Patent ID: 7390898

Claim:
A compound represented by formula (I): wherein: R 1 is H, an electron withdrawing group, or an electron donating group; R 1 ′ and R 1 ″ are the same or different, and are H, an electron withdrawing group, or an electron donating group; R 2 is H; R 3 is alkenyl having from 2 to 10 carbon atoms, cycloalkenyl having from 3 to 10 carbon atoms, or heterocyclic; R 4 is alkyl having from 1 to 10 carbon atoms, alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, aryl, heterocyclic, —OC(CH 3 ) 3 , or together with the —CONH— group at the C-3′ position, a carbamate formed from any of an alkyl having from 1 to 10 carbon atoms, alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, aryl, or heterocyclic and an oxygen atom; R 5 is a reactive group that forms a disulfide link, a thioether link, an acid labile link, a photolabile link, a peptidase labile link or an esterase labile link between the oxygen atom at the C-7 position and a cell binding agent; and R 6 is H, or together with the oxygen atom at the C-2′ position, a heterocyclic or aryl ether, a heterocyclic or aryl ester, a heterocyclic or aryl carbamate, a linear, branched or cyclic alkyl ester group having from 1 to 10 carbon atoms in the alkyl, a linear, branched or cyclic alkenyl ester group having from 2 to 10 carbon atoms in the alkenyl, a linear, branched, or cyclic alkyl ether group having from 1 to 10 carbon atoms, a linear, branched, or cyclic alkenyl ether group having from 2 to 10 carbon atoms, a carbamate group of the formula —OCOX, wherein X is a nitrogen-containing heterocyclic group, or a carbamate of the formula —OCONR 10 R 11 , wherein R 10 and R 11 are the same or different and are H, linear, branched or cyclic alkyl having from 1 to 10 carbon atoms, or simple or substituted aryl having from 6 to 10 carbon atoms, provided that when R 3 is —CH═C(CH 3 ) 2 , R 4 is not an aryl or —OC(CH 3 ) 3 .