Synthetic studies for novel structure of α-nitrogenously functionalized α-fluorocarboxylic acids. Part III. Some reactions of α-bromo-α-fluorocarboxylic acids and their ethyl esters with sodium azide

Abstract Synthesis of a novel group of α-azido-α-fluorocarboxylic acid derivatives has been attempted by azidation of the corresponding α-bromo-α-fluorocarboxylic acids or ethyl esters. Although ethyl azidofluoroacetate was obtained, over-azidation occurred very readily in most cases to afford geminally diazidated compounds. Attempted conversion of ethyl azidofluoroacetate into azidofluoroacetic acid by alkaline hydrolysis or by treatment with trimethylsilyl bromide resulted mainly in the formation of defluorinated products. It was found that, although α-fluorocarboxylates are generally considered stable, defluorination occurs under nucleophilic conditions if an additional labilizing group is present on the same carbon atom as the fluorine.