Ylidions: A New Reactive Intermediate Prepared by Photosensitized One-Electron Oxidation of Phenacyl Sulfonium Ylides

Article abstract of DOI:10.1021/ja00200a038

The chemistry of a series of phenacyl sulfonium ylides was studied.Their photosensitized one-electron oxidation by 9,10-dicyanoanthracene generates ylidions, a new class of radical cation intermediates.In some cases, the ylidions cleave to form a free alkyl radical and a cation; in others, they are attacked by nucleophiles or by an alkene.The chemical properties displayed by the phenacyl sulfonium ylidions appear to be controlled primarily by the nature of the sulfur-bound alkyl groups.The direct photolysis and thermolysis of the phenacyl sulfonium ylides was examined for comparison with their one-electron oxidation.Some of the ylides undergo the Stevens rearrangement either when heated or photolyzed.Contrary to an earlier report, there is no evidence that direct photolysis of a phenacyl sulfonium ylide leads to formation of benzoylcarbene.