| abstract |
A process for the preparation of the compounds of general formula (I) n n n in which n R 1 is H or OH; n R 2 is H, α-OH, or β-OH; and n R 3 is a straight or branched C 1 -C 4 alkyl group or a benzyl group, n comprising the reduction of compounds of formula (III) n n n wherein R 1 , R 2 and R 3 have the same meanings as in formula I, in the presence of sodium borohydride. |