Azidation, Diazo Transfer [Synthetic Reagents]

　Organic azide compounds can be synthesized in a simple manner by the reaction of sodium azide with halogenated alkyl compounds, or the reaction with trifluoromethanesulfonyl azide and primary amines, however, these azide sources potentially have highly explosive character, which makes it difficult to handle. 2-Azido-1,3-dimethylimidazolinium hexafluorophosphate [A2457], which was developed by Kitamura et al., is a crystalline diazotransfer reagent having high thermal stability and low explosibility. The differential scanning calorimetry (DSC) experiment of A2457 has revealed that the exothermic decomposition temperature was approximately 200 °C. Moreover, A2457 has tested negative for the impact and friction-sensitivity tests.¹⁾ Under basic conditions, 9 reacts with several kinds of primary amines in a short time to afford the corresponding diazo compounds in high yields. In these reactions, the by-products can be removed by conventional extraction procedures due to their high solubility in water.