Some representatives of the compounds having the general formula (I), such as those wherein Aryl is as defined above, R1 is hydrogen or an optionally substituted alkyl or cycloalkyl group and R2 is an optionally substituted alkyl or alkoxy group, exert pesticidal, primarily herbicidal effects (see e.g. R. Wegler: Chemie der Pflanzenschutz- und Schadlingsbekampfungsmittel, Springer Verlag, Berlin-H