A simple, efficient, and general method has been developed for the synthesis of 1- substituted-1H-1, 2, 3, 4-tetrazoles via a three-component condensation of amine, trimethyl orthoformate, and sodium azide in presence of a catalytic amount of indium triflate under solvent-free conditions. The reaction proceeds smoothly to generate the corresponding 1- substituted tetrazoles in moderate to excellent yields under heating.
[El-Ahl, Abdel-Aziz S.; Amer, Fatty A.; Elbeheery, Akram H. Phosphorus, Sulfur and Silicon and the Related Elements, 2011 , vol. 186, # 11 p. 2226 - 2235]