A compound of formula I: ** Formula ** where (i) X is ** Formula ** and (a) Ra and Rb are H； R2 is H； and R7 is selected from -CH2CF2CH3, -CH2CF2CF3, - (CH2) 5CH3, - (CH2) 6CH3, and ** Formula ** or R2 is -C1-6 alkyl or -C (O) -C1-6 alkyl, and R7 is H； or (b) R3 is selected from -CH3, -OCH3, and Cl and Rb is H； or R3 is selected from H, -CH3, Cl, and F, and Rb is Cl； or Ra is H and Rb is selected from -CH3 and -CN； R2 is selected from H, -C1-6 alkyl, - (CH2) 2-3ORe, and - (CH2) 2-3NReRe； and R7 is selected from H, -C1-6 alkyl, - [(CH2) 2O] 1-3CH3, -CHRcOC (O) -C1-4 alkyl, - CH2OC (O) CHRd-NH2, -CH2OC (O) CHRd -NHC (O) O-C1-6 alkyl, -CHRcOC (O) O-C2-4 alkyl, -CHRcOC (O) Ocyclohexyl, -CH2CH (NH2) C (O) OCH3, -C2-4-N alkylene CH3) 2, -C0-6 alkylenemorpholinyl, and ** Formula ** or (c) R3 is H and Rb is F； or R3 is F and Rb is H； R2 is selected from H, -C1-6 alkyl, - (CH2) 2-3ORe, and - (CH2) 2-3NReRe； and R7 is selected from -C1-6 alkyl, - [(CH2) 2O] 1-3CH3, -CHRcOC (O) -C1-4 alkyl, -CH2OC (O) CHR-NH2, -CH2OC (O) CHRd-NHC (O) O-C1-6 alkyl, -CHRcOC (O) O-C2-4 alkyl, -CHRcOC (O) O30 cyclohexyl, -CH2CH (NH2) C (O) OCH3, -C2-4-N alkylene (CH3 ) 2, -C0-6 alkylenemorpholinyl, and ** Formula ** or (ii) X is ** Formula ** and (a) Ra is Cl and Rb is H； or Ra is H and Rb is selected from Cl, F, -CH3, and -CN； or Ra is F and Rb is Cl； R2 is selected from H, -C1-6 alkyl, - (CH2) 2-3ORe, and - (CH2) 2-3NReRe； R4 is selected from -OH, -OCH3, -OCH2CH3, and -C1-4 alkyl； and R7 is selected from H, -C1-6 alkyl, - [(CH2) 2O] 1-3CH3, -CHRcOC (O) -C1-4 alkyl, -CH2OC (O) CHRd-NH2, -CH2OC (O) CHRd -NHC (O) O-C1-6 alkyl, -CHRcOC (O) O-C2-4 alkyl, -CHRcOC (O) Ocyclohexyl, -CH2CH (NH2) C (O) OCH3, -C2-4-N alkylene CH3) 2, -C0-6 alkylenemorpholinyl, and ** Formula ** (b) Ra is F and Rb is H； R2 is H； R4 is -OH； and R7 is selected from -C1-6 alkyl, - [(CH2) 2O] 1-3CH3, - CHRcOC (O) -C1-4 alkyl, -CH2OC (O) CHRd-NH2, -CH2OC (O) CHRd-NHC (O) O-C1-6 alkyl, -CHRcOC (O) C2-4alkyl, -CHRcOC (O) O-cyclohe
