| abstract |
A compound with the formula I, wherein R 2 is of formula II, where A is a C 5-7 aryl group, X is selected from the group consisting of: OH, SH, CO 2 H, COH, N═C═O, NHNH 2 , CONHNH 2 , (III), (IV), and NHR N , wherein R N is selected from H and C 1-4 alkyl, and either: (i) Q 1 is a single bond, and Q 2 is selected from a single bond and —Z—(CH 2 ) n —, where Z is selected from a single bond, O, S and NH and n is from 1 to 3; or (ii) Q 1 is —CH═CH—, and Q 2 is a single bond; and its conjugates. |