β-Aminovinylphosphonium Salts—A Novel Synthesis, Properties, and Structure
摘要:
The deacylation of easily accessible -(N-acylamino)vinylphosphonium salts with methanol or some other nucleophiles gives -aminovinylphosphonium salts in good yields. As indicated by the spectroscopic properties and by the results of single crystal X-ray diffraction studies the N-alkyl derivatives of the investigated compounds should be considered as strongly resonance stabilized -iminium ylides rather than -aminovinylphosphonium salts. In the case of N-aryl derivatives, the -iminium ylide resonance structures are probably less pronounced.
A reaction of beta-carbonyl phosphorus ylides with imidoyl halides gives hitherto unknown beta-(N-acylamino)vinylphosphonium salts. The same product can be obtained using the N-monosubtituted amide/Ph3PBr2/Et3N system instead of imidoyl halide. The key step of the reaction probably involves an intramolecular [1,3] O-to-N migration of the vinyl group, converting the primary O-imidoylation product into beta-(N-acylamino)vinylphosphonium salt.