Patent ID: 8791098

Claim:
A pre-tubulysin compound having the formula I or II wherein R 1 is a branched or linear, saturated or unsaturated C 1-6 alkyl group which may carry 1 to 3 substituents independently selected from phenyl, halogen, C 1-3 -alkoxy and phenoxy; R 2 is a branched or linear, saturated or unsaturated C 1-16 alkyl group; R 3 is H or a branched or linear, saturated or unsaturated C 1-6 alkyl group which may carry 1 to 3 substituents independently selected from phenyl, halogen, C 1-3 -alkoxy and phenoxy; Ar is phenyl or naphthyl group which may carry 1 to 3 substituents independently selected from C 1-3 -alkyl, C 1-3 -alkenyl, halogen, C 1-3 -alkoxy and C 1-3 -alkenoxy; n is an integer of 0 to 2; and denotes a single or double bond, or an ester of the C-terminal carboxy group with a monohydric or polyhydric alcohol and/or a pharmaceutically acceptable salt thereof.