Herbicidal compositions containing compounds of the formula ##STR1## where R.sup.2 is hydrogen, hydrocarbyl or substituted hydrocarbyl radical; R.sup.2a is hydrogen or methyl and R.sup.2 and R.sup.2a may together form a ring; R.sup.5 is hydrogen, alkyl, haloalkyl or cyanoalkyl; R.sup.r is aryl, substituted aryl or heterocyclyl.