Triterpenes of the friedelane series. VI. The structure of Friedelan-y-al

Abstract

The preparation of a number of compounds of the friedelane series having an oxygen function at C 24 is described. Mass spectrometric considerations indicate that friedelan-y-al is either friedelan-24-al or friedelan-25-al. A comparison shows that the C 24 derivatives are not identical with the natural products. The natural product must therefore have an oxygen function at C 25. Positive chemical proof of this assignment has been obtained by conversion of friedelane-3,x-dion- 25-oic acid into 5β-hydroxyalnusane-3,x-dion-25-oic acid 5(25)-lactone.