A facile approach to diosgenin and furostan type saponins bearing a 3β-chacotriose moiety
| Autor: | Helena Gybäck, René Suhr, Joachim Thiem, Stefan Oscarson, Martina Lahmann, Per J. Garegg |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
chemistry.chemical_classification
Magnetic Resonance Spectroscopy Double bond Rhamnose Stereochemistry Organic Chemistry Acetal Antineoplastic Agents General Medicine Nuclear magnetic resonance spectroscopy Diosgenin Saponins Biochemistry Analytical Chemistry Silyl ether chemistry.chemical_compound chemistry Moiety Reactivity (chemistry) Tropanes |
| Zdroj: | Carbohydrate Research. 337:2153-2159 |
| ISSN: | 0008-6215 |
| DOI: | 10.1016/s0008-6215(02)00275-6 |
| Popis: | Combination of a one-pot coupling technique and the use of benzyl ethers as permanent protecting groups offered a short and simple route to dioscin-type saponins. This strategy in combination with a mild reductive opening procedure of the spiroketal function in diosgenin also offered a convenient approach to bidesmosidic furostan type saponins. Me(3)N.BH(3)/AlCl(3) promoted acetal opening of 3-O-TBDMS-protected diosgenin gave the 26-OH acceptor 9 into which a benzylated beta-glucose moiety was introduced by a S(N)2-type imidate coupling. After cleavage of the silyl ether, the 3beta-O-glucose and the 4-O-linked rhamnose of the chacotriose unit were introduced by a NIS/AgOTf-promoted one-pot coupling sequence utilising thioglycoside donors and their different reactivity in different solvents. After removal of a benzoyl group, the same coupling conditions were also used for the coupling of the second 2-O-linked rhamnose unit. The target substance was obtained after cleavage of the protecting benzyl ethers under Birch-type conditions, which did not affect the double bond in the steroid skeleton. |
| Databáze: | OpenAIRE |
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