Thermal Decomposition of 2,2,6-Trimethyl-4H-1,3-dioxin-4-one and 1-Ethoxybutyn-3-one. Acetylketene

Article abstract of DOI:10.1021/jo00200a018

Acetylketene was first mentioned in the literature in 1907, but only in recent years has evidence for the existence of this species appeared.Previous work has indicated that acetylketene may be generated by pyrolysis of the title dioxinone, and we now present further chemical evidence in support of its presence.In particular, ethoxyacetylenes are known to generate ketenes upon pyrolysis.When the title alkyne was heated, it provided an intermediate that in six different trapping experiments gave the same products as those obtained via pyrolysis of the dioxinone.Acetylketene chemistry is predominated by <4 + 2>-cycloaddition reactions; no evidence for conversion to β-crotonolactone or diketene was seen.