Monoacetylation of 11b,17a-dihydroxy-4-pregnen-3,20-dione (I) at position 11 with acetic anhydride and pyridine provided acetate (II). Ketalization of both ketonic groups with ethylene glycol was accompanied by doble bond migration to position 5 to give (III), which was then converted to epoxide (IV) on treatment with m-chloroperbenzoic acid. Grignard reaction of epoxide (IV) with methylmagnesium bromide gave the 5a-hydroxy-6b-methylpregnene (V) with concomitant cleavage of the acetyl group. Smooth ketal hydrolysis with potassium bisulfate in aqueous acetone provided diketone (VI) without dehydration of the 11b-hydroxy group, and further treatment with NaOH in aqueous methanol effected crotonization of 5b-hydroxyl to the unsaturated ketone (VII). Reaction with 70% hydrogen fluoride in pyridine provided the 9a-fluorinated compound (VIII), together with some dehydrated product. A new sequence of ketalization with ethylene glycol and further hydrolysis of the resulting ketal (IX) produced epimerization of the 6-methyl group. The resulting compound (X) was finally acetylated by the mixed anhydride method by treatment with acetic acid and trifluoroacetic anhydride.