There are described new compounds of formula ##STR1## in which E is selected from the group consisting of residues of formula ##STR2## in which R" is selected from the group consisting of amino, vinyl, allyl, ethynyl, C.sub.1 -C.sub.5 alkyl, C.sub.1 -C.sub.5 alkoxy, or C.sub.1 -C.sub.5 alkylthio or a C.sub.1 -C.sub.5 alkyl group susbstituted by at least one halogen atom; and hydrogen; in which R.sup.1 and R.sup.2 are each selected from the group consisting of hydrogen, halogen, methyl and ethyl; and R' is selected from substituted phenyl when R" is other than hydrogen, and phenyl, thienyl and substituted phenyl and thienyl when R" is hydrogen. The compounds are useful in the control of parasites. Certain of the compounds have antimicrobial properties.