A compound of formula I, or a pharmaceutically acceptable salt or ester thereof, wherein R1 is selected from: aryl； heteroaryl； &mdash；NHR3； fused aryl-C4-7-heterocycloalkyl； &mdash；CONR4R5； &mdash；NHCOR6； &mdash；C3-7-cycloalkyl； &mdash；O&mdash；C3-7-cycloalkyl； &mdash；NR3R6； and optionally substituted &mdash；C1-6 alkyl； wherein said aryl, heteroaryl, fused aryl-C4-7-heterocycloalkyl and C4-7-heterocycloalkyl are each optionally substituted； R2 is selected from hydrogen, aryl, C1-6-alkyl, C2-6-alkenyl, C3-7-cycloalkyl, heteroaryl, C4-7 heterocycloalkyl and halogen, wherein said C1-6-alkyl, C2-6-alkenyl, aryl, heteroaryl and C4-7-heterocycloalkyl are each optionally substituted； R3 is selected from aryl, heteroaryl, C4-7-heterocycloalkyl, C3-7-cycloalkyl, fused aryl-C4-7-heterocycloalkyl and C1-6-alkyl, each of which is optionally substituted； R4 and R5 are each independently hydrogen, or optionally substituted C3-7-cycloalkyl, aryl, heteroaryl, C1-6-alkyl or C3-6-heterocycloalkyl； or R4 and R5 together with the N to which they are attached form a C3-6-heterocycloalkyl ring； each R6 is independently selected from C1-6-alkyl, C3-7 cycloalkyl, C4-7-heterocycloalkyl, aryl and heteroaryl, each of which is optionally substituted each R7 is selected from hydrogen, optionally substituted C1-6-alkyl and C3-7-cycloalkyl； each of R8 and R9 is independently hydrogen or optionally substituted C1-6-alkyl； or R8 and R9 together with the N to which they are attached form a C4-6-heterocycloalkyl； each R10 is selected from C3-7-cycloalkyl and optionally substituted C1-6-alkyl； each R11 is independently selected from C1-6-alkyl, C3-7-cycloalkyl, C1-6 alkyl-C3-7-cycloalkyl, C4-7-heterocycloalkyl, aryl and heteroaryl, each of which is optionally substituted； A is selected from halogen, &mdash；NR4SO2R5, &mdash；CN, &mdash；OR6, &mdash；NR4R5, &mdash；NR7R11, hydroxyl, &mdash；CF3, &mdash；CONR4R5, &mdash；NR4COR5, &mdash；NR7(CO)NR4R5, &mdash；NO2, &mdash；CO2H, &mdash；CO2R6, &mdash；SO2R6, &mdash；S
