On the Inherent Instability of α-Amino α‘-Fluoro Ketones. Evidence for Their Transformation to Reactive Oxyvinyliminium Ion Intermediates

α-Amino α‘-fluoro ketones are shown to be inherently unstable intermediates. Evidence is presented that they undergo enolization toward the
amino group followed by expulsion of fluoride ion, forming a proposed oxyvinyliminium ion (amino-substituted oxyallyl cation). In protic,
nucleophilic media the proposed intermediate is trapped by solvent. In the presence of a reactive diene, [4 + 3] cycloadducts have been
isolated. Prior observations concerning fluorinated amino ketones are discussed in light of these findings.