L-Proline: An Efficient Organocatalyst for the Synthesis of 5-Substituted 1H-Tetrazoles via [3+2] Cycloaddition of Nitriles and Sodium Azide

A simple and efficient route for the synthesis of a series of 5-substituted 1H-tetrazoles using L-proline as a catalyst from structurally diverse organic nitriles and sodium azide is reported. The prominent features of this environmentally benign, cost effective, and high-yielding L-proline-catalyzed protocol includes simple experimental procedure, short reaction time, simple workup, and excellent yields making it a safer and economical alternative to hazardous Lewis acid catalyzed methods. The protocol was successfully applied to a broad range of substrates, including aliphatic and aryl nitriles, organic thiocyanates, and cyanamides.