A compound having a structural formula (IIa): ** Formula ** or a salt or solvate thereof, in which: X is -CH2-； R1 is -C (O) NR5R6； R2 is hydrogen or alkyl optionally substituted with one or more R14 substituents； -NR5R6 is selected from the group consisting of: ** Formula ** Z1 is N； Z2 is CR12 or N； R12 is selected from hydrogen or alkyl optionally substituted with one or more R14 substituents； n is an integer from 0 to 5； m is 0； and each R11 is independently selected from the group consisting of acyl optionally substituted with one or more substituents R14, alkoxycarbonyl optionally substituted with one or more substituents R14, aryloxycarbonyl optionally substituted with one or more substituents R15, -C (O) NR11AR11B, ethyl , propyl, butyl, each optionally substituted with one or more R14 substituents, aryl optionally substituted with one or more R15 substituents, arylalkyl optionally substituted with one or more R14 substituents, cycloheteroalkyl optionally substituted with one or more R14 substituents, heteroaryl optionally substituted with one or more R15 substituents, heteroarylalkyl optionally substituted with one or more R14 substituents, heteroalkyl optionally substituted with one or more R14 substituents, wherein R11A and R11B are independently hydrogen, alkyl optionally substituted with one or moreUn compuesto que tiene una formula estructural (IIa):**Fórmula** o una sal o un solvato del mismo, en la que: X es -CH2-； R1 es -C(O)NR5R6； R2 es hidrogeno o alquilo opcionalmente sustituido con uno o mas sustituyentes R14； -NR5R6 se selecciona entre el grupo que consiste en:**Fórmula** Z1 es N； Z2 es CR12 o N； R12 se selecciona entre hidrogeno o alquilo opcionalmente sustituido con uno o mas sustituyentes R14； n es un numero entero de 0 a 5； m es 0； y cada R11 se selecciona independientemente entre el grupo que consiste en acilo opcionalmente sustituido con uno o mas sustituyentes R14, alcoxicarbonilo opcionalmente sustituido con uno o mas sustituyentes R14,
