| abstract |
Compound of formula (I) ** Formula ** in which R is isobutyl in C-3 or C-4; R 'is hydrogen at C-3 or C-4 and the link between C-3 and C-4, together with the dotted line, represents a double bond; or R 'is -CH2- and, together with C-3 and C-4, represents a cyclopropane ring, and the link between C-3 and C-4, together with the dotted line, represents a single bond; R1 and R2 represent, independently of each other, a group selected from hydrogen, methyl and ethyl; R3 is selected from methyl and ethyl; and R4 is hydroxyl and R5 is hydrogen; or R1, R2 and R3 represent, independently of one another, a group selected from hydrogen, methyl and ethyl, in which at least one is not hydrogen; and R4 and R5, together with the carbon atom to which they are attached, represent a carbonyl. |