The oxidation of pradimicin FA-2 (I) with 3,5-di-tert-butyl-1,2-benzoquinone (DBBQ) according to Corey's method gives the corresponding imine (II), which by hydrolysis with formic acid is converted into the 4'-deamino-4'-oxo derivative (III). Finally, this compound is reduced with NaBH4 in water yielding the mixture of the 4'-hydroxy epimers, which is separated by HPLC chromatography.