... Reagent grade acetonitrile was distilled from anhydrous magnesium sulfate. Dioxane was purified by the method Of Fieser; see LF Fieser, "Experiments in Organic Chemistry," 3rd ed, DC Heath, Boston, Mass., 1955, pp 284-285. Page 3. 3924 J . Org. Chem., 1'01. 38, No. ...