Baccatin derivatives and processes for preparing the same

Abstract

A compound represented by the formula [I]: ##STR1## wherein R.sup.3 represents a lower alkanoyl group; R.sup.4 represents a substituted or unsubstituted benzoyl group; ring A represents a substituted or unsubstituted cyclopropane ring; X represents a single bond or a group represented by --O--, --S-- or --NH--; R represents a substituted or unsubstituted lower alkyl group (wherein said lower alkyl group may have a cycloalkyl moiety), a substituted or unsubstituted aryl group or a substituted or unsubstituted aromatic heterocyclic group; E represents hydrogen atom or a group represented by --CO(CH.sub.2).sub.n ZY; Y represents a residue obtained from an amino acid or a dipeptide by removing hydroxyl group in one carboxyl group therefrom (wherein amino group existing in said residue may be protected, and carboxyl group existing in said residue may be esterified or amidated); Z represents a group represented by the formula of --O-- or --NH--; and n represents 1, 2, 3, 4, 5 or 6, or a pharmaceutically acceptable salt thereof. Said compounds have excellent antitumor activity so that they are useful in the prophylaxis or treatment of a wide range of tumors such as breast cancer, ovary cancer, lung cancer, malignant melanoma and the like.