-Bu, ???(CH2)2NH2 or ???(CH2)3NH2), ???(CH2)n-aryl (e.g. benzyl optionally substituted by a halogen atom, such as a fluorine atom), ???(CH2)n-heterocyclyl (e.g. ???CH2-dioxaolanyl (optionally substituted by one or more C1-6 alkyl (e.g. methyl) groups), ???CH2-tetrahydrofuranyl or ???CH2-piperidinyl) or haloC1-6 alkyl (e.g. ???(CH2)2???F, ???CH2???CH???F2???CH(Me)-CF3 or ???CH2???CF3).In one embodi