
TY  - JOUR
A1  - Watson, TR 
A1  - Wright, SE 
T1  - The cardiac glycosides of <I>Gomphocarpusf ruticosus</I> R.Br. I. Afroside
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1956
VL  - 9
IS  - 4
SP  - 497
EP  - 511
KW  - 
UR  - https://doi.org/10.1071/CH9560497 
N2  - Afroside, C29H42O9, is a new cardiac glycoside which has been obtained from Gomphocarpus fruticosus R.Br. It contains a carbonyl (aldehyde) group at C10, and a secondary hydroxyl group in the nucleus, which has been placed provisionally at position C11. On the basis of the available evidence, afroside appears to consist of a mixture of the isomeric free aldehyde and the 19-11 cyclic hemiacetal forms. Of these substances, the cyclic hemiacetal form is the only one which has been isolated in pure condition (afroside B). Acetylation of afroside produced a triacetate, C35H46O12.H2O, which is identical with that obtained by the acetylation of afroside B. Reduction of afroside with sodium borohydride produces afrosidol, C29H44O9, which shows no evidence for a carbonyl group at C10. Hydrolysis of afroside produces &#945;-anhydroafrogenin, C23H28-30O5.H2O, which forms a monoacetate, C25H32O7.H2O. The infra-red spectra of these compounds show the presence of a saturated &#947;-lactone ring in the structure of the nucleus, besides the normal &#916;&#945;-&#946;-&#947;-lactone ring at C17 (1786, 1755, 1633 cm-1). Acetyl-&#945;-anhydroafrogenin also shows an intense absorption band of simple structure at 1238 cm-1, which indicates an equatorially orientated acetyl group at C3. As all the naturally occurring cardiac aglycones of known structure have a &#946;-orientated hydroxyl group at C3, for the substituent in this position to be equatorial, the A/B ring junction is probably trans.   Hydrolysis of afrosidol produces &#945;-anhydroafrogenol, C23H32O5.H2O, which forms a diacetate, C27H36O7.H2O. The infra-red spectrum of &#945;-anhydroafrogenol shows no evidence of the saturated y-lactone ring which is present in the structure of &#945;-anhydroafrogenin. 
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