The Question of Electrophilic vs Nucleophilic Addition of Cyclic β‑Dicarbonyl Phenyliodonium Ylides: Electrophilic Cycloaddition of Diphenylketene

The reaction of β-dicarbonyl phenyliodonium ylides
with diphenylketene
at room temperature affords mixtures of lactone and aurone derivatives.
The initial electrophilic attack of the iodonium ylide on the Cβ position of the diphenylketene, followed by cyclization
of the zwitterionic species, and subsequent ejection of iodobenzene,
affords the lactone and aurone cycloadducts. Treatment of β-dicarbonyl
iodonium ylides with acyl chlorides yields α-chloroenones with
good to excellent yields.