| abstract |
A process for the preparation of the compounds of general formula (I) in which R1 is H or OH; R2 is H, α-OH, or β-OH; and R3 is a straight or branched C1-C4 alkyl group or a benzyl group, comprising the reduction of compounds of formula (III) wherein R1, R2 and R3 have the same meanings as in formula (I), in the presence of sodium borohydride. |