launched, so the structural modification of furostan saponins is hopeful for finding better activities leading compounds, which will have a deep influence on new drug research and development.We designed and synthesized fifteen derivatives of furostan saponins by using cheap D-glucopyranose, D-xylopyranose, L-rhamopyranose and diosgenin as starting materials. The whole synthetic route includes the preparation of sugar donors and the synthesis of aglycone moiety, in which such reactions as the silylation of hydroxyl, oxidation with DMDO, reductive cleavage and acetylation by Zn/KI and ACOH/AC₂O, selective cleavage of acetyl and alkylsilyl groups, the conformation of glycoside, reduction and concurrently cyclization with KBH₄ , the protection and dehydration of hydroxyl were involved. Given the structural type of natural products, we synthesized three different kinds of compounds, that are C₂₂-hydroxyl, C₂₂-methoxyl and C₂₀,C₂₂-double bond compounds, which can be recognized from ¹³C NMR spectra by different chemical shifts of C₂₂-position carbon atom. All the important intermediates were identified by ¹H NMR,¹³C NMR and ESI-MS and the melting points and optical rotations of the solid materials were also measured.In addition, the types of the glycosides were confirmed by calculating the vicinal coupling constants in ¹H NMR spectra and the mechanism was also...