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.
Production of c-5-aralkoxy-r-2-substituted-5-alkyl-1,3-dioxanes by epoxidizing the double bond of a 2-substituted-5-alkylidene-1,3-dioxane to form a cis epoxide, hydrogenolyzing said epoxide to form a 2-substituted-5-alkyl-5-hydroxy-1,3-dioxane in which there is a cis relationship between the 5-hydroxy and the 2-substituent, and etherifying said hydroxydioxane with an aralkyl halide.