New antiparasitic agent derivatives of milbemycin and avermectin

摘要

Antiparasitic compounds of formula (I) wherein the broken line at the 22-23 position represents an optional bond and either this bond is present and R1 is absent or this bond is absent and R1 is H, OH, oxo or oximino optionally substituted by C1-C8 alkyl group, R2 is C1-C8 alkyl, C2-C8 alkenyl or C3-C8 cycloalkyl group, or a 3- to 6- membered heterocyclic ring containing a sulphur or oxygen atom, said ring being saturated or fully or partially unsaturated and optionally substituted by one or more C1-C4 alkyl groups or halogen atoms, R3 is H or OH, and R4 is H or a group capable of being hydrolyzed in vivo to yield a compound in which R4 is H, R5 is OH, optionally substituted with a group capable of being hydrolyzed in vivo to yield a compound in which R5 is OH, and R6 is H or C1-C4 alkyl or R6 is H and R5 is amino, optionally substituted with at least one group selected from C1-C8 alkyl and acyl groups.