1,3-Dioxane-4,6-dione, 5-(methoxymethylene)-2,2-dimethyl- 15568-85-1 5-(Methoxymethylene)-2,2-dimethyl-1,3-dioxane-4,6-dione Methoxymethylene cyclic isopropylidene malonate Methoxymethylene meldrum's acid