METHOD OF OBTAINING DERIVATIVES OF VINBLASTIN OR THEIR EPIMERS

The invention relates to new cytostatic compound, process for their preparation and pharmaceutical compositions containing them. More particularly, there are provided new compounds of the general formula /I/ in which R4 is beta -hydroxyl and R3 is alpha -ethyl; or R4 is hydrogen and R3 is beta -ethyl; R'' is a straight chained alkyl having from 1 to 10 carbon atoms, or a branched chained alkyl having from 3 to 10 carbon atoms, in which groups the carbon atom attached to the >Na-CH2-O- group has a primary or secondary configuration or an alkenyl or alkinyl having from 3 to 6 carbon atoms, or an aralkyl having from 1 to 3 carbon atoms in the alkyl moiety; R1 is methoxy and R2 is acetyl, provided that if R3 is alpha -ethyl and R4 beta -hydroxyl, R4 is other than ethyl. These compounds and N-desmethyl-N-(ethoxymethyl)-vinblastine can be prepared according to the invention by transetherification of compounds of the compounds of the general formula /II/ with a large excess of alcohols of the general formula R''-OH [III] Pharmaceutical compositions containing compounds of the general formula [I] as active ingredients are also within the scope of invention.