| abstract |
A process for the preparation of antibiotics of the anthracycline class of formula (A), wherein R 1 is hydrogen, OH, or OCOR 2 , wherein R 2 is a C 1 -C 4 -alkyl group; which comprises the epimerization of the 4' hydroxy group of the daunosamine residue by nucleophilic substitution of a triflate group with a carboxylate, which epimerization is carried out on the whole molecule with the hydroxy groups being protected, and subsequent transformation into the final product. |