A compound of formula (I): in which: Y is a group of formula - (CR9R10) n-； X is selected from the group consisting of -C (>； = O) -, -OC (>； = O) -, -NHC (>； = O) -, - (CR11R12) and -S (>； = O) 2-； Z is a group of formula - (CR13R14) q-； R1 is selected from the group consisting of H, optionally substituted C1-C12 alkyl, optionally substituted C2-C12 alkenyl, optionally substituted C2-C12 alkynyl, optionally substituted C1-C12 heteroaryl, optionally substituted C3-C12 cycloalkyl, optionally substituted C2-C12 heterocycloalkyl , optionally substituted C6-C18 aryl and optionally substituted C1-C18 heteroaryl； R2 and R3 are each independently selected from the group consisting of H, optionally substituted C1-C12 alkyl, optionally substituted C2-C12 alkenyl, optionally substituted C2-C12 alkynyl, optionally substituted C1-C12 heteroaryl, optionally substituted C3-C12 cycloalkyl, heterocycloalkyl Optionally substituted C2-C12, optionally substituted C6-C18 aryl and optionally substituted C1-C18 heteroaryl； R4a is selected from the group consisting of H, optionally substituted C1-C12 alkyl, optionally substituted C2-C12 alkenyl, optionally substituted C2-C12 alkynyl, heteroaryl Optionally substituted C1-C12, optionally substituted C3-C12 cycloalkyl, optionally substituted C2-C12 heterocycloalkyl, optionally substituted C6-C18 aryl, optionally substituted C1-C18 heteroaryl, C (>； = O) R15, C (>； = O) NR15R16, C (>； = O) OR15, SO2R15, C (>； = O) H, -C (>； = NR15) -NR16R17 and OR15, R4b is selected from the group consisting of H, C1-C12 alkyl optionally and substituted, optionally substituted C2-C12 alkenyl, optionally substituted C2-C12 alkynyl, optionally substituted C1-C12 heteroaryl, optionally substituted C3-C12 cycloalkyl, optionally substituted C2-C12 heterocycloalkyl, optionally substituted C6-C18 aryl, optionally substituted C1-C18 heteroaryl C (>； = O) R15, C (>； = O) NR15R16, C (>； = O) OR15, oR4a and R4b, when taken together with the nitro
