Process for preparing taxane derivatives, new derivatives obtained and pharmaceutical compositions containing them

Process for preparing taxane derivatives of general formula:

• ##STR17## in which R represents a t-butoxy or phenyl radical, R.sub.1 represents a hydrogen atom or an acetyl radical and Ar represents an aryl radical, characterized in that:
• a) an oxazolidine derivative of general formula:
• ##STR18## in which Ar is defined as above, Boc represents a t-butoxycarbonyl radical and R.sub.6 and R.sub.7, which may be identical or different, represent an alkyl radical containing 1 to 4 carbon atoms, optionally substituted with one or more aryl radicals, or an aryl, or alternatively R.sub.6 and R.sub.7, together with the carbon atom to which they are linked, form a 4- to 7-membered ring, is condensed with a taxane derivative of general formula:
• ##STR19## in which R'.sub.1 represents an acetyl radical or a group protecting the hydroxyl function and R.sub.2 represents a group protecting the hydroxyl function, to obtain a product of general formula:
• ##STR20## in which Ar, R'.sub.1, R.sub.2, R.sub.6 and R.sub.7 are defined as above, b) the product is treated in an acid medium, under conditions which have no effect on R'.sub.1 and R.sub.2, to obtain the product of general formula:
• ##STR21## in which R'.sub.1 and R.sub.2 are defined as above, c) the product is treated with a suitable reagent enabling a t-butoxycarbonyl or benzoyl radical to be introduced on the amino function to obtain a product of general formula:
• ##STR22## d) the protective groups R'.sub.1 and R.sub.2 are replaced by hydrogen atoms, and then
• e) the product obtained is isolated and, purified.