abstract |
A compound of formula (I) or a biologically acceptable salt or solvate thereof: wherein X represents O or S; R 1 represents C 1-6 alkyl, C 3-8 cycloalkyl, C 3-8 cycloalkylmethyl or C 3-8 cycloalkenyl. Any of these may optionally be substituted by one or more methyl groups or halogen elements. Or R 1 represents aryl, substituted aryl, heteroaryl or substituted heteroaryl; R 2 represents hydrogen, methyl or methylene located in the α or β configuration; R 3 and R 4 are the same or different and each independently represent a hydrogen, halogen or methyl group; And Represents a single or double bond. |