Certain substituted taxanes and pharmaceutical compositions containing them

A taxane derivative of the formula ##STR1## wherein R.sub.1 and R.sub.3 are independently selected from the group comprising phenyl, naphthalene, C.sub.6 H.sub.5 CHCH--, and ##STR2## provided, however, R.sub.1 and R.sub.3 are not both phenyl; PA0 Q is CH.sub.3 --, (CH.sub.3).sub.3 C--, CH.sub.3 O--, Cl, Br, F, NO.sub.2, ##STR3## Z is --OT.sub.1, T.sub.1 is hydrogen, hydroxyl protecting group, or --COT.sub.2, PA0 T.sub.2 is H, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkenyl, C.sub.1 -C.sub.6 alkynyl or monocylic aryl, PA0 Ac is acetyl, and PA0 E.sub.1 and E.sub.2 are independently selected from hydrogen and functional groups which increase the water solubility of the taxane derivative are useful as antitumor agents.