A compound of formula I or a pharmaceutically acceptable salt thereof for use in treating cancer or an immunological or neurological disease, wherein formula is: wherein: L represents CH 2 CH 2; one X represents S and the other X represents CH=CH, wherein any hydrogen atom of a CH unit may be replaced by (C 1-6)alkyl; Y, independently for each occurrence, represents H or CH 2 O R 7; R 7, independently for each occurrence, represents H or substituted or unsubstituted (C 1-6)alkyl, (C 1-6)alkoxy, amino(C 1-6)a l kyl, (C 1-6)alkylamino(C 1-6)alkyl, 3-10 membered heterocyclyl(C 1-6)alkyl, or 3-10 membered heterocyclyl(C 1-6)alkoxy; Z represents R 3; R 1 and R 2 each independently represent H; R 3, independently for each occurrence, represents: (a) substituted or unsubstituted 5-7 membered aryl(C 1-6)alkyl, (C 3-8)cycloalkyl, heterocycloalkyl, or 5-7 membered heteroaryl(C 1-6)alkyl; or (b) C(R 8)(R 9)(R 10); R 8 represents substituted or unsubstituted 5-7 membered aryl, 5-7 membered aryl(C 1-6)alkyl, 5-7 membered heteroaryl, or 5-7 membered heteroaryl(C 1-6)alkyl; R 9 represents H; and R 10 represents hydroxyl, hydroxy(C 1-6)alkyl, (C 1-6)alkoxy, or (C 1-6)alkoxy(C 1-6)alkyl; wherein, where indicated, (C 1 -C 6)alkyl, hydroxy(C 1 -C 6)alkyl, amino(C 1 -C 6)alkyl, (C 1 -C 6)alkylamino(C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, (C 1 -C 6)alkoxy(C 1 -C 6)alkyl, 5-7 membered aryl, 5-7 membered aryl(C 1 -C 6)alkyl, (C 3 -C 8)cycloalkyl, 3-10 membered heterocyclyl, 3-10 membered heterocyclyl(C 1 -C 6)alkyl, 3-10 membered heterocyclyl(C 1 -C 6)alkoxy, 5-7 membered heteroaryl, or 5-7 membered heteroaryl(C 1 -C 6)alkyl is optionally substituted with one or more substituents selected from halogen, hydroxyl, carboxyl, (C 1 -C 6)alkoxycarbonyl, formyl, acyl, thioester, thioacetate, thioformate, (C 1 -C 6)alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino, amido, amidine, imine, cyano, nitro, azido, sulfhydryl, (C 1 -C 6)alkylthio, sulfate, sulfonate, sulfamoyl, sulfonamido, sulfonyl, 3-10 membered heterocyclyl, (C 5 -C 7)aryl(C 1 -C 6)alkyl, (C 5 -C 7)aryl, and 5-7 membered heteroaryl. L represents CH 2 CH 2; one X represents S and the other X represents CH=CH, wherein any hydrogen atom of a CH unit may be replaced by (C 1-6)alkyl; Y, independently for each occurrence, represents H or CH 2 O R 7; R 7, independently for each occurrence, represents H or substituted or unsubstituted (C 1-6)alkyl, (C 1-6)alkoxy, amino(C 1-6)a l kyl, (C 1-6)alkylamino(C 1-6)alkyl, 3-10 membered heterocyclyl(C 1-6)alkyl, or 3-10 membered heterocyclyl(C 1-6)alkoxy; Z represents R 3; R 1 and R 2 each independently represent H; R 3, independently for each occurrence, represents: (a) substituted or unsubstituted 5-7 membered aryl(C 1-6)alkyl, (C 3-8)cycloalkyl, heterocycloalkyl, or 5-7 membered heteroaryl(C 1-6)alkyl; or (b) C(R 8)(R 9)(R 10); (a) substituted or unsubstituted 5-7 membered aryl(C 1-6)alkyl, (C 3-8)cycloalkyl, heterocycloalkyl, or 5-7 membered heteroaryl(C 1-6)alkyl; or (b) C(R 8)(R 9)(R 10); R 8 represents substituted or unsubstituted 5-7 membered aryl, 5-7 membered aryl(C 1-6)alkyl, 5-7 membered heteroaryl, or 5-7 membered heteroaryl(C 1-6)alkyl; R 9 represents H; and R 10 represents hydroxyl, hydroxy(C 1-6)alkyl, (C 1-6)alkoxy, or (C 1-6)alkoxy(C 1-6)alkyl; wherein, where indicated, (C 1 -C 6)alkyl, hydroxy(C 1 -C 6)alkyl, amino(C 1 -C 6)alkyl, (C 1 -C 6)alkylamino(C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, (C 1 -C 6)alkoxy(C 1 -C 6)alkyl, 5-7 membered aryl, 5-7 membered aryl(C 1 -C 6)alkyl, (C 3 -C 8)cycloalkyl, 3-10 membered heterocyclyl, 3-10 membered heterocyclyl(C 1 -C 6)alkyl, 3-10 membered heterocyclyl(C 1 -C 6)alkoxy, 5-7 membered heteroaryl, or 5-7 membered heteroaryl(C 1 -C 6)alkyl is optionally substituted with one or more substituents selected from halogen, hydroxyl, carboxyl, (C 1 -C 6)alkoxycarbonyl, formyl, acyl, thioester, thioacetate, thioformate, (C 1 -C 6)alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino, amido, amidine, imine, cyano, nitro, azido, sulfhydryl, (C 1 -C 6)alkylthio, sulfate, sulfonate, sulfamoyl, sulfonamido, sulfonyl, 3-10 membered heterocyclyl, (C 5 -C 7)aryl(C 1 -C 6)alkyl, (C 5 -C 7)aryl, and 5-7 membered heteroaryl.