Abstract: Compounds of the formula: wherein X represents a single or a double bond; R1 is H or OH; provided that when X is a single bond, R1 is H or OH, and when X is a double bond, R1 is absent; R2 is H, C1-C8 alkyl, C2-C8 alkenyl, C2-C8 alkynyl, alkoxy-alkyl or alkylthioalkyl containing from 1 to 6 carbon atoms in each alkyl or alkoxy group, wherein any of said alkyl, alkoxy alkenyl or alkynyl groups may be substituted by one or more halo atoms; or a C3-C8 cycloalkyl or C5-C8 cycloalkenyl group, either of which may be substituted by methylene or one or more C1-C4 alkyl groups or halo atoms; or a 3 to 6 membered oxygen or sulphur containing heterocyclic ring which may be saturated, or fully or partially unsaturated and which may be substituted by one or more C1-C4 alkyl groups or halo atoms; or a group of the formula SR5 wherein R5 is C1-C8 alkyl, C2-C8 alkenyl, C2-C8 alkynyl, C3-C8 cycloalkyl, C5-C8 cycloalkenyl, phenyl or substituted phenyl wherein the substituent is C1-C4 alkyl, C1-C4 alkoxy or

Abstract: Compounds of the formula: ##STR1## wherein X represents a single or a double bond; R.sup.1 is H or OH; provided that when X is a single bond, R.sup.1 is H or OH, and when X is a double bond, R.sup.1 is absent;R.sup.2 is H, C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.8 alkynyl, alkoxy-alkyl or alkylthioalkyl containing from 1 to 6 carbon atoms in each alkyl or alkoxy group, wherein any of said alkyl, alkoxy alkenyl or alkynyl groups may be substituted by one or more halo atoms; or a C.sub.3 -C.sub.8 cycloalkyl or C.sub.5 -C.sub.8 cycloalkenyl group, either of which may be substituted by methylene or one or more C.sub.1 -C.sub.4 alkyl groups or halo atoms; or a 3 to 6 membered oxygen or sulphur containing heterocyclic ring which may be saturated, or fully or partially unsaturated and which may be substituted by one or more C.sub.1 -C.sub.4 alkyl groups or halo atoms; or a group of the formula SR.sup.5 wherein R.sup.5 is C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.