A study of fluorodecarboxylation using xenon difluoride

• Main Author: Shaw, Maxine M.
• Published: Keele University 2005
• Subjects: 546.755
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.483584

The modes of reaction of xenon difluoride are still not completely understood. The reagents' varying stability under different reaction conditions has given it the reputation of being somewhat unpredictable. An in depth NMR stability study of xenon difluoride in various solvent I container systems has been undertaken, which has improved our understanding of how the reagent may behave with substrates under a variety of different conditions. The reactions of trimethylsilyl esters with xenon difluoride have been investigated. Reactions of xenon difluoride are catalysed by Pyrex and therefore this reaction was studied in both Pyrex and PTFE vessels. Fluorodecarboxylation is the major reaction in PTFE, but this is not the case for the reactions in Pyrex. A further investigation of the reactions of carboxylic acids with xenon difluoride has also been performed. Again, this reaction was studied in both Pyrex and PIFE containers. Fluorodecarboxylation is the major reaction in PIFE, but in Pyrex no fluorination is observed; in these vessels a rearrangement mechanism predominates. The identification of minor as well as major products from these reactions has allowed the determination of possible mechanistic pathways for these processes. Xenon difluoride is believed to react largely via an SET mechanism in PTFE vessels and via a xenon fluoro-ester intermediate, of the type RC02XeF, in Pyrex. An additional study of the incorporation of various nucleophiles (X) into these reactions has aided in mechanistic studies and also provided a potential route to compounds of the form RX (where acid = RCO2H).