C9 taxane derivatives

A tetracylic taxane having the formula ##STR27## wherein R.sub.1 is H, --OH, protected hydroxy, or --OCOR.sub.8,

• R.sub.4 is H, --OH or protected hydroxy;
• R.sub.5 is H or R.sub.9 CO--,
• R.sub.6 is H or R.sub.10 CO--,
• R.sub.7 is H or a hydroxy protecting group, and
• R.sub.8, R.sub.9, and R.sub.10 are independently H, C.sub.1 -C.sub.6 alkyl, C.sub.2 -C.sub.6 alkenyl, C.sub.2 -C.sub.6 alkynyl, moncyclic aryl, or monocyclic heteroaryl.