Preparation of Some Unsymmetrical Methylenedionium Salts and Their Reaction with Nucleophiles

The synthesis of (ethylmethylsulfoniomethyl)pyridinium—, trimethyl(ethylmethylsulfoniomethyl)-ammonium—, 1-ethyl-3,3-dimethyl- 1 thionia-3-azoniacyclopentane—, 1,3,3- trimethyl-l-thionia-3-azoni-acyclopentane—, (triphenylphosphoniomethyl) pyridinium—, ethylmethyl (triphenylarsoniomethyl)sulfo-nium — and (ethylmethylsulfoniomethyl)triphenylphosphonium bistetrafluoroborate is described. The NMR spectra of these unsymmetrical methylenedionium salts, with particular reference to the methylene protons resonance between two onium groups, are discussed. The reaction of these onium salts with numerous nucleophiles such as pyridine, piperidine, triethylamine, triphenylphosphine and triphenylarsine, is also discussed. KEY WORDS : Synthesis of unsymmetrical methylenedionium salts / NMR spectra of unsymmetrical methylenedionium salts / Re-action of unsymmetrical methylenedionium salts/ Symmetrical methylenebisonium salts, such as methylenebisammonium, methyl-enebissulfonium and methylenebisphosphonium salts are rather easily obtainable and have been targets of research both in the fields of physical organic and synthetic chemistry. However, the unsymmetrical ones have received relatively little study