von Braun‐Rudolf Synthesis

Abstract The preparation of substituted tetrazoles by the treatment of imidyl chlorides with anhydrous hydrazoic acid in benzene or chloroform, is generally known as the von Braun‐Rudolf reaction, von Braun‐Rudolf synthesis, or von Braun–Rudolf tetrazole synthesis. All the mechanistic features of the reaction have been discussed. It has been reported that the von Braun‐Rudolf synthesis also promotes some side reactions that lead to ureas (via carbodiimides) and anilinotetrazoles under a strongly proton‐donating environment. In addition, an intramolecular cyclization of azide and nitrile has been developed to form a tetrazole [5,1‐c]‐[1,4] benzothiazine. This reaction has been applied for the preparation of tetrazole derivatives.