Protic solvents and higher temperatures gave a mixture of the double Diels-Alder adduct and unreacted benzoquinone. The product of this reaction was tautomerized to the hydroquinone by stirring with 5% sodium hydroxide in a 50% ethanol/water mixture and acidified with aqueous HCl solution. The starting material precipitates as a solid upon acidification and was converted to the nonaflate as described by Swager, save that triethylamine rather than trimethylamine was used as the base to scavenge HF produced by the reaction.