New taxoids of general formula (I), their preparation, and pharmaceutical compounds containing them. In general formula (I), for example, Ar represents an aryl radical, R represents an alkoxyacetyl radical, R1 represents a benzoyl radical or a radical of formula R2—O—CO— in which R2 represents an optionally substituted alkyl radical, an alkenyl, alkynyl, cycloalkyl, cycloalkenyl, bicycloalkyl, phenyl or heterocyclyl radical. The new products of general formula (I) have a remarkable antitumor activity.