Compounds of the formula: ##STR1## wherein X is O or S; R and R.sup.1 are substituted or unsubstituted alkyl, alkenyl, alkynyl or cycloalkyl or R and R.sup.1 may be joined to form a heterocyclic ring; R.sup.2 is substituted or unsubstituted cycloalkyl; and n is 0, 1 or 2 are disclosed as well as their postemergence and preemergence selective herbicide use against both monocot and dicot weeds in crops such as sugarbeets, cotton, soybeans and rice.