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

摘要

The reaction of β-dicarbonyl phenyliodoniumnylides with diphenylketene at room temperature affords mixturesnof lactone and aurone derivatives. The initial electrophilic attack ofnthe iodonium ylide on the Cβ position of the diphenylketene,nfollowed by cyclization of the zwitterionic species, and subsequentnejection of iodobenzene, affords the lactone and aurone cycloadducts. Treatment of β-dicarbonyl iodonium ylides with acylnchlorides yields α-chloroenones with good to excellent yields.