The preparation and investigation of some hetero-atom onium ions and their use in organic synthesis

A short review of cases where acyl- or alkoxycarbonyl onium salts have been prepared or postulated as intermediates is presented. The reaction of trialkylamines with chloroformate esters and acyl halides has been re-examined. Chloride ion proved to be too nucleophilic an anion to be able to isolate the salts. The route of decomposition is discussed in detail. The reaction of amines with chloroformates in the presence of antimony pentachloride has been investigated. Chloride ion exchange using triethyloxonium tetrafluoroborate has been achieved in the reaction of phenyl chloroformate with triethylamine, and the 13C nmr spectrum of this salt is discussed in detail. [Continues.]