Synthesis Of Furostanol Saponins

Furostanol saponins are complex triterpenoid and steroid glycoconjugates with a variety of biological activities, which act as active ingredients of the medicinal plants. However, due to the similar structure and a low content, it makes particularly difficulty by isolating and extracting saponins obtained from natural plant plants for a large number of single component, thereby limiting their biological function and the mechanism of action of the study.In recent years, as people gradually increased attention on the the furostanol saponins structure and function, as well as the rapid development of carbohydrate chemistry, chemical synthesis has become one of the effective means to obtain high-quality furostanol saponins. This are six furostanol saponins with good bioactivities in the dissertation.Through the analysis of these six steroidal saponins structure,we use the tactic of linear strategies glycosylation. Diosgenin as a starting material, under the conditions of the Lewis acid boron trifluoride etherate, the E, F ring are opened simultaneously to give Compound 3-24. Then compound 3-24 as glycosyl acceptors, the compound 3-04 as the glycosyl donor, glycosylation occurs in the 26-OH of the compound 3-24 obtained 3-25 at the promotion of trimethylsilyl trifluoromethanesulfonic acid (TMSOTf). Finally deprotection of the corresponding protecting groups to give Methyl Funlioside B; Reference to the above-described method, compound 3-28 and compound 3-29 were obtained in a 65% and 20% yied, respectively. After two steps of protective group modulations, compound 3-31 was gived.Under the conditions of TMSOTf and NIS, the glycosylation reaction occurs to give compound 3-38 with compound 3-31 as glycosyl acceptors, the compound 3-37 as the glycosyl donor. Using the NH2NH2·H2O, we remove the Lev-of compound 3-38 and obtain the compound 3-39. Then compound 3-39 as glycosyl acceptors, L-rhamnopyranosyl trichloroacetimidate 3-08 as the glycosyl donor, glycosylation occured and compound 3-40 was obtained at the promotion of TMSOTf. With modifying protecting groups again, the coupling reactions acceptor 3-40 with L-rhamnopyranosyl trichloroacetimidate 3-08、 D-xylopyranosyl tricholoracetimidate 3-13、L-arabinopyranosyl tricholoracetimidate 3-18、 L-arabinofuranosyl tricholoracetimid ate 3-22 respectively were carried out. Finally the target products were synthesized by deprotections with base (LiOH).The structures of all target products were characterzed by 1H NMR, 13C NMR, HRMS and optical rotation analysis.