Isopropenyl Acetoacetate and the Reaction of Diketene with Acetone

Article abstract of DOI:10.1021/jo00200a017

The acid-catalyzed reaction of diketene with acetone to form 2,2,6-trimethyl-4H-1,3-dioxin-4-one, when conducted by using acetone-d6, yields a product with a high degree of deuterium scrambling.This scrambling is inconsistent with the intermediacy of either acetylketene or a 1,4-dipolar form of diketene in the reaction.Pathways involving isopropenyl acetoacetate or its protonated form are judged more compatible with the labeling results.Authentic isopropenyl acetoacetate was synthesized by using a retro-Diels-Alder route and was found to be converted to the title dioxinone under the diketene-acetone reaction conditions.