Safe and fast tetrazole formation in ionic liquids

The [2+3] cycloaddition of nitriles and azides is reliable for intramolecular reactions, but the hazards with volatile azides in intermolecular reactions are tremendous. Zinc catalysis in aqueous solution is a magnificent improvement, but requires the removal of the zinc salts from the acidic product. Herein, we report safe solvents featuring low vapor pressure and good solubility of NaN3. Ionic liquids based on alkylated imidazoles combined with microwave heating turned out to be a solution for the given tasks.