ISSN:
0170-2041
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Preparation of Unsaturated Lactones in the Steroid Series. XII1). - Synthesis of Novel 4,5-Didehydro-14,15β-epoxybufadienolides and their L-Rhamnopyranosides*)14,15β-Epoxy-3β-hydroxy-14β-bufa-4,20,22-trienolide (4), structurally related to scillarenin, was obtained by addition of hypobromous acid to the 14(15)-double bond of synthetically accessible 14-anhydroscillarenone (1), subsequent transformation of the resulting 15α,14β-bromohydrin to the 14,15β-epoxide 3, and reduction of the 3-oxo to the 3β-hydroxy group. - The 3-α-L-rhamnopyranoside 11 of 4 was obtained from proscillaridin A (6) by first protecting the sugar hydroxy groups as acetates (6 → 7) and then dehydrating the 14β-hydroxy group to the 14(15) double bond (7 → 8). Conversion of 8 to the bromohydrin or iodohydrin led subsequently to the 14,15β-epoxy analog of proscillaridin A 10, acetylated in the sugar moiety. Saponification of the acetate protecting groups gave 14,15β-epoxy-3β-hydroxy-14β-bufa-4,20,22-trienolide 3-α-L-rhamnopyranoside (11), which was cleaved to the aglycon 4 with KIO4. Compound 11 shows an interesting spectrum of pharmacological activity which is briefly presented.
Notes:
Durch Addition von hypobromiger Säure an die 14(15)-Doppelbindung des synthetisch zugänglichen 14-Anhydroscillarenons (1), Umwandlung der 15α,14β-Bromhydringruppe zum 14,15β-Epoxid 3 und Reduktion der 3-Oxo- zur 3β-Hydroxygruppe wird das dem Scillarenin strukturell ver-wandte 14,15β-Epoxy-3β-hydroxy-14β-bufa-4,20,22-trienolid (4) erhalten. - Zur Synthese des 3-α-L-Rhamnopyranosids 11 von 4 wird, ausgehend vom Proscillaridin A (6), nach Schutz der Zucker-Hydroxygruppen als Acetate (6 → 7), Dehydratisierung der 14β-Hydroxygruppe zur 14(15)-Doppelbindung (7 → 8) über das Bromhydrin 9 bzw. das Iodhydrin das im Zuckeranteil acetylierte 14,15β-Epoxy-Analoge 10 des Proscillaridins A erhalten. Das daraus nach Verseifung der Acetat-Schutzgruppen resultierende 14,15β-Epoxy-3β-hydroxy-14β-bufa-4,20,22-trienolid-3-(α-L-rhamnopyranosid) (11), das mit KIO4 zum Aglycon 4 abgebaut werden kann, zeigt ein interessantes pharmakologisches Wirkungsspektrum, das kurz vorgestellt wird.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.198219820216
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