Purpnigenin (I), C₂₁H₃₂O₄, is positive to the Liebermann reaction and has three C-CH₃ groups. It was assumed to have a pregnenolone skeleton from the presence of an absorption for 20-ketone in its infrared spectrum and formation of acetic acid and propionic acid by the decomposition of the Wolff-Kishner reduction product (II). (I) forms a diaceate and a monoxime, and the infrared spectrum of the diacetate contains the absorption of a hydroxyl. Consequently, three of the four oxygens in (I) would belong to hydroxyls and the remaining one to the carbonyl. Oppenauer oxidation of (I) gives a 4-en-3-one compound (III) and (I) is therefore assumed as 5-en-3-ol. Since (I) consumes periodic acid and chromic acid oxidation of (III) produces five-membered ring ketone (IV), the two hydroxyls, other than that in 3-position, are likely to be secondary and tertiary, and in adjacent positions in the D-ring. In spite of the Oppenauer oxidation, (III) retains the five-membered D-ring and, therefore, (I) is likely to be 14, 15-diol, rather than 16, 17-diol. From these experimental evidences, 3, 14, 15-trihydroxypregn-5-en-20-one is proposed as the structure for (I).