2-Azido-1,3-dimethylimidazoliniumSalts: Efficient Diazo-Transfer Reagents for 1,3-Dicarbonyl Compounds

We have developed the diazo-transfer of 2-azido-1,3-dimethylimidazolinium salts to 1,3-dicarbonyl compounds. 2-Azido-1,3-dimethylimidazolinium chloride (ADMC) was prepared by N-nitrosation of N-aminoguanidine or by the reaction of 2-chloro-1,3-dimethylimidazolinium chloride (DMC) and sodium azide. The corresponding phosphate, ADMP, was isolated as a crystal, and was found to be a stable and safe reagent. Both ADMC and ADMP reacted with 1,3-dicarbonyl compounds under mild conditions to give 2-diazo-1,3-dicarbonyl compounds in high yields, which are easily isolated because the by-products are highly soluble in water.